Micro Flashcards
hepatitis
*in general, hep viruses are covered - capsid/envelope
A: PicoRNAvirus, capsid
- shellfish
- can be asymptomatic or cause acute viral hep, one month duration and self-limiting - hepatocyte swelling, monocyte infiltration, Councilman bodies
- jaundice in ADULTS
- vaccine!
E: again capsid, ssRNA
10X more deadly than HAV, 1/5 pregnant women die
- patchy necrosis
B: sex, blood, TORCH (blood mixing, doesnt cross placenta)
- DNA virus, enveloped, DNA polymerase
- partially circular dsDNA –> RNA intermediate –> dsDNA (brings RT)
- HBsAg, HbEAg (not a part of mature HBV virion), HbCAb (window period), HbEAb, HbSAb
- acute infection is self-limiting, initially it presents like serum-sickness (fever, rash, arthralgias)
- ground glass appearance
- nephritis, polyarteritis nodosa, aplastic anemia
- chronic infection in NEWBORNS - give at risk neonates HepB Igs
- vaccine
- give other at risk - lamividine, NRTIs, INFa
C: childbirth, needles
- FLAVIvirus, envelope, pos ssRNA
- high antigenic variation - RNA pol lacks 3-5’ exonuclease/proofreading activity
- lymphoid aggregates with focal areas of macrovesicular steatosis
- chronic infection - lymphocytes in portal tract –> cirrhosis or HCC
- cryoglobulins, lichen planus, increased risk of DM, AI thyroiditis, etc. (point is many more than for HBV)
- treatment is ribavirin and INFa, protease inhibitors
D: negative RNA virus, enveloped, requires HbSAg to infect
- also confers HCC risk
*hepatitis can give false positives on VRDL test
coxsackie virus
PicoRNAviridae - naked, pos RNA
A- hand, foot, and mouth disease
B- dilated cardiomyopathy
-devil’s grip - sharp CP, difficulty breathing
treatment is supportive
aseptic meningitis
enteroviruses - fecal-oral transmission are the most common cause of aseptic meningitis
amphotericin
amphotericin and nystatin bind to ergosterol –> pores in cell membrane
-resistance by changing the amount of ergosterol in the fungal membrane
ADRs- because it can bind to human membranes (use liposomal formulation)
- infusion-related IMMEDIATE reaction - fevers, chills, muscle spasms, hypotension, headache AND thrombophlebitis at injection site
chronic use reaction - renal damage –> pre-renal azotemia (so volume expand before administration), renal tubular acidosis, Mg2+ wasting, hypokalemia, anemia
- dont give AGs, cyclosporine at the same time
- permanent loss of renal function prop to cumulative total dose
intrathecal admin (into SC or subarachnoid space) - seizures, etc.
flucytosine
Fl-cytosine - halts DNA and RNA replication
flucytosine + ampho to treat cryptococcal meningitis
nystatin
like amphotericin
use against Candida
azoles
inhibits ergosterol SYNTHESIS - halts fungal CYP 450
voriconazole - CYP450 inhibitor, reduce other meds (cyclosporine, tacrolimus, statins)
- transient visual changes
fluconazole - candida, prophylaxis for cryptococcal meningitis - has high CNS penetration
itraconazole for dimorphic fungi
ketoconazole - topical, not used systemically because it is a strong CYP inhibitor
…terbinafine is similar
griseofulvin
binds to fungal cell microtubules
CYP inducer, granulocytopenia
oral formulation accumulates in keratin tissues
terabinafine
interferes with ergosterol synthesis - inhibits squalene epoxidase –> squalene accumulates and is toxic to fungal cells
use against dermatophytes
oral griseofulvin and oral terbinafine - tinea capitis
echinocandins
-fungin
block synthesis of glucan, part of fungal cell wall
well tolerated
use against Candida - IV
antifungals against Candida
nystatin - for oral/esophageal candidiasis
fluconazole
echinocandins - first line according to class
opportunistic infections
Candida
- dimorphic - but opp, yeast at 20degC, pseudohyphae at 30degC, catalase positive
- cutaneous - diaper rash
- oral candidiasis in immunocompromised/pts on oral steroids - rinse following oral steroid use
- vulvovaginal candidiasis - NO change in vaginal pH
- endocarditis - Candida grows in heroin
- Candida also associated with indwelling catheters
- disseminated candidiasis in neutropenic pts
- treatment options - fluconazole, nystatin (oral/esophageal disease), caspofungin, ampho B
Aspergillus
Cryptococcus neoformans
Mucormycosis - fungi proliferate in blood vessels
- bread mold
- non-septate, branch 90deg angles
- surgical debridement of necrotic tissues, ampho B
Pnuemocystis jirovecii
Sporothrix schenckii - dimorphic, cigar shaped budding yeast, grows in ROSEttes
- local pustule –> nodules along lymphatics
- treat with itraconazole or KI
Aspergillus fumigatus
ACUTE angles, septations
catalase positive
1) allergic bronchopulmonary aspergillosis - associated with asthmatics and CF patients
2) aspergillomas - hypoattenuation (halo sign)
3) angioinvasive aspergillosis - affects immunocompromised and pts with CGD
- invades blood vessels –> disseminates throughout body –> fever, cough, hemoptysis
- ring-enhancing lesions on CT
- red herring - mucor
medical treatment + surgical debridement
Cryptcoccus
heavily encapsulated
soil/pigeon droppings
urease positive, NOT dimorphic
ddx - bronchopulmonary washings, culture on Sabourauds agar (for fungi), stain with mucicarmine (stains fungus pink) or methanimine silver stains, latex agglutination test detects polysaccharide capsule
hematogenous spread –> meningitis - stain LP with India ink
-soap bubble lesions in gray matter
[clinically - CRAG is used (lateral flow assay, enzyme immunoassay, latex agglutination)]
treat with ampho B + flucytosine, followed by fluconazole
Pneumocystis jiroveci
bronchioalveolar lavage - methamine silver stain, disc-shaped yeast
diffuse interstitial pneumonia
bactrim for prophylaxis
- other treatment/prophylaxis options - pentamidine, dapsone (prophylaxis), atovaquone, start prophylaxis when CD4 < 200
Nematodes (round worms)
I TWOLD you about tissue nematodes
microfilariae (most), albendazole
EATT - Enterobius, Ascaris, Toxocara, Trichinella
SANd - Strong, Ancylostoma, Necator
type1 response by eos - neutralize? histamine and LTs
type 2 - eos attach to surface via IgE –> release MBP
Enterobius vermicularis (pinworm) - anal pruritis - pyrantel pam or bendazoles
Ascaris lumbricoides (roundworm)
- migrates from nose/mouth, fecal-oral - knobby oval eggs in stool
- bowel obstruction, biliary obstruction, intestinal perf
- bendazole
Strongyloides - vomiting, diarrhea, epigastric pain (red herring peptic ulcer)
- ivermectin, bendazoles
Ancylostoma duodenale, Necator (hook worms)
- cause anemia by sucking blood from intestinal wall
- cutaneous larva migrans - pruitic, serpinginous rash from walking barefoot on contaminated beach
- bendazoles, PAM
Trichinella spiralis - muscle + periorbital edema
- undercooked pok, bendazoles
Trichuris trichura - asymptomatic, rectal prolapse in kids, fecal oral
- bendazole
[Dracunculus medinesis - contaminated water that contains crustacean (which contains larvae) –> host stomach –> migrate to surface of skin –> painful ucler
- worms emerging from ulcer
- “Dracula’s bite”]
………………………………………………………………………………………
Toxocara canis
- dog/cat/wolf feces - nematodes migrate through intestinal wall into blood
- dont mature past larva state - visceral larva migrans
- affects heart, liver, eyes, CNS
- bendazole
Onchocerca volvulus
- black flies bite –>… scattered pruitic hyperpigmented papules (loss of elastic fibers)
- microfilariae can cause blindness (aka river blindness)
- treat with ivermectin
Loa Loa - deer flies
- worm migrates through subQ tissue, causes transient angioedema + subQ swellings
- can see worm crossing conjunctiva
- diethylcarbamazine
Wuchereria bancrofti - mosquito is intermediate host
- elephantitis (after 1 yr), LAD, cough
- diethycarbamazine
Cestodes
= tapeworms, a tapeworm named TED
stool O&P, praziquantel
Taenia - undercooked meat (cow, pig) or water contaminated with animal feces
- neurocysticerosis (from feces) - cystic brain lesions –> seizures, hydrocephalus, use albendazole
- swiss cheese brain
Diphyllobothrium latum
- undercooked fish –> diarrhea + B12 deficiency
Echinococcus granulosus
- dogs are definitive hosts, sheep are intermediate host
- hydatid cysts in liver - with eggshell calcifications, cyst rupture –> analyphylaxis
- albendazole
Trematodes
= flukes, SCP
praziquantel
Schistosoma
- penetrate skin of swimmers –> enter bloodstream –> travel to liver, mature into adults, adults lay eggs –> humans pee/poop eggs…
- snails ingest human feces and become intermediate host
- Mansoni (lateral spine) and Japonicum (no spine) - mesenteric veins, portal HTN (fibrosis and inflammation)
- Hematobium - terminal spine, bladder SCC, pulm HTN
- migrates against portal flow
Chinese liver fluke (C. sinesis) - undercooked fish
- biliary system –> pigmented gallstones
- associated with cholangiocarcinoma
[Paragonimus westermani - lung fluke –> chronic cough with bloody sputum
- transmitted through undercooked crab meat]
Entamoeba histolytica
cyst in GI –> trophozoites –> colon, portal circulation –> R liver lobe abscess
invasive, blood diarrhea
ulcerations in colon
trophozoites that contain endocytozed RBCs
metro
luminal agent to eliminate cysts - paramycin, iodoquinol
Plasmodium
blood borne protozoa, splenomeg
mosquito bite –> sporozoites into human blood –> mature into trophozoites in liver –> hepatic schizonts in liver –> rupture of schizonts –> merozoites, which infect RBCs
ring form of immature schizont shape - other diagrams say early trophozoite is the ring form
merozoite can from gametocytes in RBC
Giema stain - parasites will be in RBCs
malariae - fever/72 hrs
vivax, ovale - fever/48hrs, dormant hypnozoites
- can see red stippled RBC
falciparum - most severe malarial illness, neuro symptoms (due to parasitized RBCs occluding capillaries, can also occlude in kidneys and lungs)
-banana-shaped
chloroquine (blocks plasmodium heme polymerase, but most regions have acquired resistance), alternative is mefloquine (or atovaquone, proguanil)
primaquine to target dormant hypnozoites - be careful in pts with G6PD
falciparum, if life-threatening - artemisins or IV artesunate
quinidine for resistant species
Parvovirus
non-enveloped, ssDNA virus (only ssDNA virus)
- aplastic crisis in sickle cell pts - erythroid precursor cell has been destroyed
- RBC destruction in fetus –> hydrops fetalis
this is NOT aplastic anemia - which is a pancytopenia
herpes viruses
herpes viruses = linear dsDNA, enveloped
- ddx by PCR (can do viral culture for skin/genitalia)
HSV1 - …keratoconjunctivitis, temporal lobe encephalitis, esophagitis, erythema multiforme
HSV2 - viral meningitis
VZV
- chicken pox - starts on trunk, will go to face and extremities
- light microscopy of sample from vesicle base - intranuclear inclusions in keratinocytes and multinucleated giant cells (Tzanck smear)
- skin biopsy = acantholysis (loss of intercellular connections), intraepidermal vesicles
- postherpetic neuralgia
- visual impairment can occur - if VZV reactivates in trigeminal ganglion V1
CMV - owl eye inclusions
- binds to integrins (heparan sulfate)
- pneumonia in transplant pts, retinitis in AIDS pts (hemorrhage, cotton-wool exudates, vision loss)
- congenital CMV - hearing loss, seizures, rash, periventricular calcifications
HHV 6 = Roseola - saliva
- HIGH fever followed by diffuse rash
Treponema pallidum
spirochete, motile helical organism - dark field microscopy (why? - it is gram negative but very thin, so cant be visualized on a gram stain)
VDRL and RPR detect antibody against cardiolipin - cardiolipin is a byproduct of treponemal infection
- tests are affected by antitreponemal therapy
treponemal tests are FTA-ABS (flourescent antibody), MHA-TP (hemagglutinnation) - treponemal antigens
- these antigens will remain positive for life
due to cost - most labs have inverted the order in which they perform serological testing
v. s. H. ducreyi –> chancroid (ulcer with regional LAD)
- culture in hematin-enriched medium
Strep
optochin - viridans is resistant, pneumo sensitive
- both are a-hemolytic
- s pneumo - rusty sputum, no virulence without capsule (acquire capsule by transformation)
bacitracin - GBS resistant, S pyogenes are sensitive
pyogenes - bacitracin sensitive, hyaluronic acid capsule, PYR pos, M protein prevents phagocytosis
- cellulitis, impetigo
- scarlet fever (erythrogenic toxin, sandpaper like rash, fever), TSLS, nec fasc
- ASO titer or anti-DNase B antibodies
GBS - pneumonia, meningitis, sepsis in babies
- CAMP factor enhances the area of hemolysis
- hippurate pos, Pyr negative
- treat moms with intrapartum penicillin prophylaxis
Staph
S. aureus - b-hemolytic, protein A
- inflammatory disease - skin infections, abscesses, etc.
- TSS - toxin binds to MCH and T cell receptor, shock, desquamation, elevated liver enzymes
- scalded skin syndrome (exfoliative toxin)
- rapid-onset food poisoning (heat stable)
- MRSA - altered PBP
S. epi - …urease pos, doesnt ferment mannitol (unlike S aureus)
Leprosy
disease of skin and nerves (Schwann cells)- why?
- because leprae grows at core body temperature
transmitted in unhygienic conditions - through respiratory route, armadillo
presentation depends on strength of cell-mediated immune response
- tuberculoid leprosy - occurs in pts with Th1 mediated response –> hypopigmented skin plaques, hair follicle loss, focally decreased sensation
- lerpromatous leprosy - occurs in pts who have a weak Th1 response, and respond with Th2 instead
- macrophage killing is limited –> mycobacteria disseminate –> tuberculoid presentation + leonine facies, testicular destruction, blindness, etc.
ddx by - skin biopsy, PCR
treat with dapsone, rifampin (+ clofazamine)
E coli
g- rod, fimbriae (UTIs), K capsule (pneumonia, meningitis)
- green on EMB agar
EIEC - invasive, dysentery, similar to Shigella
ETEC - heat labile and heat stable enterotoxins = 2 toxins
- does NOT invade, travellers diarrhea
EPEC - Pediatric
- no toxin - adheres –> flattens vili
EHEC O157:H7 - only one that does NOT ferment sorbitol or have glucuronidase
- dysentery - toxin causes necrosis and inflammation
- HUS
Klebsiella
very mucoid colonies
Campy and Vibrio
CAMPY
g-, comma shaped with polar flagella (looks like a swirly macaroni), oxidase positive
- grows at 42degC - (hot Camp fire)
- fecal-oral transmission, undercooked meat, contact with infected animals - bloody diarrhea (esp in kids)
VIBRIO
comma shaped, also oxidase pos, grows in alkaline media, acid labile
- acquired through shellfish
- enterotoxin activates Gs
Salmonella and Shigella
g-, non-lactose fermenters, oxidase negative, invade GI tract via M cells (of Peyers patches), endotoxin (S typhi also has Vi capsule, Shigella has shiga toxin)
SALMONELLA general - H2S production, motile, requires high innoculum
- antibiotics prolong fecal excretion
Salmonella typhi - carried in gallbladder
- monocyte response
- constipation
- vaccine against Vi capsule
- typhoid fever - treat with ceftriaxone, FQ
Salmonella other - human and animal reservoirs (other have only human reservoirs)
- neutrophil response
- diarrhea - no antibiotics needed
Shigella - low innoculum (fingers, flies, food, feces)
- cell-to-cell spread (Salmonella moves hematogenously)
- bloody diarrhea
- neutrophil response
Yersinia
g- rod, dog feces/pork, daycares
pseudoappendicitis or acute diarrhea
H pylori
curved, flagellated, g- rod
triple - catalase positive, oxidase positive, urease positive
- colonizes antrum of stomach (base, closest to the pylorus)
risk factor for: peptic ulcer disease, gastric adenocarcinoma, MALT lymphoma
treat with amoxicillin (or metro), clarithro, and PPR
spirochetes
Leptospira interrogans - found in water contaminated with animal urine
- leptospirosis - flu-like, calf myalgias, jaundice, photophobia is conjunctiva erythema, surfer in Hawaii
- Weil disease, icterohemorrhagic leptospirosis - severe jaundice and azotemia, fever, hemorrhage, anemia
Lyme disease - ixodes tick
- natural reservoir is the mouse, common in NE US
1) erythema migrans + flu-like symptoms
2) early disseminated - bilateral Bells palsy (unilateral bells palsy is due to HSV), AV block, migratory arthritis
3) late disseminated - encephalopathy, chronic arthritis
- doxy, amoxicillin (or cef for erythema migrans?)
note- Babesia (blood protozoa) is also transmitted by this tick
- fever and hemolytic anemia
- asplenia increases risk of severe disease
- ring form and maltese cross in RBCs
- PCR to ddx
- treat with atovaquone and azithro
Syphillis
1) chancre - use dark field microscopy to visualize fluid from chancre
- side note - chancROID is painful!
2) disseminated disease - rash (on palms and soles), condylomata lata (warty, white growth on butt), patchy hair loss
- confirm ddx with FTA-ABS
3) gummas (chronic granulomas on face), aortitis, neurosyph (positive Romberg, test spinal fluid), Argyll Robertson pupil
- stroke without HTN
congenital syphilis - linear scars at angle of mouth, snuffles, saddle nose, notched teeth and mulberry molars, short maxilla, saber shins (shin that juts anteriorly), CN8 deafness
- treat mom early - transmission can occur even in first trimester
- often results in stillbirth, hydrops fetalis
why would VRDL be falsely positive - viral infection (EBV, hep), drugs, rheumatic fever, lupus, leprosy
Jarisch-Herxheimer reaction
vagina
Gardnerella - elevated pH
- gray vaginal discharge with fishy odor, nonpainful (vaginitis would be painful) - Whiff test (KOH enhances odor)
- clue cells
- metro of clinda
Trichomonas - only exists in humans, elevated pH
- green discharge - itching and burning, strawberry cervix
- metro for pt AND partner
Candida
- normal pH, treat with an azole
Rickettsial diseases
doxy
Rocky Mountain spotted fever - South atlantic states, dermacentor tick
- triad: headache, fever, rash (vasculitis)
(rash on palms and soles - RMSF, Coxsackie, Syphilis)
Typhus - fleas (endemic), epidemic (louse)
- rash starts centrally and spreads out, spares palms and soles
Ehrlichiosis - tick
- monocytes with mulberry-like inclusions in cytoplasm
Analplasmosis - tick
- granulocytes with morulae in cytoplasm
Q fever - Coxiella, spores are inhaled from cattle, sheep
- pneumonia, common cause of culture negative endocarditis
Chlamydiae and gonorrhea
Chlamydia - most common bacterial STI in US
- cant make its own ATP
- elementary (dense) body is enfectious –> reticulate body replicates by fission
- C. Trachomatis - reactive arthritis, follicular conjuntivitis, urethritis, PID
- C. pneumo, C. psittaci (parrots) - atypical pneumonia, transmitted by aerosol
- ddx with PCR, NA amplification test
- treat with azithro or doxy (+ cef, targets the gonorrhea) - note chlamydia has no cell wall
C trach serotypes
- ABC - africa, blindness, chronic infection
- D-K - urethritis/PID/ectopic, neonatal pneumonia (staccato cough) with eos, neonatal conjunctivitis (1-2 weeks after birth)
- L1-3 - lymphogranuloma venereum - painless ulcers –> swollen, painful LNs, give doxy
Gonorrhea - creamy purulent discharge
- intracellular with neutrophils
- no maltose metabolized
- condoms decrease sexual transmission, erythromycin eye ointments prevent neonatal blindness
- treat with cef
PID - CMT, Fitz-Hugh-Curtis syndrome
Mycoplasma pneumo
grown on Eaton agar, bacterial membrane contains sterols (requires cholesterol for growth)
atypical pneumo < 30 yo, in close quarters
high titer of cold agglutinins - IgM
treat with macrolides, doxy, FQ (no cell wall)
systemic mycoses
Histo < RBC = Blasto < Coccidio, Paracocidio
- cause pneumonia and can disseminate, can form granulomas
- mold in the cold, yeast in the heat
Histo - midwest (MI, OH), bird/bat droppings
- many inside macrophages
- palatal/tongue ulcers, splenomegaly
Blasto - eastern and central US, broad-based budding
- inflammatory lung disease –> skin and bone
- verrucous skin lesions ~SCC
Coccidio- SW US, spherule
- disseminates to skin/bone - erythema nodosum or multiforme, arthralgias
- meningitis
Paracoccidio - Latin Am, males
- captain’s wheel formation
fluconazole, itra- for local infection, ampho B for systemic
to summarize - it is spectrum
1) histo - lungs, mouth ulcers
2) blasto - moves to skin and bone, lesions that look like SS
3) coccidio - moves to brain (meningitis)
endotoxin
extremely heat stable
macrophage activation (TLR4) - IL1, IL6, TNFa, NO
complement activation –> C3a leads to histamine release, C5a attracts neutrophils
and tissue factor activation –> DIC
VS exotoxin - plasmid/bacteriophage
- worse than endotoxin
- less heat stable
cutaneous mycoses
tinea (dermatophytes) - branching septate hyphae, pruritis
- corporis - ring worm, can be acquired from cat/dog
- unguium - onychomycosis (ragged nails), nails
tinea (pityriasis) versicolor - Malassezia species, a yeast-like fungus (spaghetti and meatballs appearance)
- degradation of lipids –> acids –> damage to melanocytes –> patches of variable pigment
- can occur anytime - more common in summer
- treat with selenium sulfide, topical antifungals
GI protoza
Giardia - transmitted by cysts in the water
- fatty stools
- trophozoites/cysts in stool, stool antigen
- metro
Entamoeba histolytica - only one in this group that causes bloody diarrhea - flask shaped ulcers
- transmitted by cysts in water
- trophozoites with 4 nuclei or engulfed RBCs, stool antigen
- anchovy paste liver abscess, RUQ pain
- metro, parmomycin or iodoquinol for asymptomatic cyst passers
Cryptosporidium - AIDs diarrhea
- transmitted by oocysts in water - can see oocysts on acid-fast stain, stool antigen
- prevent by water filtration
- treat with nitazoxanide in immunocompetent hosts
CNS protozoa
Toxo - cysts in meat, oocysts in cat feces (preggos should avoid cats), tachyzoite (banana-shaped)
- congenital - chorioretinitis, hydrocephalus, intracranial calcifications
- AIDs - ring-enhancing lesions
- sulfadiazine and pyrimethamine
Naegleria fowleri - fatal meningoencephalitis
- Nalgene - swimming in fresh water lakes –> enters cribiform plate
- amoebas in spinal fluid
- ampho B
Trypanosoma brucei - Tsetse fly, painful bite
- enlarged lymph nodes, recurring fever (due to antigenic variation)
- will see trypomastigote in blood smear
- suramin for blood-borne, melarsoprol for CNS penetration (I sur am mel-low
other protozoa
T. cruzi - dilated (cardiomyopathy, megacolon, megaesophagus)
- unilateral periorbital swelling characteristic of acute stage
- Reduviid bug - feces
- benznidazole, nifurtimox
Leismania - sandly, macrophages will contain amastigotes
- visceral - spiking fevers, HSM, pancytopenia
- cutaneous
- ampho B, stibogluconate
ectoparasites
sarcoptes scabiei - common in kids, crowded pops, transmitted by skin-to-skin or via fomites
- mite burrows into stratum corneum - itching is worse at night, lines in webbing
- treat with permetrin cream, clean bedding
pediculus humanus/phtirus pubis = lice
- can transmit rickettsial typhus, relapsing fever (Borrelia recurrentis), or trench fever (Bartonella quintana)
- treat with pyrethroids, malathion, or ivermetin lotion
- kids can be treat at home without interrupting school attendance
complementation
like HBD and HBV
BOAR
BOAR - segmented viruses
Bunya
Flu (orthomyxoviruses) - vaccine is usually killed, live-attenuated is intranasal (temp sensitive mutant that replicates in the nose)
- antigenic SHIFT - pandemics
- orthomyxovirus - enveloped, -ssRNA, 8 segment genome
- HG binds sialic acid –> viral entry
- NA - promotes progeny virion release
- post viral - S pneumo, S aureus, H flu
Arena
Reo
Ebola and Zika
Ebola = bloody mess
- filovirus, incubates for 21 days –> abrupt onset flu
- can progress to DIC, diffuse hemorrhage, shock
- targets endothelial cells, phagocytes, hepatocytes
- transmission through body fluids, infected bats/monkeys
- ddx with RT-PCR, supportive care and isolation precautions
Zika - flavivirus, Aedes mosquito
- conjunctivitus, low-grade fever, itchy rash
- congenital microceph, miscarriages
- RT-PCR, serology
Rabies
bullet shaped virus, Negri bodies in Purkinje cells and hippocampus
skunk/raccoon bite - long incubation period
- postexposure - clean wound + immunize with killed vaccine and rabies Ig
binds to NAch receptors –> travels to CNS by migrating retrograde
fever, malaise –> agitation, photo and hydrophobia, hypersalivation –> paralysis, coma, death
enterococcus
pencillin G resistant, catalase negative, PYR pos
bacterial genetics
transformation - S pneumo, H Flu, Neisseria
- these are also the encapsulated orgs! (use polysaccharide + protein conjugate) - sickle cell pts
- also have IgA protease
type 3 secretion system - Pseudomonas, Salmonella, Shigella, E coli
osteomyelitis
S. aureus (always) or something else
cat and dog bites - Pasteurella
IVDA - Pseudomonas, Candida, S. aureus
MRI!!!
Measles and Rubella
rash begins at head and moves down - Measles rash coalesces, Rubella doesnt
Measles - paramyxovirus
- fever, cough, coryza, conjunctivitus, Koplik spots
- rash 1-2 days later
- lymphadenitis with giant cells (fused lymphocytes) - paracortical hyperplasia
- subacute sclerosing panencephalitis, giant cell pneumonia
- vitamin A supplementation can help
Rubella - postaurical LAD
- togavirus
- congenital - blueberry muffin appearance due to dermal extramedullary hematopoiesis, deafness, and cataracts
(mom will have rash, ALD, arthritis)
killed vaccines
rabies, flu, Salk, HAV
live vaccines
MMR, Chickenpox, Smallpox
Yellow fever, rotavirus
Legionella
gram negative rod, use silver stain (it is part of atypicals along with Chlamydia and Mycoplasma)
grow on charcoal yeast + Fe + cysteine
aerosol transmission from a water source - air conditioning, hot water tanks, does NOT transmit person-to-person
treat with macrolide or quinolone
Legionnaries - common in smokers and COPD-ers, severe pneumonia, GI, CNS symptoms
Pontiac fever - mild flu
b-hemolytic
S aureus, S pyogenes, S agalactiae
paramyxoviruses
cause illness in kids - parainflu, measles, mumps, RSV, human metapneumovirus
- all contain F protein –> epithelial cells fuse
- palivizumab is anti-F - prevents pneumonia cause by RSV in premies
croup - HG, NA
- stepple sign on XR, pulsus paradoxus secondary to upper airway obstruction
bacterial structures and stains
flagella - protein, pilus - glycoprotein
spore - keratin-like coat, dipicolinic acid center, gram pos only
- the only way to kill spores is by autoclaving
- cytoplasmic* membrane
- PBPs
- lipoteichoic acids - induce TNFa and IL1
giemsa - chlamydia,rickettsia, trypanosomes, plasmodium
PAS - Whipple disease
intracellular orgs - legionella, rickettsia/anaplasma/ehrlichia, chlamydia, salmonella, listeria, francisella, yersina, mycobac, brucella, coxiella, neisseria
- rickettsia, chlamydia, coxiella are obligate = need host ATP
anaerobes - foul smelling due to short-chain fatty acids)
- gram pos bac - generally facultative anaerobes
catalase pos orgs
nocardia, aspergillus, candidia
listeria, pseudomonas, h pylori
e coli, staph, serratia (red pigment), b cepacia
urease pos
kleb, proteus (swarming motility on agar), crytococcus, nocardia, s epi and sapro
naked DNA viruses
adenovirus - linear
- pharyngitis, acute hemorrhagic cystitis, pneumonia, conjunctivitis
papillomavirus - circular
polyomavirus - circular
- JC virus, BK (kidneys, transplant pts)
parvo - ssDNA, linear
picornavirus
ss RNA, nonenveloped
polio (can cause meningitis in unvaccinated kids), echo, rhino, coxsackie (A - hand-foot-mouth disease) - proteases
- viral meningitis
Rhino - binds to ICAM1, 100 serotypes, acid labile
bacteria that produce biofilms
S epi, Viridans group, P aeruginosa (respiratory tree, contact lens), unencapsulated H flu (otitis media)
lysogenic phage toxins
group A strep erythrogenic toxin, Botulism, Cholera, Diphtheria, Shiga toxin
spore formers
B. anthrax - only bacteria with a polypeptide capsule (D-glutamate), halo of projections (medusa head)
- cutaneous - painless papule surrounded by vesicles –> black eschar (painless)
- pulmonary anthrax - inhaled spores –> pulmonary hemorrhage, mediastinitis (woolsorters disease)
C. tentani
- both tetanus and botulism toxins cleave SNARE proteins
- tetanus toxin blocks release of GABA and glycine from Renshaw cells in SC
- prevent with vaccine, antitoxin, diazepam
C. botulinum
- heat labile toxin that inhibits Ach release at NMJ (floppy baby syndrome)
- diplopia, dysarthria, dysphagia, dyspnea
C. perfringens
- a toxin - lecithinase aka phospholipase –> gas gangrene, hemolysis
- heat stable enterotoxin
C. diff
- toxin A - enterotoxin that binds gut brush border, alters fluid excretion
- toxin B - cytotoxin that disrupts cytoskeleton via actin depol
- treat with metro, vanc, or fidaxomicin
C. diphtheria
g+ rod
diphtheria via exotoxin encoded by b-prophage - *inhibits protein synthesis via ADP-ribosylation of EF2
pseudomembranous pharyngitis with LAD, myocarditis, arrhythmias
black colonies on cysteine-tellurite, metachromatic granules on gram stain, Elek test for toxin
Listeria
facultative intracellular - rocket tails (actin) that allows cell-to-cell spread
dairy, deli meats
amnionitis, septicemia, spont abort, granulomatosis infantiseptica, neonatal meningitis and in immunocompromise
mild self-limiting gastroenteritis in healthy
Nocardia and Actinomyces
gram pos, filamentous rods
Nocardia
- aerobe, weakly acid fast, found in soil
- pulmonary infections in immunocompromised (can mimic TB), cutaneous infections in immunocompetent, can spread to CNS
- bactrim
Actinomyces
- anaerobe, not acid fast, normal GI flora
- oral/facial abscesses (lumpy jaw) that drain through sinus tracts - often associated with dental caries/tooth extraction
- yellow “sulfur” granules
- treat with penicillin
lactose fermenters
e coli, kleb, enterobac, serratia
e coli also produces b-galactosidase
H flu
gram neg coccobacilli, aerosol transmission, can give Hib before the age of 2
nontypable are the most common cause of mucosal infections and invasive infections
culture on chocolate agar with NAD and hematin
MOPS, epiglottitis (thumb sign on xray)
amoxicillin and clavulanate, cef for meningitis, rifampin for prophylax close contacts
N menin
polysaccharide capsule, maltose and glucose fermentation
meningococcemia with petechial hemorrhages and gangrene of toes, Waterhouse-Friderichens, meningitis
prophylax with rifampin, cipro, cef
treat with cef or penicillin G
B pertussis
g-, aerobic coccobacillus
pertussis toxin disables Gi
tracheal cytotoxin
catarrhal - low grade fevers, coryza
paroxysmal - whooping cough
convalescent - gradual recovery of chronic cough
elicits lymphocytic leukocytosis
Pseudomonas
motile, oxidase pos, grape-odor, mucoid capsule
endotoxin
exotoxin A - inactivates EF2
phospholipase C
ecthyma grangrenosum (seen in immunocompromised, rapidly progressive), osteomyelitis, otitis externa
RNA viruses
pos ssRNA - i went to a RETRO TOGA party where i drank FLAVored CORONA and ate HEPE CALI PICkles
- corona - common cold, SARS, MERS
- calcivirus - norovirus - viral gastroenteritis
- flavi - yellow fever - Aedes mosquito, human or monkey reservoir
- high fever, black vomitus, jaundice, Councilman bodies in liver - reovirus = rotavirus - most common cause of infantile gastroenteritis, daycares, villous destruction with atrophy (decreased Na in, increased K loss)
only reovirus is dsRNA
flu and retroviruses replicate outside cytoplasm
HIV
2 RNA molecules
- env - gp120 attaches to host cells (CD4 or macrophages), gp41 mediates fusion and entry
- gag - capside, matrix
- pol - RT, aspartate protease, integrase
ELISA (high false pos rate, rule out test), Western blot (rule in), viral lode (esp in neonates, where anti-gp120 crosses placenta and can give false pos)
- high false NEG in first 2 months
- neonates with HIV - chronic diarrhea
AIDs < 200
1) window period (flu like) - acute HIV infection, viral dissemination and seeding of lymphoid organs
2) latent - virus replicates in LNs
3) skin and mucosal infections
- less than 500 - candida, EBV Bartonella, HHV8, HPV
4) systemic and AIDS defining illnesses
- less than 200 - histo (oval cells within macrophages), HIV dementia, JV virus, pneumocystis
- less than 100 - aspergillus, candida, CMV (owl eye inclusions, cotoon wool spots), cryptococcus and sporidium, EBV lymphoma, MycoAC, toxo
DRUGS:
HAART - 2 NRTIs and an integrase inhibitor
NRTIs (lamivudine, tenofovir, AZT aka zidovudine) - tenofovir is a nucleoTide, all others are nucleosides
- need to phosphorylated to be active
- AZT prophylaxis during pregnancy
- abacavir contraindicated in HLA-B5701
- bone marrow suppression (give G-CSF and EPO), peripheral neuropathy, lactic acidosis, anemia (ZDV), pancreatitis (didanosine)
NNRTIs - dont require phosphorylation
- rash and hepatotox, vivid dreams with efavirenz
Protease inhibitors - navir
- ritonavir is a CYP inhibitor
- hyperglycemia, GI intolerance, lipodystrophy
- indinavir has renal effects
- use rifabutin instead of rifampin
Integrase inhbitors - increased CK
fusion inhibitors - enfuvirtide (binds gp41), maraviroc (binds CCR5 on T cells, prevents docking)
brain abscesses
staph aureus, viridans group
multiple abscesses from bacteremia
single lesions are from neighboring sites - otitis media, mastoiditis, sinusitis
penicillins cephalosporins carbapenems monobactam vanc
D-ala-D-ala structural analog
amox, amp, aminopenicillins - b-lactam sensitive
- use for enterococci, gut bacteria, and H flu
- ADRs - HSR, rash, pseudomembranous colitis
penicillinase-resistant - diclo, naf, ox have bulky R group
- interstitial nephritis
pip and tic are anti-pseudomonal
cephalosporins - bind PBPs, bactericidal
1) UTI bugs and gram pos - cefazolin (used to prevent postsurg staph a infection), cephalexin
2) fake fox fur - H flu, enterobacter, Neisseria, Serratia, UTI bugs
3) can cross BBB - meningitis, gonorrhea, lyme disease, pseudomonas
4) cefipime = g+ and g-, pseudomonas
5) ceftaroline - covers LAME bugs - listeria, atypicals, MRSA, enterococcus
- ADRs - HSR, hemolytic anemia, disulfiram-like reaction, vitamin K def, increases nephrotox of AGs
vanc binds D-ala-D-ala of cell wall, usu bacteriocidal (except with C. diff)
- nephro and ototox, thrombophlebitis, red man syndrome (prevent by slow infusion)
carbapenems + cilastin (inhibitor of renal dehydropeptidase 1) - b-lactamase resistant
- broad spectrum, last resort
- ADRs - GI distress, rash, seizures
monobactam - binds to PBP3, no cross-allergy with penicillins
- gram negative rods
- non toxic - use in renal insufficiency pts
