TITLE:
Bacillus cereus Group Exhibits More Resistant to Chlorhexidine Rather Than Bacillus subtilis Group
AUTHORS:
Akira Okamoto, Saki Otsuji, Miho Kamako, Ikumi Inoue, Kokoro Tasaka, Juntaro Kato
KEYWORDS:
Bacillus cereus, Bacillus subtilis, Chlorhexidine, Susceptibility
JOURNAL NAME:
Open Journal of Medical Microbiology,
Vol.10 No.3,
August
24,
2020
ABSTRACT: Chlorhexidine is a widely used antiseptic agent; however, its
bactericidal effect against bacterial endospores is limited. The genus Bacillus is spore-forming gram-positive bacteria that are ubiquitously found in the environment
and cause opportunistic infection and food poisoning. The susceptibility of
bacterial endospores to chlorhexidine was previously evaluated in Bacillus subtilis, but the primary
target for disinfection with antiseptic agents, including chlorhexidine, should
be harmful strains. We aimed to evaluate the susceptibility of harmful cereus group including Bacillus cereus,
and to compare that with harmless Bacillus species, containing B. subtilis. We evaluated the
susceptibility of the 15 strains of the cereus group to chlorhexidine
in comparison with the 5 other strains, named the subtilis group in this
study. Our results indicated that chlorhexidine exerted a bacteriostatic effect
against Bacillus species at practical concentrations, especially during
long-term exposure. The strains of B. cereus group in this study displayed
relatively lower susceptibility to the antiseptic than the B. subtilis group
according to the minimum inhibitory and bactericidal concentrations. We
concluded that there are intrinsic differences in the susceptibility to
chlorhexidine between the groups, but the molecular mechanisms are unknown. The
minimum inhibitory or bactericidal concentrations of disinfectants other than
chlorhexidine may also need to be clarified in the B. cereus and B. subtilis groups.