Browsing by Author "Okeng, Alfred"

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    Accuracy of GenoQuick MTB Test in Detection of Mycobacterium tuberculosis in Sputum from TB
    (SAGE Open Medicine, 2022) Kaswabuli, Sylvia; Musisi, Emmanuel; Byanyima, Patrick; Sessolo, Abdul; Sanyu, Ingvar; Zawedde, Josephine; Worodria, William; Okeng, Alfred; Bwanga, Freddie
    The objective of the study was to determine the diagnostic performance of the GenoQuick MTB test on heated sputum against the conventional Lowenstein–Jensen Mycobacterium tuberculosis culture as the reference method for tuberculosis diagnosis. Fast, reliable, and easy-to-use tests for tuberculosis diagnosis are essential to achieving the Sustainable Development Goal of diagnosing and treating 90% of tuberculosis patients by 2030. We evaluated the diagnostic performance of the GenoQuick MTB, a polymerase chain reaction–lateral flow test, in Uganda, a resource-constrained, high tuberculosisand HIV-burden setting. Fresh sputum samples from presumptive tuberculosis patients at Mulago Hospital were tested for M. tuberculosis using smear microscopy, GenoQuick MTB test, and Lowenstein–Jensen culture. For the GenoQuick MTB test, mycobacterial DNA was extracted by heating sputum at 95°C for 30min while DNA amplification and detection were done following the manufacturer’s protocol (Hain Lifescience, Nehren, Germany). Sensitivity, specificity, and kappa agreements were calculated against Lowenstein–Jensen M. tuberculosis culture as a reference test using STATA V12. Of the 86 tested samples, 30.2% had culture-confirmed pulmonary tuberculosis. Overall, sensitivity was higher for GenoQuick MTB (81%, 95% confidence interval: 60%−93%) than for smear microscopy (69%, 95% confidence interval: 48%−86%). Among people living with HIV, sensitivity was identical for GenoQuick MTB and smear tests (75%, 95% confidence interval: 42%−95%). Contrastingly, smear had a higher overall specificity (98%, 95% confidence interval: 91%−100%) than for GenoQuick MTB (92%, 95% confidence interval: 81%−97%). A similar trend of specificity was observed among the people living with HIV for smear microscopy (100%, 95% CI: 87%−100%) and for GenoQuick MTB (96%, 95% confidence interval: 81%−100%). The GenoQuick MTB test could be a potential tuberculosis diagnostic test given its higher sensitivity. Evaluation of this test in larger studies is recommended.
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    Helicobacter pylori from Peptic Ulcer Patients in Uganda Is Highly Resistant to Clarithromycin and Fluoroquinolones: Results of the GenoType HelicoDR Test Directly Applied on Stool
    (BioMed research international, 2017) Calmax Angol, Denish; Ocama, Ponsiano; Ayazika Kirabo, Tess; Okeng, Alfred; Najjingo, Irene; Bwanga, Freddie
    Around 70–90% of peptic ulcer disease (PUD) is due to Helicobacter pylori and requires treatment with antimicrobials to which these bacteria are susceptible. Common H. pylori diagnostic tests do not provide drug susceptibility data. Using the GenoType HelicoDR PCR test designed for gastric biopsies for simultaneous detection of H. pylori and its resistance to clarithromycin (CLA)/fluoroquinolones (FLQ), we present evidence for stool as an optional test specimen and also provide data on prevalence of H. pylori resistance to CLA and FLQ in Uganda. Methods. Stool from 142 symptomatic PUD patients at three hospitals in Kampala was screened for H. pylori using a rapid antigen test.The GenoType HelicoDR test was run on all H. pylori antigen positives to determine PCR positivity and resistance to CLA/FLQ. Results. Thirty-one samples (22%) were H. pylori antigen positive, and 21 (68%) of these were H. pylori PCR positive. Six of the 21 (29%) were resistant to CLA and eight to FLQ (42%), while two gave invalid FLQ resistance results. Conclusion. Stool is a possible specimen for the GenoType HelicoDR test for rapid detection of H. pylori and drug resistance. In Uganda, Helicobacter pylori is highly resistant to CLA and FLQ.
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    Identification of Staphylococcus aureus: DNase and Mannitol salt agar improve the efficiency of the tube coagulase test
    (Annals of clinical microbiology and antimicrobials, 2010) Kateete, David P.; Kimani, Cyrus N.; Katabazi, Fred A.; Okeng, Alfred; Okee, Moses S.; Nanteza, Ann; Joloba, Moses L.; Najjuka, Florence C.
    The ideal identification of Staphylococcus aureus clinical isolates requires a battery of tests and this is costly in resource limited settings. In many developing countries, the tube coagulase test is usually confirmatory for S. aureus and is routinely done using either human or sheep plasma. This study evaluated Mannitol salt agar and the deoxyribonuclease (DNase) test for improving the efficiency of the tube coagulase test in resource limited settings. The efficiency of human and sheep plasma with tube coagulase tests was also evaluated.
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    Rhomboids of Mycobacteria: Characterization Using an aarA Mutant of Providencia stuartii and Gene Deletion in Mycobacterium smegmatis
    (Plos One, 2012) Kateete, David Patrick; Katabazi, Fred Ashaba; Okeng, Alfred; Okee, Moses; Musinguzi, Conrad; Asiimwe, Benon Byamugisha; Kyobe, Samuel; Asiimwe, Jeniffer; Boom, W. Henry; Joloba, Moses Lutaakome
    Rhomboids are ubiquitous proteins with unknown roles in mycobacteria. However, bioinformatics suggested putative roles in DNA replication pathways and metabolite transport. Here, mycobacterial rhomboid-encoding genes were characterized; first, using the Providencia stuartii null-rhomboid mutant and then deleted from Mycobacterium smegmatis for additional insight in mycobacteria.Using in silico analysis we identified in M. tuberculosis genome the genes encoding two putative rhomboid proteins; Rv0110 (referred to as “rhomboid protease 1”) and Rv1337 (“rhomboid protease 2”). Genes encoding orthologs of these proteins are widely represented in all mycobacterial species. When transformed into P. stuartii null-rhomboid mutant (ΔaarA), genes encoding mycobacterial orthologs of “rhomboid protease 2” fully restored AarA activity (AarA is the rhomboid protein of P. stuartii). However, most genes encoding mycobacterial “rhomboid protease 1” orthologs did not. Furthermore, upon gene deletion in M. smegmatis, the ΔMSMEG_4904 single mutant (which lost the gene encoding MSMEG_4904, orthologous to Rv1337, “rhomboid protease 2”) formed the least biofilms and was also more susceptible to ciprofloxacin and novobiocin, antimicrobials that inhibit DNA gyrase. However, the ΔMSMEG_5036 single mutant (which lost the gene encoding MSMEG_5036, orthologous to Rv0110, “rhomboid protease 1”) was not as susceptible. Surprisingly, the double rhomboid mutant ΔMSMEG_4904–ΔMSMEG_5036 (which lost genes encoding both homologs) was also not as susceptible suggesting compensatory effects following deletion of both rhomboid-encoding genes. Indeed, transforming the double mutant with a plasmid encoding MSMEG_5036 produced phenotypes of the ΔMSMEG_4904 single mutant (i.e. susceptibility to ciprofloxacin and novobiocin).Mycobacterial rhomboid-encoding genes exhibit differences in complementing aarA whereby it's only genes encoding “rhomboid protease 2” orthologs that fully restore AarA activity. Additionally, gene deletion data suggests inhibition of DNA gyrase by MSMEG_4904; however, the ameliorated effect in the double mutant suggests occurrence of compensatory mechanisms following deletion of genes encoding both rhomboids.