Emergence of a Multiresistant Serotype 19A Pneumococcal Strain Not Included in the 7-Valent Conjugate Vaccine as an Otopathogen in Children

Abstract

Context Concern has been raised about the possible emergence of a bacterial strain that is untreatable by US Food and Drug Administration (FDA)–approved antibiotics and that causes acute otitis media (AOM) in children. Objective To monitor continuing shifts in the strains of Streptococcus pneumoniae that cause AOM, with particular attention to capsular serotypes and antibiotic susceptibility, following the introduction of a pneumococcal 7-valent conjugate vaccine (PCV7). Design, Setting, and Patients Prospective cohort study using tympanocentesis to identify S pneumoniae strains that caused AOM in children receiving PCV7 between September 2003 and June 2006. All children were from a Rochester, New York, pediatric practice. Main Outcome Measure Determination of serotypes and antibiotic susceptibility of S pneumoniae causing AOM. Results Among 1816 children in whom AOM was diagnosed, tympanocentesis was performed in 212, yielding 59 cases of S pneumoniae infection. One strain of S pneumoniae belonging to serotype 19A was a new genotype and was resistant to all antibiotics approved by the FDA for use in children with AOM. This strain was identified in 9 cases (2 in 2003-2004, 2 in 2004-2005, and 5 in 2005-2006). Four children infected with this strain had been unsuccessfully treated with 2 or more antibiotics, including high-dose amoxicillin or amoxicillin-clavulanate and 3 injections of ceftriaxone; 3 had recurrent AOM; and for 2 others, the infection was their first in life. The first 4 cases required tympanostomy tube insertion after additional unsuccessful antibiotic therapies. Levofloxacin was used in the subsequent 5 cases, with resolution of infection without surgery. Conclusion In the years following introduction of PCV7, a strain of S pneumoniae has emerged in the United States as an otopathogen that is resistant to all FDA-approved antibiotics for treatment of AOM in children.