Analysis of the relationship between the Bacillus cereus group resistome and phenotypic antibiotic resistance
Open Access
- Author:
- Sullivan, Erin
- Area of Honors:
- Immunology and Infectious Disease
- Degree:
- Bachelor of Science
- Document Type:
- Thesis
- Thesis Supervisors:
- Jasna Kovac, Thesis Supervisor
Pamela Hankey Giblin, Thesis Honors Advisor - Keywords:
- Bacillus cereus
Bacillus
Antimicrobial resistance
Antibiotic resistance
Antibiotic resistance genes
ARGS
Broth microdilution
Whole genome sequencing - Abstract:
- Bacillus cereus group, also known as Bacillus cereus sensu lato (s.s.), is a spore-forming bacteria commonly found in the environment and food. The B. cereus group is composed of eight genomospecies which are organized into eight phylogenetic panC groups. It is known to cause foodborne illness, typically involving vomiting and diarrhea. An understanding of the relationship between resistance phenotypes and presence of antimicrobial resistance genes remains understudied. It would benefit the medical community to better recognize the correlation between the two to prescribe treatment more suitably in the interest of the patient and global community. 85 B. cereus isolates were tested for phenotypic resistance using a broth microdilution assay and interpreted with the CLSI M45 Bacillus spp. breakpoints. The broth microdilution screening revealed that there was a high prevalence of susceptibility to clinically relevant antibiotics. The broth microdilution results were then used to investigate the association between phenotypic resistance and the presence of antimicrobial resistance genes (ARG) in B. cereus group isolates. ARGs were detected in whole-genome sequences using ABRIcate and ARIBA ARG detection programs. The detected ARGs were then used to calculate sensitivity and specificity for correctly estimating the phenotypic resistance based on the presence of ARGs. ARGs with poor sensitivity and high specificity included rph (rifampicin, 0%, 93%), mph (erythromycin, 0%, 99%), bla1 (penicillin, 29%, 100), and blaZ (penicillin, 56%, 100%). Compared to penicillin, bla1 and blaZ had lower specificity for the prediction of ampicillin resistance. None of the ARGs had both high sensitivity and specificity, meaning that further study of the mechanisms underlying phenotypic antimicrobial resistance in the B. cereus group is needed.