Isaac P. Thomsen, United States of America

Vanderbilt University Medical Center Pediatrics

Author Of 2 Presentations

PNEUMOCOCCAL COLONIZATION DENSITY PATTERNS OVER TIME IN YOUNG CHILDREN IN THE PERUVIAN ANDES (ID 246)

Abstract

Background

Factors associated with nasopharyngeal pneumococcal colonization density have not been comprehensively characterized. Age, immunization status, geographical location, population density, season, and/or acute respiratory illness (ARI) may play a role. We assessed longitudinal colonization density patterns in young rural Peruvian children.

Methods

Nasopharyngeal samples were collected monthly from children aged <3 years followed prospectively each week for ARI from May 2009-September 2011. PCV7 was introduced in the region in 2009. Longitudinally-collected samples from a convenience sample of children with >=1 pneumococcus-positive sample underwent density assessment by lytA qPCR. Density values were log10-transformed to reduce skewness. Assessments were stratified by enrollment age.

Results

Pneumococcus was detected in 471/625 (75%) samples from 30 children; 20/30 (67%) were enrolled before age 1. Variability was observed in colonization densities by calendar quarter and enrollment age, with substantial overlap in density levels and trajectories over time among age groups (Figure). Median densities during ARI episodes (n=62) were 5.60 (IQR 4.36-6.24) compared to non-ARI periods (5.00 [3.98-5.93], n=409, p=0.023). fig_1_01.13.20.jpg

Conclusions

Among these children, density varied by ARI status but did not clearly decrease with age. Future trajectory analyses will assess serotype-specific density colonization patterns and the association of serotype co-colonization, vaccination, and ARI status with pneumococcal density over time.

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NASOPHARYNGEAL ANTIBIOTIC RESISTANCE GENE DETECTION IN YOUNG CHILDREN BEFORE AND AFTER ARI-ASSOCIATED ANTIBIOTIC EXPOSURE IN AN URBAN AMBULATORY SETTING IN TENNESSEE, UNITED STATES (ID 314)

Abstract

Background

Antibiotic use for acute respiratory illnesses (ARI) is very common in children, but its impact on antibiotic-resistance gene detection among nasopharyngeal (NP) bacteria is incompletely characterized.

Methods

NP samples from children <5 years of age prescribed antibiotics for ARI in ambulatory settings in Nashville, Tennessee were collected at baseline (before antibiotics) and 7 days after the encounter (follow-up). Samples were cultured for Streptococcus pneumoniae and tested for several common pneumococcal antibiotic-resistance genes by real-time PCR.

Results

To date, 7/8 (88%) children who provided paired samples received amoxicillin; 2/8 (25%) received clindamycin. Pneumococcus was detected in 5/8 (63%) baseline and 1/8 (13%) follow-up samples. Pbp2b, mef and ermB genes were detected in 4/8 (50%), 8/8 (100%) and 7/8 (88%) children at baseline, respectively. Pbp2b became undetectable at follow-up in all 4 children with baseline detection. Detection of mef and ermB remained stable or increased in 5/8 (63%) and 5/7 (71%) subjects, respectively (Figure).

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Conclusions

In this ongoing study, targeted pneumococcal antibiotic-resistance genes were commonly detected in children before antibiotic treatment and were more prevalent than pneumococcal detection, suggesting that other species may harbor these resistance mechanisms. Antibiotic use may facilitate expansion of certain resistance genes, while minimizing others.

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