Microbio Clinical bacteriology Flashcards
gram pos, branching filament, anaerobe, not acid fast
actinomyces
gram pos, branching filaments, aerobe, acid fast
nocardia
gram pos cocci in clusters, catalase pos
staph
gram pos cocci in chains, catalase neg
strep
gram pos cocci in clusters, catalase pos, coag pos
staph aureus
gram pos cocci in chains, cat pos, coag neg
staph epidermis and staph saprophyticus
gram pos cocci in chains, cat neg, alpha hemolytic
strep pneumo, viridans strep (strep mutans)
gram pos cocci in chains, cat negative, beta hemolytic
group A strep (strep pyogenes), group B strep (strep agalactiae)
gram pos cocci in clusters, catalase neg, gamma hemolytic (no hemolysis)
group D strep (enterococcus and non-enterococcus)
distinguishing between the two kinds of gram pos cocci, cat pos, coag neg staph
novobiocin sensitive is staph epi; novobiocin resistant is staph saprophyticus
distinguishing between gram pos cocci, clusters, cat neg, alpha hemolytic
strep pneumo is optochin sens and viridans strep is optochin resistant
distinguish between gram pos cocci, clusters, cat neg, beta hemolytic
group A strep is bacitracin sens; group B strep is bacitracin resistant
beta hemolytic bacteria
staph aureus (cat pos and coag pos); strep pyogenes (group A strep), strep agalactiae (GBS), listeria
TSST
superantigen produced by staph aureus that binds to MHC II and T cell receptor, resulting in polyclonal T cell activation;
staph epidermis association
prosthetic devices and IV atheters by producing biofilm. coag neg. novobiocin sensitive
staph sapro
second most common cause of uncomplicated UTI in young women (first is E. coli). Coag neg. novobiocin resistant
strep pneumo
most common cause of meningitis, OM, pneumonia, sinusitis
lancet shaped, gram pos diplococci. Encapsulated
strep pneumo
viridans group strep
alpha hemolytic (like strep pneumo), but optochin resistant; normal flora of the oropharynx (cavities); types are strep mutans (dental caries) and strep sanguinis (subacute endocarditis at damaged heart valves)
strep pyogenes (group A strep)
pharyngitis, cellulitis, scarlet fever, rheumatic fever, glomerulonephritis; M protein; ASO titer detect recent Strep pyogenes infxn
JONES major criteria for acute rheumatic fever
joints (polyartritis), carditis, nodules (subcutaneous), erythema marginatum, syndenham chorea
scarlet fever rash
scarlet rash with sandpaper-like texture, strawberry tongue, circumoral pallor, subsequent desquamation
strep agalactiae
Group B strep; bacitracin resistant; beta hemolytic; colonizes vagina; causes infxn mainly in babies;
Group D strep
there are enterococcal and non-enterococcal group D strep
strep bovis
a type of group D strep that colonizes the gut; assoc with colon cancer; can cause bacteremia and subacute endocarditis
Corynebacterium ditheriae
causes diptheria via exotoxin encoded by beta-prophage; exotoxin works through EF-; sx include pseudomembraneous pharyngitis with lymphadenopathy, myocarditis and arrhythmias; toxoid vaccine prevents diptheria
gram pos rods
clostridium (anaerobe), corynebacterium, listeria, bacillis (aerobe)
bacterial spores
bacillus anthracis, bacillus cereus, clostridium botulinum, clostridium difficile, clostridium perfringens, clostridium tetani, coxiella burnetii (Q fever)
clostridium tetani
producses tetanospasmin (cleaves SNARE proteins)
clostridium botulinum
toxin inhibits Ach release; in adults, ingestion of preformed toxin; in babies, ingestion of spores in honey causes disease; tx with antitoxin
clostridium perfringens
produces alpha toxin that can cause myonecrosis (gas gangrene) and hemolysis
clostridium difficile toxins
Toxin A (enterotoxin) binds to brush border of gut. Toxin B (cytotoxin) causes cytoskeletal disruption leading to pseudomembraneous colitis and diarrhea. Often 2/2 clinda or ampicillin. Dx by detection of one or both toxins in the stool by PCR
anthrax
caused by b. anthracis, a gram pos spore forming rod that produces anthrax toxin. This is the only bacterium with a polypeptide capsule (contains D-glutamate)
cutaneous anthrax
painless papule surrounded by vesicles which eventually ulcerates with a black eschar; uncommonly progresses to bacteremia and death
pulmonary anthrax
inhalation of spores leads to flu like sx that rapidly progress to fever, pulmonary hemorrhage, mediastinis, and shock
b. cereus
food poisoning; spores sens to cooking; keeping rice warm leads to germination of spores and enterotoxin formation; emetic type (rice and pasta) and diarrheal type (watery, nonbloody)
listeria monocytogenes
acultative intracellular microbe; acquired by ingestion of unpasteurized dairy products and cold deli meats or during pregnancy or birth; forms rocket tails that allow intracellular and trans-cellular movement; tumbling motility”; only gram pos organism to produce endotoxin
what kinds of diseases can gram pos rod listeria monocytogenes cause?
amnionitis, stpticemia, and spont abortion in pregnant women; granulomatosis infantiseptica; neonatal meningitis; mild gastroenteritis in healty people; treat gastroenteritis supportively use ampicillin in infants, elderly and immunocomp
acid fast gram pos branching filaments
nocardia (actinomyces is not acid fast)
actinomyces
gram pos branching filaments, not acid fast, normal oral flora, causes oral/facila abscesses, treat with penicillin
nocardia
gram pos branching filaments, acid fast, found in the soil, causes pulm infextion in immunocompromised and cutaneous infextions after trauma in immunocompetent; treat with sulfonamides
features of primary TB
ghon complex in hilar nodes and ghon focus in lower to mid zones of lung
secondary TB
either due to reinfection in a partially immune hypersesntized host or reactivation; fibrocaseous cavitary lesion, usually in upper lobes of lung
Extrapulmonary TB
CNS (parenchymal TB or meningitis); vertebral body (Pott disease); lymphadenitis; renal; GI; adrenals
intergeron gamma release assay for TB
has fewer false positives from BCG vaccination than the PPD
mycobacteria
m. tuberculosis, m. avium intracellulare (AIDS, proph with azithro with CD4 less than 50); m. scrofulaceum (cervical lymphadenitis in kids); m. marinum (hand infection in aquarium handlers); all mycobacteria are acid fast
“cord factor” in virulent strains of mycobacteria
inhibits macrophage maturation and induces release of TNF-a
leprosy (Hansen disease)
caused by mycobacterium leprae (acid fast bacillus) that likes cool temps (infects skin and superficial nerves); glove and stocking loss fo sensation; resevoir in US is armadillos
Hansen disease has two form
lepromatous presents diffusely over the skin of lion-like facires and is communicable; characterized by low cell-mediated immun with a humorial TH2 response; tuberculoid form is limited to a few hypoesthetic hairless skin plaques; characterized by high cell-mediated immunity with largely TH1 type immune response
treatment of Hansen disease (leprosy)
dapsone and rifampin for tuberculoid form; clofazimine is added for lepromatous form
gram neg diplococci
neiserria meningitidis and neisseria gonorrhea
gram neg diplococci maltose fermenter
n. meningitidis
gram neg diplococci maltose nonfermenter
n. gonorhea
gram neg “coccoid” rods
Haemophilus influenza, pastuerella, brucella, bordatella pertusis
gram neg comma shaped
campylobacter jejuni, v. cholera, h. pylori
gram neg rods lactose nonfermenter
pseudomonas, salmonella, proteus, yersinia, shigella
gam neg rods lactose fermenter
klebsiella, e coli, enterobacter, cirtobacter, serratia, others
gram neg rods lactose nonfermenter oxidase pos
pseudomonas
gram neg rods lactose nonfermenter oxidase neg
salmonella, proteus, yersinia, shigella
gram neg rods lactose fermenter, fast fermenters
klebsiella, e coli, enterobacter
gram neg rods lactose fermenter slow fermenter
citrobacter, serratia, others
lactose fermenting bacteria
fermentation of lactose leads to pink colonies on MacConkey agar. Examples include citrobacter, klebsiella, e coli, enterobacter, and serratia
neisseria gonococci
no polysaccharide capsule (unlike meningococci), no maltose fermentation (unlike mening), no vaccine, treat with ceftriaxone
neisseria meningitidis
polysaccharide capsule, maltose fermentation, vaccine, trasmitted via resp and oral secretions, causes meningococcemia and meningitis and waterhouse-friderichsen syndrome; prophylaxis with rifampin, cipro, or ceftriaxone in close contacts; treat with ceftriaxone or penicillin G
h. influenza
smal gram neg coccobacillary rod; aerosol transmission; mucosal infections; produces IgA protease; culture on chocolate agar; treat mucosal infxn with amox-clav and meningitis with ceftriaxone.
HIB vaccine
contains type B capsular polysaccharide conjugated to diptheria toxoid or other protein; given between 2 and 18 mos of age
legionella
gram neg rod; use silver stain (bc gram stains poorly); grow on charcoal yeast extract and cx with irone an dcysteine; detect antigen in urine; labs may show hyponatremia; aerosol transmission from environental water source habitat, no person to person transmission; treat with macrolide or quinolone
Legionairre’s disease
caused by legionella (obvi); severe pneumonia, often unilateral and lobar, fever, Gi, and CNS sx
Pontiac fever
mild flu-like syndrom caused by legionella
pseudomonas
gram neg rod, lactose fermenter; produces blue-green pigment; aerobic; grape-like odor; endotoxin and exotoxin; common n burn victms;chronic PNA in CF patients due to biofilm; hot tub folliculitis
ecthyma gangrenosum
rapidly progressive, necrotic cutaneous lesion caused by pseudomonas bacteremia; typically seen in immunocomp patients
E coli virulence factors
fimbrae- cystitis and pyelo; K capsule- pneumonia, neonatal meningitis; LPS endotoxin- septic shock
EIEC
invades intestinal mucosa and causes necrosis and inflamm; causes invasive dysentery
ETEC
heat-labile and heat-stabile enterotoxin; no inflamm or invasion; causes traveler’s diarrhea (water)
EPEC
no toxin produced; adhere to apical surface, flattens villi, prevents absorption; diarrhea, usually in kids (P=pediatrics)
EHEC
shiga toxin producing; O157:H7 is most common serotype in the US; shiga-like toxin causes HUS (triad of anemia, thrombocytopenia, and acute renal failure); mechanical hemolysis, platelet consumption; dysentary; does not ferment sorbtol (distinguishes EHEC from other E coli)
Klebsiella
intestinal flora that causes lobar pneumonia in alcoholics nad diabetics when aspirated; dark red “currant jelly” sputum (blood/mucus); also cause of nosocomial UTIs
campylobacter jejuni
comma or S-shaped gram neg; major cause of bloody diarrhea, esp in kids; fecal-oral transmission through person to person contact or via ingestion of poultry, meat, unpast milk. Contact with infected animals is another RF. Common antecdent to GB and reactive arthritis
salmonella and shigella
both are gram neg bacilli that are non-lactose fermenters and oxidase neg
salmonella typi in particular
resevoid is humans, can dissem hematogenously, H2S production, flagella, endotoxin, large inoculum required for infxn bc organism inactivated by gastric acids; abx prolong duration of fecal excretion; immune response is monocytes; constipation followed by diarrhea; oral vaccine available; causes typhoid fever (tx with ceftriazone or quinolone); carrier state with GB colonization
salomonella species not typhi)
resevoir is humans and animals; can dissem hematogenously, H2S producton, flagella, endotoxin, large inoculum required; abx prolongs duration; PMNs in dissem disease; bloody diarrhea; no vaccine; sources are poultry, eggs, pets and turtles; gastroenteritis is usually caused by non-typhoidal salmonella
shigella
humans only; cell to cell transmission (no hematogenous spread); no flagella, endotoxin and enterotoxin; low inoculum required; abx shortens duration; primarily PMN infiltration; bloody diarrhea; no vaccine
vibrio cholera
rice water diarrrhea via enterotoxin that permanently activates cAMP; comma shaped; oxidase pos; endemic in dveloping counties; prompt oral rehydration necessary
yersinia enterocolitica
usually transmitted from pet feces, contaminated milk, or pork; causes acute diarrhea or pseudoappendicitis (right lower abdominal pain due to mesenteric adenitis and/or terminal ileitis)
h. pylori
curved gram neg rod that is catalase, oxidase, and urease pos; gastirits and peptic ulcers (esp duodenal); FR for peptic ulcer, gastric adenocarcinoma, and MALT lymphoma. Creates alkaline environment
spirochetes examples
borrelia, leptospira, and treponeme; borrelia is big
leptospira interrogans
type of spirochete; found in water contaminated with animal urine; causes leptospirosis (flu-like illness, jaundice, photophobia with conjunctival suffusion; prevalent among surfers and in tropics (Hawaii)
Weill disease
severe form of leptospirosis with jaundice and azotemia from liver and kidney dysfunction, fever, heomrhage, and anemia
Lyme disease
caused by borrelia burgdorferi, which is transmitted by the Ixodes tick (also vactor for anaplasma and babesia) but natural resevoir is the mouse; treat with doxy or ceftrizone; facial nerve palsy may be seen, cardiac block, erythema chronicum migrans
primary syphilis
painLESS chnacre; dx by using darkfield microscopy to visualize treponemes from the chancre; VDRL pos in 80%
secondary syphilis
constitutional sx, maculopapular rash (incl palms and soles); condylomata lata
congenital syphilis
facial abnormalities like rhagades (linear scars at angle of mouth), snuffles (nasal discharge), saddle nose, notched (Hutchinson) teeth, mulerry molars, and short maxilla; saber shins; CN 8 deafness
how to prevent congenital syphilis
treat mother early in pregnancy, as placental transmission typically occurs after the first trimester
VDRL false positives
test is sensitive but not specific; false pos are Viral infection (mono, hepatitis), Drugs, Rheumatic fever, Lupus and leprosy
Jarish-Herxheimer reaction
flu-like syndrome after abx are started; due to killed bacteria (usually spirochetes) releasing endotoxins
anasplasma species of bacteria
carried by the ixodes ticks (on deer and mice)
bartonella
cat scratch disease, bacillary angiomatosis
borrelia recurrentis
relapsing fever; carried by the louse
brucella
brucellosis/indolent fever; get from unpastuerized dairy
campylobacter
bloody diarrhea; get from puppies and livestock (fecal-oral, ingestion of undercooked meat)
chlamydophila psittaci
psittacosis; get from parrots and other birds
coxiella burnetii
Q fever; get from aerosols of cattle/sheep amniotic fluid
ehrlichia chaffensis
get from ambyloma (Lone star tick)
francisella tularensis
causes tularemia; get from ticks, rabbits, deer fly
leptospira species
get from animal urine
mycobacterium leprae
causes leprosy; get from humans with lepromatous leprosy and also from armadillos (rare)
pastuerella multicoda
causes cellulitis or osteomyelitis; get from animal bites, dog or cats
rickettsia prowazekii
causes epidemic typhus; carried by the louse
rickettsia rickettsii
rocky mountain spotted fever; get from Dermacentor (dog tick)
rickettsia typhi
epidemic typhus; get from fleas
salmonella
causes diarrhea, vomitting, fever, abd cramps; get from reptiles and poultry
yersinia pestis
caused the plauq; get from fleas (rats and prarie dogs are resevoirs)
gardnerella vaginalis
pleomorphic gram variable rod; involved in bacterial vaginosis; gray vaginal dc with a fishy smell; assoc with sexual activity but not sexually transmitted; clue cells; treat with metronidazole or clindamycin; amine whiff test gives fishy odor
rocky mountain spotted fever
rickettsia rickettsii; vector is tick; disease occurs primarily in the south atlantic states (esp North carolina); rash starts at wrists and ankles and spread to trunk, palms, and soles
palms and soles rash
RMSF, coxsackie virus (hand, foot, mouth disease), and secondary syphilis
typhus
rickettsia typhi, rickettsia prowazekii; rash starts centrally and spreads peripherally, sparing the palms and soles
ehrlichiosis
vector is tick; monocytes with morulae (berry-like inclusions) in cytoplasm
anaplasmosis
vector is tick; granulocytes with morulae in cytoplasm
Q fever
coxiella burnetii; no arthropod vector; spores inhaled as aerosoles from cattle/sheep amniotic fluid; presents as PNA; most common cause of culture negative endocarditis; Q fever has no rash or vector and its causative organism can survive outside in its endospore form
chlamydiae
obligate intracellular organism; cause mucosal infxns in 2 forms (elementary body enters the cell and transforms into reticulate body, which replicates and reforms into elementary body)
types of chlamydia
trachomatis is the nl one I think of (PID, urethritis, reactive arthritis, conjunctivitis); pneumoniae and psittaci cause atypical pneumonia, transmitted by aerosol, has an avian resevoir
chlamydia trachomatis serotypes
A,B, and C (“africa, blindness, chronic infection”); Types D-K (urethritis/PID, neonatal pneumonia with eosinophilia, neonatal conjunctivitis); Types L1,L2, L3 cause lymphogranuloma venereum (small, painless ulcers on genitals and painful swollen inguinal lymph nodes that ulcerate, treat with doxy)
treatment for chlamydia (in general)
azithromycin (favored bc one time treatment) or doxy
mycoplasma pneumonia
classic cause of atypical (“walking”) PNA; xray looks worse than patient; treat with macrolides, doxy or quinolones (penicillins ineffective because mycoplasma has no cell wall); common in people less than 30 yo, military recruits and prisons; bacterial membrane contains sterols for stablity; pleomorphic and no cell wall so not seen on gram stain
