Safety and yield of sputum induction for diagnosis of pulmonary tuberculosis in children in a tertiary hospital in Ghana

Abstract

Background: Induced sputum (IS) is a sampling technique for obtaining lower airway samples for microbial investigations, including GeneXpert and culture for microbiological confirmation of Mycobacterium tuberculosis.

Objectives: To investigate the safety and yield of IS in children admitted to a tertiary hospital in Ghana with presumed pulmonary tuberculosis (PTB).

Methods: A prospective cross-sectional study was carried out in children aged 3 months - 14 years at Komfo Anokye Teaching Hospital in Kumasi, Ghana, over the 6-month period January - June 2022. All children with breathing difficulty and other signs of respiratory distress were given respiratory support, and IS samples were obtained when respiratory distress had resolved. One or two IS samples were collected from each child within 48 hours of admission by a trained nurse after at least 4 hours of fasting. Children were monitored during and for 30 minutes after the procedure, with recording of respiratory rate, oxygen saturation, temperature and pulse rate. They were also monitored for any adverse events such as vomiting, wheezing and nosebleeds.

Results: A total of 144 children were sampled, with approximately two-thirds sampled a second time. Nearly half of the participants were aged <2 years (49.3%; n=71/144), and the median (interquartile range (IQR)) age was 2.5 (0.9 - 6.8) years. Ninety-eight children (68.1%) tested positive for PTB by Xpert Ultra, with 19/98 (19.4%) being rifampicin resistant; 47/102 (46.1%) were positive by Ziehl-Neelsen staining, and 57/102 (55.9%) were positive by Auramine O staining. Three children (2.1%) had an episode of epistaxis following the procedure. No other adverse events were observed. Measurements before and 30 minutes to 1 hour after the procedure (median (IQR)) were similar: temperature 36.5°C (36.5 - 37.5°C) v. 36.5°C (36.2 - 37.1°C), oxygen saturation 98% (92 - 99%) v. 98% (93 - 99%), pulse rate 120 (106 - 139) v. 125 (112 - 142) bpm, and respiratory rate 38 (30 - 48) v. 33 (30 - 45) cycles per minute.

Conclusion: We found sputum induction to be a safe and well-tolerated procedure in the paediatric population, with minimal clinical risk and a high microbiological yield for PTB.

Study synopsis: What the study adds. This study is the first to provide information on the performance and safety of induced sputum (IS) in Ghanaian children. It shows that IS can be performed safely in this population, despite safety concerns that resulted in its late introduction in the country. In addition, it shows that IS procedures can provide quality sputum samples to improve bacteriological confirmation of pulmonary tuberculosis (PTB) in children with presumed tuberculosis. Lastly, it adds to the existing body of literature showing that with requisite training, sputum induction can be performed in low-income settings.Implications of the findings. The study shows that the IS procedure can be used in Ghana to help shift from traditional ways of obtaining sputum samples in children, such as gastric lavage and routine methods of obtaining sputum in older children without induction, to improve bacteriological confirmation when PTB is suspected. The findings indicate that roll-out to other health facilities in Ghana is possible.

Keywords: Children; induced sputum; tuberculosis.