Study on isolation, molecular detection of virulence gene and antibiotic sensitivity pattern of Escherichia coli isolated from milk and milk products

Abstract

Aim: The study was undertaken to isolate pathogenic E. coli from milk and various milk products, detection of virulence gene using Polymerase chain reaction (PCR) and investigate their antibiotic sensitivity pattern. Materials and Methods: Altogether 250 milk and various milk products samples consisting of raw milk (50), cheese (50), ice-cream (50), mawa (50) and dahi (50) were collected from milk vendors, retail shops located in Anand city, under aseptic precautions. For the enrichment of the organism from the collected samples, MacConkey broth was used and inoculation was carried out on MacConkey agar and EMB agar. Later on, to confirm the isolates, various biochemical tests such as IMViC test, Urease test were performed. Evaluation of antibiotic sensitivity pattern of E. coli was assessed by disk diffusion method. Finally the E. coli isolates were screened for the presence of virulence associated genes by PCR. Results: The prevalence of E. coli was observed 32 % in the samples comprising of milk (52.00%), cheese (28.00%), icecream (20.00%), mawa (44.00%), and dahi (16.00%). Antibiotic sensitivity was recorded high for Co-trimoxazole (100%) followed by Gentamicin (96.73%), Trimithoprime (93.47%) and Doxycycline hydochloride (92.39%). Least sensitivity was recorded for Ampicillin (8.69%). In this study, out of 80 E. coli isolates, 25 isolates (31.25%) were positive for stx genes, of which 7 (8.75%) isolates were positive for stx1 gene only, while 12 (15.00%) isolates were positive for stx2 gene only and 5 (6.25%) isolates were positive for both stx1 and stx2, 7 isolates (8.75%) were positive for eaeA gene and all the isolate were negetive for rfb O157 gene. Conclusions: Current study supports the finding that raw milk and various milk products can be regarded as critical source of pathogenic E. coli This explains the need of strict monitoring and surveillance for effective measures of hygiene and sanitary practice during production of milk and various milk products.