Pneumococcal Acute Otitis Media in Infants and Children in Central Romania, 2009-2011: Microbiological Characteristics and Potential Coverage by Pneumococcal Conjugate Vaccines

Objective: To assess the epidemiological and microbiological characteristics of pneumococcal acute otitis media (AOM) in children in Brasov, Central Romania, before the introduction of pneumococcal conjugate vaccine (PCV) into the routine national immunization program.

Methods: All AOM patients aged <5 years who underwent tympanocentesis or presented with purulent otorrhea of ≤24h duration during 2009-2011 were enrolled.

Results: Two hundred and twelve consecutive AOM patients had a middle ear fluid (MEF) culture performed; 99 (46.6%) episodes occurred in patients <12 months of age. One hundred and eleven (52.4%) episodes were culture-positive. Tympanocentesis was performed in 142 patients and spontaneous otorrhea cultures in 70 patients. Overall, 114 pathogens were recovered: Streptococcus pneumoniae was the most common isolate (81 isolates, 70.3% of all culture-positive episodes), followed by non-typeable Haemophilus influenzae (26, 20.7%), Streptococcus pyogenes (5, 4.5%), and Moraxella catarrhalis (2, 1.8%). Antibiotic susceptibility and serotyping were performed for 48 (59.3%) S. pneumoniae isolates: 45 (93.8%) were non-susceptible to penicillin (minimal inhibitory concentration (MIC) ≥2.0μg/ml in 24, 53.3%) and 37 (77.1%) isolates had ceftriaxone MIC values ≥0.5μg/ml (16 with MIC >2.0μg/ml). S. pneumoniae non-susceptibility rates to trimethoprim-sulfamethoxazole, erythromycin, and clindamycin were 75.0%, 58.3%, and 35.4%, respectively. All isolates were susceptible to chloramphenicol. Multidrug resistance was found in 33 (68.7%) isolates. The most common S. pneumoniae serotypes were 19F (14, 29.2%), 6B (8, 16.7%), 23F (8, 16.7%), and 14 (6, 12.5%). Serotype 19A was found in three (6.2%) patients and 6A in two (4.1%). Non-PCV13 serotypes represented six (12.6%) of all serotypes (four of them non-susceptible to penicillin). Thirty-six (75.0%) isolates were potentially covered by PCV7, 37 (77.0%) by PCV10, and 42 (87.5%) by PCV13.

Conclusions: (1) S. pneumoniae was the most prevalent pathogen, with frequent antibiotic resistance and multi-resistance patterns; (2) most pneumococcal AOM and multidrug-resistant episodes could be prevented by PCVs.