title: Emergence of quinolone resistance among viridans group streptococci isolated from the oropharynx of neutropenic peripheral blood stem cell transplant patients receiving quinolone antimicrobial prophylaxis.
abstract: In neutropenic patients receiving quinolone prophylaxis, bacteremia with viridans group streptococci resistant to quinolones is a known complication. The frequency of occurrence of quinolone-resistant organisms colonizing the oropharynx during antibacterial prophylaxis with a quinolone is not well defined. In 48 patients undergoing hematopoietic stem cell transplantation, the prevalence of quinolone resistance in viridans group streptococci colonizing the oropharynx before and during antibacterial prophylaxis with gatifloxacin or moxifloxacin (most with concomitant penicillin) was determined. For quinolone-resistant isolates, mutations in the genes gyrA and parC, which confer resistance to quinolones, were analyzed. Seventy-four isolates before and 27 isolates during quinolone use were recovered from patients' oropharynxes. The numbers of susceptible isolates recovered before versus during quinolone use were as follows: 52 (70%) versus three (11%) for ciprofloxacin, 66 (89%) versus eight (30%) for levofloxacin, 66 (89%) versus ten (37%) for gatifloxacin, and 67 (91%) versus 11 (41%) for moxifloxacin (p<0.0001). Mutations in gyrA and/or parC were detected in quinolone-resistant isolates. Quinolone-resistant viridans group streptococci are frequently found in the oropharynx of neutropenic patients after a brief (median, 8 days) exposure to gatifloxacin or moxifloxacin.
authors.affiliation: Division of Infectious Diseases, Department of Internal Medicine, Mayo Clinic College of Medicine, 200 First Street SW, Rochester, MN 55905, USA.
authors.forename: R M
authors.initials: RM
authors.lastname: Prabhu
authors.forename: K E
authors.initials: KE
authors.lastname: Piper
authors.forename: M R
authors.initials: MR
authors.lastname: Litzow
authors.forename: J M
authors.initials: JM
authors.lastname: Steckelberg
authors.forename: R
authors.initials: R
authors.lastname: Patel
mesh_terms: D000328:Adult; D000368:Aged; D019072:Antibiotic Prophylaxis; D027081:DNA Gyrase / Q000235:genetics; D027101:DNA Topoisomerase IV / Q000235:genetics; D024881:Drug Resistance, Bacterial; D005260:Female; D006801:Humans; D008297:Male; D008826:Microbial Sensitivity Tests; D008875:Middle Aged; D009154:Mutation; D009503:Neutropenia; D009960:Oropharynx / Q000382:microbiology; D036102:Peripheral Blood Stem Cell Transplantation; D015363:Quinolones / Q000494:pharmacology / Q000627:therapeutic use*; D013290:Streptococcal Infections / Q000382:microbiology* / Q000517:prevention & control; D034363:Viridans Streptococci / Q000187:drug effects / Q000235:genetics / Q000302:isolation & purification*
chemical_list: D015363:Quinolones; D027101:DNA Topoisomerase IV; D027081:DNA Gyrase