Enterotoxigenic Profiles of Virulent Bacillus cereus Isolated from Dairy Environments: Antimicrobials Resistant Pattern and Sporicidal Disinfectants Efficacy

摘要

The study was aimed to characterize Bacillus cereus using culture-based and PCR techniques among 390 samples including milk, dairy products, water and environmental specimens. Antimicrobial activities of disinfectants and bioactive peptides were performed using European Suspension Test and liquid-broth method. Overall of 29.5 and 67.4% among dairy and environmental samples were positive for B. cereus. The prevalence of B. cereus in household milk, rice milk, water and street vendor milk was 37.5, 36.4, 33.3, and 30%, respectively. Moreover, the prevalence in the rinse water, used bedding material, pasture grass and pasture soil were 38.5, 37.5, 37.5 and 33.3%, respectively. HblA, hblD, hblC were detected in 42.2, 26.7, 24.4% and the nheA, nheB, nheC occurred in 31.1, 33.3, 24.4%, respectively. B. cereus isolates showed resistance to Amoxicillin, Ampicillin, Penicillin, Cephalexin and Tetracycline with 68.9, 62.2, 62.2, 57.8, and 51.1%, respectively. Hyperox and CIDEX disinfectants have extremely rapid bactericidal activity at concentrations 2 and 2.4% after five minutes of exposure times under clean condition resulting in 10.3 and 9.7 log reductions, respectively. Adding organic substances results in a marked decline of the bactericidal activity for both disinfectants. CIDEX exhibited lower Sporicidal efficacy than Hyperox under clean conditions at various exposure times/temperatures. Under the dirty condition, Cidex showed similar or slightly higher sporicidal activity than Hyperox. At 4 hrs/ 20 & 40 oC under dirty conditions, 4.8, 5.6 and 4.6, 5.2 log reductions for CIDEX and Hyperox, respectively were observed. P-CWP and P-CCP showed effective antimicrobial action resulting in 10 and 8 log reductions at a concentration of 2 mg/ml, respectively against B. cereus. However, CCP and CWP exhibited little to moderate antimicrobial activity. The prevalence of Eneterotoxigenic virulent B. cereus and their drug resistance profiles diversity suggest that the examined dairy environments in villages of Sohag governorates, Egypt poses animal and public health threats.