Bacterial aetiology of otitis media in children in Pakistan aged 0–59 months; laboratory surveillance data from 2004 to 2013: comparison between before and after the introduction of Hib vaccination

Otitis media (OM) is a leading cause of childhood illness. In Pakistan, the estimated incidence of OM-associated hearing impairment is &gt;40/10,000 population and OM-associated mortality is 50–79·9/10×10⁶ population. No OM microbiology data are available from Pakistan since 2004. To describe the microbiology of OM in children aged 0–59 months in Pakistan. Laboratory data on ear pus specimens taken from children seen between 2004 and 2013 were retrieved from the Laboratory Information Systems of the Aga Khan University and entered into Microsoft Excel and SPSS version 16.0. Bacterial culture results from 277 specimens were analysed. <i>Staphylococcus aureus</i> and <i>Pseudomonas aeruginosa</i> were the organisms most commonly isolated, followed by <i>Streptococcus pneumoniae</i> and <i>Haemophilus influenzae</i>. Polymicrobial cultures significantly increased in the post-Hib vaccination period from 19·5% to 32·7% (<i>P</i> = 0·038). <i>H. influenzae</i> also increased significantly from 16·8% to 24·5% (<i>P</i> = 0·038). An increase in <i>H. influenzae</i> may reflect non-b capsular types (not determined in the study), or even capsular types from areas with low vaccine coverage. Increases in polymicrobial cultures and <i>H. influenzae</i> warrant further study.