Enterobacteriaceae/Salmonella Flashcards
Gram-negative bacillus
Member of the family Enterobacteriaceae
Over 2500 serotypes / strains characterized by “O” and “H” antigens (most common strains have been given what appear to be “species” names)
Salmonella spp.
Most common human Salmonella spp.
Salmonella enterica, serovar Typhi
S. enterica, serovar. Enteritidis
ingestion of contaminated food and water
Frequent normal flora of poultry (turkeys, chickens), livestock, rodents, reptile (turtle)
Many bacteria are destroyed by stomach acids, so ingestion of large quantity are needed to initiate infection
salmonella
Transmitted by contaminated food and water, especially
(a) Meat products not properly cleaned or cooked
(b) Eggs and dairy products
(c) Other foods prepared on contaminated surfaces (e.g. cutting boards)
salmonella
(enterocolitis syndrome) (Salmonella food poisoning) – caused by Salmonella enteritidis (and numerous other serotypes)
Acute gastroenteritis
Bacteria invade the intestinal mucous membranes causing an acute inflammatory reaction in the subepithelial tissue
ii. Symptoms include sudden onset of diarrhea (rarely bloody) and vomiting along with fever about 6 to 48 hours after consumption of contaminated food or water;
Salmonella enteritidis
symptoms persist 2 to 7 days (just a framework)
Typhoid fever
enteric fever (salmonella typhi & paratyphi)
Bacteria invade epithelial cells of terminal portion of small intestine and then into the lymphoid follicles where they multiply
(salmonella typhi, paratyphi)
Enteric Fever (Typhoid fever)
Localizes in gallbladder, spleen, liver, bones (occasionally)
Bacteria invade epithelial cells of terminal portion of small intestine and then into the lymphoid follicles where they multiply
Bacteria migrate to the blood stream, the fever period begins, and rose spots appear on the skin. Local necrosis can lead to hemorrhage and lesions
Enteric Fever (Typhoid fever)
Fever begins 10-14 days after ingestion of bacteria
• Headache, myalgia, malaise persist for about 5-10 days
• Gastrointestinal symptoms begin about 15-20 days after ingestion of bacteria
Enteric Fever (Typhoid fever) — Salmonella Typhi & Paratyphi
Gram-negative bacillus; member of the family Enterobacteriaceae
shigella and salmonella
Gram-negative bacillus; member of the family Enterobacteriaceae
shigella
salmonella
E. Coli
Pathogenicity – Shigellosis or Bacillary Dysentery –enterocolitis syndrome
shigella
Pathogenicity – Shigellosis or Bacillary Dysentery –enterocolitis syndrome
shigella
Endotoxin - potent and is present in all strains
Produce Shiga Toxin (AB-type) – disrupts protein synthesis – damages the intestinal epithelium
Neurotoxin and enterotoxin produced by S. dysenteriae type I
Some strains of S. flexneri produce enterotoxins
Shigella spp.
Incubation: 12-48 hours depending on dose of microbes (10-100 bacteria) with symptoms lasting 1-3 days
Symptoms: Diarrhea (liquid stools), lesions in the colon producing pus and blood in feces (dysentery), and fever
Shigella spp.
Attach/penetrate muscosal epithelium of intestine
Bacterial multiplying cause host cell death and bleeding
Bacteria release endotoxin, causing fever, inflammation & local damage (ulcerations/pus/bleeding)
Exotoxin causes fluid loss (diarrhea)
shigellosis dz progression
Big need with tx for gastroenteritis?
rehydration
Escherichia coli
Gram-negative bacillus; member of family Enterobacteriaceae
A predominant normal flora of intestinal tract; a ____ refers to those members that are normal flora of the intestinal tract; primarily Escherichia, Klebsiella, Enterobacter
coliform
causes 75% to 85% of all UTIs; mostly in outpatient females
E. Coli
(a) Symptoms: Flank pain, dysuria (painful urination), fever
(b) Route of infection: Bacteria attach to epithelial cells of the urinary tract by means of fimbrae
(c) Source: Fecal contamination – poor personal hygiene or nosocomial (e.g. catheterization)
E. Coli UTI/cystitis:
(a) Symptoms: Flank pain, dysuria (painful urination), fever
(b) Route of infection: Bacteria attach to epithelial cells of the urinary tract by means of ____
fimbrae
Causes “Traveler’s Diarrhea” due to cholera-like toxin – several antigenic types involved
Enterotoxic E. coli (ETEC)
(a) Bacteria enter small intestines and release heat-labile (LT) and/or heat-stable (ST) enterotoxins (genes on plasmids)
(b) Causes hypersecretion of water and chlorides into the lumen. Also inhibits absorption of sodium
(c) Symptoms: Cramps fever, dehydration and mild (to occasionally profusely) watery stools without mucus and blood (8-12 unformed stools per day and may last 4-5 days)
Enterotoxic E. coli (ETEC)
similar to cholera toxin
Hemorrhagic colitis
Enterohemorrhagic E. coli (EHEC)
Invades intestinal epithelium and produces verotoxin (also known as Shiga Toxin, ST), and causes shigella-like symptoms – several antigenic types involved [Sometimes referred to as Shiga Toxin-producing E. coli (STEC) or Enteroinvasive E. coli (EIEC)]
Enterohemorrhagic E. coli (EHEC) – Hemorrhagic colitis
Symptoms: Severe abdominal pain (cramps) and watery diarrhea followed by grossly bloody diarrhea and inflammation; “No fever”
(c) May cause hemolytic uremic syndrome (HUS) [hemorrhage of kidney tissue] – about 10% of cases
Enterohemorrhagic E. coli (EHEC) – Hemorrhagic colitis
How to differentiate between EHEC and shigellosis?
Also EIEC…
Lab work
Shigellosis - fever
EHEC - “no fever”
Similar toxins carried on plasmid
May cause hemolytic uremic syndrome (HUS) [hemorrhage of kidney tissue] – about 10% of cases
Enterohemorrhagic E. coli (EHEC) – Hemorrhagic colitis
EHEC - hemorrhagic colitis mode of infection?
Ingestion of contaminated meat or other food products
(Cattle, chickens and other animals – carry as fecal flora)
GROUND MEAT
(a) Produce Shigella-like toxins (stx1, stx2)
(b) Syndrome is similar to shigellosis with profuse bloody diarrhea, high fever, cramps, vomiting (12-72 hr)
(c) Utilize adhesion proteins to bind to and enter intestinal cells – highly invasive
Enteroinvasive E. coli (EIEC) and Shiga-like Toxin-producing E.coli (STEC)
inflammation and purulent discharge due to nosocomial and traumatic spread of fecal contamination
E. Coli wound infection
(1) Routine culture and biochemical identification does not determine toxin or antigenic type, so specific toxin test and/or antigen tests may be useful
(2) Antimicrobic susceptibility test needed to determine drug resistant strains
Lab ID of E. Coli
Found in the environment and animals. Transmitted in contaminated pork, milk, water, tofu
Etiologic agent of sporadic mild gastroenteritis with BLOODY diarrhea, vomiting, and low fever
Yersinia enterocolitica
(1) Invasive and necrotic to intestinal lining
(2) Invades Peyer’s patches and disseminates to liver and spleen.
(3) Usually self-limiting; sometimes leads to chronic inflammatory diseases
(4) May shed in stool for 90 days after symptoms
Yersinia enterocolitica
Gram-negative bacillus
Biological threat agent – BSAT (Biological Select Agents and Toxins
Yersinia pestis
Etiologic agent of Bubonic & Pneumonic Plague
(
(1) Bubonic Plague – lymph node infection
(2) Pneumonic Plague – pneumonitis
(3) Septicemia – bloodstream infection (disperses bacteria systemically)
(4) Necrotic factors – leads to “Black Death”
Yersinia pestis
Virulence Factors
(1) Antiphagocytic
(a) Protein capsule
(b) Various proteins inhibit phagocytosis, suppress cytokine production; intense inflammatory response
(2) Plasminogen activator protease
(a) Degrades C3b and C5a – prevents opsonization & phagocytic migration
(b) Degrades fibrin clots – permits spread and necrosis
Yersinia pestis
Antiphagocytic
Plasminogen activator protease
adherence factors
intense inflammatory rxn
necrotic factors
Yersinia pestis
Transmitted by fleas or direct contact with tissues of infected animals or oral droplets coughed up during pneumonia
Yersinia pestis
pneumonia and urinary tract infections (UTI)
Klebsiella pneumoniae
bacteremia and UTI, especially in burn patients
Enterobacter spp
UTI, wound
Proteus spp.
burn-wound, UTI
Providencia spp.
gastroenteritis (cholera-like and dysentery-like) and cellulitis (rare necrotizing fasciitis)
Aeromonas spp.
diarrhea & occasional dysentery, especially after ingesting raw seafood; Occasional complications include invasive cellulitis, bacteremia, peritonitis, meningoencephalitis. Most are resistant to numerous antimicrobics
Plesiomonas shigelloides
