CLIN BACTE MODULE 5 (Motility test - )

MOTILITY TEST use

Very useful in detecting non-motile enterics Klebsiella & Shigella

MOTILITY TEST media

SIM media

MOTILITY TEST On a tube media, it is motile

growth is outside the line of streak

MOTILITY TEST On a tube media, it is NM

growth is @ the line of streak

MOTILITY TEST dye

TTC-triphenyl tetrazolium chloride – colorless dye that turns red with organisms’ growth

MALONATE UTILIZATION TEST

Based on the ability of the organism to use sodium malonate as the only carbon source

MALONATE UTILIZATION TEST Indicator

Bromthymol Blue

MALONATE UTILIZATION TEST (+) result

blue color

MALONATE UTILIZATION TEST (-) result

green color

motility of salmonella

motile

motility of shigella

NM

TEST TO DETECT H2S PRODUCTION media

May be carried using any media provided that the media contains an indicator for H2S detection

Examples of media with H2S indicator:

TSI, LIA, SIM, HEA

• H2S indicator in HEA, SSA and LIA

Ferric Ammonium Citrate

MOST SENSITIVE MEDIA FOR H2S

SIM

H2S POSITIVE:

• Salmonella;

• Edwardsiella tarda,

• Citrobacter freundii;

• Proteus vulgaris

• Proteus mirabilis

DECARBOXYLASE TEST

Based on the ability of the organism to remove carboxyl group from specific amino acid thru the release of the enzyme decarboxylase

DECARBOXYLASE TEST amino acids

• LYSINE

• ORNITHINE

• ARGININE

• LYSINE removes

CADAVERINE

• ORNITHINE removes

CADAVERINE

ARGININE removes

CITRULLINE

DECARBOXYLASE TEST media

Moeller’s Broth/LIA

DECARBOXYLASE TEST indicator

bromcresol purple/cresol red

Moellers contain:

• glucose: CHO

• pH indicator: bromcresol purple/bromcresol red

• Amino acids

• Mineral oil (oxygen barrier; make rx anaerobic(

• (+) purple

• (-) yellow

LIA

• It is a media dispensed as slant & butt

• Contains Glucose & Lysine

• pH indicator:bromcresol purple/cresol red

• H2S indicator : ferric ammonium citrate

• SLANT is observed for

DEAMINATION

BUTT is observed for

DECARBOXYLASE TEST

DECARBOXYLASE TEST (-)

green

DECARBOXYLASE TEST (+)

purple

DEAMINATION (+)

burgundy

DEAMINATION (-)

purple

K/K H2S (+) Purple/Purple rx

(-) Deaminase (+) Decarboxylase

K/K H2S (+) Purple/Purple organism

salmonella

K/A H2S (-) Purple/Yellow

(-) Deaminase (-) Decarboxylase

K/A H2S (-) Purple/Yellow organism

shigella

R/A H2S (-) Red Yellow

(+) Deaminase (+) Decarboxylase

R/A H2S (-) Red Yellow organism

PPM

PROTEUS -PROVIDENCIA-MORGANELLA

• Biochemically similar; rapid urease producers & deaminase (+)

• Non-lactose fermenters (TSI), K/A

• rapid lactose (+)

Proteus mirabilis

Most frequently isolated may cause pneumonia & septicemia

Proteus vulgaris

Causes nosocomial UTI

GENUS PROTEUS

use as source of antigens used in Weil Felix Test

Facultative Anaerobe

Proteus vulgaris source of

OX2,OX19

Proteus mirabilis source of

OXK

What genus detect rickettsial infx

Genus proteus

GENUS PROTEUS Colonies on Mac Conkey agar with

burnt chocolate/burnt gun powder odor

GENUS PROTEUS

Shows SWARMING on BAP

GENUS PROVIDENCIA

• No swarming on BAP

• Normal intestinal flora

• Species: P. rettgeri & P. stuartii

GENUS MORGANELLA

• Species: Morganella morganii

• Can cause UTI’s & RTIs

GENUS YERSINIA

Motile at room temperature but non-motile at 37 degC except Yersinia pestis

Yersinia pestis

• Causative agent of PLAGUE

• A bioterrorism agent

Yersinia pestis

• Assumes a safety pin appearance because of Bipolar staining (only both ends are stained) which can be demonstrated using Wayson stain/Methylene Blue

Yersinia pestis

• On liquid media/ broth it produces stalactite growth (clumps/sides of tube)

Yersinia pestis

• On BAP it can develop Hammered copper colonies (prolonged incubation)

Yersinia enterocolitica

A late lactose fermenter

Yersinia enterocolitica

Can cause enterocolitis in which symptoms may be mistaken for appendicitis (pseudoapendicular syndrome)

Yersinia enterocolitica Can tolerate cold enrichment

4 degree for 2 weeks

Yersinia enterocolitica

Can produce Bull’s eye( pink col w/ red centers) colonies on CIN media w/ neutral red

Yersinia pseudotuberculosis

Agent of mesenteric lymphadenitis

SALMONELLA- SHIGELLA

• Intestinal pathogens

• Spread via fecal oral route

GENUS SHIGELLA

• Can cause shigellosis/bacillary dysentery

• Species are invasive and can produce endotoxin

S. dysenteriae

can produce endotoxin & neurotoxin

GENUS SALMONELLA

• Species can cause a number of infections

• Site of long-term carriage of S. typhi is the gall bladder

GENUS SALMONELLA Selective media

Bismuth Sulfite Agar

Bismuth Sulfite Agar

Black colonies with metallic sheen

GENUS SALMONELLA Species

• Salmonella enterica

• Salmonella bongori (animal pathogen)

Bacteremia Serotypes

S. cholerasuis

Enterocolitis/Gastroenteritis Serotypes

S. typhimurium

Enteric fever Serotypes

• S. enterica serotype typhi

• S. paratyphi A

• S. paratyphi B

• S. cholerasuis

GENUS ENTEROBACTER

Members of this genus are normal intestinal flora but may cause opportunistic infections

GENUS ENTEROBACTER Most predominant isolate is

E. cloacae

• E. sakasakii is now Cronobacter sakasakii - This is known to produce

pigment that intensifies at room temperature

GENUS ENTEROBACTER

Can cause necrotizing colitis often due to powdered infant milk formula

GENUS KLEBSIELLA

Significant species is Klebsiella pneumoniae

Klebsiella pneumoniae

• • Also known as Friedlander’s Bacillus

• • Can cause community acquired pneumonia (currant jelly like sputum)

• • (+) encapsulated -Neufeld Quellung Positive

• • On plated media it can develop MUCOID COLONIES

• • (+) String test – positive result is due to the mucoid colonies •

K.oxytoca

biochemically resembles K. pneumoniae but can be differentiated from the latter for its being indole (+)

• K. ozaenae

can cause perulent sinus infx.

• K. rhinoscleromatis

– granuloma of the nose and nasopharynx

Escherichia coli

a.k.a Colon Bacillus

• # 1 cause of community acquired UTI

Escherichia coli • Virulence Factors:

• PILI (common)

• Cytolysins (inhibit immune effector cells)

• Aerobactin(chelate iron)

Escherichia coli

Normal GIT flora so found in normal stools. Use as the primary marker of fecal contamination

Escherichia coli IMViC reaction is

++--

Nephropathogenic E. coli / Uropathogenic E. coli

serotype that causes UTI

Diarrheagenic/Enterovirulent E. coli

– these are the serotypes known to cause diarrhea

ENTEROTOXIGENIC E. COLI ETEC

Can cause PROFUSE/SEVERE watery diarrhea that is CHOLERA LIKE due to production of toxin ENTEROINVASIVE

E. COLI EIEC

Can cause bloody diarrhea that is Shigella like due to its ability to invade the bowel mucosea

ENTEROPATHOGENIC E. COLI EPEC

Non-toxigenic and non-invasive but can cause diarrhea in infants / infantile diarrhea

ENTEROAGGREGATIVE E. COLI EAEC

Can cause acute & persistent diarrhea in children and adults

DIFFUSELY ADHERENT E. COLI DAEC

This constitutes the 6th group in the diarrheagenic E. coli.

Can cause diarrhea in otherwise healthy patrients

ENTEROHEMORRHAGIC E. COLI VEROTOXIC E. COLI SHIGA TOXIN PRODUCING

• Can cause SEVERE BLOOD DIARRHEA due to its ability to produce VEROTOXIN

• HUS -hemolytic uremic syndrome,

• Most severe manifestation of EHEC Specific example is E. coli 0157:H7

ll E. coli serotypes are LF on Mac Conkey agar, all can develop.

pink purple

To detect EHEC/E. coli 0157:H7 we use

• SORBITOL MAC CONKEY AGAR /SMAC.

• This is like the usual Mac Conkey agar but instead of Lactose it contains SORBITOL. Inhibitor & indicator same as the usual Mac Conkey.

• Only Lactose was replaced

In Sorbitol Mac Conkey (SMAC)- Sorbitol (+) can develo

pink-purple colonies

In Sorbitol Mac Conkey (SMAC)- Sorbitol (-) can develo

colorless

All E. coli serotypes can develop pink-purple colonies on SMAC except

E. coli 0157:H7 (Mug test -)

Mug test

• 4 methyl umbelly feryll - b - d- glucoronide

• detect enzyme beta-D-glucoronidase

Mug test (+)

Electric blue fluorescence (UV)

Genus that resembles Salmonella but is ONPG (+) and LDC (-)

Genus Citrobacter

Citrobacter species documented as a cause of outbreak of neonatal meningitis

C. koseri

Red Pigment produced by Serratia marcescens

PRODIGIOSIN