Hospital-based surveillance of pneumonia is an emerging method for monitoring pneumococcal conjugate vaccine (PCV) effectiveness, especially in low resource settings like Timor-Leste. We assessed the impact of antibiotic use on nasopharyngeal carriage of S. pneumoniae (SPN).
Pulmaun Saudavel is an ongoing pre-PCV surveillance study of children 1-59 months hospitalised with pneumonia and/or malnutrition. Nasopharyngeal swabs were collected as soon as practical after admission and cultured. Antibiotic exposure was classified as prehospital (by parent report) and in-hospital (from the medical record).
Of 160 cases enrolled between September 2019 and January 2020, 43 (26%) had NP carriage of SPN. Carriage was higher among cases without any antibiotic exposure (15/27, 56%), compared to those with any antibiotic exposure (28/133, 21%; p<0.01). While there was no difference in carriage between those with and without prehospital exposure (24% vs 30%, p=0.39), those with swab collected <12hrs after in-hospital exposure had higher carriage compared to those with swab collected >12hrs (50% vs 19%, p=0.034). This remained significant in a logistic regression adjusted for age and sex (p=0.047).
Antibiotic exposure is associated with reduced NP carriage of SPN. Hospital-based studies should attempt to collect NP swabs within 12 hours of first antibiotic dose.