Genotypic and phenotypic analysis of Clostridium difficile correlated with previous antibiotic exposure.
To analyze Clostridium difficile susceptibility results and genotypes in relation to antibiotic exposures that precipitated C. difficile-associated diarrhea (CDAD), we examined 83 nosocomial C. difficile isolates recovered at a tertiary care center in Boston, Massachusetts. MICs were determined by E-test methodology using modified Brucella agar. Isolates were genotyped by pulsed-field gel electrophoresis and restriction enzyme analysis. Antibiotic susceptibilities were: ciprofloxacin (0%), clindamycin (59%), trovafloxacin (63%), ceftriaxone (73%), piperacillin/tazobactam (100%), metronidazole (100%), and vancomycin (100%). The two most common strain groups, isolated from a total of 33 patients, were much more likely to be resistant to clindamycin, erythromycin, and trovafloxacin than other strain groups [79% (26 of 33) versus 2% (1 of 50), respectively]. Clindamycin exposure was strongly associated with CDAD caused by isolates that exhibited multiple resistance to clindamycin, erythromycin, and trovafloxacin (prevalence odds ratio, 4.2; 95% confidence interval, 1.1-16.8), whereas other antimicrobials did not yield significant associations. Resistance of specific C. difficile strains to clindamycin and other antimicrobial agents may contribute to their hospital dissemination and explain, in part, the propensity of clindamycin to trigger nosocomial outbreaks.
VA Salt Lake City Health Care System, and Division of Clinical Epidemiology, Department of Internal Medicine, University of Utah School of Medicine, Salt Lake City, UT 84132, USA. Matthew.Samore@hsc.utah.edu
Matthew H
MH
Samore
Lata
L
Venkataraman
Paola C
PC
DeGirolami
Michelle M
MM
Merrigan
Stuart
S
Johnson
Dale N
DN
Gerding
Yehuda
Y
Carmeli
Stephan
S
Harbarth
D000328:Adult; D000368:Aged; D000900:Anti-Bacterial Agents / Q000494:pharmacology*; D002981:Clindamycin / Q000494:pharmacology; D016360:Clostridioides difficile / Q000145:classification / Q000187:drug effects* / Q000235:genetics; D024881:Drug Resistance, Bacterial; D005260:Female; D005838:Genotype; D006801:Humans; D008297:Male; D008826:Microbial Sensitivity Tests; D008875:Middle Aged; D010641:Phenotype
D000900:Anti-Bacterial Agents; D002981:Clindamycin