Urinary pneumococcal antigen testing ‘useful in children’

Urinary antigen testing is effective in detecting invasive pneumococcal pneumonia in children, say the authors of a UK-based case–control study.

The study involved 160 children under the age of 16 years (median 2.6 years) with radiologically confirmed pneumonia, and 122 control children who gave urine samples while attending the pediatric renal service.

The team, led by Mohamed Elemraid from the Great North Children’s Hospital in Newcastle upon Tyne, found that children with pneumonia were significantly more likely to test positive for urinary pneumococcal antigen than controls, at 28.3% versus 7.4%. This finding was also true among the youngest patients, under the age of 5 years, for whom the respective rates were 23.5% and 9.5%.

Microbiologic and virologic testing confirmed Streptococcus pneumoniae as the cause of pneumonia in 24 patients and, when 20 of these children underwent urinary antigen testing, 15 (75%) had a positive result.

The researchers also note that there was no association between S. pneumoniae detection in nasopharyngeal secretion and pneumococcal urinary antigen detection, leading them to conclude that in children for whom the former is negative and the latter is positive, invasive pneumococcal disease is more likely than carriage.

“We suggest that urinary pneumococcal antigen testing may be a useful investigation to help establish rapid diagnosis of invasive pneumococcal disease, particularly in low-resource countries where expensive PCR [polymerase chain reaction]-based assays are not readily available,” the authors write in Clinical Pediatrics.

“Used in this way this test may also prove a useful tool in clinical management and studies of the epidemiology of childhood pneumonia,” they conclude.

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