A Longitudinal Study of Streptococcus pneumoniae Carriage in a Cohort of Infants and Their Mothers on the Thailand-Myanmar Border

Abstract

BackgroundPneumococcal disease is a major cause of childhood death. Almost a third of the world's children live in Southeast Asia, but there are few data from the region on pneumococcal colonization or disease. Our aim was to document the dynamics of pneumococcal carriage in a rural SE Asian birth cohort.MethodsWe studied 234 Karen mother-infant pairs in Northwestern Thailand. Infants were followed from birth and nasopharyngeal swabs were taken from mother and infant at monthly intervals until 24 months old.Results8,386 swabs were cultured and 4,396 pneumococci characterized. Infants became colonized early (median 45.5 days; 95% confidence interval [CI] 44.5-46.0) and by 24 months had a median of seven (range 0–15) carriage episodes. Maternal smoking and young children in the house were associated with earlier colonization (hazard ratio [HR] 1.5 (95% CI 1.1–2.1) and 1.4 (95% CI 1.0–1.9)). For the four commonest serotypes and non-typeable pneumococci, previous exposure to homologous or heterologous serotypes resulted in an extended interval to reacquisition of the same serotype. Previous colonization by serotypes 14 and 19F was also associated with reduced carriage duration if subsequently reacquired (HR [first reacquisition] 4.1 (95% CI 1.4–12.6) and 2.6 (1.5–4.7)). Mothers acquired pneumococci less frequently, and carried them for shorter periods, than infants (acquisition rate 0.5 vs. 1.1 /100 person-days, p<0.001; median duration 31.0 vs. 60.5 days, p = 0.001). 55.8% of pneumococci from infants were vaccine serotypes (13-valent pneumococcal conjugate vaccine, PCV13), compared with 27.5% from mothers (p<0.001). Non-typeable pneumococcal carriage was common, being carried at least once by 55.1% of infants and 32.0% of mothers.ConclusionsPneumococcal carriage frequency and duration are influenced by previous exposure to both homologous and heterologous serotypes. These data will inform vaccination strategies in this population.

Prevalence and Antibiotic Resistance Pattern of Streptococcus Pneumoniae, Isolated From Invasive and Non-Invasive Infections in a Tertiary Care Hospital of Karachi.

“…Similarly, the high prevalence found in adults and in children in our study contradicted the other report [1]. Adults and children are the most vulnerable groups carrying infections due to the decreased immune profile.…”

Evolution of antibiotic resistance is linked to any genetic mechanism affecting bacterial duration of carriage

“…For the Maela dataset, we used mean carriage duration (in infants) estimates based on longitudinal sampling in Maela by Turner et al (14) (SI Appendix, Supporting Text 5 and Dataset S1). Because longitudinal sampling was not available for Malawi and Massachusetts, we derived clearance rates (and hence mean carriage duration as the reciprocal of clearance rate) for these datasets using estimates by Lipsitch et al based on data collected in Kilifi, Kenya (17).…”

“…We computed the correlation between duration of carriage and resistance in three sets of isolates collected at different locations: Maela (13), using Maela-based duration of carriage estimates by Turner et al (14) (Dataset S1); and Massachusetts (15) and Malawi (16), using duration of carriage calculated from rates estimated by Lipsitch et al (17), based on data collected in Kilifi, Kenya (Materials and Methods). There was a significant positive correlation between resistance and duration of carriage for seven out of the eight tested dataset/antibiotic combinations (Table 1 and Fig.…”

The new first-line defense: the potential of nasopharyngeal colonization in vaccine strategies

“…6,29 Carriage prevalence depends on geographical location, and is generally higher in the developing world. [30][31][32] While initial colonization events may persist for up to 4 months, duration appears to shorten with increasing age to 2-4 weeks in adults. 33 The proportion of S. pneumoniae colonization events associated with disease is low in healthy adults.…”