Clinical Analysis of Sputum Gram Stains andCultures to Improve the Quality of SputumCultures

ABSTRACT

Background@#Sputum Gram stains and cultures are standard tests for thediagnosis of lower respiratory tract infections. Analysis reports of the sputumquality are scarce in relation to cultures as well as clinical diagnosis. @*Methods@#A total of 1,523 sputum specimens, requested for culture, wereevaluated for their quality using the modified Murray–Washington (MW)grouping system in association with the culture results. The clinical diagnosiswas 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 lowestpositive rate (18.0%). Overall, 10% of the sputum cultures were related to aclinical diagnosis of pneumonia. @*Conclusions@#The MW grouping system should be revised, because onequarterdid not belong to the current group. Further evaluation of group 6will be needed. Improvement of sputum cultures is required to enhance thediagnosis of pneumonia.