2Vibrios Taxonomy Species V. cholerae Genera V. vulnificus Vibrios FamilyVibrionaciaeV. parahaemolyticus(amongst others)Non-enteric, fermentative, gram-negative rods that are oxidase positive and motile by means of a polar flagellaAeromonasPlesiomonas
3VibriosMost vibrios require saline for growth.(halophilic). However Vibrio cholerae & Vibrio mimicus can survive in both saltwater and freshwater.Prefer alkaline environments.Flourish in shallow waters with temperatures greater than 20 degrees. Ie Estuarine environments in the summer.Survive quite happily in filterfeeding shell fish, such as oysters and pipis.Greater than 90% of clinical disease due to vibrios in NZ occurs during the summer months.
4Vibrio cholerae Aetiological agent of cholera Divided into Serogroups on basis of O (somatic antigen)Only serogroups 01 and 0139 are associated with epidemic and pandemic cholera. Often clinically more serious because of production of classical cholera toxin.
5Vibrio cholerae: bacteriology Curved gram negative bacillusSingle polar flagellumFlagellar H antigen and somatic O antigen.O antigen used to classify V. cholerae into serogroups (01 and 0139 are most well known)Two biotypes of 01 (classical and El Tor)
6History of Cholera“Cholera like illness” described by Hippocrates circa 500 BCCholera means “flow of bile”The Italian doctor Filippo Pacini was the first to discover the cholera bacterium (Vibrio cholerae) in 1854 when cholera hit Florence.The first recorded cholera pandemic of spread from India to Southeast Asia, Central Asia, the Middle East and Russia.s - Seventh pandemic began in Indonesia, called El Tor. Has since spread to many countries.
10Epidemiology of Vibrio cholerae Large infective dose required. Person to person spread uncommon. Most common where poor sanitation and in particular where mass displacement of population has occuredUsually acquired through contaminated food or water. Avoidance of unboiled water, ice cubes, food from street vendors, undercooked seafood.To cause infection, organisms must first pass the highly acidic secretions in stomach. (alkaline loving) Infecting dose 10,000,000,000 orgsTherefore people with gastrectomy or on ant- acids are more susceptible orgs.Incubation period few hours to 5 days.
11Vibrio cholerae: Pathogenicity Classical cholera 01/0139 strains usually produce a classical toxin. Non 01/0139 strains usually don’tClassical Cholera toxin:- Non-invasive, consists of A and B subunits. B subunit facilitates binding and A subunit activates Adenylate Cyclase, leading to increase in cAMP in enterocyte.cAMP leads to increased Chloride excretion from the enterocyte and decreased sodium reabsorption, leading to osmotic gradient, and water passes out of the cells into the intestinal lumen. “Rice water stool”Many non-01/0139 strains are “non-toxigenic”. Actually other toxins some of which are invasive.
12It has also been hypothesized that the cystic fibrosis genetic mutation has been maintained in humans due to a selective advantage: heterozygous carriers of the mutation (who are thus not affected by cystic fibrosis) are more resistant to V. cholerae infections.
13“Cholera gravis”Most people asymptomatic or mild illness only. However shed bacteria for 1-2 wks into the environment.Severe illness, dehydration renal failure, metabolic acidosis and death.
14Diagnosis of CholeraIn epidemic “field situation”, dark field or wet film showing motile comma shaped bacteria usually sufficient. Motility inhibited by specific anti-sera.Stool can be cultured in Alkaline Peptone water to select out vibrios.TCBS (Thiosulphate Citrate Bile Salts) agar or Tellurite Taurocholate Gelatin Agar (TTGA).Yellow oxidase positive colonies are suspiciousSuspicious colonies confirmed using API20EV cholerae 01 and 0139 strains can be detected with specific anti-sera.Latex agglutination, EIA or PCR can be used to look for cholera toxin
16TCBS MediumThe high concentrations of thiosulfate and citrate and the strong alkalinity of this medium largely inhibit the growth of Enterobacteriaceae. Ox bile and cholate suppressprimarily enterococci. Any coliform bacteria, which may grow, cannot metabolizesucrose. Only a few sucrose-positive Proteus strains can grow to form yellow,vibrid-like colonies
17Treatment of CholeraAggressive rehydration is necessary for serious cases.Tetracyclines are the drug of choice. However in some parts of the world, resistance is becoming a problem. Quinolones also have good activity.In pregnant and breastfeeding women, and children, Azithromycin is useful.
18Cholera VaccineParenteral whole cell killed vaccine is available. Only 50% protection from 01 for 6 months, not recommended by WHOOral, killed, whole cell vaccine licensed for use in Europe, 1-2yrs protection after 2 doses.
19Vibrio vulnificusFirst identified in the 1970s, can cause serious wound infections and septicaemia.Usually infects patients with immunocompromise, particularly patients with underlying liver disease.V. vulnificus found commonly in saltwater estuarine environments. (Isolated from virtually all oysters harvested in the Chesapeake Bay and the United States Gulf Coast when water temperatures exceeded 20ºC)
20Vibrio vulnificus: Pathogenicity Factors Polysaccheride CapsuleAnti-capsular antibodies are protectiveIronBacterial growth in human serum is directly related to percentage transferrin saturation with iron.
21Vibrio vulnificus Infection: Acquisition Eating uncooked shellfish(especially in summer)Wading in shallow estuarine environments where patient has skin breaks to the legs.
22Risk Factors for Vibrio vulnificus septicaemia Alcoholic cirrhosis — 31 to 43 percentUnderlying liver disease including cirrhosis (unspecified etiology) and chronic hepatitis — 24 to 31 percentAlcohol abuse without documented liver disease — 12 to 27 percentHereditary hemochromatosis — 12 percentChronic diseases such as diabetes mellitus, rheumatoid arthritis, thalassemia major, chronic renal failure, "preleukemia", and lymphoma — 7 to 8 percent
23Diagnosis of Vibrio vulnificus Infection Severe clinical pictureBlue Green colonies on TCBS agarHalophilicAPI20E will give you a good idea, but other Vibrio species closely related biochemically.
24Treatment of Vibrio vulnificus Infection Should consist of a 3rd generation Cephalosporin and a TetracyclineNewer fluoroquinolones also effective.Macrolides probably are also effective.
25Vibrio parahaemolyticus : What diseases does it cause? Causes seafood associated diarrhoeal illness(usually oysters), and less commonly wound infections & septicaemia.Pathogenicity associated with production of a thermostable haemolysin (Vp-TDH) in most cases.A lot of V. parahaemolyticus bacteria don’t contain pathogenicity factors and are non-pathogenic.
26Vibrio parahaemolyticus How is it diagnosed and treated? TCBS agar. Alkaline peptone water may be used as an enrichment broth, particularly when culturing stools.Non-sucrose fermentor, therefore blue-green colonies on TCBS.API 20 E ID, ?with additional NaClClinically significant isolates will generally either be haemolytic or be urease positive.Again treatment of severe disease should involve a 3rd generation cephalosporin and oral tetracycline
27Other Vibrios Diarrhoeal Illness V. fluvialis V. mimicus V. furnissii V. HollisaeDiarrhoeal IllnessV. alginolyticusV. damselaWound Infections
28SummaryVibrios can cause serious disease. The main three are V.cholerae, V. vulnificus & V. parahaemolyticus.Appropriate plates should be set up when clinically suspected.Reasonably easy to identify to Vibrio genus level, more difficult sometimes to get the species.