Treatment of chronic suppurative otitis media with ofloxacin in hydroxypropyl methylcellulose ear drops: a clinical/bacteriological study in a rural area of Malawi

Abstract

Chronic suppurative otitis media in young children is a major problem in Africa, with socio-economic consequences at a later age. Common treatment regimens with antibiotics are expensive and often not practically feasible. Therefore, a project was started to develop a low-cost and effective treatment in a rural area of Malawi by studying the clinical efficacy of an inexpensive application regimen of ofloxacin (0.075%) in hydroxypropyl methylcellulose (1.5%) ear drops. In earlier studies with this treatment regimen, it was possible to cure approximately 70% of ears. The aim of this study was to find out whether the bacteriological spectrum cultured from wet ears before and after treatment, and patterns of resistance to antibiotics, played a role in the percentage of cures. Patients with long-standing chronic suppurative otitis media were clinically assessed and treated with suction cleaning and instillation of ear drops on days 1, 3, 7 and 10. Bacterial swabs were taken for culture and sensitivity tests for ofloxacin were on days 1 and 10 from the ears that were still discharging. After 21 weeks, the ears were assessed again clinically. Clinical cure was considered to be complete cessation of otorrhea. Ninety of 104 tested patients (124 ears) completed the study. About 73% of the ears had become dry by day 10. This dropped to 42% after 21 weeks. Before treatment, most ears (91%) harbored fecal bacteria, Proteus mirabilis (74%) and enterococci (60%) being the most frequently isolated microbes. The second group of frequently cultured bacteria were water bacteria e.g. Pseudomonas species and other non-fermenters (69%), whereas the classical otitis media pathogens were detected only in 15% of ears. Before treatment, 9.7% of strains were resistant to ofloxacin, most (30/35) of which were cultured from ears that were eventually cured. After treatment, fecal and water bacteria were still the most frequently found, with 36% new strains and an overall sensitivity to ofloxacin of 58%. Bacterial resistance did not appear to play an important role in the outcome of treatment. These data rather suggest a very high risk of infection due to poor hygiene conditions. Medical treatment can only have a longer-lasting effect if accompanied by community-based programs that focus on improvement of hygiene. A public health approach is necessary alongside a medical approach for the management of CSOM.