The public health significance of enterococci from dairy cattle in Lusaka province, Zambia.
Loading...
Date
2023
Authors
Mutalange, Matenge
Journal Title
Journal ISSN
Volume Title
Publisher
The University of Zambia
Abstract
Enterococci are commensal Gram-positive bacteria found in the intestines of humans and animals, but can also cause infections. Enterococcus faecalis and Enterococcus faecium are a common cause of urinary tract infections, wound infections, bacteremia, infective endocarditis in humans and bovine mastitis in dairy animals. Notably, Enterococci infections in the nosocomial setting (hospital-acquired infections) are usually difficult to treat while Infections of animals with Enterococci are rarely targeted explicitly with antimicrobial agents. However, as normal inhabitants of the intestinal tract, Enterococci are exposed to antimicrobial selection every time animals are exposed to antimicrobials. Thus, Enterococci inhabiting non-human reservoirs such as poultry and cattle play a critical role in acquiring and disseminating antibiotic resistance determinants. Antibiotic-resistant bacteria associated with animals may be easily transmitted to humans via food chains such as milk, meat and eggs. These resistant bacteria are also widely distributed in the environment via animal and human waste. Currently, there is little information about Enterococci infections in the dairy cows in Zambia. Therefore, this study was conducted to evaluate the public health significance of Enterococcus species in milk and faecal matter of dairy cow in Lusaka province, Zambia. This cross-sectional study was carried out from September 2022 to March 2023 in selected districts of Lusaka Province, including Chilanga, Chongwe, and Lusaka districts. Three cows from each farm were randomly selected and both milk and faecal matter were collected and thus ninety-nine raw milk and 99 faecal samples were collected from 33 dairy farms. Both milk and faecal samples were processed to isolate Enterococcus species using standard microbiology procedures. Enterococcus species were tentatively identified based on phenotypic characterisation and confirmed with polymerase chain reaction (PCR) utilising the tuf gene. PCR was also used to speciate Enterococci using the SodA gene for E. faecalis and E. faecium. In order to determine susceptibility patterns, isolates were subjected to seven different antibiotics using the Kirby-Bauer disk diffusion method, while vancomycin-resistant isolates on disc diffusion were subjected to minimum inhibitory concentration (MIC) testing using the E-strip method. Erythromycin-resistant isolates were screened for the presence of erm A, B, and C resistance genes. Enterococci recovery rate was (40%) and (90%) in milk and faecal samples, respectively. Using the tuf gene, the 50 randomly selected isolates were confirmed as, Enterococci species, of which (22%) were E. faecalis and (8%) were E. faecium. Antibiotic susceptibility patterns showed the highest resistance was to ampicillin, 63% and 57% in faecal matter and raw milk, respectively. The faecal matter Enterococci isolates had the highest resistance patterns in almost all the antibiotics except tetracycline and chloramphenicol. The prevalence of multi-drug resistance was 15% and 34% in milk and faecal matter isolates, respectively. The prevalent erythromycin resistance gene was erm B. The detection of Enterococci spp. in milk indicates poor hygienic conditions and contamination and, thus, a public health threat as Entrococci may be transmitted to humans through milk consumption. These findings highlight need to formulate education programs to farmers on good hygiene practices to prevent dissemination.
Description
Thesis of Master of Science in Tropical Infectious Diseases and Zoonosis.