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Ideguchi S, Yamamoto K, Takazono T, Fukuda Y, Tashiro T, Shizukuishi S, Chang B, Ogawa M, Izumikawa K, Yanagihara K, Yatera K, Mukae H. Clinical features relating to pneumococcal colony phase variation in hospitalized adults with pneumonia. J Med Microbiol 2024; 73. [PMID: 38189377 DOI: 10.1099/jmm.0.001784] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2024] Open
Abstract
Background. Streptococcus pneumoniae is a major causative bacteria of pneumonia and invasive pneumococcal disease (IPD); however, the mechanisms underlying its severity and invasion remain to be defined. Pneumococcal colonies exhibit opaque and transparent opacity phase variations, which have been associated with invasive infections and nasal colonization, respectively, in animal studies. This study evaluated the relationship between the opacity of pneumococcal colonies and the clinical presentation of pneumococcal pneumonia.Methods. This retrospective study included adult patients hospitalized with pneumococcal pneumonia between 2012 and 2019 at four tertiary medical institutions. Pneumococcal strains from lower respiratory tract specimens were determined for their serotypes and microscopic colony opacity, and the association between the opacity phase and the severity of pneumonia was evaluated. Serotypes 3 and 37 with mucoid colony phenotypes were excluded from the study because their colony morphologies were clearly different.Results. A total of 92 patients were included. Most patients were older adults (median age: 72 years) and males (67 %), and 59 % had community-acquired pneumonia. Of the 92 patients, 41 (45 %), 12 (13 %), and 39 (42 %) patients had opaque, transparent, and mixed variants in their pneumococcal colony, respectively. The opaque and non-opaque pneumococcal variants had no statistically significant difference in patient backgrounds. Although the pneumonia severity index score did not differ between the opaque and non-opaque groups, the rate of bacteremia was significantly higher in the opaque group than in the non-opaque group. Serotype distribution was similar between the groups.Conclusions. Opaque pneumococcal variants may cause pneumonia and invasive diseases in humans. This study could help elucidate IPD, and opacity assessment may serve as a predictor for IPD.
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Affiliation(s)
- Shuhei Ideguchi
- First Department of Internal Medicine, Division of Infectious, Respiratory, and Digestive Medicine, University of the Ryukyus Graduate School of Medicine, Okinawa, Japan
- Department of Respiratory Medicine, Nagasaki University Hospital, Nagasaki, Japan
| | - Kazuko Yamamoto
- First Department of Internal Medicine, Division of Infectious, Respiratory, and Digestive Medicine, University of the Ryukyus Graduate School of Medicine, Okinawa, Japan
- Department of Respiratory Medicine, Nagasaki University Hospital, Nagasaki, Japan
| | - Takahiro Takazono
- Department of Respiratory Medicine, Nagasaki University Hospital, Nagasaki, Japan
| | - Yuichi Fukuda
- Department of Respiratory Medicine, Sasebo City General Hospital, Nagasaki, Japan
| | - Takahiro Tashiro
- Department of Respiratory Medicine, Kumamoto Chuo Hospital, Kumamoto, Japan
| | - Sayaka Shizukuishi
- Department of Bacteriology, National Institute of Infectious Diseases, Tokyo, Japan
| | - Bin Chang
- Department of Bacteriology, National Institute of Infectious Diseases, Tokyo, Japan
| | - Michinaga Ogawa
- Department of Bacteriology, National Institute of Infectious Diseases, Tokyo, Japan
| | - Koichi Izumikawa
- Department of Infection Control and Education Center, Nagasaki University Hospital, Nagasaki, Japan
| | - Katsunori Yanagihara
- Department of Laboratory Medicine, Nagasaki University Hospital, Nagasaki, Japan
| | - Kazuhiro Yatera
- Department of Respiratory Medicine, Hospital of the University of Occupational and Environmental Health, Japan, Fukuoka, Japan
| | - Hiroshi Mukae
- Department of Respiratory Medicine, Nagasaki University Hospital, Nagasaki, Japan
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