Emergence of fluoroquinolone resistance among Bacteroides species.
BACKGROUND
Several newer generation fluoroquinolones have demonstrated good in vitro activity against Bacteroides species; particularly when first introduced. However, resistance of Bacteroides to quinolones appears to be increasing.


METHODS
From 1994 to 2001, consecutive non-duplicated Bacteroides isolates from clinical specimens in 12 US hospitals were sent to the Tufts anaerobe laboratory for identification and susceptibility testing. NCCLS recommended methodology for testing was employed. Breakpoints of 8 mg/l for trovafloxacin and 4 mg/l for moxifloxacin were used to examine susceptibility trends.


RESULTS
In total, 4434 isolates were analysed. The geometric mean MIC increased significantly for clinafloxacin, trovafloxacin and moxifloxacin. Resistance to trovafloxacin (breakpoint of 8 mg/l) and moxifloxacin (breakpoint of 4 mg/l) increased from 8% to 25% and from 30% to 43%, respectively. Increased resistance was observed for all Bacteroides species, for all sites of isolation, and in 11 of 12 participating hospitals. Bacteroides vulgatus and isolates from decubitus ulcers were associated with increased resistance. During 2001, trovafloxacin and moxifloxacin resistance among blood isolates was 27% and 52%, respectively. The association between increased resistance and year of isolation remained significant after adjustment for hospital, species and site of isolation.


CONCLUSIONS
Fluoroquinolone resistance among Bacteroides isolated in the US has markedly increased during the years 1994 to 2001. High rates of resistance among blood isolates are of particular concern.
Golan
Yoav
Y
Geographic Medicine and Infectious Diseases, Tufts-New England Medical Center, Boston, MA, USA. YGolan@tufts-nemc.org
McDermott
Laura A
LA
Jacobus
Nilda V
NV
Goldstein
Ellie J C
EJ
Finegold
Sydney
S
Harrell
Lizzie J
LJ
Hecht
David W
DW
Jenkins
Stephen G
SG
Pierson
C
C
Venezia
Richard
R
Rihs
Jack
J
Iannini
Paul
P
Gorbach
Sherwood L
SL
Snydman
David R
DR
D000046:Academic Medical Centers / Q000706:statistics & numerical data / Q000639:trends*; D000890:Anti-Infective Agents / Q000494:pharmacology* / Q000627:therapeutic use; D001439:Bacteroides / Q000187:drug effects* / Q000302:isolation & purification; D003428:Cross Infection / Q000188:drug therapy / Q000382:microbiology; D024901:Drug Resistance, Multiple, Bacterial / Q000502:physiology*; D024841:Fluoroquinolones; D016015:Logistic Models; D015999:Multivariate Analysis
D000890:Anti-Infective Agents; D024841:Fluoroquinolones