Is Africa ready for mobile colistin resistance threat?

Prevalence of colistin-resistant Escherichia coli in foods and food-producing animals through the food chain: A worldwide systematic review and meta-analysis

The purpose of this systematic review and meta-analysis was to summarize the available scientific evidence on the prevalence of colistin-resistant Escherichia coli strains isolated from foods and food-producing animals, the mobile colistin-resistant genes involved, and the impact of the associated variables. A systematic review was carried out in databases according to selection criteria and search strategies established a priori. Random-effect meta-analysis models were fitted to estimate the prevalence of colistin-resistant Escherichia coli and to identify the factors associated with the outcome. In general, 4.79% (95% CI: 3.98%-5.76%) of the food and food-producing animal samples harbored colistin-resistant Escherichia coli (total number of colistin-resistant Escherichia coli/total number of samples), while 5.70% (95% confidence interval: 4.97%-6.52%) of the E. coli strains isolated from food and food-producing animal samples harbored colistin resistance (total number of colistin-resistant Escherichia coli/total number of Escherichia coli isolated samples). The prevalence of colistin-resistant Escherichia coli increased over time (P < 0.001). On the other hand, 65.30% (95% confidence interval: 57.77%-72.14%) of colistin resistance was mediated by the mobile colistin resistance-1 gene. The mobile colistin resistance-1 gene prevalence did not show increases over time (P = 0.640). According to the findings, other allelic variants (mobile colistin resistance 2-10 genes) seem to have less impact on prevalence. A higher prevalence of colistin resistance was estimated in developing countries (P < 0.001), especially in samples (feces and intestinal content, meat, and viscera) derived from poultry and pigs (P < 0.001). The mobile colistin resistance-1 gene showed a global distribution with a high prevalence in most of the regions analyzed (>50%). The prevalence of colistin-resistant Escherichia coli and the mobile colistin resistance-1 gene has a strong impact on the entire food chain. The high prevalence estimated in the retail market represents a potential risk for consumers' health. There is an urgent need to implement based-evidence risk management measures under the "One Health" approach to guarantee public health, food safety, and a sustainable future.

Characterisation of colistin resistance in Gram-negative microbiota of pregnant women and neonates in Nigeria

A mobile colistin resistance gene mcr was first reported in 2016 in China and has since been found with increasing prevalence across South-East Asia. Here we survey the presence of mcr genes in 4907 rectal swabs from mothers and neonates from three hospital sites across Nigeria; a country with limited availability or history of colistin use clinically. Forty mother and seven neonatal swabs carried mcr genes in a range of bacterial species: 46 Enterobacter spp. and single isolates of; Shigella, E. coli and Klebsiella quasipneumoniae. Ninety percent of the genes were mcr-10 (n = 45) we also found mcr-1 (n = 3) and mcr-9 (n = 1). While the prevalence during this collection (2015-2016) was low, the widespread diversity of mcr-gene type and range of bacterial species in this sentinel population sampling is concerning. It suggests that agricultural colistin use was likely encouraging sustainment of mcr-positive isolates in the community and implementation of medical colistin use will rapidly select and expand resistant isolates.

EFFECT OF PENICILLIUM SPECIES ON THE ANTIBIOTIC RESISTANCE PROFILE OF ALCALIGENES FAECALIS

Background

Infectious diseases due to antibiotic resistant pathogens are a global public health problem. This study aimed at determining the potential effect of bacterial-fungal interaction on the antibiotic susceptibility profile of Alcaligenes faecalis.

Materials and Methods

Alcaligenes faecalis was isolated from water samples. The isolate was identified using the conventional biochemical tests and the 16S rRNA molecular sequencing technique. Additionally, Penicillium species was isolated and identified based on colony morphological characteristics and microscopic features. Standardized isolates were co-cultured in broth medium. Antibiotic susceptibility evaluation of the Alcaligenes faecalis from the co-culture and the original Alcaligenes faecalis was carried out using the Kirby bauer disk diffusion method.

Results

The antibiotic susceptibility profile of Alcaligenes faecalis before and after co-culture remained largely unchanged except in the case of chloramphenicol, where the isolate showed reduced susceptibility. Molecular analysis of resistance gene revealed the absence of tested gene encoding antibiotic resistance, including the streptomycin resistance (str) genes (stra and strb) and the erythromycin resistance methylase (erm) gene.

Conclusion

The result of this study showed that there is a minimal influence of Penicillium cultures on the susceptibility of A. faecalis. Further research involving a wide spectrum of microorganisms and their interactions should be conducted to acquire a thorough understanding of the influence of microbial interactions on antibiotic susceptibility profiles in order to pave way for novel strategies to combat antimicrobial resistance.

Molecular Screening of Clinical Multidrug-Resistant Gram-Negative Bacteria Shows Endemicity of Carbapenemases, Coexistence of Multiple Carbapenemases, and Rarity of mcr in South Africa

Background: Extensive use of carbapenems to treat multidrug-resistant (MDR) Gram-negative bacteria (GNB) facilitates the wide dissemination of carbapenemase-producing carbapenem-resistant GNB. Colistin was reintroduced into clinical settings to manage these GNB infections. However, there is currently an increase in the dissemination of mobile colistin resistance (mcr)-producing colistin-resistant GNB isolates in clinical settings. The epidemiology of carbapenemases and mcr in Pretoria was evaluated. Methods: Clinical MDR GNB were collected and screened for carbapenemases and mcr using polymerase chain reaction (PCR); their antibiotic susceptibility profiles were elucidated using the Vitek^® 2 automated system (Biomerieux, France) and microbroth dilution (for colistin). Results and Discussion: A total of 306 isolates were collected; a majority of these were Klebsiella pneumoniae (n = 208) and were collected from males (n = 158). The isolates were retrieved from a variety of infection sites, including urine, blood cultures, and rectal swabs. The Vitek 2 system found that these isolates were largely resistant to β-lactams, where 217 (70.9%) had reduced susceptibility to at least one carbapenem (ertapenem, meropenem, or imipenem), and 81 isolates (26.5%) were resistant to colistin. PCR screening identified 201 (65.7%) isolates harboring carbapenemase genes consisting of bla_OXA-48 (170, 84.2%), bla_NDM (31, 15.4%), bla_IMP (5, 2%), bla_KPC (4, 1%), and bla_VIM (5, 2%). Furthermore, 14 bla_OXA-48-producing isolates were coharboring bla_VIM (2), bla_NDM (9), bla_KPC (1), and bla_IMP (2) genes. Only one isolate harbored the mobile colistin resistance (mcr)-1 gene, and this is the first report of an mcr-1-producing Acinetobacter baumannii isolate in South Africa. Conclusion: There is high endemicity of carbapenemase genes and a low prevalence of mcr genes in GNB, particularly in K. pneumoniae, in health care facilities in Pretoria and surrounding regions of South Africa. Significance: Health care facilities in Pretoria are becoming breeding grounds for MDR infections that threaten public health. Careful use of carbapenems and other antibiotics is necessary to prevent further escalation and outbreak of these MDR strains that can claim several lives.

Mobile Tigecycline Resistance: An Emerging Health Catastrophe Requiring Urgent One Health Global Intervention

Mobile tigecycline resistance (MTR) threatens the clinical efficacy of the salvage antibiotic, tigecycline (TIG) used in treating deadly infections in humans caused by superbugs (multidrug-, extensively drug-, and pandrug-resistant bacteria), including carbapenem- and colistin-resistant bacteria. Currently, non-mobile tet(X) and mobile plasmid-mediated transmissible tet(X) and resistance-nodulation-division (RND) efflux pump tmexCD-toprJ genes, conferring high-level TIG (HLT) resistance have been detected in humans, animals, and environmental ecosystems. Given the increasing rate of development and spread of plasmid-mediated resistance against the two last-resort antibiotics, colistin (COL) and TIG, there is a need to alert the global community on the emergence and spread of plasmid-mediated HLT resistance and the need for nations, especially developing countries, to increase their antimicrobial stewardship. Justifiably, MTR spread projects One Health ramifications and portends a monumental threat to global public and animal health, which could lead to outrageous health and economic impact due to limited options for therapy. To delve more into this very important subject matter, this current work will discuss why MTR is an emerging health catastrophe requiring urgent One Health global intervention, which has been constructed as follows: (a) antimicrobial activity of TIG; (b) mechanism of TIG resistance; (c) distribution, reservoirs, and traits of MTR gene-harboring isolates; (d) causes of MTR development; (e) possible MTR gene transfer mode and One Health implication; and (f) MTR spread and mitigating strategies.

Epidemiology and Traits of Mobile Colistin Resistance (mcr) Gene-Bearing Organisms from Horses

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.

Microbiological Characterisation of Community-Acquired Urinary Tract Infections in Bagamoyo, Tanzania: A Prospective Study

Urinary tract infections (UTIs) are among the most common infections in sub-Saharan Africa, but microbiological data to guide treatment decisions are limited. Hence, we investigated the bacterial aetiology and corresponding antimicrobial susceptibility patterns in outpatients with UTIs in Bagamoyo, Tanzania. Urine samples from symptomatic individuals were subjected to microbiological examinations for bacterial species identification using conventional methods and disc diffusion-based resistance testing. Subsequently, urine samples were transferred to Germany for confirmatory diagnostics using matrix-assisted laser desorption/ionization time-of-flight (MALDI-TOF) mass spectrometry and automated resistance testing. Overall, 104 out of 270 (38.5%) individuals had a positive urine culture and 119 putative pathogens were identified. The most frequently detected bacteria were Escherichia coli (23%), Klebsiella spp. (7%), Enterobacter cloacae complex (3%) and Staphylococcus aureus (2%). E. coli isolates showed high resistance against cotrimoxazole (76%), ampicillin (74%), piperacillin (74%) and fluoroquinolones (37%), but widespread susceptibility to meropenem (100%), fosfomycin (98%), piperacillin/tazobactam (97%) and amoxicillin/clavulanic acid (82%). The agreement between E. coli susceptibility testing results in Tanzania and Germany was ≥95%, except for piperacillin/tazobactam (89%) and ciprofloxacin (84%). Given the considerable resistance to frequently prescribed antibiotics, such as cotrimoxazole and fluoroquinolones, future research should explore the potential of oral alternatives (e.g., fosfomycin) for the treatment of UTIs in Tanzania.

Molecular Detection of Integrons, Colistin and β-lactamase Resistant Genes in Salmonella enterica Serovars Enteritidis and Typhimurium Isolated from Chickens and Rats Inhabiting Poultry Farms

The rapid growth of multidrug-resistant Salmonella is a global public health concern. The aim of this study was to detect integrons, colistin and β-lactamase resistance genes in Salmonella enteritidis and typhimurium. A total of 63 isolates of S. enteritidis (n = 18) and S. typhimurium (n = 45) from fecal samples of layers and rats at chicken farms were screened for antibiotic resistant genes. Conventional PCR was performed for the detection of integrons (classes 1, 2, and 3), colistin (mcr-1-5) and β-lactamase (bla_CTX-M, bla_CTX-M-1, bla_CTX-M-2, bla_CTX-M-9, bla_CTX-M-15, bla_TEM, bla_SHV, and bla_OXA) resistant genes. Of these isolates, 77% and 27% of S. typhimurium and S. enteritidis harboured the mcr-4 encoded gene for colistin, respectively. The prevalence of class 1 integrons for S. typhimurium and S. enteritidis was 100% for each serovar, while for class 2 integrons of S. typhimurium and S. enteritidis it was 49% and 33% respectively, while class 3 integron genes was not detected. Our study also detected high levels of β-lactamase encoding genes (bla gene), namely bla_CTX-M, bla_CTX-M-1, bla_CTX-M-9 and bla_TEM from both S. typhimurium and S. enteritidis. This, to our knowledge, is the first report of mcr-4 resistance gene detection in Salmonella serovars in South Africa. This study also highlights the importance of controlling rats at poultry farms in order to reduce the risk of transmission of antibiotic resistance to chickens and eventually to humans.