| Sumario: | Salmonella species cause significant morbidity, mortality and burden of disease globally. In Kenya, salmonellosis is only second to pneumococcal disease as a leading cause of mortality in children under five; children living in the slums are especially vulnerable. Being a multihost zoonotic pathogen, it is important to understand its epidemiology in various hosts so as design effective control strategies.
This study determined the prevalence of Salmonella in livestock in Korogocho and Viwandani slums. Salmonella serotypes and antibiotic susceptibility patterns among the livestock were also described and compared with those from archived human faecal samples and drinking water isolated from households in the same areas.
Eight hundred and one livestock (cows, chickens, goats, pigs, ducks, rabbits and doves) were sampled from 203 randomly selected livestock-keeping households. Information on various management practices such as housing, nutrition and waste management was collected using questionnaires. Faecal samples were taken for isolation and identification of Salmonella, serotyping and antibiotic susceptibility testing. Likewise, 15 archived Salmonella species from human faecal samples and 1 from drinking water that had been isolated at KEMRI and the University of Nairobi Department of Public Health Pharmacology and Toxicology respectively were serotyped and antibiotic susceptibility determined.
Salmonella were isolated from 5 out 801 (0.62%) of the livestock sampled; 4 out of 561 (0.74%) livestock in Korogocho and 1 out of 259 (0.39%) livestock in Viwandani. The isolation rate ranged from 0% to 5% among the different livestock species (0% in pigs, ducks and goats; 0.35% in chickens; 3.6% in doves; 3.8% in cows and 5% in rabbits). Four of the five livestock isolates and the drinking water isolate were identified as Salmonella typhimurium. The identifiable Salmonella serotypes among the human faecal isolates were; S. Typhi, S. Paratyphi C, S. Heidelberg, S. Newport and one in serogroup C2-C3 that couldn’t be identified further.
All the livestock isolates were susceptible to the thirteen antibiotics tested in this study. The drinking water isolate however had multiple drug resistance to; ampicillin, amoxicillin/clavulanic acid, tetracycline, chloramphenicol, nalidixic acid and ciprofloxacin. Likewise, eighty percent (12/15) of the human isolates were resistant to at least two antibiotics and majority were resistant to 3 (4/15; 26.7%) and 4 (4/15; 26.7%) antibiotics. Sixty percent (9/15) of the isolates were resistant to ampicillin and amoxicillin/clavulanic acid. Significant resistance was also observed towards kanamycin (53%), nalidixic acid (26.7%) and trimethoprim/sulphamethoxazole (26.7%).There was no resistance observed to either cefepime or ciprofloxacin.
BlaTEM (consensus) genes were identified from 10 out of 13(76.9%) and Integron class 1 genes identified from 3 out of 13 (23.1%) resistant isolates (from humans and drinking water). All the ampicillin and amoxicillin/clavulanic acid resistant isolates were positive for the blaTEM (consensus) gene. The isolates that were positive for integron class I also had the blaTEM gene.
Most human isolates showed multiple resistance to commonly used antibiotics indicating possible misuse of antibiotics. There was no resistance to ciprofloxacin and cefepime therefore extra emphasis should be put on the proper use of these antibiotics in treatment of humans to guard against the emergence of resistance.
This study showed that the prevalence of Salmonella in livestock was low and that there was no antibiotic resistance among these isolates in Korogocho and Viwandani at the time of sampling. Presence of resistance genes in the human and drinking water isolates further emphasises the need for judicious use of antibiotics as these are easily transmissible to other community acquired pathogens especially in resource poor settings. The distribution of serotypes and antibiotic susceptibility patterns was also not phenotypically similar across the three sample sources (livestock, drinking water and humans). Additional epidemiological studies across various sources (environment, humans, and animals) however, are necessary to identify significant reservoirs of Salmonella in the community.
|
|---|