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Infectious Diseases in Obstetrics and Gynecology
Volume 2007, Article ID 46581, 6 pages
Research Article

Rapid Determination of Macrolide and Lincosamide Resistance in Group B Streptococcus Isolated from Vaginal-Rectal Swabs

1Clinical Investigation Facility, David Grant USAF Medical Center, Travis Air Force Base, CA 94535, USA
2Department of Pediatrics, F. Edward Hébert School of Medicine, The Uniformed Services University of the Health Sciences, Bethesda, MD 20814-4799, USA
3Medical Laboratory Flight/Microbiology Department, David Grant USAF Medical Center, Travis Air Force Base, CA 94535, USA
4Department of Infectious Diseases, Eglin USAF Regional Hospital, Eglin Air Force Base, FL 32542-1282, USA

Received 23 January 2007; Accepted 16 April 2007

Copyright © 2007 Wilfred P. Dela Cruz et al. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.


Objective. Our objective was to assess the ability of real-time PCR to predict in vitro resistance in isolates of group B streptococcus (GBS). Methods. The first real-time PCR assays for the genes known to confer resistance to erythromycin and clindamycin in GBS were developed. Three hundred and forty clinical GBS isolates were assessed with these assays and compared with conventional disk diffusion. Results. The presence of an erythromycin ribosome methylation gene (ermB or ermTR variant A) predicted in vitro constitutive or inducible resistance to clindamycin with a sensitivity of 93% (95% CI 86%–97%), specificity of 90% (95% CI 85%–93%), positive predictive value of 76% (95% CI 67%–84%), and negative predictive value of 97% (95% CI 94%–99%). Conclusion. This rapid and simple assay can predict in vitro susceptibility to clindamycin within two hours of isolation as opposed to 18–24 hours via disk diffusion. The assay might also be used to screen large numbers of batched isolates to establish the prevalence of resistance in a given area.