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ORIGINAL ARTICLE
Year : 2019  |  Volume : 9  |  Issue : 2  |  Page : 73-74  

Impact of sputum volume in the diagnosis of smear-positive pulmonary tuberculosis


Department of Microbiology, GSL Medical College, Rajahmundry, Andhra Pradesh, India

Date of Submission11-Jan-2018
Date of Acceptance31-Jan-2019
Date of Web Publication15-Apr-2019

Correspondence Address:
Dr. T Jaya Chandra
Department of Microbiology, GSL Medical College, Rajahmundry - 533 296, Andhra Pradesh
India
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Source of Support: None, Conflict of Interest: None


DOI: 10.4103/ijabmr.IJABMR_11_18

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   Abstract 


Objective: To find the impact of sputum volume in the diagnosis of smear-positive (SP) pulmonary tuberculosis (PT) and its association with gender. Materials and Methods: The study was conducted in the Department of Microbiology, GSL Medical College. PT patients were included and informed to provide good-quality sputum; volume was not mentioned. Smears were stained by Ziehl–Neelsen technique. Based on the volume of sample submitted, the participants were divided into three groups. Chi-square test was used to find the statistical significance; P < 0.05 was considered statistically significant. Results: Volume-wise, 22, 38, and 74 participants submitted sputum, respectively, in groups, <2 mL, 2–5 mL, and >5 mL; statistically, the difference was significant (P < 0.05). The smear positivity was 13% (15), 28% (32), and 59% (68), respectively, in groups, <2 mL, 2–5 mL, and >5 mL; statistically, the difference was significant (P < 0.05). Among the missed cases, the difference was statistically significant (P < 0.05) in males and the difference was statistically not significant (P > 0.05) in females. Conclusions: Notable number of SP cases are identified in ≤5 mL sputum. Hence, sample should not be discarded/rejected if the volume is <5 mL.

Keywords: Participants, sample, sputum, volume


How to cite this article:
Chandra T J. Impact of sputum volume in the diagnosis of smear-positive pulmonary tuberculosis. Int J App Basic Med Res 2019;9:73-4

How to cite this URL:
Chandra T J. Impact of sputum volume in the diagnosis of smear-positive pulmonary tuberculosis. Int J App Basic Med Res [serial online] 2019 [cited 2019 Dec 12];9:73-4. Available from: http://www.ijabmr.org/text.asp?2019/9/2/73/256190




   Introduction Top


Smear microscopy (SM) is the standard technique for the diagnosis of pulmonary tuberculosis (PT).[1] Inability to identify drug resistance and limited utility in the diagnosis of tuberculosis (TB) in HIV are the disadvantages of SM.[2] However, this is a rapid and economical technique. Due to the advantages and nonaffordability of the patients on rapid TB diagnostic tests, in high TB burden countries such as India, Pakistan, and Sub-Saharan Africa, SM is commonly used technique.[3]

As per Rashid et al. report, 5 mL is the minimum volume of sputum required[4] for SM. With this background, a study was undertaken to find the impact of sputum volume in the diagnosis of smear-positive (SP) PT and its association with gender.


   Materials and Methods Top


The study was conducted in the Department of Microbiology, GSL Medical College, from January 2017 to November 2017. The study protocol was approved by the Institutional Ethics Committee of GSL Medical College. Informed written consent was provided by all the volunteers who participated in the study. PT patients were included in the study. Participants were provided with sterile sample containers and informed to submit good-quality sputum; volume was not mentioned. Two samples were collected with a gap of 1 h, same day approach.[5] Smears were prepared and stained by Ziehl–Neelsen staining technique. Smear preparation, staining, screening under microscope, and grading were done as per the Revised National Tuberculosis Control Programme (RNTCP) guidelines.[6]

Based on the volume of sample submitted, the participants were divided into three groups, <2 mL, 2–5 mL, and >5 mL. Chi-square test was used to find the statistical significance among the SP cases between the groups and gender; P < 0.05 was considered statistically significant.


   Results and Discussion Top


A total of 134 patients were included in the study; the male-female ratio was 1.4. Volume-wise, 22 (16%), 38 (29%), and 74 (55%) participants submitted sputum, respectively, in groups, <2 mL, 2–5 mL, and >5 mL; statistically, the difference was significant (P < 0.05). Gender-wise, in males, respectively, 17 (13%), 29 (22%), and 32 (24%) participants submitted <2 mL, 2–5 mL, and >5 mL sputum; 96% (75/78) males were aware that 5 mL is the minimum volume of sputum required for SM. Inspite of this, just 41% (32/78) males were only submitted >5 mL sputum. However, in female category, respectively, 5 (3.7%), 9 (6.8%), and 42 (31%) participants submitted <2 mL, 2–5 mL, and >5 mL sputum. All the females were aware regarding the minimum volume of sputum to be submitted for SM. By remembering that, 75% (42/56) females submitted >5 mL sample.

Of the 134 study participants, 115 were SP. Among the SP cases, the male-female ratio was 1.3. According to the sputum volume, the smear positivity (SPT) was 13% (15), 28% (32) and 59% (68), respectively, in groups, <2 mL, 2–5 mL, and >5 mL; statistically, the difference was significant (P < 0.05). In males, volume-wise, 7, 4, and 2 cases were missed, respectively, in groups, <2 mL, 2–5 mL, and >5 mL; statistically, the difference was significant (P < 0.05). In females, volume-wise, 0, 2, and 4 cases were missed, respectively, in groups, <2 mL, 2–5 mL, and >5 mL; statistically, the difference was not significant (P > 0.05).

Bhat et al.[1] reported that upgradation of sputum quality and quantity increases the SPT. Even our previous studies[7],[8],[9] were also designed in such a way that 5 mL is the minimum volume of sputum to be submitted for SM. If the volume of sputum is <5 mL, the participants were informed to submit another sample and pooled sample was used for SM. Whereas, in the field conditions, laboratory technicians usually discard/reject the sputum if the volume is <5 mL. But, as per our study findings, 41% (47/115) SP cases are identified in the groups where the sputum volume is ≤5 mL; gender-wise, it was 35 and 12, respectively, for male and female. It was mentioned in one report that the sputum volume is not critical for unconcentrated SM.[10] However, Warren et al.[11] reported that the sensitivity of SM will increase with >5 mL sputum.


   Conclusion Top


As per the current study findings, notable number of SP cases are identified in ≤5 mL sputum. Hence, sputum should not be discarded/rejected if the volume is <5 mL. In case if the smear is negative for acid-fast bacilli, as per the new RNTCP diagnostic algorithm, chest X-ray and cartridge-based nucleic acid amplification tests can be considered for the diagnosis of TB.[12] Study on confirmed PT patients and small sample size are the limitations of this research.

Acknowledgments

This paper was presented in the 72nd National Conference of Tuberculosis and Chest diseases (NATCON 2017).

Financial support and sponsorship

Nil.

Conflicts of interest

There are no conflicts of interest.



 
   References Top

1.
Bhat J, Rao V, Muniyandi M, Yadav R, Karforma C, Luke C, et al. Impact of sputum quality and quantity on smear and culture positivity: Findings from a tuberculosis prevalence study in central India. Trans R Soc Trop Med Hyg 2014;108:55-6.  Back to cited text no. 1
    
2.
Chandra TJ, Raj RS, Sharma YV. Same day sputum smear microscopy approach with modified ZN staining for the diagnosis of pulmonary tuberculosis in a microscopy centre at Rajahmundry. Indian J Med Microbiol 2014;32:153-6.  Back to cited text no. 2
[PUBMED]  [Full text]  
3.
Chandra TJ. Same day sputum smear microscopy approach for the diagnosis of pulmonary tuberculosis in a microscopy centre at Rajahmundry. Indian J Tuberc 2012;59:141-4.  Back to cited text no. 3
    
4.
Rashid I, Mabuza LH, Govender I, Pretorius D. Volume of sputum to detect acid-fast Bacilli as a measure of quality for the diagnosis of pulmonary tuberculosis at the Dr George Mukhari Hospital, South Africa. Afr J Prm Health Care Fam Med 2011;3:240-6.  Back to cited text no. 4
    
5.
Chandra TJ, Selvaraj R, Sharma YV. Same-day sputum smear microscopy for the diagnosis of pulmonary tuberculosis: Direct vs. Concentrated smear. Int J Tuberc Lung Dis 2016;20:247-51.  Back to cited text no. 5
    
6.
RNTCP Central TB Division, Directorate General of Health Services. Manual for Laboratory Technicians. New Delhi, India: Directorate General of Health Services, Ministry of Health and Family Welfare; 1998.  Back to cited text no. 6
    
7.
Chandra TJ. One-sample two-smear versus two-sample two-smear approach for the diagnosis of pulmonary tuberculosis. J Lab Physicians 2018;10:135-9.  Back to cited text no. 7
[PUBMED]  [Full text]  
8.
Chandra TJ, Selvaraj R, Sharma YV. Same day sputum smear microscopy for the diagnosis of pulmonary tuberculosis: Ziehl-Neelsen versus fluorescent staining. J Family Med Prim Care 2015;4:525-8.  Back to cited text no. 8
[PUBMED]  [Full text]  
9.
Chandra TJ. Correlation between Serum Calcium Levels and Smear Grading Among the Pulmonary Tuberculosis Patients. J Microbiol Infect Dis 2018;8(1):19-22.  Back to cited text no. 9
    
10.
Fisher M, Dolby T, Surtie S, Omar G, Hapeela N, Basu D, et al. Improved method for collection of sputum for tuberculosis testing to ensure adequate sample volumes for molecular diagnostic testing. J Microbiol Methods 2017;135:35-40.  Back to cited text no. 10
    
11.
Warren JR, Bhattacharya M, De Almeida KN, Trakas K, Peterson LR. A minimum 5.0 ml of sputum improves the sensitivity of acid-fast smear for Mycobacterium tuberculosis. Am J Respir Crit Care Med 2000;161:1559-62.  Back to cited text no. 11
    
12.
RNTCP; 2016. Available from: http://www.tbcindia.gov.in/index1.php?lang=1&level=2&sublinkid=4573&lid=3177. [Last accessed on 2017 Jun 17].  Back to cited text no. 12
    




 

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