Identification of blaVIM, blaIMP and blaSPM1 MetalloβLactamase Genes in Bacillus subtilis Strains Isolated From Raw Milk and Cheese Samples

Introduction: Studies on bacterial resistance to common antibiotics are often based on bacteria isolated from patients, with less attention towards foodborne bacteria. This study aimed to investigate the antibiotic resistance pattern and the presence of metalloβlactamase (MBL) genes viz blaVIM, blaIMP, and blaSPM1, in the Bacillus subtilis strains isolated from raw milk and cheese samples. Methods: A total of 100 raw milk and cheese samples (50 of each) were collected from the centers of production and distribution of dairy products in Ardabil city in 2017. Bacillus subtilis colonies susceptible to antibiotics were identified by conventional methods. KirbyBauer method was used to measure the antibiotic susceptibility and MBL Etest technique was used for detecting MBL enzymes. Presence of blaVIM, blaIMP, and blaSPM1 MBL genes in the bacterial strains was investigated using PCR. Results: The results showed that 25 (59.52%) isolates from raw milk samples and 16 (43.24%) isolates from cheese samples produced MBL enzyme. The MBLproducing isolates exhibited high level (100%) of antibiotic resistance, except for cefixime (67.40%) and cefotaxime (64.60%). All MBLproducing isolates expressed blaVIM gene, while blaIMP and blaSPM1 genes were not detected. Conclusion: Based on our results, molecular detection of MBL genes can be used as a complementary method along with common phenotypic diagnostic methods in the samples of dairy products, tested positive for MBL.