Drug‐resistant genes and serotypes of pneumococcal strains of community‐acquired pneumonia among adults in Japan

Abstract

Background: A high frequency of drug‐resistant pneumococci has been reported in Asian countries. Few data on the drug‐resistance or serotype of pneumococcal strains responsible for community‐acquired pneumonia (CAP), however, are available for the past two decades in Japan. Methodology: Susceptibility to antibiotics and the genotype of antibiotic‐resistant genes and serotypes of Streptococcus pneumoniae isolates from 114 adult patients with CAP were examined in a nationwide study in Japan between 2001 and 2003. Results: Most of the cases were non‐bacteraemic pneumonia and the case fatality rate was 4.4%. The most frequent genotype of the pbp gene was pbp1a + 2x + 2b (gPRSP; 36.8%) followed by pbp 2x (28.1%) and of the macrolide‐resistant gene, it was ermB (50.0%). The most common serotype was 19F (29.1%), followed by serotype 23F (13.2%), 6B (12.3%) and 3 (11.4%). The coverage of serotypes of isolates by a 23‐valent pneumococcal polysaccharide vaccine (PPV) would be 82.5% in these patients with CAP. Most of strains with serotypes 19F and 23F were gPRSP. A cluster of serotype 3 strains associated with the pbp 2x and ermB gene was also noted. Conclusion: A high frequency of altered pbp gene mutations or of macrolide‐related genes and a high serotype coverage by the 23‐valent PPV found in our study of pneumococcal pneumonia facilitates attempts to increase the coverage rate of the 23‐valent PPV in adults older than 65 years in Japan.