Vireo

Vireo

Vibrionaceae: Vireo is a genus of gram –negative bacteria possessing a curved rod shape, several species of which can cause food borne infection, usually associated with eating undercooked seafood, typically found in salt in salt water . the name vibreo derives from fillips pacing who isolated microorganisms , he called ‘’Vibrions’s from cholera patients in 1854.

Classification of vireos:

1. Vireo cholera.
2. Other vireos e.g. V. parahaemolyticus . V . fluvialis.

Vireo cholera:

Habitat         : Intestine of man.

Morphology :

Shape           : Curved comma.

Size              : 15 to 30 µm

Flagella        : Present, flagellated.

Spore           :  Absent, non-sporing.

Capsule        : Absent, non-capsulated.

Motility       : Motile,

Staining       :

They are gram negative and non-acid fast.

Cultural characters of Vireo cholera:

1. Aerobic.
2. Optimum temperature: 37°C 
3. Optimum Ph : 8-8.4
4. Growth :

ð  On Mac Conkey’s agar and DCA: Colonics are pale.

ð  On Monusr’mdeia: Colonies are dark with chacteristic hollow around them.

ð  On alkaline peptone water: vireo grows in 6 hours forming a pellicle on the surface.

ð  On gelatin stab: liquefaction occurs at the top and spreads downwards in a funnel shaped form.

Classification of Vireo cholera:

V. cholera is classified into  V, cholera ol and V, cholera non-01 serogroups or serotypes on O antigens (lipopolysaccharide).

1. V. cholera o1 are further classified into serotypes and biotypes:

a. serotypes : indaba, ogawa and Hikojima.

b. Biotypes: Classical biotype and EI Tor biotype.

2. Vibrio cholera non o1 : serogroup or serotypes 02 to 0139 have been isolated.

Biochemical behavior of Vireo cholera:

1. They ferments various sugars with acid formation but no gas.
2. It is non-lactose fermented & non-urea splitter.
3. In dole is produced and nitrate is reduced .Cholera –red reaction is positive.
4. VP reaction is negative with V. cholera (classical ) but is positive with EI Tor (biotype)

Steps;

1. Specimen collection:

-          Stool

-          Vomit.

-          Rectal swab.

2. Microscopic examination:

1. Gram staining:

Gram –negative comma shaped bacilli.

2. Hanging drop preparation: Typical motility (a fish in stream appearance).
3. Dark ground illumination (DGI) shooting star in dark sky appearance.

3. Isolation and culture:

-          Specimens inoculate in alkaline peptone water as selective and enrichment media.

-          Incubate at 37°C for overnight.

-          Streak on Mansur’s media and citrate-Bilesuctose agar (TCBS agar)

-          Characteristic colony will be appeared,

Findings:

On Mansur’s media:

ð  Small black colonies surrounded by characteristic hollows.

On TCBS agar ; Large yellow colored colony.

4. Biochemical test: Oxides-positive.
5. Serological test:

-          Slide agglutination test (mostly used)

-          Indirect haemagglutination test

-          ELISA.