The prevalence of multidrug resistance among Streptococcus pneumoniae in the United States

Abstract number: 1134_02_286

Blosser R., Tillotson G., Flamm R.K., Styers D.A., Sahm D.F., Jones M.


In the U.S., recent approval of antimicrobial agents (e.g. gemifloxacin [GEM]) with indications for multiple drug resistant (MDR) S. pneumoniae (SP) demonstrates a positive industry and governmental response to the need for development of agents against resistant (R) pathogens. This mandates the need for surveillance initiatives to track MDR, as opposed to tracking a single agent's resistance (e.g. penicillin [PEN]). We investigated the current status of MDR among recent clinical isolates of SP distributed throughout USA.


TSN Database–USA (Jan–Dec, 2003) was used to evaluate the current prevalence of the MDR SP in nine geographic urban areas (Atlanta, Baltimore/DC, Carolinas, Central Florida, Chicago, Dallas, Los Angeles, Ohio, South Florida). MDR prevalence was also analysed on the basis of specimen source (upper respiratory [UR], lower respiratory [LR], blood [BL]). MDR was defined as resistance to >=2 among PEN, erythromycin (ERY), and trimethoprim-sulfamethoxazole (SXT). We also selected 30,2003 MDR SP clinical strains to evaluate the relative in vitro activities of respiratory fluoroquinolones (GEM, gatifloxacin [GAT], moxifloxacin [MXF], and levofloxacin [LFX]).


Among SP from all regions combined, the MDR rate was 19.2%. R to PEN, ERY, and SXT was the most common phenotype. Regionally, MDR ranged from 9.1% in Los Angeles to 32.2% in South Florida. R to PEN, ERY, and SXT was the most common MDR phenotype in all regions except Baltimore/DC (R to ERY and SXT was most common). By specimen source, 15.5% of blood, 21.0% of LR, and 29.0% of UR isolates were MDR with R to PEN, ERY, and SXT being the most common phenotype regardless of specimen source. For the 30 strains tested, the fluoroquinolone MIC ranges were: 0.008–0.03 mg/L (GEM), 0.12–0.25 mg/L (GAT), 0.06–0.25 mg/L (MXF), 0.5–1 mg/L (LFX).


MDR among SP is a phenotype that is widely dispersed geographically and is likely to be encountered regardless of the site of infection. Fluoroquinolones show activity against most MDR isolates. As the use of fluoroquinolone compounds increases, surveillance to monitor the prevalence of MDR and track the in vitro activity of agents such as GEM used for these resistant strains must be continued.

Session Details

Date: 01/08/2007
Time: 00:00-00:00
Session name: XXIst ISTH Congress
Location: Oxford, UK
Presentation type:
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