Clinical relevance of a European collaborative study on comparative susceptibility of Gram-positive clinical isolates to teicoplanin and vancomycin

Seventy laboratories in nine European countries (Belgium, France, Germany, Italy, The Netherlands, Portugal, Spain, Switzerland and the UK) each collected 100 consecutive Gram-positive bacterial pathogens during 1995. MICs were determined by a co-ordinating laboratory in each country using an agar incorporation method with Mueller Hinton medium (NCCLS). Quality control was ensured by distribution of five test strains to the co-ordinating laboratories. A total of 7078 isolates was collected: 2885 Staphylococcus aureus, 1706 enterococci, 1480 coagulase-negative staphylococci (CNS), 932 Streptococcus spp. (including 289 strains of S. pneumoniae) and 75 miscellaneous species. Of these, the country coordinators successfully re-tested 6824 isolates. Using NCCLS interpretive criteria, overall 39 isolates (including 28 strains of enterococci) were teicoplanin-resistant (0.57%) and 38 (mostly CNS; 0.56%) were intermediate, whilst 32 isolates (including 30 strains of enterococci) were resistant to vancomycin (0.47%) and 7 (all enterococci; 0.10%) were intermediate. The overall resistance rate was ≤0.5%. The two glycopeptides were essentially active against the major pathogens encountered in the survey. The only real difference with clinical implications from previously reported susceptibility data is the emergence and spread of resistance in enterococci, particularly in E. faecium. Resistance was highest in SSTI, UTI, bloodstream and GI infections; no resistance was encountered in RTI, gynaecological infections or central nervous system infections. This resistance was also geographically diverse: Resistance to vancomycin in E. faecalis was present only in France, Germany, Italy, Portugal and Spain (Italy and Spain only for teicoplanin), whilst resistance to teicoplanin and vancomycin in E. faecium was present in all countries except Spain. Eight isolates (0.5% of all enterococci) were vancomycin-resistant but teicoplanin-susceptible, exhibiting the vanB phenotype. These were four strains of E. faecalis and four strains of E. faecium. Whilst isolates of S. haemolyticus had higher MIC of teicoplanin than other CNS, and were more susceptible to vancomycin, overall resistance to teicoplanin was low (3.3% in S. haemolyticus; 0.6% in CNS). S. haemolyticus was a relatively rare pathogen, accounting for 6.3% of all CNS isolates, and 1.4% of all Gram-positives collected. The results of this survey show that, despite occasional nosocomial problems (e.g. with enterococci and S. haemolyticus), teicoplanin or vancomycin remain adequate therapy for infections caused by Gram-positive pathogens in the 1990s.