title: Quantification of Vibrio species in oysters from the Gulf of Mexico with two procedures based on MPN and PCR.
abstract: Oysters can accumulate potentially pathogenic water bacteria. The objective of this study was to compare two procedures to quantify Vibrio species present in oysters to determine the most sensitive method. We analyzed oyster samples from the Gulf of Mexico, commercialized in Mexico City. The samples were inoculated in tubes with alkaline peptone water (APW), based on three tubes and four dilutions (10-1to 10-4). From these tubes, the first quantification of Vibrio species was performed (most probable number (MPN) from tubes) and bacteria were inoculated by streaking on thiosulfate-citrate-bile salts-sucrose (TCBS) petri dishes. Colonies were isolated for a second quantification (MPN from dishes). Polymerase chain reaction (PCR) was used to determine species with specific primers: ompW for Vibrio cholerae, tlh for Vibrio parahaemolyticus, and VvhA for Vibrio vulnificus. Simultaneously, the sanitary quality of oysters was determined. The quantification of V. parahaemolyticus was significantly higher in APW tubes than in TCBS dishes. Regarding V. vulnificus counts, the differences among both approaches were not significant. In contrast, the MPNs of V. cholerae obtained from dishes were higher than from tubes. The quantification of MPNs through PCR of V. parahaemolyticus and V. vulnificus obtained from APW was sensitive and recommendable for the detection of both species. In contrast, to quantify V. cholerae, it was necessary to isolate colonies on TCBS prior PCR. Culturing in APW at 42 °C could be an alternative to avoid colony isolation. The MPNs of V. cholerae from dishes was associated with the bad sanitary quality of the samples.
authors.affiliation: Universidad Autónoma Metropolitana - Iztapalapa, México City, México. gube@xanum.uam.mx.
authors.forename: Guadalupe
authors.identifier: http://orcid.org/0000-0002-7246-3501
authors.initials: G
authors.lastname: Barrera-Escorcia
authors.affiliation: Instituto de Ciencias del Mar y Limnología, Universidad Nacional Autónoma de México, México City, México.
authors.forename: Irma
authors.initials: I
authors.lastname: Wong-Chang
authors.affiliation: Instituto de Ciencias del Mar y Limnología, Universidad Nacional Autónoma de México, México City, México.
authors.forename: Carlos Leopoldo
authors.initials: CL
authors.lastname: Fernández-Rendón
authors.affiliation: Instituto de Ciencias del Mar y Limnología, Universidad Nacional Autónoma de México, México City, México.
authors.forename: Alfonso Vázquez
authors.initials: AV
authors.lastname: Botello
authors.affiliation: Centro de Investigación en Alimentación y Desarrollo, A.C, Mazatlán, Sin, México.
authors.forename: Bruno
authors.initials: B
authors.lastname: Gómez-Gil
authors.affiliation: Centro de Investigación Científica y de Educación Superior de Ensenada, Ensenada, B.C, México.
authors.forename: Marcial Leonardo
authors.initials: ML
authors.lastname: Lizárraga-Partida
mesh_terms: D000818:Animals; D004784:Environmental Monitoring / Q000379:methods*; D060851:Gulf of America; D008800:Mexico; D010125:Ostreidae / Q000382:microbiology*; D016133:Polymerase Chain Reaction / Q000662:veterinary; D012758:Shellfish / Q000382:microbiology* / Q000592:standards; D014734:Vibrio cholerae / Q000235:genetics / Q000302:isolation & purification*; D014736:Vibrio parahaemolyticus / Q000235:genetics / Q000302:isolation & purification*; D041261:Vibrio vulnificus / Q000235:genetics / Q000302:isolation & purification*
keywords: Most probable number; Oysters’ sanitary quality; V. parahaemolyticus; V. vulnificus; Vibrio cholerae