Resistance of Gram-positive Bacteria to Antibiotics: the Trend of Recent Five Years: 1999-2003

Abstract

Despite the advent of potent antimicrobial agents, some bacteria obtained resistance to these antimicrobial agents, like methicillin-resistant Staphylococcus aureus (MRSA) or vancomycin-resistant enterococci (VRE), and thus the significance of the surveillance over the resistance to antimicrobial agents has been emphasized world-wide. We analysed seven Gram-positive bacteria as to their resistance to antimicrobial agents in our hospital for recent five years from 1999 to 2003. MRSA was frequently detected as high as 73% of total isolates of S. aureus. They were multiply resistant to penicillins, cefalosporins and imipenem (IPM), although they were still sensitive to vancomycin (VCM) and teicoplanin (TEIC). The ratio of MRSA isolates originating from outpatients was increased from 3% to 6.5%, suggestive of the increased prevalence of MRSA in the community which our hospital belongs to. S. epidermidis isolates that were resistant to MPIPC have increased from 73 to 83%. S. epidermidis that was resistant to erythromycin (EM), clindamycin (CLDM), levofloxacin (LVFX) and fosfomycin (FOM) also increased. E. faecalis was mostly resistant to EM and FOM, while E. faecium was highly resistant to LVFX, FOM and IPM. The ratio of the isolates that were resistant to minocycline (MINO) among these enterococci decreased during the five years. Resistance to penicillins and EM among S. pneumoniae isolates was detected in 49-64% and 64-79% of all the isolates, respectively. On the other hand, resistance to LVFX was around 3% through the five years. S. pyogenes was generally sensitive to penicillins and cephalosporins.