Exam 2 Flashcards
How is MTB transmitted?
Person-to-person via aerosol droplet nuclei
Who is the reservoir for MTB?
Humans only
Prosector’s Warts are indicative of inoculation with what disease?
MTB
MTB largely affects what age ranges?
Infants and older adults (bimodal age distribution)
MTB manifestations in infants/IMC? (2)
- Hematogenous dissemination
2. Meningitis
MTB manifestations in older pts? (2)
- Failure of immune sx
2. +/- reactivation of latent infection
Infection risk factor for children?
Close contact w/ infected caregiver
What are the causative agents of TB? (3)
- Mycobacterium tuberculosis»_space;
- Mycobacterium bovis (Consumption of unpasteurized milk/ contact w/ infected animals)
- Mycobacterium africanum (West African Counties, no animal reservoirs, spread by food)
Strain of Mycobacterium used to make TB, BCG vaccine?
Mycobacterium bovis, given in highly endemic areas
MTB characteristics (shape, cell wall, oxygen status, motility, heat sensitivity, growth) ?
- Bacillus
- Mycolic acid
- Obligate aerobe
- Non-motile
- Heat sensitive, killed by pasteurization
- Alveolar macrophage
MTB staining
- Acid Fast
- Ziehl-Neelsen or Kinyoun stains
- Cells resistant to staining and decolorization once stained
MTB virulence factors
No classic virulence factors or toxin, structure feature create issues for the pt
- Mycolic acid
- Cord factor - myoside,
- Lipoarabinomanna (LAM) - inhibits cell mediated immunity, scavenges ROI
CXR findings for TB?
Fibrotic and calcified tubercle
Risk of infection spread w/ latent TB?
No risk
Are pts w/ latent TB treated?
Yes
Are pts w/ reactivation or secondary TB infectious?
Yes
Cause of Miliary Tb? (2)
- Lypmhohematogenous spread of primary infection
2. Via latent focus w/ subsequent spread
Tests for DX of Tb? (5)
- XR consistent w/ TB
- Skin test reactivity
- Sputum stain/broth cx to detect acid fast bacteria
- Rapid blood test (release of IFN-Y)
- GeneXpert Rapid test for MTB and Rifampin resistance
Goal of tx for MTB?
- Recognize, isolate, and treat infected persons (Latent and active)
MAC characteristics (shape, cell wall, oxygen status, motility, growth)?
- Bacilli
- Acid fast, Weakly G+
- Aerobic
- Ubiquitous (water, soil, plants)
- Slow growing
MAC w/ person-to-person transmission?
NO
Pt isolation required w/ MAC infection?
No
MAC relationship w/ HIV pts?
Opportunistic pathogen. Leading cause of NTM infections in HIV+ pt
Lady Windermere’s syndrome is associated w/ what TB pathogen?
MAC
What gender/age range is Lady Windermere’s syndrome seen in?
Elderly, non-smoking female
Type of MAC disease in IMC (AIDs) pts?
Disseminated disease (no organ spared)
Findings/tests for NTM for dx? (3)
- Microscopy reveals acid fast bacteria and culture
- Must ecxlude other etiologies (Fungi, TB), sterile site isolation
- CXR w/ + pulmonary lesions
- Final ID via molecular techniques (PCR to determine 16S rRNA sequence)
MAC tx HIV- pts?
ABX until sputum cultures are negative for 1 yr
MAC tx in HIV + pt w/o infection?
Chemoprophylaxis w/ CD4 < 50 cell/uL, discontinue 3 months after CD4 > 100 cell/uL
MAC tx in HIV+ pt w/ MAC infection
- Lifelong (if w/o immune reconstitution)
- Begin tx for 2 weeks then anti-HIV HAART
Mycobacterium abscessus is especially difficult to treat in what disease population?
CF
MTB pathogenesis?
Granulomas (2-6 weeks post infection) → caseous lesions (fibrotic tubercle) → calcifies & seen on x-ray → disease stops
MTB infection outcomes? (5)
- Immediate resolution (no active TB) - innate immune system (alveolar macrophage) able to clear bacteria
- Primary disease
- Progressive primary (active) disease
- Latent infection (inactive bacteria, - signs/sx, not infectious, treatment necessary)
- Endogenous reactivation/secondary TB (+ signs/sx, infectious, insidious, lesions: caseous lesions → TB bacilli to bronchi → hematogenous spread
What is HAART?
Highly acute anti-retroviral therapy
Coryza, cough and conjunctivitis is concerning for what disease?
Measles
Koplick’s spots are diagnostic for what disease?
Measles
Mealse rash starts and spreads where?
Head, spread to body
When is a measles pt the sickest?
During rash/ highest fever (3-4 days after prodrome)
Acute symptomatic encephalitis is a complication associated with what disease?
Measles
also some associated w SSPE = subacute sclerosing panencephalitis
What complication is responsible for most deaths in measles pts?
Pneumonia
Is there a healthy carrier state associated with measles?
No, none known
Transmission of measles is via?
Respiratory droplets (highly contagious)
Is measles a disease of adulthood or childhood?
Primarily a disease of childhood (might be changing)
FA test for pt w/ measles will show?
Multinucleated giant cells
Largest preventative measure for measles?
MMR vaccine
also immune globulin BayGam for exposed non-immune subjects
MMR II is what type of vaccine?
Live, attenuated vaccine
Who should never receive MMR vaccine?
Pregnant, IMC
What % of population must be vaccinated to halt measles persistence?
95%
Rubella is also referred to as? (2)
- German Measles
2. “little red”
What age group often escaped rubella infection?
Children
Congenital rubella syndrome (CRS) is a complication due to what?
Maternal rubella infection during first trimester (worst prognosis earlier then infection, 1st month > 4th month)
Cataracts, hearing loss, and cardiac defects are sx of what?
Congenital rubella syndrome (CRS)
2 unique properties of HSV?
- Capacity to invade and replicate in CNS
2. Ability to establish latent infection
Shallow vesicles on erythematous +/- crusting and ballooning is concerning for?
HSV
Can the primary HSV infection be asymptomatic?
Yes
How does HSV become a latent virus?
Retrograde transport of virus through sensory neurons –> infection of dorsal root ganglia
What is the timeframe for completely clearing an HSV infection from the body?
None. HSV is for life!
Stress, menses, sunlights and nutrition are all triggers for what viral infection?
HSV
If a pt has a larger and more extensive initial outbreak with HSV, will their probability of recrudescence be higher or lower?
Higher
Will recrudescence of HSV occur in the presents of active humoral and cellular immunity?
Yes
Who is the reservoir for HSV?
Humans only
Can you transmitted HSV infection even if asymptomatic?
Yes
Are HSV-1 infection common in early life or later life?
Early life via casual contact
How are HSV-2 infections transmitted?
Sexual contact
Presence of enlarged or fused cells on Tzanck smear is concerning for what disease?
HSV
ACV (Acyclovir) is effective in treating HSV because viral enzyme thymidine kinase phosphorylates the drug for activation and then what?
Halts viral DNA replications b/c it lacks 3’-OH group
Will only get into infected cells when active
Varicella-zoster virus is responsible for what 2 disease states?
- Chickenpox
2. Shingles
Asymmetrical vesicular pruritic rash is concerning for what disease?
Chickenpox
Viral infection through conjunctiva or respiratory tract mucosa is concerning for what disease?
Chickenpox
Who is the only reservoir for chickenpox?
Humans
VZV infections peak during what seasons?
Winter-SPring
What age group has the highest incidence of VZV?
5-9 y/o
When is VZV pt most contagious?
1-2 before appearance of lesions and 4-5 days after
Are prodromal VZV present in older children and adults or younger children?
Younger children
VZV rash is primarily located where?
On the trunk
Is aspirin recommended in tx of chickenpox?
No, concerning for Reyes syndrome
TX for Chicken pox?
Sx relief - self limited
Acyclovir
Immune serum VariZig (high risk)
Varivax is the vaccine for what disease?
VZV
IS the VZV vaccine safe in pregnancy?
No
Will shingles cross midline?
No, unilateral dermatomal distribution
Shingles is recrudescence of what viral infection?
VZV
Searing, burning, stabbing lesions that don’t cross midline are concerning for?
Shingles
Most common complication fo shingles?
Postherpetic neuralgia
Can a pt present with shingles but never have had or been vaccinated against chicken pox?
No
Zostavax and Shingrix are vaccines against what?
Shingles
Is Zostavax or Shingrix a live vaccine?
Zostavax
Is Zostavax or Shingrix given in 2 doses?
Shingrix
Exanthem subitum, roseola infantum/6th disease are caused by what?
Human Herpes Virus-6 (HHV-6)
HHV-6 is dx by what? (2)
- Detection of AB by EIA
2. PCR
High fever w.o any obvious sources is concerning for what?
HHV-6
TX of HHV-6 does not require? (3)
- Isolation
- Anti-viral therapy
- Primary preventative measures
Fifth’s disease/ Erythema infectiosum is causes by?
Parvovirus B19
Prodrome of this disease is follow by maculopapular rash in “slapped cheeked” appearance?
Parvovirus B19
Arthralgia or arthritis follow maculopapular rash may be concerning for?
Parvovirus B19
Parvovirus B19 is most common in what seasons?
Later winter and spring
Virus that produces warts?
HPV
HPV 6 & II produce anogenital warts or cervical dysplasia and cancer?
Anogenital warts
HPV 16 & 18 produce anogenital warts or cervical dysplasia and cancer?
Cervical dysplasia and cancer?
Age range for Gardasil 9?
M/F 9-45
Dermatophytes require what for growth?
ketatin (hair, skin, nails)
Do dermatophytes infect mucosal surfaces?
No
What enzymes allows dermatophytes to inhabit keratinized regions of the body>
Keratinase
Dermatophyte test medium (DTM) allows for early detection of infection or can only be used to different source of dermatophyte?
Early detection
Arthroconidium is what?
The infective stage of disease for dermatophytes
Trichophytin is what? (2)
- Galactomannan peptide
2. Crude antigen of dermatophytes (CHO component = immediate response, Peptide component = delayed response)
How does 10% potassium hydroxide allow for visualization of fungi?
Digests human tissues, leaving fungal components intact
Dermatophytes utilize nitrogen compounds preferentially over carbs. DTM will turn what color?
Red (alkaline)
Dermatophyte test medium (DTM) is selective and differential for what?
Selective: Cyclohexamide and ABX
Differential: fermentation of sugars
Animal pathogens that may be transmitted to people are what?
Zoophilic
Antropholilic Dermatophytes are spread via what transmission?
Human to human
Soil to people transmission is what?
Geophilic
Geophilic dermatophytes will invade non-viable or viable keratinized tissue?
Non-viable
Fungi prefer dry or moist areas of the body?
Moist
Globally where are fungal infections more prevalent?
Tropics
Microconidia, macroconidia and sexual spores are infectious or non-infectious?
Infectious
Fragmented hypheal elements in hair, nails, outer skin are what?
Arthrospores
Lesions with inflamed edges and a central clearings are concerning for what infectious pathogen?
Fungi
Transmission pattern for arthrospores?
Person to persons
Are arthrospores infectious?
Yes
Microconidia is uni or multi cellular?
Uni
Macroconidia is uni or multicellular?
Multi
Classification for an allergic dermal reaction to fungal antigen occurring in areas devoid of organisms
Dermatophytid
Most common dermatophytid?
Athlete’s foot
How are dermatophytid reactions spread?
Itching
Will dermatophytid be present at only 1˚ or 1˚ and 2˚ sites?
Only primary
“Id reaction” is associated with what fungal infection?
Dermatophytid
What is an “id reaction” treated as?
An allergy
What is the most common trichophyton species?
T. mentagrophytes
Are trichophyton often fluorescent or not fluorescent?
Not fluorescent
What do all trichophyton species make?
Pencil-shaped macroconidia w/ thin walls
What 3 things do trichophyton produce?
Hyphae (spindle shaped), microconidia, macroconidia
What is the most common causative agent of tinea captitis?
M. canis
What disease is described as mostly a childhood disease that involves the hair and scalp?
Tinea capitis
What are the 2 types of ringworm infections?
Endothrix (infects throughout follicle)
Ectothrix
What infection is associated with certain species producing a black dot ringworm, intense inflammation, scarring/ permanent alopecia, and can be zoonotic?
Tinea capitis
With tinea capitis, infected hair can break off and lead to what?
Alopecia
If a patient presents with itching, peeling, and crackling of the skin in the toe webs/ soles of feet, what should you be concerned about?
Tinea pedis (most prevalent of dermatophytoses)
What are predisposing factors for tinea corporis and tinea cruris?
Diabetes, obesity, excessive perspiration
How are tinea corporis and tinea cruris transmitted?
Direct and indirect contact objects (towels, clothing, bed linens)
What is tinea unguium?
Onychomycosis (ringworm of the nail)
What infection is associated w/ the following:
- Finger/ toenails become discolored/ thick
- May be mistaken for psoriasis
- Usually has fungal involvement (Candida)
Tinea unguium
What are the most commonly encountered opportunistic mycoses?
Candidiases
What infection is associated with colonization of normal flora of the skin and mucous membranes?
Candidiases
What infection is associated with the following:
- Absence of competing normal flora
- Introduction to abnormal site
- “Pathologic” change in microenvironment
- Inborn or acquired immune defect
- Use of broad-spectrum abx
Candidiases
Although candida albicans does not have many virulence factors, all species are capable of attachment, and what is the most adhesive?
Germ tube more adhesive than yeast cell
How is a Candida infection diagnosed?
Direct microscopic exam
- Large G- cells
- Yeast cells
- Pseudohyphae
- True hyphae
Besides direct microscopic exam, how is a Candida infection diagnosed?
Cultures (germ tubes)
Histology
Serology
What is tinea versicolor aka?
Malassezia furfur
What fungi is described as microscopically having short, unbranched hyphae and somewhat spherical cells and also has yeast like colonies?
Malassezia furfur
If you see a “spaghetti and meatballs” arrangement on a microscopic exam, what fungal infection should you be suspicious of?
Malassezia furfur
What type of GF is required for growth of Malassezia furfur?
Lipophilic (fat, sebaceous glands)
In what populations is Malassezia furfur most commonly found?
Tropics, young adults
What fungal infection is associated with macular patches of depigmented or hyper pigmented skin that may enlarge and can lead to dandruff?
Malassezia furfur
How can Malassezia furfur be identified?
Microscopic exam in skin scrapings, KOH prep
What fungal infection is tinea nigra aka?
Hortaea werneckii
What fungal species is dimorphic and can grow in saturated salt solutions?
Hortaea werneckii
What fungal species is identified as a tropical disease, results in brownish lesions (melanin), and is identified with KOH and microscopy?
Hortaea werneckii
When is a bacterial skin infection considered complicated?
Pre-existing wound care Deeper tissues Requires surgery Unresponsive to therapy/ recurrent Associated w/ underlying disease
Recurrent infections raise concern over colonization with what?
Resistant bacteria or underlying issues
Although normally inoculum of bacteria (staph) introduced through breaks in skin is not large, what happens if a foreign body (splinter, stitches) is present?
Infectious dose drops dramatically
What disease is associated with the sebaceous follicles and is a noninfectious form of folliculitis?
Acne vulgaris
What is often the initial trigger for acne vulgaris?
Androgen hormones
What bacteria responsible for acne vulgaris is G+, anaerobic rod, and on normal skin flora (sebaceous glands)
Propionibacterium acnes
What does inflammatory acne develop?
When follicular contents rupture into dermis
papule > pustule > nodule
What is the usual cause of Folliculitis?
Staph. aureus
If a pt presents w/ mild pain, itching/ irritation with pustules or nodules surround hair follicles?
Folliculitis
If folliculitis is not responding to tx, what should be performed to r/o other possible causes?
Gram stain
r/o G- etiology or MRSA
What are the 2 primary pathogens responsible for superficial folliculitis?
Staph. aureus and Pseudomonas aeruginosa
Which pathogen is responsible for the majority of abscess-type infections, is G+, and coagulase-+ cocci in clusters?
(superficial folliculitis)
Staph. aureus
Which pathogen is described by the following: - G- rod - Opportunistic pathogen - Ubiquitous - Pyocyanin/ pyoverdin (superficial folliculitis)
Pseudomonas aeruginosa
P. aeruginosa is often the cause of what type of folliculitis?
“Hot tub” folliculitis
If a pt presents 8-48 hrs post exposure to contaminated water and is complaining of an itchy maculopapular rash with some pustules, what is the likely responsible pathogen?
Pseudomonas aeruginosa
A furuncle (boil) is an abscess caused involving a hair follicle and surrounding tissue caused by what pathogen?
S. aureus
What are clusters of furuncles with subcutaneous connections that extend into the dermis and subcutaneous tissue?
Carbuncles
What other sxs might accompany carbuncles?
Fever and prostrations
What populations are more commonly affected by furuncles and carbuncles?
Obese, immunocompromised, diabetic, elderly
If furuncles or carbuncles are > 5mm, do not resolve w/ drainage, are spreading, or occur in IMC/ subjects at risk of endocarditis, how are they treated?
Abx (effective against MRSA)
More aggressive combo therapy with rifampin if + fever/ multiple
What condition is a superficial skin infection with crusting or bullae and what is the most common pathogen cause?
Impetigo
Cause= steph, strep (or both)
What is the deeper, ulcerative form of impetigo?
Ecthyma
Moist environment, poor hygiene or chronic nasopharyngeal carriage of agents are RF’s for what disease?
Impetigo/ ecthyma
If a pt presents with clusters of vesicles that rupture and crust over around the nose and mouth, what should you be concerned for?
Non-bullous impetigo
What is the #1 cause of non-bullous impetigo?
S. aureus (with MRSA in 20%)
Strep. pyogenes co-infects frequently
In bullous impetigo, exfoliative toxin that disrupts epidermal cell connections results in vesicles enlarging to form what?
Bacteria-colonized fluid-filled bullae
What is the most common pathogen involved with bullous impetigo and what role does the toxin play?
S. aureus (specific strains)
Toxin does not disseminate beyond local sites of infection
A severe form of impetigo featuring deep invasion of the dermis caused by the same agent producing non-bullous impetigo is known as what?
Ecthyma
Lesions with hard crust that is deeper and thicker than impetigo underlying ulcerated tissue is known as what?
Ecthyma
Staphylococcal scalded skin syndrome is aka?
Ritter’s disease
Acute and extensive epidermolysis due to action of staph toxin (exfoliation) that splits the skin just beneath the granule cell layer is what?
Staphylococcal scalded skin syndrome
Why are the bullae in Staphylococcal scalded skin syndrome sterile (no bacteria or leukocytes)?
Due to toxin
Positive Nikolsky’s sign, skin peels easily, and desquamated areas look scalded fits the description for what condition?
Staphylococcal scalded skin syndrome
Is the mortality rate for scaled skin syndrome high or low?
Low
Erythema and edema to R LE (unitlateral) the appears deep w/in the dermis and has less distinct borders is concerning for erysipelas or cellulitis?
Cellulitis
Superficial cellulitis (erythema with raised lesions) w/ focal dermal involvement and distinct borders is concerning for what?
Erysipelas (st. Anthony’s Fire)
Most common pathogen for erysipelas?
Group A, B-hemolytic Streptococci, Strep pyogenes
How do erysipelas spread once dermis is infected?
Superficial lymphatic vessels
Will you always be able to pinpoint the source of cellulitis infection?
No, wound may not be evident
HEET (heat, erythema, edema, tenderness) is the hallmark for what bacterial skin infection?
Cellulitis
When treating cellulitis should you assume the infection is caused by a single pathogen?
No, may be mixed etiology
Why should NSAIDs be avoided in the treatment of cellulitis?
Can mask pain of developing myonecrosis (something more serious than cellulitis)
What is a warning sign that cellulitis infection might be necrotizing fascitis?
Out of proportion pain
Cellulitis pathogen associated w/ cat bite?
Pasteurella multocida
Redness, swelling warmth, pain + what signs/sx would make you concerned for a MRSA infection? (4)
- Fluctuance (evidence of fluid)
- Yellow/white center
- Central point (head)
- Draining pus or ability to aspirate pus w/ syringe
What gene can you screen for that might tell if you are Methicillin resistant?
MecA
Infections of the epidermis? (3)
- Erysipelas
- Impetigo
- Follicutlits
Infections of the dermis? (3)
- Ecthyma
- Furunculosis
- Cabunculosis
Infection of the superficial fascia? (1)
Cellulitis
Infection of the subQ tissue and fascia? (1)
Necrotizing fasciitis
Infection of the muscles? (1)
Myonecrosis (clostridial and nonclostridial)
Why is it difficult to dx NF w/o surgical intervention?
Initially overlying tissues appear unaffected
Why is muscle tissue spared from NF infection?
Generous blood supply
Type 1 NF pathogens are most common. What disease state disease state puts you at increased risk?
DM
If you have a hx of surgery, previous abscess or GI perforation are you at risk for Type 1 or Type 2 NF infection?
Type 1
Flesh eating bacteria or streptococcal gangrene more common in abdominal/groin area or the extremities?
Extremities
Pain out of proportion and skin color changes w/ bullae within 3-5 day of onset is concerning for?
Necrotizing fasciitis
What differentiates NF from cellulitis?
Failure to respond to ABX (cellulitis will respond w/in 24-48hrs to abx)
What is the tx for NF?
Surgical debridement/apmutation w/ IV ABX
Presence of no true pus, but brownish exudate and pain out of proportion/ rapid progression is concerning for?
NF
Gas gangrene is most caused by what pathogen?
Clostridium perfringens type A (90%)
- spore forming, G+, anaerobic bacillus
Gas gangrene primarily affects what tissue?
Muscle
Gas gangrene is also known as?
Clostridial myonecrosis
Skin that is tense/edematous, intensely tender, and crepitant (due to H2 gas) with bronze appearance is concerning for?
Gas gangrene
Rapid onset of pain ≤24 hrs following anaerobic cell/spore infection is concerning for?
Gas gangrene
Gram stain of tissue biopsy for gas gangrene will show what?
Muscle necrosis , gram variable rods, and tissue destruction
Hyperbaric oxygen therapy, surgery, and IV abx are tx for what dermal infection?
Clostridial myonecrosis
Causative agents for toxic shock syndrome? (2)
Staph aureus and strep pyogenes
Fever and sunburn like rash to entire body is concerning for what?
TSS
Early presentation for Strep TSS?
Soft tissue inflammation at site of skin infection
True or False: Pt’s w/ strep TSS are usually bacteremic and have NF?
True
Enterotoxin type B superantigen is associated with strep or staph TSS?
Staph
True or false: Pt’s with staph TSS are otherwise healthy w/ no pre-existing skin infections?
True
Which pathogen of TSS is associated with tampon use?
Staph
What pathogen is a burrowing mite that is the most serious of the mites, a close relative of ticks, and leads to scabies, crusted scabies, mange, and seven year itch?
Sarcoptes scabiei
What is the morphology of Sarcoptes scabiei?
Small mite w short legs
Is a male or female Sarcoptes scabiei fertilized on the skin surface, burrows into the epidermis, and completes its life cycle in 5 weeks then dies in the burrow?
Female
Does a male or female Sarcoptes scabiei have a shorter life span and remains on the skin surface or produces a shallow burrow?
Male
Where are the eggs of Sarcoptes scabiei laid and how soon after incubation do larva emerge?
Under the skin
Larva emerge after 4 days
How long after Sarcoptes scabiei hatch do adult mites develop?
2 weeks
How long after someone is infested with Sarcoptes scabiei does it take for sxs (itching) to develop?
First infestation = weeks
Re-infection = 24 hours
What causes the majority of clinical issues (intensely pruritic eruption that is worse at night) with Sarcoptes scabiei?
Burrowing
What pathogen has an incubation period of 1 month and results in crusted scaling lesions that are intensely pruritic, with lesions having hundreds to thousands of mites?
Sarcoptes scabiei- crusted (Norwegian) scabies
What population is readily infected w/ crusted scabies?
HIV
What condition is similar to Norwegian scabies, but the lesions may be blood filled?
Pediatric scabies
How is scabies most commonly spread?
Direct person contact (STI)
Crowded living conditions
How are scabies identified?
Apply mineral oil, scrape lesion and visualize microscopically (look for whole mite or mite parts, eggs, or fecal pellets in burrows)
What is the pathogen responsible for pubic lice/ “crabs”?
Phthirus pubis
How does Phthirus pubis infected the pubic area?
Nits (eggs) cemented to hair, adults bite and feed in pubic area
How is Phthirus pubis transmitted and identified?
Transmitted by sexual contact or contaminated bedding
ID by visualizing louse or nit
What is the pathogen responsible for pediculosis?
Pediculus humans
What pathogen is a vector for epidemic typhus?
Pediculus humans
What pathogen is a nit cemented to a fiber in clothing or human hair and has an egg-to-egg cycle that takes about 3 weeks?
Pediculus humans
If a pt presents with bite irritation (parasite is bloodsucking), “vagabonds disease” (years of infestation) and darkened, thickened skin, what should you be concerned about?
Pediculus humans/ pediculosis
How is P. humanus spread?
Easily- crowded conditions, conditions where clothing cannot be changed often
What pathogen is 1-4mm in length, laterally compressed, and has short spikes on its legs that allow attachment to the host?
Pulex irritans (human flea)
What does Pulex irritans need to survive?
Blood (it is a parasite)
What do Pulex irritans inject during a blood meal?
Saliva that initiates an allergic response
What is the main manifestation of an infection w Pulex irritans?
Rash
What is a tick-borne disease via a brown dog tick (AZ)?
Rocky Mountain Spotted Fever
What pathogen is responsible for Rocky Mountain Spotted Fever?
Rickettsia rickettsii
What pathogen is described as G-, obligate intracellular, non-motile, and pleomorphic and can cause a potentially fatal disease if not tx in the first few days of sxs?
Rickettsia rickettsii
During what time of year is Rocky Mountain Spotted Fever seen more frequently?
Summer months (peak in June and July)
If a pt presents w hx of a painless bite and didn’t notice sxs until 2-14 days post bite, what disease should you be concerned about?
Rocky Mountain Spotted Fever
What parts of the body does Rickettsia rickettsii invade?
Endothelial cells that line blood vessels
What early sxs and sudden onset sxs are seen with Rocky Mountain Spotted Fever?
Early sxs are non-specific
Sudden onset sxs = fever, HA
What 2 types of rash are seen with Rocky Mountain Spotted Fever?
- small, flat, pink non-itchy spots (macules)
2. red to purple spotted petechial rash +/- pinpoint hemorrhages
Which type of Rocky Mountain Spotted Fever rash will likely be seen on wrists, forearms, ankles and spreads to trunk, palms and soles 2-5 days post infection?
small, flat, pink non-itchy spots (macules)
Which type of Rocky Mountain Spotted Fever rash will likely be seen after 6 days post infection, and is a sign of late infection/ severe disease?
red to purple spotted petechial rash
If you suspect a pt is infected with Rocky Mountain Spotted Fever, do you wait to treat until receiving laboratory confirmation?
No- most successful if tx initiated w/i first 5 days
Why is Rocky Mountain Spotted Fever a difficult disease to deal with?
Similarity to other diseases
Difficult to detect until disease is in late stages
Why are diagnostic tests not a good option for Rocky Mountain Spotted Fever?
Detectable antibody titers are not visible for 7-10 days post infection
What is the gold standard for dx of Rocky Mountain Spotted Fever?
Indirect immunofluorescence w/ a R. rickettsii antigen (2 samples 2-4 weeks apart)
What pathogen is responsible for African sleeping sickness?
Trypanosoma brucei
What pathogen is responsible for Chagas disease?
Trypanosoma cruzi
What pathogen is responsible for Leishmaniasis?
Leishmania spp.
What disease is prevalent in Mexico, Central America, and South America, is considered a neglected parasitic infection (NPI) by the CDC in the US and is associated w survivors that typically exhibit altered organ function?
Chagas disease
What is the vector for Chagas disease?
Triatomine bugs (“kissing bugs”)
What parasitic protozoan is transmitted through feces of the triatomine bug, blood transfusions, organ transplants, and congenital?
Trypanosoma cruzi
What happens once the trypomastigote (T. cruzi) enters near the inoculation site?
It differentiates into amastigotes
What happens to the amastigotes (T. cruzi) once differentiated into?
Replicate by binary fission in cells, differentiate, and release into circulation to rupture host cells
What are the key characteristics of the acute stage of Chagas disease?
Asx to mild manifestation
Non-specific signs/ sxs, +/- Chagoma
Romanas sign- swelling of eyelid near entry site
What are the key characteristics of the chronic stage of Chagas disease?
Pseudocysts of amastigotes in cells (muscles and nerves affected, degeneration and necrosis)
Chronic inflammation
Cardiac > intestinal complications
How long can the infection with Chagas disease be asx?
Years, or even for life
How is Chagas disease diagnosed?
Parasite under microscopy- blood smear (acute) or biopsy (chronic)
Serological tests
What is involved with prevention and control of Chagas disease?
Insecticides/ housing improvements Bednets Screening of blood donors Testing of organ, tissue, cell donors Screening of newborns/ children of infected mothers for early dx/ tx
Viral infection that causes infectious mononucleosis (IM)?
EBV
EBV is linked to what form of cancer?
Burkitt’s lymphoma
IM is a B or T cell infection?
B cell. Induces polyclonal expansion of lymphocytes
Sore throat, symmetrical lymphadenopathy, and fever +/- hepatomegaly is concerning for what?
IM
Downey cells (atypical lymphcytes) appear in the circulation for pt’s infected with what disease?
IM
In IM does B cells or T cells generate most of the pt’s sx?
T cells
Transmission pattern for EBV?
Person to person
Peak incidence of EBV causing IM?
17-25 yrs
Early infection w/ EBV in a pt from regions of Africa is concerning for what?
Burkitt’s Lymphoma
Presence of what type of antibodies are help dx EBV IM?
Heterophile AB
Why might the monospot test give a false negative?
Age-specific reactivity. Less useful in kids so use IgM anti virus capsid antigen serology
When treating IM pt with penicillin you must warn them about?
Penicillin reaction rash
Which virus, CMV or EBV, DOES NOT produce heterophile antibodies?
CMV
What populations are most at risk for CMV?
IMC, transplant pts, infections occurring during pregnancy
Does MMR provided lifelong immunity to mumps for all recipients?
Not for egg or neomycin sensitive pts. Pts that have been vaccinated are still getting the disease.
How is mumps controlled?
Vaccination
Borrelia burgdorferi is the pathogen for what disease?
Lyme disease
Pt presents with erythema migrans/red bulls eye rash. What stage of lyme disease are you suspecting?
Stage 1: Acute localized disease
Flu sx, brief asymmetric arthritis attaches and/or secondary annular skin lesions may be concerning for what stage of lyme disease?
State 2: Subacute disseminated disease
Chronic lyme disease is easier or harder to treat?
Hard the further the disease process
Chronic lyme disease (stage 3) is associated with primarily what sx?
Musculoskeletal.
Arthritis attacks become more persistent and last long
What general location of the US has the highest reported cases of lyme disease?
NE
Vector for lyme disease?
Tick vector (deer or black-legged)
Ticks exhibit what type of behavior?
Questing behavior
Lyme disease reservoir hosts?
Small mammals and birds
What form of the black legged tick causes large portion of infections in humans?
Nymphal
Serology test for lyme disease?
EIA w/ western blot follow up if positive (positive by 4th week of infection)
What disease states might cause false positive on lyme disease serology test?
Syphilis, mono, SLE, RA, oral infection w/ spirochetes
How can you prevent lyme disease?
Control and avoidance of vector contact (Deet, tick checks following outdoor activity)
Post TX Lyme Disease Syndrome is chronic or will improve with time?
Most should improve with time
Source of Hep A and Hep E?
Feces
Route of transmission for Hep A and E?
Fecal-oral
Are Hep A and E a chronic infections?
No
A= infectious
Source of Hep B, C, and D?
Blood/blood-derived body fluids
B= serum
C= transfusion-associated
Route of transmission for Hep B, C, and D?
Percutaneous, permucosal
Is Hep B a chronic or acute infections?
Chronic
True or false: Hep C and D are chronic infections?
true
Hep A will have IgM antibody on ELISA, True or False?
True
HAV prevention measures? (5)
- Hand washing
- Avoidance of contaminated food/water
- Post exposure prophylaxis
- Vaccine
- Education
Which Hepatitis virus is infectious cause of primary hepatocellular carcinoma?
Chronic HBV
Presence of double walled Dane particle is indicative of infectious or non-infectious form of Hep B?
Infectious
Largest reservoir for HBV?
Chronic hepatitis pts
Are HBeAg positive pts at risk of transmitting HBV infection?
Yes
What are newborns vaccinated against HBV?
90% of infections become chronic
IgG and anti-HBc indicated past or present HBV infection?
Past
Rapid Hepatitis virus test detect what type of HBV antigen?
Surface
Is HBV a self limited disease for most adults?
Yes, no specific curative tx exisits
Do tx for chronic HBV result in a cure?
No only inhibit viral replications, prevent liver damage progression
True or false, Subunit vaccine is available for HBV?
True
True or false: immunoglobulin is available for HBV prophylaxis?
True
Which form of hepatitis requires presence of chronic HBV and superinfection?
HDV
HDV will increase or decrease the severity of HBV?
Increase
Pts with chronic HBV are a reservoir for what disease?
HDV
Positive delta antigen on ELISA is indicative of what hepatitis infection?
HDV (but must also have active HBV)
True or false: HBV vaccine will protect against HBV and HDV?
True
Form of hepatitis associated with needle sticks and M/M unprotected sex?
Hep B
Form of hepatitis that most often occurs post transfusion?
Hep C
Establishment of chronic infection is the hallmark for what form of hepatitis?
HCV
True or false HCV often does not progress to cirrhosis and liver failure
False. It often does!
Serologic tests will show increased or decreased anti-HCV over time?
Increased
Acute HCV will most often develop into what disease?
Chronic
Factors that promotes HCV infection progression? (5)
- Alcohol use
- Infection at age ? 40
- Male sex
- Hep B co-infection
- HIV co-infection
What is dx of HCV difficult?
chronic state and acute phase viremic patients often escape detection
TX for HCV ?
Direct acting antiviral agents (DAAs) , possibly curable
Are combination regiments the same for all 6 HCV genotypes?
No, vary with virus genotype
If HBV and HVC co infection which form usually dominates and is thus treated first?
HCV
DAA tx that eliminates HCV will:
- Eliminate HBV?
- Activate HBV?
Activate
True or false: because HCV tends to suppress HBV activity, we are not sure how often the two viruses are found together?
True
HCV prevention? (2)
- Blood screening
2. Effect to ID compensated, unrecognized infections
What are the two leading causes for liver transplant?
Cirrhosis and hepatocellular carcinoma
Will life transplant be curative for HBV and HCV confection?
Yes
Is a liver transplant pt at risk for recurrent infection?
Yes, if no edu/lifestyle change AND b/c IMC
Pt presents w non-specific sore throat and swollen lymph glands mimicking a mono-like condition… what are you concerned for?
Initial HIV infection
When is HIV in a period of high transmission risk?
Early stages when pt unaware they are HIV- infected (high levels of virus in circulation)
All pts with HIV are considered what?
Life-long carriers and continually infectious
When is AIDS (stage 3 HIV) diagnosed?
What are CD4 T cell levels at?
When severe damage to immune system is evident
CD4 T cells < 200 uL
AIDS defining conditions emerge as what declines?
Immune system function
What disease is associated w/ Kaposi’s sarcoma, pneumocystis pneumonia, MAC infection, severe CMV disease, cryptosporidiosis, and candidiasis?
AIDS
What defines the “fast” HIV disease course class?
3 years or less to AIDS
What defines the “intermediate” HIV disease course class?
AIDS emergence ~ 1 decade post infection
What defines the “long term non-progressors” HIV disease course class?
> 10 yrs (under 5% of cases)
What pathogenic agents has the following characteristics:
- Human retrovirus
- RNA genome
- Enveloped
- Reverse transcriptase
HIV/ AIDS
AIDS is now considered to be a probable what that has entered human populations?
Zoonosis (animal disease)- contact via primates/ bushmeat
What has sequencing of the HIV/ AIDS viral genome revealed?
A focus in African and entry of HIV into human populations several times
How is HIV/ AIDS most commonly spread?
STIs
What are 3 myths about HIV?
Polio vaccine = source of HIV-1
Pt zero
Deliberate spread
How can HIV-1 become a latent disease?
Entry into T/B memory cells (reverse transcription)
How does HIV exhibit cytopathic effects?
TH cell loss = immunosuppression
Formation of “swarms”
mechanism of viral killing uncertain
Is you notice Gohn lesions and ipsilateral calcified hilar lymph nodes on CXR, what is this concerning for?
Ranke complex, concerning for healed primary TB
What are the 3 most common HIV routes of transmission?
- sexual contact
- parenteral (IV drug use, needle sticks)
- perinatal
Is HIV-1 or HIV-2 more common worldwide?
Is HIV-1 or HIV-2 less easily transmitted?
HIV-1 = worldwide, HIV-2 = W Africa
HIV-2 less easily transmitted, exhibits slower progression to AIDS, resistant to NNRTIs
What is the progression pattern of HIV?
- Infection
- Free replication
- Pt ab response
- Latent virus changes and no longer immune
What is the goal of HIV tx?
Keep virus @ low levels and keep from killing CD4 lymphocytes
What 2 steps are used for dx of HIV? (HIV ab)
- EIA screen (general)
2. Western blot
What designates an HIV + test on Western blot for CDC?
2 cross-reacting bands
What is the role of direct tests for HIV?
Determine how much virus is present
Protect blood supply (donated blood screened)
Which direct test is able to detect and quantify the HIV virus?
Nucleic acid test (NAT)
Why should you do direct tests and not just AB tests for HIV?
Early disease may not have ab yet
What is the general tx for HIV but what is important to know about it?
Tx = combo of antiviral agents, but NOT curative
What 3 types of antiviral agents are included in combo treatment for HIV?
Reverse transcriptase inhibitors
Protease inhibitors
Fusion-penetration inhibitors
What is the role of viral load tests for HIV pts?
Tests amount of HIV in blood
Watch trend of counts
Run frequently if early in disease
Why does HIV impact cognitive function?
Neuron damage
What is the best control method for HIV?
Prevention/ education
Anti-retroviral therapies drive virus levels to undetectable levels… why is this important?
Undetectable = un-transmissible
What are new strategies for ending HIV transmission?
PrEP if at risk
Early ID/ therapeutic tx
How is malaria transmitted?
Plasmodia from salivary glands of Anopheles female mosquito
What are the Malaria important species, and which are the 2 most common?
Plasmodium vivax (most common) P. falciparum (most common) P. malariae P. ovale P. knowlesi
What are the 2 phases of malaria life cycle, contributing to its ability to evade host defenses?
Human phase and mosquito phase
How is the malaria life cycle initiated in humans?
Injected of Plasmodium sporozites (motile forms) in saliva
How do sporozoites divide once they migrate to the liver?
Asexual division = schizogony
What is the name of the life cycle form released from the schizogony phase of the malaria life cycle?
Merozoites
What stage of the malaria life cycle is the vaccine target?
Sprorozoites
What do merozoites infect?
Other liver cells or RBCs (erythrocytic cycle)
Once in the RBC, merozoites enlarges and undergoes a differentiation into what?
Ring trophozoite (uninucleate)
As trophozoites age, what can they develop into?
Amoeboid trophozoites
In the malaria life cycle, a single nucleus can also divide to produce what?
Schizont
Erythrocytic schizonts are multinucleated cells that produce what?
Erythrocytic merozoites
After an infected RBC ruptures and merozoites escape to invade new cells, what happens?
Schizogony begins again or gametogony (sexual cycle) is initiated
What leads to sexual reproduction within the mosquito?
malaria life cycle
Erythrocytic merozoites develop into gametocytes, which are then taken up by mosquito
Sporozoites produced in the mosquito and traveling to the salivary glands of the mosquito contribute to treatment difficulty?
Exchange of DNA allowing the mosquito to change and gain drug resistance
What does the malaria organism consume?
Hemoglobin
Release of pyrogenic waste from rupture of RBCs travel to hypothalamus and cause what?
Increased thermal set point = fever and chills (sxs)
If a pt presents with episodes of 1-2 hours of severe shivering and high fever following it, what is the cause? (Malaria)
TNF release (inflammation) after pyrogen travels to hypothalamus
What is one of the first signs of malaria?
Anemia due to RBC destruction
Why is malaria difficult to treat?
Mimics other diseases
What 2 things can provide a pt with malaria resistance? What forms are they specifically resistant to?
Sickle cell anemia (all forms)
Lack of Duffy antigen (P. vivax)
What is the malaria vaccine and what is the issue with it?
RTS, S (Mosquirix)
Low efficacy
What are the reservoirs for malaria?
Humans and simians
What role will climate change play in the spread of malaria?
Increasing land mass and population being exposed to disease
Organism can survive in areas it didn’t used to be able to
Plasmodium vivax is aka what?
Vivax malaria, benign tertian malaria
Why is Plasmodium vivax is seldom fatal?
Infects young erythrocytes (receptor no longer available once erythrocyte ages)
Pt prevents with relapse of malaria infection 3-5 years after initial disease. What organism are you concerned about and what is the reason for the relapse?
Plasmodium vivax
Activation of liver hypnozoites
If Plasmodium vivax is microscopically evaluated, what should you see?
Enlarged infected RBCs with Schuffner’s dots
How is infection with Plasmodium vivax controlled?
Protection from mosquitos (nettings, insecticides, repellants)
What malaria organism has the capability to infect any age RBC?
Plasmodium falciparum (malignant tertian malaria)
Rapid multiplication and high parasite numbers lead to what sxs?
High fever/ Blackwater fever
Pt presents w/ high levels of free Hgb in urine. What are you concerned about and what might this lead to?
Blackwater fever
Concerned for autoimmune rxn w destruction of kidney tissue
RBCs infected with Falciparum malaria stick to capillary linings leading to what?
Capillary obstruction
Pt presents with cold skin temp but high internal malaria. What should you be concerned about?
Algid malaria (releated to Plasmodium falciparum)
How can Plasmodium falciparum be distinguished from Plasmodium vivax?
Plasmodium falciparum is non relapsing due to lack of hypnozoite stage and absence of Schuffners dots on microscopic eval
Pt presents w/ hx of mosquito bite and signs of necrosis, hemorrhages, extreme fever, mania, convulsions, and is at risk of death. What is the infecting species and what type of malaria are you concerned about?
Plasmodium falciparum
Cerebral malaria
Gastric falciparum malaria from the Plasmodium falciparum species leads to what sxs?
Frequent vomiting
On microscopic eval of blood of a malaria infected pt you see erythrocytes with double or multiple ring stages, crescent shaped gametocytes, and Maurer’s clefts. What organism are you concerned about?
P. falciparum
On microscopic eval of blood of a malaria infected pt you see young trophozoites and gametocytes but not schizonts in the periphery. What infecting organism are you concerned about?
P. falciparum
How is P. falciparum controlled?
Protection from mosquitos (nettings, insecticides, repellants)
What malaria organism has the following characteristics:
Infects older RBCs
Paroxysms every 4th day
Zoonotic from primate reservoirs
P. malariae
On microscopic eval of blood of a malaria infected pt you see trophozoites (basket and band shaped) and schizonts (rosette shaped). What infecting organism are you concerned about?
P. malariae
What malaria organism has the following characteristics:
Similar to vivax malaria
Relapses common
Common to W coast of Africa
P. ovale
What malaria organism has the following characteristics:
Zoonotic
May be life-threatening if heavy parasite burden
Common to SE Asia
P. knowlesi
Why is medication targeting Duffy antigen becoming less effective?
Increasingly independent binding to Duffy antigen
What is the main cause of drug resistance for malaria organisms?
Efflux pumps
What is the causative agent of Babesiosis (Nantucket island fever)
Babesia microti
What does Babesia microti infect?
RBCs
When do you have increased transmission of Babesia microti?
Warmer months/ summer
Lack of ability to test for Babesia microti in the blood leads to issues why?
Transmission through blood donation
What is the vector for Babesia microti?
Deer tick
Pt presents w small pinpoint lesions and are diagnosed w anemia. What organism should you be suspicious of?
Babesia microti
Babesia microti often presents with a co-infection of what disease?
Lyme disease
If under microscopic examination you note a “cross like” morphology in RBCs, what infecting organisms should you be concerned for?
Babesia microti
How is infection with Babesia microti controlled?
Insect repellants when outdoors
How did water treatment plants affect infection with polio?
Shifted from infants getting infected (fewer complications) to children getting infected
What disease affects the brain stem and cerebellum?
Rabies
What disease affects the cerebral cortex and cerebellum?
Creutzfeldt-Jakob encephalitis
What is the only disease that you vaccinate after exposure for?
Rabies
What disease affects the anterior horn cells and bulbar motor nuclei?
Poliomyelitis
What disease is associated with asymmetric flaccid paralysis?
Poliomyelitis
What causes asymmetric flaccid paralysis seen with poliomyelitis?
Destruction of motor neurons in spinal cord
What is the virus responsible for poliovirus?
Picorna virus
What are the 5 main clinical syndromes of the polio virus infection?
- Inapparent infection (most common)
- Abortive illness
- Nonparalytic poliomyelitis
- Paralytic poliomyelitis
- Post polio syndrome
What is the rarest/ more severe manifestation of the polio virus infection?
Paralytic poliomyelitis
What device is used for pts with paralytic poliomyelitis to continue breathing?
Iron lung
What polio syndrome is associated with muscle weakness, pain and fatigue in paralyzed polio pts?
Post polio syndrome (30 yrs post)
Only in paralyzed pts
In a pt with post polio syndrome, has the latent polio virus returned?
No, remaining motor units of CNS react to overuse and fail
How can polio be prevented?
Inactivated polio vaccine (IPV) (Salk)
Live polio vaccine, trivalent oral polio vaccine (OPV)
Does the inactivated polio vaccine prevent infection?
No, prevents disease/ paralysis (not infection)
Why is the live polio vaccine (OPV) no longer used in the US?
Possibility for back mutation to wild type
Why is it important to continue to vaccinate against polio?
The polio virus is still present in some countries
What is the cause of the newest/ uncontrolled strain of polio?
Circulating vaccine-derived polioviruses (cVDPVs)
What arbovirus is the most concerning in the US and how is it transmitted?
West Nile virus
Vector= mosquito, tick
What is the reservoir for West Nile virus?
Animals
Are humans active hosts for arbovirus (West Nile virus)?
No (dead end hosts)
What is the most concerning agent of disease for arbovirus?
Flavivirdae group (yellow fever group)
What is important in the treatment/ prevention of arbovirus?
Break chain of transmission
Pt presents w fever, HA, vertigo, photophobia, nausea, vomiting, confusion/ personality changes, focal/ general seizures. What are you concerned for?
Arbovirus
What serious complication is caused by WNV?
Encephalitis
What population is typically affected by WNV?
Older pts
What time of year is WNV most prevalent?
Summer/ fall (higher mosquito activity)
Does WNV have the potential to cause viral encephalitis?
Yes
What test is used for the dx of WNV?
MAC-ELISA (look for IgM antibody)
In pts with yellow fever, dengue, Japanese encephalitis St Louis encephalitis viruses, what should you beware of when performing tests such as MAC-ELISA?
Antigenic cross reactions
Vaccination against yellow fever and/ or Japanese encephalitis may induce what?
Long-lasting positive IgM titers (for 9 mos past vaccine)
travel hx important
What test is best for dx of Zika?
RT-PCR
For all arboviruses besides Zika, what is the best dx test?
IgM ELISA
How is infection w arbovirus prevented?
Interrupt chain of transmission
What is the major concern w Zika virus?
Teratogenic potential and GBS
What are most US cases of Zika virus associated with?
Travel
How can Zika virus be prevented?
Mosquito avoidance and pt edu (including potential to transmit as STI)
What is the target of rabies disease?
Salivary glands
Only touch with rabid animal can cause what?
Cryptic rabies
What affected organism exhibits a “furious” excitatory phase?
Dogs only
Humans experience anxiety and apprehension hydrophobia
Pt presents w mild fever, pharyngitis, HA, and abnormal sensations such as pain and burning. What should you be concerned for?
Rabies
What phase of rabies is characterized by coma, hypotension, and possible death?
Paralytic phase
How is rabies dx’d?
Exposure to bite + sxs
In what case do you always treat/ should you be especially cautious for with regards to rabies?
Contact w a bat
Microscopy shows a “bullet shaped” organisms. What should you be concerned about?
Rabies
What “tx” for rabies has failed as often as it has succeeded?
“Milwaukee” protocol
How is rabies prevented in animals?
Prophylactic vaccination in companion/ herd animals
How is rabies treated in humans?
Vaccine (HDCV) + hyperimmune serum after contact w reservoir animal
What are the 2 broad categories of CNS infections?
Meningitis and encephalitis
What CNS infection is defined as inflammation resulting from an infection within the subarachnoid space?
Meningitis
What CNS infection is defined as inflammation in the parenchyma?
Encephalitis
What organism-dependent skin complication can occur from CNS infections?
Abscess formation
What time frame defines acute v chronic meningitis?
Acute = hours to several days Chronic = ≥ 4 weeks (w over exaggerated immune response)
What is the danger with respiratory pathogens?
Can enter blood and cause CNS infection
Why has the cause of bacterial meningitis infections shifted from H. influenzae to S. pneumoniae?
Vaccine against H. influenzae
S. pneumoniae is cause of resp infections which lead to CNS infections
Why has the incidence of meningitis declined significantly over time?
Vaccines
Screening of pregnant women for GBS (group B strep)
What can manifest as an “aseptic” case of meningitis (and classified as virus) due to difficulty in making a positive ID of pathogen?
Bacterital meningitis
Which type of meningitis is usually caused by organisms able to colonize the resp tract?
Community acquired
Which type of meningitis results after iatrogenic procedures or in patients with altered immune status and often GI/ skin pathogens?
Hospital acquired
What is step 1 in pathogenesis of bacterial meningitis?
- Entry into blood stream
- Penetration of BBB
- Release of inflammatory cytokines
- WBC diapedesis into CSF
- Increased permeability of BBB
- Exudation of serum
- Edema, increased intracranial pressure, altered BF
Mucosal colonization
What is step 2 in pathogenesis of bacterial meningitis?
- Mucosal colonization
- Penetration of BBB
- Release of inflammatory cytokines
- WBC diapedesis into CSF
- Increased permeability of BBB
- Exudation of serum
- Edema, increased intracranial pressure, altered BF
Entry into blood stream
What is step 3 in pathogenesis of bacterial meningitis?
- Mucosal colonization
- Entry into blood stream
- Release of inflammatory cytokines
- WBC diapedesis into CSF
- Increased permeability of BBB
- Exudation of serum
- Edema, increased intracranial pressure, altered BF
Penetration of BBB
What is step 4 in pathogenesis of bacterial meningitis?
- Mucosal colonization
- Entry into blood stream
- Penetration of BBB
- WBC diapedesis into CSF
- Increased permeability of BBB
- Exudation of serum
- Edema, increased intracranial pressure, altered BF
Release of inflammatory cytokines
What is step 5 in pathogenesis of bacterial meningitis?
- Mucosal colonization
- Entry into blood stream
- Penetration of BBB
- Release of inflammatory cytokines
- Increased permeability of BBB
- Exudation of serum
- Edema, increased intracranial pressure, altered BF
WBC diapedesis into CSF
What is step 6 in pathogenesis of bacterial meningitis?
- Mucosal colonization
- Entry into blood stream
- Penetration of BBB
- Release of inflammatory cytokines
- WBC diapedesis into CSF
- Exudation of serum
- Edema, increased intracranial pressure, altered BF
Increased permeability of BBB
What is step 7 in pathogenesis of bacterial meningitis?
- Mucosal colonization
- Entry into blood stream
- Penetration of BBB
- Release of inflammatory cytokines
- WBC diapedesis into CSF
- Increased permeability of BBB
- Edema, increased intracranial pressure, altered BF
Exudation of serum
What is step 8 in pathogenesis of bacterial meningitis? 1. Mucosal colonization 2. Entry into blood stream 3. Penetration of BBB 4. Release of inflammatory cytokines 5. WBC diapedesis into CSF 6. Increased permeability of BBB 7. Exudation of serum 8.
Edema, increased intracranial pressure, altered BF
What is the most common pathway for a pathogen gaining access to the CNS?
Invasion of the bloodstream and seeding of the CNS
Besides invasion of the bloodstream and seeding of the CNS, what are the other 2 pathways for a pathogen gaining access to the CNS?
Retrograde neuronal pathway
Direct contiguous spread
What allows fluid, WBCs and other immune components to enter the blood during a CNS infection?
“Leaky” blood vessels
What is the classic triad of sxs for CNS infections?
Fever, HA, neck stiffness
What would you expect to see with CSF glucose levels in a pt with a CNS infection?
Decreased; organism uses as energy source
Neonatal meningitis can be caused by what factors?
Neonatal or maternal factors
What are the most important signs/ sxs seen with neonatal bacterial meningitis?
Bulging fontanelle, high pitched cry, hypotonia, paradoxic irritability
What is paradoxic irritability seen with neonatal bacterial meningitis?
Quiet when stationary and crying when held
How can neonatal bacterial meningitis be classified that differentiates it from meningitis seen in adults?
Hyperthermia +/- GI disturbance
What are the predominant agents of neonatal bacterial meningitis, and are they G+ or G-?
Streptococcus agalactiae (G+) (GBS) E. coli (G-) Listeria monocytogenes (G+)
Screening pregnant mothers for GBS and routine abx prophylaxis for culture + women contributes to what?
Prevention of neonatal bacterial meningitis
Does a child who survives neonatal bacterial meningitis have long term effects?
Yes, usually permanent defects
What is the most common cause of neonatal bacterial meningitis?
Streptococcus agalactiae (GBS)
Which causative agent of neonatal bacterial meningitis will display gray-white colonies with a narrow zone of beta-hemolysis on microscopy?
S. agalactiae (GBS)
When do most cases of neonatal bacterial meningitis caused by S. agalactiae occur?
Transmitted during delivery (remainder acquired postpartum)
Capsular polysaccharide, hyaluronidase, collagenase, and hemolysin are virulence factors for what pathogen?
(dangerous bc neonates are IMC)
S. agalactiae (GBS)
When can S. agalactiae (GBS) be seen in adults?
IMC
With early onset neonatal bacterial meningitis, are maternal obstretric complications common or uncommon?
Common
When do sxs develop with with early onset neonatal bacterial meningitis?
During first 5 days of life
What type of neonatal bacterial meningitis is characterized by bacteremia, pneumonia, and meningitis?
Early onset
What type of neonatal bacterial meningitis leads to systemic effects (bone/ joint infections, bacteremia w meningitis) and is often fatal?
Late onset
How is infected by S. agalactiae diagnosed?
Lab tests detect CAMP factor (only works 25% of the time)
How is S. agalactiae definitely diagnosed?
Isolation from blood, CSF
Source of E. coli (causing bacterial meningitis) is rectal colonization of mother’s vagina and NOT what?
An endogenous infection
What is the morphology of E. coli?
G- encapsulated bacillus
What is the most common cause of bacterial meningitis, is most common agent in elderly, and is most common with recurrent meningeal infections?
S. pneumoniae
What is the morphology of H. influenzae (causing bacterial meningitis)?
Non-motile, G- coccobacillus
What causative agent of bacterial meningitis displays a usual pattern of several days of mild antecedent infection followed by deterioration, signs and sxs of meningitis?
H. influenzae
What is the morphology of L. monocytogenes (causing bacterial meningitis)?
G+ motile coccobacillus, non-fastidious, facultative IC pathogen
What pathogen causing bacterial meningitis is common in foodstuffs?
L. monocytogenes
What temps allows survival of L. monocytogenes?
Low temps (freezer, refrigerator)
What pathogen is considered the “exception” because it is not commonly a resp infection and is more common in summer?
L. monocytogenes
What are the 2 primary virulence factors of L. monocytogenes?
Lipopolysaccharide-like surface component
Listeriolysin O
What virulence factor of L. monocytogenes has the following characteristics:
Antiphagocytic
Presumably responsible for induction of complement- depdendent hemolytic antibodies
Lipopolysaccharide-like surface component
What virulence factor of L. monocytogenes has the following characteristics:
Disrupts phagolysosome membrane
Inhibits antigen processing
Induces apoptosis
Listeriolysin O
Why is pathogenesis listeriosis dangerous in an IMC host?
IMC cannot eliminate = IC and EC multiplication and systemic disease
What are the 2 main clinical manifestations of listeriosis?
Sepsis and meningitis
If you note “tumbling” motility in hanging drop preparation of a pathogen, what should you be concerned for?
Listeriosis
How is listeriosis diagnosed?
DNA probe technology
What is the causative agent of meningococcal meningitis?
Neisseria meningitidis
What pathogen has a morphology that is fastidious, G-, kidney bean-shaped diplococcus and encapsulated?
Neisseria meningitidis
What is the most important serogroup of Neisseria meningitidis?
B
Who is the only reservoir for Neisseria meningitidis and what does infection require?
Humans
Close contact
Pt presents with a skin rash consisting of petechiae and pink macules that is widespread and erupted within hours. What are you concerned for?
Meningococcemia
If you note a + tumbler test in which the pts rash does NOT change color (aka is non-blanching), what should you be concerned about?
Meningococcal meningitis
Thayer-Martin agar is selective for what pathogen due to presence of antibiotics?
Meningococcal meningitis
Why don’t you give a group B vaccine with the A,C,Y,W135 vaccine on the same day in the same arm for prevention of Meningococcal meningitis?
Causes autoimmune rxn
What is the pathogenesis for reactivation/ secondary TB after progression from caseous lesions with necrosis?
Erode and discharge TB bacilli into bronchi (infectious) > erode blood vessel > hematogenous spread
What are the following used for?
Purified MTB protein derivative (PPD) in skin test
Boosters id’d by 2nd administration
BCG and NTM false pos
Serial screening programs to id latent TB
How does infection w MAC occur?
Infection through contaminated water or food
When can measles be especially severe?
Malnourished and/or vitamin A deficient persons
How does measles cause encephalitis?
Viremia, dissemination to other tissues by monocytes
What disease multiples in respiratory epithelium and lymph nodes?
Measles
What are the 4 stages of measles?
- Incubation period (10-14 days)
- Prodromal stage
- Rash
- Resolution
At what point do you have resolution of measles?
Rise in antibody titers, viremia stops, rash fades in same order it appears
Who are the only known hosts of measles?
Humans and monkeys
When is the measles vaccine given?
Initiation before school entry 1st dose = 15 mos 2nd dose = 4-6 yrs Monovalent measles vaccine if under 15 mos and high exposure likelihood Booster sometimes required
How is rubella treated?
Symptomatic relief
MMR
Intravenous immunoglobulin (IVIG) “last ditch effort” if exposure of non-immune mother in 1st trimester
How is continued spread of HSV halted?
Cell and humoral immune processes (disseminates if absent)
Besides spreading via contact with vesicular fluid, saliva, and secretions, how else can HSV be spread?
Asx shedding possible
Where does the chickenpox virus replicate?
Regional lymph nodes (4-6 days)
Liver and spleen (secondary viremia at 10-14 days)
Who gets the zostavax vaccine?
Pts over 50 yo
High potency vaccine
What is the treatment for parvovirus?
Sx relief (non-steroidal anti-inflammatory agents) Immunoglobulin available for anemia patients
What topical tx is used for folliculitis?
Clindamycin ointment or benzoyl peroxide
What type of spores are microconidia and macroconidia?
Asexual
What dermatophytid species is the most common cause of tinea capitis, fluoresces when examined with a wood lamp and produce hyphae, micro/ macroconidia (large, spindle shaped, multicellular, thick walled)?
Microsporum species
What are the 3 most common pathogens responsible for Tinea pedis, Tinea corporis, Tinea cruris, and Tinea unguium?
E. floccosum, T. mentgrophytes, T. rubrum
Also M. canis for corporis, cruris, capitis
How can recurrent furuncles be prevented?
Liquid soap containing chlorhexidine/ isopropyl alcohol and maintenance abx
How can impetigo and ecthyma be managed?
Hygiene, wash with soap and water, topical abx ointment
How is scalded skin syndrome treated?
Prompt dx and therapy w penicillinase- resistant anti-staph abx
If scalded skin syndrome is extensive, how should it be treated?
Treat as for burns
How is erysipelas treated?
Oral or IV abx targeted against most likely agent
Is type 1 NF mono or poly microbic?
Type 1 = poly
Type 2 = mono
Is type 1 or 2 “flesh eating bacteria”/ strep gangrene?
T2
Pt presents with a thick pink/ purple fluid filled bullae on leg that is not tender. What are you concerned for?
NF
What promotes split and invasion of nearby tissue in pts with NF?
Production of exotoxins and insoluble H2 gas
On surgery, infected muscle is dark red to black, non-contractile and does not bleed when cut. What should you be concerned for?
Clostridial myonecrosis
What is the treatment for Lyme disease?
Sx: amoxicillin or doxycycline for 10-21 days
What are the 4 possible courses of viral hepatitis?
- Subclinical and anicteric
- Typical acute icteric hepatitis
- Fulminant hepatitis
- Chronic hepatitis
Which course of viral hepatitis is associated with a high fatality rate?
Fulminant hepatitis
How is the subclinical and anicteric course of viral hepatitis recognized?
Seroconversion
What does the incubation period of typical acute icteric hepatitis course represent?
Dose dependent range
While the prodrome or pre-icteric phase of hepatitis is marked by fatigue, malaise, and anorexia, what is the icterus phase marked by?
Dark urine, jaundice, hepatomegaly, elevation of serum enzymes
What phase of the typical acute icteric hepatitis course includes disappearance of jaundice and other sxs?
Convalescent phase
What is the treatment for HAV?
Bed rest, reduction of activities, hydrated, good nutrition, avoid hepatotoxins
When should a pt with HAV be hospitalized?
If IV fluids needed or there is evidence of deteriorating liver function
What are the following HBV antigens associated with?
HBsAg
HBcAg
HBeAg
HBsAg- surface antigen
HBcAg- core antigen
HBeAg- surface antigen + pt infectious
HBV replicates almost exclusively where?
In the liver
Who is Colleen’s best friend?
Abbey <3
