ISOLATION AND CHARACTERIZATION OF AEROMONAS SPECIES FROM FISH
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Date
2009
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AAU, Anand
Abstract
The present study was undertaken with the objective to isolate and characterize the Aeromonas spp. from raw fish intended for the human consumption available in the retail fish market in Anand, Gujarat. A total of 100 raw fish samples (muscles) were collected from the fish market. Samples were processed with pre-enriched in alkaline peptone water (pH 8.4 ± 0.2) at 37°C for 24 h and further inoculated on three selective media viz., Ampicillin starch DNA agar (SAA), Ampicillin dextrin agar (ADA) and Aeromonas isolation agar (ALA). The presumptive isolates were identified at genus and species level by the battery of biochemical tests and also confirmed by polymerase chain reaction. The PCR confirmed isolates were further subjected for the antibiotic susceptibility test using fourteen antibiotics and detection of virulence genes by PCR. In the present study, out of 100 raw fish samples 47 were found to be contaminated with three pathogenic species. From these 47, a total of 61 Aeromonas isolates comprising of 52 (85.2 %) A. sobria, 5 (8.2 %) A. hydrophila and 4 (6.6 %) A. caviae were isolated. The present findings also revealed the superiority of Ampicillin dextrin agar (ADA) over Ampicillin starch DNA agar (SAA) and Aeromonas isolation agar (AIA). ADA recovered 43 (70.5%) isolates as compared to 10 (16.4%) and 8 (13.1%) isolates recovered on SAA and AIA respectively. All the Aeromonas isolates were resistant to ampicillin and bacitracin and cent percent sensitive to ciprofloxacin and chloramphenicol. The isolates were found to be commonly resistant to oxytetracyclin, streptomycin, kanamycin, tetracycline, rifampicin, erythromycin, carbenicillin, gentamicin, cephalothin and chlortetracycline. The isolates were also found to be resistant to multiple drugs varying from two to nine drugs. All isolates were also subjected for the in vitro detection of virulence gene viz., aerolysin, hemolysin and enterotoxin by PCR using specific primers. The result indicated that out of 61 isolates, a total of 21 isolates were found to harbor different combination of virulence genes. Seventeen (27.9%), 8 (13.1%) and 8 (13.1%) isolates were positive for enterotoxin, aerolysin, and hemolysin respectively. Owing to the potential hazard of pathogenic Aeromonas spp., it was concluded that it is necessary to put more emphasis on food hygiene. Therefore, the surveillance of potential contaminant is crucial for sustenance of public health.
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Keywords
VETERINARY PUBLIC HEALTH, CHARACTERIZATION