Abstract
BackgroundShiga toxin–producing Escherichia coli (STEC) O157:H7 is a well-recognized cause of bloody diarrhea and hemolytic-uremic syndrome (HUS). The ability of STEC strains to cause human disease is due to the production of Shiga toxins. The objectives of this study were to determinate the prevalence, serotypes, antibiotic susceptibility patterns and the genetic capability for Shiga toxin production in Escherichia coli (STEC) strains isolated from dairy cattle farms in two rural communities in the Eastern Cape Province of South Africa. MethodsFecal samples were collected between March and May 2014, from individual cattle (n = 400) in two commercial dairy farms having 800 and 120 cattle each.Three hundred presumptive isolates obtained were subjected to polymerase chain reactions (PCR) for identification of O157 serogroup and Shiga toxin producing genes (stx1, stx2) on genomic DNA extracted by boiling method. Susceptibility of the isolates to 17 antibiotics was carried out in vitro by the standardized agar disc-diffusion method. Results Based on direct PCR detection, 95 (31.7 %) isolates were identified as O157 serogroup. The genetic repertoire for Shiga toxin production was present in 84 (88.42 %) isolates distributed as stx1 (37), stx2 (38) and stx1/2 (9) respectively while 11 of the isolates did not harbor Shiga toxin producing genes. Multiple antibiotic resistances were observed among the isolates and genetic profiling of resistance genes identified blaampC 90 %, blaCMY 70 %, blaCTX-M 65 %, blaTEM 27 % and tetA 70 % and strA 80 % genes among the antimicrobial resistance determinants examined.ConclusionWe conclude that dairy cattle farms in the Eastern Cape Province are potential reservoirs of antibiotic resistance determinants in the province.
Highlights
Shiga toxin–producing Escherichia coli (STEC) O157:H7 is a well-recognized cause of bloody diarrhea and hemolytic-uremic syndrome (HUS)
Giving the frequent occurrence of O157 STEC as foodborne pathogen in North America and some parts of the western world, there is a clear need to gather data on the prevalence and distribution of STEC producing E.coli and the antibiotic resistance profiles of isolates of this organism recovered from faecal samples from commercial dairy cattle farms in the Eastern Cape of South Africa where pastoral farming is a major source of income for many families
polymerase chain reactions (PCR)-based detection of virulence genes The 95 molecularly confirmed E.coli O157 isolates were analyzed by PCR for their Shiga toxin producing capabilities
Summary
Shiga toxin–producing Escherichia coli (STEC) O157:H7 is a well-recognized cause of bloody diarrhea and hemolytic-uremic syndrome (HUS). The ability of STEC strains to cause human disease is due to the production of Shiga toxins. The objectives of this study were to determinate the prevalence, serotypes, antibiotic susceptibility patterns and the genetic capability for Shiga toxin production in Escherichia coli (STEC) strains isolated from dairy cattle farms in two rural communities in the Eastern Cape Province of South Africa. Via the food chain, ingest a lot of bacteria originating from food-producing animals, which have been recognized as major reservoirs of E. coli habouring CTX-M β-lactamase an enzyme that confers resistance to β-lactam antibiotics [23]. Ability of isolates to produce Shiga toxin and their antibiotic susceptibility patterns as well as presence of some resistance determinants were screened by molecular approaches
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