Mobile colistin resistance (mcr) genes (mcr-1 to mcr-10) threaten the efficacy of colistin (COL), a polymyxin antibiotic that is used as a last-line agent for the treatment of deadly infections caused by multidrug-resistant and extensively drug-resistant bacteria in humans and animals. COL has been used for more than 60 years for the prophylactic control and treatment of infections in livestock husbandry but not in horses. Polymyxin B is used for the prophylactic control and empirical treatment of infections in horses without conducting sensitivity tests. The lack of sensitivity testing exerts selection pressure for the acquisition of the mcr gene. By horizontal transfer, mcr-1, mcr-5, and mcr-9 have disseminated among horse populations globally and are harbored by Escherichia coli, Klebsiella, Enterobacter, Citrobacter, and Salmonella species. Conjugative plasmids, insertion sequences, and transposons are the backbone of mcr genes in the isolates, which co-express genes conferring multi- to extensive-drug resistance, including genes encoding extended-spectrum β-lactamase, ampicillinase C, fosfomycin, and fluoroquinolone resistance, and virulence genes. The transmission of mcr genes to/among bacterial strains of equine origin is non-clonal. Contact with horses, horse manure, feed/drinking water, farmers, farmers’ clothing/farm equipment, the consumption of contaminated horse meat and its associated products, and the trading of horses, horse meat, and their associated products are routes for the transmission of mcr-gene-bearing bacteria in, to, and from the equine industry.
Mobile colistin resistance (mcr) genes (mcr-1 to mcr-10) are plasmid-encoded genes that threaten the clinical utility of colistin (COL), one of the highest-priority critically important antibiotics (HP-CIAs) used to treat infections caused by multidrug-resistant and extensively drug-resistant bacteria in humans and animals. For more than six decades, COL has been used largely unregulated in the poultry sector in low- and middle-income countries (LMICs), and this has led to the development/spread of mcr gene-containing bacteria (MGCB). The prevalence rates of mcr-positive organisms from the poultry sector in LMICs between January 1970 and May 2023 range between 0.51% and 58.8%. Through horizontal gene transfer, conjugative plasmids possessing insertion sequences (ISs) (especially ISApl1), transposons (predominantly Tn6330), and integrons have enhanced the spread of mcr-1, mcr-2, mcr-3, mcr-4, mcr-5, mcr-7, mcr-8, mcr-9, and mcr-10 in the poultry sector in LMICs. These genes are harboured by Escherichia, Klebsiella, Proteus, Salmonella, Cronobacter, Citrobacter, Enterobacter, Shigella, Providencia, Aeromonas, Raoultella, Pseudomonas, and Acinetobacter species, belonging to diverse clones. The mcr-1, mcr-3, and mcr-10 genes have also been integrated into the chromosomes of these bacteria and are mobilizable by ISs and integrative conjugative elements. These bacteria often coexpress mcr with virulence genes and other genes conferring resistance to HP-CIAs, such as extended-spectrum cephalosporins, carbapenems, fosfomycin, fluoroquinolone, and tigecycline. The transmission routes and dynamics of MGCB from the poultry sector in LMICs within the One Health triad include contact with poultry birds, feed/drinking water, manure, poultry farmers and their farm workwear, farming equipment, the consumption and sale of contaminated poultry meat/egg and associated products, etc. The use of pre/probiotics and other non-antimicrobial alternatives in the raising of birds, the judicious use of non-critically important antibiotics for therapy, the banning of nontherapeutic COL use, improved vaccination, biosecurity, hand hygiene and sanitization, the development of rapid diagnostic test kits, and the intensified surveillance of mcr genes, among others, could effectively control the spread of MGCB from the poultry sector in LMICs.
Widespread COVID–19 vaccination is essential to maintaining pandemic control. However, low–and lower–middle–income countries (LMICs) continue to face challenges to care due to unequal access and vaccine fear despite the introduction of safe and effective immunisations. This study aimed to collect information on Nigeria's COVID–19 vaccine uptake rates and determinants. Science Direct, PubMed, Google Scholar, African Journal Online, Springer, and Hinari were all systematically searched through and completed in May 2022. Quality assessments of the listed studies were performed using the eight–item Joanna Briggs Institute Critical Appraisal tools for cross–sectional studies. In addition, we undertook a meta-analysis to calculate pooled acceptance rates with 95% confidence intervals (CI). Forty–two studies in total satisfied the inclusion criteria and were reviewed. A total of 24,533 respondents were studied. The total sample size of states in the Northern, Western and Southern parts of Nigeria are 3,206, 4,527 and 5,059, respectively, while 11,741 is the cumulative sample size of all the Nigeria-wide studies. The total COVID–19 vaccination acceptance rate among all the study groups was 52.4% (95% CI: 46.9–57.9%, I2 = 100%), while the total estimated COVID–19 vaccination hesitancy rates was 47.81% (95% CI: 42.2 – 53.4% I2 = 100%). In Nigeria–regions sub–group analyses, the Western region (58.90%, 95% CI: 47.12–70.27%) and Northern region (54.9%, 95% CI: 40.11%–69.4%) showed the highest rates of vaccine acceptance and vaccine hesitancy respectively. The COVID–19 vaccine acceptance rate was highest in 2020, with a pooled rate of 59.56% (46.34, 57.32%, I2 = 98.7%). The acceptance rate in 2021 was only 48.48 (40.78%, 56.22%), while for the studies in 2022, it increased to 52.04% (95% CI: 35.7%, 68.15 %). The sensitisation of local authorities and the dissemination of more detailed information about the COVID–19 vaccine and its safety, could significantly increase the country's vaccination rate.
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