Micro 2 Flashcards
how to get food poisoning from S. aureus?
heat stable enterotoxin; NO FEVER
who’s more susceptible to SSS from S. aureus?
infants and children, acute onset of perioral erythema
how virulent is S. epidermitis compared to S. aureus?
less virulent and more indolent, does not ferment mannitol
does S. pneumoniae and viridans have lancefield ag?
nope
3 virulence factors in S. pneumoniae
polysacch capsule –> antiphag, igA protease, pneumolysin impairs mucociliary escalator
how to S. pneumoniae transmitted?
airborne and direct contact; mostly affects <2yo and >60yo; more in drier and colder months; viral infxns esp IAV inc S. pneumoniae shedding. nasopharyngeal carriage common –> lives in mucous layer, resists phag, attaches to epithelium
describe progression of S. pneumoniae
serotype dep, more likely in pts w/ COPD and IVDU
can S. pneumoniae cause bacteremia?
yes, common in pts w/ PNA but not w/ otitis media or sinusitis; endocarditis can occur secondary
how to dx S. pneumoniae?
urine pneumococcal ag rapid detection test, Quellung rxn for pneumococcal capsular serotyping
how to tx S. pneumoniae?
beta lactam and macrolide abx but resistance = increasing
what are the main virulence factors for Enterococcus?
adhere to tissues and form biofilms, high antimicrobial resistance to vancomycin
clinical dz of Enterococcus
UTI, peritonitis, wound infxns, bacteremia, endocarditis
how is B anthracis transmitted?
zoonotic, NOT person to person; spore enter body by skin contact, inhalation, ingestion of contaminate food, IV drug use
anthrax clinical pres
cutaneous by spore for vegetative form –> black eschar; GI by veg form –> nausea, bloody diarrhea, loss of appetite, fever, severe stomach pain; resp by spore form –> flu like sxs; bacteremia by any form –> fatal
how to dx B anthracis?
occupational and exposure hx (IVDU, farmer); can’t use sputum b/c airspace dz (broncho or alveolar PNA) = freq absent
how to tx B anthracis?
ab therapy w/ 2+ abx; 7-10d for cutaneous but other forms require 60d; monoclonal ab against protective ag in combo w/ abx; vaccine available and can be used w/ abx as postexposure prophylaxis
what dzs can B cereus cause?
gastroenteritis by 2 enterotoxins: heat stable (emetic) in unrefrigerated, contaminated, reheated rice; and heat liable (diarrheal) in contaminated meats and veggies. ocular infxns after penetrating eye w/ soil contaminated objects. device infxns, endocarditis in IVDU, PNA, bacteremia, meningitis
characteristics of B cereus?
opportunistic, environmental source like soil, common cx contaminant
what happened in 2001 for B anthracis?
bioterrorism in USPS envelopes
early vs late onset dz of neonatal listeriosis
acquired from placenta in utero –> granulomatous infantiseptica vs acquired at/soon after birth –> meningitis or meningoencephalitis w/ septicemia
pathogenesis of Listeria monocytogenes
enters into nonprof phagocyte –> internalized in a vacuole/phagosome –> secretes phospholipases and pore-forming toxin listeriolysin O –> released into cyto and uses actin polymerization to do actin rocket tail an jump to next cell –> enters another cell in double membraned vacuole
how to dx Listeria monocytogenes?
microscopy = nondiagnostic b/c bacterial titers = low –> selective media and cold enrichment (can grow in 4 degrees C) but tell lab you’re looking for Listeria monocytogenes and not confuse w/ Corynebacterium spp
how to tx Listeria monocytogenes?
combination therapy b/c bacteriostatic effects alone = not enough
morphology of Neisseria gonorrheae?
gram neg diplococci growing on chocolate agar, no capsule
How is Neisseria gonorrheae transmitted?
sex; only occurs in humans; can be passed down to neonates at birth –> purulent conjunctivitis; 2nd most common STD behind chlamydia
pathogenesis of Neisseria gonorrheae
LOS not LPS, intracellular infxn of neu; pili and opa proteins aid in attachment and intracellular killing, porin proteins aid in intracellular survival, Rmp proteins and IgA protease dec ab mediated killing, ag variation of pilin proteins evade immune system
gonorrhea in men vs women
urethritis, purulent d/c vs cervicitis, vaginal d/c, PID; disseminated infxns (gonococcemia) w/ septicemia and skin or joint infxns; Fitz Hugh Curtis syndrome (perihepatitis), pharyngitis & anorectal gonorrhea from oral/anal sex
how to dx Neisseria gonorrheae vs chlamydia?
rapid nucleic acid amplification test (NAAT); they don’t assess abx resistance so you still need to cx vs NAAT or ag detect
how to tx Neisseria gonorrheae? how to prevent?
challenging b/c resistant to beta lactams, tetracyclines, fluroquinolones; treat all partners. barrier protection during sex
major pathogens of Klebsiella vs Enterobacter vs Serratia
K. pneumoniae/oxytoca/granulomatis vs E. cloacae/aerogenes/sakazakii vs S. marcescens
transmission of Klebsiella
hypervirulent strains in Taiwan and SE Asia –> septicemia; granuloma inguinale or donovanosis by K. granulomatis; opportunistic and endogenous, noscomial pathogen
drug resistant for Kleb vs Enterobacter vs Serratia
resistant to all beta lactams d/t extend spectrum beta lactamases, carbapenem-resistant vs carbapenem-resistant vs nothing stated but bioterrorism potential
how is yersinia pestis transmitted?
zoonotic: bite from infected wild rodents or infected flea vector; person to person by resp droplets; direct contact w/ amplifying host
pathogenesis of Yersinia pestis
fimbriae and capsular proteins adhere to cells –> YOPs dec phag killing –> plasminogen activator (pla) protease degrade C3b and C5a
types of dz of Yersinia pestis
bubonic –> high fever and painful bubo; pneumonic –> primary or secondary to bubonic, progressive bloody sputum, primary or secondary to bubonic; septicemic –> abd pain, DIC, gangrene, organ failure; pestis minor –> more benign bubonic plague
how to dx Yersinia pestis?
cx, stain, serology, PCR
systemic infx of Yersinia entercolitica
contaminated blood products; erythema nodosum (T4HS), reactive arthritis (T3HS)
Pseudomonas can cause hosp-acquired infxns in pts w/?
opportunistic transmission; neutropenia, immunocompromised (HIV, CF), IVDU
Is Pseudomonas a lactose fermenter? does it have mucoid?
no. plus/minus
is H pylori acid sensitive?
yes, grows in acidic gastric pH
epidemiology of H pylori
establish life-long colonization, 70-100% of pts w/ gastritis = infected w/ H pylori
does Salmonella disseminate?
rarely disseminate systemically but ppl can be long term asx carrier
what strains cause salmonellosis?
S. enteriditis and S. typhimurium
Haemophilus ducreyi vs aegyptious vs parainfluenzae
causes extremely pain chancroid STD vs causes acute purulent conjunctivitis/pink eye; complication = Brazilian Purpuric Fever –> acute septicemia vs rare opportunistic pathogen causing endocarditis, bacteremia, brain abscesses
Bartonella quintana vs B. bacilliformis
Trench fever vs Carrion dz (oroya fever –> acute hemolytic bacteremia, verruga peruana/Peruvian warts –> look like bacillary angiomatosis); in Andes of Peru, Colombia, Ecuador
major pathogens of Bartonella
B. henselae, quitana, bacilliformis
morphology of Bartonella
extremely fastidious (grows in cx in 2-6wks), facultative intracellular in RBCs and endothelial cells
transmission of Bartonella
insect vectors or direct contact w/ infected animal; henselae = cats, fleas, quitana = lice, bacilliformis = sandflies
how to dx Bartonella?
serology
morphology of moraxella
aerobic diplococci
dz of moraxella
otitis media, acute and chronic sinusitis, lower resp tract infxn like COPD
dx vs tx of moraxella
butyrate test, doesn’t [O] carbs vs make beta lactamases b/c beta lactam resistant
pathogen and infxn of citrobacter
C. freundii; opportunistic and nosocomial infxnx
how long tick must attach to give lyme dz?
24h
how to tx Borreliosis/lyme dz?
early tx to prevent late stages; long term abx therapy for PTLDS = ineffective
how to dx coxiella/Q fever?
paired serum to test for C. burnetti ab
morphology or myco/ureaplasma
smallest, free living bacteria, very pleomorphic, no cell wall, cell membrane has sterols
pathogenesis of mycoplasma
P1 adhesion binds to glycoproteins at base of cilia –> lytic enzymes and H2O2 destroy cilia –> superag activity releases cytok storm
pathogenesis of nocardia
secrete catalase and oxidase –> avoid phag; cord factor –> prevent phagolysosome fusion; prevent acidification of phagosome
dx of clostridium perfringens
purplish, gas bubbles, MOUSY odor, severe pain; 2x zone hemolysis
tx of clostridium perfringens
surgical debridement + abx + supportive care
transmission vs risk factors of C diff
fecal oral vs abx exposure, GI surgery, long hosp stay, underlying illness, immunocompromised, age
how to tx non-sporeforming anaerobic bacteria
metronidazole –> break DNA helix –> no protein synthesis
epidemiology of peptostreptococcus
Normal flora w/ an/aerobic bacteria –> synergistic; 2nd most freq recovered anaerobes and ¼ of anaerobic isolates
morphology of Gardnerella vaginalis
gram variable, nonmotile, coccobaccilli, fac anaerobe
morphology of lactobacilli
gram pos aerotolerant bacilli, normal flora in oropharynx
dz of lactobacilli
very rare. transient bacteremia post childbirth or GU procedure; endocarditis after dental work or dmged heart valves; opportunistic septicemia in immunocompromised
dx of lactobacilli
3 pos cx 24h part
morphology of cutibacterium acnes
gram pos aerotolerant bacilli; catalase pos and make propionic acid
dz of cutibacterium acnes
cutaneous = acne vulgaris, comedones (not related dot hygiene)
ocular = blepharitis and endophthalmitis post surgery
orthopedic = infected joint prosthetics esp shoulder
ex of gram neg anaerobic rods
bacteroides (B. fragilis = most virulent), porphyromonas, prevotella, fusobacterium; common symbionts for digestion and mucosal immunity (NOT skin)
pathogenesis of gram neg anaerobic rods
fimbriae induce proinflamm responses; antiphag capsule, short chain FA inhibits phag and intracellular kills; proteases dec ab
pathogenesis of Bacteriodes fragilis
heat labile zinc metalloprotease toxin –> actin rearrangement –> Cl- secretion and fluid loss
dz of anaerobic gram neg rods
general: abscesses w/ low O2
resp: hx of apiration
brain: h/o chronic sinus/ear infxns and polymicrobial
intraabd: B. fragilis
gyn: prevotella
skin & soft tissue: bite, not part of nml skin microbiome
bacteremia: B. fragilis
GI: B fragilis producing enterotoxin –> colorectal ca
how to dx anaerobic gram neg rods
stains show mixed pleomorphic bacteria, aerobic cx show no growth; Bacteroides Bile Esculin and Laked Kanamycin Vancomycin bi-plate (BBE/LKV)
transmission vs dz vs dx of pasteurella
Zoonotic –> dog/cat bite/scratch vs pasteurellosis: lymphadenopathy and cellulitis early in infxn –> osteomyelitis vs mousy odor
HAECK dz
subacute endocarditis d/t pre-existing heart dz vs clumps/aggregates; adolescent periodontitis; occurs w/ actinomyces vs from human bite wounds –> bleach like odor; occurs w/ aggregatibacter –> from nail biting and periodontal dz vs eh vs from human bites and resp droplets; osteomyelitis/septic arthritis in children 6mo-3y
HAECK pathogens vs epidemiology
haemophilus, aggregatibacter, eikenella corrodens, cardiobacterium hominis, kingella kingae vs in oropharynx
how much bacteria does coxiella need to infect?
1-10 organisms –> potential bioterrorism agent
what causes TSS vs TSS like?
staph aureus vs group A/C of strep pyogenes
how to tx bordetella?
macrolides
how does Stx work?
Stx B binds Gb3 glyclolipid and transfers A subunit to 60S –> Stx A depurinates ribosome –> stop protein synthesis
pos screening test for syphilis = confirmed by?
FTPPA, TPPA
