enteric organismsa

triple sugar iron agar

TSI

lysine iron agar

LIA

motility indole ornithine agar

MIO

simmon’s citrate agar

SCA

bismuth sulfite agar

BSA

eosin metylene blue agar

EMB

salmonella shigella agar

SSA

TSI triple sugar iron agar

pH indicator is phenol red

sodium thiosulfate and ferrous sulfate
ability ferment glucose, lactose, sucrose - acid
ability to produce H2S - black precipitate
ability to produce gas - cracks and bubbles

indole test

detects typtophanase
medium: tryptone broth
reagent: KOVACS OR EHRLICH’S REAGENT

kovac’s or ehrlich’s reagent

what are the reagents used in indole test?

citrate utilization test

detects citrase
SIMMON’S CITRATE AGAR: Na Citrate, ammonium salts and ph indicator is bromthymol blue
positive: production of NaHCO3 and NH3

simmons citrate agar

what medium is used in citrate utilization test?

bromthymol blue

ph indicator of citrate utilization test

NaHCO3 and NH3

the production of _ and _ is a positive indicator of citrate utilization test

LIA lysine iron agar

detects thepresence of lysine deaminase and lysine decarboxylase, H2S
P/Y - negative for both
P/P - positive for lysine decarboxylation
R/Y - positive for lysine deamination (P, P, M)

negative for both

interpreatation of P/Y

positive for lysine deacrboxylation

P/P

positive for lysine deamination (PPM)

R/Y

MIO motility indole ornithine
SIM sulide indole motility medium

test for the motility
hazy medium

VP test

production of acetylmethylcarbinol from dextrose

e. coli
e. aerogenes
e. cloacae
k. pneumoniae

rapid lactose fermenters

edwardsiella
serratia
citrobacter

slow lactose fermenters

shigella
salmonella
proteus
providencia
morganella
yersinia

non lactose fermenters

enrethopathogenic EPEC

important caus eof diarrhea in infants

severe, watery diarrhea, vomitting and fever which are self limited but can become chronic

enterotoxigenic ETEC

common cause of traveler’s diarrhea and important cause of diarrhea for children <5 years of age

enterohemorrhagic toxin EHEC

produces the Shiga toxin or Verotoxin
mil non-bloody diarrhea in intial stages, hemorrhagic colitis, severe form of diarrhea, associated with HUS

transfusion and hemodialysis may be necessary

enteroinvasive EIEC

dss similar to shigellosis

nonlactose or late lactose fermenters and nonmotile

enteroaggregative EAEC

causes acue and chronic diarrhea

cause of foodborne illnesses in industrialized countries

associated with traveler’s diarrhea and persistent diarrhes in patients with HIV

urease test

medium is urea broth with phenol red as ph indicator
positive is dark pink medium

klebsiella pneumoniae

aka FRIEDLANDER’S BACILLUS
causes lobar pneumonia and extensive hemorrhagic necrotizing consolidation of the lung
production of currant jelly sputum
asian males

klebsiella granulomatis

formerly known as calymmatobacerium granulomatis
causes genital ulcerative disease, granuloma inguinale and is thought to be a sexually transmitted disease
TREATMENT: azithromycin

k. pneumoniae subs. ozaenae

isolated from nasla mucosa, causes atrophic rhinitis

k. pneumoniae subs. rhinoscleromatis

causes rhinoscleroma, a destructive granulomatous disease of the nasal passages but can extend to the trachea

enterobacter aerogenes and cloacae

occur in various food, hospital environment, skin and git of humans and animals

enterobacter aerogenes

produces fish eye colonies on EMB EOSIN METHYLENE BLUE AGAR

beta-lactamase, ampC

makes bacteria resistnat to ampicillin and first and second generation cephalosporins

serratia

typically transmitted form person to person, medical devices, intravenous fluids, and indwelling catheters

potassium cyanide broth

KCN

proteus
providencia
morganella

deaminates phenylalanine, motile and grown on KCN
H2S+ and urease +

proteus mirabilis

causes urinary tract infections and occasionally bloodstream infection and respiratoy tract infections
indole -

proteus vulgaris

is more implicated in wound and soft tissue infections than uti
indole +

providencia

members od normal intestinal microbiota
p. stuartii
p. rettgeri
may cause UTI

morganella

commonly found in the environment and in the intestinal tract of humans, mammals, and reptiles
frequent cause of nosocomial infections of the urinary tract and wounds
resistant to penicilline and first and second genreation cephalosporins
susceptible to broad spectrum cephalosporins, aminoglycosides, aztreonam and imipenem

citrobacter

causes UTI, spesis, RTI, intraabdominal infections, and wound infectons, principally among immunocomprimised and/or debilitated hospitalized patients
motile, h2s, and citrate +, indole -

edwardsiella tarda

can be found in the GIT of cold blooded animals

h2s+, IMVic similar to e. coli

shigella

natural habitat is the intestinal tract of humans and otehr primates causinf bacillary dysentery
micro abcesses in the wall of large intestines and terminal ileum → necrosis of mucous membrane, ulceration, bleeding and formation of “pseudomembrane”
closely realted to e. coli

shigella dysenteriae

shigella
group and type A
mannitol -
ornithine decarboxylase -

shigella flexneri

shigella
group and type B
mannitol +
ornithine decarboxylase -

shigella boydii

shigella
group and type C
manntol +
ornithine decarboxylase -

shigella sonnei

shigella
group and type D
mannitol +
ornithine decarboxylase +

shigellosis

a self limited illness
causes bloody mucoid diarrhea
bowel movement is accompanied by tenesmus, ith reslting lower abdominal pain
other sequelae includes HUS and Reiter’s chronic arthritis syndrome
type 1 (shiga bacillus) produces heat labile exotoxin

ciprofloxacin and ceftriaxone

effective antibiiotics of choice for shigella

azithromycin and antidiarrheal medications

what antibiotic is shigella resistant and what medications worsens shigella symptoms?

salmonella

caus eof enteritis, systemi infection, and enteric fever
non spore forming, most are motile with peritrichous flagella
non lactose and sucrose fermenters
utilizes lysine and citrate and usually produces h2s

salmonella typhi

most common salmonella that causes enteric fever
multiplies within peyers patches and are excreted in stools

enteric fevers

7-20 days
insidious
gradual

then high plateau with “tyohoidal” state
often early constipation

later, bloody diarrhea
positive in first to second weeks of diseae (blood culture)
positive from second week on

negativve earlier in disease (stool culture)

septicemias

variable
abrupt
rapid rise

then spiking “septic” temperature
variable
often none
positive during high fevers (blood culture)
infrequently positive (stool culture)

enterocolitis

8-48 hours
abrupt
usually lo
2-5 days
nausea, vomitting, diarrhea at onset
negative (blood culture)
positive soona fter onset (stool culture)

yersinia pestis

resevoirs are domestic cats and wild rodents

causes human plague
safety pin appearance under METHYLENE BUE or WAYSON STAIN
grows best at 25-30C

nonenteric bacteria

streptomycin

therapy of choice for yersinia pestis

alternative include TETRACYCLINE or CHLORAPHENICOL

yersinia enterocolitica

reservoirs are dogs, cats, rodents, rabbits, pigs, sheep, cattle
mot: consumption of improperly cooked food or milk products
enteroinvasive and produces heat-stable enterotoxin
medium: CIN (Cefsulodin-Irgasan-Novobiocin)
resistant to ampicillin and first generation cephalosporins

Cefsulodin-Irgasan-Novobiocin

CIN

yersinia pseudotuberculosis

rodents, rabbits, deers and birds
mot: ingestion of organism during contact with infected animal or by contaminated food and water
susceptible to ampicillin and first generation cephalosporins

pseudomona aeruginosa

not part of normal flora

causes endogenous or exogenous infections
ometimes produces a sweet or grape like odor or taco like odor
causes chronic pneumonia, malignant otitis externa

piperacillin combined with aminoglycoside (tobramycin)

treatment for pseudomona aeruginosa

vibrio

aitat is brackish or marine water

fresh → aeromonas, plesiomonas, chromobacterium
selective medium is TCBS
enrichment broth is alkaline peptone (8.4)

string test

used to differnetiate vibrio from other genus

thiosulfate citrate bile salts

TCBS

vibrio cholerae

monorichous flagella
grows best at ph 7 but can tolerate up to 9.5
ferments glucose and sucros

tetracycline or doxycycline

drug of choice for cholera

vibrio parahaemolyticus

other vibrios that cause gastroenteritis, wound infections, and bacteremia

vibrio vulfinicus

vibrio that causes fatal septicemia in patients with underlying liver dss

campylobacter

reservoirs are wild and domestic animals
curves, gram - spirillum
selctive media: Campy-CVA (cefoperazone, vancomycin and amphotericin B)
medium: Skirrow’s medium

requires atmosphere (5-7% O2 and 10% CO2)
jejuni and coli → oxidase and catalse +

campyloacter jejuni

optimal growth at 42C
hippurate hydrolysis test
gastroenteritis and systematic infections
most common cause of bacterial gastroenteritis in US
acute onset of crampy abdominal pain, profuse diarrhea that may be grossly bloody with headache, malaise and fever
susceptible to macrolides (eryhromycin)
associated with postdiarrheal GUILLAIN BARRE SYNDROME, reactive arthritis and Reiter’s syndrome

campylobacter fetus

campyloacter that causes bacteremia and extraintestinal infections

helicobacters

gram - spirillum
oxidase and urease +

helicobacter pylori

catalase and oxidase +
exotoxin allows gastric juices to digest stomach lining
asscoiated with duodenal (peptic) ulcers dss, gastric ulcers, gastric adenocarcinoma
its urease activity neutralizes the gastric acid
acute infection: food poisoning wiht nausea and pain, vomiting and feve