An Early Morning Sputum Sample Is Necessary for the Diagnosis of Pulmonary Tuberculosis, Even with More Sensitive Techniques: A Prospective Cohort Study among Adolescent TB-Suspects in Uganda

Abstract

The World Health Organization (WHO) recommends collection of two sputum samples for tuberculosis (TB) diagnosis, with at least one being an early morning (EM) using smear microscopy. It remains unclear whether this is necessary even when sputum culture is employed. Here, we determined the diagnostic yield from spot and the incremental yield from the EM sputum sample cultures among TB-suspected adolescents from rural Uganda. Sputum samples (both spot and early-morning) from 1862 adolescents were cultured by the Lowenstein-Jensen (LJ) and Mycobacterium Growth Indicator Tube (MGIT) methods. For spot samples, the diagnostic yields for TB were 19.0% and 57.1% with LJ and MGIT, respectively, whereas the incremental yields (not totals) of the early-morning sample were 9.5% and 42.9% (P < 0.001) with LJ and MGIT, respectively. Among TB-suspected adolescents in rural Uganda, the EM sputum culture has a high incremental diagnostic yield. Therefore, EM sputum in addition to spot sample culture is necessary for improved TB case detection.

Comparison of Mycobacterium tuberculosis complex Yield and Contamination Rates using Lowenstein-Jensen with and without Antibiotics in Western Kenya

“…Interestingly, all spot 2 samples, regardless of collection as the second or third sample in a series of three, were negative on both media. These findings are consistent with previous reports suggesting the collection of two sputum, including at least one morning sample, for mycobacterial culture may be sufficient for diagnosing TB [31,32] .…”

“…Our findings also suggest samples which were documented as mucoid were more likely to be positive for MTBC when compared to salivary or tenacious samples, although this comparison is limited by the low number of tenacious samples collected. Previous authors have suggested the higher diagnostic yield observed from morning samples may reflect an accumulation of sputum in the lungs overnight resulting in a higher concentration of AFB, compared with samples collected on the spot when bacilli may be shed more sporadically [31] . We also observed more contamination in the morning sample compared with spot samples, this may be due in part to a lack of supervision during collection.…”

Feasibility of establishing a biosafety level 3 tuberculosis culture laboratory of acceptable quality standards in a resource-limited setting: an experience from Uganda

“…First, failure to use biochemical tests for identification of MTBc on LJ, instead of morphological identification methods, may have led to misidentification errors that can lead to over-estimation of MTBc recovery on LJ. However, this may not have been the case with our findings as previous studies in Uganda have indicated less need for non-morphological methods when using LJ since all growth from those studies on LJ was for MTBc [ 20 , 21 ]. Secondly, the number of samples tested during the validation period could have been small for a conclusive evidence of personnel competency and validation.…”

“…The majority of specimens processed in 2011 were from the adolescent study collected unsupervised from their homes of a distant field site to the processing laboratory. High contamination rates from unsupervised samples have also been documented in previous studies [ 19 , 20 ].…”

Half of Pulmonary Tuberculosis Cases Were Left Undiagnosed in Prisons of the Tigray Region of Ethiopia: Implications for Tuberculosis Control

“…Then, three consecutive early morning sputum samples were collected from each participant and samples were stored at -20°C for a maximum of 2–3 weeks until transported in an ice box to the Armauer Hansen Research Institute (AHRI) in Addis Ababa for culturing. We collected three early morning sputum samples instead of the routine spot-morning-spot algorithm in order to maximize the detection of undiagnosed TB cases because of that early morning sample has been shown to have a high incremental yield than spot samples [ 20 ].…”