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59 Cards in this Set
- Front
- Back
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facultative anaerobic rods include
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family enterobacteriaceae
other facultative anaerobic rods - vibrio - aeromones - haemophilus - pasteurella |
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family Enterobacteriaceae includes
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Escherichia
Salmonella Shigella Klebsiella Enterobacter Proteus Yersinia others: Serriatia, morganella, hafnia, citrobacter, edwardsiella, providencia, pantoea |
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gram negative aerobic rods include
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Pseudomonas
Stenotrophomonas Burkholderia Acinetobacter Legionella Bordetella Brucella Bartonella Francisella |
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gram negative microaerophilic rods include
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campylobacter
helicobacter |
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enterobacteriaceae morphology & antigens
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typical gram negative rods
antigens: - cellwall: O Ag - Flagella : H Ag - capsule: K, Vi Ag |
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Enterobacteriaceae habitat
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normalGI microbiota: humans/animals
environmental: usually due to fecal contamination |
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enterobactreiaceae physiology
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facultative anaerobes
ferment glucose oxidase negative (differentitaor b/w pseudomones) nitrate reductionto nitrite (check with dipstick) |
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differentiation of gram negative rods
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glucose fermentation; nitrate reduction
- : Pseudomonas, others ; oxidase positive results in Pseudomonas aeruginosa + : Salmonella, shigella, E. coli, others those that were +, now test for lactose fermentation - : salmonella & shigella + : e. coli, others shigella is H2S negative salmonella is H2S positive E. coli is indole + others are indole negative |
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E. coli general characteristics
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normal colonic microbiota
- Coliforms: usually environmental microbiology lactose positive (pink on MacConkey Agar); indole + (red ring in tube) opportunistic infections |
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E coli opportunistic infections include
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UTI
GI Neonatal meingitis Septicemia/sepsis |
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E. coli UTI signs & symptoms
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cystitis: pain (dysuria), frequency of urination, urgency
- bladder infection Pyelonephritis: fever, chills, flank pain, nausea, vomiting |
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E. coli UTI epidemiology
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community acquired (females associated with sex)
nosocomial |
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E coli UTI lab diagnosis
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dip stick: leukocyte, esterase, nitrite
urine culture - quantitate if necessary - >100,000 cfu/mL ; in asymptomatic pt is diagnostic; esp in pregnancy; but elderly should not betreated if asymptomatic |
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E coli UTI therapy
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acute & uncomplicated
Trimethoprim-sulfamethoxazole ; co-trimozazole - alpha fluoroquinolon; over prescriptoin results in resistance |
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types of E. coli that cause gastroenteritis (diarrhea)
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Enterotoxigenic E. coli : ETEC: traveler's diarrhea/infant diarrhea
Enterohemorrhagic E. coli : EHEC or shiga-toxin producing E. coli (STEC) more serious Enteropathogenic E. coli :EPEC Enteroinvasive E. coli : EIEC ENteroaggressive E. coli: EAEC Enteroadherent E. coli :EAEC |
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Enterotoxigenic E. coli signs & symptoms
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watery diarrhea/cramping
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Enterotoxigenic E. coli Virulence
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plasmid-encoded pili: colonization/adherance
plasmid-encoded enterotoxins - heat labile toxin (LT) easily destroyed by heat == AB toxin == ADP-ribosylation ; stimulates adenylate cyclase; increases cAMP & excretion of water & electrolytes - Heat stable toxin (ST) == stimulates guanylate cyclase ; decreases NA & Cl & water absorption |
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ETEC epidemiology
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travelers/infants in emerging countries
food/water |
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EHEC
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plasmid-encoded pili: adhesion
phage encoded toxins: lysogenic - shiga-like toxin: STEC, Verotxoin == AB toxin == inhibition of protein synthesis == quorum sensing regulated type III secretion |
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EHEC disease
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hemorrhagic colitis
- bloody diarrhea - hemolytic uremic syndrome : HUS |
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Hemolytic uremic syndrome triad
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renal failure
hemolytic anemia thrombocytopenia: decrease platelets, increase vascular blood clots |
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EHEC epidemiology
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food borne, direct contact
- undercooked beef, raw veggies, unpasteurized juices/milk, animal contact person to person - serotype 0157:H7 - if not salmonella, assume EHEC |
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Enteropathogenic E. coli
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watery diarrhea
infants |
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Enteroinvasive E. coli
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indistinguishable from shigellosis (shigella)
children |
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Lab ID of E. coli gastroenteritis
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culture
biochemical/serological/molecular |
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therapy for E. coli gastroenteritis
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re-hydration + electroylates (all forms)
antimotility agents (pepto bismol) - all but bloody diarrhea - not children antimicrobials - try to avoid - not for EHEC or other shiga toxin producing - may shorten ETEC course == fluroquinolone; azithromycin; rifaximin |
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prevention of E. coli gastroenteritis
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sanitation
food handling/preparation keep food separate ; >160 degrees ; |
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meningitis caused by E. coli
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epidemiology: neonatal
S/S: Resp distress, fever, irritability, failure to eat, lethargy, etc. specimens: CSF & blood lab ID: gram stain ; culture (MacConkey) therapy: 3rd generation cephalosporins (ceftriaxone) |
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E. coli can cause these other infections
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intraabdominal
pneumonia soft tissue nosocomial septicemia other |
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Shigella characteristics
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gram negative
facultative anaerobic rod non motile ; hint SYK (shigella, yersinia, klebsiella) non lactose fermenter no H2S |
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Shigella species
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technically biogropus of E. coli
S. dysenteriae (least common) S. sonnei (most common in US) S. flexneri S. boydii |
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Shigella disease & epidemiology
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Bacillary dysentery : shigellosis, enterocolitis
strict human pathogen - fecal-oral |
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Shigella virulence
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low infectious dose
mucosal cell & mac invasion & growth Shiga toxins: lysogenic - T3SS |
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Shigella S/S
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similar to EHEC
Diarrhea : abrupt onset with fever & cramps - water to bloody - no bacteremia |
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Shigella lab diagnosis
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PMNs, blood, & mucus in stool
stool culture: MacConkey - biochemical; molecular |
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Shigella therapy & prevention
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self limiting
- fluid/electrolyte replacement - antimicrobials : trimethoprim-sulfamethoxazole; ampicillin ; fluroquinolone; others prevention: sanitation |
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salmonella characteristics
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gram negative
facultative anaerobic rod motile non lactose fermenters produce H2S (black preciptate on medium with iron salts) |
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Salmonella taxonomy CDC & WHO new classification
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2 species
S enterica: 7 subspecies ; > 2600 serovars - most human pathogens in subspecies enterica == S. enterica subspecies enterica serovar Enteritidis == S. enterica subspecies enterica serovar Typhi S. bongori: cold blooded animals |
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salmonella classic taxonomy classification
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hundreds of species
S. enterica: others include: S. typhimurium, S. enteritidis, >2600 additional - gastroenteritis : food poisoning - localized; non systemic S. typhi & S. paratyphi - typhoid fever: enteric fevers - human to huma - bacteremic; systemic |
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Salmonella diseases
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2 Gastrointestinalforms: infection initiated in GI tract
gastroenteritis: enterocolitis; S. enterica & subspecies ; S. typhimurium, S. enteritidis enteric fever: typhoid fever & similar infections typhoid fever: S. typhi |
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2 GI forms of diseases from salmonella
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localized gastroenteritis
- food poisoning - animal hosts disseminated siease - enteric ; typhoid fever |
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Gastroenteritis from salmonella epidemiology
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animal reservoir
food borne/contact with animals - poultry/eggs, beef, pork, water, vegetables - reptiles, chickens, cats, dogs, etc |
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salmonella gastroenteritis pathogenesis
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invasion of intestinal mucosa
>100,000 infectious dose localized, no bacteremia; limited to lamina propria/adjacent mesetners LN's |
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Salmonella gastroenteritis S/S & lab diagnosis
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short incubation; 12-72 hours
Diarrhea, fever, abdominal cramps self limiting : 5-7 days lab dx: stoolculture - lactose neg, H2S + |
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salmonella gastroenteritis therapy & prevention
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fluids/electrolytes
antimicrobials: usually none; self limiting - 3rd generation cephalosporin ; a fluoroquinoloone prevention: sanitiation; thoroughly cooked foods |
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salmonella enteric fever
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S. typhi: typhoid fever
S. paratyphi: Yersinia enterocolitica |
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Salmonella epidemiology & pathogenesis of typhoid fever
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humans only
fecal oral (food borne) infect M cells in peyer pathces of SI - macs- bacteremia- liver, spleen, gallbladder, kidneys, bone marrow, heart - bacteremia - other organs, tissues (intestinal tract) systemic spread; peyers patches can be re-infected |
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Salmonella typhoid fever S/S & lab dx
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long incubation period : 1-2 wks
malaise, anorexia, myalgia, arthralgia, cough, sore throat, headache, mental confusion, slow pulse (relative brady), rose spots on chest fever usually begins 1 wk post exposure blood culture early, stools or urine late; bone marrow molecular probe/PCR serology: widal test |
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typhoid fever by salmonella therapy & prevention
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a fluroquinolone or ceftriaxone
antimicrobial decreases mortality from 20% to near 0 prevention - sanitation - vaccination - carriers |
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Klebsiella pneumoniae characteristics
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gram neg
facultative anaerobic rod urease + non motile large capsule mucoid colonies normal flora in resp/GI tracts |
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klebsiella pneumoniae diseases
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opportunistic infections: lobar pneumonia & bronchopneumonia (alcholics, nursing home pts, other debilitated; acute pneumonia (sudden onset, chills, fever, difficulty in breathing, cough, & blood stained sputum)
UTI bacteremia: top 5 cause of nosocomial burn, wound, etc |
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Klebsiella pneumonia epidemiology, virulence factors & S/S
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normal microbiota
antiphagocytic capsule pneumonia: bloody sputum ("currant" jelly) typical UTI, may be stones (calculi) |
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clinical signs of bacterial pneumonia
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shaking chills
fever chest pain cough SOB |
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Klebsiella pneumoniae lab dx & therapy
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culture, urease test, others
Antimicrobials (3rd generation cephalosporin) - multiresistance common == emergence of carbapenemase-producing strains 1. imipenem, meropenem, others 2. spreading to other Enterobacteriaceae (esp E. coli) |
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Enterobacter
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nosocomial UTI's ; opportunistic
immunocompromised (bacteremia) therap (imipenem or meropenem; MDR common) |
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Proteus
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general characteristics: Swarming, urease +
nosocomial UTI: urinary calculi therapy: ampicillin or 3rd generation cephalosporin (species dependent) |
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what gram negative bacteria produces swarming
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Proteus
hyper flagelation stage swarm & stop de differentiation into dividing non swarming vegetative cells Rings produced after several cycles |
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Yersinia types
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Y. enterocolitica
Y. pestis: Plague (black death) |
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Y. enterocolitica
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Enterocolitis: esp pediatric
- toxin similar to ST of E. coli - fever, ab pain, diarrhea, may be confused with appendicities enteric fever (trimethoprim-sulfamethoxazole) - not as serious as typhoid |
