This Article Full Text Full Text (PDF) Other Versions of this Article: JCM.00868-06v1 44/12/4444    most recent Alert me when this article is cited Alert me if a correction is posted Services Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Reprints and Permissions Copyright Information Books from ASM Press MicrobeWorld Citing Articles Citing Articles via Google Scholar Google Scholar Articles by Schnellmann, C. Articles by Perreten, V. Search for Related Content PubMed PubMed Citation Articles by Schnellmann, C. Articles by Perreten, V.

 Previous Article  |  Next Article 

Journal of Clinical Microbiology, December 2006, p. 4444-4454, Vol. 44, No. 12
0095-1137/06/$08.00+0     doi:10.1128/JCM.00868-06
Copyright © 2006, American Society for Microbiology. All Rights Reserved.

Presence of New mecA and mph(C) Variants Conferring Antibiotic Resistance in Staphylococcus spp. Isolated from the Skin of Horses before and after Clinic Admission

Institute of Veterinary Bacteriology,¹ Equine Clinic,² Department of Clinical Veterinary Medicine, Vetsuisse Faculty, University of Berne, CH-3001 Bern, Switzerland³

Received 25 April 2006/ Returned for modification 16 July 2006/ Accepted 17 September 2006

Because of the frequency of multiple antibiotic resistance, Staphylococcus species often represent a challenge in incisional infections of horses undergoing colic surgery. To investigate the evolution of antibiotic resistance patterns before and after preventative peri- and postoperative penicillin treatment, staphylococci were isolated from skin and wound samples at different times during hospitalization. Most staphylococci were normal skin commensals and belonged to the common coagulase-negative group. In some cases they turned out to be opportunistic pathogens present in wound infections. MICs were determined for 12 antibiotics, and antibiotic resistance genes were detected by microarray. At hospital admission, horses harbored staphylococci that were susceptible to antibiotics or resistant to one group of drugs, mainly due to the presence of new variants of the methicillin and macrolide resistance genes mecA and mph(C), respectively. After 3 days, the percentage of Staphylococcus isolates displaying antibiotic resistance, as well as the number of resistance genes per isolate, increased moderately in hospitalized horses without surgery or penicillin treatment but dramatically in hospitalized horses after colic surgery as well as penicillin treatment. Staphylococcus species displaying multiple resistance were found to harbor mainly genes conferring resistance to ß-lactams (mecA and blaZ), aminoglycosides [str and aac(6')-Ie-aph(2')-Ia], and trimethoprim [dfr(A) and dfr(D)]. Additional genes conferring resistance to macrolides [mph(C), erm(C), and erm(B)], tetracycline [tet(K) and tet(M)], chloramphenicol [cat(pC221) and cat(pC223)], and streptothricin (sat4) appeared in several strains. Hospitalization and preventive penicillin use were shown to act as selection agents for multidrug-resistant commensal staphylococcal flora.

Published ahead of print on 27 September 2006.