Differences in antibiotic resistance between MRSA and MSSA strains isolated in Hungary, Austria and Macedonia

Abstract number: 1733_207

Horváth A., Malmos G., Pesti N., Kristóf K., Nagy K., Cekovska Z., Kotolácsi G., Gattringer R., Graninger W., Rozgonyi F.

Objectives: The aim of the study was to compare the quantitative susceptibility of methicillin-resistant (MRSA) and methicillin-sensitive (MSSA) strains of Staphylococcus aureus to antistaphylococcal agents. Antimicrobial sensitivity of 123 MSSA and 158 MRSA strains isolated in Hungary, 115 MSSA and 40 MRSA strains isolated in Austria and 72 MRSA strains isolated in Macedonia were tested.

Methods: Identification of S. aureus strains was performed by classical and molecular methods (presence of catalase, clumping factor, nucA and 23S rDNA genes). The mecA gene was detected by polymerase chain reaction (PCR). Minimum inhibitory concentrations (MICs) of antibiotics were determined by broth microdilution method according to NCCLS/CLSI recommendations. PFGE analysis of the strains is in process.

Results: All tested strains were sensitive to vancomycin. Majority of Hungarian and Austrian MRSA strains were sensitive to amikacin, while 70.8% of Macedonian strains were resistant. Resistance of Austrian and Macedonian MRSA strains to gentamicin exceeded 90%, Hungarian MRSA strains were gentamicin resistant in 73.7%. None of the MRSA strains were sensitive to clindamycin. To clarithromycin, ciprofloxacin, levofloxacin and moxifloxacin more than 90% of MRSA strains were resistant.

All tested MRSA strains were multidrug resistant. The most frequent resistance phenotype of Hungarian and Austrian strains was the resistance to gentamicin, clindamycin, clarithromycin and to fluoroquinolones. The most common phenotype of Macedonian strains was the resistance to these antibiotics and amikacin as well.

Both Hungarian and Austrian MSSA strains were mainly sensitive to aminoglycosides. While MSSA strains were mostly sensitive to clarithromycin, resistance of Hungarian and Austrian MSSA strains to clindamycin were 69% and 77%, respectively. The vast majority of MSSA strains were sensitive to all 3 tested fluoroquinolones, Austrian strains were less sensitive than Hungarians.

Conclusion: Resistance rates and degrees of MRSA strains to a variety of antimicrobials were significantly higher than those of the MSSA strains. Therapeutic options differ according to countries. In MSSA infections all antistaphylococcal drugs except for penicillin and clindamycin can be used, while in MRSA infections for empiric therapy only vancomycin and teicoplanin is recommended.

Supported by OTKA No.: T 46186 and ÖAAD-TéT grant No. A-19/02

Session Details

Date: 31/03/2007
Time: 00:00-00:00
Session name: European Society of Clinical Microbiology and Infectious Diseases
Location: ICC, Munich, Germany
Presentation type:
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