Isolation of soil Bacillus spp with inhibitory activity against methicillin-resistant Staphylococcus aureus (MRSA)

The overuse of antibiotics in both human medicine and agriculture has contributed greatly to the crisis we experience today. In the United States alone, at least 2 million people acquire resistant infections with approximately 23,000 of these cases resulting in death each year. MRSA infection, in otherwise healthy individuals, affects the superficial skin and soft tissues, though more serious infections can arise, affecting the deep soft tissues, blood, and bone. MRSA is able to avoid the body’s immune system through production of biofilm as well as certain toxins. These virulence factors, in combination with multidrug resistance, result in high morbidity and mortality rates. One of the first studies, published in 1904, to detail the effect of soil organisms on pathogens reported the inhibition and death of pathogens as a result of saprophytes. Several soil organisms found to have inhibitory effects on a range of pathogens have since been reported. The most common antagonistic soil organisms can be divided into four major genera, including the spore-forming genus, Bacillus. A protocol for the isolation of soil Bacillus spp was followed after which the samples were screened against a methicillin-sensitive strain of S. aureus. Those isolates producing zones of inhibition were selected for purification. These pure cultures were then tested against a resistant strain. The most promising isolates were identified by 16S rRNA sequencing. Spent media analysis is currently in progress