論文No3331
High prevalence of multiple serotypes of pneumococci in patients with pneumonia and their associated risk factors
Bhim Gopal Dhoubhadel, Motoi Suzuki, Tomoko Ishifuji, Makito Yaegashi, Norichika Asoh, Masayuki Ishida, Sugihiro Hamaguchi, Masahiro Aoshima, Michio Yasunami, Koya Ariyoshi, Konosuke Morimoto
Thorax 2022;77:1121-1130.
＜背景＞
肺炎球菌の複数血清型は，ワクチン以外の血清型の出現や抗菌薬耐性の獲得など，疫学的・臨床的に重要な意味を持つ。
成人における複数血清型肺炎球菌の有病率およびそのリスクファクターは不明である。
＜方法＞
日本全国の4つの病院において，放射線学的に肺炎が確認された15歳以上の成人患者を登録した。
肺炎球菌性肺炎は，lytA定量PCR法による喀痰中の肺炎球菌の菌密度が104/mL以上で定義し，血清型を決定した。
血清型が1つの肺炎を単一血清型肺炎，2つ以上の血清型を持つ肺炎を複数血清型肺炎と分類した。
多変量ロジスティック回帰を用いて危険因子を評価した。
＜結果＞
3470人の患者（年齢中央値77歳、IQR65-85）が登録された。
肺炎球菌性肺炎は476例（18.3％，n=2605）で確認された。
そのうち42%で複数の血清型が検出された。
23価肺炎球菌多糖体ワクチン（PPSV23）ワクチンの接種を受けていた患者では，
複数の血清型を持つリスクは低かった（調整済みOR 0.51（95％ CI 0.27～0.94））。
複数血清型分布における非PCV7 PPSV23血清型の割合は67.4％（n=324/481）、
単一血清型分布では46.4％（n=128/276）であった（p=0.001）。
血清型5，9N/9L，10A，12/22/46，17F，35Fは複数血清型肺炎に，
血清型6A/6B，23F，11，6C/6Dは単一血清型肺炎に関連することが示された。
また，より侵襲性の高い血清型（血清型1，5，7F，8）の比率は，多剤型肺炎で有意に高かった（p＝0.001）．
＜感想＞
成人肺炎患者の喀痰には，複数の血清型肺炎球菌が混在していた。
PPSV23ワクチン接種者における複数血清型肺炎球菌肺炎のリスクは，
単一血清型肺炎球菌肺炎のリスクよりも低いと考えられる。
臨床試験登録番号 UMIN000006909.
Background Multiple serotypes of pneumococci have epidemiological and clinical implications, such as the emergence of non-vaccine serotypes and the acquisition of antimicrobial resistance. Prevalence of multiple serotypes of pneumococci in adults and their risk factors are not known.
Methods We enrolled adult patients from age ≥15 years with radiologically confirmed pneumonia in four hospitals across Japan. Pneumococcal pneumonia was defined with a pneumococcal bacterial density of ≥104/mL in sputum by lytA quantitative PCR, and serotypes were determined. Pneumonias with a single serotype were categorised as single-serotype pneumococcal pneumonia and with two or more serotypes as multiple-serotype pneumococcal pneumonia. Multivariable logistic regression was used to assess the risk factors.
Results 3470 patients (median age 77 years, IQR 65–85) were enrolled. Pneumococcal pneumonia was identified in 476 (18.3%, n=2605) patients. Multiple serotypes were detected in 42% of them. Risk of having multiple serotypes was low among patients who had received 23-valent pneumococcal polysaccharide vaccine (PPSV23) vaccines (adjusted OR 0.51 (95% CI 0.27 to 0.94)). Proportion of non-PCV7 PPSV23 serotypes in overall distribution of multiple serotypes was 67.4% (n=324/481) compared with 46.4% (n=128/276) in that of single serotypes (p=0.001). Serotypes 5, 9N/9L, 10A, 12/22/46, 17F and 35F were associated with multiple-serotype pneumonia, and serotypes 6A/6B, 23F, 11 and 6C/6D were associated with single-serotype pneumonia. Proportion of more invasive serotypes (serotypes 1, 5, 7F, 8) was significantly higher in multiple-serotype pneumonia (p=0.001).
Conclusions Multiple serotypes of pneumococci are common in sputum of adult patients with pneumonia. The risk of multiple-serotype pneumococcal pneumonia is lower than that of single-serotype pneumococcal pneumonia among PPSV23-vaccinated patients.
Trial registration number UMIN000006909.