Determination of the occurrence, virulence genes, and antimicrobial resistance profiles of enterococcus faecalis and enterococcus faecium isolated from poultry of Chongwe, Lusaka, Kitwe, and Ndola districts, farmworkers from the Copperbelt province poultry farms and clinical specimens from Kitwe teaching hospital in Zambia.
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Date
2024
Authors
Mwikuma, Grace
Journal Title
Journal ISSN
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Publisher
The University of Zambia
Abstract
Enterococcus has great genetic plasticity and is highly versatile, hence does not only acquire and express mobile genetic elements (MGEs) but also disseminates them to pathogenic and non-pathogenic species of the same or of different genera. As such, it has been associated with various clinical syndromes and is ranked among the major causes of nosocomial infections worldwide. The study aimed to determine the occurrence, virulence
genes, and antimicrobial resistance profiles of Enterococcus faecalis and Enterococcus faecium isolated from poultry of Chongwe, Lusaka, Kitwe, and Ndola Districts, Farmworkers from the Copperbelt Province Poultry Farms, and Clinical Specimens from Kitwe Teaching Hospital in Zambia. A total of 833 samples comprising 492 poultry droppings, 108 urine, and 3 rectal swabs from farmworkers, and 138 urines, 89 stool, and 3 pus swabs from patients attending Kitwe Teaching Hospital were processed. Phenotypic methods were employed to identify Enterococcus while confirmation and species identity were determined by genotypic methods. Drug resistance patterns were determined using the standard disc diffusion method and interpreted according to CLSI 2020 guidelines. Polymerase chain reaction was used to identify and detect resistance and virulence genes. In this study the prevalence of Enterococcus was 31.1% in poultry, 30.8% in farmworkers’ specimens (all being E. faecalis), and 29.6% in clinical samples (with E. faecalis making up 58.8% of these). Both E. faecalis and E. faecium showed high resistance to several antibiotics, with E. faecium generally more resistant than E. faecalis. The majority of E. faecalis isolates were multidrug-resistant, with 89.7% in poultry, 75% in farmworkers, and 97.4% in clinical samples. All E. faecium isolates in clinical samples were multi-drug resistant (MDR). The widespread MDR pattern was resistance to ampicillin,
chloramphenicol, ciprofloxacin, erythromycin, nitrofurantoin, penicillin, tetracycline, vancomycin combination. The frequently detected resistance genes in E. faecalis were tetK and tetM from Kitwe and Ndola, respectively, and in E. faecium, it was aac(6′)-Ieaph(2″)-LA and ermB from Kitwe, and aac(6′)-Ie-aph(2″)-LA from Lusaka. In farmworkers, the frequently detected resistance gene in E. faecalis was tetL. In clinical specimens, the commonly detected resistant gene in E. faecalis was ermB, and in E. faecium, it was aac(6′)-Ie-aph(2″)-LA and tetM. The study also investigated the presence
of gelatinase, aggregation substance, enterococcal surface protein, cytolysin, pheromone cAD1 precursor lipoprotein, E. faecalis endocarditis antigen Regulator of gelE and sprE expression and collagen-binding cell wall protein in E. faecalis and E. faecium, and E. faecium specific cell wall adhesion. Overall, 95.5% of all E. faecalis and E. faecium isolates possessed one of the virulence genes tested. The most prevalent virulence gene was ace being found in 95.5% of all isolates, followed by cad1. The least common virulence gene was esp which was detected in 56.0% of all E. faecalis and E. faecium isolates. The findings indicate a potential for the transmission of antibiotic-resistant strains between these populations and suggest the possibility of zoonotic transmission. Poultry and its products can be contaminated thereby posing a threat to consumers. There is also the possibility of increased healthcare costs and a higher risk of treatment failure due to infection with resistance strains. The discovery highlights the need for enhanced surveillance and monitoring of antibiotic resistance and virulence genes in both human and animal populations as well as other settings.
Description
Thesis of Doctor of Philosophy in Microbiology.