dalfopristin and Streptococcal-Infections

This study evaluated the current status of antimicrobial resistance in clinical isolates of Streptococcus pyogenes in Taiwan as part of the SMART (Surveillance from Multicenter Antimicrobial Resistance in Taiwan) program. In 2001, 419 different isolates of S. pyogenes, including 275 from respiratory secretions, 87 from wound pus, and 31 from blood, were collected from nine hospitals in different parts of Taiwan. MICs of 23 antimicrobial agents were determined at a central location by the agar dilution method. All of the isolates were susceptible to penicillin (MIC at which 90% of the isolates were inhibited [MIC(90)], moxifloxacin > ciprofloxacin = levofloxacin = gatifloxacin > gemifloxacin) demonstrated potent activity against nearly all of the isolates of S. pyogenes tested. Thirty-two isolates (8%) were not susceptible to quinupristin-dalfopristin. Seventeen percent of isolates had telithromycin MICs of >or=1 microg/ml, and all of these isolates exhibited erythromycin MICs of >or=32 microg/ml. The high prevalence of resistance to telithromycin (which is not available in Taiwan) limits its potential use in the treatment of S. pyogenes infections, particularly in areas with high rates of macrolide resistance.

Topics: Anti-Bacterial Agents; Drug Resistance, Bacterial; Erythromycin; Genes, Bacterial; Humans; Ketolides; Macrolides; Microbial Sensitivity Tests; Phenotype; Streptococcal Infections; Streptococcus pyogenes; Taiwan; Virginiamycin

Macrolide-resistance was assessed in 216 consecutive Streptococcus pyogenes isolates from throat infections in the region of Aachen, Germany. Seventeen isolates were resistant to erythromycin: 12 isolates revealed a macrolide (M) phenotype and harbored mefA, and five strains expressed an inducible macrolide-lincosamide-streptogramin B (MLSB) phenotype of which four strains harbored ermA(TR) and one strain contained ermB(AM). Telithromycin (HMR 3647) and quinupristin/dalfopristin remained active particularly against the ermA(TR)-containing S. pyogenes isolates studied. Random amplified polymorphic DNA analysis identified multiple clones among erythromycin-resistant strains, but did not discriminate beyond the emm-type. mefA was present in three isolates either with emm2, emm12, or emm75, and in nine isolates with emm4. All four strains with ermA(TR) contained emm77, and the single strain with ermB(AM) harbored emm1. Despite the relative low rate of macrolide-resistance, these data suggest that at least three different macrolide-resistance determinants are prevalent in Germany and that mefA has spread rapidly into multiple clones of S. pyogenes.

Topics: Anti-Bacterial Agents; Drug Resistance; Erythromycin; Genotype; Germany; Ketolides; Macrolides; Microbial Sensitivity Tests; Pharynx; Phenotype; Polymorphism, Restriction Fragment Length; Regulon; Respiratory Tract Infections; Reverse Transcriptase Polymerase Chain Reaction; Streptococcal Infections; Streptococcus pyogenes; Streptogramins; Virginiamycin

The emergence and sustained prevalence of Gram-positive organisms resistant to antimicrobials has been of interest for over a decade. Quinupristin/dalfopristin (formerly RP 59500 or Synercid) is a new injectable streptogramin combination that has been reported to have activity against Gram-positive organisms, even those with documented MLS(B) resistance. However, the two case reports presented here illustrate three well-documented Streptococcus spp. strains (S. mitis, S. pneumoniae) to be resistant to quinupristin/dalfopristin (MICs at 3, 8, and 12 microg/ml) following referral as routine isolates in the SENTRY Antimicrobial Surveillance Program. The S. pneumoniae pleural fluid isolate was cross-resistant to erythromycin. Both bacteremic S. mitis strains were resistant to macrolides (erythromycin, azithromycin, clarithromycin), lincosamides (clindamycin), and fluoroquinolones. Patient histories indicated no prior use of MLS class antimicrobials for the S. mitis case, but the patient having the S. pneumoniae isolate did receive prior treatment of erythromycin and clindamycin. All isolates had modestly increased penicillin MICs of 0.12 microg/ml. The mode of resistance to quinupristin/dalfopristin was not evident (sat A-negative by PCR); and these cases illustrate the existence of streptogramin-resistant isolates before the introduction of this antimicrobial class into human clinical practice.

Topics: Adult; Aged; Aged, 80 and over; Anti-Bacterial Agents; Drug Resistance, Microbial; Female; Humans; Male; Streptococcal Infections; Streptococcus; Virginiamycin