[Antibiotic resistance of Gram-positive cocci isolated in 2008].

Abstract

Objective: Antibiotic resistance evaluation of Gram-positive cocci isolated in 2008.

Material and methods: Antibiotic susceptibility testing was performed for 1044 strains: 610 Staphylococcus aureus (352 from patients, 258 from carriers), 203 Streptococcus pneumoniae (53 from patients, 150 from carriers), 144 Enterococcus faecalis. 57 Enterococcus faecium and 30 Streptococcus spp. using automatic systems Vitek 2 Compact. MicroScan, disc diffusion method and Etest according to 2008 CLSI. A number of 497 Streptococcus pyogenes strains were tested for eritromycin resistance.

Results: There were 33.2% MRSA for strains isolated from patients and 30.0% from carriers. From MRSA strains. 35.5% were resistant to gentamicin. 33.6% to ciprofloxacin, 74.3% to erythromycin and 30.5% to rifampin. There were no S. aureus strain resistant to vancomycin and linezolid. S. aureus strains isolated from wounds were more resistant to erythromycin (43.9%) than the strains isolated from systemic infections (12.1%). From 11 S. pneumoniae strains isolated from meningitis, 4 were resistant to penicillin. Neither S. pneumoniae strain isolated from other infections, nor those from carriers had MIC to penicillin more than 4 microg/ml. S. pneumoniae strains isolated from carriers were more resistant to erythromycin. clindamycin and tetracycline than the strains isolated from patients (66.7%, 54.1%, 54.2% vs. 27.4%, 22.6%, 33.9%). E. faecium was 95.9% resistant to penicillin, 90.2% to ampicillin, 64.7% to gentamicin, 72.0% to streptomycin and 78.4% to ciprofloxacin. F. faecalis was less resistant than E. faecium at most of the antibiotics: 32.4% to gentamicin, 59.6% to streptomycin, 28.5% to ciprofloxacin. Viridans group Streptococci, all isolated from blood culture were 92% susceptible to penicillin and ampicillin. To erythromycin, 12% of viridians group Streptococci were resistant. S. pyogenes resistance to eritromycin was 5.8%.

Conclusions: S. aureus strains showed a relatively high level of resistance to oxacillin (33.2%) and resistance in the same time to several antibiotics. S. pneumoniae can not be considered resistant to penicillin administrated parenteral, with exception of the strains isolated from meningitis. E. faecium had a higher resistance rate than E. faecalis.