Clinical Significance of Bacillus Species Other than Bacillus anthracis

Gram positive aerobic or facultatively anaerobic spore forming gram positive bacilli were first identified by Christian Gottfried Ehrenberg in 1885 and were later classified by Ferdinand Cohn in to a separate genus Bacillus [1]. Aerobic spore forming gram positive bacteria are commonly referred to as ASB’s and includes members of Bacillus spp which are basically saprophytes living as thermophiles, psychrophiles, acidophiles, alkaliphiles and halophilies exhibiting survival in versatile environmental conditions (B acidophilus, B thermophilus, B halodurans, B alcalophilus and B coagulans). There are around 260 species of the genus Bacillus, prevalent worldwide showing both molecular and physiological diversity. Among this group of bacteria, there are certain members responsible for accidental and opportunistic human infections [2,3]. Few among the Bacillus spp, infect animals that include B anthracis and B larvae, B lentimorbus, B popilliae, B sphaericus and B thuringiensis infect invertebrates (insects). Human infections with Bacillus anthracis, although is not rare, the cause of concern now is the increasing reports of human infections with other Bacillus spp like the B cereus, B subtilis and B licheniformis, B alvei, B brevis, B circulans, B coagulans, B macerans, B pumilus, B sphaericus and B thuringiensis. Bacillus spp are widely recognized for their utility as biological controls in clinical microbiology laboratories where the spores of Bacillus stearothermophilus are used to determine the efficacy of sterilization by autoclave and hot air oven. It should also be noted that there are a few antibiotics which are extracted from Bacillus spp (Bacitracin, polymixin and gramicidin were extracted from B subtilis, B polymyxa and B brevis respectively). Bacillus spp are also used to extract enzymes which can tolerate high temperatures (B thirungenesis) required for performing molecular procedures like the polymerase chain reaction (PCR). B amyloliquefaciens is another member which is used to produce natural antibiotic substance, a ribonuclease. In fact Bacillus spp have been in high demand for their medicinal, agricultural, pharmaceutical and industrial applications [4].