Establishing a national reference laboratory for antimicrobial resistance using a whole-genome sequencing framework: Nigeria's experience.

Whole-genome sequencing (WGS) is finding important applications in the surveillance of antimicrobial resistance (AMR), providing the most granular data and broadening the scope of niches and locations that can be surveilled. A common but often overlooked application of WGS is to replace or augment reference laboratory services for AMR surveillance. WGS has supplanted traditional strain subtyping in many comprehensive reference laboratories and is now the gold standard for rapidly ruling isolates into or out of suspected outbreak clusters. These and other properties give WGS the potential to serve in AMR reference functioning where a reference laboratory did not hitherto exist. In this perspective, we describe how we have employed a WGS approach, and an academic-public health system collaboration, to provide AMR reference laboratory services in Nigeria, as a model for leapfrogging to national AMR surveillance.

Clones and Clusters of Antimicrobial-Resistant Klebsiella From Southwestern Nigeria.

BACKGROUND: Klebsiella pneumoniae is a World Health Organization high-priority antibiotic-resistant pathogen. However, little is known about Klebsiella lineages circulating in Nigeria. METHODS: We performed whole-genome sequencing (WGS) of 141 Klebsiella isolated between 2016 and 2018 from clinical specimens at 3 antimicrobial-resistance (AMR) sentinel surveillance tertiary hospitals in southwestern Nigeria. We conducted in silico multilocus sequence typing; AMR gene, virulence gene, plasmid, and K and O loci profiling; as well as phylogenetic analyses, using publicly available tools and Nextflow pipelines. RESULTS: Phylogenetic analysis revealed that the majority of the 134 K. pneumoniae and 5 K. quasipneumoniae isolates from Nigeria characterized are closely related to globally disseminated multidrug-resistant clones. Of the 39 K. pneumoniae sequence types (STs) identified, the most common were ST307 (15%), ST5241 (12%), ST15 (~9%), and ST25 (~6%). ST5241, 1 of 10 novel STs detected, is a single locus variant of ST636 carrying dfrA14, tetD, qnrS, and oqxAB resistance genes. The extended-spectrum ß-lactamase (ESBL) gene blaCTX_M-15 was seen in 72% of K. pneumoniae genomes, while 8% encoded a carbapenemase. No isolate carried a combination of carbapenemase-producing genes. Four likely outbreak clusters from 1 facility, within STs 17, 25, 307, and 5241, were ESBL but not carbapenemase-bearing clones. CONCLUSIONS: This study uncovered known and novel K. pneumoniae lineages circulating in 3 hospitals in Southwest Nigeria that include multidrug-resistant ESBL producers. Carbapenemase-producing isolates remain uncommon. WGS retrospectively identified outbreak clusters, pointing to the value of genomic approaches in AMR surveillance for improving infection prevention and control in Nigerian hospitals.

Occult Hepatitis B virus infection in previously screened, blood donors in Ile-Ife, Nigeria: implications for blood transfusion and stem cell transplantation.

BACKGROUND: Hepatitis B virus (HBV) transmission through blood transfusion is reduced by screening for hepatitis B surface antigen (HBsAg). However this method cannot detect the presence of occult hepatitis B virus infection. This study sought to determine the prevalence of occult hepatitis B virus infection among blood donors in Ile-Ife, Nigeria. For the first time in Nigeria we employed an automated real-time PCR- method to investigate the prevalence of occult HBV in blood donors. METHODS: Blood donors screened with HBsAg immunochromatographic rapid test kits at the blood transfusion units of two hospitals and found to be negative were recruited into the study. Questionnaires to elicit risk factors for HBV infection were administered and then 10 ml of blood was collected from each donor. Plasma samples obtained from these HBsAg negative blood donors were screened again for HBsAg using an enzyme-linked immunosorbent assay (ELISA) method, and those found negative were screened for the presence of total antibody to the HBV core antigen (anti-HBc) using ELISA method. Those positive to anti-HBc were then tested for HBV DNA, using an automated real-time PCR method. RESULTS: Five hundred and seven blood donors found HBsAg negative by immunochromatographic rapid test kits at both blood transfusion units, were tested for HBsAg using ELISA and 5 (1 %) were HBsAg positive. The 502 found negative were tested for anti-HBc and 354 (70.5 %) were found positive implying previous exposure to HBV and 19 (5.4 %) of the 354 anti-HBc positive had HBV DNA signifying occult HBV infection. No risk factors were found to be associated with the presence of HBV DNA among those who tested positive. CONCLUSION: Occult HBV infection exists in blood donors in Ile-Ife, Nigeria and the use of HBsAg alone for screening prospective donors will not eliminate the risk of HBV transmission in blood transfusion or stem cell transplantation.

Diarrhoeagenic Escherichia coli in mother-child Pairs in Ile-Ife, South Western Nigeria.

BACKGROUND: Diarrhoeagenic Escherichia coli (DEC) pathotypes are among the most common bacterial causes of morbidity and mortality in young children. These pathogens are not sought routinely and capacity for their detection is limited in Africa. We investigated the distribution and dissemination of DEC in 126 children paired with their mothers in a Nigerian community. METHODS: A total of 861 E. coli were isolated from 126 children with diarrhoea and their mothers. Antimicrobial susceptibility of each isolate was determined by Kirby-Bauer disc diffusion technique. All the isolates were screened for DEC markers by multiplex PCR. Genetic relatedness of DEC strains was determined by flagellin typing and Insertion element 3 (IS3)-based PCR. RESULTS: DEC were identified from 35.7% of individuals with the most common pathotype being shiga toxin-producing E. coli (42, 16.7%). Identical pathotypes were found in 13 (10.3%) of the mother-child pairs and in three of these strains from mothers and their children showed identical genetic signatures. Over 90% of DEC isolates were resistant to ampicillin, sulphonamide, tetracycline, streptomycin or trimethoprim, but only 9 (7.2%) were ciprofloxacin resistant CONCLUSION: The data suggest that healthy mothers are asymptomatic reservoirs of multiply-resistant strains that are pathogenic in their children and there are instances in which identical strains are found in mother-child pairs.

National health insurance scheme improves access and optimization of antimicrobial use in the Obafemi Awolowo University Teaching Hospitals Complex, Ile-Ife, Nigeria.

BACKGROUND: Nigeria instituted the National Health Insurance Scheme (NHIS) for universal health coverage. This study compared the NHIS and out-of-pocket (OOP) antibiotic prescribing with the World Health Organization (WHO) optimal values. METHODS: A total of 2190 prescription forms from the NHIS and OOP were included in this study conducted at Obafemi Awolowo University Teaching Hospitals Complex, Nigeria from January 2021 to December 2022 and analysed using WHO drug prescribing guidelines. RESULTS: The average number of drugs per encounter was higher in the NHIS prescribing (χ2=58.956, p=0.00) than in OOP prescribing. The percentage of encounters with an antibiotic prescribed is higher in NHIS prescribing (χ2=46.034, p=0.000) than in OOP prescribing. The percentage of parenteral antibiotic prescribing is higher in OOP prescribing (χ2=25.413, p=0.000) than in NHIS prescribing. The percentage of antibiotic prescribed from the National Essential Medicine List is higher in NHIS prescribing (χ2=8.227, p=0.000) as well as the antibiotics prescribed from the Access category of the WHO Access, Watch and Reserve (AWaRe) Classification of antibiotics (χ2=23.946, p=0.000) when compared with OOP prescribing. CONCLUSIONS: Prescribing indicators show better performances with NHIS antibiotic prescribing and are closer to the WHO-recommended optimal values than in OPP prescribing. Hence NHIS prescribing can be an easy target for hospital antibiotic stewardship intervention for optimal antibiotic prescribing.

Serogroup distribution of Shigella in Ile-Ife, southwest Nigeria.

BACKGROUND: Shigellosis is endemic throughout the world and Shigella spp. is among the most common pathogens responsible for bacterial diarrhoeal diseases. Death attributed to shigellosis is common in developing countries, where affected populations are immunologically compromised due to poor nutrition and background infections. AIM: To investigate the serogroup distribution of Shigella spp. recovered from clinically diagnosed cases of gastroenteritis and acute diarrhoea among children (0-5 years) in Ile-Ife, southwest Nigeria between September 2003 and September 2006. METHODS: The isolates were identified and characterized biochemically and serologically. RESULTS: Out of 102 Shigella isolates identified, 45 (44%) were S. flexneri, 26 (25%) were S. dysenteriae, 19 (19%) were S. boydii, 6 (6%) were S. sonnei and 6 (6%) were untypable strains. CONCLUSIONS: We conclude that Shigella serogroups can be considered an important aetiological agent of acute diarrhoea and mortality among children in Ile-Ife, southwest Nigeria.

Clinical and bacteriological profiles of neonatal sepsis in a tertiary hospital, south-western Nigeria.

Introduction: Antibiotic-resistant bacteria complicate treatment options in neonatal sepsis, especially in developing countries. This study determined the epidemiology and bacteriological characteristics of neonatal sepsis at a tertiary hospital, in southwest Nigeria. Methods: This was a cross-sectional study from December 2017 to April 2019 among admitted babies with clinical neonatal sepsis. Blood culture was performed by semi-automated system, sepsis biomarker assay (serum procalcitonin) by a semi-quantitative kit while proforma was used to capture clinico-demographic data. Bacterial identification, antibiotic susceptibility patterns, determination of genetic elements mediating resistance, were performed by standard methods and polymerase chain reaction protocols, respectively. Quantitative data were expressed as frequencies, mean; bivariate and multivariate analyses were performed by Chi-square or Fishers' exact test and logistic regression. Results: Of the 192 cases of neonatal sepsis enrolled, 42.7% (82/192) were blood culture positive. Factors associated with blood culture positivity included respiratory rate ≥60 bpm (60/82; p<0.03), lethargy/unconsciousness (59/82; FE=7.76; p<0.001), grunting respiration (54/82; p=0.04), meconium passage before birth (17/82; p=0.03) and prolonged rupture of membranes ≥24 hours (50/82; FE=6.90; p=0.01). On the other hand, mortality in the neonates was associated with elevated serum procalcitonin assay (>0.5 ng/mL) χ2=13.58; p=0.03] and Gram-negative bacteremia (χ2=24.64; p<0.001). The most common bacterial isolates were Staphylococcus aureus (42/82), coagulase-negative Staphylococcus spp. (17/82), Enterobacter spp. (8/82), and Acinetobacter spp. (6/82). Methicillin resistance was present in 85.7% (36/42) of Staphylococcus aureus and 52.9% (9/17) of coagulase-negative Staphylococcus, while extended-spectrum beta-lactamase (ESBL) and AmpC enzymes were present in (21.1%; 4/19) of the Gram-negative bacilli. Conclusions: Almost half of the cases of clinically diagnosed neonatal sepsis have bacterial etiologic confirmation of sepsis. Gram-negative bacteremia and high serum procalcitonin predict mortality in neonatal sepsis. There was high resistance to common antibiotics for the treatment of neonatal sepsis in our settings.

High Genetic Diversity of Carbapenem-Resistant Acinetobacter baumannii Isolates Recovered in Nigerian Hospitals in 2016 to 2020.

Acinetobacter baumannii causes difficult-to-treat infections mostly among immunocompromised patients. Clinically relevant A. baumannii lineages and their carbapenem resistance mechanisms are sparsely described in Nigeria. This study aimed to characterize the diversity and genetic mechanisms of carbapenem resistance among A. baumannii strains isolated from hospitals in southwestern Nigeria. We sequenced the genomes of all A. baumannii isolates submitted to Nigeria's antimicrobial resistance surveillance reference laboratory between 2016 and 2020 on an Illumina platform and performed in silico genomic characterization. Selected strains were sequenced using the Oxford Nanopore technology to characterize the genetic context of carbapenem resistance genes. The 86 A. baumannii isolates were phylogenetically diverse and belonged to 35 distinct Oxford sequence types (oxfSTs), 16 of which were novel, and 28 Institut Pasteur STs (pasSTs). Thirty-eight (44.2%) isolates belonged to none of the known international clones (ICs). Over 50% of the isolates were phenotypically resistant to 10 of 12 tested antimicrobials. The majority (n = 54) of the isolates were carbapenem resistant, particularly the IC7 (pasST25; 100%) and IC9 (pasST85; >91.7%) strains. blaOXA-23 (34.9%) and blaNDM-1 (27.9%) were the most common carbapenem resistance genes detected. All blaOXA-23 genes were carried on Tn2006 or Tn2006-like transposons. Our findings suggest that a 10-kb Tn125 composite transposon is the primary means of blaNDM-1 dissemination. Our findings highlight an increase in blaNDM-1 prevalence and the widespread transposon-facilitated dissemination of carbapenemase genes in diverse A. baumannii lineages in southwestern Nigeria. We make the case for improving surveillance of these pathogens in Nigeria and other understudied settings. IMPORTANCE Acinetobacter baumannii bacteria are increasingly clinically relevant due to their propensity to harbor genes conferring resistance to multiple antimicrobials, as well as their ability to persist and disseminate in hospital environments and cause difficult-to-treat nosocomial infections. Little is known about the molecular epidemiology and antimicrobial resistance profiles of these organisms in Nigeria, largely due to limited capacity for their isolation, identification, and antimicrobial susceptibility testing. Our study characterized the diversity and antimicrobial resistance profiles of clinical A. baumannii in southwestern Nigeria using whole-genome sequencing. We also identified the key genetic elements facilitating the dissemination of carbapenem resistance genes within this species. This study provides key insights into the clinical burden and population dynamics of A. baumannii in hospitals in Nigeria and highlights the importance of routine whole-genome sequencing-based surveillance of this and other previously understudied pathogens in Nigeria and other similar settings.

National action plan on antimicrobial resistance: An evaluation of implementation in the World Health Organization Africa region.

In line with global instruments, within the last five years, two-thirds of all countries in the WHO Africa Region (WHO AFR) have developed a National Action Plan (NAP) on Antimicrobial Resistance (AMR). We sought to evaluate progress made across the countries implementing NAP for effective response to AMR. A semi-structured survey tool was administered to obtain information from national focal persons on the implementation of strategic elements of NAP on AMR. This was followed by a Lessons Learnt Workshop in June 2019 at Douala, Cameroon, where focal persons made presentations on the country's progress. Later, a desktop review of the LLW report and other key documents was conducted. Countries in WHO AFR that have set up a national surveillance system and are enrolled into the WHO global antimicrobial resistance surveillance system have progressively increased to 30 (of 47 countries), of which 15 are already submitting surveillance data. Of the 20 countries at the Lessons Learnt Workshop, 14 have infection prevention and control (IPC) policies and functional healthcare facility IPC programs, 15 participate in the commemoration of the annual world hand hygiene days. Although almost all countries surveyed have national standard treatment guidelines, only five have incorporated the WHO AWaRe classification into the national essential medicines list. Fourteen of 20 countries have established an active/functional national secretariat/coordinating center for AMR. Discernible progress is being made on the implementation of NAP in WHO AFR region. Gaps identified in the strategic elements of action plans need to be filled for effective AMR control.

Implementation of an antimicrobial stewardship programme in three regional hospitals in the south-east of Liberia: lessons learned.

Background: Antimicrobial stewardship (AMS) programmes can improve the use of antimicrobial agents. However, there is limited experience in the implementation of such programmes in low- and middle-income countries (LMICs). Objectives: To assess the effect of AMS measures in south-east Liberia on the quality of antimicrobial use in three regional hospitals. Methods: A bundle of three measures (local treatment guideline, training and regular AMS ward rounds) was implemented and quality indicators of antimicrobial use (i.e. correct compounds, dosage and duration) were assessed in a case series before and after AMS ward rounds. Primary endpoints were (i) adherence to the local treatment guideline; (ii) completeness of the microbiological diagnostics (according to the treatment guideline); and (iii) clinical outcome. The secondary endpoint was reduction in ceftriaxone use. Results: The majority of patients had skin and soft tissue infections (n = 108) followed by surgical site infections (n = 72), pneumonia (n = 64), urinary tract infection (n = 48) and meningitis (n = 18). After the AMS ward rounds, adherence to the local guideline improved for the selection of antimicrobial agents (from 34.5% to 61.0%, P < 0.0005), dosage (from 15.2% to 36.5%, P < 0.0005) and duration (from 13.2% to 31.0%, P < 0.0005). In total, 79.7% of patients (247/310) had samples sent for microbiological analysis. Overall, 92.3% of patients improved on Day 3 (286/310). The proportion of patients receiving ceftriaxone was significantly reduced after the AMS ward rounds from 51.3% to 14.2% (P < 0.0005). Conclusions: AMS measures can improve the quality of antimicrobial use in LMICs. However, long-term engagement is necessary to make AMS programmes in LMICs sustainable.

Genomic characterization of invasive typhoidal and non-typhoidal Salmonella in southwestern Nigeria.

BACKGROUND: Salmonellosis causes significant morbidity and mortality in Africa. Information on lineages of invasive Salmonella circulating in Nigeria is sparse. METHODS: Salmonella enterica isolated from blood (n = 60) and cerebrospinal fluid (CSF, n = 3) between 2016 and 2020 from five tertiary hospitals in southwest Nigeria were antimicrobial susceptibility-tested and Illumina-sequenced. Genomes were analysed using publicly-available bioinformatic tools. RESULTS: Isolates and sequence types (STs) from blood were S. Typhi [ST1, n = 1 and ST2, n = 43] and invasive non-typhoidal Salmonella (iNTS) (S. Enteritidis [ST11, n = 7], S. Durham [ST10, n = 2], S. Rissen [ST8756, n = 2], S. Chester [ST2063, n = 1], S. Dublin [ST10, n = 1], S. Infantis [ST603, n = 1], S. Telelkebir [ST8757, n = 1] and S. Typhimurium [ST313, n = 1]). S. Typhi ST2 (n = 2) and S. Adabraka ST8757 (n = 1) were recovered from CSF. Most S. Typhi belonged to genotype 3.1.1 (n = 44), carried an IncY plasmid, had several antibiotic resistance genes (ARGs) including blaTEM-1 (n = 38), aph(6)-Id (n = 32), tet(A) (n = 33), sul2 (n = 32), dfrA14 (n = 30) as well as quinolone resistance-conferring gyrA_S83Y single-nucleotide polymorphisms (n = 37). All S. Enteritidis harboured aph(3")-Ib, blaTEM-1, catA1, dfrA7, sul1, sul2, tet(B) genes, and a single ARG, qnrB19, was detected in S. Telelkebir. Typhoidal toxins cdtB, pltA and pltB were detected in S. Typhi, Rissen, Chester, and Telelkebir. CONCLUSION: Most invasive salmonelloses in southwest Nigeria are vaccine-preventable infections due to multidrug-resistant, West African dominant S. Typhi lineage 3.1.1. Invasive NTS serovars, including some harbouring typhoidal toxin or resistance genes, represented a third of the isolates emphasizing the need for better diagnosis and surveillance.

Multicentre study of the burden of multidrug-resistant bacteria in the aetiology of infected diabetic foot ulcers.

BACKGROUND: Infected diabetic foot ulcer (IDFU) is a public health issue and the leading cause of non-traumatic limb amputation. Very few published data on IDFU exist in most West African countries. OBJECTIVE: The study investigated the aetiology and antibacterial drug resistance burden of IDFU in tertiary hospitals in Osun state, Nigeria, between July 2016 and April 2017. METHODS: Isolates were cultured from tissue biopsies or aspirates collected from patients with IDFU. Bacterial identification, antibiotic susceptibility testing and phenotypic detection of extended-spectrum beta-lactamase and carbapenemase production were done by established protocols. Specific resistance genes were detected by polymerase chain reaction. RESULTS: There were 218 microorganisms isolated from 93 IDFUs, comprising 129 (59.2%) Gram-negative bacilli (GNB), 59 (27.1%) Gram-positive cocci and 29 (13.3%) anaerobic bacteria. The top five facultative anaerobic bacteria isolated were: Staphylococcus aureus (34; 15.6%), Escherichia coli (23; 10.6%), Pseudomonas aeruginosa (20; 9.2%), Klebsiella pneumoniae (19; 8.7%) and Citrobacter spp. (19; 8.7%). The most common anaerobes were Bacteroides spp. (7; 3.2%) and Peptostreptococcus anaerobius (6; 2.8%). Seventy-four IDFUs (80%) were infected by multidrug-resistant bacteria, predominantly methicillin-resistant S. aureus and GNB producing extended-spectrum ß-lactamases, mainly of the CTX-M variety. Only 4 (3.1%) GNB produced carbapenemases encoded predominantly by bla VIM. Factors associated with presence of multidrug-resistant bacteria were peripheral neuropathy (adjusted odds ratio [AOR] = 4.05, p = 0.04) and duration of foot infection of more than 1 month (AOR = 7.63, p = 0.02). CONCLUSION: Multidrug-resistant facultative anaerobic bacteria are overrepresented as agents of IDFU. A relatively low proportion of the aetiological agents were anaerobic bacteria.

Antimicrobial use among hospitalized patients: A multi-center, point prevalence survey across public healthcare facilities, Osun State, Nigeria.

INTRODUCTION: In order to inform sub-national action plan for control of antimicrobial resistance (AMR) and benchmark interventions to improve antibiotic use, it is essential to define situations on antibiotic use using standardized tools. We sought to assess quality of antimicrobial prescription across all government healthcare facilities with capacities for in-patient care in the first of the 36 states in Nigeria as part of ongoing state-wide situation analysis on AMR. METHODS: A survey was conducted between 10-27 June 2019 using the WHO methodology for point prevalence survey on antibiotic use in hospitals. Data was collected from hospital administrators and records of hospitalized patients. Data analysis was done using Microsoft Excel 2010 (Redmond Washington). RESULTS: Prevalence of antibiotic use amongst all 321 included patients was 76.6% (246/321). Of all indications recorded, the highest was surgical prophylaxis (96/260, 36.9%) for which there were multiple doses beyond 24 hours in almost all cases (91/96, 94.8%). The largest volume of prescribing took place in the surgical wards, and the most common prescriptions were metronidazole (142/564, 25.2%), cefuroxime (104/564, 18.4%), and ceftriaxone (77/564, 13.7%). Overall, 46.3% of the antibiotics used belong to Access group, 53.5% to watch and only 0.2% to Reserve. Treatment in almost all instances 544/563 (96.6%) was empiric. CONCLUSIONS: The majority of patients received multiple antibiotics mostly without compliance to guidelines. There was low prescribing of Access antibiotics and excessive use of antibiotics in the Watch group. Antibiotics were used most commonly for surgical prophylaxis but inappropriately. Inappropriate use of antibiotics in this study underscores the crucial need for an action plan incorporating antimicrobial stewardship.

Healthcare-associated infections and compliance of hand hygiene among healthcare workers in a tertiary health facility, southwest Nigeria.

INTRODUCTION: Healthcare-associated infections (HAIs) are threats in healthcare settings contributing to increased morbidity, mortality and antimicrobial resistance worldwide. Hand hygiene (HH) is the simplest and most important single intervention to reduce HAIs. AIMS/OBJECTIVES: This study sought to determine rates of HAIs as well as compliance of HH among healthcare workers (HCWs) in Obafemi Awolowo University Teaching Hospitals Complex (OAUTHC). METHODS: A cross-sectional study was conducted among 227 HCWs (59 doctors, 129 nurses and 39 ward attendants) selected by multistage sampling across 10 hospital wards. Electronic interviewer-administered questionnaire, HH compliance checklist and point prevalence of HAI were done using World Health Organization and Centers for Disease Control and Prevention toolkits, respectively. RESULTS: Only 20.33% (n = 12) of doctors, 3.88% (n = 5) of nurses and 2.56% (n = 1) of ward attendants had good knowledge of HH (χ2 = 22.22, P value = 0.01). Among doctors, 11.86% (n = 7), 6.98% (n = 9) of nurses and 2.56% (n = 1) of ward attendants had positive perception towards HH (χ2 = 7.87, P value = 0.25). Of the 174 opportunities for HH observed, compliance rates were 42.37%, 55.81% and 68.97% among doctors, nurses and ward attendants, respectively. Point prevalence of HAI was 16.38%. DISCUSSION: Good knowledge and positive perception about HH were uncommon among doctors, nurses and ward attendants. However, ward attendants had the highest compliance to HH. There was a high prevalence of HAIs in this institution.

A large self-transmissible resistance plasmid from Nigeria contains genes that ameliorate a carrying cost.

Antimicrobial resistance is rapidly expanding, in a large part due to mobile genetic elements. We screened 94 fecal fluoroquinolone-resistant Escherichia coli isolates from Nigeria for six plasmid-mediated quinolone resistance (PMQR) genes. Sixteen isolates harbored at least one of the PMQR genes and four were positive for aac-6-Ib-cr. In one strain, aac-6-Ib-cr was mapped to a 125 Kb self-transmissible IncFII plasmid, pMB2, which also bears blaCTX-M-15, seven other functional resistance genes and multiple resistance pseudogenes. Laboratory strains carrying pMB2 grew faster than isogenic strains lacking the plasmid in both rich and minimal media. We excised a 32 Kb fragment containing transporter genes and several open-reading frames of unknown function. The resulting 93 Kb mini-plasmid conferred slower growth rates and lower fitness than wildtype pMB2. Trans-complementing the deletion with the cloned sitABCD genes confirmed that they accounted for the growth advantage conferred by pMB2 in iron-depleted media. pMB2 is a large plasmid with a flexible resistance region that contains loci that can account for evolutionary success in the absence of antimicrobials. Ancillary functions conferred by resistance plasmids can mediate their retention and transmissibility, worsening the trajectory for antimicrobial resistance and potentially circumventing efforts to contain resistance through restricted use.

A systematic review of healthcare-associated infections in Africa: An antimicrobial resistance perspective.

BACKGROUND: Healthcare-associated infection (HCAI) is a global health challenge, not only as an issue of patient safety but also as a major driver of antimicrobial resistance (AMR). It is a major cause of morbidity and mortality with economic consequences. OBJECTIVE: This review provides an update on the occurrence of HCAI, as well as the contribution of emerging AMR on healthcare delivery in Africa. METHODS: We searched PubMed, Cochrane database, African Journals Online and Google Scholar for relevant articles on HCAI in Africa between 2010 and 2017. Preferred reporting items of systematic reviews and meta-analyses guidelines were followed for selection. Thirty-five eligible articles were considered for the qualitative synthesis. RESULTS: Of the 35 eligible articles, more than half (n = 21, 60%) were from East Africa. Klebsiella spp., Staphylococcus aureus, Escherichia coli and Pseudomonas spp. were the common pathogens reported in bloodstream infection, (catheter-associated) urinary tract infection, surgical site infection and healthcare-associated pneumonia. Among these various subtypes of HCAI, methicillin-resistant S. aureus (3.9% - 56.8%) and extended-spectrum beta-lactamase producing Gram-negative bacilli (1.9% - 53.0%) were the most reported antimicrobial resistant pathogens. CONCLUSION: This review shows a paucity of HCAI surveillance in Africa and an emergence of AMR priority pathogens. Hence, there is a need for a coordinated national and regional surveillance of both HCAI and AMR in Africa.

Antimicrobial resistance of Vibrio cholerae from sub-Saharan Africa: A systematic review.

BACKGROUND: The World Health Assembly adopted the Global Action Plan on Antimicrobial Resistance, which includes improving the knowledge base through surveillance and research. Noteworthily, the World Health Organization has advocated a Global Antimicrobial Resistance Surveillance System to address the plan's surveillance objective, with most African countries enrolling in or after 2017. AIM: The aim of this article was to review prior data on antimicrobial resistance of Vibrio cholerae from sub-Saharan Africa with a view for future control and intervention strategies. METHODS: We used the Preferred Reporting Items for Systematic Review and Meta-Analysis (or 'PRISMA') guidelines to search the PubMed and African Journals Online databases, as well as additional articles provided by the Nigeria Centre for Disease Control, for articles reporting on the antibiotic susceptibility of V. cholerae between January 2000 and December 2017. RESULTS: We identified 340 publications, of which only 25 (reporting from 16 countries within the sub-Saharan African region) were eligible. The majority (20; 80.0%) of the cholera toxigenic V. cholerae isolates were of the serogroup O1 of the El Tor biotype with Ogawa and Inaba serotypes predominating. Resistance was predominantly documented to trimethoprim-sulphamethoxazole (50% of the studies), ampicillin (43.3% of the studies), chloramphenicol (43.3% of the studies) and streptomycin (30% of the studies). Resistance mechanisms were reported in 40% of the studies. CONCLUSION: Our results demonstrate a documented antimicrobial resistance of V. cholerae to multiple antibiotic classes, including cell wall active agents and antimetabolites with evidence of phenotypic/genotypic resistance to fluoroquinolones.

Correction: Classes 1 and 2 integrons in faecal Escherichia coli strains isolated from mother-child pairs in Nigeria.

[This corrects the article DOI: 10.1371/journal.pone.0183383.].

Classes 1 and 2 integrons in faecal Escherichia coli strains isolated from mother-child pairs in Nigeria.

BACKGROUND: Antimicrobial resistance among enteric bacteria in Africa is increasingly mediated by integrons on horizontally acquired genetic elements. There have been recent reports of such elements in invasive pathogens across Africa, but very little is known about the faecal reservoir of integron-borne genes. METHODS AND FINDINGS: We screened 1098 faecal Escherichia coli isolates from 134 mother-child pairs for integron cassettes by PCR using primers that anneal to the 5' and 3' conserved ends of the cassette regions and for plasmid replicons. Genetic relatedness of isolates was determined by flagellin and multi-locus sequence typing. Integron cassettes were amplified in 410 (37.5%) isolates and were significantly associated with resistance to trimethoprim and multiple resistance. Ten cassette combinations were found in class 1 and two in class 2 integrons. The most common class 1 cassette configurations were single aadA1 (23.4%), dfrA7 (18.3%) and dfrA5 (14.4%). Class 2 cassette configurations were all either dfrA1-satI-aadA1 (n = 31, 7.6%) or dfrA1-satI (n = 13, 3.2%). A dfr cassette was detected in 294 (31.1%) of trimethoprim resistant strains and an aadA cassette in 242 (23%) of streptomycin resistant strains. Strains bearing integrons carried a wide range of plasmid replicons of which FIB/Y (n = 169; 41.2%) was the most frequently detected. Nine isolates from five different individuals carried the dfrA17-aadA5-bearing ST69 clonal group A (CGA). The same integron cassette combination was identified from multiple distinct isolates within the same host and between four mother-child pairs. CONCLUSIONS: Integrons are important determinants of resistance in faecal E. coli. Plasmids in integron-containing strains may contribute to dispersing resistance genes. There is a need for improved surveillance for resistance and its mechanisms of dissemination and persistence and mobility of resistance genes in the community and clinical settings.