Browsing by Author "Dube, Felix S."

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    Indoor air pollution and tobacco smoke exposure : impact on nasopharyngeal bacterial carriage in mothers and infants in an African birth cohort study
    (European Respiratory Society, 2019) Vanker, Aneesa; Nduru, Polite M.; Barnett, Whitney; Dube, Felix S.; Sly, Peter D.; Gie, Robert P.; Nicol, Mark P.; Zar, Heather J.
    ENGLISH ABSTRACT: Indoor air pollution (IAP) or environmental tobacco smoke (ETS) exposure may influence nasopharyngeal carriage of bacterial species and development of lower respiratory tract infection (LRTI). The aim of this study was to longitudinally investigate the impact of antenatal or postnatal IAP/ETS exposure on nasopharyngeal bacteria in mothers and infants. A South African cohort study followed mother–infant pairs from birth through the first year. Nasopharyngeal swabs were taken at birth, 6 and 12 months for bacterial culture. Multivariable and multivariate Poisson regression investigated associations between nasopharyngeal bacterial species and IAP/ETS. IAP exposures (particulate matter, carbon monoxide, nitrogen dioxide, volatile organic compounds) were measured at home visits. ETS exposure was measured through maternal and infant urine cotinine. Infants received the 13-valent pneumococcal and Haemophilus influenzae B conjugate vaccines. There were 881 maternal and 2605 infant nasopharyngeal swabs. Antenatal ETS exposure was associated with Streptococcus pneumoniae carriage in mothers (adjusted risk ratio (aRR) 1.73 (95% CI 1.03–2.92)) while postnatal ETS exposure was associated with carriage in infants (aRR 1.14 (95% CI 1.00–1.30)) Postnatal particulate matter exposure was associated with the nasopharyngeal carriage of H. influenzae (aRR 1.68 (95% CI 1.10– 2.57)) or Moraxella catarrhalis (aRR 1.42 (95% CI 1.03–1.97)) in infants. Early-life environmental exposures are associated with an increased prevalence of specific nasopharyngeal bacteria during infancy, which may predispose to LRTI.
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    Molecular epidemiology of Staphylococcus aureus in African children from rural and urban communities with atopic dermatitis
    (BMC (part of Springer Nature), 2021-04-13) Ndhlovu, Gillian O. N.; Abotsi, Regina E.; Shittu, Adebayo O.; Abdulgader, Shima M.; Jamrozy, Dorota; Dupont, Christopher L.; Mankahla, Avumile; Nicol, Mark P.; Hlela, Carol; Levin, Michael E.; Lunjani, Nonhlanhla; Dube, Felix S.
    Background: Staphylococcus aureus has been associated with the exacerbation and severity of atopic dermatitis (AD). Studies have not investigated the colonisation dynamics of S. aureus lineages in African toddlers with AD. We determined the prevalence and population structure of S. aureus in toddlers with and without AD from rural and urban South African settings. Methods: We conducted a study of AD-affected and non-atopic AmaXhosa toddlers from rural Umtata and urban Cape Town, South Africa. S. aureus was screened from skin and nasal specimens using established microbiological methods and clonal lineages were determined by spa typing. Logistic regression analyses were employed to assess risk factors associated with S. aureus colonisation. Results: S. aureus colonisation was higher in cases compared to controls independent of geographic location (54% vs. 13%, p < 0.001 and 70% vs. 35%, p = 0.005 in Umtata [rural] and Cape Town [urban], respectively). Severe AD was associated with higher colonisation compared with moderate AD (86% vs. 52%, p = 0.015) among urban cases. Having AD was associated with colonisation in both rural (odds ratio [OR] 7.54, 95% CI 2.92–19.47) and urban (OR 4.2, 95% CI 1.57–11.2) toddlers. In rural toddlers, living in an electrified house that uses gas (OR 4.08, 95% CI 1.59– 10.44) or utilises kerosene and paraffin (OR 2.88, 95% CI 1.22–6.77) for heating and cooking were associated with increased S. aureus colonisation. However, exposure to farm animals (OR 0.3, 95% CI 0.11–0.83) as well as living in a house that uses wood and coal (OR 0.14, 95% CI 0.04–0.49) or outdoor fire (OR 0.31, 95% CI 0.13–0.73) were protective. Spa types t174 and t1476, and t272 and t1476 were dominant among urban and rural cases, respectively, but no main spa type was observed among controls, independent of geographic location. In urban cases, spa type t002 and t442 isolates were only identified in severe AD, t174 was more frequent in moderate AD, and t1476 in severe AD. Conclusion: The strain genotype of S. aureus differed by AD phenotypes and rural-urban settings. Continued surveillance of colonising S. aureus lineages is key in understanding alterations in skin microbial composition associated with AD pathogenesis and exacerbation.