Bacterial aetiology of non-resolving otitis media in South African children

Little is known of the aetiology, serotypes or susceptibility of the pathogens causing non-resolving otitis media in children receiving care from specialists in private practice in developed or in developing countries. Increased access to antibiotics in the community amongst children receiving such private care in South Africa may be anticipated to lead to levels of resistance similar to those found in countries with similar models of private practice, such as the United States. This study was conducted to determine the aetiology of non-resolving otitis media in South African children receiving private care and to determine the antimicrobial resistance patterns and serotypes of the bacterial isolates. Middle-ear fluid was cultured from 173 children aged two months to seven years with non-resolving acute otitis media accompanied by persistent pain or fever who were referred to otorhinolaryngologists for drainage of middle-ear fluid within 14 days of the start of symptoms. While 92 per cent of the children had recently received antibiotics and 54 per cent were currently receiving them, bacteria were isolated from 47 children (27 per cent). Streptococcus pneumoniae was the most common pathogen (35), followed by Haemophilus influenzae (nine), Staphylococcus aureus (six), Moraxella catarrhalis (two), Streptococcus pyogenes (two) and Pseudomonas aeruginosa (one). Two isolates were identified in each of eight children. Antimicrobial resistance to one or more antibiotics was found in 33/35 (94 per cent) of the pneumococci isolated, with resistance to penicillin in 86 per cent, resistance to trimethoprim-sulfamethoxazole in 54 per cent and to erythromycin and clindamycin in 69 per cent and 57 per cent, respectively. The pneumococcal serotypes found were 19F (28 per cent), 14 (26 per cent), 23F (23 per cent), 6B (nine per cent), 19A (87 per cent), and four (three per cent). Children with a bacterial pathogen isolated were younger (mean age of 17 months) than children from whom no bacteria were isolated (mean age of 23 months; p = 0.03). Isolation of a pneumococcus was also significantly associated with younger age (mean = 16 months versus 22 months, p = 0.03), the presence of fever (OR = 2.15, p = 0.049), and having one or more prior episodes of otitis media within the six months before tympanocentesis (OR = 7.72, p = 0.03). Almost all pneumococci isolated from non-resolving acute otitis media in this community are antibiotic-resistant and should be considered especially in young children who have failed previous therapy and who have non-resolving pain or fever.