Prevalence of enterotoxin genes and antibacterial susceptibility pattern of pathogenic bacteria isolated from traditionally preserved fish products of Sikkim, India

Abstract

Suka ko maacha, sidra and sukuti are traditionally preserved fish products of Sikkim in India. The present study was aimed to assess the microbiological quality of traditionally preserved fish products by identifying the potential pathogenic bacteria, detecting the enterotoxins, and screening the antibiotic susceptibility patterns. The pH and moisture contents of fish products were 6.5–7.1 and 7.2–15.0%, respectively. The microbial load of aerobic bacteria was 105 to 107 cfu/g, Staphylococcus count was 105 to 106 cfu/g, Bacillus count was 104 to 106 cfu/g and total coliform count was 105 to 107 cfu/g, respectively. Based on the 16S rRNA gene sequence analysis, bacterial species isolated from traditionally preserved fish products were Bacillus cereus, Salmonella enterica, Staphylococcus sciuri, Staphylococcus aureus, Staphylococcus edaphicus, Staphylococcus nepalensis, Staphylococcus vitulinus, Enterobacter hormaechei, Enterobacter cloacae, Klebsiella pneumonia, Escherichia coli, Escherichia fergusonii, Providencia vermicola, Providencia stuartii, Providencia rettgeri, Enterobacter cancerogenus, Acinetobacter radioresistens and Pseudomonas plecoglossicida. The ELISA tests detected enterotoxins produced by Bacillus cereus and Staphylococcus in few samples. Bacillus cereus and Staphylococcus enterotoxin genes were detected in few samples by PCR method. More than 90% of antibiotic sensitivity pattern was shown towards gentamicin, norfloxacin, streptomycin, ciprofloxacin, tobramycin, and trimethoprim. The highest rate of resistant pattern was observed towards amoxicillin-clavulanate (53%) followed by nitrofurantoin (45%), ampicillin (37%), aztreonam (30%), and cefoxitin (26%).