[Activity of daptomycin, ciprofloxacin, clindamycin and cotrimoxazole against coagulase-negative Staphylococcus strains with diminished susceptibility to vancomycin].

Introduction: Coagulase Negative Staphylococci (CNS) have become one of the most common nosocomial pathogens and it has a high mortality rate due to the increased of seriously ill patients survival, long states immunosuppression and presence of foreign bodies, such as catheters, prostheses, pacemakers, etc. In addition, there is a significant increase in resistance to antimicrobial drugs, especially beta-lactams, and the increase in the MIC for vancomycin leads to a loss of clinical efficacy. This necessitates the search for new therapeutic alternatives, such as daptomycin. The aim of this paper is to study the activity of daptomycin, ciprofloxacin, clindamycin and cotrimoxazole in two groups of clinically significant CNS: a MIC₉₀with vancomycin ≤ 1 mg/L and the other with MIC₉₀ 2 mg/L.

Methods: We identified and studied MIC₉₀ to ciprofloxacin, clindamycin and cotrimoxazole from 54 strains of clinically significant by the CNS Combo 22 Microscan panels (Dade Behring, Siemens). The MIC₉₀for daptomycin was performed using Etest (AB BioMérieux, Solna, Sweden) on Mueller Hinton plates (BioMérieux, France).

Results: In Group I (vancomycin MIC₉₀ ≤ 1 mg/L) were 19 strains whereas in Group II (vancomycin MIC₉₀ =2 mg/L) were 35 strains. Expressed in mg/L, MIC₉₀ ranges for daptomycin were 0.047-0.5 in Group I and 0.064-0.5 in Group II. for ciprofloxacin were 8 sensitive strains and 11 resistant in Group I and 10 sensitive and 25 resistant in Group II. For clindamycin were 7 sensitive strains and 12 resistant in Group I and 16 sensitive and 19 resistant in Group II. Finally, for cotrimoxazole were 10 sensitive strains and 9 resistant in Group I and 19 sensitive and 16 resistant in Group II.

Conclusions: The MIC levels to daptomycin were not influenced by the increase in the MIC for vancomycin. There was no statistically significant difference for the sensitivity of ciprofloxacin between the two groups of vancomycin. Regardless of vancomycin, there were a clear relationship between the sensitivity of ciprofloxacin with clindamycin and cotrimoxazole.