Comparative Studies of Escherichia Coli and Salmonela Servars isolated from Kafue Lechwe and Pastrol Cattle in the Interface Areas of the Kafue Flats of Zambia
Mubita, Charles Miyanda
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This study was conducted at Lochinvar and Blue Lagoon National Parks in the interface areas of wildlife and livestock of the Kafue Flats of Zambia to establish the prevalence and relatedness of Escherichia colt and Salmonella serogroups isolated from Kafue Lechwe (Kobus leche kafuensis) and pastoral cattle. A total of 593 faecal samples were processed of which 232 (39.1%) were from Kafue lechwe while 361 (60.8%) were from pastoral cattle. Seventy-seven (33.2%) of 232 samples were compound faecal contents from rectum (R), ceacum (C), small intestine (SI) and the ileo-ceacal junction(ICJ) of each carcass, while 155 (66.8%) were faecal droppings conveniently picked from the grazing pastures. Altogether, there were 1283 presumptive E. coll isolates from Kafue lechwe and pastoral cattle out of which 248 (19.3%) had growth characteristics as Shiga toxin-producing E. coli O157 (STEC) on sorbitol MacConkey agar and CHROMagar O157. Of 248 suspected STEC isolates, 104 (41.9%) were from Kafue lechwe while 144 (58.1%) were from pastoral cattle. Only 18 out of 104 (17.3%) E. coli isolates from Kafue lechwe were serogrouped into 8 serogroups while E. coli isolates from pastoral cattle were typed into 16 serogroups. In case of Salmonella, 59 isolates from Kafue lechwe were identified on biochemical and physiological characterization, of which 39 were from Lochinvar NP, while 20 were from Blue-lagoon NP. Nineteen (32.2%) were confirmed on serological typing with Salmonella somatic polyvalent antisera, while 40 (67.8%) were non-typeable. Furthermore, of the 19 Salmonella isolates, 5 (26.3%) were identified to belong to serogroup 8 serovars while the rest did not react to the available Salmonella antisera groups. Thirty suspected Salmonella isolates were isolated and biochemically identified from faecal samples of the pastoral cattle, out of which 13 (43.3%) tested positive on agglutination test with Salmonella polyvalent antisera while the rest of the isolates were non-typeable. Only one (3.3%) isolates was found to belong to Salmonella group 8. Most E. coli isolates from Kafue lechwe were resistant to metronidazole (98.8%) a drug for protozoan and anaerobic infections, followed by penicillin G (97.6%) and amoxicillin (29%) drugs targeting gram positive bacteria. Resistance to co-trimoxazole was also observed (15.1%). All the E. coli isolates from pastoral cattle were resistant to metronidazole, while resistance to other antimicrobials tested (co-trimoxazole, oxacillin, tetracycline, amoxicillin, cephalexin and penicillin G) showed values below 7.1%. The antibiotics to which Salmonella isolates from Kafue lechwe were most resistant to were metronidazole (100%), followed by penicillin G (89.2 %), co-trimoxazole (67.7%), cephalexin (59.5%) and gentamycin (18.9%). Salmonella isolates from pastoral cattle were most resistant to metronidazole (90.9%), followed by penicillin G (72.7 %), and gentamycin (54.5%). None of the isolates were resistant to amoxicillin, co-trimoxazole, oxacillin and tetracycline. Similarly, the study showed that Salmonella serovars from Kafue lechwe and pastoral cattle had an identical pattern of antimicrobial resistance, suggesting they were related. Escherichia coli and Salmonella isolates from Kafue lechwe and pastoral cattle in the wildlife/cattle Interface Areas of Kafue Flats were examined for the presence of virulence genes capable of causing diseases in humans. Of the 55 E. coli isolates tested, 33 (60%) were found to harbour one of the virulence genes. Out of 33 isolates, 28 (84.8%) were positive to Enteroaggregative Escherichia coli (EAEC) heat-stable toxin 1 (EAST1) gene, with E. coli isolates from cattle being the most predominant in this group (18/28) (64.3%). Out of 53 Salmonella isolates, 39 (73.6%) were positive to invA gene of which 19 (48.7%) isolates were serologically positive to Salmonella polyvalent O antisera, while the rest were non-typeable. All the Salmonella isolates belonging to serogroup 8 were positive to invA gene. These results demonstrate the potential of Kafue lechwe and pastoral cattle faeces as a possible vehicle for transmission of pathogenic and multi-drug resistance diarrheagenic E. coli and Salmonella in the Interface Areas of Kafue Flats, Zambia.
- Veterinary Medicine