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.
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.
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).
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.