Gram Negative Pathogens Part 2 (Enterics cont) Flashcards
What virulence factors allow Enteropathogenic E. coli (EPEC) to produce watery diarrhea?
Enteroaggregative Fimbriae (EAF) pilus allowing tight adherence
What kind of diarrhea does EPEC produce?
Watery diarrhea with:
Vomiting
Fever in infants
Diarrhea in infants is most likely linked with what kind of E. coli?
Enteropathogenic E. coli
What virulence factors allow Enterotoxigenic E. coli (ETEC) to produce watery diarrhea?
Colonization Factor A (CFA) pilus
LT and/or ST exotoxin
What kind of E. coli usually produces Traveler’s diarrhea (Montezuma’s revenge)?
Enterotoxigenic E. coli
What kind of E. coli usually produces diarrhea in children aged 5 years old and below?
Enterotoxigenic E. coli
What kind of diarrhea does ETEC produce?
Watery diarrhea
What virulence factors allow Enterohemorrhagic E. coli (EHEC) to produce bloody diarrhea?
CFA pilus
Capsule
Shiga-like toxin (verotoxin) (cytotoxic effects on host cells)
What type of diarrhea does EHEC produce?
Bloody diarrhea (hemorrhagic colitis) without fever or pus; may be associated with hemolytic uremic syndrome (hemolytic anemia, acute kidney injury, and thrombocytopenia)
This kind of bloody diarrhea has been linked to infected meat products prompting suspicion for cattle reservoir.
EHEC induced bloody diarrhea
What virulence factors allow Enteroinvasive E. coli (EIEC) to produce bloody diarrhea?
Small amount of Shiga toxin allowing invasion of the intestinal mucosal epithelial cells
What type of diarrhea does EIEC produce?
Bloody diarrhea with pus and WBC in stool; associated with fever
This type of E. coli produces bloody diarrhea with pus and WBC in stool which may be associated with fever.
Enteroinvasive E. coli
This type of E. coli produces blood diarrhea without fever or pus and may be associated with hemolytic uremic syndrome.
Enterohemorrhagic E. coli
This type of diarrhea is common in children in developing countries.
Enteroinvasive E. coli (EIEC) - induced bloody diarrhea
This type of E. coli produces acute or chronic diarrhea (>14 days)
Enteroaggregative E. coli
What virulence factors allow Enteroaggregative E. coli (EAEC) to produce bloody diarrhea?
Exotoxin (ST), enterotoxin, and hemolysin
This type of E. coli usually causes food borne diarrhea in developed countries and causes the cases of diarrhea developing countries.
Enteroaggregative E coli.
T/F. Shigella dysenteriae appears as slender rods in young cultures and cocco-bacillus when mature.
False. Slender rods when mature; cocco-bacillus when young
T/F. Shigella dysenteriae may be aerobes or facultative anaerobe.
True.
T/F. Shigella dysenteriae can ferment glucose.
True.
T/F. Shigella dysenteriae can ferment lactose.
False. Cannot ferment lactose
T/F. Shigella dysenteriae can produce hydrogen sulfide.
False. Cannot produce hydrogen sulfide
T/F. Shigella dysenteriae can produce gas but rarely.
True
T/F. Shigella dysenteriae has A/K/G+-/HS-
True. Can ferment glucose but not fructose, some produces gas, but cannot produce hydrogen sulfide
What are the virulence factors associated with Shigella dysenteriae?
Low infectious dose
Shiga toxin
This microorganism has a very low infectious dose at just 10^2 cells.
Shigella dysenteriae
What type of diarrhea does Shigella dysenteriae produce?
Bloody diarrhea with mucus and pus production associated with fever and abdominal pain.
Treatment for Shigella dysenteriae infection
No anti-diarrheal drugs (treatment limited to fluid replacement therapy)
Oral fluid replacement
IV fluid
Antibiotics for severe infections
T/F. Salmonella are often commensal but can be pathogenic.
True
What are the three presentation of Salmonella infection?
enteritis, enteric fever, and systemic infections
Transmission of Salmonella is primarily via:
contaminated water and contaminated food or animal products
T/F. Salmonella appears rod shaped.
True.
T/F. Salmonella is anaerobic bacterium.
False. Facultative anaerobic bacterium.
T/F. Salmonella can ferment lactose but not sucrose.
False. Cannot ferment both
T/F. Salmonella cannot produce hydrogen sulfide.
False.
T/F. Salmonella can produce gas.
True.
T/F. Salmonella is A/K/G+/S+
True. Can ferment glucose only; produces gas; produces H2S
What are the virulence factors associated with Salmonella?
Capsule (Vi antigen)
Motile
Siderophores
T/F. Salmonella is a motile organism
True.
Salmonella capsule is in the form of?
Vi antigen
This microorganism causes typhoid (enteric) fever characterized by fever, headache, abdominal pain, rose spots on chest and abdomen.
Salmonella
This presentation of Salmonella infection is characterized by fever, headache, abdominal pain, rose spots on chest and abdomen.
Typhoid enteric fever
This microorganism causes enterocolitis characterized by nausea, headache, vomiting, watery diarrhea (some may contain mucous or blood), abdominal cramping, and fever.
Salmonella
This presentation of Salmonella infection is characterized by nausea, headache, vomiting, watery diarrhea (some may contain mucous or blood), abdominal cramping, and fever.
Enterocolitis
What are the clinical presentations of Salmonella infection?
Typhoid enteric fever
Enterocolitis
Carrier state - infected hosts become carrier of the organism and proliferate again
Sepsis
What is the treatment for Salmonella induced typhoid fever?
Ciprofloxacin/ceftriaxone
What is the treatment for Salmonella induced enterocolitis?
fluid and electrolyte replacement
T/F. Klebsiella is capsulated and motile.
False. Capsulated but not motile
This microorganism produces pneumonia associated with production of currant jelly sputum characterized by a dark reddish to brownish appearance.
Klebsiella
Clinical presentation of Klebsiella infection
UTI
Pneumonia with currant jelly sputum
associated with high mortality rate
Treatment for Klebsiella
Cephalosporin
Ciprofloxacin
T/F. Proteus mirabilis is a non-motile organism.
False. Motile organism
This microorganism produces UTI associated with production of alkaline urine which promotes stone formation.
Proteus mirabilis
Clinical presentation of P. mirabilis infection
UTI with alkaline urine
Sepsis
This microorganism is a part of the normal gut flora and is characterized by swarming in culture.
P. mirabilis
Treatment for P. mirabilis infection
Ampicillin
TMP-SMX
T/F. Enterobacter spp. are capsulated and non motile.
False. Capsulated and motile.
This bacterium is implicated in Healthcare Associated Infections causing pneumonia, UTI, and characteristically wound and device infections.
Enterobacter spp. and Serratia marcescens
This bacterium is part of the skin and gut microflora and is commonly found in environment and food.
Enterobacter spp.
This bacterium is multi-drug resistant notably B-lactamase resistant which is a trait encoded by the ampC gene.
Enterobacter spp.
What is the only treatment available for Enterobacter spp. infections?
Carbapenem
This bacterium is characterized by varied ways of transmission and a red-pigmented colonies in culture.
Serratia marcescens.
This bacterium causes similar diseases as ETEC but in more severe form.
Vibrio cholerae
What is the usual route of infection of V. cholera?
Fecal-oral route (usually contaminated water)
T/F. V. cholerae is a motile organism.
True. Allowed by the presence of a polar flagellum
What is the shape of V. cholerae?
Comma-shaped, curved rods
T/F. V. cholerae is anaerobic organism.
False. Aerobic
T/F. V. cholerae can ferment sucrose.
True.
T/F. V. cholerae is a halophilic organism.
True. Requires 0.5-4.5% NaCl
T/F. V. cholerae grows optimally in low pH.
False. grows optimally at pH 8.5-9.5
What are the virulence factors associated V. cholerae?
Fimbriae
Choleragen toxin (AB toxin)
The choleragen toxin of V. cholerae is in the form of?
AB toxin
A subunit - activates G-protein
B subunit - binds to GM1 ganglioside
This organism causes watery diarrhea characterized by rapid fluid loss (1L/hr) and no pus.
V. cholorae
Treatment for V. choloerae infection.
Fluid and electrolyte replacement
Doxycycline
Fluoroquinolone
What medium is usually used to detect V. cholerae?
Thiosulfate-Citrate-Bile-Sucrose (TCBS) agar in conjunction with microscopy
This bacterium characteristically produces duodenal and stomach ulcers.
Helicobacter pylori
What is the shape of H. pylori?
Spiral or curved rods
T/F. H pylori is a motile organism.
True. Allowed by a single or tuffs of polar flagella
T/F. H pylori is aerophilic.
False. Microaerophilic
This organism characteristically has a relatively longer incubation period at 14 days.
H. pylori
T/F. H pylori is catalase positive, oxidase negative and urease positive.
False. catalase positive, oxidase positive, and urease positive.
What medium is usually used to isolate H. pylori?
medium enrich with blood, e.g., chocolate agar
Virulence factors associated with H. pylori
Adhesion factors
Mucinase, and phospholipase for tissue damage
Treatment for H. pylori.
Bismuth,
Metronidazole
Proton pump inhibitors
Tetracycline
Clarithromycin
Amoxicillin
What medium is usually used to detect Shigella dysenteriae?
MAC or EMB, HE, and XLD (for differential and selective growth of Gram negative rods)
What medium is usually used to detect Salmonella?
MAC or EMB, HE, and XLD (for differential and selective growth of Gram negative rods)