Pneumococcal nasopharyngeal colonization in young South Indian infants

Background. Streptococcus pneumoniae is the most frequent bacterial cause o f morbidity and mortality in young children, Bacteria carried in the nasoph arynx of healthy children reflect the prevalent strains circulating in the community. Methods. We recruited 464 newborns from a rural area in South India with en demic vitamin A deficiency. Nasopharyngeal specimens were collected from ea ch infant at ages 2, 4 and 6 months. Results. Fifty-four percent of study infants were colonized by age 2 months , with 64.1 and 70.2% carriage prevalence at ages 4 and 6 months, respectiv ely. The odds of carriage at 2 months were significantly increased in femal e infants, infants living in a household in which 20 or more cigarettes wer e smoked each day, infants whose mothers had less than 1 year of schooling and infants fed colostrum. At age 4 months infants having 2 or more sibling s <5 years of age were at significantly increased risk of carriage. At age 6 months none of the potential risk factors examined achieved statistical s ignificance, but maternal night blindness increased the risk of colonizatio n 3-fold. The odds of carrying a PncCRM(197) vaccine serotype were increase d among infants born to mothers who experienced night blindness during preg nancy. The most prevalent serogroups/types during the first 6 months of lif e were 6, 9, 10, 11, 14, 15, 19, 23 and 33, accounting for 76.7% of all ser otyped isolates. Conclusions. South Indian infants experience high rates of pneumococcal car riage during the first 6 months of life, which may partially explain their increased risk for pneumonia.