Veterinary Medicine

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Detection of extended spectrum beta lactamase producing enterobacterales from diseased chickens and estimation of antimicrobial usage from antibiotics importation and sales data in Lusaka district, Zambia.
(The University of Zambia, 2024) Chileshe, Chikwanda
Poultry products in Zambia form an integral part of the human diet in many households, as they are more affordable and easier to produce as compared to other sources of animal protein. However, the burden of poultry diseases has remained a major challenge, hindering the growing consumer demand for poultry products in Zambia. This has resulted in non-prudent antimicrobial use on farms, with the intent to prevent and treat poultry diseases for growth optimization and maximising profits. This study aimed to identify the different types of extended-spectrum -lactamase (ESBL) producing Gram negative bacteria (GNB) causing diseases in chickens in Lusaka and to asses possible association between antibiotic resistance and antibiotic consumption. A cross-sectional study was conducted in Lusaka, which involved the collection of samples from diseased chickens at three different post-mortem facilities. Importation data was gathered from antimicrobial usage (AMU) data collection report from the Ministry of Fisheries and Livestock (MOFL) whilst sales data was collected from the largest outlet of veterinary pharmaceutical products in Zambia. A total of 215 samples were collected and screened for GNB. Of these samples, 103 tested positive for various clinically relevant Enterobacterales, including Enterobacter (43/103, 41.7%), Escherichia coli (20/103, 19.4%), Salmonella (10/103, 9.7%), and Shigella (8/103, 7.8%). Other isolated bacteria included Yersinia, Morganella, Proteus, and Klebsiella, which accounted for 21.4%. Only E. coli, Enterobacter, Salmonella, and Shigella were subjected to antimicrobial susceptibility testing (AST) using the Kirby-Bauer disc diffusion due to their public health significance. The AST results revealed that E. coli, Enterobacter and shigella were highly resistant to tetracycline, ampicillin, amoxicillin, and trimethoprim-sulfamethoxazole, while Salmonella showed complete susceptibility to all tested antibiotics. The observed resistance patterns correlated with antimicrobial usage estimated from the importation and sales data. The broth microdilution test was used to quantify for cefotaxime resistance. Results from this test showed that only fourteen (14/103, 13.5%) were resistant to cefotaxime. Eight of the fourteen isolates were Enterobacter whilst the remaining six were E. coli. The polymerase chain reaction (PCR) technique was then used to screen for the genes blaCTX-M, blaTEM, blaOXA and blaSHV. All Six (6/14, 42.9%) of the E. coli isolates carried the gene blaCTX-M whilst only four carried the gene blaTEM. On the other hand, all eight (8/14, 57.1%) of the Enterobacter isolates carried the gene blaTEM whilst only four of the isolates harboured the gene blaCTX-M. Sanger sequencing of the PCR products revealed that five (5/6,83.3%) of E. coli isolates carried the blaCTX-M-15 allele. These results suggest the presence of pathogenic ESBL-producing Enterobacteriaceae in poultry, threatening public health.
A meta-analysis on the antibiotic resistance patterns of brucella strains in humans.
(The University of Zambia, 2024) Munang’andu, Mwiza
Brucellosis is a zoonotic disease threatening livestock productivity and human health, especially in low-income regions. Brucella-induced infections present significant treatment challenges due to the limited intracellular penetration of antibiotics, leading to prolonged treatment durations and elevated risks of treatment failure and relapse. The emergence of antibiotic resistance further exacerbates these challenges, presenting an impending public health threat. This study aims to analyze the global prevalence of antibiotic resistant Brucella strains in humans in order to manage and control antimicrobial resistance. A meta-analysis was performed to assess the prevalence of antibiotic resistant Brucella strains. Peer-reviewed research publications were gathered from the 14th August, 2023 to 12th September, 2023, through a literature search utilizing the following keywords :("Brucella") AND "Antibiotic susceptibility," OR "Antibiotic resistance," OR "Antibiotic sensitivity," OR "Antibiotic activity" OR "Antimicrobial susceptibility" OR "Antimicrobial resistance " OR "Antimicrobial sensitivity " OR "Antimicrobial activity" "Antibacterial susceptibility" OR " Antibacterial resistance " OR "Antibacterial sensitivity" OR " Antibacterial activity" OR " Antimicrobial Susceptibility Testing" OR "Microbial Sensitivity" OR "Microbial resistance" OR "Antibiogram") in databases such as PubMed, Google Scholar, and Science-Direct. The study examined online research articles published from 2008 to 2022, specifically concentrating on English studies. A total of 19 eligible studies representing 10 countries and 1, 798 samples were included. Brucella melitensis was isolated in all the studies, with two other Brucella species found in two studies; Brucella abortus in Turkey and Brucella suis in Malaysia. The global pooled prevalence of antibiotic-resistant bacteria was 9% (95% CI: 6-13%). Brucella strains showed the highest antibiotic resistance to macrolides at a prevalence of 58% (95% CI: 0-100%) followed by ansamycins at 35% (95% CI: 17-56%), then betalactams at 7% (95% CI: 0-26%), sulfonamides at 4% (95% CI: 0-19%), aminoglycosides at 1% (0- 1%), and fluoroquinolones, tetracyclines, and cephalosporin at 0% (95% CI: 0-1%). The study observed significant bacterial resistance to macrolides and ansamycins specifically, azithromycin and rifampicin, suggesting the need for an alternate treatment considering that the combination of rifampicin with doxycycline is the recommended treatment of human brucellosis. The study also indicates moderate resistance to sulfonamides and beta-lactams whereas tetracyclines, cephalosporin, fluoroquinolones, and aminoglycosides remain extremely effective.
Risk factors associated with the outbreaks of african swine fever in Lusaka province, Zambia.
(The University of Zambia, 2015) Siamupa, Cynthia M.
African Swine Fever (ASF) is one of the most complex diseases of swine and a worldwide problem with most countries in the sub-Saharan region being endemic. The disease is characterised by widespread hemorrhages and high mortalities and affects trade in pigs and/or pork products both locally and internationally. The aetiological agent for ASF is a DNA virus that does not produce neutralising antibodies in affected animals. Lusaka province of Zambia experienced outbreaks of ASF in 2013. The outbreak was first reported in Lusaka district and later spread to Chilanga and Chongwe districts and a total of 6 471 out of 40 233 pigs were depopulated on 20 farms that were surveyed. The Zambian government incurred a huge cost in terms of loss in trade, cost of control measures and compensation of affected farmers. This study was carried out to identify the risk factors that were associated with these outbreaks in the province. The participants were selected purposively from the four (4) districts of Lusaka province namely; Lusaka, Chilanga, Kafue and Chongwe that had cases of ASF diagnosed by Central Veterinary Research Institute and reported by the Director of Veterinary Services in the 2013-2014 outbreaks. The recruited participants included 3 District Veterinary Officers, 3 Veterinary assistants, 4 police officers and 2 Veterinary staff from veterinary check points, 3 managers from abattoirs and processing plants, 3 meat inspectors from Ministry of Local Government and Housing, 3 market chairpersons, 15 traders and 50 pig farmers. All participants were purposively sampled except for the pig farmers that were included using respondent-driven technique. Apart from managers at abattoirs and processing plants and pig farmers that used semi-structured questionnaires for data collection, all the participants utilized interviews. Interview data and questionnaire responses from managers at abattoirs and processing plants was analysed using narrations, tables and flow charts. Some key statements or quotations emerging from the interviews were used to illustrate the main ideas. Information from the questionnaire for farmers was coded and entered into Microsoft Excel. The coded data was then transferred to STATA® Version 12 (STATA Corporation, College Station, Texas). The variables that could be associated with spread of ASF such as location, duration of pig keeping, alternative source of income, absence of a boar, type of feed, source of feed/ingredient, ASF screening, market availability, knowledge on ASF transmission, occurrence of ASF outbreak and regulation on pig movement were identified. Univariate analysis using Chi-square to determine the effect of each independent variable on the dependant variable (ASF) and multivariate analysis using logistic regression were performed. A confidence interval of 95% was used to ascertain the effects of the above factors on ASF positivity. The P-value for the test was >0.05 meaning that the logistic model used was an adequate fit for the data. The study revealed that farmers bought breeding stock from fellow farmers and live pig markets such as Chibolya market near the Lusaka Central Business District. The farmers (4/50, 8%) that had no boars took their sows to other farms for servicing. Fifty eight per cent (29/50) of the farmers used disinfectants while traders did not disinfect the modes of transport they used. Only 48% (24/50) and 33.3% (5/15) of farmers and traders respectively had knowledge of ASF transmission. Fifty per cent (25/50) of farmers had their animals screened for ASF before sale. All the markets did not have the pork inspected. Further, farmers and traders used alternative routes to avoid check points. The study revealed that the risk factors that were associated with the spread of ASF in Lusaka province were (1) purchase of pigs for replacement and breeding stock from one another and from markets, (2) poor adherence or absence of biosecurity measures, (3) laxity in enforcing livestock movement control and inadequate police and veterinary staff manning check points, (4) evading pig checks at check points by traders who use alternative routes, (5) low awareness levels on ASF transmission among pig farmers and traders, (6) lack of enforcement of regulations at pig markets and (7) inadequate of ASF screening. Of these factors, only absence of a boar (P=0.01, 95% C.I:8.22-68.41) and occurrence of ASF outbreaks in the previous year (P=0.08, 95% C.I:0.23-35.54) were significantly associated with the ASF outbreak. Improving biosecurity, sensitizing farmers, traders and all stakeholders in the pig value chain on ASF, reinforcement of staff at check points and regulation of pig markets are some of the ways in which future outbreaks can be prevented since there is no vaccine or treatment for ASF.
Epidemiology of seasonal influenza and other respiratory pathogens during the COVID-19 pandemic in Zambia.
(The University of Zambia, 2024) Nyahoda, Martin
Respiratory infections are among the leading causes of morbidity and mortality globally especially in Sub-Saharan Africa. In 2021, there were an estimated 344 million global incident episodes attributable to lower respiratory infections translating to an estimated 4350 episodes per 100,000 population resulting in an estimated 2.18 million deaths which was about 27.7 deaths per 100,000 population. Sub-Saharan Africa accounts for about 66.4% of deaths attributable to lower respiratory tract infections per 100,000 persons. In Zambia, severe acute respiratory infections are estimated at 6181 and ranked between 5th and 8th on the top 10 leading causes of death. Between 2019 and 2021, non-pharmaceutical interventions (NPIs) to limit the spread of COVID-19 were implemented globally which included hand washing, face masking, school closures, limiting public gatherings, remote working, hand sanitizing, physical distancing and travel restrictions. This resulted in a decline of respiratory infections especially influenza and respiratory syncytial virus subsequently leading to a decline of all age mortality attributable to lower respiratory infections by 16%. While scientific studies to establish the impact of COVID-19 associated NPIs on circulation of respiratory pathogens have been conducted in several countries globally, there was little knowledge on how the COVID-19 pandemic and its associated public health and social measures changed the epidemiology of influenza and other respiratory infections in Zambia. Therefore, the aim of this study was to determine the broad range of respiratory pathogens that were circulating in Zambia during the COVID-19 pandemic and determine the effects of age and location (rural or urban) on the likelihood of infection. Additionally, through systematic review and meta-analysis, the study sought to ascertain the burden of respiratory infections in Africa and existing regional disparities. This study was retrospective using nasopharyngeal specimens that were collected national wide to test for SARS-CoV-2. After testing for SARS-CoV-2, selected specimens were tested for influenza A virus (IAV), influenza A(H1N1) virus (swine lineage) (IAV(H1N1) swl), influenza B virus (IBV), influenza C virus (IVC), human coronaviruses (HCoV) NL63, 229E, OC43 and HKU1, human parainfluenza viruses (HPIV) 1, 2, 3 and 4, human metapneumoviruses (HMPV) A and B, human rhinovirus (HRV), human respiratory syncytial viruses (HRSV) A and B, human adenovirus (HAdV), enterovirus (EV), human parechovirus (HPeV), human bocavirus (HBoV), Pneumocystis jirovecii, Mycoplasma pneumoniae, Chlamydophila pneumoniae, Streptococcus pneumoniae, Haemophilus influenzae B, Staphylococcus aureus, Moraxella catarrhalis, Bordetella spp. (except Bordetella parapertussis), Klebsiella pneumoniae, Legionella pneumophila / Legionella longbeachae, Salmonella spp. and Haemophilus influenzae in order to understand the profile of pathogens that continued to circulate between July 2020 and July 2021. Proportional age stratified convenient sampling was used to select a total of 128 specimens from children, adolescents, adults and the elderly collected from both urban and rural areas. The final sample consisted 88 from urban and 40 from rural areas collected from Lusaka, Luapula, Northen and Muchinga provinces. Using multiplex rRT-PCR, 128 nasopharyngeal specimens were tested for influenza and other respiratory pathogens. Overall, 71.1% (91/128) of samples tested positive for at least one respiratory pathogen. Staphylococcus aureus was the most prevalent respiratory pathogen detected accounting for 22.7% (29/128) followed by Klebsiella pneumoniae 20.3% (26/128). Influenza accounted for 13.3% (17/128). Of the 17 specimens testing positive for influenza, 16 were influenza A/(H1N1) while one specimen tested positive for influenza B. The prevalence of rhinovirus and respiratory syncytial virus was estimated at 3.1% (4/128) and 2.3% (3/128), respectively. Children, adolescents and the elderly accounted for the most influenza positive specimens 76.5% (13/17) while 100% (3/3) specimens positive for Moraxella catarrhalis were all from children. All specimens that tested positive for Haemophilus influenzae (5/5) were from children and adolescents and 17 of the 29 specimens that tested positive for Staphylococcus aureus were also from the same age group. For co-infections, 52 specimens were found to be co-infected with at least 2 respiratory pathogens. Of the total co-infections, 11.5% (6/52) were virus-virus with adenovirus as the most co-infecting viral pathogen while virus-bacteria co-infections accounted for 48.1% (25/52) with Staphylococcus aureus as the most co-infecting bacterial pathogen. Bacterial respiratory pathogens were more predominant than viral pathogens during the study period. Compared to prevalence prior to the COVID-19 pandemic, a decrease for both viral and bacterial respiratory pathogens was observed. The results seem to suggest that the emergence of COVID-19 and its associated public health interventions may have altered the epidemiology of influenza and other respiratory pathogens in Zambia. Increase in age was associated with an increased risk of infection with adenovirus and SARS-CoV-2 adjusted odds ratio Exp (B) 1.026, CI (0.999-1.053) and 1.048, CI (1.004-1.094) respectively. Although results suggested that rural areas were associated with an increased risk of infection for Bordetella pertussis adjusted odds ratio 3.10, CI (0.667-4.208) and K. pneumoniae adjusted odds ratio 1.588, CI (0.615-4.097) including S. aureus adjusted odds ratio 1.362, CI (0.561-3.303), the results were not statistically significant. At the level of the African continent, overall pooled prevalence for viral respiratory pathogens was estimated at 56.6% (95% CI, 0.371-0.762, I 2 99.9%). Overall pooled prevalence for bacterial respiratory pathogens was estimated at 12.9% (95% CI, 0.122-0.137, I 2 99.8%). Rhinovirus and respiratory syncytial virus were the most prevalent pathogens with wide geographical spread across all African regions with 19.9% and 8.9% prevalence respectively. Generally, most studies in Africa were focused on viral respiratory pathogens. To fully understand the burden of respiratory infections in Africa, there is need for more studies combining both viral and bacterial respiratory pathogens especially with the advent of multiplex PCR. Colonization and enhanced viral induced bacterial binding may have contributed to the persistence of bacterial respiratory infections more than viral pathogens. Co-infections were mostly observed in children because they may be still immunologically naïve and not able to take precautionary measures such as avoiding touching eyes and mouth including frequent hand washing. Although there were observed differences in the prevalence of infection between rural and urban areas, the differences were not statistically significant. Further, and location did not increase the likelihood of infection except for SARS-CoV-2 and adenovirus. Overall, this study demonstrated that with sustained non-pharmaceutical interventions, it is possible to reduce the number of respiratory infections and contribute to improved public health outcomes. Additionally, the high number of bacterial respiratory pathogens detected in this study provides impetus to strengthen efforts to contain these pathogens as they are known to contribute to severe disease and death.
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.
(The University of Zambia, 2024) Mwikuma, Grace
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.

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