Impact of Laboratory Methods, Colonization Density and Age on Detection of Streptococcus Pneumoniae in the Nasopharynx.

This study aimed to compare the performance of culture and molecular methods in detecting pneumococcus in the nasopharynx of healthy individuals and to evaluate the effects of age and colonization density on detection. Nasopharyngeal specimens were collected from healthy individuals from 2010-2012 on the Navajo Nation and White Mountain Apache Tribal lands in the United States. Pneumococci were detected by broth-enrichment culture and quantitative lytA polymerase chain reaction (qPCR). Among 982 individuals (median age: 18.7 years; male: 47%) evaluated, 3 % were culture positive and an additional 27% were qPCR positive. Agreement between culture and qPCR was 70.9%, but higher among children <18 (75.9%-84.4%) than adults ≥18 years of age (61.0%-74.6%). The mean density of colonization was lower for culture negative than positive samples (5.02 vs. 3.14 log10 copies/milliliter) overall, and for all age groups. The percent culture positive increased with increasing density, exceeding 80% above 10,000 copies/milliliter. Mean colonization density decreased with age. Use of qPCR improved detection of pneumococcus in the nasopharynx of healthy individuals. This finding was most notable among adults, likely due to improved detection of low-density colonization. PMID: 31509184 [PubMed - as supplied by publisher]
Source: Am J Epidemiol - Category: Epidemiology Authors: Tags: Am J Epidemiol Source Type: research