A comparison of the antimicrobial resistance patterns of gram-positive cocci isolated from community-private and university-affiliated hospitals from Puerto Rico

ABSTRACT

The antimicrobial resistance patterns of 2,462 selected Gram-positive cocci obtained from three Community-Private Hospitals (CPH) and three University-Affiliated Hospitals (UAH) were evaluated utilizing the institutions' antimicrobial susceptibility reports for the year 2000. The objectives of this study were 1) to evaluate the in vitro resistance to selected standard antibiotics of Staphylococcus aureus, Enterococcus faecalis, Enterococcus faecium and Streptococcus pneumoniae clinical isolates, and 2) to compare the antimicrobial resistance patterns between community-private (CPH) and university-affiliated hospitals (UAH). Staphylococcus aureus was the most common Gram-positive isolated organism in CPH (63.3 per cent) followed by E. faecalis (31.0 per cent). In UAH, the most prevalent cocci were E. faecalis (51.7 per cent) followed by S. aureus (43.9 per cent). Enterococcus faecium represented 2.3 per cent and 4.4 per cent of CPH and UAH isolates, respectively. Streptococcus pneumoniae represented 3.4 per cent of the total Gram-positive isolates from CPH, no S. pneumoniae was reported in UAH. The antimicrobial susceptibility results showed that for Staphylococcus aureus there was a statistically significant higher resistance to methicillin and thrimethoprim sulfamethoxazole in UAH, while resistance to erythromycin was significantly higher in CPH. There was no difference in the resistance of S. aureus to other antimicrobial agents between hospitals groups. A statistically significant resistant to vancomycin was found between enterococcal isolates from UAH (43 per cent) and CPH (12.7 per cent). High-level aminoglycoside resistance (HLAR) was observed among UAH enterococcal isolates with E. faecium showing a higher resistance than E. faecalis, no data for HLAR in CPH could be obtained. For pneumococci 46 per cent of CPH isolates were resistant to penicillin. In summary, there are important differences in the prevalence and antimicrobial resistance between the Gram-positive bacteria isolated from community and teaching hospitals.