Virulence genes and antibiotic resistance profile of Vibrio species isolated from fish in Egypt

Vibrio species are significant pathogens affecting aquatic species. Around 12 species of Vibrio can cause a gastrointestinal illness (gastroenteritis) in humans resulting from eating contaminated food such as raw or undercooked shellfish. The indiscriminate use of antibiotics accelerates the development of resistance representing a severe challenge for controlling Vibrio outbreaks. In this study, the antibiotic resistance profile and the prevalence of pathogenic Vibrio species of apparently healthy and diseased fishes isolated from different types of fish in Kafr EL-Sheikh Governorate in Egypt during 2018 were determined. Samples obtained from fishes were inoculated onto a Vibrio-selective medium (TCBS) and phenotypically identified using the biochemical characteristics and representative cultures were checked by PCR to confirm the identified isolates. In the present study, V. alginolyticus (16.00%) was the predominant species followed by V. cholerae (7.33%) and V. parahaemolyticus (5.33%). The tested isolates were resistant to ampicillin (80.00%) and sensitive to ciprofloxacin and norfloxacin (100%). A total number of 15 Vibrio isolates (5 Vibrio parahaemolyticus, 5 V. alginolyticus, and 5 V. cholerae) were screened for five housekeeping genes and pathogenic virulence markers by PCR. Results showed that 100% of the V. parahaemolyticus isolates carried the tlh gene and 60.00% carried the tdh gene. In V. alginolyticus, 100% of the isolates carried the collagenase gene 0.00% carry the tdh gene; and 80.00% of V. cholerae isolates carried the ctx gene. The results showed that many isolates in this study had virulence characteristics that might correspond with the potential of infections and diseases.