Browsing by Author "Hsiao, Nei-Yuan"

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    Open Access
    Analysis of cytomegalovirus UL97 drug resistance mutations in patients receiving Ganciclovir
    (2018) Nkosi, Nokwazi Pearl; Hsiao, Nei-Yuan; Korsman, Stephen; Smuts, Heidi
    Introduction: Cytomegalovirus (CMV) drug resistance mutations, because of the widespread use of ganciclovir, have been widely reported in international literature, particularly in the post-transplant setting. However, a genotypic assay to detect CMV drug resistance is not available in South Africa and the prevalence of these mutations is therefore unknown. We aimed to document the prevalence and types of CMV UL97 mutations following exposure to ganciclovir in adult and paediatric oncology patients, transplant recipients and HIV-infected patients in the local tertiary level hospitals: Red Cross War Memorial Children's Hospital, Groote Schuur Hospital and Tygerberg Hospital. Methods: The study had two components, the first component being a retrospective cross-sectional study using stored extracted DNA from patients with serially elevated CMV viral load levels. Thirty-three samples were tested for this component. The second component was a prospective case series on patients who were referred by clinicians for genotypic testing in whom CMV drug resistance was suspected. Eight samples were tested for this component. The CMV UL97 gene was amplified by conventional nested polymerase chain reaction (PCR) and Sanger sequencing performed. Results: CMV UL97 mutations were identified in five of thirty-three (15%) retrospectively screened samples while the prospective testing of eight patient samples identified drug resistance mutations in three patients (38%). Overall 8/41 (20%) patients had CMV UL97 mutations. A trend of higher risk for development of drug resistance mutations among haematological oncology patients 7/23 (30%) compared to solid organ transplant recipients 1/10 (10%) was observed, however, this difference was not statistically significant (P=0.306). Conclusion: This study, the first of its nature in South Africa, identified the presence of CMV UL97 mutations conferring resistance to ganciclovir in the haematological oncology, primary immunodeficiency and solid organ transplant patients in the Western Cape. The assay successfully detected CMV UL97 drug resistance mutations in whole blood and cerebrospinal fluid clinical samples. Ongoing viral replication in the background of intensive immunosuppression and prolonged antiviral therapy selects for the emergence of CMV UL97 drug resistance mutations.
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    Analysis of HIV early infant diagnosis and linkage to care in the Western Cape: a laboratory perspective
    (2012) Hsiao, Nei-Yuan
    Prevention of mother-to-child transmission (PMTCT) of HIV is the cornerstones of HIV prevention programs. The principle of using antiretrovirals (ARV) to reduce the risk of transmission from mother to child is well established as a range of PMTCT regimens with varying efficacies have been widely studied and reviewed1. In South Africa and other Sub-Saharan countries, single dose Nevirapine, amongst other cost- effective regimens, have been adopted as part of the national HIV prevention program2 since 2003.
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    Cytomegalovirus viraemia in immunocompromised children in Cape Town
    (2009) Hsiao, Nei-Yuan; Hardie, Diana
    Includes bibliographical references (leaves 54-62).
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    Human Parainfluenza Virus (HPIV) Detection in Hospitalized Children with Acute Respiratory Tract Infection in the Western Cape, South Africa during 2014–2022 Reveals a Shift in Dominance of HPIV 3 and 4 Infections
    (Multidisciplinary Digital Publishing Institute, 2023-08-02) Parsons, Jane; Korsman, Stephen; Smuts, Heidi; Hsiao, Nei-Yuan; Valley-Omar, Ziyaad; Gelderbloem, Tathym; Hardie, Diana
    The epidemiology of human parainfluenza viruses (HPIV), particularly its role as a cause of acute respiratory infection (ARI) in infants, has not been formally studied in South Africa. We evaluated HPIV prevalence in diagnostic samples from hospitalized children from public sector hospitals in the Western Cape between 2014 and 2022. HPIV infection was detected in 2–10% of patients, with the majority of infections detected in children less than 1 year of age. Prior to 2020, HPIV 4 (40%) and HPIV 3 (34%) were the most prevalent types, with seasonal peaks in late winter/spring for HPIV 3 and autumn/winter for HPIV 4. HPIV 4A and 4B co-circulated during the seasonal activity between 2014 and 2017. Pandemic restrictions in 2020 had a profound effect on HPIV circulation and the rebound was dominated by waves of HPIV 3, accounting for 66% of detections and a sustained decline in the circulation of HPIV 1, 2 and 4. An immunity gap could account for the surge in HPIV 3 infections, but the decline in prior HPIV 4 dominance is unexplained and requires further study.
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    Improved detection of Pneumocystis jirovecii in upper and lower respiratory tract specimens from children with suspected pneumocystis pneumonia using real-time PCR: a prospective study
    (BioMed Central Ltd, 2011) Samuel, Catherine M; Whitelaw, Andrew; Corcoran, Craig; Morrow, Brenda; Hsiao, Nei-Yuan; Zampoli, Marco; Zar, Heather
    BACKGROUND: Pneumocystis pneumonia (PCP) is a major cause of hospitalization and mortality in HIV-infected African children. Microbiologic diagnosis relies predominantly on silver or immunofluorescent staining of a lower respiratory tract (LRT) specimens which are difficult to obtain in children. Diagnosis on upper respiratory tract (URT) specimens using PCR has been reported useful in adults, but data in children are limited. The main objectives of the study was (1) to compare the diagnostic yield of PCR with immunofluorescence (IF) and (2) to investigate the usefulness of upper compared to lower respiratory tract samples for diagnosing PCP in children. METHODS: Children hospitalised at an academic hospital with suspected PCP were prospectively enrolled. An upper respiratory sample (nasopharyngeal aspirate, NPA) and a lower respiratory sample (induced sputum, IS or bronchoalveolar lavage, BAL) were submitted for real-time PCR and direct IF for the detection of Pneumocystis jirovecii. A control group of children with viral lower respiratory tract infections were investigated with PCR for PCP. RESULTS: 202 children (median age 3.3 [inter-quartile range, IQR 2.2 - 4.6] months) were enrolled. The overall detection rate by PCR was higher than by IF [180/349 (52%) vs. 26/349 (7%) respectively; p < 0.0001]. PCR detected more infections compared to IF in lower respiratory tract samples [93/166 (56%) vs. 22/166 (13%); p < 0.0001] and in NPAs [87/183 (48%) vs. 4/183 (2%); p < 0.0001]. Detection rates by PCR on upper (87/183; 48%) compared with lower respiratory tract samples (93/166; 56%) were similar (OR, 0.71; 95% CI, 0.46 - 1.11). Only 2/30 (6.6%) controls were PCR positive. CONCLUSION: Real-time PCR is more sensitive than IF for the detection of P. jirovecii in children with PCP. NPA samples may be used for diagnostic purposes when PCR is utilised. Wider implementation of PCR on NPA samples is warranted for diagnosing PCP in children.