Lessons learned from the anaerobe survey: historical perspective and review of the most recent data (2005-2007).
BACKGROUND
The rationale and lessons learned through the evolution of the National Survey for the Susceptibility of Bacteroides fragilis Group from its initiation in 1981 through 2007 are reviewed here. The survey was conceived in 1980 to track emerging antimicrobial resistance in Bacteroides species.


METHODS
Data from the last 11 years of the survey (1997-2007), including 6574 isolates from 13 medical centers, were analyzed for in vitro antimicrobial resistance to both frequently used and newly developed anti-anaerobic agents. The minimum inhibitory concentrations of the antibiotics were determined using agar dilution in accordance with Clinical and Laboratory Standards Institute recommendations.


RESULTS
The analyses revealed that the carbapenems (imipenem, meropenem, ertapenem, and doripenem) and piperacillin-tazobactam were the most active agents against these pathogens, with resistance rates of 0.9%-2.3%. In the most recent 3 years of the survey (2005-2007), resistance to some agents was shown to depend on the species, such as ampicillin-sulbactam against Bacteroides distasonis (20.6%) and tigecycline against Bacteroides uniformis and Bacteroides eggerthii ( approximately 7%). Very high resistance rates (>50%) were noted for moxifloxacin and trovafloxacin, particularly against Bacteroides vulgatus. During that period of study, non-B. fragilis Bacteroides species had >40% resistance to clindamycin. Metronidazole-resistant Bacteroides strains were also first reported during that period.


CONCLUSIONS
In summary, resistance to antibiotics was greater among non-B. fragilis Bacteroides species than among B. fragilis and was especially greater among species with a low frequency of isolation, such as Bacteroides caccae and B. uniformis. The emergence of resistance among the non-B. fragilis Bacteroides species underscores the need for speciation of B. fragilis group isolates and for clinicians to be aware of associations between species and drug resistance.
Snydman
David R
DR
Div. of Geographic Medicine and Infectious Diseases, Tufts Medical Center, Boston, Massachusetts 02111, USA. dsnydman@tuftsmedicalcenter.org
Jacobus
Nilda V
NV
McDermott
Laura A
LA
Golan
Yoav
Y
Hecht
David W
DW
Goldstein
Ellie J C
EJ
Harrell
Lizzie
L
Jenkins
Stephen
S
Newton
Duane
D
Pierson
Carl
C
Rihs
John D
JD
Yu
Victor L
VL
Venezia
Richard
R
Finegold
Sydney M
SM
Rosenblatt
Jon E
JE
Gorbach
Sherwood L
SL
D000900:Anti-Bacterial Agents / Q000494:pharmacology*; D016470:Bacteremia / Q000382:microbiology; D001421:Bacteria, Anaerobic / Q000187:drug effects*; D001439:Bacteroides / Q000145:classification / Q000187:drug effects* / Q000302:isolation & purification; D001442:Bacteroides Infections / Q000382:microbiology; D001441:Bacteroides fragilis / Q000187:drug effects* / Q000302:isolation & purification; D003625:Data Collection; D024881:Drug Resistance, Bacterial; D006801:Humans; D008826:Microbial Sensitivity Tests
D000900:Anti-Bacterial Agents