Microbiology Flashcards
Which part of the bacterial structure contains Beta-lactamases?
Periplasm = space between cytoplasmic membrane and peptidoglycan wall in gram (-) bacteria
*note: Beta-lactamases = hydrolytic enzymes, resistant to antibiotics
Which bacteria contain sterols, but have no cell wall?
Mycoplasma
Which bacteria has a cell wall/membrane with mycolic acid and a high lipid content?
Mycobacteria
Bugs that don’t gram stain well?
“These Rascals May Microscopically Lack Color”
- Treponema (too thin)
- Rickettsia (intracellular)
- Mycobacteria (high lipid content in cell wall; need acid-fast stain)
- Mycoplasma (no cell wall)
- Legionella (mostly intracellular)
- Chlamydia (intracellular; and lacks muramic acid in cell wall)
Giemsa stain, stains:
- Borrelia
- Trypanosomes
- Chlamydia
- Plasmodium
PAS (periodic acid-Schiff): what structures does it stain? what’s it used to dx?
“PAS the sugar” –> it stains glycogen and mucopolysaccharides!
–dx Whipple’s disease (Tropheryma whippeli)
Ziehl-Neelson stain = carbol fushsin
stains acid-fast organisms (mycobacteria)
India ink–> what organism does it stain?
stains cryptococcus neoformas
silver stain:
- Fungi (ie pneumocystis)
- Legionella
chocolate agar with factors V (NAD+) and X (hematin)
H. influenza
Thayer-Martin/VPN media (Vancomycin, Polymyxin, Nystatin)
N. gonorrhea
- vancomycin –> inhibits gram +
- polymyxin –> inhibits gram -
- nystatin –> inhibits fungi
Bordet-Gengou agar (potato agar)
Bordetella pertussis
Lowenstein-Jensen agar
M. tuberculosis
–> takes 3-4 weeks to grow though! (can do acid-fast stain in mean time to help rule out…)
Eaton’s agar
Mycoplasma pneumonia
pink colonies on MacConkey’s agar
lactose-fermenters
- MacConkey’s agar:
- biosalts and crystal violet–> inhibit gram +
- lactose–> only carb in agar
- neutral red stain–> lactose fermenters take up lactose and neutral red; form pink colonies
**non-pink growth on MacConkey’s = gram (-), but not lactose fermenter
Tellurite plate, Loeffler’s media
C. diphtheriae
Sabouraud’s agar
Fungi
Obligate aerobes:
“Nagging Pests Must Breathe”
- Nocardia
- Pseudomonas
- Mycobacterium tuberculosis
- Bacillus
Obligate anaerobes:
“Can’t Breathe Air”
- Clostridium
- Bacteroides
- Actinomyces
- **Anaerobes lack catalase and/or superoxide dismutase, so susceptible to oxidative damage
- **Aminoglycosides = ineffective against anaerobes!
- **Treat anaerobes with:
- Metronidazole
- Clindamycin
Obligate intracellular bugs:
“stay inside (cells) when it’s Really Cold”
- Rickettsia
- Chlamydia
Facultative intracellular bugs
“Some Nasty Bugs May Live FacultativeLY”
- Salmonella
- Neisseria
- Brucella
- Mycobacterium
- Listeria
- Francisella
- Legionella
- Yersinia
bugs with a positive quellung rxn?
-who’s at increased risk of infection with these organisms?
encapsulated bacteria:
- SHiN SKiS:
- S. pneumonia
- H. influenza
- Neisseria meningitidis
- Salmonella
- Klebsiella pneumonia
- group B strep
*asplenic pts –> increased risk of infection with encapsulated organisms
Catalase-positive organisms:
-which pts have recurrent infections with these organisms?
- S. aureus
- Serratia
- Pseudomonas
- Candida
- E. coli
*pts with chronic granulomatous disease (NADPH oxidase deficiency) have recurrent infections with these organisms
Urease-positive bugs
“K-PUNCH”
- Klebsiella
- Proteus
- Ureaplasma
- Nocardia
- Cryptococcus
- H. pylori
*Urease splits urea into ammonium, which binds Mg and P –> forms stones –> stones deposited in renal calyces
Protein A
S. aureus virulence factor; binds Fc region of Ig; prevents opsonization and phagocytosis
IgA protease
virulence factor of SHiN: S. pneumonia, H. influenza, Neisseria
–> enzyme that cleaves IgA in order to colonize respiratory mucosa
M protein
virulence factor of Group A Strep: helps prevent phagocytosis
*Note: antibodies to M protein enhance host defenses against GAS, but can give rise to Rheumatic fever…
Which 2 bacteria produce a toxin that inhibits protein synthesis by inactivating elongation factor, EF-2?
C. diphtheriae –> Diphtehria toxin
Pseudomonas aeruginosa –> Exotoxin A
Which 2 bacteria produce a toxin that inhibits protein synthesis by inactivating the 60S ribosome by cleaving rRNA?
Shigella –> Shiga toxin
EHEC (including O157:H7) –> Shiga-like toxin
List 5 bacteria that produce an ADP-ribosylating A-B toxin:
1) Corynebacterium diphtheriae
2) Pseduomonas aeruginosa
3) ETEC
4) Vibrio cholerae
5) Bordetella pertussis
***Mechanism: B-binding component binds host cell surface receptor, enabling endocytosis; A-active component attaches ADP-ribosyl to disrupt host cell proteins
Which 2 bacteria produce a heat stable toxin? What’s the mechanism?
ETEC and Yersinia enterocolitica
*mechanism: increased cGMP –> decreased reabsorption of NaCl and H20 in gut –> increased fluid secretion
- note:
- ETEC –> watery diarrhea
- Yersinia –> bloody diarrhea
Which E. coli has a toxin that functions by the same mechanism as the cholera toxin? What’s the mechanism?
ETEC - heat labile toxin
*mechanism: increased cAMP by permanently activating Gs –> increased Cl secretion in gut and H20 follows it –> so increased fluid secretion
Which bacteria has a toxin that mimics adenylate cyclase (toxin acts like the enzyme!)?
Bacillus anthracis: toxin= edema factor –> mimics adenylate cyclase –> increased cAMP –> increased fluid secretion
2 toxins produced by ETEC (enterotoxigenic E. coli) and their mechanisms?
- heat labile toxin: increases adenylate cylcase–> increased cAMP–>iincreased Cl secretion in gut –> increased H20 secretion
- heat stabile toxin: increases guanylate cyclase –> increased cGMP –> decreased reabsorption of NaCl and H20 in gut
Which 2 bacteria produce a toxin that cleaves SNARE protein required for neurotransmitter release (and thereby inhibit release of neurotransmitter)?
Clostridium tetani and Clostridium botulinum
Which bacterial toxin acts through this mechanism?
–> overactivates adenylate cyclase by inhibiting Gi–> increased cAMP –> thereby, impairs phagocytosis, permitting survival of microbe
Pertussis toxin (Bordatella pertussis)
Tetanospasmin toxin: which neurotransmitters does it affect and how? what are the manifestations?
-tetanospasmin prevents release of inhibitory neurotransmitters (GABA and glycine) –> get muscle rigidity and “lock jaw”
Botulinum toxin: which neurotransmitters does it affect and how? what are the manifestations?
botulinum toxin prevents the release of stimulatory (Ach) signals at neuromuscular junctions –> get flaccid paralysis, “floppy baby”
Which bacteria produces Alpha toxin/Lecithinase (degrades phophospolipids)
Clostridium perfringens
-degradation of phospholipids–> myonecrosis (gas gangrene) and hemolysis (double zone of hemolysis on blood agar)
Streptolysin O toxin: mechanism?
- Streptococcus pyogenes (Group A strep)
- toxin lyses RBCs, contributes to Beta-hemolysis
- ASO antibodies can be used to dx rheumatic fever
Which 2 organisms have superantigens? what are the toxins? superantigen mechanism?
- Group A strep (Strep pyogenes) –> Exotoxin A
- Staph aureus –> TSST-1 (toxic shock syndrome toxin)
*superantigens bind MCH II and TCR simultaneously to stimulate a huge release of IL-2 and IFN-gamma –> results in shock; both can cause toxic shock syndrome (fever, rash, shock)
bacterial “competence”
-which bacteria are “competent?
competence = ability to take up DNA from environment = transformation (in bacterial genetics)
-many bacteria can undergo transformation, but especially common in SHiN (S. pneum, H. infl, Neisseria)
Conjugation: (F+ X F-) vs (Hfr X F-)?
(F+ X F-): only plasmid DNA can be transferred this way
(Hfr X F-): Transfer of plasmid AND chromosomal genes (because F+ plasmid can become incorporated into bacterial chromosomal DNA –> “Hfr cell”
Transduction:
bacterial genetic term –> spread of bacterial DNA via lytic (“generalized transduction”) or lysogenic (“specialized transduction”) bacteriophage (virus that infects bacteria)
What makes MRSA resistant to Beta-lactams?
Altered penicillin-binding protein
rusty sputum
pneumococcus! (strep pneumonia)
Strep pneumonia = most common cause of:
- Meningitis
- Otitis media (in kids)
- Pneumonia
- Sinusitis
Bacteria that causes acute bacterial endocarditis?
Staph aureus
Bacteria that causes subactue bacterial endocarditis at damaged valves?
-Strep sanguis (viridans group strep)
think of the sanguinistas in true blood :)
strawberry tongue
Scarlet fever –> toxigenic effect of group A strep
about 15% of colon cancer pts are colonized by which strep?
strep bovis (group D strep)
ABCDEFG of Corynebacterium diphtheriae
ADP ribosylation Beta-prophage (encodes exotoxin) Corynebacterium Diphtheria Elongation Factor 2 Granules (dx by gram + rods with metachromatic -blue and red- granules)
*exotoxin encoded by a beta-prophage–> exotoxin inhibits protein synthesis via ADP ribosylation of EF2
Spore-forming bacteria:
certain gram + rods:
- main ones:
- Bacillus anthracis
- Clostridium perfringens
- Clostridium tetani
- also:
- Bacillus cereus
- Clostrium botulinum
- Coxiella burnetti
Prevents glycine and GABA and glycine release from Renshaw cells in spinal cord?
Tetanospasmin (Clostridium tetani toxin) –> blocks inhibitory neurotransmitters, so causes spastic paralysis, trismus (lockjaw) and risus sardonicus
Treatment of C. difficile?
metronidazole or oral vancomycin (only case in which vancomycin is given orally!)
2 toxins produced by C. difficile, and how do they act?
Toxin A = enterotoxin: binds brush border of gut
Toxin B = cytotoxin: destroys cytoskeletal structure of enterocytes, causing necrosis of colon epithelium = pseudomembranous colitis
Only bacterium with a polypeptide capsule (that contains D-glutamate)?
Bacillus anthracis
move from cell to cell via “actin rockets”; bacteria is acquired by ingestion of unpasteurized milk/cheese and deli meats, or by vaginal transmission during birth
Listeria monocytogenes
treatment of actinomyces vs nocardia?
“ooooh SNAP!”
- Sulfa for Nocardia
- Actinomyces - use Penicillin
Langhans giant cells –> see multiple peripheral nuclei organized in the shape of a horseshoe
characteristic of TB caseating granulomas
Extrapulmonary tuberculosis:
- CNS–> tuberculoma or meningitis
- Pott’s disease in vertebral bodies
- lymphadenitis
- renal
- GI
Ghon complex =
-TB granulomas
= Ghon focus (calcified scar, usually in lower lobes) + lobar and perhilar lymph node involvement; reflects primary infection or exposure
Mycobacterium kansasii
pulmonary TB-like symptoms; more common in pts with COPD (chronic bronchitis or emphesyma)
Prophylactic treatment for Mycobacterium avium-intracellulare?
- Azithromycin
- ->MAI is often resistant to many drugs; causes disseminated disease in AIDS pts.
Reservoir in US is armadillos?
Mycobacterium leprae (Leprosy = Hansen’s disease)
Treatment for leprosy?
- long term oral Dapsone (but, toxicity = hemolysis and methemoglobinemia)
- alternatively: rifampin, or combination of clofazimine and dapsone
Lactose-fermenting bacteria (grow pink on MacConkey’s agar)…
macConKEES or CEEKS:
- Citrobacter
- Klebsiella
- E. coli
- Enterobacter
- Serratia
*note: E. coli produces Beta-galactosidase–> breaks lactose into glucose and galactose!
Which class of bacteria are resistant to Penicillin G (or rather, which class can Penicillin G be used to treat)?
Gram (-) bacilli are resistant to Penicillin G (but, may be susceptible to penicillin derivatives)
Penicllin G and V are mostly used to treat gram (+) organsims, and syphilis!
Fitz-Hugh-Curtis syndrome
caused by N gonorrhea
–>stars in lower genital tract, ascends through upper genital tract, ultimately infects liver capsule
Treatment for N. gonorrhea?
ceftriaxone
Waterhouse-Friderichsen syndrome
caused by N. meningitidis
–>adrenal hemorrhage –> adrenal insufficiency –> hypotension + DIC + electrolyte abnormalities
Prophylaxis and treatment for N. meningitidis?
- Vaccine available (not for type B)
- Rifampin prophylaxis in close contacts
- Treatment: ceftriaxone or penicillin G
Why can H. influenza be grown with Staph aureus?
H. infl requires Factors V (NAD+) and X (hematin) for growth; S. aureus provides factor V!
Prophylaxis for H. influenza?
Treatment for meningitis caused by H. infl?
- Vaccine: type B capsular polysaccharide conjugated to diphtheria toxoid or other protein
- Prophylaxis in close contacts: Rifampin
- Treatment for meningitis: Ceftriaxone
Legionnaires disease vs Pontiac fever?
Both caused by Legionella pneumophila
- Legionnaires’ disease = severe pneumonia and fever
- Pontiac fever - mild flu-like syndrome
***suspect Legionella in pts with recent exposure to contaminated water (ie cruise ship, hotel, etc…)
pt with Cystic Fibrosis + Pneumonia?
Pseudomonas
PSEUDOM of pseudomonas (presentations):
- Pneumonia (especially in cystic fibrosis pts)
- Sepsis (black lesions on skin–> ecthyma gangrenosum = cutaneous necrotic disease, common in imm-compromised pts)
- External otitis (swimmer’s ear)
- UTI
- Drug use endocarditis and Diabetic Osteomyelitis
- Malignant otitis externa in diabetics
- ->also: hot tub folliculits
- assoc with wound and burn infections
- water source
- produces pyocyanin = blue-green pigment
- grapelike odor
Treatment for Pseudomonas?
Aminoglycoside + extended-spectrum penicillin (ie piperacillin or ticarcillin)
E. coli virulence factors: What do they cause?
- Fimbriae?
- K capsule?
- LPS?
Fimbriae –>cystitis and pyelonephritis
K capsule –> pneumonia, neonatal meningitis
LPS –> septic shock
Anemia + Thrombocytopenia + Acute Renal Failure?
HUS = hemolytic uremic syndrome (EHEC O157:H7)
Which E. coli strain is the only one that does not ferment sorbitol?
EHEC
Which E. coli strains cause bloody diarrhea?
EIEC and EHEC
Which E. coli strain normally causes diarrhea in children?
EPEC (P for pediatrics :))–> doesn’t produce toxin; adheres to apical surface, flattens villi, prevents absorption
Which E. coli strains produce a toxin (and what toxin is it?) Which do not produce toxin?
EIEC –> no toxin
ETEC –> heat labile and heat staible toxins
EPEC –> no toxin
EHEC –> shiga-like toxin
Which antibiotic should be used to treat Salmonella?
TRICK QUESTION! Do not treat Salmonella with antibiotics; antibiotics may prolong symptoms!
Osteomyelitis in a sickle cell patient?
Think Salmonella!
spots on abdomen + fever + headache + diarrhea?
Salmonella typhi (rose spots on abdomen)
Which is more virulent: Shigella or Salmonella?
Shigella is more virulent –> only takes
10^1 organisms for infection, vs Salmonella –> takes 10^5 organisms!
Which bacterial infection is associated with Reiter’s syndrome/Reactive arthritis?
- Shigella flexneri
- Chlamydia
Causes mesenteric adenitis (which may mimc Crohn’s or appendicitis)?
Yersinia enterocolitica! (transmitted from pet fecies, contaminated milk, pork; outbreaks of diarrhea in daycare centers…)
Triple therapy for H. pylori treatment:
1) PPI
2) Clarithromycin (macrolide)
3) Amoxicillin or Metronidazole
- **Quadruple Therapy:
- Bismuth salicylate
- Metronidazole
- PPI
- Tetracylcine
flulike symptoms, jaundice, and photophobia with conjunctivitis, in person who was in contact with animal urine?
Leptospirosis (Leptospira interrogans)
–> severe form = Weil’s disease
Weil’s disease
=Icterohemorrhagic Leptospirosis
–> severe form of Leptospirosis (Leptospira interrogans): jaundice and azotemia (from liver and kidney dysfxn); fever, hemorrhage, anemia
water contaminated with animal urine? Think:
- Leptospira
- Hantavirus
Ixodes tick
vector for:
- Lyme disease (Borrelia burgdorferi)
- Babesia
3 stages of lyme disease:
“BAKE a key Lyme pie!” (Bell’s palsy, Arthritis, Kardiac block, Erythema migrans)
Stage 1: erythema chronicum migrans (bull’s eye rash), flu-like symptoms
Stage 2: Neurologic (bilateral or unilateral Bell’s palsy) and Cardiac (AV nodal block) manifestations
Stage 3: chronic monarthritis and migratory polyarthritis
Treatment for Lyme disease: at early stages (1 and 2)? Later disease?
Doxycycline –> for early stages
Ceftriaxone –> later disease
Treatment of choice for Syphilis?
Penicillin G!
primary syphilis:
painless chancre (localized)
secondary syphylis:
(secondary = systemic) disseminated disease with constitutional symptoms
- maculopapular rash (palms and soles)
- condyloma lata
- visualize treponemes from chancres and condyloma lata by darkfield microscopy
tertiary syphilis
- gummas (chronic granulomas)
- aortitis (VASO VASORUM DESTRUCTION!)
- neurosyphilis = tabes dorsalis
- Argyll Robertson pupil
- Signs: ataxia, + Romberg, Charcot joint, stroke but no HTN
FTA-ABS
test used to confirm syphilis (screening test = VDRL)
CN VIII deafness in a neonate?
Congenital syphilis (other signs = saber shins (ant bowing of tibia), saddle nose (flat nasal bridge), Hutchinson’s teetch (notching of upper incisors), mulberry molars)
What may cause a false positive VDRL (screening test for syphilis)?
Viruses (mono, hepatitis)
Drugs
Rheumatic fever
Lupus and Leprosy
- note: VDRL detects a nonspecific antibody that reacts with beef cardiolipin
- can confirm dx of syphilis with FTA-ABS
Transmitted by lice/louses?
Borrelia recurrentis and Rickettsia rickettsii
Transmitted by spores from tick feces and cattle placenta?
Coxiella burnetti –> causes Q fever
transmitted by animal/cat/dog bites? symptoms?
Pasteurella multocida –> cellulitis, osteomyelitis
Transmitted by fleas?
Rickettsia typhi, Yersinia pestis (Yersinia is also transmitted by rodents, prairie dogs…)
Treatment for all Rickettsial diseases?
Doxycycline
Headache + Fever + Rash that starts on palms and soles?
Rickettsia rickettsii = Rocky Mountain spotted fever (transmitted by tick)
Headache + Fever + Rash that starts centrally and spreads outward without involving palms or soles?
Rickettsia typhi = Rickettsia prowazekii (transmitted by louse) –> “Typhus on Trunk”
Q fever
- presents as pneumonia
- caused by Coxiella burnetti (part of Rickettsia)
- “Queer” b/c:
- no rash
- no vector (transmitted by inhaling aerosoles from ticks feces or cattle placenta)
- negative Weil-Felix
- no “Rickettsia” in genus name
Weil-Felix Reaction
DX Rickettsia (not Coxiella though)–> mix pt’s serum (with anti-Rickettsial antibodies) with Proteus antigens –> antirickettsial antibodies cross-react to Proteus O antigens and agglutinate
Cytoplasmic inclusions seen on Giemsa or Fluorescent antibody-stained smear
Lab dx for Chlamydia
Treatment for Chlamydia?
- 1st line = Azithromycin
- Or: Doxycyline
Chlamydia: What is associated with each types:
- A, B, C:
- D-K:
- L1, L2, L3
- A, B, C: blindness in Africa, chronic infection
- D-K: urethritis, PID, ectopic pregnancy, neonatal pneumonia, neonatal conjuctivitis
- L1, L2, L3: lymphogranuloma venereum (acute lymphadenitis)
3 main organisms that cause interstitial/atypical/walking pneumonia?
- Chlamydia pneumonia
- Mycoplasma pneumonia (most common)
- Legionella pneumophila
RBC agglutination or lysis in cold temperatures?
Mycoplasma pneumonia –> cold agglutinins (IgM)
–> this happens b/c Mycoplasma pneumonia shares antigens with human RBCs, so when body mounts a response against antigens, it also lyses RBCs, leading to anemia; antibodies that cause this RBC destruction = cold agglutinins
only bacterial membrane that contains cholesterol?
Mycoplasma pneumonia
Treatment for Mycoplasma pneumonia?
tetracycline or erythromycin
5 Infections associated with birds:
1) Histoplasmosis –> pneumonia
2) Cryptococcus –> meningitis in AIDS pts
3) Chlamydia psittaci –> atypical pneumonia
4) Avian influenza
5) West Nile Virus
Exotoxin A
2 organisms have an exotoxin A:
- Pseudomonas (similar to diphtheria toxin, inactivates EF2)
- Group A Strep (similar to TSST1of Staph aureus –> superantigen, causes shock)
*note: there’s also an alpha toxin (lecithinase) that Clostridium perfringens has…
Pneumonia, after pt was in:
1) Mississippi or Ohio river valleys
2) States east of Mississippi River and Central America
3) Southwestern US, California
4) Latin America
1) Histoplasmosis
2) Blastomycosis
3) Coccicidomycosis
4) Paracoccidioidomycosis
Dimorphic fungi: List them. What do they all cause? What makes them dimorphic?
- all cause pneumonia and can disseminate
- dimorphic: mold in cold (20 degrees); yeast in heat (37 degrees); exception = coccidiomycoides = spherule (not yeast) in tissue
- Includes:
1) Histoplasmosis
2) Blastomycosis
3) Coccidioidomycosis
4) Paracoccidioidomycosis
pneumonia-causing fungi that forms spherules filled with endospores in tissues (much larger than RBCs)
Coccidioidomycosis
meningitis, pneumonia, and dissemination to bone and skin following an earthquake?
Coccidioidomycosis
Budding yeast with “captain’s wheel” appearance?
Paracoccidioidomycosis
spaghetti and meatball appearance on KOH prep
Tinear versicolor (caused by Malassezia furfur); degrades lipids and produces acids that damage melanocytes –> so get hypopigmented and/or hyperpigmented patches
Dimorphic yeast: pseduohyphae and budding yeasts at 20 C; germ tubes at 37 C
Candida albicans
Branching septate hyphae that branch at acute angles, not dimorphic. Get a “fungus ball”
Aspergillus fumigatus (especially in immunocompromised pts or pts with Chronic granulomatous disease)
Heavily encapsulated yeast (budding yeast form only); have wide capsular halos and unequal budding
Cryptococcus
Meningitis in AIDS pt?
Cryptococcus
“soap bubble” lesions in brain?
Cryptococcus
How do you culture Cryptococcus? Stain?
Culture on Sabourad’s agar
Stain with India ink
nonseptate hyphae that branch at wide angles?
Mucor and Rhizopus species (Mucormycosis)
Fungus that causes a black necrotic eschar on face?
Mucor and Rhizopus
Fungus that penetrates cribriform plate and enter brain –> get frontal lobe abscesses, headache, facial pain, maybe cranial nerve involvement?
Mucor and Rhizopus
disk-shaped yeast on methenamine silver stain?
Pneumocystis jiroveci
When do you start PCP prophylaxis in HIV pt?
when CD4 < 200 cells/mm3
Dimophic, cigar-shaped budding yeast that causes ascending lymphangitis
Sporothrix schenckii = rose gardner’s disease
Severe diarrhea in AIDS pt?
Cryptosporidium
infant born with triad of: chorioretinitis, hydrocephalus, intracranial calcifications?
congenital toxoplasmosis
transmission by Tsetse fly; painful bite
-Trypanosoma brucei (gambiense, rhodesiense); causing African sleeping sickness (enlarged lymph nodes, recurring fever, somnolence, coma)
Transmitted by Anopheles mosquito
Plasmodium (malaria)
When do you give Primaquine and why?
Give to pts with Plasmodium vivax/ovale –> because there’s a dormant form that lives in liver (hypnozoite) that chloroquine/mefloquine can’t get.
“maltese cross” on blood smear?
Babesiosis (transmitted by Ixodes tick, same as Lyme disease)
transmitted by Reduviid bug (painless bite)
Trypanosoma cruzi = Chaga’s disease
Achalasia (dilated esophagus and absent peristalsis in esophagus), and dilated cardiomyopathy
Chagas disease (also may have megacolon)
spiking fevers, hepatosplenomegaly, pancytopenia; and “amastigotes” within macrophages?
visceral Leishmaniasis = “kala-azar
transmitted by sandfly?
Leishmaniosis
most common nematode infection in US?
Enterobius vermicularis = pinworm! test with scotch tape test (best!!)
1/3rd of world’s popl is infected with this worm?
Ascaris lumbricoides = giant roundworm
Nematodes that can cause anemia?
Ancylostoma, Necator (hookworms)
Treatment for Intestinal nematode infections?
- bendazoles
- pyrantel pamoate
transmitted by female blackflies?
-Onchocerca volvulus
causes hyperpigmented skin and river blindness?
Onchocerca volvulus (blackflies, black skin, black visions)
Treatment for Onchocerca volvulus?
Ivermectin (for river blindness!)
can see worm crawling in conjunctiva?
Loa Loa
Elephantiasis (appears about 1 year post bite by mosquito)
Wuchereria bancrofti
Transmitted by eating larvae in pork: get cysticercosis and neurocysticercosis, mass lesions in brain (with swiss cheese appearanc) –> seizures, altered mental status, coma…
Taenia solium
Ingest larvae in raw freshwater fish; causes B12 deficiency
Diphyloobothrium latum
causes anaphylaxis if organism’s antigens are released from cysts (so must kill daughter cysts before attempting to remove surgically)
Echinococcus granulosus
snails are the host
Schistosoma
inflammation of spleen and liver; can lead to squamous cell carcinoma of bladder
Schistosoma
Nematodes routes of infection:
- ingested?
- cutaneous?
Ingested: “EAT” these:
- Enterobius
- Ascaris
- Trichinella
Cutaneous: get into your feet through the “SANd”
- Strongyloides
- Ancylost`oma
- Necator
Parasite hint: brain cysts, seizures
Taenia solium (cysticercosis)
Parasite hint: liver cysts
Echinococcus granulosus
Parasite hint: B12 deficiency
Diphyllobothrium latum
Parasite hint: Biliary tract disease, cholangiocarcinoma
Clonorchis sinensis
Parasite hint: portal hypertension
schisto
Parasite hint: hematuria, bladder cancer
schisto
Parasite hint: perianal pruritus
Enterobius
Live-attenuated vaccines:
“Live! see Small Yellow Chickens get vaccinated with Sabin’s and MMR!”
- smallpox
- yellow fever
- chickenpox (VZV)
- Sabin’s (polio)
- MMR
- also: intranasal influenza vaccine
Killed vaccines:
“RIP Always”:
- Rabies
- Influenza (intramuscular)
- Polio – salk (SalK = Killed)
- HAV
Recombinant vaccines
HBV (recombinant HBsAg angtigen)
HPV (types 6, 11, 16, 18)
What HPV strains are in the vaccine?
6, 11, 16, 18
Only DNA virus that is ssDNA (the rest are dsDNA)
Parvovirus (part-of-a-virus)
Only RNA virus that is dsRNA (the rest are ssRNA!)
Reovirus (“repeat-o-virus”)
All viruses are haploid (1 copy of DNA or RNA) except?
Retroviruses: have 2 identical ssRNAs
Where do DNA viruses replicate? exception?
Nucleus (except poxvirus replicates in cytoplasm)
Where do RNA viruses replicate? Exception?
Cytoplasm (except influenza virus and retroviruses –> in nucleus)
Naked/Non-enveloped viruses:
“Naked CPR and PAPP smears!” (PAPP=DNA; CPR = RNA)
- Calcivirus
- Picornavirus
- Reovirus
- Parvovirus
- Adenovirus
- Papilloma
- Polyoma
List the DNA viruses
DNA viruses are “HHAPPPPy!”
- Hepadnavirus
- Herpesvirus
- Adenovirus
- Parvovirus
- Poxvirus
- Polyomavirus
- Papillomavirus
General rules about DNA viruses (and exceptions):
All DNA viruses are:
- dsDNA (except Parvovirus)
- liner (except Polyoma, Papilloma, and Hepadna)
- icosahedral (except Pox)
- replicate in nucleus (except Pox)
Acute hemorrhagic cystitis (hematuria + dysuria), febrile pharyngitis
Adenovirus
Aplastic crisis in sickle cell pt?
Parvovirus B19
Progressive multifocal leukoencephalopathy (PML) in HIV pts?
JC virus (Polyomavirus)
flesh-colored dome lesions with central lesion; resolves on own (usually)
molluscum contagiosum (poxvirus)
Where are these herpesviruses latent?:
- HSV1
- HSV2
- VZV
- EBV
- CMV
- HSV1–> trigeminal ganglia
- HSV2 –> sacral ganglia (S2 and S3)
- VZV –> trigeminal or dorsal root ganglia
- EBV–> B cells
- CMV –> mononuclear cells
Cancers associated with EBV?
- Burkitt’s lymphoma, Hodgkin’s lymphoma
- Nasopharyngeal carcinoma
Roseola
HHV-6 “sixth disease”
–> high fevers for several days, followed by diffuse macular rash
What are the atypical lymphocytes in EBV?
NOT infected B cells! They’re activated CD8+ cytotoxic T-cells–> “Downy cells” with foamy cytoplasm
Which HPV strains are associated with warts? CIN, cervical cancer?
Warts: 1, 2, 6, 11
CIN/Cervical cancer: 16, 18
1 cause of fatal diarrhea in kids? (fatal by dehydration)
Rotavirus (a Reovirus)
List the Picornaviruses:
"PERCH" Poliovirus Echovirus Rhinovirus Coxsackievirus Hep A virus
Norwalk virus
A calcivirus
–> viral gastroenteritis
List the Flaviviruses:
HCV Yellow Fever Dengue St. Louis encephalitis West Nile virus (all are arboviruses, except for HCV)
List the Togaviruses:
Rubella (German measles)
Eastern equine encephalitis
Western equine encephalitis
What does Coronavirus cause?
- Common Cold
- SARS
Influenza virus is part of what viral family?
Orthomyoxvirus
Paramyxoviruses
Parainfluenza = croup
RSV–> bronchiolitis in babies
Rubeola = Measles
Mumps
Negative-stranded viruses:
have to transcripe (-) strand to (+); so, bring their own RNA-dep-RNA-pol. Includes: “Always Bring Polymerase Or Fail Replication”
- Arenaviruses
- Bunyaviruses
- Paramyxoviruses
- Orthomyxoviruses
- Filoviruses
- Rhabdoviruses
Segmented viruses:
“BOAR”
- Bunyaviruses
- Orthomyxoviruses (influenza!)
- Arenaviruses
- Reoviruses
Most common cause of viral aseptic meningitis?
Enteroviruses (the Picornaviruses, minus Rhinovirus; specifically: Echovirus and Coxsackievirus)
Which part of spinal cord does poliovirus affect?
Affects MOTOR neurons of the ANTERIOR horn; causes paralysis
Transmitted by the Aedes mosquito?
Yellow Fever virus (a Flavivirus)
High fever + black vomitus (coffee-ground emesis) + Jaundice + red tongue with white center
Yellow Fever (Flavivirus, transmitted by Aedes mosquito) --> black vomitus is from GI bleeding
How does Rotavirus lead to diarrhea?
Villous destruction with atrophy, leads to decreased absorption of Na+ and H2O
–> it’s fatal by dehydration
Hemagglutinin and Neuraminidase
Influenza antigens:
- HA–> promotes viral entry
- NA–> promotes progeny virion release
F (fusion) protein
Surface protein of Paramyxoviruses –> causes respiratory epithelial cells to fuse and form multinucleated giant cells
–> Palivizumab = monoclonal antibody against F protein; prevents pneumonia in premature infants
Low-pitched cough vs High-pitched cough
Low-pitched –> Seal-like barking cough = Croup = Paraifluenza
High-pitched –> RSV
Palivizumab
monoclonal antibody against the F protein of Paramyxoviruses; given to premature infants to prevent pneumonia from RSV
Cough + Coryza (nasal, cold symptoms) + Conjunctivitis
Measles
Mumps causes:
“POM”
- Parotitis
- Orchitis
- aseptic Meningitis
–> may lead to infertility after puberty
cytoplasmic inclusions in Purkinje cells of cerebellum
Negri bodies of Rabies (commonly found in Purkinje cells of cerebellum)
virus travels to CNS by migrating in a retrograde fashion up nerve axons
Rabies virus
What kind of Polymerase does HBV carry?
DNA-dep-DNA-pol
HBsAg
Hepatitis B infection
anti-HBsAg
immunity to Hep B (vaccine or recovered from disease)
HBeAg
active viral replication; high transmissibility
anti-HBeAg
low transmissibility
HBcAg
can’t see this in serum; but, indicates new disease
anti-HBcAg: IgM? IgG?
IgM –> acute/recent infection
IgG –> chronic disease
*Positive during window period
*not present if vaccinated; only if have/had disease
ALT:AST in viral hepatitis? alcholic hepatitis?
alcoholic hepatitis: AST>ALT
viral hepatitis: ALT>AST
HIV envelope proteins:
gp120 and gp41: acquired from budding through host cell plasma membrane:
gp120–> attachment to host cell; “docking glycoprotein”
gp41–> fusion and entry; transmembrane glycoprotein
HIV capsid protein
gag (p24)
HIV pol protein:
Reverse transcriptase (synthesizes dsDNA from RNA)
What does HIV bind on T-cells? on macrophages?
T-cells: HIV binds CXCR4 or CCR5 co-receptor and CD4
Macrophages: CCR5 and CD4
Why do ELISA/Western blot tests often give false-positives in babies born to HIV-infected mothers?
Because anti-gp120 can cross the placenta
HIV diagnosis: Which test is initially used? Then which test is used to confirm positive results?
1) ELISA –> high false positive rate (high sensitivity, low specificity; “Rule out” test)
2) Western blot assay (high false negative rate; high specificity, low sensitivity; “rule in” test)
3 ways to dx AIDS:
1) CD4 < or = 200
2) AIDS indicator condition in HIV + pt: ie PCP
3) CD4/CD8 ratio < 1.5
chronic watery diarrhea in AIDS pt
Cryptosporidium (see acid-fast cysts in stool, esp when CD4<200)
Encephalopathy in AIDS pt
JC virus reactivation (get demyelination)
Neuro Abscesses in AIDS pt
Toxoplasmosis (ring-enhancing lesions; CD4<100)
Meningitis in AIDS pt
Cryptococcus (may also cause encephalitis; india ink stain –> see yeast with narrow-based budding and large capsule; CD4<50)
Retinitis in AIDS pt
CMV (cotton-wool spots on funduscopic exam; may also have esophagitis; CD4<50)
Dementia in AIDS pt
Directly associated with HIV; but, rule out other causes
AIDS pt with superficial vascular proliferation: Biopsy shows neutrophilic inflammation? lymphocytic inflammation?
- Neutrophilic inflammation –> “Bacillary angiomatosis” –> Bartonella henselae
- Lymphocytic inflammation –> HHV-8 = Kaposi’s sarcoma
low fevers, cough, hepatosplenomegaly, tongue ulcer (basically, systemic disease) in AIDS pt?
Histoplasmosis (see oval yeast cells within macrophages)
Hairy leukoplakia (white stuff on lateral part of tongue) in AIDS pt
EBV
Primary CNS lymphoma in AIDS pt
EBV
Interstitial pneumonia (with intranuclear inclusion bodies on biopsy) or regular pneumonia (esp with CD4<200) in AIDS pts?
- Interstitial pneumonia with owl’s eye inclusion bodies –> CMV
- Pneumonia with CD4 PCP
Pleuritic pain, Hemoptysis, infiltrates on imaging in AIDS pt
Invasive Aspergillosis
TB-like disease in AIDS pts (esp CD4<50)
Mycobacterium Avium - Intracellulare
3 bugs that can cause mesenteric adenitis (so may mimic appendicitis):
- Yersinia enterocolitica
- Campylobacter
- non-typhoidal Salmonella
Bloody Diarrhea…
is SEEECSY!
- Salmonella
- EHEC
- EIEC
- Entamoeba
- Campylobacter
- Shigella
- Yersinia
Causes of watery diarrhea?
- ETEC
- C. diff
- C. perfringens
- Cholera
- Protozoa: Giardia and Cryptosporidium (in imm-compromised)
- Viruses: Rotavirus, Adenovirus, Norwalk virus
3 main causes of atypical pneumonia:
- Mycoplasma
- Legionella
- Chlamydia
Cause of osteomyelitis in most pts?
S. aureus
Cause of vertebral osteomyelitis?
M. tb (Pott’s disease)
Cause of osteomyelitis in Sickle cell pt?
Salmonella
Elderly pt with delirium?
UTI or anti-cholinergic drugs side effects
Positive nitrite test
Specific for gram (-) bacterial UTI
Positive leukocyte esterase test
non-specific for bacterial UTI
UTI -causing bug; motile, so “swarms” on agar; produces urease, and associated with struvite stones
Proteus
Hydrops fetalis in utero cause?
Parvovirus B19
neonate with chorioretinitis + hydrocephalus + intracranial calcifications?
congenital Toxoplasma
Neonate with PDA (or pulmonary artery hypoplasia) + cataracts + deafness +/- “blueberry muffin” rash (purpura d/t thrombocytopenia)
congenital Rubella
Neonate with unliateral hearing loss + seizures + petechial rash + “blueberry muffin” rash
congenital CMV
Neonate with temporal encephalitis and vesicular lesions
congenital HSV-2
often results in stillbirth, hydrops fetalis; if infant is born: facial abnormalities, CN VIII deafness, teeth issues… etc…
congenital Syphilis
Rubella, Rubeola, Roseola
- Rubella = “German measles” –> rash begins at head and moves down; have a truncal rash; post-auricular lymphadenopathy
- Rubeola = Measles –> first: cough, coryz, conjunctivitis, Koplik spots on tongue; then: rash starts at head and moves down
- Roseola = HHV-6: macular rash over body after several days of high fever; usually in infants
Erythematous, sandpaper-like rash with fever and sore throat
Scarlet Fever (GAS)
vesicular rash on palms and soles; ulcers in mouth
Hand-Foot-Mouth disease (Coxsackie A virus)
strawberry-colored cervical mucosa, corkscrew motility on wet prep, vaginitis
Trichomoniasis
Koilocytes
look like fried eggs! (squamous cells with perinuclear cytoplasmic clearing)
–> HPV 6 and 11
Most common bacterial STD in US?
Chlamydia trachomatosis
Antibiotics/anti-microbials that should NOT be taken during pregnancy:
“Countless SAFe Moms Take Really Good Care”
- Clarithromycin
- Sulfonamides –> kernicterus
- Aminoglycosides –> ototoxicity
- Fluoroquinolones –> cartilage damage
- Metronidazole –> mutagenesis
- Tetracyclines –> discolored teeth, inhibition of bone growth
- Ribavirin (antiviral) –> teratogenic
- Griseofulvin (anti-fungal) –> teratogenic
- Chloramphenicol –> “gray baby”
Side effects: Hyperglycemia, Lipodystrophy (deposition of fat on back and abdomen), Nausea, Diarrhea
HIV: Protease inhibitors (all end in “-navir”
HIV drug that can cause nephrotoxicity and nephrolithiasis
Indinavir (protease inhibitor)
HIV drug that can cause pancreatitis
Ritonavir (protease inhibitor)
HIV drugs that lead to bone marrow suppression
NRTIs (nucleoside reverse transcriptase inhibitors) –> especially Zidovudine (ZDV), but all of them…
HIV drug that can cause megaloblastic anemia
ZDV (Zidovudine), a NRTI
Protease inhibitors mechanism:
Inhibit HIV-1-protease (pol gene) from cleaving the polypeptide products of HIV mRNA into functional parts, so can’t assemble virions –> prevent maturation of new viruses
NRTIs vs NNRTIs
- NRTIs–> COMPETITIVELY inhibit nucleotide binding to reverse transcriptase; must be phosphorylated by thymidine kinase to be active
- NNRTIs –> NON-COMPETITIVELY bind to reverse transcriptase (site diff from NRTI’s); don’t need to be phosphorylate to be active.
Antimicrobial drugs that act on 50S ribosomal subunit to block protein synthesis:
- Chloramphenicol
- Macrolides
- Streptogramins
- Clindamycin
- Linezolid
Antimicrobials that block protein synthesis AT 30S ribosomal subunit?
- Aminoglycosides
- Tetracyclines
Vancomycin and Bacitracin mechanism?
-block peptidoglycan synthesis
Fluoroquinolone mechanism?
blocks DNA topoisomerase
Penicillin mechanism of action:
- block cell wall synthesis by inhibiting peptidoglycan cross-linking
- bind PBPs (penicillin-binding proteins)
- activate autoclytic enzymes
Penicillinase-Resistant Penicillins:
- list them
- why are they resistant to penicillinase (Beta-lactamase)?
- clinical use?
- Methicillin, Nafcillin, Dicloxacillin
- have a bulkier R group, so are resistant to penicillinase
- used to treat S. aureus (but, not MRSA, b/c altered penicillin-binding protein target site)
Clinical use for Aminopenicillins (Ampicillin and Amoxicillin):
“HELPSS kill Enterococci”
- H. influenza
- E. coli
- Listeria
- Proteus
- Salmonella
- Shigella
- Enterococci
Tibarcillin, Carbenicillin, Piperacillin
=Carboxypenicillins = anti-Pseudomonals
“Take Care of Pseudomonas”
-used to treat Pseudomonas!
Beta-lactamase inhibitors: CAST
- Clavulonic Acid
- Sulbactam
- Tazobactam
*can add to penicillinase-sensitive antibiotics to prevent destruction by Beta-lactamases (ie to aminopenicillins)
Beta-lactamase inhibitors: CAST
- Clavulonic Acid
- Sulbactam
- Tazobactam
*can add to penicillinase-sensitive antibiotics to prevent destruction by Beta-lactamases (ie to aminopenicillins)
Antimicrobials that block cell wall synthesis by inhibiting peptidoglycan cross-linking:
- Penicillin
- Methicillin
- Ampicillin
- Piperacillin
- Cephalosporins
- Aztreonam
- Imipenem
Antimicrobials that block cell wall synthesis by inhibiting peptidoglycan cross-linking:
- Penicillin
- Methicillin
- Ampicillin
- Piperacillin
- Cephalosporins
- Aztreonam
- Imipenem
Antimicrobials that block peptidoglycan synthesis
- Vancomyci
- Bacitracin
Antimicrobials that block peptidoglycan synthesis
- Vancomyci
- Bacitracin
Antimicrobial that blocks nucleotide synthesis
- sulfonamides
- trimethoprim
***given together at TMP-SMX
Antimicrobial that blocks nucleotide synthesis
- sulfonamides
- trimethoprim
***given together at TMP-SMX
Antimicrobial that blocks DNA topoisomerases
Fluoroquinolones
- contraindicated in pregnant women and kids, b/c may damage cartilage
- only exception = can give fluoroquinolones to kids with CF
Antimicrobial that blocks DNA topoisomerases
Fluoroquinolones
- contraindicated in pregnant women and kids, b/c may damage cartilage
- only exception = can give fluoroquinolones to kids with CF
Antimicrobial that blocks mRNA synthesis?
Rifampin
Antimicrobial that blocks mRNA synthesis?
Rifampin
Antimicrobial that damages DNA?
Metronidazole
Antimicrobial that damages DNA?
Metronidazole
Antimicrobials that block protein synthesis at the 50S ribosomal subunit? 30S subunit?
“but AT 30, CCEL at 50”
- 30S subunit:
- Aminoglycosides
- Tetracyclines
- 50S subunit:
- Chloramphenicol
- Clindamycin
- Erythromycin (macrolides)
- Linezolid
Antimicrobials that block protein synthesis at the 50S ribosomal subunit? 30S subunit?
“but AT 30, CCEL at 50”
- 30S subunit:
- Aminoglycosides
- Tetracyclines
- 50S subunit:
- Chloramphenicol
- Clindamycin
- Erythromycin (macrolides)
- Linezolid
Are cephalosporins bacteriostatic or bactericidal?
Bactericidal
Mechanism of Cephalosporins?
They’re Beta-lactam drugs that inhibit bacterial cell wall synthesis (like Penicillin, by inhibiting peptidoglycan cross-linking), but less susceptible to penicillinases
–>Bactericidal
‘Which organisms are NOT covered by cephalosporins?
“LAME” organisms:
- Listeria
- Atypicals (ie Mycoplasma, Chlamydia)
- MRSA
- Enterococci
Chlamydia treatment:
Azithromycin or Doxycycline
N. meningitis treatment?
Ceftriaxone or Penicillin G
Treatment for Pseudomonas:
- Aminoglycoside + extended spectrum penicillin (ie an anti-pseudomonal: Ticarcillin, Carbenicillin, Piperacillin)
- -> can also treat with a 3rd gen cephalosporin (Ceftazidime) or 4th gen cephalosporin (Cefepime)
First generation cephalosporins coverage:
- gram (+) cocci
- “PEcK”
- Proteus
- E coli
- Klebsiella
Second generations cephalosporins coverage:
- gram (+) cocci
- “HEN PEcKS”
- H. influenza
- Enterobacter
- Neisseria
- Proteus
- E. coli
- Klebsiella
- Serratia
3rd generation cephalosporins coverage:
- serious gram (-) infections that are resistant to other Beta-lactams
- ceftriaxone: gonorrhea, meningitis, and late stage lyme disease (earlier, use doxycycline)
- ceftazidime: pseudomonas
4th generation cephalosporins coverage:
*increased activity against Pseudomonas and gram (+) organisms
Cefepime
4th generation cephalosporin; good for both gram (+) and gram (-) coverage
–>can be used to treat Pseudomonas
Ceftriaxone
3rd gen cephalosporin
-treats gonorrhea, meningitis, and late stage lyme disease
Ceftazidime
3rd gen cephalosporin
-can be used to treat Pseudomonas
Cefuroxime
2nd gen cephalosporin
Cefazolin
1st gen cephalosporin
cephalexin
1st gen cephalosporin
cefoxitin
2nd gen cephalosporin
cefaclor
2nd gen cephalosporin
cefotaxime
3rd gen cephaolosporin
3 Cephalosporin toxicities:
- may cross react with penicillins
- increased nephrotoxicity when given with Aminoglycosides
- Disulfiram-like reaction when take with ethanol
Mechanism and Clinical uses of Aztreonam:
*mechanism: inhibits cell wall synthesis by binding to PBP and inhibiting peptidoglycan cross-linking
- Clinical uses:
- ONLY gram (-) rods
- ->give to pts who are allergic to penicillins or pts who can’t tolerate aminoglycosides (b/c renal insuficiency; b/c side effect of aminoglycosides = nephrotoxicy, and aminoglycosides also treat gram (-) rods)
Imipinem:
broad-spectrum antibiotic
***Always given with Cilistatin (to prevent inactivation of Imipinem in renal tubules)
***only used for severe life-threatening conditions or after failure of other drugs, b/c has bad side effects (GI, CNS toxicities–> seizures)
Drugs that binds D-ala D-ala on bacterial cell wall precursors?
Vancomycin
Clinical use of vancomycin?
Gram (+) ONLY!
–>including: MRSA, C. diff (oral dose), enterococci
Toxicites of Vancomycin:
“NOT the Red Man!”
- Nephrotoxicity
- Ototoxicity
- Thrombophlebitis
- Red man syndrome = diffuse flushing