Back

Analysis of macrolide-resistant isolates of Streptococcus pneumoniae gained from the Far East of Russia

Abstract number: 902_p1155

Martynova A.

"
Background:

Macrolide resistance has been reported to be high among pneumococci in Asian countries, but the distribution of these macrolide resistance determinants is not known. The incidence of erythromycin-resistant strains among Streptococcus pneumoniae isolates in such a large territory as the Far East of Russia was approximately 5% until the early 1990s, but nowadays erythromycin-resistant strains have been greatly increasing.

Aims:

To further define molecular mechanisms of macrolides resistance in pneumococci strains at the territory of the Far East of Russia.

Methods:

MICs of penicillin, erythromycin, clarithromycin, and clindamycin were determined by the agar dilution method. PCRs were performed with appropriate primers.

Results:

A total of 35.82% (48 of 134 strains) of the S. pneumoniae strains were resistant to erythromycin with an MIC of 1.0 g/mL. Of these, 31.25% (15 of 48) showed an MLSB phenotype with erythromycin and clindamycin 50% MICs (MIC50s) and MIC90s of 64 g/mL; 66.6% (32 of 48) showed resistance to erythromycin alone (M phenotype), with a MIC50 and MIC90 of 8.0 g/mL. One isolate was positive with both ermB and mefE primers. Of the isolates expressing the MLSB phenotype, only the ermB gene was detected in 86.63% (13 strains of 15) of the isolates by PCR. Two isolates were repeatedly negative on testing for ermB but were positive for ermA gene. All the isolates expressing the M phenotype were positive for the mefE gene by PCR. The majority of the M-phenotype strains (84.37%, or 27 of 32) had constitutive resistance (cML phenotype); only 15.625% of these strains had inducible resistance (iML phenotype). Before 2000, it was recorded (5) that among the erythromycin resistant S. pneumoniae isolates, the majority (78%) had an ML phenotype and 22% had an M phenotype. All S. pneumoniae isolates exhibiting a cML or iML phenotype harboured the ermB gene.

Conclusion:

This study indicated a high percentage of erythromycin resistance among clinical isolates of S. pneumoniae in the Far East of Russia. It requires a more careful approach to diagnostics of macrolide resistance in pneumococci in the clinical microbiology laboratory, particularly in areas with high rates of macrolide resistance.

"

Session Details

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