Use LEFT and RIGHT arrow keys to navigate between flashcards;
Use UP and DOWN arrow keys to flip the card;
H to show hint;
A reads text to speech;
87 Cards in this Set
- Front
- Back
|
3 key characteristics of enterobacteriaceae |
Oxidase neg Ferment glucose Reduce nitrate to nitrite |
|
|
2 categories of enterobacteriaceae |
Opportunistic pathogens Overt or primary pathogens |
|
|
Opportunistic enterobacteriaceae |
Part of normal flora but may cause disease outside of their normal habitat |
|
|
Overt or primary enterobacteriaceae |
Not normal flora of GI tract Recovery in culture is always sig If present always causing disease |
|
|
Coliform |
Gram neg rod shape Non spore forming Ferment lactose Produce acid or gas |
|
|
Lipopolysaccharide endotoxin |
Virulence factor In cell wall causes fever, leukopenia, activate clotting, shock |
|
|
Endotoxin |
Released due to normal bacterial life cycle process or when destroyed |
|
|
Antigens that can be used to serologically group entero organisms |
O antigen H antigen K antigen |
|
|
O antigen |
Somatic antigen on cell wall that is heat stable |
|
|
H antigen |
Flagellar antigen that is heat labile |
|
|
K antigen |
Capsular antigen that is heat labile and found only in some encapsulated strains |
|
|
Examples of K antigen |
K1 antigen of E coli Vi antigen of Salmonella typhi |
|
|
Overt or primary pathogen names |
Salmonella Shigella Yersinia |
|
|
E coli |
Most significant org in genus Most common org in GI tract Used as a marker for fecal contam Most common cause of UTI in ppl Also cause CNS infections, diarrhea |
|
|
Distinctive colony morphology of E coli |
MAC ferments lactose,dry pink EMB- green metallic sheen |
|
|
Classification of E coli GI syndromes is based on |
Virulence factors Clinical presentation Epidemiology Different O and H serotypes |
|
|
5 major categories of diarrheagenic E coli |
Enterotoxigenic E coli (ETEC) Enteroinvasive E coli (EIEC) Enteropathogenic E coli (EPEC) Enterohemorrhagic E coli (EHEC) Enteroadherent E coli |
|
|
ETEC |
Travelers diarrhea, infant childhood diarrhea in tropical climates with poor sanitation conditions |
|
|
Mechanism of ETEC |
Hypersecretion of fluids and electrolytes into the intestinal lumen Doesn't penetrate mucosa so no PMNs/lactoferrin in stool |
|
|
Symptoms of ETEC |
Watery diarrhea, abdominal cramps No fever or vomiting |
|
|
EIEC |
Rare in US Affects children and adults |
|
|
EIEC mechanism |
Transmitted fecal oral route Organism penetrates and destroys intestinal mucosa |
|
|
EIEC symptoms |
Bloody mucous like stool Dysentery symptoms Invasive so PMNs present |
|
|
EPEC |
Causes infantile diarrhea Rare in adults Can become chronic |
|
|
EPEC symptoms |
Malaise, vomiting, diarrhea Mucous stools but not bloody Severe diarrhea in <1yrs old suspect |
|
|
EHEC |
Causes hemorrhagic colitis Potentially fatal in child/old E coli O157 H7 in this group |
|
|
EHEC symptoms |
Watery then bloody diarrhea, abdominal cramps, low or no fever Hemorrhagic colitis Few to no leukocytes |
|
|
Hemorrhagic colitis |
Diarrhea, colitis, hemolytic uremic syndrome |
|
|
Source of EHEC |
Processed/undercooked ground meat, unpasteurized dairy, apple cider, bean sprouts, spinach, raw cookie dough |
|
|
EHEC produces 2 cytotoxins |
Verotoxin I Verotixin II |
|
|
Vero cells |
African green monkey kidney cells Destroyed by verotoxins |
|
|
Verotoxins |
Aka Shiga toxins or Shiga like toxins |
|
|
Culture for Ecoli O157 |
MAC agar with sorbitol instead of lactose Doesn't ferment sorbitol so it will appear clear Must be serotype identified before being reported as O157 |
|
|
Differentiating Ecoli O157 on MAC |
Cant differentiate it from other Ecoli on regular MAC must use sorbitol |
|
|
Rapid testing for EHEC |
EIA kits available (EHEC test) Test for ST1 and ST2 so it picks up other strains not just O157 More sensitive than culture must serotype to ID as O157 |
|
|
Enteroadherent Ecoli |
Diffusely adherent Enteroaggregative |
|
|
Diffusely adherent Ecoli |
DAEC Associated with UTIs and pediatric diarrhea |
|
|
Enteroaggregative Ecoli |
EAEC Associated with persistent pediatric diarrhea |
|
|
Extra intestinal Ecoli infections |
The most common cause of septicemia and meningitis in neonates |
|
|
K1 capsular antigen |
Associated with virulence of neonatal strains of Ecoli |
|
|
Klebsiella, enterobacter, serratia |
Opportunistic/ nosocomial infections |
|
|
Klebsiella spp |
K pneumoniae most common isolate Colonize respiratory tract of hospitalized patients |
|
|
K pneumoniae |
Has polysaccharide capsule Virulence factor that results in mucoid colony (fish eye on MAC) |
|
|
Disease states caused by klebsiella |
UTI, wound, bacteremia, pneumonia |
|
|
Differentiate klebsiella pneumoniae from klebsiella oxytoca |
K pneum is indole neg K oxytoca is indole pos |
|
|
ESBL and carbapenemase production is associated with |
Klebsiella spp |
|
|
Enterobacter spp |
E cloacae and E aerogenes most common isolates Tend to be antibiotic resistant Isolated from wounds,urine,blood,csf |
|
|
Cronobacter (enterobacter) sakazakii |
Yellow pigmented |
|
|
Cause of neonatal meningitis associated with powdered infant formula |
Enterobacter spp |
|
|
Serratia spp |
Slow lactose fermenter Opportunistic associated with nosocomial outbreaks in hospitals Wide resistance to antibiotics Produce red or pink pigment |
|
|
Common serratia spp |
S. Marscescens S. Liquefaciens S. Adorifera |
|
|
Serratia adorifera |
Smells like rotten potatoes |
|
|
Proteus, providencia, morganella |
PAD+ (phenylalanine deaminase) Lactose neg (clear on MAC) |
|
|
Proteus mirabiliis and sometimes proteus vulgaris |
Swarming on BAP Burnt chocolate cake odor |
|
|
Differentiate P vulgaris and P mirabiliis |
P mirabiliis is indole - ornithine + P vulgaris is indole + ornithine - |
|
|
What 2 species of enterobacteriaceae can you presumptively ID |
E coli P mirabiliis |
|
|
Salmonella spp |
Inhabit GI tract of coldblooded animals (reptile), rodents, birds Transmitted to humans by animals Or uncooked poultry, eggs, unpasteurized dairy Not part of normal human flora |
|
|
Forms of Salmonellosis |
Gastroenteritis Typhoid fever Bacteremia Carrier state |
|
|
Gastroenteritis from salmonella |
Ingested of contaminated food "Food poisoning " Most common form of salmonellosis |
|
|
Infective dose of salmonella GI disease |
10⁶ or 1 million |
|
|
Symptoms of gastroenteritis (salmonella GI disease) |
8-36 hrs after ingestion Nausea, vomiting, fever, chills, diarrhea, abdominal pain |
|
|
Gastroenteritis (salmonella GI disease) treatment |
Usually self limiting Doesn't usually need antibiotics Antibiotic treatment is thought to prolong or cause carrier state |
|
|
Typhoid fever |
Aka enteric fever Ingestion of contaminated food from a human carrier (not from animals) |
|
|
Symptoms of typhoid fever |
Prolonged fever, bacteremia, involvement of reticuloendothelial system, disseminate to other organs 9-14 hours after ingestion |
|
|
Where typhoid fever is caught |
Tropical countries with poor sanitation Lab workers |
|
|
Salmonella typhi is resistant to |
Gastric acid |
|
|
Infection route if salmonella typhi (typhoid fever) |
Enters lymph system, then blood, then spleen, liver, bone Engulfed and multiplies intracellularly and later re-released into blood Repeated cycles of febrile illness May be isolated from blood or stool |
|
|
Bacteremia of salmonella |
Non typhoidal salmonella Intermittent bacteremia and prolonged fever May or may not have extra intestinal focus |
|
|
Carrier state of salmonella |
Previously infected individuals may harbor organisms in gall bladder Organism excreted in stool which is how others get infected May be treated with antibiotics or gall bladder removal |
|
|
Salmonella spp may be differentiated by stereotyping of |
O- somatic and heat stabile H- flagellar and heat labile O- capsular and heat labile |
|
|
Virulence antigen of salmonella typhi is |
K antigen Test using antisera |
|
|
Shigella |
Closely related to Ecoli Cause bacillary dysentery Humans are only reservoir and transmitted via fomites Very invasive and penetrative |
|
|
Bacillary dysentery |
Blood mucus and pus in stool Short self limiting with fever and diarrhea |
|
|
Predominant strains of shigella |
Shigella sonnei Shigella flexneri |
|
|
Transmission of shigella |
Person to person or via fomites Personal hygiene- affects daycares, crowded conditions Very communicable and small infections dose (200 organisms) |
|
|
Mechanism of shigella infection |
Penetration of intestinal epithelium, inflammation shedding of intestinal lining, ulcers Orgs multiply in sm intestine and move to colon Doesn't disseminate to organs |
|
|
Symptoms of shigella |
Asymptomatic to severe High fever, chills, abd. Cramps, Tenesmus Bloody stools with mucous and pmns |
|
|
Tenesmus |
Ineffective painful straining of bowels, sensation of having to go but not producing significant quantities Especially shigella dysenteriae |
|
|
ID of shigella |
Isolate in culture 1-3 days after symptoms |
|
|
Yersinia enterocolitica |
Animal reservoir (pig, cat, dog) or water streams Survive and thrive in cold temps |
|
|
Infection route of yersinia |
Ingestion of contaminated food like spam RBC contamination (likes cold temp) Typically mild and self limiting |
|
|
Symptoms of yersinia |
Acute enteritis-fever, abd pain, diarrhea (bloody?), mostly in children Gastroenteritis mimic appendicitis- in older children adults |
|
|
Gram staining of yersinia |
Gram neg coccobacilli with bipolar staining |
|
|
CIN agar |
Selective for yersinia, inhibits normal flora |
|
|
Yersinia pestis |
Causes plague Bubonic/glandular or pneumonic Transmitted by flea bites Symptoms 2-5 days after infection High fever swollen lymph nodes (buboes) |
|
|
Pneumonic plague |
Secondary to bubonic when organism enters blood stream and travels to lungs High fatality if untreated Respiratory transmission |
|
|
Y pestis gram stain |
Gram neg bacilli short plump Bipolar staining with methylene blue or Watson stain |
