石和田 稔彦

OBJECTIVES: In Japan, population-based epidemiological data on respiratory syncytial virus (RSV) infections are limited. To elucidate the epidemiology of RSV before the introduction of new prophylactic drugs, we conducted a population-based study during and after the SARS-CoV-2 pandemic. METHODS: This study was performed in four hospitals in Chiba City and three hospitals in Ichihara City. Clinical information and residual samples from RSV rapid antigen tests of infants under one year old were collected. Samples from patients with lower respiratory tract infections (LRTI) were analyzed using the FilmArray Respiratory 2.1 panels. RESULTS: A total of 1200 infants underwent the RSV rapid antigen test, with 497 diagnosed with LRTI. Although five samples could not be stored, 252 out of 492 (51.2%) were positive for RSV. Among the RSV PCR-positive infants, 63 (25.0%) had underlying diseases, compared to 100 out of 240 (41.7%) RSV PCR-negative infants (p < 0.05). In Chiba City, the annual incidence of hospitalization per 1000 children was 12.7 in 2021, 4.4 in 2022, and 9.2 in 2023. CONCLUSIONS: During and after the SARS-CoV-2 pandemic, most hospitalized infants with RSV-LRTI did not have underlying diseases. Widespread use of prophylaxis in infants without underlying disease is desirable.

INTRODUCTION: To understand the in-vivo dynamics in pneumococci, investigation into the carriage in patients with invasive pneumococcal disease (IPD) is extremely important. METHODS: To clarify genomic and morphological differences between pneumococcal strains simultaneously isolated from different sites in a patient with IPD, we conducted comparative analyses of two strains. A capsular strain isolated from the blood and a non-capsular strain isolated from the sputum of a patient with IPD were used. RESULTS: The strain isolated from blood was serotype 24B with capsule. The strain isolated from sputum with capsular type 24 genes was non-encapsulated, and genomic analysis revealed an insertion region in the wcxK gene. Its biofilm-forming capacity was higher than that of the capsular strain, as was that of the pspK-positive true non-encapsulated strain. Furthermore, observing the microbe using transmission electron microscopy revealed that the strain isolated from sputum lacked a capsule, like the pspK-positive true non-encapsulated strain. CONCLUSIONS: Our analysis of the two strains isolated from the blood and sputum of a patient with IPD showed one possible in-vivo morphological change in Streptococcus pneumoniae.

急性リンパ芽球性白血病の15歳男子。抗真菌薬の予防投与下でHLA不一致血縁者骨髄移植を施行した。移植片対宿主病を発症しタクロリムス,プレドニゾロンによる免疫抑制の強化を要した。移植後82病日より発熱・咳嗽,SpO2低下と炎症反応上昇を認めた。胸部単純CTで結節影を認めアスペルギルス感染を強く疑った。タクロリムス使用中であり第1選択薬であるボリコナゾールは相互作用のため使用できず,リポ化アムフォテリシンB投与を開始した。その後画像所見上悪化あり,タクロリムスを中止しボリコナゾールへ変更した。アスペルギルス抗原,(1→3)-β-D-グルカン陽性より侵襲性肺アスペルギルス症と診断した。経験的治療を開始し複数の方法により診断に至ったが,併用薬により第1選択薬が使用できず治療に難渋した。移植後の合併症に対する薬剤使用下に好発する感染症においては,早期の診断と治療が重要である。(著者抄録)