Susceptibility and Identification of Bacillus cereus on Chromogenic Selective Agar Isolated from Hospital Environments

Background: Bacillus (B.) cereus is widely distributed in different environments including hospitals and health centers that considered one of the highly resistant organisms to various antimicrobial agents.This investigation aimed to detect the incidence of B. cereus in hospital environments and their antibiotic susceptibility profile.Materials and methods: A total of 114 swaps were collected from different places in the hospital and divided into two groups, floors 56 (49%) and equipment 58 (51%).Swabs cultured on blood agar, bacteria were identified according to the morphological characteristics and microscopic examination that confirmed by Bacillus ChromoSelect Agar.The antibiotics susceptibility test was carried out by following the Kirby Bauer method by using 7 antibiotics from various classes.Results: From 114 specimens, 48 (42%) were positive for B. cereus.Antibiotic sensitivity test revealed highest resistance for ampicillin 33/48 (68.8%), cephalexin 31/48 (64.6%), and imipenem 25/48 (52.1%), and highest sensitive for ciprofloxacin 42/48 (87.5%) and gentamycin 40/48 (83.3%).The high positive correlation between cephalexin and ampicillin (r = 0.78, p = 0.001), tetracycline and ciprofloxacin (r = 0.64, p = 0.001), and no correlation between cephalexin and gentamycin (r = -0.063,p = 0.67). Conclusion:This study revealed a high prevalence of B. cereus in hospital floors and equipment with high resistance to various antibiotics including β-lactams and tetracycline.The monitoring of hospital environments is an important tool in the prevention of hospital-associated infection by B. cereus.