Molecular Detection of blaTEM, blaCTX-M and blaSHV Beta-Lactamase Genes in Bacillus cereus Strains Isolated from Infant Dry Milk Samples

 Bacillus cereus is one of the important pathogen, which can be found in food samples like milk and principally responsible for food poisoning. Metallo-beta-lactamase (MBL) genes present in the Bacillus cereus bacterium, which provide resistance to the bacteria against the extreme condition. The objective of this study is to carry out molecular detection of blaTEM, blaCTX-M and blaSHV MBL genes in B. cereus strains, isolated from infant dry milk samples.  

 Total 50 samples of infant dry milk were collected from the drug store, and 19 samples were selected for this investigation. After morphological and biochemical characterization of suspected colonies which are obtained from infant dry milk samples, these isolates were confirmed for B. cereus. Antibiotic susceptibility tests were done as per criteria of Clinical and Laboratory Standards Institute (CLSI). The phenotypic confirmatory analysis was done in Mueller Hinton agar (MHA) plates with clavulanic acid. If inhibition diameter is ≥5 mm increases in the clavulanic acid (CA) containing plate than to a plate without CA, it confirmed the presence of MBL genes. PCR used for detection of MBL genes in the isolated strains.

 PCR detected the blaCTX-M (100%), blaSHV (4%) and blaTEM (84.2%) gene of B. cereus in the infant dry milk.

The study confirms that the infant dry milk is a good source of B. cereus, if dry milk has absorbed water content from the air and hence providing a perfect condition for the growth of the bacterium, so It should be kept airtight the dry milk and stored in the cold condition.