Halophilic vibrios

Halophilic vibrios, Vivrio haemolyticus, Vibrio Parahaemolyticus, vibrio vulnificus

1. HALOPHILIC VIBRIOS Dr Vishal Kulkarni MBBS MD (Microbiology)

2. Definition Vibrios that need high concentration of NaCl and can not grow in absence of it are called halophilic vibrios Natural Habitat- Sea water Marine life

3. Some of halophilic vibrios have been known to cause human disease V. parahaemolyticus V. alginolyticus V. vulnificus

4. Vibrio parahaemolyticus Enteropathogenic vibrio isolated in Japan in 1951 Occurred as a outbreak of food poisoning caused by sea fish Gastroenteritis has been reported from several countries. Inhabits in costal areas. Fish, arthropods, shrimps, crabs, molluscs Kolkata - small pond fish.

5. Morphology- Gram negative bacilli Short, comma shaped, motile Fish in stream appearance Capsulated Shows bipolar staining Pleomorphism Peritrichous flagella on solid media Polar flagella formed in liquid culture

6. Cultural characteristics- Grows on media containing NaCl Can tolerate conc. u p to 8 % (but not 10%) Optimum conc.- 2-4% On TCBS- colonies are green with opaque, raised center and flat translucent periphery String test is positive

7. Biochemical characteristics- Oxidase , catalase , nitrate, indole and citrate positive. Glucose, maltose, mannitol, mannose and arabinose are fermented with producing acid only. 3 antigens- O, K and H Serotyping is based on O & K Ag.

8. Resistance- Killed at 60˚C in 15 minutes. Drying destroys it Does not grows at 4˚C but can survive refrigeration and freezing. Dies in distilled water & vinegar in few minutes.

9. Pathogenicity - All strains are not pathogenic Kanagawa phenomenon- When grown on high salt blood agar, produce haemolysis Strains from human patients are almost always haemolytic No enterotoxin is produced Causes enteritis due to invasion of intestinal epithelial cells.

10. Clinical features- Food poisoning associated with marine food. Acute diarrhea, abdominal pain, vomiting, fever Feces generally contain cellular exudate often also blood. Dehydration is of moderate degree. Recovery- within 1-3 days.

11. Epidemiological features- Cases are common in adults than in children. Occurs mostly in summer . In Kolkata, V. parahaemolyticus could be isolated from 5-10% of diarrheal cases.

12. Lab diagnosis- Microscopy - dark ground/ Phase contrast, IF Culture - NA, BA,Mac Conkey TCBS- Green colonies ( sucrose non fermentation) Wagatsuma agar- Kanagawa phenomenon Biochemical reactions Catalase , oxidase - positive Nitrate, indole , citrate- positive Ferments - glu , malt, mannitol, mannose, arabinose with acid - String test positive

13. V. alginolyticus Morphology- Resembles V.parahaemolyticus in many respects. Can tolerate higher salt concentration (10%) Has been associated with infections of the eyes, ears, wounds in human beings exposed to sea water.

14. Tests V. Parahaemolyticus V. alginolyticus Indole + + VP - + Nitrate reduction + + Urease - - Sucrose fermentation - + Swarming - + Growth on 0% NaCl - - 7 % NaCl + + 10 % NaCl - +

15. Vibrio vulnificus Previously known as L+ vibrios or Beneckea vulnifica Marine vibrio Morphology- resembles V. parahaemolyticus . Biochemicals and cultural characteristics- VP negative. F erments lactose but not sucrose Can tolerate up to 8% NaCl .

16. Clinical features- Two types of infections- 1. Wound infection (contact with sea water) 2. Septicemia in person with pre-existing hepatic disease following consumption of raw oysters. Penetrate gut mucosa without GI manifestations and then blood stream leading to septicemia High Mortality

17. Other clinically important spp. V. damsela V. fluvialis V. furnisii V. hollisae V. metschnikovii V. mimicus