Distribution across the USA of macrolide resistance and macrolide resistance mechanisms among Streptococcus pneumoniae isolates collected from patients with respiratory tract infections:: PROTEKT US 2001-2002

Background: Resistance to the macrolides has increased rapidly among isolates of Streptococcus pneumoniae from community-acquired respiratory tract infections (CARTIs). Methods: A total of 10 012 S. pneumoniae isolates were submitted from 46 US states and the territory of Puerto Rico in the PROTEKT US Year 2 (2001-2002) surveillance study. Antimicrobial susceptibilities were determined according to NCCLS guidelines and genes encoding common macrolide resistance mechanisms were sought by PCR. Results: Overall, 27.9% (n=2793) of S. pneumoniae isolates were macrolide (erythromycin) resistant; the highest prevalence was recorded in Louisiana (48.2%). Of the 2738 genotyped macrolide-resistant S. pneumoniae, 68.7% possessed mef(A) (state range: Delaware 40.0%-Georgia 84.8%), 16.8% of isolates harboured erm(B) (Georgia 6.1%-Idaho and Rhode Island both 36.4%) and 12.2% possessed erm(B) + mef(A) (Arkansas and Rhode Island 0%-South Dakota 32.9%). Five isolates possessed an erm(A) subclass erm(TR) gene (from California, Illinois, Missouri, Pennsylvania and Virginia), while the mechanisms for 56 isolates were not definable by the methods used in this study. Susceptibility to telithromycin was high, irrespective of macrolide resistance mechanism, with greater than or equal to96.4% of the macrolide-resistant isolates susceptible. Conclusions: The prevalence of macrolide resistance and the resistance mechanisms among S. pneumoniae isolates are highly variable among the US states. Telithromycin may represent an effective treatment option for CARTIs caused by macrolide-resistant pneumococci.