Evaluation of the public health significance of escherichia coli and klebsiella pneumoniae in milk and soil from environment on dairy farms in Lusaka, Zambia.

Escherichia coli and Klebsiella spp. are the most common coliforms that cause clinical mastitis and are responsible for the disease in about 40% of cases in dairy animals. The presence of E. coli and K. pneumoniae in raw milk poses a threat to human health as consumption of contaminated raw milk may cause diseases such as diarrhoea, haemolytic colitis, haemolytic uremic syndrome, urinary tract infections (UTIs), wound infections, nosocomial infections, meningitis in infants, pyogenic liver abscess, necrotizing fasciitis, endophthalmitis and severe pneumonia. This cross-sectional study aimed to generate knowledge on the presence of E. coli and K. pneumoniae in dairy cattle milk and soil. A total of 180 (90 milk and 90 soil environmental) samples were collected from 30 farms around Lusaka province. Samples were collected and processed using standard microbiological and molecular laboratory procedures. A total of 69 isolates were identified, of which (62) were E. coli (51.6%: milk and 48.4%: soil) and (7) K. pneumoniae (85.7%: milk and 14.3%: soil) and confirmed using uidA and KP-27 genes, respectively. The isolates were subjected to eight antimicrobials for susceptibility testing, with the highest resistance recorded for E. coli and K.
pneumoniae to ampicillin (84%) and ceftazidime (86%), respectively. Isolates that were resistant to tetracycline, cephalosporins and trimethoprim- were subjected to PCR to detect resistance genes and these showed that 33%of them had tet (A), 27% blaCTX-M, 37.8% blaTEM-1, 21.6% blaTEM-2 and 80% for dfrA7, encoding tetracycline, cephalosporin, and trimethoprim-sulphamethoxazole resistance, respectively. In order to presumptively screen for Extended Spectrum Beta Lactamases (ESBLs), isolates resistant to cephalosporins were sub-cultured onto MacConkey agar supplemented with cefotaxime. Isolates that grew on MacConkey cefotaxime agar were further tested for the detection of ESBL genes using PCR. Three out of five isolates (60%) showed the presence of ESBL resistance genes blaCTX-M (1/3) and blaTEM-1 gene (2/3). The presence of antimicrobial-resistant E. coli and K. pneumoniae isolated from milk and the environment indicates poor hygienic conditions and the importance of the One Health approach. In addition, the findings demonstrate the need to control the usage of antibiotics in veterinary medicine better and implement effective surveillance programs.