Comparative evaluation of SARS-CoV-2 serological tests shows significant variability in performance across different years of infection and between the tests.

Introduction: While the global COVID-19 pandemic is slowly coming under control, current efforts are focused on understanding the epidemiology of endemic SARS-CoV-2. The tool of choice for doing so remains serological tests that detect SARS-CoV-2 induced antibodies. However, the performance of these tests should be evaluated to ensure they comply with the specific performance criteria desired by each country that they are used in. Methods: Here, we use pre-COVID-19 plasma and plasma from SARS-CoV-2-infected individuals collected in 2020, 2021 and 2022 to evaluate the performance of two commercial Rapid Lateral Flow (RLF) tests (the PANBIO™ COVID-19 IgG/IgM rapid test and the LABNOVATION™ COVID-19 (SARS-CoV-2) IgG/IgM rapid test) and one commercial ELISA test (the PLATELIA™ SARS-CoV-2 total Ab). Results: We find that whereas the specificity of the two RLF tests is ≥ 95%, it was 91% for the ELISA tests. However, at 14 days post-COVID-19 date of diagnosis (DoD), only the ELISA test constantly achieved a sensitivity of ≥80% over all the three years. In addition, the rate of detection of the two RLF tests varied across the years with a sensitivity ranging from <80% in 2021 to >80% in 2022. More importantly the capacity of these two RLF tests to detect IgG antibodies decreased with time. On the contrary, the sensitivity of the ELISA test was still above 80% more than six months post DoD. Conclusion: We recommend that sero-epidemiological surveys focused on testing antibodies should not rely on performances reported by the assay manufacturers. They should include a formal evaluation of the selected assays to ensure its limitations and strengths conform with the data-accuracy requirements of the surveys.

Botanicals and phytochemicals from the bark of Hypericum roeperianum (Hypericaceae) had strong antibacterial activity and showed synergistic effects with antibiotics against multidrug-resistant bacteria expressing active efflux pumps.

ETHNOPHARMACOLOGICAL RELEVANCE: Infections due to multidrug-resistant (MDR) bacteria constitute a real problem in the public health worldwide. Hypericum roeperianum Schimp. ex A. Rich (Hypericaceae) is used traditionally for treatment of various ailments such as abdominal pains, constipation, diarrhea, indigestion, nausea, and bacterial diseases. AIM OF THE STUDY: This study was aimed at investigating the antibacterial and antibiotic-modifying activity of the crude methanol extracts (HRB), ethyl-acetate soluble fraction (HRBa), residual material (HRBb), and 11 compounds from the bark of Hypericum roeperianum against multi-drug resistant (MDR) bacteria expressing active efflux pumps. MATERIALS AND METHODS: The antibacterial activity, the efflux pump effect using the efflux pump inhibitor (EPI), phenylalanine-arginine-ß-naphthylamide (PAßN), as well as the antibiotic-modifying activity of samples were determined using the broth micro-dilution method. Spectrophotometric methods were used to evaluate the effects of HRB and 8,8-bis(dihydroconiferyl) diferulate (11) on bacterial growth, and bacterial membrane damage, whereas follow-up of the acidification of the bacterial culture was used to study their effects on bacteria proton-ATPase pumps. RESULTS: The crude extract (HRB), HRBa, and HRBb had selective antibacterial activity with MICs ranging from 16 to 512 µg/mL. Phytochemical 11 displayed the best antibacterial activity (0.5 ≤ MIC ≤ 2 µg/mL). The activity of HRB and 11 in the presence of EPI significantly increased on the tested bacteria strains (up to 32-fold). The activity of cloxacillin (CLO), doxycycline (DOX), and tetracycline (TET), was considerably improved (up to 64-fold) towards the multidrug-resistant Enterobacter aerogenes EA-CM64 strain. The crude extract (HRB) and 11 induced the leakage of bacterial intracellular components and inhibited the proton-ATPase pumps. CONCLUSIONS: The crude extract (HRB) and 8,8-bis(dihydroconiferyl)diferulate from the bark of Hypericum roeperianum are good antibacterial candidates that deserve further investigations to achieve antibacterial drugs to fight infections involving MDR bacteria.

Bark extract of Cassia sieberiana DC. (Caesalpiniaceae) displayed good antibacterial activity against MDR gram-negative phenotypes in the presence of phenylalanine-arginine ß-naphthylamide.

BACKGROUND: Multidrug-resistant (MDR) bacteria remain a major cause of morbidity and mortality globally. The present study was designed to investigate the in vitro antibacterial activities of crude methanol extract and constituents isolated by Column Chromatography (CC) from Cassia sieberiana bark (CSB) against ten MDR Gram-negative bacteria, as well as the mechanisms of action of the most active sample. METHODS: The antibacterial activity of the tested samples (extract, the fractions and their compounds isolated by CC and the structures obtained by exploiting 1H and 13C Nuclear magnetic resonance (NMR) spectra) in the presence and absence of an efflux pumps inhibitor, phenylalanine-arginine ß-naphthylamide (PAßN), was evaluated using the micro-dilution method. The effects of the most active sample were evaluated on the cell growth kinetic and on the bacterial H+-ATPase proton pumps. RESULTS: Phytochemical composition of the crude extract showed a rather selective distribution of secondary metabolites (presence of polyphenols, tannins, steroids, triterpenes, flavonoids, alkaloids, saponins and absence of anthocyanins, anthraquinones). The tested samples displayed different antibacterial activities with minimal inhibitory concentrations (MICs) ranging from 64 to 512 µg/mL. Crude extract (CS) and fraction CSc showed the highest inhibitory spectra, both inhibiting all of the studied bacteria except Enterobacter aerogenes EA27 strain. Fraction CSc exerted bactericidal effects on most bacteria meanwhile, crude extract (CS) and sub-fraction CSc2 exerted bacteriostatic effects. Compounds 1 (spectaline) and 2 (iso-6-cassine) inhibited the growth of 70% (Escherichia coli ATCC8739 and AG102, Klebsiella pneumoniae ATCC11296, Enterobacter aerogenes ATCC13048 and EA27, Providencia stuartii ATCC29916, Pseudomonas aeruginosa PA01) and 60% (Escherichia coli ATCC8739, Klebsiella pneumoniae ATCC11296 and KP55, Providencia stuartii ATCC29916, Pseudomonas aeruginosa PA01 and PA124) of bacteria respectively with MICs ranging from 128 to 512 µg/mL. In the presence of PAßN, the activities of crude extract CS, fraction CAc and sub-fraction CSc2 strongly increased on most bacteria strains as their MICs significantly decreased. Sub-fraction CSc2 inhibited the H+-ATPase proton pumps and altered growth kinetic of Escherichia coli ATCC8739. CONCLUSION: The overall results justify the traditional use of C. sieberiana for the treatment of bacterial infections.

Contemporaneous data on the prevalence of Human Respiratory Syncytial Virus infection in people with acute respiratory tract infections in Africa (2000-2017).

Availability of accurate data on the burden of the Human Respiratory Syncytial Virus (HRSV) can help to implement better strategies to curb this burden in Africa continent among people with acute respiratory tract infections (ARTI). We summarize here available contemporaneous data published from January 1, 2000 to August 31, 2017 on the prevalence of HSRV infection among people with ARTI in the continent.

Prevalence of respiratory bacterial infections in people with lower respiratory tract infections in Africa: the BARIAFRICA systematic review and meta-analysis protocol.

INTRODUCTION: The burden of lower respiratory tract infections (LRTIs) is a substantial public health concern. However, the epidemiology of LRTI and its bacterial aetiologies are poorly characterised, particularly in the African continent. Providing accurate data can help design cost-effective interventions to curb the burden of respiratory infections in Africa. Therefore, the aim of this systematic review and meta-analysis will be to determine the prevalence of respiratory Bacterial Aetiologies in people with low Respiratory tract Infections in Africa (BARIAFRICA) and associated factors. METHODS AND ANALYSIS: We will search PubMed, EMBASE, Web of Science, African Journals Online, Cumulative Index to Nursing and Allied Health Literature, and Global Index Medicus to identify studies that reported the prevalence (of enough data to compute this estimate) of respiratory bacterial infections in people with LRTIs in Africa from 1 January 2000 to 31 March 2018, without any linguistic restrictions. Study selection, data extraction and risk of bias assessment will be conducted independently by two investigators. Heterogeneity will be evaluated using the χ² test on Cochran's Q statistic and quantified with H and I² statistics. Prevalence will be pooled using a random-effect meta-analysis model. Subgroup and meta-regression analyses will be used to identify sources of heterogeneity of prevalence estimates. This study will be reported according to the guidelines of the Preferred Reporting Items for Systematic Reviews and Meta-Analyses. ETHICS AND DISSEMINATION: Since this study will be based on published data, it does not require ethical approval. This systematic review and meta-analysis is intended to serve as a basis for determining the burden of LRTIs, for identifying data gaps and for guiding future investigations in Africa. The final report will be published in peer-reviewed journals, presented in conferences and submitted to relevant health policy makers. PROSPERO REGISTRATION NUMBER: CRD42018092359.

Prevalence of human respiratory syncytial virus infection in people with acute respiratory tract infections in Africa: A systematic review and meta-analysis.

AIM: The epidemiology of human respiratory syncytial virus (HRSV) infection has not yet been systematically investigated in Africa. This systematic review and meta-analysis are to estimate the prevalence of HRSV infections in people with acute respiratory tract infections (ARTI) in Africa. METHOD: We searched PubMed, EMBASE, Africa Journal Online, and Global Index Medicus to identify observational studies published from January 1, 2000, to August 1, 2017. We used a random-effects model to estimate the prevalence across studies. Heterogeneity (I2 ) was assessed via the chi-square test on Cochran's Q statistic. Review registration: PROSPERO CRD42017076352. RESULTS: A total of 67 studies (154 000 participants) were included. Sixty (90%), seven (10%), and no studies had low, moderate, and high risk of bias, respectively. The prevalence of HRSV infection varied widely (range 0.4%-60.4%). The pooled prevalence was 14.6% (95% CI 13.0-16.4, I2  = 98.8%). The prevalence was higher in children (18.5%; 95% CI 15.8-21.5) compared to adults (4.0%; 95% CI 2.2-6.1) and in people with severe respiratory tract infections (17.9%; 95% CI 15.8-20.1) compared to those with benign forms (9.4%; 95% CI 7.4-11.5); P-values <0.0001. The HRSV prevalence was not associated with sex, subregion in Africa, setting, altitude, latitude, longitude, and seasonality. CONCLUSION: This study suggests a high prevalence of HRSV in people with ARTI in Africa, particularly among children and people with severe clinical form. All innovative strategies to curb the burden should first focus on children which present the highest HRSV-related burden.

Toxicity evaluation of some traditional African spices on breast cancer cells and isolated rat hepatic mitochondria.

BACKGROUND: Fagara leprieuri (FL), Fagara xanthoxyloïdes (FX), Mondia whitei (MW) and Xylopia aethiopica (XA) are used in many African countries as food spices or in traditional medicine to treat several maladies. In this work, we (a) investigate whether the crude spice extracts present selective cytotoxicity for breast cancer cell lines and (b) investigate whether the same extracts affect the bioenergetics and calcium susceptibility of isolated liver mitochondrial fractions. RESULTS: All extracts were cytotoxic to the cell lines studied, with the exception of MW, which was less toxic for a normal cell line. Interestingly, some of the extracts did not depolarize mitochondria in intact breast cancer MCF-7 cells, although this effect was observed in a normal breast cancer cell line (MCF-12A). All extracts increased hepatic mitochondrial state 2/4 respiration and decreased the respiratory control ratio and the transmembrane electric potential. Also, the extracts induced the mitochondrial permeability transition (MPT). CONCLUSIONS: Mitochondrial toxicity may be part of the mechanism by which the spices tested cause inhibition of proliferation and death in the cell lines tested. This study also warrants caution in the excessive use of these spices for human consumption.

Characterization of the antiproliferative activity of Xylopia aethiopica.

BACKGROUND: Xylopia aethiopica, a plant found throughout West Africa, has both nutritional and medicinal uses. The present study aims to characterize the effects of extracts of this plant on cancer cells. RESULTS: We report that X. aethiopica extract prepared with 70% ethanol has antiproliferative activity against a panel of cancer cell lines. The IC50 was estimated at 12 µg/ml against HCT116 colon cancer cells, 7.5 µg/ml and > 25 µg/ml against U937 and KG1a leukemia cells, respectively. Upon fractionation of the extract by HPLC, the active fraction induced DNA damage, cell cycle arrest in G1 phase and apoptotic cell death. By using NMR and mass spectrometry, we determined the structure of the active natural product in the HPLC fraction as ent-15-oxokaur-16-en-19-oic acid. CONCLUSION: The main cytotoxic and DNA-damaging compound in ethanolic extracts of Xylopia aethiopica is ent-15-oxokaur-16-en-19-oic acid.

Antimicrobial and toxicological activities of five medicinal plant species from Cameroon traditional medicine.

BACKGROUND: Infectious diseases caused by multiresistant microbial strains are on the increase. Fighting these diseases with natural products may be more efficacious. The aim of this study was to investigate the in vitro antimicrobial activity of methanolic, ethylacetate (EtOAc) and hexanic fractions of five Cameroonian medicinal plants (Piptadeniastum africana, Cissus aralioides, Hileria latifolia, Phyllanthus muellerianus and Gladiolus gregasius) against 10 pathogenic microorganisms of the urogenital and gastrointestinal tracts. METHODS: The fractions were screened for their chemical composition and in vivo acute toxicity was carried out on the most active extracts in order to assess their inhibitory selectivity. The agar well-diffusion and the micro dilution methods were used for the determination of the inhibition diameters (ID) and Minimum inhibitory concentrations (MIC) respectively on 8 bacterial species including two Gram positive species (Staphylococcus aureus, Enterococcus faecalis), and six Gram negative (Escherichia coli, Klebsiella pneumoniae, Pseudomonas aeruginosa, Proteus mirabilis, Shigella flexneri, Salmonella typhi) and two fungal isolates (Candida albicans, Candida krusei). The chemical composition was done according to Harbone (1976), the acute toxicity evaluation according to WHO protocol and the hepatic as well as serum parameters measured to assess liver and kidney functions. RESULTS: The chemical components of each plant's extract varied according to the solvent used, and they were found to contain alkaloids, flavonoids, polyphenols, triterpens, sterols, tannins, coumarins, glycosides, cardiac glycosides and reducing sugars. The methanolic and ethylacetate extracts of Phyllanthus muellerianus and Piptadeniastum africana presented the highest antimicrobial activities against all tested microorganisms with ID varying from 8 to 26 mm and MIC from 2.5 to 0.31 mg/ml. The in vivo acute toxicity study carried out on the methanolic extracts of Phyllanthus muellerianus and Piptadeniastrum africana indicated that these two plants were not toxic. At the dose of 4 g/kg body weight, kidney and liver function tests indicated that these two medicinal plants induced no adverse effect on these organs. CONCLUSION: These results showed that, all these plant's extracts can be used as antimicrobial phytomedicines which can be therapeutically used against infections caused by multiresistant agents. Phyllanthus muellerianus, Piptadeniastum africana, antimicrobial, acute toxicity, kidney and liver function tests, Cameroon Traditional Medicine.

Mycobacterium tuberculosis complex drug resistance pattern and identification of species causing tuberculosis in the West and Centre regions of Cameroon.

BACKGROUND: Data on the levels of resistance of Mycobacterium tuberculosis complex (MTBC) strains to first line anti-tuberculosis drugs in Cameroon, and on the species of MTBC circulating in the country are obsolete. The picture about 10 years after the last studies, and 6 years after the re-organisation of the National Tuberculosis (TB) Control Programme (NTBCP) is not known. METHODS: The study was conducted from February to July 2009 in the West and Centre regions of Cameroon. A total of 756 suspected patients were studied. MTBC species were detected by the standard Ziehl-Neelsen staining method. Bacterial susceptibility to the first line drugs [isoniazid (INH), rifampicin (RIF), ethambutol (EMB) and streptomycin (SM)] were performed on cultures using the indirect proportion method. MTBC species were identified by standard biochemical and culture methods. RESULTS: Of the 756 suspected patients, 154 (20.37%) were positive by smear microscopy. Of these, 20.77% were HIV patients. The growth of Mycobacterium was observed with the sputa from 149 (96.75%) subjects. All the isolates were identified as either M. tuberculosis or M. africanum. Among these, 16 (10.73%) were resistant to at least one drug (13.3% for the West region and 8.1% for the Centre). The initial resistance rates were 7.35% for the Centre region and 11.29% for the West region, while the acquired resistance rates were 16.66% (1/6) for the Centre region and 23.07% (3/13) for the West. Within the two regions, the highest total resistance to one drug was obtained with INH and SM (2.68% each). Multidrug-resistance (MDR) was observed only in the West region at a rate of 6.67%. No resistance was recorded for EMB. CONCLUSIONS: M. tuberculosis and M. africanum remain the MTBC species causing pulmonary TB in the West and Centre regions of Cameroon. Following the re-organisation of the NTBCP, resistance to all first line anti-TB drugs has declined significantly (p < 0.05 for West; and p < 0.01 for Centre) in comparison to previous studies. However, the general rates of anti-TB drug resistance remain high in the country, underscoring the need for greater enforcement of control strategies.