MULTIDRUG-RESISTANT GRAM-POSITIVE PATHOGENS - AN UPDATE ON CURRENT MICROBIOLOGICAL PATTERNS

Although resistance has developed among Gram-positive pathogens to pen icillins, cephalosporins, aminoglycosides, quinolones and macrolides, the glycopeptides seem to remain largely unaffected. However, the rece nt emergence and range of glycopeptide resistance in enterococci, well documented in the USA but not in the rest of the world, have prompted this European surveillance study. The European Glycopeptide Resistanc e Survey was undertaken in 1995 in 9 countries and involved 70 microbi ological centres. The primary aims of the survey were as follows: (i) to perform a microbiological quality assurance assessment to evaluate the ability of participating laboratories to correctly identify the st rains and assess their glycopeptide susceptibility; and (ii) to accura tely determine the level of glycopeptide resistance among staphylococc i, streptococci and enterococci in European hospitals. The in vitro ac tivity of several other antibiotics was assessed on strains isolated f rom the Italian centres. In total, 7078 Grampositive isolates were col lected in Europe, and national coordinators used the National Committe e for Clinical Laboratory Standards (NCCLS) agar dilution reference me thod to successfully retest 96% of these. According to mode minimum in hibitory concentrations (MICs), teicoplanin activity was similar to th at of vancomycin against Staphylococcus aureus. In general, the range of MICs for teicoplanin was wider than that for vancomycin against coa gulase-negative staphylococci. Against Enterococcus spp. and Streptoco ccus spp., teicoplanin was 4 times more active than vancomycin. The gr eatest number of glycopeptide refractory organisms was evident among e nterococci; resistance was observed to be approximately 10 times more frequent in Enterococcus faecium than in E. faecalis. The results from the Italian isolates were similar to those from the overall study. In particular, teicoplanin was 2-to 8-fold more active than vancomycin a gainst the majority of the enterococci. The incidence of enterococcal resistance was lower in Italy (0.6% for teicoplanin and 0.9% for vanco mycin) than in Europe (1.7% for teicoplanin and 2.3% for vancomycin). This extensive survey confirms that teicoplanin is more active than va ncomycin against enterococci and streptococci, and that both display s imilar potency against staphylococci.