Impact of sputum gross appearance and volume on smear positivity of pulmonary tuberculosis: a prospective cohort study

Effect of sputum quality and role of Xpert® MTB/ RIF assay for detection of smear-negative pulmonary tuberculosis in same-day diagnosis strategy in Addis Ababa, Ethiopia

Background

There is limited information on the performance of the Xpert® MTB/RIF test for diagnosis of smear-negative pulmonary tuberculosis (SNPT) and rifampicin resistance (RR) in the same-day diagnosis approach. The effects of sputum quality and other factors affecting the Xpert performance are also under-investigated.

Objective

This study aimed to determine the performance of the Xpert® MTB/RIF test for detection of SNPT and RR in the same-day diagnosis strategy and the effect of sputum quality and other factors on its performance.

Methods

A cross-sectional study was conducted from August 2017 to January 2018 across 16 health facilities in Addis Ababa, Ethiopia. Two spot sputum samples were collected from 418 presumptive SNPT patients, tested with Xpert® MTB/RIF, then compared to tuberculosis culture. Additionally, culture isolates were tested for RR by BACTEC MGIT™ 960 drug susceptibility testing (DST) and MTBDRplus version 2.

Results

The Xpert® MTB/RIF test detected 24 (5.7%) SNPT cases, with a sensitivity of 92.3% (75.9% - 97.9%) and specificity of 99.2% (97.8% - 99.7%) compared with tuberculosis culture. Xpert® MTB/RIF also detected three (11.58%) RR strains with 100.0% concordance with BACTEC MGIT™ 960 DST and MTBDRplus results. Three blood-stained SNPT samples were positive by Xpert (30.0%), which was 6.9 times higher compared to salivary sputum (odds ratio: 6.9, 95% confidence interval: 1.36-34.96, p = 0.020).

Conclusion

The performance of the Xpert® MTB/RIF to detect SNPT and RR in same-day diagnosis is high. However, SNPT positivity varies among sputum qualities, and good sample collection is necessary for better test performance.

Controlling Droplet Marangoni Flows to Improve Microscopy-Based TB Diagnosis

In developing countries, the most common diagnostic method for tuberculosis (TB) is microscopic examination sputum smears. Current assessment requires time-intensive inspection across the microscope slide area, and this contributes to its poor diagnostic sensitivity of ≈50%. Spatially concentrating TB bacteria in a smaller area is one potential approach to improve visual detection and potentially increase sensitivity. We hypothesized that a combination of magnetic concentration and induced droplet Marangoni flow would spatially concentrate Mycobacterium tuberculosis on the slide surface by preferential deposition of beads and TB–bead complexes in the center of an evaporating droplet. To this end, slide substrate and droplet solvent thermal conductivities and solvent surface tension, variables known to impact microfluidic flow patterns in evaporating droplets, were varied to select the most appropriate slide surface coating. Optimization in a model system used goniometry, optical coherence tomography, and microscope images of the final deposition pattern to observe the droplet flows and maximize central deposition of 1 μm fluorescent polystyrene particles and 200 nm nanoparticles (NPs) in 2 μL droplets. Rain-X^® polysiloxane glass coating was identified as the best substrate material, with a PBS-Tween droplet solvent. The use of smaller, 200 nm magnetic NPs instead of larger 1 μm beads allowed for bright field imaging of bacteria. Using these optimized components, we compared standard smear methods to the Marangoni-based spatial concentration system, which was paired with magnetic enrichment using iron oxide NPs, isolating M. bovis BCG (BCG) from samples containing 0 and 10³ to 10⁶ bacilli/mL. Compared to standard smear preparation, paired analysis demonstrated a combined volumetric and spatial sample enrichment of 100-fold. With further refinement, this magnetic/Marangoni flow concentration approach is expected to improve whole-pathogen microscopy-based diagnosis of TB and other infectious diseases.

Reproducibility of the Ribosomal RNA Synthesis Ratio in Sputum and Association with Markers of Mycobacterium tuberculosis Burden

There is a critical need for improved pharmacodynamic markers for use in human tuberculosis (TB) drug trials. Pharmacodynamic monitoring in TB has conventionally used culture or molecular methods to enumerate the burden of Mycobacterium tuberculosis organisms in sputum. A recently proposed assay called the rRNA synthesis (RS) ratio measures a fundamentally novel property, how drugs impact ongoing bacterial rRNA synthesis. Here, we evaluated RS ratio as a potential pharmacodynamic monitoring tool by testing pretreatment sputa from 38 Ugandan adults with drug-susceptible pulmonary TB. We quantified the RS ratio in paired pretreatment sputa and evaluated the relationship between the RS ratio and microbiologic and molecular markers of M. tuberculosis burden. We found that the RS ratio was highly repeatable and reproducible in sputum samples. The RS ratio was independent of M. tuberculosis burden, confirming that it measures a distinct new property. In contrast, markers of M. tuberculosis burden were strongly associated with each other. These results indicate that the RS ratio is repeatable and reproducible and provides a distinct type of information from markers of M. tuberculosis burden.

IMPORTANCE This study takes a major next step toward practical application of a novel pharmacodynamic marker that we believe will have transformative implications for tuberculosis. This article follows our recent report in Nature Communications that an assay called the rRNA synthesis (RS) ratio indicates the treatment-shortening of drugs and regimens. Distinct from traditional measures of bacterial burden, the RS ratio measures a fundamentally novel property, how drugs impact ongoing bacterial rRNA synthesis.

Sampling strategy for bacteriological diagnosis of intrathoracic tuberculosis

BACKGROUND

Pulmonary tuberculosis (TB) is the most frequent site of TB and the one leading its spread worldwide. Multiple specimens are commonly collected for TB diagnosis including those requiring invasive procedures. This study aimed to review the sampling strategy for the microbiological diagnosis of pulmonary TB.

METHODS

A retrospective analysis of collected samples from September 1st 2014 to May 1st 2016 in the Bacteriology laboratory of Pitié-Salpêtrière Hospital (Paris, France) was performed. All the samples collected in patients aged over 18 years for the bacteriological diagnosis of pulmonary TB were included.

RESULTS

A total of 6267 samples were collected in 2187 patients. One hundred and twenty-six patients (6%) had a culture confirmed pulmonary TB. Among them, multiple sputum collections were sufficient for TB diagnosis in 63.5%, gastric lavages permitted to avoid bronchoscopy in only 7.1%, and bronchoscopy was necessary in 29.4%. The culture positivity of sputa (8.6%) was higher than that of bronchial aspirations (3.1%), bronchiolo-alveolar lavages (BAL) (2.3%) or gastric lavages (4.8%) (P<0.001). From its 70.0% theoretical PPV value, the 46.1% selection in bronchial aspirations allocated to molecular test increased PPV up to 88.9%.

CONCLUSIONS

Based on our data, we suggest to collect sputum consistently. If smear negative a bronchoscopy should be performed and molecular diagnosis be performed on a subset of bronchial aspirations based on expertise of the bronchoscopist.

Papain-cetylpyridinium chloride and pepsin-cetylpyridinium chloride; two novel, highly sensitive, concentration, digestion and decontamination techniques for culturing mycobacteria from clinically suspected pulmonary tuberculosis cases

Mycobacterial culture remains the gold standard for the diagnosis of tuberculosis. However, an appropriate digestion and decontamination method (DDM) is essential for the effective recovery of tubercle bacilli in culture. Therefore, the current study was designed to compare the performance of papain-cetylpyridinium chloride [papain-CPC] and pepsin-cetylpyridinium chloride [pepsin-CPC] DDMs against N-acetyl L-Cysteine-sodium hydroxide (NALC-NaOH) DDM for recovery of mycobacteria from clinically suspected pulmonary tuberculosis cases. To evaluate papain-CPC, pepsin-CPC and NALC-NaOH DDMs, sputum samples (N = 1381) were cultured on Löwenstein-Jensen medium and the results were compared. The papain-CPC DDM showed sensitivity, specificity, positive predictive value, and negative predictive value of 100%, 93.27%, 71.7%, and 100%, respectively as compared to NALC-NaOH DDM. Similarly, pepsin-CPC DDM demonstrated sensitivity, specificity, positive predictive value and negative predictive value of 98.94%, 94.7%, 76.11%, and 99.81%, respectively. In summary, both papain-CPC and pepsin-CPC DDMs are highly sensitive and specific techniques for recovery of mycobacteria as compared to NALC-NaOH DDM. However, when the overall performances of all DDMs compared, papain-CPC DDM isolated increased number of mycobacterial isolates with comparatively higher numbers of colonies on LJ media than both pepsin-CPC and NALC-NaOH DDMs, indicating its potential to replace the NALC-NaOH DDM for recovery of mycobacteria from sputum samples.

Pragmatic accuracy of an in-house loop-mediated isothermal amplification (LAMP) for diagnosis of pulmonary tuberculosis in a Thai community hospital

BACKGROUND

To improve the quality of diagnosing pulmonary tuberculosis (TB), WHO recommends the use of rapid molecular testing as an alternative to conventional microscopic methods. Loop-mediated isothermal amplification assay (LAMP test) is a practical and cost-effective nucleic amplification technique. We evaluated the pragmatic accuracy of an in-house LAMP assay for the diagnosis of TB in a remote health care setting where an advanced rapid molecular test is not available.

METHODS

A prospective diagnostic accuracy study was conducted. Patients with clinical symptoms suggestive of TB were consecutively enrolled from April to August 2016. Sputum samples were collected from each patient and were sent for microscopic examination (both acid-fast stain and fluorescence stain), in-house LAMP test, and TB culture.

RESULTS

One hundred and seven patients with TB symptoms were used in the final analysis. This included 50 (46.7%) culture-positive TB patients and 57 (53.3%) culture-negative patients. The overall sensitivity of the in-house LAMP based on culture positivity was 88.8% (95/107) with a 95%CI of 81.2-94.1. The sensitivity was 90.9% (40/44) with a 95%CI of 78.3-97.5 for smear-positive, culture-positive patients, and was 16.7% (1/6) with a 95%CI of 0.4-64.1 for smear-negative, culture-positive patients. The overall sensitivity of the in-house LAMP test compared to smear microscopy methods were not significantly different (p = 0.375). The specificity of the in-house LAMP based on non-TB patients (smear-negative, culture-negative) was 94.7% (54/57) with a 95%CI of 85.4-98.9.

CONCLUSIONS

The diagnostic accuracy of the in-house LAMP test in a community hospital was comparable to other previous reports in terms of specificity. The sensitivity of the in-house assay could be improved with better sputum processing and DNA extraction method.

Evaluation of factors influencing Mycobacterium tuberculosis complex recovery and contamination rates in MGIT960

BACKGROUND

Tuberculosis (TB) is a major public health problem worldwide. Contamination rate and poor recovery of Mycobacterium tuberculosis complex (MTBC) in MGIT960 culture may affect the early diagnosis of TB. Evidence is needed to determine the factors associated with contamination rates and MTBC recovery in MGIT960. Hence, we undertook this study to compare the factors influencing MTBC culture positivity and contamination rates in MGIT960 in patients with Pulmonary tuberculosis (PTB).

METHODS

A total of 849 sputum samples from newly diagnosed smear-positive TB cases enrolled into the Regional Prospective Observational Research for Tuberculosis India cohort between May 2014 to March 2017 were analyzed. Samples were inoculated into MGIT960 and positive cultures were examined for the presence of MTBC by immunochromatographic test for detection of MPT64 antigen.

RESULTS

Of the 849 cases, 811 (95.5%) were culture positive for MTBC, 23 (2.7%) were culture negative and 15 (1.8%) were contaminated. Salivary sputum showed significantly less culture yield compared to mucopurulent/blood stained samples (p = 0.021). Sputum from individuals <20 or ≥60 years showed lower culture yield of 93.9%, compared to those aged 20-59years (98.2%) (p = 0.002). Based on smear grading, culture isolation of MTBC by MGIT960 was 86.1%, 93.6% and 99.5% for negative, scanty and positive (1+/2+/3+) samples, respectively (p ≤ 0.0001). Sputum from HIV negative patients showed higher culture yield, compared to HIV positive patients (p ≤ 0.0001). Chest X-Ray revealed that patient with cavity showed higher culture isolation of MTBC compared to patients without cavity (p = 0.035). Contamination rates were higher in smear negatives (6.0%), compared to scanty (2.1%) and smear positives (1.1%) (p = 0.007). However, delay in transport of the specimen to the laboratory was the only independent factor significantly associated with increase in culture contamination.

CONCLUSION

Our results highlight that extremes of age, smear negativity, HIV infection, sputum quality and cavitation significantly influence the culture yield of MTBC, whereas transport duration and smear grading affected the contamination rates in MGIT960. Hence, addressing these factors may improve the diagnostic performance of MGIT960.

Evaluation of Loopamp Assay for the Diagnosis of Pulmonary Tuberculosis in Cambodia

The Loopamp™ MTBC kit (TB-LAMP) is recommended by WHO for Mycobacterium tuberculosis complex detection in low-income countries with a still low drug-resistant tuberculosis (TB) rate. This study is aimed at testing its feasibility in Cambodia on sputa collected from presumptive tuberculosis patients. 499 samples were tested at a smear microscopy center and 200 at a central-level mycobacteriology laboratory. Using mycobacterial cultures as reference, TB-LAMP results were compared with those of LED fluorescent microscopy (LED-FM) and Xpert® MTB/RIF. At the microscopy center, TB-LAMP sensitivity was higher than that of LED-FM (81.5% [95% CI, 74.5-87.6] versus 69.4% [95% CI, 62.2-76.6]), but lower than that of the Xpert assay (95.5% [95% CI 92.3-98.8]). At the central-level laboratory, TB-LAMP sensitivity (92.8% [95% CI, 87.6-97.9]) was comparable to that of Xpert (90.7% [95% CI, 85.0-96.5]) using stored sample. No significant difference in terms of specificity between TB-LAMP and Xpert assays was observed in both study sites. In conclusion, our data demonstrate that TB-LAMP could be implemented at microscopy centers in Cambodia to detect TB patients. In addition, TB-LAMP can be a better choice to replace smear microscopy for rapid TB diagnosis of new presumptive TB patients, in settings with relative low prevalence of drug-resistant TB and difficulties to implement Xpert assay.

Improving sputum collection processes to increase tuberculosis case finding among HIV-positive persons in Botswana

SETTING

Twenty-two human immunodeficiency virus (HIV) clinics in Botswana.

OBJECTIVE

To compare sputum collection rates, sputum quality and volume, and tuberculosis (TB) diagnosis rates before and after field efforts to improve sputum collection among individuals newly diagnosed with HIV with TB symptoms.

DESIGN

Newly diagnosed individuals living with HIV attending 22 HIV clinics in Botswana were screened for TB from August 2012 to March 2014. Starting in May 2013, a field intervention composed of the introduction of a tracking log for presumed TB patients, and patient instructions and sputum induction to improve sputum collection rates was implemented.

RESULTS

Prior to the intervention, sputum collection rates were 44.1% (384/870). Subsequently, sputum collection increased to 58.3% (579/993) (P < 0.001). Sputum quality and volume also improved. Although rates of TB diagnosis increased from 9.7% (84/870) to 12.5% (120/993), this difference was not significant (P = 0.143).

CONCLUSION

Sputum collection rates among presumptive TB cases, as well as sputum quality and volume improved after implementation of the field intervention. To improve sputum collection rates, efforts at the program level should be ongoing.

Intrinsic and extrinsic factors associated with sputum characteristics of presumed tuberculosis patients

BACKGROUND

Sputum remains the most preferred specimen for detection of Mycobacterium tuberculosis due to its non-invasive method of production. Good quality sputum specimen is essential for accurate diagnosis of pulmonary tuberculosis (PTB). It is therefore imperative to assess factors that are related to the production of sputum that is of the best quality.

OBJECTIVE

We assessed the intrinsic and extrinsic characteristics of presumed tuberculosis patients and the quality of sputum they produced.

METHODS

This was a cross-sectional study in which consenting enrolled presumed tuberculosis patients were subjected to medical examination and a structured questionnaire administered to collect clinical history, demographic information, environmental and behavioral characteristics. The enrolled participants were instructed on how to collect spot and morning sputum specimens for macroscopic and microscopic assessment to determine any association.

RESULTS

A total of 309 patients were enrolled into the study with an even distribution on gender (50.5% males). Of these, 202 (65.3%) submitted both a spot and a morning specimen for analysis. On macroscopic examination, 70% spot and 68% morning sputum were characterized as good quality (Purulent/mucoid). The factors associated (p<0.05) with quality specimen included both intrinsic and extrinsic factors. The intrinsic factors included: difficulty in breathing, presence of conjunctivitis and knowledge of the disease whereas the only extrinsic factor associated with production of good quality sputum for tuberculosis diagnosis was time taken by patient to seek tuberculosis treatment after occurrence of any of the TB symptoms.

CONCLUSION

Both intrinsic and extrinsic factors affected the quality of sputum produced by presumed tuberculosis patients. Clinical and behavioral characteristics including conjunctivitis, difficulty in breathing and delay in seeking treatment were important factors that determined the production of good quality sputum specimens, while knowledge of tuberculosis disease did not compel presumed tuberculosis patients to produce good quality sputum for diagnosis of the disease.

The effect of sputum quality and volume on the yield of bacteriologically-confirmed TB by Xpert MTB/RIF and smear

Introduction

The World Health Organization endorsed (2010) the use of Xpert MTB/RIF and countries are shifting from smear microscopy (smear)-based to Xpert MTB/RIF-based tuberculosis (TB) diagnostic algorithms. As with smear, sputum quality may predict the likelihood of obtaining a bacteriologically-confirmed TB when using Xpert MTB/RIF.

Methods

From 08/12-11/2014, all people living with HIV were recruited at 22 clinics. For patients screened positive using the four TB symptoms their sputa were tested by Xpert MTB/RIF and smear. Laboratorians assessed and recorded sputum appearance and volume. The yield of bacteriologically-positive sputum evaluated using Xpert MTB/RIF and smear, likelihood-ratios were calculated.

Results

Among 6,041 patients enrolled 2,296 were presumptive TB, 1,305 (56.8%) had > 1 sputa collected and 644/1,305 (49.3%) had both Xpert MTB/RIF and smear results. Since >1 sputa collected from 644 patients 954 sputa were tested by Xpert MTB/RIF and smear. Bacteriologically-positive sputum was two-fold higher with Xpert MTB/RIF 11.4% versus smear 5.3%, p < 0.001. Sputum appearance and quantity were not predictive of bacteriologically-positive results, except volume of 2ml to < 3ml, tested by Xpert MTB/RIF LR+= 1.26 (95% CI, 1.05–1.50).

Conclusion

Xpert MTB/RIF test yield to bacteriologically-positive sputum was superior to smear. Sputum quality and quantity, however, were not consistently predictive of bacteriologically-positive results by Xpert MTB/RIF or smear.

GeneXpert MTB/RIF Outperforms Mycobacterial Culture in Detecting Mycobacterium tuberculosis from Salivary Sputum

GeneXpert MTB/RIF (Xpert) assay has been endorsed for the diagnosis of pulmonary TB due to its high sensitivity and specificity for culture positive TB. There is no doubt that Xpert could not be more sensitive than mycobacterial culture, while the positive rate of Xpert among sputum samples was higher than that of mycobacterial culture in our laboratory. We therefore carried out a prospective study to determine a potential explanation for this unexpected result regarding the clinical use of Xpert. Overall, a total of 558 patients meeting inclusion criteria were enrolled in final analysis between August 2017 and September 2017 in Beijing Chest Hospital. The overall positive rate of Xpert among sputum samples was 45.9% (256/558), which was significantly higher than that of liquid culture (33.4%, 184/558; P < 0.01). The percentage of culture negative result in salivary sputum was significantly higher than that in mucoid sputum [odds ratio (OR): 5.04, 95% confidence interval (95% CI): 2.74–9.28; P < 0.01]. In addition, the TB cases having previous treatment history had a higher proportion of culture negative result than new cases (OR: 4.26, 95% CI: 1.61–11.28; P = 0.01). In conclusion, the results of this study demonstrate that Xpert outperforms mycobacterial culture in detecting MTB from salivary sputum. In addition, the previously treated patients are more likely to yield negative culture results. Our data will provide important hints to formulate an appropriate diagnostic algorithm for pulmonary tuberculosis based on the appearance of sputum samples.

Efficiency of the Lung Flute for sputum induction in patients with presumed pulmonary tuberculosis

INTRODUCTION

High quality sputum helps increase the sensitivity of the diagnosis of pulmonary tuberculosis.

OBJECTIVES

To evaluate the efficiency of the acoustic device (Lung Flute; LF) in sputum induction compared with the conventional method, hypertonic saline inhalation (HSI).

METHODS

In this crossover study, patients with presumed pulmonary tuberculosis submitted 3 consecutive sputa: the first sputum without induction and the second and third ones using LF and HSI. We compared the efficiency of the 2 induction methods.

RESULTS

Sixty-four participants were eligible. Thirty-five (54.6%) patients had negative smears on the first sputum without induction. Among those patients, 25.7% and 22.9% patients were smear-positive after using LF and HSI, respectively (P = .001). The positive conversion rate was not significantly different between the methods. The first samples without induction yielded 65.7% positive cultures, whereas 71.4% and 77.1% of the samples from LF and HSI were positive, respectively (P = .284). Similar results were observed in the nucleic acid amplification test [no induction (60.0%), LF (72.0%) and HSI (60.0%); P = .341]. In 29 smear-positive patients on the first sputum without induction, we observed no significant increase in smear grade, culture yield and nucleic acid amplification test positivity with either method. LF tended to induce fewer adverse events; desaturation (3.1% vs 11.1%; P = .082) and throat pain (1.5% vs 9.5%; P = .057). LF showed significantly fewer total adverse events (15.8% vs 34.9%; P = .023).

CONCLUSIONS

Our study showed LF had similar sputum induction efficiency to HSI with relatively fewer complications.

Sputum quality and diagnostic performance of GeneXpert MTB/RIF among smear-negative adults with presumed tuberculosis in Uganda

BACKGROUND

Introduction of GeneXpert MTB/RIF (Xpert) assay has constituted a major breakthrough for tuberculosis (TB) diagnostics. Several patient factors may influence diagnostic performance of Xpert including sputum quality.

OBJECTIVE

We carried out a prospective, observational, cross-sectional study to determine the effect of sputum quality on diagnostic performance of Xpert among presumed TB patients in Uganda.

METHODS

We collected clinical and demographic information and two sputum samples from participants. Staff recorded sputum quality and performed LED fluorescence microscopy and mycobacterial culture on each sample. If both smear examinations were negative, Xpert testing was performed. We calculated diagnostic yield, sensitivity, specificity, and other indicators for Xpert for each stratum of sputum quality in reference to a standard of mycobacterial culture.

RESULTS

Patients with salivary sputum showed a trend towards a substantially higher proportion of samples that were Xpert-positive (54/286, 19%, 95% CI 15-24) compared with those with all other sputum sample types (221/1496, 15%, 95% CI 13-17). Blood-stained sputum produced the lowest sensitivity (28%; 95% CI 12-49) and salivary sputum the highest (66%; 95% CI 53-77). Specificity didn't vary meaningfully by sample types. Salivary sputum was significantly more sensitive than mucoid sputum (+13%, 95% CI +1 to +26), while blood-stained sputum was significantly less sensitive (-24%, 95% CI -42 to -5).

CONCLUSIONS

Our findings demonstrate the need to exercise caution in collecting sputum for Xpert and in interpreting results because sputum quality may impact test yield and sensitivity. In particular, it may be wise to pursue additional testing should blood-stained sputum test negative while salivary sputum should be readily accepted for Xpert testing given its higher sensitivity and potentially higher yield than other sample types. These findings challenge conventional recommendations against collecting salivary sputum for TB diagnosis and could inform new standards for sputum quality.

Diagnosis of pulmonary tuberculosis using Ziehl-Neelsen stain or cold staining techniques?

BACKGROUND

Acid-fast bacilli microscopy is the first step in the diagnosis and screening of pulmonary tuberculosis (PTB) in developing countries. It remains a rapid and inexpensive diagnostic tool for diagnosing a large number of PTB cases with limited resources.

OBJECTIVE

To evaluate three different staining techniques used in the detection of acid-fast bacilli. The conventional Ziehl-Neelsen (ZN) stain and two cold stains, Gabbett's cold stain and modified cold stain (MCS), were compared with sputum culture.

MATERIALS AND METHODS

A total of 300 sputum samples from 100 clinically suspected PTB patients referred to Maamorah Chest Hospital in Alexandria, Egypt, were tested. For staining and culture, three sputum samples from each patient were collected (one 'on spot' and two early morning samples) and pooled together. Smears were prepared using three different staining methods (ZN, Gabbett's cold stain, and MCS) and were inoculated in the Lowenstein-Jensen media.

RESULTS

Comparison of sputum staining results using three different staining techniques versus culture proved that the highest sensitivity and specificity were seen for Gabbett's stain (76.6 and 98.5%, respectively). ZN stain had a sensitivity and specificity of 70 and 97.1%, whereas MCS had a sensitivity and specificity of 60 and 95.7%, respectively.

CONCLUSION

Gabbett's stain was more accurate in the diagnosis of PTB compared with both ZN and MCS, even though the results were not statistically significant. It can replace ZN for initial diagnosis and follow up of cases. It is also easier, faster, and does not require a heating step.

Long-Term Storage at -80°C: Effect on Rate of Recovery of Mycobacterium tuberculosis From Direct Acid-Fast Bacilli Smear-Positive Sputum Samples

BACKGROUND

The aim of this study was to evaluate the difference in the rate of recovery of Mycobacterium tuberculosis (MTB) from routinely cultured sputum and long-term stored sputum specimens (at -80°C) using Löwenstein-Jensen (LJ) media, Mycobacterium Growth Indicator Tube (BBL MGIT(TM) ), and Middlebrook 7H11 (MB 7H11) agar.

METHODS

Direct acid-fast bacilli smear-positive sputum specimens (both before and after storage [n = 136]) were studied (after culturing on LJ media, BBL MGIT(TM) , and MB 7H11 agar) and the performances were compared.

RESULTS

For the detection of MTB, BBL MGIT(TM) and MB 7H11 agar (before storage) demonstrated a sensitivity, specificity, positive predictive value (PPV) of 98.28%, 30.77%, 92.68%, 66.67%, and negative predictive value (NPV) of 97.41%, 30.77%, 92.62%, 57.14%, respectively, when compared to LJ media (before storage). Similarly, BBL MGIT(TM) and MB 7H11 agar (after storage) demonstrated a sensitivity, specificity, PPV, and NPV of 95.5%, 38.89%, 90.6%, 58.33%, and 95.5%, 66.67 %, 94.64%, 70.59%, respectively, when compared to LJ media (after storage) for the detection of MTB.

CONCLUSION

None of the culture techniques independently (both before and after storage) detected growth of MTB from all the sputum specimens studied. However, BBL MGIT(TM) system and LJ media combination (both before and after storage) effectively detected the growth of MTB from sputum specimens when compared to other culture technique combinations.

Diagnostic Accuracy of the Small Membrane Filtration Method for Diagnosis of Pulmonary Tuberculosis in a High-HIV-Prevalence Setting

Sputum acid-fast bacilli (AFB) smear microscopy has suboptimal sensitivity but remains the most commonly used laboratory test to diagnose pulmonary tuberculosis (TB). We prospectively evaluated the small membrane filtration (SMF) method that concentrates AFB in a smaller area to facilitate detection to improve the diagnostic performance of microscopy. We enrolled adults with suspicion of pulmonary TB from health facilities in southwestern Uganda. Clinical history, physical examination, and 3 sputum samples were obtained for direct fluorescent AFB smear, SMF, Xpert MTB/RIF, and MGIT culture media. Sensitivity and specificity were estimated for SMF, AFB smear, and Xpert MTB/RIF, using MGIT as the reference standard. The analysis was stratified according to HIV status. From September 2012 to April 2014, 737 participants were included in the HIV-infected stratum (146 [20.5%] were culture positive) and 313 were in the HIV-uninfected stratum (85 [28%] were culture positive). In HIV-infected patients, the sensitivity of a single SMF was 67.4% (95% confidence interval [CI], 59.9% to 74.1%); for AFB, 68.0% (95% CI, 60.6% to 74.6%); and for Xpert MTB/RIF, 91.0% (95% CI, 85.0% to 94.8%). In HIV-uninfected patients, the corresponding sensitivities were 72.5% (95% CI, 62.1% to 80.9%), 80.3% (95% CI, 70.8% to 87.2%), and 93.5% (95% CI, 85.7% to 97.2%). The specificity for all 3 tests in both HIV groups was ≥96%. In this setting, the SMF method did not improve the diagnostic accuracy of sputum AFB. The Xpert MTB/RIF assay performed well in both HIV-infected and -uninfected groups.

Do Instructional Videos on Sputum Submission Result in Increased Tuberculosis Case Detection? A Randomized Controlled Trial

Objective

We examined the effect of an instructional video about the production of diagnostic sputum on case detection of tuberculosis (TB), and evaluated the acceptance of the video.

Trial Design

Randomized controlled trial.

Methods

We prepared a culturally adapted instructional video for sputum submission. We analyzed 200 presumptive TB cases coughing for more than two weeks who attended the outpatient department of the governmental Municipal Hospital in Mwananyamala (Dar es Salaam, Tanzania). They were randomly assigned to either receive instructions on sputum submission using the video before submission (intervention group, n = 100) or standard of care (control group, n = 100). Sputum samples were examined for volume, quality and presence of acid-fast bacilli by experienced laboratory technicians blinded to study groups.

Results

Median age was 39.1 years (interquartile range 37.0–50.0); 94 (47%) were females, 106 (53%) were males, and 49 (24.5%) were HIV-infected. We found that the instructional video intervention was associated with detection of a higher proportion of microscopically confirmed cases (56%, 95% confidence interval [95% CI] 45.7–65.9%, sputum smear positive patients in the intervention group versus 23%, 95% CI 15.2–32.5%, in the control group, p <0.0001), an increase in volume of specimen defined as a volume ≥3ml (78%, 95% CI 68.6–85.7%, versus 45%, 95% CI 35.0–55.3%, p <0.0001), and specimens less likely to be salivary (14%, 95% CI 7.9–22.4%, versus 39%, 95% CI 29.4–49.3%, p = 0.0001). Older age, but not the HIV status or sex, modified the effectiveness of the intervention by improving it positively. When asked how well the video instructions were understood, the majority of patients in the intervention group reported to have understood the video instructions well (97%). Most of the patients thought the video would be useful in the cultural setting of Tanzania (92%).

Conclusions

Sputum submission instructional videos increased the yield of tuberculosis cases through better quality of sputum samples. If confirmed in larger studies, instructional videos may have a substantial effect on the case yield using sputum microscopy and also molecular tests. This low-cost strategy should be considered as part of the efforts to control TB in resource-limited settings.

Trial Registration

Pan African Clinical Trials Registry PACTR201504001098231

Quality of Sputum Specimen Samples Submitted for Culture and Drug Susceptibility Testing at the National Tuberculosis Reference Laboratory-Uganda, July-October 2013

Setting

The Uganda National Tuberculosis Reference Laboratory (NTRL) in Kampala.

Objective

The proportion of poor quality specimens received for drug susceptibility testing (DST) at the NTRL and factors contributing to poor specimen quality were assessed.

Design

A cross-sectional study was conducted of sputum samples received at the NTRL from patients at high risk for multidrug-resistant tuberculosis (MDR TB) during July-October 2013. Demographic, clinical, and bacteriological data were abstracted from laboratory records. A poor quality sample failed to meet any one of four criteria: ≥3 milliliter (ml) volume, delivered within 72 hours, triple packaged, and non-salivary appearance.

Results

Overall, 365 (64%) of 556 samples were of poor quality; 89 (16%) were not triple packaged, 44 (8%) were <3 mls, 164 (30%) were not delivered on time, and 215 (39%) were salivary in appearance. Poor quality specimens were more likely to be collected during the eighth month of TB treatment (OR = 2.5, CI = 1.2 - 5.1), from the East or Northeast zones (OR = 2.2, CI = 1.1 - 4.8), and from patients who previously defaulted from treatment (OR = 1.9, CI = 1.1 - 3.2).

Conclusion

The majority of sputum samples had poor quality. Additional efforts are needed to improve quality of samples collected at the end of treatment, from East and Northeast zones, and from patients who had previously defaulted.

Acceptability of sputum specimens for diagnosing pulmonary tuberculosis

The evaluation of the quality of a sputum specimen prior to bacterial culture has been an accepted practice. However, optimal sputum criteria for pulmonary tuberculosis (TB) are not well established. We investigated indicators for sputum acceptability in tuberculosis cultures and acid-fast bacilli (AFB) smear. A post-hoc analysis of a randomized trial with 228 sputum specimens from 77 patients was conducted. In the trial, pulmonary TB suspects were requested for collecting three sputum specimens. We performed both TB study (AFB smear and M. tuberculosis culture) and Gram staining in each specimen. By using generalized estimating equations, the association between sputum characteristics and positive TB testings were analyzed. Although acceptable specimens for bacterial pneumonia showed higher TB-culture positive rates than unacceptable specimens (adjusted odds ratio [aOR]=1.66; 95% confidence interval [CI]=1.11-2.49), a specimen with ≥25 white blood cells/low-power field was the better predictor for positive M. tuberculosis cultures (aOR=2.30; 95% CI=1.48-3.58) and acid-fast bacilli smears (aOR=1.85; 95% CI=1.05-3.25). Sputum leukocytosis could be an indicator of sputum acceptability for diagnosing pulmonary tuberculosis.

Sputum volume predicts sputum mycobacterial load during the first 2 weeks of antituberculosis treatment

Disease severity in patients with pulmonary tuberculosis is associated with mycobacterial sputum load. To ascertain whether reduced sputum production during treatment is a useful clinical sign of improvement, we analyzed the mycobacterial loads of 5,552 sputum samples collected from 439 newly diagnosed sputum smear-positive tuberculosis patients who participated in six 14-day studies of antituberculosis treatment. Sputum volumes were categorized as low (<6 ml), medium (6 to 10 ml), or large (>10 ml), and mycobacterial load was measured by the time to positivity in liquid culture and the CFU counts on solid culture. The association of sputum volume with mycobacterial load was estimated with multiple linear regression models adjusted for repeated measures. The predictor variables were sputum volume category, treatment day, specific study , and the interaction of sputum volume category and treatment day. Mycobacterial load was significantly associated only with the day on treatment and sputum volume, which tended to decrease with ongoing treatment. With the volume held constant, each day on treatment decreased the log CFU by 0.082 (P<0.001) and increased the time to positivity (TTP) by 1.04 h (P<0.001). From low to medium and from medium to large sputum volumes, the log CFU/ml increased by 0.265 (P<0.003) and 0.490 (P<0.001), respectively, and the TTP decreased by 1.17 h (P<0.001) and 1.30 h (P<0.001), respectively, for a given day of treatment. The variability of the sputum load measurements increased with the day of treatment and lower sputum volumes. The significant association of sputum volume and mycobacterial load validates decreasing sputum production as a clinical sign of improvement during early antituberculosis treatment.

Prospective cross-sectional evaluation of the small membrane filtration method for diagnosis of pulmonary tuberculosis

Smear microscopy has suboptimal sensitivity, and there is a need to improve its performance since it is commonly used to diagnose tuberculosis (TB). We prospectively evaluated the diagnostic accuracy of the small membrane filtration (SMF) method, an approach that uses a vacuum manifold and is designed to concentrate bacilli onto a filter that can be examined microscopically. We enrolled hospitalized adults suspected to have pulmonary TB in Kampala, Uganda. We obtained a clinical history and three spontaneously expectorated sputum specimens for smear microscopy (direct, concentrated, and SMF), MGIT (mycobacterial growth indicator tube) 960 and Lowenstein-Jensen (LJ) cultures, and Xpert MTB/RIF testing. We performed per-specimen (primary) and per-patient analyses. From October 2012 to June 2013, we enrolled 212 patients (579 sputum specimens). The participants were mostly female (63.2%), and 81.6% were HIV infected; their median CD4 cell count was 47 cells/μl. Overall, 19.0%, 20.4%, 27.1%, 25.2%, and 25.9% of specimens tested positive by direct smear, concentrated smear, MGIT culture, LJ culture, and Xpert test, respectively. In the per-specimen analysis, the sensitivity of the SMF method (48.5%; 95% confidence interval [CI], 37.4 to 59.6) was lower than those of direct smear (60.9%; 51.4 to 70.5 [P = 0.0001]) and concentrated smear (63.3%; 53.6 to 73.1 [P < 0.0001]). Subgroup analyses showed that SMF performed poorly in specimens having a low volume or low bacterial load. The SMF method performed poorly compared to standard smear techniques and was sensitive to sample preparation techniques. The optimal laboratory SMF protocol may require striking a fine balance between sample dilution and filtration failure rate.

Serum complement C4b, fibronectin, and prolidase are associated with the pathological changes of pulmonary tuberculosis

Background

Mycobacterium tuberculosis infection can activate the immune system, leading to characteristic pathological changes such as inflammatory granuloma, caseous necrosis, and cavity formation.

Methods

Clinical data of 187 cases of pulmonary tuberculosis (PTB) were analyzed using statistical methods, while serum levels of complement C4b (C4b), fibronectin (FN), and prolidase (PEPD) were detected using the ELISA method among the control, minimal PTB, moderate PTB, and advanced PTB groups.

Results

We found significantly higher levels of serum C4b and PEPD (P = 0.018, P = 0.003), and significantly lower levels of serum FN (P < 0.001) in PTB patients. Furthermore, the serum levels of 3 proteins were significantly different among 3 PTB groups. FN level was significantly higher in the moderate PTB group, compared with patients in the minimal and advanced PTB groups (P < 0.05, P < 0.01). PEPD level was significantly higher in the moderate PTB group, compared with the minimal PTB group (P < 0.05). Analysis of clinical data showed that serum albumin, C-reactive protein (CRP), prealbumin, and C4 were significantly higher (P < 0.05), while serum globulin was significantly lower in patients with PTB (P < 0.001). A significant negative correlation was found between C4b and albumin, prealbumin. On the other hand, a significant positive correlation was found between C4b and globulin, CRP, PEPD, as well as between PEPD and CRP (P < 0.05).

Conclusions

Our study showed that C4b, FN, and PEPD are associated with tissue damage, granuloma formation, and cavity formation, respectively, in patients with PTB. The present study provides a new experimental basis to understand the pathogenesis and pathological changes of PTB.

Impact of sputum quality and quantity on smear and culture positivity: findings from a tuberculosis prevalence study in central India

BACKGROUND

The objective of this study was to assess the impact of sputum quality and quantity on smear and culture positivity for Mycobacterium tuberculosis.

METHODS

A total of 14 708 sputum specimens, collected from respiratory symptomatics in a TB prevalence survey, were evaluated for gross appearance and volume of sputum and examined by smear microscopy and culture.

RESULTS

The smear and culture positivity increased with the quantity and the up gradation in quality of sputum, and the difference was significant.

CONCLUSION

The study highlights the importance of visual screening of sputum specimens in the detection of pulmonary TB particularly in resource limited settings.

Audit of the practice of sputum smear examination for patients with suspected pulmonary tuberculosis in Fiji

BACKGROUND

In Fiji, patients with suspected pulmonary tuberculosis (PTB) currently submit three sputum specimens for smear microscopy for acid-fast bacilli, but there is little information about how well this practice is carried out.

METHODS

A cross-sectional retrospective review was carried out in all four TB diagnostic laboratories in Fiji to determine among new patients presenting with suspected PTB in 2011: the quality of submitted sputum; the number of sputum samples submitted; the relationship between quality and number of submitted samples to smear-positivity; and positive yield from first, second and third samples.

RESULTS

Of 1940 patients with suspected PTB, 3522 sputum samples were submitted: 997 (51.4%) patients submitted one sample, 304 (15.7%) patients submitted two samples and 639 (32.9%) submitted three samples. Sputum quality was recorded in 2528 (71.8%) of samples, of which 1046 (41.4%) were of poor quality. Poor quality sputum was more frequent in females, inpatients and children (0-14 years). Good quality sputum and a higher number of submitted samples positively correlated with smear-positivity for acid-fast bacilli. There were 122 (6.3%) patients with suspected PTB who were sputum smear positive. Of those, 89 had submitted three sputum samples: 79 (89%) were diagnosed based on the first sputum sample, 6 (7%) on the second sample and 4 (4%) on the third sample.

CONCLUSION

This study shows that there are deficiencies in the practice of sputum smear examination in Fiji with respect to sputum quality and recommended number of submitted samples, although the results support the continued use of three sputum samples for TB diagnosis. Ways to improve sputum quality and adherence to recommended guidelines are needed.