Influence of low-level resistance to vancomycin on efficacy of teicoplanin and vancomycin for treatment of experimental endocarditis due to Enterococcus faecium.
Emergence of vancomycin-resistant strains among enterococci raises a new clinical challenge. Rabbits with aortic endocarditis were infected with Enterococcus faecium BM4172, a clinical strain resistant to low levels of vancomycin (MIC, 16 micrograms/ml) and susceptible to teicoplanin (MIC, 1 micrograms/ml), and against its susceptible variant E. faecium BM4172S obtained in vitro by insertional mutagenesis (MICs, 2 and 0.5 micrograms/ml, respectively). Control animals retained 8 to 10.5 log10 CFU/g of vegetation. We evaluated in this model the efficacy of vancomycin (30 mg/kg of body weight; mean peak and trough serum levels, 27 and 5 micrograms/ml, respectively), teicoplanin (standard dose, 10 mg/kg; mean peak and trough levels, 23 and 9 micrograms/ml, respectively; and high dose, 20 mg/kg; mean peak and trough levels, 63 and 25 micrograms/ml, respectively), gentamicin (6 mg/kg; mean peak and trough levels, 8.6 and less than 0.1 micrograms/ml, respectively), alone or in combination, given every 12 h intramuscularly for 5 days. Teicoplanin standard dose was as active as vancomycin against both strains. Vancomycin was not effective against E. faecium BM4172 but was highly effective against E. faecium BM4172S (7.5 +/- 1.1 log10 CFU/g of vegetation versus 4.9 +/- 1.0 log10 CFU/g of vegetation for vancomycin against E. faecium BM4172 and E. faecium BM4172S, respectively; P = 0.0012). A high dose of teicoplanin was more effective than vancomycin against E. faecium BM4172 (4.4 +/- 1.8 log10 CFU/g of vegetation versus 7.5 +/- 1.1 log10 CFU/g of vegetation for teicoplanin high dose and vancomycin, respectively; P less than 0.05). Against E. faecium BM4172 glycopeptide-gentamicin combinations were the most effective regimens in vitro and in vivo (2.8 +/- 0.7 and 3.5 +/- 1.3 log10 CFU/g of vegetation for vancomycin plus gentamicin and teicoplanin standard dose plus gentamicin, respectively; P < 0.05 versus single-drug regimens). We concluded that high-dose teicoplanin or the combination of a glycopeptide antibiotic plus gentamicin was effective against experimental infection due to E. faecium with low-level resistance to vancomycin.
Fantin
B
B
Service de Médecine Interne, Hôpital Bichat, Université Paris VII, France.
Leclercq
R
R
Arthur
M
M
Duval
J
J
Carbon
C
C
D000818:Animals; D000900:Anti-Bacterial Agents / Q000627:therapeutic use*; D004352:Drug Resistance, Microbial; D004359:Drug Therapy, Combination / Q000627:therapeutic use; D004697:Endocarditis, Bacterial / Q000188:drug therapy* / Q000382:microbiology; D016984:Enterococcus faecium / Q000187:drug effects* / Q000235:genetics; D005260:Female; D006020:Glycopeptides / Q000627:therapeutic use; D016908:Gram-Positive Bacterial Infections / Q000188:drug therapy* / Q000382:microbiology; D008826:Microbial Sensitivity Tests; D016254:Mutagenesis, Insertional / Q000502:physiology; D011817:Rabbits; D017334:Teicoplanin; D014640:Vancomycin / Q000627:therapeutic use*
D000900:Anti-Bacterial Agents; D006020:Glycopeptides; D017334:Teicoplanin; D014640:Vancomycin