Stephen Howie (Medical Research Council Unit, Fajara, the Gambia) and team studied 55 children aged 2 to 59 months who were admitted to hospitals across the country with severe pneumonia. The pneumococcal conjugate vaccine was not routinely used during the study period (2007–2009), they note.
Forty-seven children underwent lung aspiration while nine underwent pleural aspiration. The most prevalent pathogen detected with molecular assays was S. pneumoniae, which was present in 91% of aspiration samples. Serotype-1 was the most prevalent, at 22%, followed by serotype-4 (18%), serotype-14 (18%) and serotype-5 (16%).
Haemophilus influenza was the second commonest pathogen, being detected in 23% of samples. Both H. influenza and S. pneumoniae were co-detected in 21% of samples, with H. influenza having the higher bacterial load in four of 11 cases. Two or more species were detected in 53% of all samples.
Other pathogens included commonly recognised causes of pneumonia such as Staphylococcus aureus (6%), Klebsiella species (4%), non-pneumoniae Streptococcus species (4%) and bocavirus (4%), as well rare causes such as Acinetobacter species (6%), Enterobacter species (4%) and Salmonella species (4%).
Molecular analysis detected potentially causative pathogens more frequently than did standard culture, the authors note, with detection rates of 98% and 38%, respectively.
Writing in Clinical Infectious Diseases, Howie and colleagues say that their findings are likely relevant to similar patient groups in other developing countries, especially those where conjugate pneumococcal vaccines are not used.
“The findings of this study emphasise the importance of bacteria, prominently S. pneumoniae, as a cause of severe pneumonia”, the authors conclude. “This study also confirms that molecular methods are able to detect potential pathogens far more readily than culture and have a role in defining the etiology of pneumonia.”
They add: “The challenge of accurately assigning causation to the pathogens detected remains, particularly using more generally available specimen types, and this will require the additional development of robust biomarkers of pathogen-specific disease.”
By Joanna Lyford
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