Prevalence, PFGE Typing, and Antibiotic Resistance of [i]Bacillus cereus[/i] Group Isolated from Food in Morocco
Résumé
This article reports the prevalence and antibiotic resistance of the Bacillus cereus group isolated from different
foods (milk and dairy products, spices, and rice salad) in Morocco. In total, 402 different food samples collected
from 2008 to 2010 were analyzed by microbiological methods to isolate B. cereus. The strains were subjected to a
polymerase chain reaction test in order to verify whether they belonged to the B. cereus group. Sixty-four of all
isolates (15.9%) were found to be positive. Among the sources, B. cereus strains from milk and dairy products
constituted the largest proportion of isolates (33/64; 51.6%) followed by spices (22/64; 34.4%) and salad with rice
(9/64; 14.1%). The genetic diversity of the strains of B. cereus group was examined by pulsed-field gel electrophoresis
(PFGE) of chromosomal DNA digested with SmaI. The enzyme restriction profiles showed a high
degree of polymorphism among the strains. The results showed that PFGE analysis could reveal the genetic
differences among B. cereus strains. Investigation of antibiotic-resistance profiles showed that isolates were
resistant to ampicillin (98.4%), tetracycline (90.6%), oxacillin (100%), cefepime (100%), and penicillin (100%), and
were susceptible to chloramphenicol (67.2%), erythromycin (84.4%), and gentamicin (100%). The results of this
study indicated that B. cereus could be a significant etiological agent of food poisoning in Morocco because of its
high prevalence. Also, we demonstrated that the majority of strains came from milk and dairy products.
However, additional research involving cytotoxicity tests is needed to more evaluate this sanitary risk.