Virulence and Antibiotics Susceptibility Genes in Bacillus species Isolated from Freshly Expressed Breast Milk

Breast milk can sometimes spread acute infections from bacterial and viral agents to babies. There are several recognised instances of infections caused by several microorganisms contracted through breast milk. Bacilli are Gram-positive, aerophilic, spore-producing bacteria that are ubiquitous in the environment. They are found not only in the ground, dirt, and water but also in vegetation, animals, and people. The genus Bacillus encompasses a very significant number of species as it has experienced a massive taxonomic growth with the application of 16SrRNA sequencing. This research work was focused on determining the presence of virulence genes (hblA, hblD, nheA, nheB and cesB), antibiotics resistance genes (blaVIM, vanA and vanB), endospore production, motility, biofilm formation and antimicrobial susceptibility of eighteen Bacillus species isolates (seven B. cereus, six B. subtilis, three B. licheniformis, one B. circulans and one B. brevis) obtained from freshly expressed breast milk (these isolates were predominantly isolated from mothers within the first 6 weeks of lactation).  The result obtained indicated that all the Bacillus isolates were motile, spore formers and lacked the ability to form biofilm. They were all susceptible to ciprofloxacin (100%) and resistant to ceftazidime and lincomycin (100%). All the isolates showed a distinctive band of suitable size of around 300bp for the molecular identification except isolate 12. The antibiotics resistant genes (blaVIM, vanA and vanB) were absent. Bacillus cereus possessed most of the virulence genes. nheB gene had the highest occurrence 50.0 % followed by hblA gene 33.3 %, hblD gene 16.6 %, cesB gene 5.56% while none of the isolates screened had the nheA gene.  Based on these findings, we conclude that breast milk, when not properly handled or when there is little or no observation of strict hygiene practices by the breast-feeding mother, can harbor pathogenic microorganisms such as Bacillus species which possess virulence genes as well as increase the rate of spread of antibiotics resistance from mothers to infants.