Prevalence of antimicrobial resistance from bacterial culture and susceptibility records from horse samples in South Africa

The continuous increase in prevalence of antimicrobial resistant bacteria presents a significant public health problem and is an indicator that antimicrobial prudent usage guidelines are not being followed, especially in developing countries. Despite trends being available from numerous countries, there is little published for South Africa. This study was aimed at estimating the prevalence and trends of antimicrobial resistance from bacterial isolates from equine clinical samples submitted for culture and susceptibility testing to the veterinary bacteriology laboratory of the University of Pretoria. The study covered a period of seven years from 2007. A total of 1505 bacterial isolates were included in this study comprising isolates from 2007 (n = 447); 2008 (n = 285); 2009 (n = 258); 2010 (n = 102); 2011 (n = 89); 2012 (n = 248) and 2013 (n = 76). For this study, multiple drug resistance was above 50% for all the isolates. The Cochran-Armitage test showed evidence of a significantly increasing trend in prevalence of resistance to several antimicrobial agents, including amikacin (E. coil, Staphylococcus), AMX/AMP (Corynebacteria, Lactobacillus. and Salmonella), chloramphenicol (Enterococcus, E. coli, Pseudomonas, Streptococcus, Staphylococcus and Salmonella), enrofloxacin (E. coil, Staphylococcus, Salmonella and Pseudomonas) and gentamicin (Salmonella, Staphylococcus). The data obtained from this study is relevant to equine practitioners, as it helps enhance the body of veterinary knowledge pertaining to antimicrobial resistance in common equine pathogens in South Africa.