03 - Enterobacteriaceae Family 14 - 19 Flashcards
What is the gram stain of Salmonella spp.?
Gram-negative bacillus
(1) Member of the family Enterobacteriaceae
(2) One major species: Salmonella enterica
(3) Over 2500 serotypes / strains characterized by “O” and “H” antigens (most common strains have been given what appear to be “species” names). EXAMPLES: Salmonella enterica, serovar Typhi; etc etc
(4) 95% of isolates are in antigenic groups A, B, C1, C2, D, E, F, G, H, and Vi. In the USA, antigenic groups B and D predominate (40% of about 50,000 reported cases annually)
Salmonella
what is the one major species of Salmonella?
Salmonella enterica
How many serotypes of Salmonella and characterized by what?
Over 2500 serotypes (strains characterized by “O” and “H” antigens
Salmonella
Transmission and Source of infection?
– ingestion of contaminated food and water
(1) Frequent normal flora of poultry (turkeys, chickens), livestock, rodents, reptile (turtle)
(2) 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)
(3) Many bacteria are destroyed by stomach acids, so ingestion of large quantity are needed to initiate infection
Four pathogens that cause ACUTE gastroenteritis?
Salmonella enteritidis
Staph aureus
Bacillus cereus (1-6hrs after ingestion vomit THEN diarrhea within 6 -24 hrs )
Vibrio vulnificus
Pathogenicity of Salmonella enteritidis
i. invade where causing rxn where?
ii. symptoms?
i. 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; symptoms persist 2 to 7 days
Generally no ABX
Acute gastroenteritis (enterocolitis syndrome) (Salmonella food poisoning) – caused by ?
Salmonella enteritidis (and numerous other serotypes)
gastroenteritis AKA
enterocolitis syndrome
which pathogen causes gastroenteritis and is similar to Salmonella?
Campylobacter jejuni
Enteric Fever (Typhoid fever) caused by
Salmonella Typhi & Paratyphi
Pathogenicity of Typhoid Fever AKA ?
i. Bacteria invade epithelial cells of terminal portion of small intestine and then into the lymphoid follicles where they multiply
ii. 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
• 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
iii. Localization of bacteria in gallbladder, spleen, liver, and sometimes bones
iv. Carrier state (excretion for 3 months) develops in about 5% of patients - Gallbladder is where most bacilli are located in carriers
AKA Salmonella Typhi & Paratyphi
Tx and control of Salmonella Typhi & Paratyphi -(Enteric Fever / Typhoid Fever)
ABX useful lik [Chloramphenicol (14 days), amoxicillin, or ceftriaxone (IV) (5 days), or trimethoprim/sulfamethoxazole]
(1) Culture and biochemical identification and “O” antigenic group designation
(2) Antimicrobic susceptibility test needed to determine drug resistant strains
(1) Culture and biochemical identification with antigenic identification
(2) Antimicrobic susceptibility testing needed to determine antibiotic resistant strains
a. Gram-negative bacillus; member of the family Enterobacteriaceae
b. Four species are determined by antigenic grouping
Shigella spp.
Shigella spp. name all four species…
(1) S. dysenteriae – Antigenic group A – Least frequently isolated in the U.S. – causes a more severe form of dysentery than the other species
(2) S. flexneri – Antigenic group B – 25% of Shigella species isolated in the U.S.
(3) S. boydii – Antigenic group C – Rare in U.S., only 0.6% of isolates
(4) S. sonnei – Antigenic group D – Most frequent isolate (74% of isolates)
Transmission and Epidemiology of Shigella spp.
(1) Transmitted by fecal-oral route
(2) Sources of infection – ingestion of food and water contaminated with feces
(3) Infection can be establish by about 200 bacteria
(4) Children under 10 years of age account for over 2/3 of all cases
dysentery w/o cellulitis means it’s of this species
shigella
Transmission and Epidemiology of shigella
(1) Transmitted by fecal-oral route
(2) Sources of infection – ingestion of food and water contaminated with feces
(3) Infection can be establish by about 200 bacteria
(4) Children under 10 years of age account for over 2/3 of all cases
Pathogenicity – Shigellosis or Bacillary Dysentery –enterocolitis syndrome
(1) Incubation: 12-48 hours depending on dose of microbes (10-100 bacteria) with symptoms lasting 1-3 days
(2) Toxin production
(a) Endotoxin - potent and is present in all strains
(b) Exotoxin
i. Produce Shiga Toxin (AB-type) – disrupts protein synthesis – damages the intestinal epithelium
ii. Neurotoxin and enterotoxin produced by S. dysenteriae type I
iii. Some strains of S. flexneri produce enterotoxins
(c) Invasive enzymes
(3) Symptoms: Diarrhea (liquid stools), lesions in the colon producing pus and blood in feces (dysentery), and fever
Disease Progression of Shigella spp
Disease progression
(a) Organisms attach to & penetrate intestinal mucosal epithelial cells
(b) Bacteria multiply intracellularly causing mucosal epithelial cells to die and slough off with some bleeding
(c) Bacteria release an endotoxin that stimulates fever and an inflammatory response causing local damage (ulcerations, pus, and bleeding)
(d) Exotoxin causes fluid loss (diarrhea)
Shigella spp.
Treatment and control – Rehydration and electrolyte replacement; acute/severe illness is usually treated with…
a third-generation cephalosporin (widespread resistance to others)
Laboratory diagnosis of Shigella spp.
(1) Culture and biochemical identification and “O” antigenic group designation
(2) Antimicrobic susceptibility test needed to determine drug resistant strains
Escherichia coli
a. Gram-negative bacillus; member of family Enterobacteriaceae
b. Taxonomy based on numerous “O” and “H” antigen combinations (like salmonella)
c. A predominant normal flora of intestinal tract; a coliform… which refers to?
Coliform – refers to those members that are normal flora of the intestinal tract; primarily Escherichia, Klebsiella, Enterobacter
What are the major presentations of Escherichia coli (etiologic agent)
(1) Urinary tract infection (UTI) (cystitis)
(2) Enterotoxic E. coli (ETEC) – Traveler’s Diarrhea
(3) Enterohemorrhagic E. coli (EHEC) – Hemorrhagic colitis
(4) Enteroinvasive E. coli (EIEC) and Shiga-like Toxin-producing E.coli (STEC)
(5) Enteropathogenic E.coli (EPEC)
(6) Enteroaggregative E.coli (EAEC)
(7) Wound infection (infrequent) – inflammation and purulent discharge due to nosocomial and traumatic spread of fecal contamination
Urinary tract infection (UTI) (cystitis) – causes 75% to 85% of all UTIs; mostly in outpatient females
Escherichia coli
Enterotoxic E. coli (ETEC) – Causes…
“Traveler’s Diarrhea” due to cholera-like toxin – several antigenic types involved
– Hemorrhagic colitis
Enterohemorrhagic E. coli (EHEC)
Laboratory identification of Escherichia coli
(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
Urinary tract infection (UTI) (cystitis) – causes 75% to 85% of all UTIs; mostly in outpatient females
(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)
Escherichia coli = #1 cause of UTI
(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) – Causes “Traveler’s Diarrhea” due to cholera-like toxin – several antigenic types involved
(a) 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)]
i. Bacteria invade and multiply inside epithelial cells
ii. Necrosis of epithelial cells
Enterohemorrhagic E. coli (EHEC) – Hemorrhagic colitis
produces verotoxin (also known as Shiga Toxin, ST), and causes shigella-like symptoms
[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”
Enterohemorrhagic E. coli (EHEC) – Hemorrhagic colitis
May cause hemolytic uremic syndrome (HUS) [hemorrhage of kidney tissue] – about 10% of cases (ONLY PATHOGEN TO DO THIS ON SLIDES)
Enterohemorrhagic E. coli (EHEC) – Hemorrhagic colitis
(d) Primary antigenic types: O157:H7 (about 80% of cases), O104:H4, O145, others
(e) Outbreaks cause thousands of cases of illness and dozens of deaths
(f) Mode of infection
i. Ingestion of contaminated meat or other food products
ii. Source: Cattle, chickens and other animals – carry as fecal flora
Enterohemorrhagic E. coli (EHEC) – Hemorrhagic colitis
O157:H7 think….
Enterohemorrhagic E. coli (EHEC) – Hemorrhagic colitis
(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)
Laboratory identification of Escherichia coli
(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
(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
Yersinia enterocolitica
see Peyer’s patches think…
Yersinia enterocolitica
Gram-negative bacillus (Family Enterobacteriaceae)
Biological threat agent – BSAT (Biological Select Agents and Toxins) - refers to intentional use by terrorist or military.
Yersinia pestis
PLAGUE think
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
(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
(3) Adherence factors
(4) Intense inflammatory reaction; and septicemia
(5) Necrotic factors – Black Death
Yersinia pestis
Transmitted by fleas or direct contact with tissues of infected animals or oral droplets coughed up during pneumonia (if plague like symptoms it is this, but remember there are multiple pathogens spread by fleas!
f. Geographic distribution – many localities around the world (almost all bubonic)
(1) North America: 10-15 cases per year
(2) World: 1000-3000 cases per year
Yersinia pestis
Additional Enterobacteriaceae of Significance
Occasional opportunistic or nosocomial pathogens – usually fecal source
a. Klebsiella pneumoniae – pneumonia and urinary tract infections (UTI)
b. Enterobacter spp. – bacteremia and UTI, especially in burn patients
c. Proteus spp. – UTI, wound
d. Providencia spp. – burn-wound, UTI
e. Aeromonas spp. – gastroenteritis (cholera-like and dysentery-like) and cellulitis (rare necrotizing fasciitis)
f. Plesiomonas shigelloides. –diarrhea & occasional dysentery, especially after ingesting raw seafood; Occasional complications include invasive cellulitis, bacteremia, peritonitis, meningoencephalitis. Most are resistant to numerous antimicrobics
produces verotoxin (also known as Shiga Toxin, ST), and causes shigella-like symptoms
[Sometimes referred to as Shiga Toxin producing E. coli (STEC) or Enteroinvasive E. coli (EIEC)]
Enterohemorrhagic E. coli (EHEC) – Hemorrhagic colitis
Most human cases of salmonella?
Salmonella Enteriticus Group B most common, but overall antigenic groups B & D are most common
gram negative bacillus &
dysentery (bloody stool)
shigella
shigella
think Bacillary Dysentery or Shigellosis
all gram negative have endotoxins (which cause the fever an inflammation)
apparently true said Murray while discussing Enterobacteriacaea Family
remember the fever and inflammation often come from the…
endotoxin
EHEC
think eHeC = Hamburger possibly
two ARTHRALGIA
Brucella pertussis
AND
Coxiella burnetti
ACUTE diarrhea
Salmonella enteritidis
Staph aureus
Bacillus cereus (1-6hrs after ingestion vomit THEN diarrhea within 6 -24 hrs )
Vibrio vulnificus
Salmonella food poisoning
Salmonella enteritidis
