Background
Most studies have focused on either healthcare worker collected (HCWC) or self-collected (SC) tongue swabs (TS) for detecting Mycobacterium tuberculosis, but rarely on both. We assessed this, on TS collected from the same participant, using the Xpert MTB/RIF Ultra (Ultra) (Cepheid, Sunnyvale, CA, USA) along with participant acceptability of the collection procedure.
Methods
In this cross-sectional study, 669 participants who met eligibility were consented and enrolled at eight healthcare facilities in the Ekurhuleni District of Johannesburg, South Africa. Sputum was tested on Ultra and mycobacterial growth indicator tube (MGIT) culture and two TS (HCWC and SC) tested on Ultra. A total of 314 participants used a short-shaft (4 cm) spun polyester XpressCollectTM swab (Steripack), while 355 participants used a longer-shaft (15 cm) Copan FLOQ swab (Copan Italia S.p.A.). Sputum and swabs (dry) were transported at 2-8°C to the laboratory and TS results were compared to MGIT. Participant observations on TS feasibility and usability were noted.
Results
Valid results on all assays were available from 520 participants for statistical analysis. The median age was 41 years (54% male), 47% were HIV-positive and 7% bacteriologically confirmed using MGIT. In comparison to MGIT, test sensitivities for both HCWC and SC TS were 68.3% (95% CI: 51.9%-81.9%), with specificities of 99.4% (95% CI: 98.2%-99.9%) and 99.8% (95% CI: 98.8%-100%), respectively. Test error rates for the HCWC and SC TS were 21/666 (3.2%) and 23/669 (3.4%), respectively. Most participants (89%) were comfortable with TS collection and confident with self-collection, however participants using XpressCollectTM reported difficulty with collection due to the short swab shaft. Preferences among participants for swab collection were: 149/668 (22%) preferred SC and 230/668 (34%) preferred HCWC, while 289/668 (43%) had no preference.
Conclusions
Both HCWC and SC TS showed comparable sensitivity and high specificity compared to MGIT with low error rates, demonstrating that TS is a viable specimen type for TB detection in clinical settings. Majority participants expressed comfort with TS collection and confidence in self-collection, highlighting the acceptability of this method, although swab design was shown to affect usability. The preference data suggests that both self-collection and HCW-collection are suitable options, offering flexibility for patient-centered care.