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pISSN 2384-2458 eISSN 2288-7261
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Original Article

J Lab Med Qual Assur 2020; 42(1): 33-39

Published online March 31, 2020


Copyright © Korean Association of External Quality Assessment Service.

Clinical Analysis of Sputum Gram Stains and Cultures to Improve the Quality of Sputum Cultures

Dong-Hyun Lee1 and Sunjoo Kim2

1Department of Laboratory Medicine, Gyeongsang National University Hospital, Jinju; 2Department of Laboratory Medicine, Gyeongsang National University Changwon Hospital, Changwon, Korea

Correspondence to:Sunjoo Kim
Department of Laboratory Medicine, Gyeongsang National University Changwon Hospital, 11 Samjeongja-ro, Seongsan-gu, Changwon 51472, Korea
Tel +82-55-214-3072 Fax +82-55-214-3087 E-mail sjkim8239@hanmail.net

Received: November 3, 2019; Revised: December 21, 2019; Accepted: January 6, 2020

This is an Open Access article distributed under the terms of the Creative Commons Attribution Non-Commercial License (http://creativecommons.org/licenses/by-nc/3.0) which permits unrestricted non-commercial use, distribution, and reproduction in any medium, provided the original work is properly cited.


Background: Sputum Gram stains and cultures are standard tests for the diagnosis of lower respiratory tract infections. Analysis reports of the sputum quality are scarce in relation to cultures as well as clinical diagnosis.
Methods: A total of 1,523 sputum specimens, requested for culture, were evaluated for their quality using the modified Murray–Washington (MW) grouping system in association with the culture results. The clinical diagnosis was investigated for the culture positive cases.
Results: There was a significant difference in bacterial growth (odds ratio, 2.01; P=0.0164) and diagnosis of pneumonia (odds ratio, 4.18; P=0.002) between the acceptable groups (groups 4–5) and the unacceptable groups (groups 1–3). However, one-quarter did not belong to the current MW group. More than half of the sputum cultures were in group 6, with the lowest positive rate (18.0%). Overall, 10% of the sputum cultures were related to a clinical diagnosis of pneumonia.
Conclusions: The MW grouping system should be revised, because one-quarter did not belong to the current group. Further evaluation of group 6 will be needed. Improvement of sputum cultures is required to enhance the diagnosis of pneumonia.

Keywords: Pneumonia, Culture, Streptococcus pneumoniae, Quality improvement

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