Phenotypic and molecular characterization of Methicillin Resistant Staphylococcus aureus from surgical patients and normal dogs

Abstract

Njoroge C, Mande JD, Mitema SE, Kitaa JMA. 2018. Phenotypic and molecular characterization of Methicillin Resistant Staphylococcus aureus from surgical patients and normal dogs. Bioteknologi 15: 13-25. The objectives of this study were to determine bacterial ecology and their antimicrobial susceptibilities from a wound and ear swabs with emphasis on Staphylococcus aureus and to determine the prevalence of MRSA/MRSP in normal dogs and surgical patients using phenotypic and genotypic assays. The findings revealed that the most prevalent microbial isolates recovered from dogs diagnosed with wounds, surgical site infections, and otitis externa, were S. aureus 50% (133/267) and Proteus spp. 14% (38/267). Other frequently recovered isolates included Pseudomonas spp. 10% (28/267), other Staphylococcus spp. 8.2% (22/267), Streptococcus spp. 6.7% (18/267), and E. coli 5.6% (15/267). Resistance to antimicrobial drugs was observed in the majority of the isolates in the retrospective study, with 97% (262/267) of the isolates demonstrating antimicrobial resistance to at least one drug. Resistance to sulphonamides (96%), potentiated sulphonamides (89%), ampicillin (68%), amoxicillin (62%) and tetracycline (56%) was relatively high for all bacterial species examined. S. aureus isolates showed 95% resistance to sulfamethoxazole, 55% to ampicillin, 52% to tetracycline and 52% to amoxicillin/clavulanic acid. Pseudomonas spp. showed the highest multidrug resistance with all (100%) isolates showing resistance to amoxicillin, amoxicillin/clavulanic acid and sulfamethoxazole, the isolates also showed high resistance to cotrimoxazole (93%), ampicillin (93%) and tetracyclines (80%). Low resistance to gentamicin (9%), norfloxacin (24%) and chloramphenicol (33%) was observed in all bacterial isolates. Data from the prospective study revealed that presumptive Staphylococcus spp. were isolated from 34% (65/191) of the samples. Coagulase-positive Staphylococcus spp. (COPS) accounted for 43% (28/65) of the Staphylococcus spp. isolated. Phenotypic resistance to oxacillin was detected in 53.6% (15/28) of COPS. Further analysis of the resistant determinants by BLAST revealed that all the resistant Staphylococcus strains were S. aureus strains. This study confirms S. aureus as the most prevalent bacterial isolate from wounds, surgical site infections, and otitis externa. Proteus spp., Pseudomonas spp., other Staphylococcus spp., Streptococcus spp. and Escherichia coli in descending order were also frequently isolated. Gentamicin, norfloxacin, and chloramphenicol in that order were the most effective antimicrobial agents in the management of wounds, surgical site infections and otitis externa in the retrospective study. The study reports the first case of MRSA strains in dogs in Kenya which were associated with mobile genetic elements (SCCmec) and had the potential to be transferred from dogs to humans. The MRSA resistant determinants observed are similar to some human-like isolates reported in several countries.