Dynamics of nasopharyngeal bacterial colonisation in HIV‐exposed young infants in Tanzania

Abstract

To estimate the prevalence of nasopharyngeal bacterial colonisation (NPBC) patterns in young Tanzanian HIV-exposed infants and to analyse the influence of maternal NPBC and of the infant's HIV status on the NPBC pattern. Longitudinal cohort study of neonates born to HIV-infected mothers visiting Kilimanjaro Christian Medical Centre, Tanzania, between 2005 and 2009. Demographic and clinical data and nasopharyngeal bacterial cultures were obtained at the age of 6weeks, 3 and 6months, and at one time point, a paired mother-infant nasopharyngeal swab was taken. Four hundred and twenty-two swabs were taken from 338 eligible infants. At 6weeks of age, colonisation rates were 66% for Staphylococcus aureus, 56% for Streptococcus pneumoniae, 50% for Moraxella catarrhalis and 14% for Haemophilus influenzae. Colonisation with S.aureus diminished over time and was more common in HIV-infected infants. S.pneumoniae and H.influenzae colonisation rose over time and was more prevalent in HIV-uninfected children. Co-colonisation of S.pneumoniae with H.influenzae or M.catarrhalis was mostly noticed in HIV-infected infants. S.pneumoniae and M.catarrhalis colonisation of the mother was a risk factor for colonisation in HIV-uninfected infants, while maternal S.aureus colonisation was a risk factor for colonisation in HIV-infected infants. Among the 104 S.pneumoniae isolates, 19F was most prevalent, and 57 (55%) displayed capsular serotypes represented in the 13-valent pneumococcal conjugate vaccine. NPBC was common in Tanzanian HIV-exposed infants. The significant prevalence of pneumococcal vaccine serotypes colonising this paediatric population justifies the use of the 13-valent pneumococcal vaccine to reduce the burden of pneumococcal invasive disease.