Infectious Agents that cause Diarrhea Flashcards
To discuss bacterial agents causing diarrhea, specifically the following: –Escherichia colistrains –Salmonella –Shigella –Vibrio –Campylobacter –Clostridium –Bacillus cereus
facultative gram-negative rods
- lactose-fermentingcolonies on EMB or MacConkey’sagar
- green sheen on EMB agar
- typing by O and H antigens
Escherichia Coli
LACTOSE FERMENTERS
Nmemonics:LaCtose is KEE
. Grow in MacConKEE’s agar.
Citrobacter
Klebsiella
Escherichia coli
Enterobacter
Escherichia coli HABITAT and TRANSMISSION
•habitat is __________
human colon
Escherichia coli HABITAT and TRANSMISSION
colonizes the _____ and __________
vagina and urethra
•transmission of E.coli
–ascending infection in UT
I –during birth in neonatal meningitis
–fecal–oral route in diarrhea
Escherichia coli PATHOGENESIS
- pili
- flagellum (H)
- capsule (K)
- endotoxin(O)
- enterotoxins
•enterotoxins of E. coli
–HSTand HLTcause watery diarrhea
–verotoxin(Shiga-like)causes bloody diarrhea _____
( HUS)
ENTEROBACTERIACEAE
Think MESSY SPECK!
Morganella
Serratia
Escherichia
Proteus
Shigella
Enterobacter
Salmonella
Citrobacter
Yersinia
Klebsiella
Enterobacteriaceaedrink COFFEe!
Capsular antigen (K)
Oantigen
Flagellarantigen (H)
Ferments glucose
Enterobacteriaceae
•URINARY TRACT INFECTION
–most common cause of community-acquired UTI
•NEONATAL MENINGITIS –2ndmost common cause
Escherichia coli SPECTRUM OF DISEASE
NEONATAL MENINGITIS
Nmemonic: B –E –L
Bgroup streptococci (S. agalactiae)
Escherichia coli
Listeriamonocytogenes
What is the strain of E.coli that cause watery diarrhea?
ETEC
(Entero Toxigenic E. coli)
What is the strain of E.coli that cause long duration of diarrhea, mostly in infants and often in developing country?
EnteroPATHOGENIC E.coli
**( EPEC) **
E.coli strain that cause bloody diarrhea, hemorrhagic colitis and HUS?
Enterohemorrhagic E.coli
(EHEC)
What strain of E.coli that cause bloody diarrhea?
EnteroINVASIVE E.coli
EIEC
What strain of E.coli that cause PERSISTENT WATERY DIARRHEA in children and in patients with HIV?
EnteroAdherent E.coli
EAEC
Escherichia coli TREATMENT and PREVENTION
•TREATMENT –Ampicillinor sulfonamides for UTI –3°cephalosporinsfor meningitis and sepsis
–Rehydration is effective in traveler’s diarrhea
•PREVENTION –limiting urinary catheterization, switching IV lines promptly, drinking boiled water
CHARACTERISTICS
- facultative gram-negative rods
- non-lactose-fermenting
- produces H2S
- Wida ltest detects antibodies in patient’s serum
- cultured in XLD medium
Salmonella spp.
What serologic tests Salmonella spp antibodies in patient’s serum,?
Widal test
Salmonella spp. HABITAT and TRANSMISSION
•HABITAT –__________
human colon only (S. typhi)
NOTE : –enteric tract of humans and animals
, e.g., chickens and domestic livestock (S. enteritidis)
How is Salmonella transmitted?
TRANSMISSION –fecal–oral route
Salmonella spp. PATHOGENESIS
•enterocolitis(S. enteritidis/ S. typhimurium)
•enterocolitis(S. enteritidis/ S. typhimurium)
–invasion of the epithelial and subepithelialtissue of the small and large intestines
–infectious dose is high
•gastrectomyor use of antacids lowers the infectious dose significantly
Salmonella spp. PATHOGENESIS •typhoid fever (S. typhi)
–due to Vi (virulence) capsular antigen
–organisms enter, multiply in Peyer’spatches, and then spread to reticulo-endothelial system
–predilection for invasion of the gallbladder, which can result in establishment of the chronic carrier state
•septicemia (S. choleraesuis
–bacteremiaresults in the seeding of many organs, with osteomyelitis,pneumonia, and meningitisas the most common sequelae
–commonly in patients with sickle cell anemia or cancer
Salmonella spp. SPECTRUM OF DISEASE
–incubation period of 12–48 hours
–nausea and vomiting and then progresses to abdominal pain and non-bloody diarrhea
•ENTEROCOLITIS
What are the spectrum of diseases of Salmonella
- Enterocolitis ( S. enteritidis or typhimirium)
- typhoid fever ( S. typhi)
- Septicemia ( S. choleraesuis)
What is the incubation fever of enterocolitis in Salmonella?
12 -48
TYPHOID FEVER –incubation period _________
Week Presentation Culture Source
5 to 21 days
WEEK 1 stepwise fever, anorexia, malaise, relative bradycardia and bacteremia : Culture source___________
Week 2 abdominal pain, bloating,constipation, rose spots, hepatosplenomegaly, jaundice: Culture source __________
Week 3 bleeding ,ileitis, pneumonia: Culture source:______________
Week 4 recovery or death: culture source :
POST chronic carrier state ____________
Blood, bone marrow
Urine, rose spots, bone marrow
Stool, bone marrow
Bone marrow
Bile, stool, bone marrow
Rose spots
Salmonella typhi
Salmonella spp. SPECTRUM OF DISEASE
______________–fever but little or no enterocolitisand then proceeds to focal symptoms associated with the affected organ
–frequently bone, lung, or meninges
•SEPTICEMIA
Salmonella spp. TREATMENT and PREVENTION
- TREATMENT
- PREVENTION –public health measures, e.g., sewage disposal, chlorination, hand washing, food safety –vaccines for S. typhi
–Ceftriaxone –Philippines:
amoxicillin, chloramphenicol, co-trimoxazole
CHARACTERISTICS
•non-lactose-fermenting
,gram-negative rods
- produce no gas from the fermentation of glucose
- do not produce H2S
- non-motile
- have O antigen
s •cultured in XLD medium
Shigellaspp.
Shigellaspp.
HABITAT and TRANSMISSION
- HABITAT –human colon only
- TRANSMISSION –fecal–oral route
SHIGELLA TRANSMISSION
4 Fs
Food
Fingers
Feces
Flies
Shigellaspp. PATHOGENESIS
•Shigellainvade the distal ileum and colon
_______________________
–low infectious dose (highly infectious)
–local inflammation accompanied by ulceration
_______________________
•most common cause of bacillary dysentery
–Shigellasonnei–Duval’s bacillus
____________________
- most severe form of bacillary dysentery
- most common cause of epidemic dysentery
–Shigelladysenteriaetype 1 –Shiga bacillus
•some produce an enterotoxin(______________
Shiga toxin)
Eponyms
•Group A –
Shigella dysenteriae
–Shigelladysenteriaetype I –Shiga bacillus
–Shigelladysenteriaetype 2 –Schmitz bacillus
” A.D”
•Group B –_______________
”
–Shigellaflexneri
- –Flexner’s bacillus;
- Hiss
- Russell’s bacillus
” Boyfriend”
•Group C
–Shigellaboydii
- –Newcastle Manchester bacillus
“CowBoy”
•Group D ___________
–Shigellasonnei
- –Duval’s bacillus
” Dad and Son”
Shigellaspp. SPECTRUM OF DISEASE
_____________ –incubation period: 1–4 days
–fever and abdominal cramps, followed by diarrhea, initially watery then bloody
–diarrhea frequently resolves in 2 or 3 days
•BACILLARY DYSENTERY
Shigellaspp. TREATMENT and PREVENTION
•TREATMENT –fluid and electrolyte replacement
–in severe cases, ciprofloxacin
•PREVENTION –public health measures, e.g., sewage disposal, chlorination, hand washing, food safety
