African Journal of Laboratory Medicine最新文献

Background: Serum protein electrophoresis (SPE), urine protein electrophoresis and immunofixation electrophoresis were traditionally utilised for the diagnosis of monoclonal gammopathies. The quantitative serum-free light chain (SFLC) assay is reportedly more sensitive and has been introduced to recent clinical guidelines.

Objective: This study aimed to investigate SFLC test utilisation and describe SPE findings in patients with abnormal SFLC ratios.

Methods: A retrospective audit of SFLC analyses was conducted in Cape Town, South Africa, from May 2018 to April 2020. Agreement between abnormal SFLC ratios and SPE results was determined in a sub-group of patients screened for monoclonal gammopathies. Serum-free light chains were analysed using Freelite^® Kappa and Lambda assays.

Results: Of the 1425 patients included in the audit, 741 (52%) had abnormal SFLC ratios; 636 (45%) had increased and 105 (7%) had decreased SFLC ratios. In a sub-group analysis of 117 new patients with an abnormal SFLC ratio, 57 had a monoclonal protein (M-protein) on SPE (49%), and 60 (51%) did not. Four out of 60 patients without M-protein had a plasma cell dyscrasia, while renal impairment or inflammatory response accounted for the rest. Of the 57 patients with a M-protein and abnormal SFLC ratio, 41 (72%) had a plasma cell dyscrasia, seven (12%) had lymphomas and nine patients (16%) were unclassifiable.

Conclusion: Serum-free light chains should be requested when there is a high index of clinical suspicion. Neither SFLC nor SPE should be performed in isolation when screening patients for monoclonal gammopathy, to ensure that no patient is missed.

What this study adds: The study adds to the evidence on SFLC test utilisation. Serum protein electrophoresis alone may miss cases of light chain myeloma, while SFLC performed in isolation may produce false positive results in the setting of inflammatory disorders or renal impairment, leading to unnecessary further investigation.

Background: Patients with faecal carriage of extended-spectrum beta-lactamases (ESBL)-producing Enterobacterales serve as reservoirs and sources of dissemination and infection.

Objective: This report examined immunocompetent patients for faecal carriage of ESBL-producing Enterobacterales in a district care hospital setting in Ghana.

Methods: Between March 2019 and May 2020, cross-sectional sampling was performed to enrol patients and conduct questionnaire-structured interviews for factors that predispose patients to ESBL faecal carriage. Faecal samples from study patients were quantified for ESBL-producing Enterobacterales. The ESBL genes were characterised by polymerase chain reaction and sequencing.

Results: The overall proportion of ESBL faecal carriage was 35.5% (n = 38/107). The bla_CTX-M gene, mostly CTX-M-15, was detected in 89.5% (n = 34/38) of the ESBL-producing isolates. The other ESBL types included bla_SHV (n = 3) and bla_OXA (n = 1). The CTX-M-15-positive isolates, when present in a faecal sample compared to the non-ESBL-CTX-M-15 isolates, constituted the predominant faecal Enterobacterales, with significantly higher colony counts than all other enterobacteria in that sample. In multivariate regression, independent risk factors for faecal carriage of ESBL-producing Enterobacterales were hospitalisation in the past year, infections since admission, use of antibiotics in the past 6 weeks, and admission from another hospital.

Conclusion: The study found that CTX-M-15-producing isolates were the predominant faecal Enterobacterales, and that further investigations are needed to determine the reasons behind this dominance.

What this study adds: The CTX-M-15-producing isolates dominance in this study shows the misuse and abuse of antibiotics in an African medical facility and indicates the potential role of immunity in controlling ESBL spread, which is to be investigated further.

Background: Within the African meningitis belt, yearly outbreaks of cerebrospinal meningitis (CSM), with incidence rates of 10-100 cases per 100 000 population, are typically punctuated by explosive epidemics occurring every 8-12 years, with incidence rates that can exceed 1000 cases per 100 000 population. From 1928 to 2018, Nigeria recorded the highest number (21%) of cases in the region. The reactive vaccination strategy, a protocol with major drawbacks, has been the vaccination method utilised in Nigeria.

Aim: This review highlights the need for governments within the African meningitis belt to start preparations against the next explosive CSM epidemic expected to occur between 2024 and 2028 using the preventive vaccination strategy.

Methods: We performed a literature search on the Google Scholar search engine using relevant search strings and included studies and reports between 1905 and 2022 that met set criteria.

Results: Neisseria meningitidis serogroups A, B, C, W135, X, and Y; Haemophilus influenzae serotypes a, b, c, e, and f; and Streptococcus pneumoniae serotypes 1, 4, 5, 6, 9, 19, 19F, and 20 were implicated as aetiologies. However, the reactive vaccination strategy was only used against N. meningitidis A or C, H. influenzae b, and pneumococcal conjugate vaccine. Between 2011 and 2017, a polysaccharide vaccine (ACW or ACYW) active against serogroups A, C, W and Y was used within the African meningitis belt for the first time. Varying genotypes of N. meningitidis, H. influenzae and S. pneumoniae were identified.

Conclusion: Our results revealed a very high success rate for the preventive vaccination strategy.

What this study adds: In order to ensure reductions in the morbidity and mortality associated with invasive CSM, the Federal Ministry of Health, Nigeria, should leverage existing knowledge of the circulating serogroups, serotypes, and genotypes of the primary bacterial aetiologies and commence the implementation of the preventive vaccination strategy.

Background: All medical laboratories must participate in proficiency testing (PT) programmes to ensure high-quality results. Proficiency testing samples mimic clinical samples; however, PT programmes for detection of bacteria in blood products are not routinely performed due to unavailability of matrix-equivalent samples.

Objective: The aim of this study was to develop and test a matrix-equivalent PT programme using blood products as the basis matrix.

Methods: A prospective cross-sectional study was conducted from April 2021 until June 2021, using 52 blood products comprising 36 pooled platelet and 16 red blood cell products at the South African National Blood Service PT laboratory in Gauteng. Products were manipulated into matrix-equivalent PT samples by spiking 42 products with known bacterial strains at specific concentrations and treating the remaining 10 products with preserving fluid containing antibiotics. The level of agreement between the researcher results and participating laboratories' results was assessed.

Results: Of the prepared matrices, 568 out of 572 (99%) were stable for 30 days. Bacteria could correctly be identified in spiked samples for up to 23 days. Samples treated with preserving fluid remained negative until day 30. For spiked samples, an average of 98% agreement (153/156) was achieved between the three participating laboratories when compared with the researcher's results; 100% agreement was achieved for unspiked samples. The kappa scores obtained from all tested variables presented with scores between 0.856 and 1.000, and the p-value was < 0.001 throughout.

Conclusion: The developed PT matrix was therefore stable and suitable to be implemented in transfusion microbiology.

What this study adds: This study demonstrated that a stable microbiology PT programme using platelets and red blood cells can be developed for use on bacterial detection analysers and could help to close the gap presented by unavailability of a blood PT matrix for transfusion microbiology.

Background: Integrated testing, treatment and care are key strategies for addressing the dual burdens of tuberculosis and HIV. The GeneXpert instrument allows simultaneous HIV and tuberculosis testing, but its utilisation for integrated testing remains suboptimal.

Objective: The study determined the extent to which tuberculosis testing and HIV early infant detection (EID) were integrated on the GeneXpert platform, or the potential for integration at selected health facilities.

Methods: A mixed methods evaluation was conducted using retrospective secondary data analysis of laboratory records from 2017 to 2019, and semi-structured interviews. Data were collected between January 2020 and March 2020 in Lesotho.

Results: Forty-four health staff were interviewed across 13 health facilities: one regional, nine district, and three clinic level. Six were government facilities, six were mission hospitals, and one was a non-profit clinic. All facilities selected had at least one GeneXpert instrument used for tuberculosis or HIV testing; none included simultaneous testing for tuberculosis and HIV. In 2017, the average utilisation rate for the GeneXpert instrument for tuberculosis and EID testing was 63% and 24%, while in 2019, the average utilisation rate was 61% for tuberculosis testing and 27% for EID.

Conclusion: Except for three sites where the testing rates were high, utilisation rates were sufficiently low that all the HIV EID and tuberculosis tests undertaken in 2017 and 2019 could have been performed using only the instruments currently dedicated to tuberculosis testing. There is a missed opportunity for the integration of testing for tuberculosis and HIV on the GeneXpert instrument.

What this study adds: This study adds to the body of evidence on the need for integration of testing and highlights some practical and technical considerations for successful implementation of integrated tuberculosis and HIV testing.

Background: Coronavirus disease 2019 (COVID-19) is a worldwide public health concern for healthcare workers. About 80% of cases appear to be asymptomatic, and about 3% may experience hospitalisation and later die. Less than 20% of studies have looked at the positivity rate of asymptomatic individuals.

Objective: This study investigated the COVID-19 positivity rates among asymptomatic individuals during the second COVID-19 wave at one of Zambia's largest testing centre.

Methods: This was a retrospective cross-sectional study conducted on routine surveillance and laboratory data at the Tropical Diseases Research Centre COVID-19 laboratory in Ndola, Zambia, from 01 December 2020 to 31 March 2021. The study population was made up of persons that had tested for severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection as a requirement for travel. Microsoft Excel was used to come up with an epidemiological curve of daily COVID-19 positive cases; proportions for gender were described using frequencies and percentages.

Results: A total of 11 144 asymptomatic individuals tested for SARS-CoV-2 were sampled for the study and 1781 (16.0%) returned positive results. The median age among those tested was 36 years (interquartile range: 29-46). Testing for COVID-19 peaked in the month of January 2021 (37.4%) and declined in March 2021 (21.0%). The epidemiological curve showed a combination of continuous and propagated point-source transmission.

Conclusion: The positivity rate of 16.0% among asymptomatic individuals was high and could imply continued community transmission, especially during January 2021 and February 2021. We recommend heightened testing for SARS-CoV-2 among asymptomatic individuals.

What this study adds: This study adds critical knowledge to the transmission of COVID-19 among asymptomatic travellers who are usually a key population in driving community infection. This knowledge is critical in instituting evidence-based interventions in the screening and management of travellers, and its control.