Prevalence of Antimicrobial-Resistant Pathogens in Middle Ear Fluid: Multinational Study of 917 Children with Acute Otitis Media

The management of acute otitis media is complicated by the emergence of resistance to β-lactam and other antibiotics among common pathogens. We conducted a large, international study of infants and children with acute otitis media to identify pathogens and susceptibility patterns. During the winter of 1994 to 1995, middle ear fluid samples were collected from 917 patients with acute otitis media in Bulgaria, the Czech Republic, Hungary, Romania, Slovakia, Israel, and the United States. A single reference laboratory performed in vitro susceptibility testing. Pathogens were isolated from 62% of the patients. ForStreptococcus pneumoniae (30% of the patients), untypeableHaemophilus influenzae (17%), andMoraxella catarrhalis (4%), there was significant variation among geographic regions (P < 0.001). The composite susceptibilities of these three organisms to amoxicillin ranged from 62% in the United States to 89% in Eastern and Central Europe; the corresponding susceptibilities to amoxicillin-clavulanate ranged from 90% in Israel to 95% in Eastern and Central Europe. β-Lactamase was produced by 31 and 100% of the isolates ofH. influenzae andM. catarrhalis , respectively. More isolates ofS. pneumoniae were susceptible to amoxicillin (90%) or amoxicillin-clavulanate (90%) than to penicillin (70%;P = 0.002). The prevalence of resistantS. pneumoniae was highest in patients less than 12 months of age.S. pneumoniae ,H. influenzae , andM. catarrhalis remain the most important bacterial pathogens in patients with acute otitis media; however, their prevalence is variable and resistance patterns are changing.