LOs: 17-20 Flashcards
17 Epidemiology of STIs
20M new infections every year
Young ppl (15-24) account for 50%
Increasing resistance in Neisseria gonorrhea
Increasing sexual transmission of Hepatitis C in the MSM population
17 Syndromes of STIs in Females:
Causes:
No symptoms, but at risk for STD
Vaginitis/vaginosis
Cervicitis
Pelvic inflammatory disease
Genital ulcer or vesicle
Papular genital lesions
C. trachomatis (Ct), N. gonorrhoeae (Ng), HPV, HSV, HIV, HBV, others
Yeast (Y), bacterial vaginosis (BV), Trichomonas vaginalis (TV)
C. trachomatis, N. gonorrhoeae, HSV
C. trachomatis, N. gonorrhoeae, Enterobacteriaceae, anaerobic bacteria
HSV, Treponema pallidum, Haemophilus ducreyi
HPV, Molluscum contagiosum, condylomata (CL) (secondary syphilis)
17 Syndromes of STIs in Females:
Symptoms/Signs:
No symptoms, but at risk for STD
Vaginitis/vaginosis
Cervicitis
Pelvic inflammatory disease
Genital ulcer or vesicle
Papular genital lesions
None or subtle
Y: itching, redness, clumpy white discharge BV: amine odor, discharge
TV: itching, redness, discharge
Genital discharge, lower abdominal pain, intermenstrual bleeding
Can be subtle
Lower abdominal pain, deep dyspareunia, abnormal bleeding, tenderness on cervical motion
Painful or painless ulcers or vesicles + inguinal lymphadenopathy
HPV: usually subclinical; warts can be cauliflower- like
Molluscum: round, umbilicated papules CL: moist papules accompanied by generalized rash
17 Syndromes of STIs in Females:
Treatment:
No symptoms, but at risk for STD
Vaginitis/vaginosis
Cervicitis
Pelvic inflammatory disease
Genital ulcer or vesicle
Papular genital lesions
If known contact with STD, treat according to contact guidelines for index STD regardless of findings.
Otherwise, treat according to results of screening test.
Y: Topical imidazole or oral fluconazole
BV or TV: metronidazole
Give empirical treatment for Ct and Ng.
Treat with antibiotic regimen active against all major causes Hospitalize if (1) surgical emergency cannot be ruled out, (2) severe illness, (3) tubo-ovarian abscess, (4) failed oral therapy
HSV: acyclovir Syphilis: benzathine penicillin
HPV: liquid nitrogen, podophyllotoxin, others Syphilis: benzathine penicillin
17 Syndromes of STIs in Males:
Causes:
No symptoms, but at risk for STD
Urethritis
Epididymitis
Proctitis
Genital ulcer or vesicle
Papular genital lesions
C. trachomatis (Ct), N. gonorrhoeae (Ng), HPV, HSV, HIV, HBV, others
C. trachomatis (Ct), N. gonorrhoeae (Ng), HSV
C. trachomatis, N. gonorrhoeae, Enterobacteriaceae
C. trachomatis,
N. gonorrhoeae, HSV
HSV, Treponema pallidum, Haemophilus ducreyi
HPV, Molluscum contagiosum, condylomata (CL) (secondary syphilis)
17 Syndromes of STIs in Males:
Symptoms/Signs:
No symptoms, but at risk for STD
Urethritis
Epididymitis
Proctitis
Genital ulcer or vesicle
Papular genital lesions
None or subtle
Urethral discharge, dysuria, irritation of distal urethra or meatus
Unilateral scrotal swelling and/or tenderness
Anorectal pain (+ discharge), tenesmus
Painful or painless ulcers or vesicles + inguinal lymphadenopathy
HPV: usually subclinical; warts can be cauliflower- like
Molluscum: round, umbilicated papules CL: moist papules accompanied by generalized rash
17 Syndromes of STIs in Males:
Treatment:
No symptoms, but at risk for STD
Urethritis
Epididymitis
Proctitis
Genital ulcer or vesicle
Papular genital lesions
If known contact with STD, treat according to contact guidelines for index STD regardless of findings.
Otherwise, treat according to results of screening test.
Give empirical treatment for Ct and Ng.
Give empirical treatment for Ct and Ng, and consider use of agent effective against urinary tract pathogens.
If no indication of HSV, treat empirically for Ct and Ng.
HSV: acyclovir Syphilis: benzathine penicillin
HPV: liquid nitrogen, podophyllotoxin, others Syphilis: benzathine penicillin
17 Chlamydia trachomatis:
Biology & Life Cycle
- Type of pathogen
- Encodes…
- Development cycle involves…
Epidemiology
Classification
- Serovars
- Chlamydophila
Pathogenesis
- LGV vs. non-LGV
- Inflammation
- Type of infection
Diagnosis (4)
Treatment
- Normal
- Pregnant
- LGV
- Obligate intracellular pathogen, energy parasite
- Encodes major outer membrane protein
- Extracellular elementary body (EB) & replicative reticulate body (RB): EB prevents fusion of endosome w/ lysosomes, reorganizes into RB, synthesizes DNA/RNA/proteins, fills endosome w/ progeny, transforms into new EBs, infects new cells
Young, African Americans from the south (most asymptomatic)
- Serovars A-K: trachoma, cervicitis, PID, etc.
- Serovars L1-L3: lymphogranuloma venereum (LGV)
- Chlamydophila pneumonia: bronchitis & pneumonia
- Chlamydophila psittaci: zoonotic, pneumonia (psittacosis)
- LGV cause systemic infection in lymphoid tissues, non-LGV confined to mucosal epithelial cells
- Chronic inflammatory process leads to epithelial cell necrosis, fibroblast proliferation, & eventual scar tissue formation
- Casues prolonged & often subclinical infection
- NAAT
- Culture
- Immunofluorescence
- Serology
- Normal: Azithromycin (single dose) or Doxycycline (1 week)
- Pregnant: Azithromycin (single dose) or Amoxicillin (1 week)
- LGV: Doxycycline (3 weeks)
17 Chlamydia trachomatis:
Clinical Manifestations:
Infections in Males (5)
Infections in Females
Lymphogranuloma Venereum (LGV)
Infections in Newborns
- Urethritis: dysuria, clear/mucopurulent urethral discharge
- Epididymitis
- Reiter’s syndrome: arthritis, urethritis, & conjunctivitis
- Transmission to women
- Pharyngeal/rectal infection
- Urethritis, cervicitis: dysuria/pyuria, cervicovaginal discharge, abdominal pain, intermittent bleeding, dyspareunia, mucopurulent discharge
- Ascending infection: endometritis, salpingitis
- Bartholinitis: infection of Bartholin’s ducts
- Pelvic Inflammatory Disease (PID): ascends from vagina & cervix, lower abdominal pain, vaginal discharge, uterine bleeding, dysuria, dyspareunia, nausea, vomiting, fever
- Fitz-Hugh-Curtis syndrome: perihepatitis
- Biovar LGV (L1-L3)
- Small painless papule or ulcer at site of infection (penis or vagina)
- Enlarged painful lymph nodes
- Procitis: rectal damage, anal pruritis, mucoid rectal discharge, fever, rectal pain, tenesmus
- Conjunctivitis: major manifestation, watery purulent ocular discharge, 5-14 days after birth
- Pneumonia: gradually worsening nasal congestion & cough, 4-11 weeks after birth
17 Syphilis:
Pathogen
- Causative agent
- Characteristics
Epidemiology
- When most contagious
- Rates
Pathogenesis
- Infection
- Primary Syphilis
- Secondary Syphilis
- Tertiary Syphilis
Diagnosis
Treatment & Prevention
- Primary, Secondary, & Early Latent
- Late Latent & Tertiary
- Neurosyphilis
- Pregnant Women
- Treponema pallidum
- Treponemes: tapered, thin spiral rods, corckscrew locomotion
- Most contagious during primary & secondary stages
- Rates increasing in men, low socioeconomic, African American, heterosexual population in Southeast
- Infection
- Penetrates abraded skin & mucous membranes or transplacental
- Disseminates to lymphatics & blood stream within hours to days
- Primary Syphilis (Chancre)
- Lesions appear when concentration of ~107 per mg of tissue reached
- Median incubation: 3 weeks
- Secondary Syphilis
- Disseminated stage: greatest number of treponemes are present in body
- Treponemes seen in different tissues especially skin & lymph nodes
- Tertiary Syphilis
- Tertiary lesions consist of gummas, cardiovascular, & CNS disease (CNS invasion can occur at any time)
- Tertiary lesions result in irreversible tissue destruction
- History & physical exam
- Darkfield microscopy
- Serologic tests
- Non-treponemal tests: non-reactive w/ time, false positives (VDRL, RPR)
- Treponemal tests: should have standard non-treponemal test to guide decisions (FTA-ABS, MHA-TP)
- Primary, Secondary, & Early Latent
- Benzathine PCN G x 1 dose IM
- Doxycycline twice daily x 14 days (if PCN allergy)
- Late Latent & Tertiary
- 3 doses of Benzathine PCN G at 1 week intervals IM
- Doxycycline twice daily x 28 days (if PCN allergy)
- Neurosyphilis
- Aqueous crystalline PCN G IV x 10-14 days
- Pregnant Women
- ONLY PCN, desensitize if allergic
17 Syphilis:
Clinical Manifestations:
Primary Syphilis
Secondary Syphilis
Latent Syphilis
Tertiary Syphilis
Congenital Syphilis
PS
- Primary lesion develops at site of inoculation
- Initially a papule which then ulcerates
- Chancre is painless & has a clear base
- Associated w/ regional lymphadenopathy
- Can be seen in the penis, vagina, perianal/rectal area, & tongue
- Heals spontaneously
- Serologic tests may not be positive
SS
- Typically occurs 2-8 weeks after the disappearance of the chancre
- Rash & lymphadenopathy are the most common manifestations
- Rash will often but not always involve the palms & soles
- Condyloma lata (~10% of cases) are raised, enlarged lesions usually seen in warm, moist areas
- Mucous patches & alopecia may also be seen in ~5% of cases
- Liver & kidney involvement have been reported
- Serologic tests are usually highest at this stage
LS
- Lesions of primary & secondary syphilis resolve even w/o treatment
- At this stage, no lesions are apparent, although lesions of secondary syphilis may occur within the 1st year in 25% of cases
- Early latent: <1 year
- Late latent: ≥1 year
o Not thought to be infectious (except in pregnancy)
o Longer treatment required
TS
- ~30% of untreated pts progress to tertiary syphilis
- Endarteritis of the vaso vasorum of the aorta can lead to aortits & aneurysm formation (usually in the ascending aorta)
- Chronic inflammation of coronary arteries lead to narrowing/stenosis
- Gummatous syphilis is characterized by indolent, destructive lesions of the skin, soft tissue, & bony structures
CS
- Transmission occurs during any stage (higher in P&S)
- Infection can occur at any stage of the pregnancy
- Stillbirth, death soon after birth, physical deformities, neurologic complications
- Neonatal disease: usually premature, hepatic/splenic involvement, rash, pneumonia
- Late onset disease: bone malformation (saddle nose, saber shin), teeth malformation (Hutchinson’s teeth), & neurlogic deficits
18 Zoonoses:
Zoonotic Infections
Reservoir
Vector
Transmission
Severity
Control
Xenozoonosis
transmitted from animals to humans
where etiologic agent resides
medium (insect or other) transferring the etiologic agent between the animal reservoir and the human host
via ingestion, animal bites, or arthropod vectors
benign, low-grade infection
difficult due to existence of a mobile animal reservoir, easily spread
- Veterinary medicine
- Sanitary engineering
- Entomologic management
- Wildlife management
- Behavioral changes
transmission of infectious diseases from animal tissue transplantation
18 Factors Influencing Zoonoses:
Host (5)
Pathogen (5)
- Improved diagnostics
- Recreational travel to rural areas
- International travel
- Population displacement due to warfare
- Homelessness
- High population of reservoir host
- New reservoir or transmission cycle
- Global climate change
- Translocation of reservoir host & ectoparasties
- Newly emerged or recognized organism
18 Hantavirus:
Biological Characteristics
Reservoirs
Transmission
Virulence Factors
Pathogenesis
Symptoms
Diagnosis
Treatment
Prevention
BC
- Bunyavirus
- Spherical, nucleocapsid, enveloped, (-) RNA
- Have viral-specific transcriptase
- Buds from golgi w/ 2 glycoproteins
R
- Urine, saliva, & feces of rodents (esp deer mice)
T
- Breathing in aerosols containing infectious material
VF
- 2 envelope glycoproteins determine host range (esp endothelial cells)
- Multiply infect host, excreted, survive dehydration
P
- Lasting immunity
- Invades respiratory route, replicates, spreads to heart/gut/liver/kidney/CNS
- T cell infiltrate w/o necrosis
S
- Fever, headache, malaise, myalgia, diarrhea
- Death from pulmonary edema (respiratory failure) & renal shutdown
D
- History/exposure
- Viral RNA
T
- IV fluid, Dialysis
P
- Avoid rodent infested areas
18 Rabies Virus:
Biological Characteristics
Reservoirs
Virulence Factors
Pathogenesis
Symptoms
Diagnosis
Treatment
Prevention
BC
- Rhabdovirus
- 1 single-stranded (-) RNA, helical capsid, nucleocapsid, envelope
- Large bullet shaped virions
R
- Dogs, cats, pets, skunks, raccoons, foxes, bats
VF
- Neuronal tropism
- Targets ACh receptor
P
- Animal bites muscle, spreads to CNS, migrates to organs (esp salivary glands)
S
- Abnormal sensation at bite site
- Confusion, lethargy, paresis, increased salivation, irrational aggressive actions,
- Hydrophobia, seizures, paralysis, coma, encephalitis, death
D
- History
- Anti-rabies IgM, IgG
- Nuchal skin biopsy, saliva testing
- Confirmed in suspected animal by direct fluorescent antibody test of brain tissue
T
- Post-exposure rabies prophylaxis (PEP): wound cleansing, human rabies immune globulin (HRIG), HDCV
P
- Pre-exposure immunization w/ HDCV
18 Rickettsia rickettsii:
Biological Characteristics
Reservoirs
Transmission
Most Common Disease
Virulence Factors
Pathogenesis
Symptoms
Diagnosis
Treatment
Prevention
BC
- Rickettsiaceae
- Obligate intracellular pathogens
- Too small to gram stain but gram(-) structure
R
- Ticks of Dermacentor species
T
- Arthropod vectors (tick bite)
- Transovarial transmission from femal eto offspring
- Ticks feeding on small mammals
MCD
- Rocky Mountain Spotted Fever (throughout North & South America)
VF
- Direct actin reorganization (filopodia enhances spread)
- Phospholipases, proteases, and membrane peroxidation result in host cell damage
- Energy parasites
P
- Introduced by bite of adult tick (or crushing)
- Spread via lymph/blood
- Invades many mammalian cells but mainly vascular endothelium
- Lysis of endothelial cells leads to rupture of capillaries & small vessels
S
- Rash localized to extremities
- Fever, malaise, severe frontal headache, myalgia and vomiting
- Abdominal pain, diarrhea, conjunctivitis, mental confusion, meningitis, respiratory difficulties, renal
dysfunction, and/or myocarditis
- Lysis of endothelial cells leads to endothelitis
D
- History/exposure
- Culture
- Immunostaining
- Weil-Felix test w/ Proteus vulgaris antigens
T
- Doxycycline (early stages)
P
- Public awareness
18 Borrelia burgdorferi:
Biological Characteristics
Reservoirs
Transmission
Most Common Disease
Virulence Factors
Pathogenesis
Symptoms
Diagnosis
Treatment
Prevention
BC
- Spirochetes, endoflagella (“corckscrew”), thin, darkfield microscopy
- Gram(-) structure
R
- Rodents
- In Southern New England, Mid Atlantic states, & coastal/wooded California & Oregon
T
- Tick vector (Ixodes: larva, nymph, adult)
MCD
- Lyme disease
VF
- Osps (surface lipoproteins, differentially expressed, important for attachment/adhesins)
- Plasmids for Osp expression
P
- Injected during tick bite (needs >48 hours to transfer spirochetes)
- Local replication, widespread dissemination
- Local inflammatory reaction
- Early: bull’s eye expanding rash, malaise, fatigue, headache, fever, chills, myalgia
- Early-Disseminated: cranial neuropathy, meningitis, radiculoneuropathy, iritis, encrotizing retinis, cardiac dysfunction
- Late: oligoarthritis, dermatologic syndromes, neurologic demylination
D
- History
- Culture
- Serologic tests
- 2-tiered approach: immunoassay or immunoluorescent assay + Western immunoblot (confirm positive testing)
T
- Early: doxycycline, amoxicillin
- Late: IV ceftriaxone
P
- Environmental modifications
- Personal protection
- Tick checks
19 Clues to when an infection/outbreak may be due to intentional exposure
large epidemic with severe illness and high death rate among
people who are otherwise fairly healthy
likely presenting symptoms would be respiratory
if an organism was identified that wasn’t normally present in that part of the country or the world
simultaneous outbreaks around the country or organisms with an unusual pattern of antibiotic resistance
19 Biological threat from category A agents
Easily obtained & spread
High mortality
Public panic
Likely to cause fatal disease
19 Anthrax:
Microbiology
Vector
Transmission
Clinical Features
Virulence Factors
Treatment
Contagious?
Other
M
- Bacillus anthracis
- Gram positive, spore-forming bacilli
- Non-hemolytic, medusa’s head/come’ts tail
V
- Livestock
T
- Exposure to infected animals/products
- Injection drug users
- Handling rums made of animal skins
- No person-to-person
CF
- Cutaneous (95%): exposure of abraded skin to spores, purpitic painless papule, black eschar, enlarged lymph nodes
- Inhalational (5%): flu-like, mediastinal widening, hemorrhagic mediastinitis, hemorrhagic meningitis
- GI (sporadic): uncooked meat, GI symptoms
VF
- Capsule (antiphagocytic, polyglutamic acid)
- Exotoxins
- Edema toxin (affects cell function)
- Lethal toxin (affects signal transduction)
T
- Cutaneous: doxycycline or ciprofloxacin
- Inhalational/GI: Ciprofloxacin, linezolid, Meropenem (meningitis), Clindamycin (no meningitis)
- Post-exposure prophylaxis: vaccine, doxycycline, levofloxacin, ciprofloxacin
- Raxibacumab
- Pleural effusion drainage
- Vaccine
C
- No
O
- Amerithrax 2001 attacks
19 Tularemia:
Microbiology
Vector
Transmission
Clinical Features
Virulence Factors
Treatment
Contagious?
Other
M
- Francisella tularensis
- Gram negative cocco-bacillus
- Facultative intracellular pathogen
- Doesn’t take many organisms to cause disease
V
- Rabbits, Ticks, Flies
T
- Tick bite
- Contaminated animal products or water
- No person-to-person transmission
CF
- Ulceroglandular, Pharyngeal, Pneumonic, Oculoglandular, Typhoidal, Glandular
VF
- Capsule
- FPI
T
- Streptomycin
- Also gentamicin & doxycycline
- No vaccine
C
- No
O
- Martha’s Vineyard
19 Plague:
Microbiology
Vector
Clinical Features
Virulence Factors
Treatment
Contagious?
Other
M
- Yersinia pestis
- Gram negative bacillus
- Bipolar staining, “safety pin”
V
- Rodents, Fleas
CF
- Bubonic: most common, fevers, chills, weakness, headache, painful swollen lymph nodes
- Pneumonic: infection of lungs, fever, cough, difficulty breathing, bloody sputum
- Septicemic: generalized (bloodstream)
VF
- LPS,
- Type III secretion system
- Plasminogen activator
T
- Streptomycin
- Also gentamicin, doxycycline, ciprofloxacin (also for PEP)
C
Yes
O
SW US
19 Smallpox:
Microbiology
Vector
Transmission
Clinical Features
Treatment
Contagious?
M
- Variola major/minor
- Orthopox virus
V
- Human as only host
- Eradicated
T
- Most contagious from onset of rash until scabs have healed
- Droplet nuclei, direct contact, fomites
CF
- Centrifungal rash
- Lesions of same age
- Contagious after rash appears
T
- Cidofovir
- Isolation in a negative pressure room
- Vaccine: Dryvax (calf skin, before 2001) & ACAM (in vero, current)
- Contraindications: immunodeficiency, skin condition, pregnancy
- Adverse reactions: eczema, vaccinia, encephalitis
C
Yes
19 VHFs:
Microbiology
Vector
Transmission
Clinical Features
Treatment
Vaccine
Contagious?
Other
M
- RNA viruses
V
- Rodents for arena viruses
T
- Animals: aerosol, urine, feces, fomites (objects), saliva and ocular exposure
- Humans: contact with blood and body fluids
CF
- Fever, severe illness, petechiae, unexplained bleeding
- Shock
T
- Ribavirin for arenaviruses
C
- Yes
O
- Africa
20 Clinical Microbiology Laboratory:
Priorities (2)
Challenges (3)
- Accurate diagnosis
- Speed
- Managing large numbers of samples per day
- Managing individual samples
- Maintaining accuracy w/ quality control
20 Staining:
Examples
Advantages
Disadvantages
Gram stain, acid-fast stain, India ink preparation
Rapid, inexpensive
Lower sensitivity, not specific
20 Culture (bacteria):
Examples
Advantages
Disadvantages
MacConkey agar, eosin methylene blue (EMB)
high sensitivity, more information
overnight, not species-specific
20 Culture (virus):
Examples
Advantages
Disadvantages
cytopathic effect, immunofluorescent staining
specific identification
Slow, expensive, difficult to grow
20 Biochemicals:
Examples
Advantages
Disadvantages
tests on colonies (catalase, oxidase, PYR test), culture tests (tubes, API strips, Vitek cards)
species-specific
ambiguous for atypical behavior, expense
20 Antigen Testing:
Examples
Advantages
Disadvantages
PBP2a agglutination (MRSA); influenza and RSV rapid antigen tests
fast
low sensitivity
20 Nucleic acid amplification testing (NAAT):
Examples
- Rapid TB diagnostic
- Multiplex PCR
- 16S rRNA sequencing
Advantages
Disadvantages
- Rapid TB diagnostic (developing world, high sensitivity)
- Multiplex PCR (in parallel, rapid, qualitative)
- 16S rRNA sequencing (primers for conserved sequences, detecs unknown pathogens)
rapid, specific, quantitative
cost, labor, technically challenging, contamination, slow if sample sent to reference lab
20 Mass Spectrometry:
Components
Examples
- PLEX-ID
- Vitek MS
Advantages
Disadvantages
i. vaporization (ion source)
ii. measure mass-to-charge ratio (mass analyzer)
iii. abundance of molecule (mass detector)
- PLEX-ID: measures PCR, distinguishes by nucleotides
- Vitek MS: measures proteins, distinguishes peaks
rapid, general, direct from patient sample
overnight, sample prep, expense, sensitivity
