USMLE - Microbiology
Terms
undefined, object
copy deck
- virulence factor of staph aureus - binds Fc-IgG, inhibiting complement fixation and phagocytosis
- protein A
- superantigen that binds to MHC II and TCR, resulting in polyclonal T cell activation
- TSST - (staph aureus)
- what makes coagulase?
- staph aureus
- antibody to what enhances host defenses against strep pyogenes?
- M protein
- group A beta-hemolytic strep?
- strep pyogenes
- what detects recent strep pyogenes infections?
- ASO titer
- associated with rusty sputum, sepsis in sickle cell, and splenectomy?
- strep pneumo
- most common cause of meningitis, otitis, pneumonia, sinusitis?
- strep pneumo
- what gives immunity to strep pneumo?
- IgG antibodies to surface acidic polysaccharide
- causes pneumonia, meningitis, and sepsis mainly in babies
- group B strep (agalactiae) - beta hemolytic, bacitracin resistant
- what is Lancefield grouping based on?
- differences in the C carbohydrate on the bacterial cell wall
- what can grow in 6.5% NaCl
- enterococci
- enterococci can cause what?
- UTI, subacute endocarditis, biliary tract infections
- bacteria related to colon cancer?
- strep bovis
- type of strep viridans that can cause subacute bacterial endocarditis?
- strep sanguis
- what does C. perfringens produce?
- alpha toxin
- gram-positive rods with metachromatic granules?
- corynebacterium diphtheriae
- woolsorter's disease?
- bacillus anthracis
- inhalation of anthrax spores?
- flulike symptoms that rapidly progress to fever, pulmonary hemorrhage, and shock
- gram-positive anaerobe that causes oral/facial abscesses that may drain through sinus tracks in skin
- actinomyces
- gram positive, weakly-acid fast aerobe that causes pulmonary infection in immunocomprimised patients
- nocardia asteroides
- sulfur granules
- actinomyces
- gram-positive rods forming long branching filaments resembling fungi
- actinomyces & nocardia
- most invasive disease of H. flu is caused by what capsular type?
- B
- treatment for H. flu meningitis?
- ceftriaxone
- treatment for neisseria gonorrhea?
- ceftriaxone - also z pack or doxycycline because 50% will also be infected with chlamydia
- why don't you want to culture if pt. has epiglottitis?
- manipulation cause laryngeal spasm
- members of enterobacter family (7)
- e. coli, salmonella, shigella, klebsiella, enterobacter, serratia, proteus
- what antigen is related to the virulence of enterobacter?
- K antigen
- all of these ferment glucose and are oxidase negative
- enterobacter
- these bacteria grow pink colonies on MacConkey's agar
- klebsiella, e. coli, enterobacter (KEE), citrobacter
- salmonella or shigella: motile and can disseminate hematogenously?
- salmonella
- salmonella or shigella: which is more virulent?
- shigella
- salmonella or shigella: symptoms may be prolonged with antibiotic treatments
- salmonella
- salmonella or shigella: animal reservoir
- salmonella
- this is usually transmitted from pet feces, contaminated milk, or pork; outbreaks common in daycare centers
- yersinia enterocolitica
- this can mimic Crohn's or appendicitis & can disseminate to produce lymphadenitis
- yersinia enterocolitica
- arthritis can develop with yersinia infection in patients with what?
- HLA-B27
- vibrio parahaemolyticus and v. vulnificus
- contaminated seafood
- reheated rice
- B. cereus
- meats, mayonase, custard
- s. aureus
- reheated meat dishes
- c. perfringens
- undercooked meat
- e. coli 0157:H7
- poultry, meat, eggs
- salmonella
- bloody diarrhea; comma or S-shaped organisms
- campylobacter
- is campylobacter motile?
- yes
- e. coli producing shiga-like toxin; can cause HUS
- enterohemorrhagic
- day-care outbreaks, pseudoappendicitis
- yersinia
- protazoan causing bloody diarrhea
- entamoeba histolytica
- protaozoa causing watery diarrhea
- giardia, cryptosporidium (in immunocompromised)
- treatment for legionella?
- erythromycin
- UTI - urine with alkaline pH
- proteus - very motile - able to break down urea
- pneumonia in CF
- pseudomonas
- wound and burn infections
- pseudomonas
- treatment for pseudomonas?
- amnoglycoside plus extended-spectrum penicillin (piperacillin, ticarcillin)
- aerobic gram-negative rod; oxidase positive, non-lactose fermenting; pyocyanin pigment
- pseudomonas
- hot tub folliculitis
- pseudomonas
- pneumonia, sepsis, UTI, drug use and diabetic osteomyelitis
- pseudomonas
- cellulitis from animal bite, cats, dogs
- pasteurella
- dairy products, contact with animals
- brucella
- ghon complex
- TB granulomas (Ghon focus) with lobar and perihilar LN involvement; reflects primary infection or exposure
- mycobacterium scrofulaceum
- cervical lymphadenitis in kids
- mycobacterium kansasii
- pulmonary TB-like symptoms
- acid-fast bacillus that likes cold temperatures and cannot be grown in vitro
- mycobacterium leprae
- reservoir for m. leprae in U.S.?
- armadillos
- what does m. leprae infect?
- skin and superficial nerves
- treatment for leprosy?
- long-term oral dapsone - toxicity is hemolysis and methemoglobinemia
- which type of Hanson's diseaseiis worse?
- lepromatous worse than tuberculoid
- the chlamydial petidoglycan wall is unusual in that it lacks what?
- muramic acid
- treatment for chlamydia?
- erythromycin or tetracycline
- cytoplasmic inclusions seen on Giemsa or fluorescent antibody-stained smear
- chlamydia
- infection of liver capsule with RUQ pain; associated with chlamydial or gonococcal infection
- Fitz-Hugh-Curtis syndrome
- how do the reticulate bodies of chlamydia replicate?
- binary fission
- types A, B, and C of chlamydia
- Africa/Blindness/Chronic infection
- types D-K of chlamydia
- urethritis/PID, ectopic pregnancy, neonatal pneumonia or conjunctivitis
- types L1, L2, and L3 of chlamydia
- lymphogranuloma venereum (acute lymphadenitis - positive Frei test)
- treatment for neonate after passage through chlamydia-infected birth canal?
- erythromycin eye drops
- most common STD in U.S.?
- chlamydia
- only spirochete that can be visualized using analine dyes (Wright's or Giemsa stan) in light microscopy
- borrelia
- shepherd's crook-shaped spirochete
- leptospira
- Wal's disease
- fatal from of leptospira infection - jaundice, bleeding, renal failure, skeletal muscle necrosis
- treatment for Borrelia recurrentis?
- doxycycline, erythromycin
- treatment for Lyme disease?
- doxycycline
- what causes yaws?
- tremonema pertenue - tropical infection that is not an STD, although VDRL test is positive
- what are important reservoirs for ixodes? what is required for tick life cycle?
- mice; deer
- signs of tertiary syphilis?
- broad-based ataxia; positive Romberg; Charcot joints; stroke without hypertension
- congenital syphilis?
- saber shins, saddle nose, deafness
- primary syphilis?
- painless chancre
- secondary syphilis?
- disseminated isease with constitutional symptoms, maculopapular rash (palms and soles), condylomata lata
- VDRL positive, FTA positive?
- active infection
- VDRL positive, FTA negative?
- probably false positive
- VDRL negative, FTA positive?
- successfully treated
- VDRL false positives?
- viruses (mono, hep), drugs, rhematic fever, RA, SLE, leprosy
- Weil-Felix reaction?
- classic test that uses cross-linking proteus antigens to confirm diagnosis of rickettsia
- strep associated with pharyngitis, cellulitis, impetigo, scarlet fever, TSS, rheumatic fever, glomerulonephritis?
- strep pyogenes (group A beta hemolytic)
- characteristics of rheumatic fever?
- subcutaneous nodules, erythema marginatum, chorea, carditis
- tumbling motility, menigitis in newborns, unpasteurized milk
- listeria monocytogenes
- virulence factor of staph aureus?
- protein A
- what does c. difficile produce?
- a cytotoxin, an exotoxin that kills enterocytes, causing pseudomembranous colitis
- what encodes the exotoxin of corynebacterium diphtheriae?
- beta-prophage
- vesicular papules covered y black eschar
- bacillus anthracis
- what part of gram-negative bugs inhibits entry of penicillin and vancomycin?
- the outer membrane layer
- this vaccine contains type B capsular polysaccharide conjugated to diphtheria toxoid or other protein
- h. flu
- flagellar antigen of enterobacter?
- H antigen
- somatic antigen of enterobacter?
- O antigen (polysaccharide of endotoxin)
- viruses causing watery diarrhea?
- rotavirus, adenovirus, norwalk virus
- pertussis toxin permanently disables what?
- Gi
- cholera toxin permanently activates what?
- Gs
- how does pertussis toxin promote lymphocytosis?
- by inhibiting chemokine receptors
- treatment of choice for most rickettsial infections?
- tetracycline
- classic triad of rickettsiae?
- headache, fever, rash (vasculitis)
- rickettsiae are obligate intracellular parasites and need what?
- CoA and NAD
- all rickettsiae except what are transmitted by an arthropod vector and cause headache, fever, and rash?
- coxiella
- why is coxiella an atypical rickettsia?
- because it is transmitted by aerosol and causes pneumonia
- what causes rocky mountain spotted fever? to where is it endemic?
- rickettsia rickettsii; endemic to east coast
- vector for rocky mountain spotted fever?
- tick; rickettsia rickettsii
- vector for endemic typhus?
- fleas; rickettsia typhi
- vector for epidemic typhus?
- human body louse; rickettsia prowazekii
- what causes Q fever?
- coxiella burnetii
- rickettsial disease with no rash, no vector, negative Wiel-Felix, and casative organism can survive outside for a long time
- coxiella burnetii
- what does the Weil-Felix reaction assay for?
- antirickettsial antibodies, which cross-react with proteus antigen
- what is the only bacterial membrane containing cholesterol?
- mycoplasma pneumoniae
- growth on Eaton's agar?
- mycoplasma pneumoniae
- normal flora dominant in nose
- staph aureus
- normal flora dominant in skin
- staph epidermidis
- normal flora dominant in oropharynx
- strep viridans
- normal flora dominant in dental plaque
- strep mutans
- normal flora dominant in colon
- bacteriodes fragilis > e. coli
- normal flora dominant in vagina
- lactobacillus, colonized by e. coli and group B strep
- common causes of pneumonia in kids (6 wks. - 18 yrs)
- viruses (RSV), mycoplasma, c.pneumonia, s.pneumo
- common causes of pneumonia in adults (18-40)
- mycoplasma, c.pneumo, s. pneumo
- common causes of pneumonia in adults (40-65)
- s. pneumo, h. flu, anarobes, viruses, mycoplasma
- common causes of pneumonia in elderly
- s. pneumo, viruses, anaerobes, h.flu, g-rods
- common causes of pneumonia in nosocomial
- staph, gram-negative rods
- common causes of pneumonia in immunocomprimised
- staph, gram-negative rods, fungi, viruses, PCP (HIV)
- common causes of pneumonia in aspiration
- anaerobes
- common causes of pneumonia in alcoholic/IV drug user
- strep pneumo, klebsiella, staph
- common causes of pneumonia in postviral
- staph, h. flu
- common causes of pneumonia in neonate
- group B strep, e. coli
- common causes of atypical pneumonia
- mycoplasma, legionella, chlamydia
- causes of meningitis in newborn (0-6 mos)
- GBS, e.coli, listeria
- causes of meningitis in children (6 mos - 6 yrs)
- s. pneumo, n.meningitidis, h.flu B, enterovirus
- causes of meningitis in 6-60 year olds
- n.meningitidis, enterovirus, s.pneumo, hsv
- causes of meningitis in elderly (over 60)
- s.pneumo, g-rods, listeria
- causes of meningitis in HIV
- cryptococcus, CMV, toxoplasmosis (brain abscess), JC virus (PML)
- CSF findings in bacterial meningitis
- increased pressure, neutrophils, protein - decreased sugar
- CSF findings in fungal/TB meningitis
- increased pressure, lymphocytes, protein - decreased sugar
- CSF findings in viral meningitis
- n/+pressure, + lymphocytes, normal protein and sugar
- cause of osteomyelitis in most people
- staph aureus
- cause of osteomyelitis in sexually active
- neisseria gonorrhoeae (rare), septic arthritis more common
- cause of osteomyelitis in diabetics and drug addicts
- pseudomonas
- cause of osteomyelitis in sickle cell
- salmonella
- cause of osteomyelitis in prosthetic replacement
- staph aureus and staph epidermidis
- cause of vertebral osteomyelitis
- TB (Pott's disease)
- UTI in ambulatory patients
- e. coli (50-80%), klebsiella (8-10%)
- second most common cause of UTI in young ambulatory women
- staph saprophyticus
- cause of UTI in hospital?
- e. coli, proteus, klebsiella, serratia, pseudomonas
- UTI - colonies show metallic sheen on EMB agar
- e. coli
- UTI - large mucoid capsule and viscous colonies
- klebsiella
- UTI - swarming on agar (motility); produces urease
- proteus
- vaginitis, strawberry-colored mucosa
- trichomonas vaginalis
- noninflammatory, malodorous discharge; positive whiff test; clue cells
- gardnerella vaginalis
- risk factor: newborn nursery
- CMV, RSV
- risk factor: urinary catheterization
- e. coli, proteus
- risk factor: respiratory therapy equipment
- pseudomonas aeruginosa
- risk factor: work in renal dialysis unit
- HBV
- risk factor: hyperalimentation
- candida albicans
- risk factor: water aerosols
- legionella
- infections dangerous in pregnancy
- ToRCHeS: toxo, rubella, CMV, HSV, HIV, syphillis
- traumatic open wound
- c. perfringens
- surgical wound
- staph aureus
- sepsis/meningitis in newborn
- group B strep
- neutrophils in CSF?
- bacterial meningitis
- normal protein and sugar in meningitis?
- viral
- teichoic acid is unique to what type of organisms?
- gram-positive
- endotoxin/LPS (outer membrane) is unique to what type of organisms?
- gram-negative
- what do teichoic acid and lipid A induce?
- TNF and IL-1
- space between the cytoplasmic membrane in gram-negative bacteria
- periplasm - contains many hydrolytic enzymes, including beta lactamases
- this mediates adherence to surfaces, especially foreign surfaces, e.g. indwelling catheters
- glycocalyx - made of polysaccharide
- this contains a variety of genes for antibiotic resistance, enzymes, and toxins
- plasmid - made of DNA
- what is the only gram-positive with endotoxin?
- listeria
- what is exotoxin made of?
- polypeptide
- what is endotoxin made of?
- lipopolysaccharide
- typical diseases with exotoxin?
- tetanus, botulism, diphtheria
- tpical diseases with endotoxin?
- meningococcemia, sepsis by gram-negative rods
- gram-negative cocci?
- neisseria
- these have a gram-negative cell wall but are too small to be seen with light microscope
- spirochetes - must be visualized with darkfield microscope
- no cell wall; neither gram-positive or gram-negative
- mycoplasma
- lipopolysaccharide found in cell wall of gram-negative bacteria
- endotoxin - heat stable
- this bug inactivates elongation factor (EF-2), causes pharyngitis and pseudomembrane in throat
- corynebacterium diphtheriae
- ADP ribosylation of G protein stimulates adenylyl cyclase, increasing pumping of Cl- and H20 into gut
- cholera
- what does e. coli heat-labile toxin stimulate?
- adenylate cyclase
- what does e. coli heat-stable toxin stimulate?
- guanylate cyclase
- name the 6 classic gram-positives
- strep, staph, bacillius, clostridium, corneybacterium, listeria
- what does bordatella pertussis stimulate?
- adenylate cyclase; also inhibits chemokine receptor
- double zone of hemolysis on blood agar?
- C. perfringens
- what does C. tetani block the release of?
- inhibitory NT glycine
- what does C. botulinum block the release of?
- acetylcholine
- what does shiga toxin do?
- cleaves host cell rRNA; also enhances cytokine release, causing HUS
- what type of bugs are rickettsia and chlamydia?
- intracellular parasites
- neisseria meningitidis ferments what?
- maltose and glucose
- neisseria gonorrhea ferments what?
- glucose
- what produces a blue-green pigment?
- pseudomonas
- what produces a red pigmetn?
- serratia maracescens
- IgA proteases allow what organisms to colonize mucosal surfaces?
- strep pneumo, neisseria meningitidis, neisseria gonorrhoeae, h. flu
- silver stain?
- fungi, PCP, legionella
- india ink?
- cryptococcus neofromans
- Ziehl-Neelsen stain?
- acid-fast baceria
- PAS stain?
- stains glycogen, mucopolysaccharides; used to diagnose Whipple's disease
- Giemsa's stain?
- borrelia, Plasmodium, trypanosomes, chlamydia
- congo red?
- amyloid; apple-green birefringence in polarized light (because of beta-pleated sheets)
- chocolate agar with factors V and X?
- H. influenzae
- Thayer-Martin (VCN) agar?
- N. gonorrhoeae
- Bordet-Gengou (potato) agar?
- B. pertussis
- tellurite plate, Loffler's medium, blood agar?
- C. diphtheriae
- Lowenstein-Jensen agar?
- M. tuberculosis
- pink colonies on MacConkey's agar?
- lactose-fermenting enterics - Klebsiella, e. coli, enterobacter (fast); citrobacer, serratia (slow)
- charcoal yeast agar buffered with increased iron and cysteine?
- Legionella
- Sabouraud's agar?
- fungi
- obligate aerobes (4)
- Nagging Pests Must Breathe: nocardia, pseudomonas, mycobacterium, TB, bacillius
- obligate anaerobes (3)
- clostridium, bacteriodes, actinomyces - lack catylase and/or superoxide dismutase, and thus are susceptible to oxidative damage; generally foul smelling, difficult to culture, and produce gas in tissue (CO2 and H2)
- obligate intracellular bugs (2)
- rickettsia, chlamydia (stay inside when it's Really Cold)
- facultative intracellular (8)
- Some Nasty Bugs May Live FacultativeLY:
- salmonella, neisseria, brucella, mycobacterium, listeria, francisella, legionella, yersinia
- encapsulated bugs (4)
- strep pneumo, H. flu, neisseria meningitidis, klebsiella - positive quellung reaction
- bacillus anthracis, c. perfringens, and c. tetani form what?
- spores (gram positive soil bugs)
- alpha hemolytic bacteria?
- s.pneumo(cat-, optS), s.viridans (cat-, optR)
- beta hemolytic bacteria?
- s. aureus (cat+, coag+), GAS (cat-, bacS), GBS (cat-,bacR), listeria
- how do you differentiate strep pyogenes form strep agalactiae?
- strep agalactiae (bacitracin S), strep agalactiae (bacitracin R)
- DNA transferred from 1 bacterium to another
- conjugation
- nature of DNA transferred in conjugation
- chromosomal or plasmid
- DNA transferred by a virus from 1 cell to another
- transduction
- nature of DNA transferred in transduction
- any gene in generalized transduction; only certain genes in specialized transduction
- purified DNA taken up by a cell
- transformation (any DNA)
- most capsules are made out of polysaccharide except bacillus anthracis, which contains what?
- d-glutamate
- chemical composition of spore?
- keratin-like coat; dipicolinic acid - provides resistance to heat, dehydration, and chemicals
- what is a pilus made out of?
- glycoprotein
- location of exotoxin genes?
- plasmid or bacteriophage
- location of endotoxin genes?
- bacterial chromosome
- which is antigenic - exotoxin or endotoxin?
- exotoxin
- both of these bugs activate EF-2
- corynebacterium, pseudomonas (exotoxin A)
- how do you distinguish staph epidermidis from staph saprophyticus
- s. epidermidis is novabiacin S, s. saprophyticus is novabiacin R
- another name for group A beta hemolytic strep?
- strep pyogenes
- another name for group B beta hemolytic strep?
- strep agalactiae
- which is bile soluble - strep pneumo or strep viridans?
- strep pneumo