Ch. 8 ID Flashcards
List characteristics of Clostridium botulinum bacteria
Gram +
Anaerobic rod
spore-forming
prevalent in soil an marine sediment
heat and acid resistent
What is the mechanism of action of botulinum toxin?
blockage of presynaptic release of acetylcholine at the neuromuscular junction –>
flaccid descending paralysis
mydriasis, ptosis, respiratory paralysis
what is the primary cause of death in botulism?
respiratory paralysis
What is the treatment of botulism?
Botulinum Antitoxin
Adults –» trivalent antibodies to toxin (derived from horse serum)
Infants –» human-derived botulinum Ig IV (BIG-IV)
What toxin causes tetanus?
exotoxin tetanospasmin
List characteristics of Clostridium tetani bacteria
gram + Rod
anaerobe
spore-forming –> “drumstick appearance”
found in soil and animal feces
What is the mechanism of action of exotoxin tetanospasmin?
Blocks release of inhibitory neurotransmitters (glycine and GABA) at motor endplates of skeletal muscle, spinal cord, brain and sympathetic nervous system –> spastic paralysis and tetany
What type of poisoning can have a similar presentation to tetanus?
Strychnine poisoning
(found in pesticides, homeopathic meds, street drugs)
- waxing and waning intense muscle contractions, back arching, grimacing
Tx with benzos
How is tetanus diagnosed?
Clinical diagnosis
SPATULA TEST - a tongue depressor is used to touch the posterior oropharynx, will cause a patient with tetanus to uncontrollably bite down on the depressor
(reported sensitivity and specificity of > 90% for tetanus infection.)
What is the treatment for tetanus?
- aggressive supportive care
- Human Tetanus Ig (TIG) 3000-5000 units IM
- Tetanus immunization (opposite side)
- +/- Abx (Metronidazole) (questionable utility)
- other meds:
- Benzos to relax muscles
- Magnesium and labetalol for sympathetic hyperactivity
penicillin and isolated beta blockade are contraindicated
If you have a wound that requires debridement should you do it before or after administration of tetanus immune globulin?
After. Debridement can release additional toxins
How is gonorrhea diagnosed?
Nucleic acid amplification test (NAAT) of urethral/first-catch
urine, cervical, pharyngeal, or rectal specimen; sensitivity approximately
95%
What is the treatment for disseminated gonorrhea?
Ceftriaxone 1 g IV daily
What organism causes syphilis?
Treponema pallidum
Describe the characteristics of the organism treponema pallidum?
Gram negative
obligate intracellular
spirochete (corkscrew shaped)
visible with darkfield microscopy
What is the incubation period of syphilis?
2-4 weeks
Describe primary syphilis
painless genital ulcer with indurated border (chancre) that heals spontaneously over 2-6 weeks
What do you call a wartlike genital lesion?
condyloma lata (secondary syphilis)
What are the 4 components of tertiary syphilis?
- tabes dorsalis - myelopathy involving dorsal columns of spinal cord
- dementia
- gummatous lesions of mucous membranes
- Thoracic aortic aneurysms
What stage of syphilis does neurosyphilis occur?
can occur in ANY stage!
How is syphilis diagnosed?
screening test = serum rapid plasma reagin (RPR) or VDRL
confirmatory test = serum florescent treponemal antibody absorption test (FTA-ABS)
What is the treatment of primary or secondary syphilis?
Benzathine penicillin 2.4 million U IM (alternative = doxycycline × 14 days)
What is the treatment of latent or tertiary syphilis?
Benzathine penicillin 2.4 million U IM weekly × 3 (alternative = doxycycline PO × 28 days)
What is the treatment of neurosyphilis?
Aqueous penicillin G 3-4 million units IV q4h × 10-14 days
or
benzathine penicillin 2.4 million units IM qd plus probenecid PO qid × 10-14 days
Describe a Jarisch-Herxheimer reaction and when does it typically occur?
Acute fevers, headaches, myalgias, sweating within 24 hours of initial treatment of spirochete infections;
What is the treatment of Jarisch-Herxheimer reaction?
self-limited
supportive treatment
Describe the microbiology of the influenza virus.
single-stranded RNA
Orthomyxoviridae virus
How is EBV typically transmitted?
bodily secretions
What lab finding is common in those with mono?
transaminitis
How is Mono diagnosed?
Heterophil antibody tests, eg, Monospot (viral capsid immunoglobulin M [IgM])
What organism causes rabies?
Lyssavirus (specifically genotype 1)
What are the symptoms of encephilitic form of rabies?
- periodic episodes of hyperactivity
- hypersalivation
- periodic spasms, including inspiratory (aerophobia) and (pharyngeal) hydrophobia
What organism causes sporotrichosis?
fungus – Sporothrix schenckii
How is sporotrichosis diagnosed?
biopsy/fungal cultures
however, treat based on clinical suspicion
What is the treatment for sporotrichosis?
Intraconazole for 3-6 MONTH
What should you consider in travelers, immigrants or patients with unexplained fever, abdominal pain, diarrhea, or eosinophilia?
parasitic helminths
What is the most common helminth infection in the US?
Pinworm (Enterobius vermicularis)
which is a type of nematode aka roundworm
How is pinworms diagnosed?
via scotch-tape swab of anal verge and direct visualization of worms
How is Pinworms/Enterobius vermicularis treated?
Albendazole or mebendazole
Which parasite hatches eggs in the small intestine, mature in the lungs and ascend the bronchial tree to be swallowed?
Common Roundworm
(Ascaris Lumbricoides)
Hookworm and strongyloides also ascends bronchial tree but eggs hatch into larvae in soil and travels via blood to lungs (rather than eggs hatching in intestine)
What do you call the dry cough, chest pain, and low grade fever due to eosinophilic pneumonitis during migration through lungs associated with ascaris lumbricoides?
Loeffler Syndrome
How is Common Roundworm (Ascaris Lumbricoides) diagnosed?
stool microscopy (Ova and parasites)
How is Common Roundworm (Ascaris Lumbricoides) treated?
albendazole or mebendazole
How does Hookworm cause anemia?
- chronic blood loss from attaching to intestinal mucosa
- iron deficiency anemia and nutritional deficiencies
Which parasite is known to occasionally cause rectal prolapse?
whipworm (trichuris triciura)
How is Strongyloides (Strongyloides stercoralis) treated?
Ivermectin or albendazole
Which parasite commonly causes muscle pain and tenderness, fever, and periorbital swelling?
Trichinella (Trichinella spiralis)
Which nematode uses mosquitos as its vector?
Lymphatic Filariasis/Elephantiasis (Wuchereria bancrofti and Brugia malayi )
How is Lymphatic Filariasis/Elephantiasis (Wuchereria bancrofti and Brugia malayi) treated?
diethylcarbamazine (DEC) or ivermectin
What vector does Onchocerciasis/River Blindness (Onchocerca volvulus) use?
Blackfly (simulium) - found near fast-flowing rivers and streams
How do you treat Onchocerciasis/River Blindness (Onchocerca volvulus)?
Ivermectin
What vector does Loa loa use?
deerfly
How does loa loa present and how do you treat Loa Loa?
worm can be visible on conjunctival exam of eye
tx: DEC
Which tapeworm can cause a megaloblastic anemia due to B12 deficiency?
Diphyllobothrium latum
How is Diphyllobothrium latum ingested?
undercooked fish
How is Echinococcus species ingested?
Feces of sheepdogs, cattle,
wolves, foxes
Which parasite causes larval cysticerci in brain, striated muscle, and liver (aka cysticercosis)?
T. solium
How is T. Solium treated?
Praziquantel
How long does HIV seroconversion take?
3-12 weeks after exposure
What is the treatment for AIDS patient with Histoplasmosis?
Severe –> IV amphotericin
mild –> itraconazole
What is the treatment of coccidiomycosis in AIDS patient?
Same as Histoplasmosis
Severe –> IV amphotericin
mild –> itraconazole
What organism causes PCP (pneumocystis) pneumonia?
P. jirovecii – a yeast-like FUNGUS
What lab finding is common in PCP pneumonia?
elevated LDH
(also elevated A-a gradient)
What is the treatment for PCP pneumonia?
TMP-SMX
(in sulfa allergy, treat with clindamycin + primaquine)
■ Prednisone if A-a gradient > 35 or Pao2 < 70 mm Hg
■ Prophylaxis with TMP-SMX, 1 DS tab daily is indicated for CD4 < 200 cells/
mm3 and greatly decreases the incidence of PCP.
Cryptococcal meningitis is most commonly in patients with CD4 <_____ cells/mm3
100
How is cryptococcal meningitis diagnosed?
LP – fungal cultures is definitive
CSF cryptococcal antigen – is highly sensitive and specific
(India ink stain of CSF is only positive 75% of time)
What is the treatment for cryptococcal meningitis?
Admit for IV amphotericin and PO flucytosine, then requires lifelong tx with fluconazole
Describe microbiology of toxoplasma gondii
Protozoan parasite
Obligates intracellular
Found worldwide
Felines are host
What is the treatment for toxoplasmosis?
Pyrimethamine + sulfadiazine (+ folinic acid)
■ Steroids are indicated for significant edema/mass effect.
Primary CNS lymphoma occurs most commonly with CD4 < ___ cells/mm3
50
What is the CT appearance of Primary CNS lymphoma?
Focal lesion (usually solitary) that enhances with contrast. Hyperdense/ isodense periventricular enhancement is often seen.
What is the treatment for Primary CNS lymphoma?
Chemotherapy + radiation
(median survival <1 month)
How does Progressive Multifocal Leukoencephalopathy (PML) appear on CT?
Single or multiple NON-enhancing white-matter lesions
What is the treatment for PML?
Highly active antiretroviral therapy (HAART)
prognosis is poor
What is the treatment of thrush?
mild –> nystatin or clotrimazole topical therapy
recurrent/refractory or severe disease –> fluconazole
What are the three most common causes of esophagitis in HIV-positive patients?
candida albicans (especially if with thrush)
HSV
CMV
What is the treatment for esophagitis in HIV patient?
Presence of thrush: Empiric trial of fluconazole
Absence of thrush or no response to fluconazole: Endoscopy and biopsy to guide treatment
What is the treatment for Mycobacterium avium-intracellulare (MAI) infection?
Clarithromycin or Azithromycin +Ethambutol
What do you call the angioproliferative disease occurring in HIV patients with prior HHV-8 infection?
Kaposi sarcoma
What are the signs and symptoms of Kaposis Sarcoma?
■ Papules or nodules that are pink, red, or purple in color
■ Painless/nonblanching
■ Commonly on lower limbs, face, mouth, and genitals
■ Respiratory and GI involvement can occur
What is the treatment for Kaposi Sarcoma?
antiretroviral therapy – disease may regress as CD4 counts rise
Palliation:cryotherapy, radiotherapy, systemic chemo
What is the #1 cause of AIDS -associated blindness?
CMV retinitis (occurs with CD4 <100)
causes a severe necrotic vasculitis and retinitis
Describe the eye / retinal exam of CMV retinitis
Retina: Fluffy white perivascular lesions (“cotton-wool spots”)
What is the treatment for CMV retinitis?
Ganciclovir
What is a common complication of treatment with NRTIs? (eg, stavudine, zidovudine, didanosine, and lamivudine)
Lactic acidosis – untreated mortality rate of 50%
How is Hantavirus spread?
inhalation of feces/urine or direct bite from rodents (primarily deer mouse)
majority occur in southwestern united states
What is Hantavirus Pulmonary Syndrome?
characterized by a flulike prodrome for
3-4 days, followed by noncardiogenic pulmonary edema and hypotension
What is Hantavirus hemorrhagic fever?
fever,
hemorrhage, hypotension, and renal failure
What are common lab findings in Hantavirus infections?
Thrombocytopenia and marked leukocytosis
How is Hantavirus definitively diagnosed?
Immunofluorescent or immunoblot assays
What is the treatment for Hantavirus infections?
Supportive care
What type of virus is west nile virus?
Flavivirus
What are the symptoms of West Nile fever?
fever, flu-like illness with URI
and maculopapular central rash
symptoms last about 3-6 days
What are CSF findings of meningoencephalitis?
increased lymphocytes and protein,
normal glucose
How is meningoencephalitis diagnosed?
IgM antibody in CSF or serum.
What is the treatment for west nile virus?
supportive
What organism causes Lyme disease?
Borrelia burgdorferi
What is the microbiology of Borrelia burgdorferi?
Gram-negative bacterium
Spirochete (helical shape)
Extracellular
Tick transmitted
What are the three stages of lyme disease?
Early localized
early disseminated
late disseminated
How is Lyme Disease diagnosed?
Screening test: ELISA (89% sensitive, 72% specific, false positives common)
Confirmatory test: Western blot assay
What is the treatment for Lyme Disease?
Depends on the stage
1. early localized –> doxycycline PO x 21d
2. Early disseminated with arthritis –> Doxycycline PO x30d
- Early disseminated with neuro or cardiac sx
- if isolated CN palsy or first degree AV block –> Doxycycline PO × 21 d
OR
–> Ceftriaxone IV at meningitic doses (all other presentations)
When is Lyme Disease prophylaxis indicated? Dose?
Ixodes tick bite and only if tick is attached > 36 hours
Single 200-mg dose doxycycline within 72 hours of tick removal
Which ticks are responsible for the spread of Rickettsia ricketsii (RMSF)?
Dermacentor variabilis (dog tick) and Dermacentor andersoni (wood tick)
Describe the pathogenesis of RMSF?
Tick bite and transmission → invasion and proliferation of organism within
capillary and precapillary endothelial cells → perivascular inflammation →
platelet and fibrin occlusion of vessels and multisystem disease
Describe the rash of Rocky Mountain Spotted Fever.
Maculopapular → petechial/purpuric
■ Starts on wrists/ankles
■ Spreads centripetally (extremities → trunk)
■ Classically involves palms and soles (50%)
How is Rocky Mountain Spotted Fever diagnosed?
based on clinical suspicion
Serology can be done but takes 6-10 days
Which lab findings are common in RMSF?
Hyponatremia and thrombocytopenia (in advanced disease)
What is the treatment for RMSF?
■ Treat empirically for clinical suspicion due to high mortality rates (roughly
3%-5% despite treatment, 25% if untreated).
■ Supportive therapy, low threshold for admission
■ Antibiotics: Doxycycline, tetracycline, or chloramphenicol
What are common complications of RMSF?
ARDS
myocarditis, CHF
DIC
seizures, encephalitis
What are the two types of ehrlichiosis?
human monocyte ehrlichiosis
human granulocytic ehrlichiosis
(depends on which immune cell is invaded)
What organism causes human monocyte ehrlichiosis?
Ehrlichia chaffeensis
What organism causes human granulocytic ehrlichiosis?
Anaplasma
phagocytophilum.
Describe the microbiology of Ehrlichia chaffeensis and Anaplasma phagocytophilum.
Gram-negative coccobacilli
Obligates intracellular (monocyte or
granulocyte)
Tick transmitted
What lab findings are commonly seen in Erhlichiosis?
Leukopenia, thrombocytopenia, transaminitis (50%-90%)
How is Erlichiosis diagnosed?
IgG antibody titers or culture/biopsy
■ Definitive: PCR
What is the treatment for Erlichiosis?
Doxycycline, tetracycline, or rifampin
What organism causes Babesiosis?
Babesia genus;
Parasitic protozoan
Pleomorphic
Intraerythrocytic
Transmitted by ticks
what is the vector for babesiosis? reservoir?
Ixodes ticks with a reservoir in deer and mice
How does babesiosis present?
Mild –> flu-like illness +/- splenomegaly
Severe –> hemolytic anemia, jaundice, renal insufficiency, ARDS
How is Babesiosis diagnosed?
Thick and thin Giemsa-stained smears
■ Erythrocytes show budding tetrad in “Maltese cross” formation.
What is the treatment for Babesiosis?
■ Mild disease → no treatment
■ Severe disease or postsplenectomy → quinine + clindamycin
■ Exchange transfusion if fulminant
What pathogen causes Q fever?
Coxiella burnetii
Describe the microbiology of Coxiella burnetii
Gram-negative bacterium
Obligates intracellular
Transmitted by ticks, exposure to animal
products or raw milk
Highly infectious
What are the symptoms of Q Fever?
flulike symptoms, pneumonia, hepatitis
How is Q fever diagnosed?
■ Often clinical
■ Definitive: PCR, serologies (positive 2-3 weeks after infection)
How is Q fever treated?
Doxycycline, tetracycline, or chloramphenicol
What are 3 common complications of Babesiosis?
Endocarditis (up to 68%), granulomatous hepatitis, osteomyelitis (peds)
What pathogen causes Colorado tick fever?
Colorado tick fever virus
How is Colorado tick fever virus transmitted?
D. andersoni
(wood tick)
What are the symptoms of Colorado Tick Fever?
Classic biphasic fever and flulike symptoms, each lasting for a few days
rarely can cause meningoencephalitis
How is Colorado Tick Fever diagnosed?
clinically
What is the treatment for Colorado Tick Fever?
supportive
Malaria is spread by the ____ mosquito.
Anopheles
Describe the lifecycle of plasmodium species
Mosquito transmits asexual haploid form of Plasmodium → migrates to liver
and matures to produce merozoites → released from liver and invade RBCs →
mature in 48-72 hours causing RBC lysis and release of additional merozoites
→ invade more RBCs → hemolytic anemia
What are the symptoms of uncomplicated malaria?
flulike illness, mild jaundice, and splenomegaly (after several days of illness)
What is the presentation of severe or complicated malaria?
toxic/septic appearance
acute lung injury
What is the treatment for uncomplicated malaria in adults (Central American and Caribbean)?
Chloroquine phosphate
What is the treatment for uncomplicated malaria in PEDIATRICS (Central American and Caribbean)?
Chloroquine Phosphate
What is the treatment for uncomplicated malaria in adults (South American, South Asia, Africa – chloroquine resistant)?
Quinine Sulfate (PO) + Doxycycline
OR
Atovaquone/proguanil
OR
Mefloquine
What is the treatment for uncomplicated malaria in PEDIATRICS (South American, South Asia, Africa – chloroquine resistant)?
Quinine Sulfate (PO) + PYRAMETHAMINE SULFADOXINE
OR
Atovaquone/proguanil
OR
Mefloquine
What is the treatment for complicated malaria in adults?
Quinidine Gluconate (IV) +Doxycycline
What is the treatment for complicated malaria in pediatrics?
Quinidine Gluconate (IV)
What species typically causes complicated/severe malaria?
Plasmodium falciparum
How is malaria definitively diagnosed?
Plasmodial parasites on Giemsa-stained thick and thin smears
For P. vivax, P. ovale, which have a dormant hepatic phase, add ______ to prevent relapse, but FIRST test for _______.
primaquine
G6PD
What are the signs and symptoms of Ebola?
fever, headache, myalgias
n/v/d
rash
unexplained easy bruising/bleeding
causes a viral hemorrhagic fever
What is the treatment for ebola virus?
isolation precautions
supportive care
How is ebola spread?
bodily fluids
_____ presents with fever and dramatic bone pain in the traveler
Dengue
What virus causes Dengue?
Flavivirus
Flavivirus is transmitted to humans by the ______ mosquito.
Aedes – bites during the day (in contrast to Anopheles which causes malaria, bites at night or dusk)
What is the incubation period for malaria?
1-4 weeks
What is the incubation period for Dengue?
5-10 days
What are the signs & symptoms of Dengue?
high fever, n/v, severe bone pain/myalgias/arthralgias
“Dengue facies” = classic facial edema
Pale morbilliform rash develops following defervescence; starts on trunk,
spreads to extremities/face
How is Dengue diagnosed?
clinically, but rule out malaria
Definitive Dx by ELISA
What is the treatment for Dengue?
supportive
What is a risk factor for Dengue hemorrhagic fever?
most often occurs following exposure to second serotype
Describe the course of Dengue Hemorrhagic fever.
Initial clinical course is similar to classic dengue.
Second phase of illness begins as initial symptoms are resolving
Fatigue
shock
bleeding diathesis with hemorrhagic pleural effusions
thrombocytopenia
mortality = 50% without care (<5% with care)
What pathogen causes Leptospirosis?
bacterial spirochete Leptospira interrogans
How is leptospirosis transmitted?
percutaneous or mucus membrane contact with
FRESHwater contaminated by the urine of infected rodents, livestock, or domestic animals
Describe the signs and symptoms of the Acute bacteremic phase of leptospirosis?
range from mild illness to abrupt high fever/chills, intense headache (often worst of life) and severe myalgias
Conjunctive suffusion (redness without exudates) = pathognomonic
What are the signs and symptoms of Weil syndrome caused by Leptospira?
severe icterus
renal failure
hemorrhage
acute lung injury/ARDS
What lab abnormalities are seen with Leptospirosis?
increased WBC and bilirubin (relative mild increase in alk phos and transaminases)
How is leptospirosis diagnosed?
acute phase –> clinical dx
definitive: isolation of leptospires in urine or CSF
How is Leptospirosis treated?
mild disease: Doxycycline/Amoxicillin
severe disease: penicillin/ampicillin/ceftriaxone
(treatment is most effective without first 4 days and may prevent Weil syndrome)
treat empirically if suspicion is high
What pathogen causes Chagas disease?
Trypanosoma cruzi
How is trypanosoma cruzi transmitted?
by contact with feces of the blood-sucking triatomine type of reduviid bugs (“kissing” bugs)
What are the signs and symptoms and timing of the acute phase of Chagas disease?
2-30 days after infection
weeks-months duration
edema at the inoculation site (often the eyelid)
malaise, fever, anorexia, myalgias
hepatosplenomegaly, lymphadenopathy
What are the signs and symptoms and timing of the chronic phase of Chagas disease?
10-20 years postinfection
Cardiomyopathy
Megaesophagus
Megacolon
How is Chagas disease diagnosed?
acute phase –> observe parasite on thick and thin blood smears
chronic disease –> serologic testing
What is the treatment for Chagas disease?
Nifurtimox
What medications are used for HIV post-exposure prophylaxis?
Tenofovir-emtricitabine (Truvada) + raltegravir (Isentress)
Recommended in known HIV+ or at high risk of HIV
What medications are used for Hep B post-exposure prophylaxis?
Hepatitis B immunoglobulin (HBIG)
Hepatitis B vaccination: Usually given as three doses over 4-6 months with first dose given with HBIG in different site
recommended for any blood or bodily fluid exposure if not fully vaccinated or known nonresponder
What is the only vaccine given at birth?
Hep B
Which 6 vaccines are given at 2 months old?
Hep B - second dose
RV (rotavirus)
DTaP (diptheria, tetanus, and pertussis)
Hib (h. influenzae type b)
PCV (pneumococcus)
IPV (polio)
What is the youngest age you can begin getting an annual influenza vaccine?
6 months
When are MMR and Varicella vaccines administered
12 months
In Lyme meningitis, what CSF finding is most sensitive?
Borrelia Burgdorferi Antibody
(PCR is positive in less than half of patients)