Nasopharyngeal Pneumococcal Colonization Density Is Associated With Severe Pneumonia in Young Children in the Lao People's Democratic Republic

Abstract

Background: No studies have explored the association between pneumococcal nasopharyngeal density and severe pneumonia using the World Health Organization (WHO) 2013 definition. In Lao People's Democratic Republic (Lao PDR), we determine the association between nasopharyngeal pneumococcal density and severe pneumonia in children.

Methods: A prospective observational study was undertaken at Mahosot Hospital, Vientiane, from 2014 to mid-2018. Children <5 years admitted with acute respiratory infections (ARIs) were included. Clinical and demographic data were collected alongside nasopharyngeal swabs for pneumococcal quantification by lytA real-time quantitative polymerase chain reaction. Severe pneumonia was defined using the 2013 WHO definition. For pneumococcal carriers, a logistic regression model examined the association between pneumococcal density and severe pneumonia, after adjusting for potential confounders including demographic and household factors, 13-valent pneumococcal conjugate vaccine status, respiratory syncytial virus co-detection, and preadmission antibiotics.

Results: Of 1268 participants with ARI, 32.3% (n = 410) had severe pneumonia and 36.9% (n = 468) had pneumococcal carriage. For pneumococcal carriers, pneumococcal density was positively associated with severe pneumonia (adjusted odds ratio, 1.4 [95% confidence interval, 1.1-1.8]; P = .020).

Conclusions: Among children with ARIs and pneumococcal carriage, pneumococcal carriage density was positively associated with severe pneumonia in Lao PDR. Further studies may determine if pneumococcal density is a useful marker for pneumococcal conjugate vaccine impact on childhood pneumonia.

Keywords: density; nasopharynx; pneumococcus; pneumonia.

Figure 1.

Probability of severe pneumonia [11] in children aged 2–59 months admitted to hospital with an acute respiratory infection and pneumococcal carriage, Lao People’s Democratic Republic, by pneumococcal density in log₁₀ genome equivalents/mL. Severe pneumonia was defined as cough and/or difficulty breathing and tachypnea (≥50 breaths per minute for children aged 2–11 months and ≥40 breaths per minute for children aged 12–59 months) with any 1 of oxygen saturation <90%, central cyanosis, severe respiratory distress, inability to drink or breastfeed or vomiting everything, altered consciousness, and convulsions. Data adjusted for age, ethnicity, residential location, other children <5 years of age at home, cigarette smoker in house, monthly income, 13-valent pneumococcal conjugate vaccine status, coinfection with respiratory syncytial virus, and preadmission antibiotics.