Background: Lower respiratory tract infections are among the leading causes of death in children but diagnosis and defining aetiology are challenging. Up to quarter of children treated for pulmonary tuberculosis (PTB), have microbiologically confirmed TB; most are treated based on clinical and radiological features. We wished to identify the presence of other potential respiratory pathogens in nasopharyngeal samples from children presenting for care with symptoms suggestive of tuberculosis.
Methods & Materials: Nasopharyngeal swabs were collected from a cohort of children presenting with suspected PTB to Red Cross War Memorial Children's Hospital, Cape Town, South Africa, from July 2011 through to May 2012. Total nucleic acid was extracted and screened for the presence of 33 common respiratory pathogens using a multiplex real-time PCR assay, which includes probes for 21 viral, 11 bacterial and one fungal pathogen. Mycobacterial liquid culture was performed on sputum obtained from each participant. Children were categorised as definite TB (culture confirmed), not TB (improvement without TB treatment on follow-up) and possible TB (all others)
Results: Nasopharyngeal swabs were obtained from 214 children, median age 36 months (interquartile range, [IQR] 5 – 17 months). Overall, 34 (16%) of the children had definite TB, 86 (40%) had possible TB and 94 (44%) were classified as not TB. Moraxella catarrhalis (64%), Streptococcus pneumoniae (42%), Haemophilus influenzae (29%) and Staphylococcus aureus (22%) were the most common bacteria detected. Other bacteria detected include Mycoplasma pneumoniae (9%), Bordetella pertussis (7%)and ChlamydophiIa pneumoniae (4%). The most common viruses included metapneumovirus (19%), rhinovirus (15%), influenza C (9%), adenovirus (7%), cytomegalovirus (7%) and coronavirus OC43 (5.6%), the last of which was associated with definite TB (p = 0.024). M. catarrhalis and S. pneumoniae appeared concurrently in 49% of cases where at least one was detected. There was no clear difference in the distribution of respiratory pathogens between children with and without TB when assessed using linear discriminant analysis.
Conclusion: There was no clear relationship between TB categorization and coinfection/colonization with other pathogens detected. Further work is needed to explore possible pathogen interactions and determine the prevalence, in a control group of children, of nasopharyngeal colonisation with the pathogens identified.