Clinical bacteriology Flashcards

Question

Anthrax

Answer 1

Bacillus anthracis - spore-forming rod, makes anthrax toxin - Only bacteria w/ polypeptide capsule (D-glutamate) Cutaneous anthrax - boil lesions, painless + become necrotis [rarely progresses] Pulmonary anthrax - Inhalation of spores, flu-like --> fever --> pulm hemorrhage --> mediastinitis --> shock *Woolsorter's disease - inhaled from contaminated wool

Answer 2

Food poisoning, spores survive cooked rice - Emetic type: * Cereulide = preformed toxin, get w/ rice or pasta, n/v in 1-5 hrs - Diarrheal type: * Watery, non-bloody diarrhea + GI pain, 8-18hr *Reheated rice syndrome*

Answer 3

Facilitative INTRACELLULAR microbe - Rocket-tails (actin polym) allow them to move in cytoplasm to cell membrane (avoid Ab); tumbling motility * *Make LPS (only gram + to do this!) * *Narrow B-hemolytic, replicate at refrig temp (refrig food) - Ingesting unpasteurized dairy/deli meat, transplacental or vaginal at birth - Baby: amnionitis, septicemia, spont abortion, granulomatosis, meningitis - Immunocompromised - meningitis - Healthy - mild GI disease Tx - GI = self-limited - Ampicillin - empiric meningitis tx (babies, immunocompromised, elderly)

Answer 4

Both gram positive - Actinomyces - not acid fast, in normal oral flora, get oral/facial abscesses with draining yellow "sulfur granules" * A. israelii = actinomyces, yellow sand in israel - Nocardia - acid fast, in soil, get pulm infections in immunocompromised * Tx = sulfonamides

Answer 5

All are acid-fast organisms - Mycobacterium TB = TB - M. kansasii - pulm, TB-like sx (water contaminant of municipal H2O system, not nature) - M. avium-intracellulare (disseminated non-TB in AIDS) --> ppx = azithromycin

Answer 6

Primary - Ghon focus (mid lung) - Heal by fibrosis - immunity/hypersensitivity --> tuberculin + - Progressive lung disease (in HIV, malnutrition) = rare - Severe bacteremia = miliary TB = death - Preallergic lymphatic/hematogenous dissemination --> dormant tubercle bacilli in organs --> reactivation later Secondary TB - reinfected, fibrous caseating granulomas (upper lobes) - See w/ reactivation of TB of lunds - Extrapulm TB - CNS (tuberculoma or meningitis), vertebral body (Pott)

Answer 7

- PPD pos if current infection, past exposure or BCG vaccine - PPD neg if no infection, anergic (steroid, malnutrition, immunocompromised), or sarcoid - TH1-cell mediated delayed hypersensitivity response * IFN-gamma release assay has fewer false + (esp BCG vaccine)

Answer 8

``` TB = caseating granulomas Sarcoidosis = non-caseating granulomas ```

Answer 9

Hansen disease; from mycobacterium leprae - Acid-fast bacillus - Likes cool temperatures, infects skin/superficial nerves ("glove + stocking" sensation loss) * Can't grow in vitro - Reservoir = US armadillos Lepromatous form - diffusely on skin, leonine facies (lion-like), communicable - Low cell-mediated immunity (humoral TH2 response) * Tx = dapsone, rifampin, clofazimine 2-5 yrs Tuberculoid form - hairless plaques - High cell-mediated immunity (largely TH1 response) * Tx = dapsone + rifampin x6mo

Answer 10

- Diplococci - Coccoid rods - Rods - lactose fermenter vs. lactose non-fermenter - Oxidase +, comma shaped

Answer 11

Gram negatives resistant to penicillin G/vanc! - May be susceptible to derivatives (ampicillin, amoxicillin) * Outer membrane layer inhibits entry of penicillin and vancomycin

Answer 12

Gram negative bacteria: - Neisseria meningitidis - Neisseria gonorrhoeae * Both make IgA protease

Answer 13

Diplococci, gram negative bacteria, STD - No polysaccharide capsule - No maltose fermentation (ferment glucose) - No vaccine bc rapid pilus proteins - Sx: gonorrhea, septic arthritis, neonatal conjunctiv, PID/Fitz-Hugh-Curtis syndrome - Tx = ceftriaxone (+ azithro/doxy for chlamydia co-infection) *Opaque exudate, intracellular organisms (in neutrophils)*

Answer 14

Diplococcia, gram negative bacteria - Polysaccharide capsule - Maltose and glucose fermentation - Vaccine (except type B) - Have in respiratory/oral secretions --> pili adhere to oral mucosa - Sx: meningococcemia (purpuric lesions, shock, death), meningitis, Waterhouse-fridrichsen syndrome (adrenal destroyed) - Tx: ceftriaxone or penicillin G

Answer 15

Gram negative bacteria - H. influenzae - Pasteurella - Brucella - Bordetella pertussis

Answer 16

Gram negative coccoid rod, aerosol transmission - H. influenza B (type B) = CAPSULE, most invasive - Makes IgA protease - Cx on chocolate agar w/ factors V and X for growth * Can grow with E. coli - provides factor V - Sx: haEMOPhilus - epiglottitis (cherry red), meningitis, otitis media, pneumonia - Tx mucosal - amoxicillin, clavulanate - Tx meningitis - ceftriaxone; rifampin ppx for contacts

Answer 17

Type B capsular polysaccharide conjugated to protein | - Give age 2-18 mos

Answer 18

Lactose fermenter vs. nonfermenters Lactose fermenters: - Fast fermenters: Klebsiella, E. coli, Enterobacter - Slow fermenters: Citrobacter, Serratia * Grows on "macConKEE'S agar" Lactose non-fermenters - Oxidase + = pseudomonas - Oxidase neg = shigella, salmonella, yersinia, proteus

Answer 19

``` Gram negative, lactose fast-fermenter Virulence factors: - Fimbriae - cystitis/pyelonephritis - K capsule - pneumonia, neonatal meningitis - LPS endotoxin - septic shock ``` EIEC - Invasive; dysentery ETEC - Traveler's diarrhea (watery) EPEC - Pediatric diarrhea EHEC - Hemolytic-uremic syndrome

Answer 20

Microbe invades intestinal mucosa --> necrosis and inflammation - Presents similarly to shigella

Answer 21

Heat-labile (HL) and heat-stable (HS) enterotoxins - No inflammation/invasion --> TOXIN mediated *Travel's diarrhea from enteroToxins

Answer 22

No toxin made - bacteria adheres to apical surface, flattens villi, prevents absorption in intestine *Diarrhea usually Pediatric

Answer 23

Dysentery --> toxin alone causes necrosis/inflam O157:H7 most common - Shiga-like toxin, inactivate 60S subunit of ribosome, causes Hemolytic-uremic syndrome (anemia, thrombocytopenia, acute renal failure) *aka STEC (shiga toxin-producing E. coli) - Microthromi form on epithelium damaged by toxin --> mechanical hemolysis (schistocytes), decr renal blood flow **Microthrombi also consume plts = thrombocytopenia (thrombi + thrombocytopenia) *Doesn't ferment sorbitol or make glucuronidase (all other E. coli do)

Answer 24

Gram negative, lactose fast-fermenter - Normal intestinal flora --> lobar-pneumonia in alcoholics/DM when aspirated - "Red currant jelly" sputum (=intusussception of mouth!) - Nosocomial UTIs too 4A's: aspiration pneumonia, abscess in lung/liver, Alcoholics, diAbetics

Answer 25

Gram negative, lactose non-fermenter, oxidase neg - No flagella, cell-to-cell transmission (no hematogenous) * Humans/primates = only animal reservoir - Shiga toxin inactivates 60S - invades intestinal mucosa (binds mucosal M cells) --> PMN response; often causes bloody diarrhea - Doesn't make hydrogen sulfide - Abx - shorten fecal excretion of organism

Answer 26

Gram negative, lactose non-fermenter, oxidase neg - Flagella ("salmon swim"), can disseminate hematogenously * Animal reservoirs - Invades intestinal mucosa --> monocytic response; can cause bloody diarrhea - Makes hydrogen sulfide - Abx - prolong fecal excretion of organism

Answer 27

Typhoid fever, only in humans - Rose spots on abd, fever, HA, diarrhea - Can stay in gallbladder = carrier state

Answer 28

Gram negative, lactose non-fermenter, oxidase neg - From pet feces (puppies), contaminated milk or pork - Sx - mesenteric adenitis, mimic Crohn's/appendicitis

Answer 29

Aerobic gram negative, lactose non-fermenter, oxidase positive - Makes pyocyanin --> blue-green pigment on cx, smells like grapes - Comes from contaminated water - Makes endotoxin (fever, shock) and endotoxin A (inactivates EF-2) - Sx: wound/burns + *PSEUDOmonas = pneumonia (CF, biofilm), sepsis, external otitis, UTI, Drug use, Diabetic Osteomyelitis, hot-tub folliculitis (papulopustular rash) - Tx: amingoglycoside + extended-spectrum penicillin Ecthyma gangrenosum - necrotic cutaneous lesion, immunocompromised pts, from pseudomonas * Aeruginosa = Aerobic; water connection w/ blue-green pigment * contaminated water, burn victims, CF (chronic pneumo)

Answer 30

- Campylobacter jejuni - grow at 42C - Vibrio cholerae - grow in alkaline environment - Heliobacter pylori - produce urease

Answer 31

Gram negative bacteria, comma/S shaped, oxidase +, grows at 42C (campylobacter by hot camp fire) - Fecal-oral (meats/unpasteurized milk, puppies) * 500 org for innoculation - Sx: blood diarrhea (esp in kids) * *Common cause of Guillain-Barre syndrome + reactive arthritis

Answer 32

Gram negative bacteria, comma/S shaped, oxidase +, grows in alkaline media - Enterotoxin permanently activates Gs --> cAMP - Profuse rice-water diarrhea via enterotoxin - Endemic to dx countries; need prompt ORS

Answer 33

Gram negative bacteria, curve shaped, oxidase, catalase +; produces urease - Risks: gastritis, PUD (esp duodenal), lymphoma, adenocarcinoma, SMOKING - Creates alkaline environment - Tx = triple therapy (PPI, clarithromycin, amox/metronidazole) *Dx - urea breath test (urea producing) or fecal antigen test

Answer 34

Gram negative rod, need silver stain - Grow on charcoal yeast w/ iron/cysteine - Aerosol transmission from water source (A/C, hot tub) --> NO PERSON-TO-PERSON - Tx: macrolide (eryth/clarith/azithro) or quinolone Legionnaire's disease = severe pneumonia, fever, GI/CNS sxs **Think Legionella when pneumonia and GI!!!** "Legionnaire - silver helmet, sitting w/ charcoal and iron dagger

Answer 35

Spiral-shaped bacteria with axial filaments BLT - Borrelia (Big) <-- dark field microscopy

Answer 36

Spirochete; Lyme disease = borrelia burgdorferi - Transmitted by tick Ixodes; reservoir = mice Disease progr: 1) Early = flu-like, erythema chromicum migrans (Bull's eye/target) 2) AV block, Bell's palsy 3) Chronic asym jt arthritis, encephalopathy - Tx: doxycycline or ceftriaxone (penicillin-type) *FAKE = facial n palsy, arthritis, kardiac block, erythema migrans*

Answer 37

Spirochete, found in water contaminated w/ animal urine - Sx - flu-like, jaundice, photophobia conjunctival suffusion (red, no exudate) - See in surfers in the tropics (Hawaii) Weil disease - iscterohemorrhagic leptospirosis = severe form w/ jaundice + azotemia (liver/kidney disfxn)

Answer 38

Spirochete, causes syphilis - Primary - painless chancre - Secondary - disseminated, rash on palms/soles - Tertiary - gummas, neurosphyilis (tabes dorsalis), Argyll robertson pupil - Congenital *VDRL/RPR = non-specific; FTA-ABS confirm

Answer 39

Localized - painless chancre | - Use dark-field microscopy to see treponema from chancre

Answer 40

Disseminated - constitutional sx, maculopapular rash on hands/soles, condylomata lata - Confirm with dark-field microsc - Eventually get latent syphillis (w/o sxs)

Answer 41

Gummas (chronic granulomas), aortitis (vasa vasorum destruction, weakened aorta w/ AA-not dissection), neurosyphilis (tabes dorsalis), argyll robertson pupil - Sx - broad-based ataxia, +Romberg, charcot join, stroke w/o HTN - Dx - spinal fluid w/ VDRL/RPR (neurosyph)

Answer 42

Saber shins, saddle nose, CN VIII deafness, Hutchinson teeth, mulberry molars - Tx mom early (transmission after T1)

Answer 43

Constricts with accomodation, but does not react to lifht - Tertiary syphilis "Prostitute pupil" - accomodates but doesn't react

Answer 44

Nonspecific, react with beef cardiolipin | - VDRL - viruses (mono, hepatitis), drugs, rheumatic fever, lupus/leprosy

Answer 45

Flu-like syndrome after start abx bc of killed bacteria releasing pyrogens

Answer 46

Pleomorphic gram-variable rod - vaginosis - Gray vaginal discharge, fishy smell - Associated with sexual activity (not STD) - Overgrowth of certain anaerobic bacteria in vagina * Microscopy - clue (vagina epithelial) cells covered in bacteria - Tx: metronidazole or clinda "I have no CLUE why I smell FISH in the VAGINA GARDEN!"

Answer 47

Tx for all = DOXY! Rash common: "Rickettsi on wRists, Typhus on Trunk" - Rocky Mountain spotty fever - Typhus Rash rare: - Ehrlichiosis - Anaplasmosis - Q fever

Answer 48

Rickettsia rickettsii --> tick vector - South atlantic (NC) - Obligate intracellular organisms - need CoA/NAD+ (can't make ATP) Sx triad: HA, fever, rash - Rash starts on wrists/ankles --> spreads to trunk, palms, soles * Coxsackievirus A (hand/foot/mouth), RMSF, 2 syphillis --> all rashes w/ palms+soles

Answer 49

Endemic (fleas) --> R. typhi Epidemic (human body louse) - R prowazekii - Rash starts centrally, moves out; spares palms/soles

Answer 50

Ehrlichia --> tick vector | - Monocyte w/ morulae (berry-like inclusion) in cytoplasm

Answer 51

Anasplasma --> tick vector | - Granulocyte with morulae in cytoplasm

Answer 52

Coxiella burnetii - no arthropod vector - Tick feces/cattle placenta release spores, inhale as aerosols - Sx = pneumonia Q fever = Queer bc no arthropod vector, no rash --> survives outside endospore - Related to rickettsia genus (not part)

Answer 53

Obligate intracellular (cloak = chlamys) organisms - Elementary body - infectious, enters via endocytosis --> becomes reticulate body - Reticulate body - replicates in cell via fusion --> reorganize into elementary body * Cycle - Dx - cytoplasmic inclusions on Giemsa/fluorescent ab-stained smear - Tx - azithromycin or doxy

Answer 54

- C. trachomatis - C. pneumoniae + C. psittaci - atypical pneumonia (aerosol = atypical transmission) * Psittaci = avian reservoir

Answer 55

- Sx - reactive arthritis (Reiter syndr), follicular conjunctivis, nongonococcal urethritis, PID Type A,B,C - Africa, blindness, chronic infection Types D-K - urethritis/PID, ectopic pregn, neonatal pneumonia (staccato cough), conjunctivitis * D-K = everything else Type L1,L2,L3 - lymphogranuloma verenum = small, painless ulcers on genitals --> swollen painful inguinal LNs that ulcerates (buboes)

Answer 56

No cell wall (sterols for stability), not seen on gram stain Atypical "walking" pneumonia, pts <30yo - Insidious onset, HA, nonprod cough, patchy/diffuse interstitial infiltrates - XR looks worse than pt - Cold agglutinins (IgM) - can agglutinate or lyse RBCs * Often in military recruits/prisons* Tx - macrolide, doxy, fluoroquinolone. Penicillin doesnt work bc no cell wall!