Vibrio cholerae Culture & Diagnosis

TCBS medium- Thiosulfate, Citrate, Bile salt & Sucrose [Ref Anantnarayan Micro, 7^th/e p 305-306] Repeat _.from May 2008

Ans. is ‘b’ i.e., Transported in alkaline peptone water medium

Ans. is ‘b’ i.e., Cary Blair medium 

Ans. is ‘c’ i.e., Has marked tolerance of alkaline pH 

Ans. is ‘b’ i.e., Cary Blair medium 

Ans. is ‘a’ i.e., VR medium 

Ans. is ‘d’ i.e., All of the above

Quarantinable diseases

o Diphtheria                       o Yellow fever                       o Infectious TB                                    o SARS

o Plague                            o Small pox                          o Viral hemorrhagic fever

Also Know :

• Quarantine was first applied for plague.
• Quarantine period for yellow fever is 6 days.
• Quarantine has been ‘replaced by active surveillance’.

Ans. C: Vibrio cholerae

• Modified Cary and Blair medium is recommended as a good transport medium. It is a very stable medium and can be stored for use in screw capped containers. It is a semi-solid transport medium. At least two swabs should be inoculated.
• Alternative transport media for vibrio cholera are Venkataraman-Ramakrishnan medium (V-R fluid) or alkaline peptone water.VR fluid should be prepared in 30 ml (1 oz) screw capped bottles (MacCartney bottles). It preserves vibrios for more than 6 weeks and has also proved to be very convenient medium for transportation as it can be kept at room temperature after collection of specimen.
• If none of the transport medium is available, collect watery stool from suspected cholera case by soaking blotting paper strip in the stool, sealing the strip in a polythene bag or an airtight container where the strip does not dry. The moist blotting paper strip can then be transported to the laboratory. Blotting papers have been found to be superior to the filter paper as the former can soak more moisture and retain the same over longer periods thus maintaining the viability of vibrios absorbed on it.

Ans. is ‘d’ i.e., Alkaline peptone water

Alkaline Peptone Water (CM1028) is for the enrichment of Vibrio cholera and Vibrio species from food, water and clinical samples. This broth can also be used for direct microscopic examination of samples using the hanging drop method.

Alkaline Peptone Water was first formulated by Shread, Donovan and Lee– to be used as a non-selective enrichment broth for the cultivation of Aeromonas spp. Cruickshank reported that when the pH is raised, the medium can be used to effectively cultivate Vibrio species.

The 2% (w/v) sodium chloride incorporated in this medium promotes the growth of Vibrio cholerae, while the alkalinity of this medium inhibits most of the unwanted background flora.

Ans. is ‘a’ i.e., 1%

V. cholerae is not nutritionally fastidious and grows well on ordinary media.

Optimum temperature for growth is 37°C (range 16-40°C).

They grow better in alkaline media with oPtimum pH 8.2.

0.5-6% NaCl is required for optimal growth (6% or above NaCl inhibits the growth)  

Ans. is ‘d’ i.e., Campylobacter – BCYE medium

• Campylobacter infection is diagnosed when a laboratory test detects Campylobacter bacteria in the stool (poop), body tissue, or fluids. 

• The test could be a culture that isolates the bacteria or a rapid diagnostic test that detects the genetic material of the bacteria.

• Skirrow medium, Campy BAP medium, Butler’s media used for Campylobacter

• A comparison of Skirrow’s, Butzler’s, Blaser’s, Campy-BAP and Preston media for Campylobacter spp was made using human, animal and environmental specimens. 

• Butzler’s medium gave the lowest insolation rate and Preston medium, which was the most selective, the highest isolation rate. Enrichment culture using Preston enrichment broth gave a higher isolation rate than direct plating onto Preston medium.

Ans. is ‘a’ i.e., GTTA medium

Selective (plating) media for vibrio cholera are Thiosulfate-citrate-bile salts-sucrose agar (TCBS) medium, Monsur’s gelatin taurocholate trypticase tellurite agar (GTTA) medium and Alkaline bile salt agar not mannitol‐yolk‐polymyxin B agar (MYPA) media.

Enrichment Media

1. Alkaline peptone water at pH 8.6
2. Monsur’s taurocholate tellurite peptone water at pH 9.2

Plating Media

1. Alkaline bile salt agar: The colonies are very similar to those on Nutrient Agar.
2. Monsur’s gelatin Tauro cholate trypticase tellurite agar (GTTA) medium: Cholera vibrios produce small translucent colonies with a greyish black centre.
3. TCBS medium: This the most widely used medium. This medium contains thiosulphate, citrate, bile salts and sucrose. Also in oysters and lobster in some cases. Cholera vibrios produce flat 2-3 mm in diameter, yellow nucleated colonies. 

Holding or Transport Media 

1. Cary-Blair medium: This the most popular carrying media. This is a buffered solution of sodium chloride, sodium thioglycollate, disodium phosphate and calcium chloride at pH 8.4.
2. Venkataraman-ramakrishnan (VR) medium

Ans. is ‘c’ i.e., 5 days