Contribution of NDM and OXA-type carbapenemases to carbapenem resistance in clinical Acinetobacter baumannii from Nigeria

Clinical Application of Metagenomic Next-Generation Sequencing (mNGS) in Patients with Early Pulmonary Infection After Liver Transplantation

Purpose

To examine the clinical utility of metagenomic next-generation sequencing (mNGS) in individuals with early pulmonary infection following liver transplantation.

Patients and Methods

mNGS and traditional detection results were retrospectively collected from 99 patients with pulmonary infection within one week following liver transplantation. These patients were admitted to the Department of Critical Liver Diseases at Beijing Friendship Hospital from February 2022 to February 2024, along with their general clinical data.

Results

mNGS exhibited a significantly higher detection rate than traditional methods (92.93% vs 54.55%, P < 0.05) and was more effective in identifying mixed infections (67.68% vs 14.81%, P < 0.05). mNGS identified 303 pathogens in 92 patients, with Enterococcus faecium, Pneumocystis jirovecii, and human herpesvirus types 5 and 7 being the most prevalent bacteria, fungi, and viruses. A total of 26 positive cases were identified through traditional culture methods (sputum and bronchoalveolar lavage fluid), with 18 cases consistent with mNGS detection results, representing 69.23% consistency. Among the three drug-resistant bacteria that showed positivity in mNGS and traditional culture, the presence of drug-resistance genes-mecA in Staphylococcus aureus; KPC-2, KPC-9, KPC-18, KPC-26, OXA27, OXA423 in Klebsiella pneumoniae; and OXA488 and NDM6 in Pseudomonas aeruginosa-reliably predicted drug-resistance phenotype. The treatment regimen for 76 of the 92 patients with positive mNGS relied on these results; 74 exhibited significant symptom improvement, yielding a 97.37% recovery rate. The overall prognosis was favorable.

Conclusion

mNGS offers rapid detection, a high positivity rate, insensitivity to antibiotics, and a superior ability to detect mixed infections in patients with early post-transplant pulmonary infections. Additionally, mNGS shows good consistency with traditional culture and can predict drug-resistant phenotypes to guide targeted antibiotic therapy for early-stage post-transplant pulmonary infection after liver transplantation. Patients whose antibiotic therapy is based on mNGS results have experienced decreased mortality rates and overall improved prognosis.

A systematic review and meta-analysis of carbapenem-resistant Enterobacteriaceae in West Africa

BACKGROUND

In Africa, the problem of carbapenem-resistant Enterobacteriaceae (CRE) is aggravated by many factors. This systematic review attempted to describe the current status of the molecular epidemiology of carbapenem resistance in West Africa (WA).

METHODS

Articles published from 16 West African countries on the molecular epidemiology of carbapenem resistance were reviewed. An extensive literature search was carried out in PubMed, Scopus, Web of Science, and African Journals Online (AJOL) using specific keywords. The meta-analysis and forest plots of major pathogens and carbapenem resistance genes were done using the Open Meta-Analyst, Task Order # 2 software. The data were analysed in binary random model effects by the DerSimonian-Laird method at a 95% confidence interval.

RESULTS

Of the 431 articles found in our initial search, 60 (13.92%) were considered suitable for inclusion. Only seven of the 16 West African countries formed part of the analysis, Nigeria (23/60), Ghana (19/60), Burkina Faso (7/60), Senegal (6/60), Benin (2/60), Mali (2/60), and Togo (1/60). Also, 80% (48/60) of the studies used clinical samples, 16.67% (10/60) used environmental samples, and 3.33% (2/60) used animal samples. The average prevalence was highest in Acinetobacter baumannii (18.6%; 95% CI = 14.0-24.6, I2 = 97.9%, p < 0.001), followed by Pseudomonas aeruginosa (6.5%; 95% CI = 3.1-13.4, I2 = 96.52%, p < 0.001), Klebsiella pneumoniae (5.8%; 95% CI = 4.2-7.9, I2 = 98.06%, p < 0.001) and Escherichia coli (4.1%; 95% CI = 2.2-7.7, I2 = 96.68%, p < 0.001). The average prevalence of the blaNDM gene was 10.6% (95% CI = 7.9-14.3, I2 = 98.2%, p < 0.001), followed by 3.9% (95% CI: 1.8-8.3, I2 = 96.73%, p < 0.001) for blaVIM and 3.1% (95% CI: 1.7-5.8, I2 = 91.69%, p < 0.001) for blaOXA-48.

CONCLUSION

In West Africa, K. pneumoniae, E. coli, A. baumannii, and P. aeruginosa are the main CRE with blaNDM, blaVIM, and blaOXA-48 being the predominant carbapenem resistance genes. In view of these results, ongoing CRE surveillance combined with antimicrobial stewardship improved, laboratory detection methods, and adherence to infection control practices will be needed to control the spread of CRE.

Outbreak of Multidrug-resistant Acinetobacter baumannii in a Tertiary Health Center from Northwestern Nigeria

Background

In spite of its global notoriety and WHO alarm, Acinetobacter baumannii is still an understudied critical-priority pathobiont in Nigeria. We characterized its antimicrobial susceptibility profile and resistance genes during an outbreak.

Materials and Methods

This cross-sectional study involved collection of patients' urine samples and swabs from unit staff's hands and ward environments for the identification of A. baumannii strains using standard morphologic and biochemical methods. The disk diffusion method was used to assess the antimicrobial susceptibility profile of the isolates with the production of extended-spectrum beta-lactamases (ESBLs) confirmed by the combined disk test screening method. Characterization of the resistance genes of the ESBL producers was carried out using polymerase chain reaction polymerase chain reaction technique.

Results

A.

total of eight (six clinical and two nonclinical) A. baumannii isolates were identified. The overall isolate susceptibility and resistance rates to all the antimicrobial agents was 56.3% (27/48) and 35.4% (17/48), respectively. Similarly, all (8/8; 100.00%) isolates were susceptible to meropenem and 75.0% (6/8) to ampicillin-sulbactam while 62.5% (5/8) were resistant to trimethoprim-sulfamethoxazole and 50.0% (4/8) to each of ciprofloxacin and ceftazidime. In addition, 37.5% (3/8) of the isolates were multidrug resistant (MDR) with nonclinical isolates exhibiting more antimicrobial resistance than their clinical counterparts (9/12%-75.0% vs. 8/36%-22.2%). Phenotypic detection and molecular characterization revealed three ESBL-producing isolates that each harbored blaSHV and blaTEM genes with blaCTX-M gene being absent.

Conclusion

MDR strains of A. baumannii harboring blaSHV and blaTEM genes were recovered from clinical and environmental sources during the outbreak, which was contained with preventive measures recommended.

Occurrence of New Delhi Metallo-Beta-Lactamase 1 Producing Enterococcus Species in Oghara Water Nexus: An Emerging Environmental Implications of Resistance Dynamics

Various members of the enteric bacteria in recent times are evolving diverse survival mechanisms for antibiotic therapy resulting in failure of treatment in infection and disease cases. The Enterococcus species are potential strains implicated in gastrointestinal tract infection and are recently evolving in the resistance mechanism. The study evaluates the occurrence of New Delhi Metallo-beta-lactamase 1 (NDM-1) amongst Enterococcus species using the phenotypic and genomic characterization of environmental strains in the Oghara water nexus. Presumptive isolates of Enterococcus species were retrieved from various sampled water sources and confirmed using polymerase chain reaction (PCR). Antibiotic susceptibility testing was conducted on confirmed isolates using Kirby-Bauer disk diffusion methods. The result reveals 63 genus isolates confirmed Enterococcus species, of which 42 (67%) were Enterococcus faecium, 15 (23%) were Enterococcus faecalis, and 6 (10%) were other Enterococcus species. Fourteen among the E. faecalis isolates show resistance to Ertapenem-EDTA, while 17 (44.8%) of the E. faecium show resistance to Ertapenem-EDTA to presumptively reveal their NDM-1 phenotype. The PCR detection of the NDM-1 gene further confirmed 23 (36.5%) isolates as positive genotypes amongst the isolates that previously showed presumptive NDM-1 phenotype. It was also observed that 10 (15.9%) of Enterococcus faecium members harbored the NDM-1 genotype, whereas 8 (12.7%) members of the Enterococcus faecalis harbored the NDM-1 genotype. The observation of such resistance determinants necessitates a call for the adroit application of relevant therapeutics in the management of related infections and an environmental health caution to prevent the spread of such resistance potential enteric bacteria pathogens.

Antimicrobial Resistance Rates and Surveillance in Sub-Saharan Africa: Where Are We Now?

Introduction

Although antimicrobials have traditionally been used to treat infections and improve health outcomes, resistance to commonly used antimicrobials has posed a major challenge. An estimated 700,000 deaths occur globally every year as a result of infections caused by antimicrobial-resistant pathogens. Antimicrobial resistance (AMR) also contributes directly to the decline in the global economy. In 2019, sub-Saharan Africa (SSA) had the highest mortality rate (23.5 deaths per 100,000) attributable to AMR compared to other regions.

Methods

We searched PubMed for articles relevant to AMR in pathogens in the WHO-GLASS list and in other infections of local importance in SSA. In this review, we focused on AMR rates and surveillance of AMR for these priority pathogens and some of the most encountered pathogens of public health significance. In addition, we reviewed the implementation of national action plans to mitigate against AMR in countries in SSA.

Results and Discussion

The SSA region is disproportionately affected by AMR, in part owing to the prevailing high levels of poverty, which result in a high burden of infectious diseases, poor regulation of antimicrobial use, and a lack of alternatives to ineffective antimicrobials. The global action plan as a strategy for prevention and combating AMR has been adopted by most countries, but fewer countries are able to fully implement country-specific action plans, and several challenges exist in many settings.

Conclusion

A concerted One Health approach will be required to ramp up implementation of action plans in the region. In addition to AMR surveillance, effective implementation of infection prevention and control, water, sanitation, and hygiene, and antimicrobial stewardship programs will be key cost-effective strategies in helping to tackle AMR.

Genetic support of carbapenemases: a One Health systematic review and meta-analysis of current trends in Africa

Antimicrobial resistance (AMR) is a public health threat globally. Carbapenems are β-lactam antibiotics used as last-resort agents for treating antibiotic-resistant infections. Mobile genetic elements (MGEs) play an important role in the dissemination and expression of antimicrobial resistance genes (ARGs), including the mobilization of ARGs within and between species. The presence of MGEs around carbapenem-hydrolyzing enzymes, called carbapenemases, in bacterial isolates in Africa is concerning. The association between MGEs and carbapenemases is described herein. Specific plasmid replicons, integrons, transposons, and insertion sequences were found flanking specific and different carbapenemases across the same and different clones and species isolated from humans, animals, and the environment. Notably, similar genetic contexts have been reported in non-African countries, supporting the importance of MGEs in driving the intra- and interclonal and species transmission of carbapenemases in Africa and globally. Technical and budgetary limitations remain challenges for epidemiological analysis of carbapenemases in Africa, as studies undertaken with whole-genome sequencing remained relatively few. Characterization of MGEs in antibiotic-resistant infections can deepen our understanding of carbapenemase epidemiology and facilitate the control of AMR in Africa. Investment in genomic epidemiology will facilitate faster clinical interventions and containment of outbreaks.

Molecular characterisation of the first New Delhi metallo-β-lactamase 1-producing Acinetobacter baumannii from Tanzania

BACKGROUND

We aimed to characterise the genetic determinants and context of two meropenem-resistant clinical isolates of Acinetobacter baumannii isolated from children hospitalised with bloodstream infections in Dar es Salaam, Tanzania.

METHODS

Antimicrobial susceptibility was determined by disc diffusion E-test and broth microdilution. Genomes were completed using a hybrid assembly of Illumina and Oxford Nanopore Technologies sequencing reads and characterisation of the genetic context of resistance genes, multi-locus sequence types (STs) and phylogenetic analysis was determined bioinformatically.

RESULTS

Twelve A. baumannii were isolated from 2226 blood cultures, two of which were meropenem-resistant. The two meropenem-resistant isolates, belonging to distinct STs, ST374 and ST239, were found to harbour blaNDM-1, which was chromosomally located in isolate DT0544 and plasmid-located in isolate DT01139. The genetic environment of blaNDM-1 shows the association of insertion sequence ISAba125 with blaNDM-1 in both isolates. Both isolates also harboured genes conferring resistance to other β-lactams, aminoglycosides and cotrimoxazole.

CONCLUSIONS

This is the first report of New Delhi metallo-β-lactamase-producing isolates of A. baumannii from Tanzania. The genetic context of blaNDM-1 provides further evidence of the importance of ISAba125 in the spread of blaNDM-1 in A. baumannii. Local surveillance should be strengthened to keep clinicians updated on the incidence of these and other multidrug-resistant and difficult-to-treat bacteria.