MBC value of serotypes 1 and 3.

<div><p>Community-acquired pneumonia is caused primarily by bacterial infection. For years, antibiotic treatment has been the standard of care for patients with bacterial pneumonia, although the emergence of antimicrobial-resistant strains is recognized as a global health issue. The traditional herbal medicine <i>Kampo</i> has a long history of clinical use and is relatively safe in treating various diseases. However, the antimicrobial effects of <i>Kampo</i> products against pneumonia-causative bacteria remain largely uncharacterized. In this study, we investigated the bacteriological efficacy of 11 <i>Kampo</i> products against bacteria commonly associated with pneumonia. Sho-saiko-To (9), Sho-seiryu-To (19), Chikujo-untan-To (91) and Shin’i-seihai-To (104) inhibited the growth of <i>S</i>. <i>pneumoniae</i> serotype 3, a highly virulent strain that causes severe pneumonia. Also, the growth of <i>S</i>. <i>pneumoniae</i> serotype 1, another highly virulent strain, was suppressed by treatment with Sho-saiko-To (9), Chikujo-untan-To (91), and Shin’i-seihai-To (104). Minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) against these strains ranged from 6.25–50 mg/mL and 12.5–25 mg/mL, respectively. Furthermore, Sho-saiko-To (9), Chikujo-untan-To (91), and Shin’i-seihai-To (104) suppressed the growth of antibiotic-resistant <i>S</i>. <i>pneumoniae</i> isolates. Additionally, Sho-saiko-To (9) and Shin’i-seihai-To (104) showed growth inhibition activity against <i>Staphylococcus aureus</i>, another causative agent for pneumonia, with MIC ranging from 6.25–12.5 mg/mL. These results suggest that some <i>Kampo</i> products have antimicrobial effects against <i>S</i>. <i>pneumoniae</i> and <i>S</i>. <i>aureus</i>, and that Sho-saiko-To (9) and Shin’i-seihai-To (104) are promising medicines for treating pneumonia caused by <i>S</i>. <i>pneumoniae</i> and <i>S</i>. <i>aureus</i> infection.</p></div>