African Journal of Laboratory Medicine最新文献

Background: Monoclonal gammopathies, including multiple myeloma, present significant challenges in sub-Saharan Africa. Diagnosis is often missed because of limited screening tools. The gamma gap and albumin-globulin ratio (AGR) have been proposed as simple, cost-effective screening methods; however, their utility in settings with prevalent infectious and inflammatory diseases is unclear.

Objective: This study evaluated the diagnostic accuracy of gamma gap and AGR in identifying patients who require further investigation for monoclonal gammopathies in South Africa.

Methods: A retrospective analysis of 7946 patients who underwent investigations for monoclonal gammopathies at Groote Schuur Hospital, South Africa, between September 2015 and September 2022 was conducted. Patients were classified based on monoclonal protein detection, and the gamma gap, AGR, and multivariable models were evaluated for diagnostic performance.

Results: Among the patients (median age: 61 years, 58% female [4632/7946] and 42% [3314/7946] male patients), 1231 had monoclonal proteins. A gamma gap cutoff of 46 g/L identified 35% of monoclonal cases (sensitivity), with 91% specificity and an area under the curve (AUC) of 0.60. The AGR showed a slightly better AUC of 0.63, with 44% sensitivity and 80% specificity at a 0.85 cutoff. Multivariable models incorporating age, sex, and hypogammaglobulinaemia improved performance, with the gamma gap model achieving an AUC of 0.73, improving the sensitivity to 58%, with a specificity of 78%.

Conclusion: The gamma gap and AGR showed low sensitivity and moderate specificity in screening for monoclonal gammopathies, highlighting the need for integrated diagnostic approaches combining clinical, demographic, and laboratory data to improve early detection in resource-limited settings.

What this study adds: Although cost-effective and widely available, gamma gap and AGR have limited accuracy for screening monoclonal gammopathies when used alone in settings with prevalent infectious and inflammatory diseases. Although the tests are good at ruling out monoclonality, they risk missing many true cases, delaying diagnosis and treatment.

Introduction: Hairy cell leukaemia (HCL) is a rare B-cell lymphoproliferative disorder characterised by medium-sized villous lymphocytes ('hairy cells') and monocytopenia in the peripheral blood. Automated full blood count (FBC) haematology analysers may spuriously count 'hairy cells' as monocytes, resulting in pseudomonocytosis.

Case presentation: A 72-year-old woman presented with symptomatic anaemia and massive splenomegaly to a regional hospital in North West province, South Africa, in June 2023. An FBC and differential count, performed on a Sysmex XN-series haematology analyser, revealed a monocytosis of 42.82 × 10⁹/L. However, a manual differential count, peripheral blood microscopy, and multiparameter flow cytometry confirmed a monocytopenia with numerous 'hairy cells'.

Management and outcome: The patient was referred to a tertiary hospital where bone marrow morphology and a BRAFV600E mutation confirmed a diagnosis of HCL. Unfortunately, she demised shortly after admission.

Conclusion: Here, we report a case of HCL where a Sysmex XN-series artifactually counted 'hairy cells' as monocytes, masking the characteristic monocytopenia. With the recent introduction of Sysmex XN-series FBC haematology analysers (Sysmex Corporation, Kobe, Japan) in National Health Laboratory Service laboratories across South Africa, we urge operators to be cognisant of the inherent limitations of FBC analysers in generating blood counts.

What this study adds: Even modern automated laboratory analysers with advanced technologies have inherent limitations. This case highlights the importance of a manual differential count and peripheral blood smear review in the era of automation.

Background: Hyperuricaemia is a risk factor for gout and independently predicts hypertension, diabetes, and chronic kidney disease development. While elevated uric acid levels occur in HIV patients, and weight gain is linked to dolutegravir-based therapy, data on the obesity-hyperuricaemia relationship in this population remain limited.

Objective: The objective of our study was to evaluate the association between obesity and hyperuricaemia among HIV-positive patients on antiretroviral therapy in South-Western Uganda.

Methods: Between April 2024 and June 2024, this study conducted a secondary analysis of data on uric acid level and factors associated with obesity from a 2023 cross-sectional study of HIV-positive participants. We used logistic regression to assess the factors associated with hyperuricaemia, and receiver operating characteristic curve analysis to assess the predictive performance of body mass index for hyperuricaemia.

Results: Among 328 participants, hyperuricaemia prevalence was 23.48% (95% confidence interval [CI]: 19.19-28.39%) higher in male participants (31.6%) than female participants (20.0%, p = 0.023). Overweight (adjusted odds ratio [aOR]: 2.01; 95% CI: 1.01-4.00; p = 0.046), obesity (aOR: 2.50; 95% CI: 1.09-5.73, p = 0.030), and male gender (aOR: 2.31; 95% CI: 1.07-5.01, p = 0.033) were significantly associated with hyperuricaemia.

Conclusion: Our findings indicate a relationship between hyperuricaemia and obesity in HIV patients on antiretroviral therapy in Uganda. Nationwide studies using primary data are needed to better understand this relationship's epidemiological spread.

What this study adds: This study is the first to link obesity with hyperuricaemia among HIV-positive Ugandans on antiretroviral therapy, highlighting obesity as a key metabolic complication of HIV treatment.

Background: Urinary tract infections (UTIs) are prevalent bacterial infections, necessitating rapid and accurate diagnosis for timely treatment. Conventional culture techniques, such as cystine lactose electrolyte deficient (CLED) agar, can delay treatment and contribute to inappropriate antibiotic use. Not much is known about alternatives such as chromogenic UTI agar.

Objective: The study aimed to assess the performance of chromogenic UTI agar compared to conventional methods for identifying uropathogens, especially in polymicrobial infections, and to determine its sensitivity, specificity, time efficiency, and cost-effectiveness for UTI diagnosis.

Methods: An observational cross-sectional study was conducted from March 2024 to June 2024 in the Microbiology Department of M.P. Shah Government Medical College in Jamnagar, Gujarat, India. Urine samples from patients with suspected UTIs (n = 250) were processed using both chromogenic UTI agar and CLED agar. The performance of chromogenic UTI agar was assessed for pathogen identification, detection of polymicrobial infections, time to results, and cost-effectiveness.

Results: Chromogenic UTI agar detected single bacterial growth in 63/250 (25.2%) samples, and mixed bacterial growth in 24/250 (9.6%) samples, whereas CLED agar showed single bacterial growth in 67/250 (26.8%) samples and mixed bacterial growth in 10/250 (4%). The chromogenic medium provided preliminary results 5.5 h earlier (p < 0.001) and final results 24 h earlier (p < 0.001) than conventional methods. Cost analysis revealed a 33% reduction per-test cost using chromogenic UTI agar (p < 0.001).

Conclusion: Chromogenic UTI agar demonstrated excellent performance in the rapid and accurate diagnosis of UTIs, including improved detection of polymicrobial infections.

What this study adds: When it comes to diagnosing UTIs, chromogenic UTI agar has several benefits over traditional techniques, such as high accuracy, enhanced detection of polymicrobial infections, and cost-effectiveness. The research backs up the inclusion of chromogenic medium in standard UTI diagnosis procedures.

Background: The coronavirus disease 2019 (COVID-19) pandemic strained diagnostic testing capacities globally, particularly in low- and middle-income countries like Nigeria. Reverse-transcription polymerase chain reaction (RT-PCR) remains the gold standard for COVID-19 detection, but limited testing resources caused bottlenecks in Nigeria's response during the pandemic. Sample pooling offers a cost-effective strategy to enhance testing capacity during future outbreaks.

Objective: This study determined the maximum number of COVID-19 samples that can be pooled for RT-PCR testing in Nigeria without compromising the detection sensitivity of a single positive sample.

Methods: A total of 1222 nasopharyngeal samples from symptomatic COVID-19 patients in Nasarawa State, Nigeria, collected between March 2021 and August 2022, were retrieved from the laboratory biorepository and analysed from November 2022 to February 2023. These included five positive samples with cycle threshold (Ct) values ranging from ≤ 20 to 40, and 1217 negative samples. Positive samples were pooled with negative ones at increasing dilution ratios (1:4-1:64), to assess detection sensitivity on the GeneXpert platform.

Results: A positive sample with a Ct value ≤ 25 could be pooled with up to 64 negative samples while maintaining a detectable positive result. However, samples with Ct values of 36-40 could only be pooled with a maximum of eight negative samples. Higher Ct values reduced pooling effectiveness.

Conclusion: Sample pooling is a feasible method for scaling up COVID-19 RT-PCR testing in resource-limited settings like Nigeria. The Ct value is critical in determining optimal pool sizes for accurate detection.

What this study adds: The findings provide critical guidelines for determining the optimal pool sizes based on Ct values, aiding in effective COVID-19 testing strategies. By optimising sample pooling based on viral load, health authorities can improve their response to future COVID-19 outbreaks and similar public health emergencies.

Background: Flow cytometric characterisation of acute leukaemia is a key diagnostic approach for clinical management of patients, but is minimally practised in resource-constrained settings like Ethiopia.

Objective: This study aimed to determine the immunophenotypes of acute leukaemia by flow cytometry at Tikur Anbessa Specialised Hospital, Addis Ababa, Ethiopia.

Methods: A cross-sectional study was conducted on adolescent and adult inpatients consecutively admitted from April 2019 to June 2021. Peripheral blood samples were stained for surface and cytoplasmic markers, and analysed by four-colour flow cytometry.

Results: Of 140 cases aged 13 years to 76 years, 74 (53%) were men and 66 (47%) were women, 68 (49%) had acute lymphocytic leukaemia (ALL), 65 (46 %) had acute myelogenous leukaemia (AML), and 7 (5.0%) had acute leukaemia non-otherwise specified. Acute lymphocytic leukaemia was more common among adolescent and male cases; AML was more common among adult and female cases. Among ALL subtypes, B-cell acute lymphocytic leukaemia cases (73.5%) were more common than T-cell acute lymphocytic leukaemia (26.5%). A subset of acute leukaemia, CD19+/CD56+ AML was identified in 3 cases (6% of AML). Of the B-cell ALL cases, 21 (42%) were CD34+/CD10+/CD66c+, 10% were CD34+/CD10+/CD66c-, 32% were CD34-/CD10+, and 6% were CD34+/CD10-. An unexpectedly high number of T-cell ALL cases that lacked surface CD3 were observed to have significantly higher levels of aberrantly expressed myeloid markers.

Conclusion: We observed multiple phenotypes identifying subtypes of acute leukaemia cases, extending our previous studies in Ethiopia.

What this study adds: This study extends previous studies by describing phenotypically defined subsets of ALL and AML which, in addition to diagnosis, may have useful prognostic value for clinicians.

Background: Safe management of healthcare waste (HW) safeguards laboratory biosafety and biosecurity. Knowledge and attitudes influence HW practices, presenting a need for evidence of the current status.

Objective: This study assessed the knowledge, attitudes and practice of laboratory workers towards waste management at a regional hospital laboratory in Lesotho.

Methods: The study was conducted from March 2023 to June 2023 using a mixed-methods descriptive case study design. The entire population (n = 30) of technical and non-technical laboratory workers and generated waste were sampled. A structured questionnaire and an observational checklist were used to collect data. Waste generation was assessed by weighing and measuring waste volumes. Data were analysed using descriptive statistics.

Results: All respondents (26/26; 100%) can define HW and (3/3) laboratory assistants (100%) gave correct responses for three questions, namely: risk associated with HW, waste container colour-coding, and disposal requirements. Knowledge on waste management responsibilities ranged between 0% (0/4) for cleaners and 54.5% (6/11) among laboratory technicians. Attitudes were mainly positive, and practices conformed in part to standard operating procedures. Infectious solid waste comprised 77% of solid HW, while 63% of chemical liquid waste emanated from the full blood count area.

Conclusion: Knowledge exists among workers and attitudes are predominantly positive; however, some unsafe practices continue, thus knowledge is not fully translated to safe practices. Regular training and measuring and recording of HW were recommended.

What this study adds: The study contributes understanding of the status of HW knowledge, attitudes and management practices, highlighting the need for compliance monitoring.

Background: There is a paucity of research on the incidence and antimicrobial resistance (AMR) of Enterococcus faecium, Staphylococcus aureus, Klebsiella pneumoniae, Acinetobacter baumannii, Pseudomonas aeruginosa, and Enterobacter spp. (ESKAPE) pathogens in Africa because of the inadequate establishment of AMR surveillance systems.

Objective: This study reports on the incidence and AMR of bloodstream ESKAPE pathogens at a referral hospital in northern South Africa.

Methods: This retrospective descriptive study used routinely collected bloodstream isolates (pathogen identification and antimicrobial susceptibility testing performed using automated systems) from the South African National Health Laboratory Service, from January 2014 to December 2019. Resistant phenotypes analysed included methicillin-resistant S. aureus and carbapenem-resistant A. baumannii.

Results: The ESKAPE pathogen incidence rate was stable from 2014 to 2019 (p = 0.133). The most isolated pathogens were S. aureus (268/746; 35.9%) and A. baumannii (200/746; 26.8%). Staphylococcus aureus increased from 39 isolates in 2014 to 75 in 2019 (p = 0.132). The incidence rate of A. baumannii increased from 11.9% (16/134) in 2015 to 37.8% (68/180) in 2019 (p = 0.009). Most isolates (417/746; 55.9%) were from the neonatal ward. Carbapenem-resistant A. baumannii increased from 68.8% (11/16) in 2014 to 75.0% (51/68) in 2019 (p = 0.009). Methicillin-resistant S. aureus decreased from 56.0% (14/25) in 2016 to 17.3% (13/75) in 2019 (p = 0.260).

Conclusion: Routine data provide essential information on the incidence of ESKAPE pathogens and AMR phenotypes, serving as a basis for an antibiogram, a surveillance tool in antibiotic stewardship programmes.

What this study adds: The study provided local information on the incidence and AMR pattern of ESKAPE pathogens, which is essential when developing empiric treatment protocols for appropriate antibiotic prescribing and infection prevention and control practices.