The Still-Unknown Worth of a Gram Stain for Pneumonia

To the Editor—I read with great interest the recent article by Ogawa et al [1]. Despite the advent of various diagnostic tools for infectious diseases, Gram stain seems still useful in treating patients with community-acquired pneumonia due to its specificity. In addition, a Gram stain is an immediate and low-cost diagnostic tool for pneumonia [2]. The study by Ogawa et al was designed to evaluate the diagnostic accuracy of sputum Gram stain for Streptococcus pneumoniae and Haemophilus influenzae pneumonia. It should be noted that pneumococcal pneumonia is difficult to diagnose. Mainly, there are 2 points to emphasize about this issue. First, S. pneumoniae is difficult to detect from culture-based methods. This is partly due to autolysis of S. pneumoniae during the stationary growth phase. Sputum culture has been reported to be negative in about 50% of patients with bacteremic pneumococcal pneumonia [3]. Second,...