Published papers

35歳男。パプアニューギニアから帰国後8日目から約1週間持続する発熱と関節痛を主訴に受診し、三日熱マラリアの診断で入院となった。メフロキン内服にて症状は改善た。退院11日後に再度パプアニューギニアへ渡航した。1週間の滞在後帰国し予防内服は4週間継続した。その後、他院にてプリマキンによる根治治療を14日間施行され無症状で経過していたが、最終渡航から約4ヵ月後に2週間持続する間欠的な発熱、咳嗽を認めたため再受診した。ギムザ染色で赤血球内の輪状体を確認した。複数の輪状体を含む赤血球は存在しなかった。輪状体の寄生している赤血球の膨化は明らかではなかった。寄生率は0.06%と低値であった。再びメフロキン内服を開始したが、前回眩暈の副作用が強かったため、投与量を減量した。治療後すぐに解熱し咳嗽も改善したため退院となった。G6PD(グルコース-6-リン酸脱酵素)欠損がないことを確認し、プリマキンを増量して14日間の根治治療を行った。その後、PCR検査にて4日熱マラリアの単独感染であったことが判明した。

医療従事者におけるCOVID-19の適切な感染対策を検討するため、血清抗体検査の陽性率から感染状況を推測した。さらに、血清抗体陽性者と陰性者の背景や臨床情報を比較し、感染者の特徴や感染危険因子を探索した。本大学医学部と大学病院に所属する医療従事者に対して2020年8月に実施した定期検査の際に、研究参加同意の得られた2341人を対象とした。COVID-19の既往歴のある21人を除外した2320人におけるIgG抗体陽性者は20人(0.862%)であった。年齢や職種では抗体陽性率に有意差はなかったが、性別は男性の方が有意に抗体陽性率が高かった。抗体陽性者は何らかの症状、特に嗅覚障害や味覚障害、発熱があった者で多かった。医療機関におけるCOVID-19の集団感染を防ぐために、医療従事者は適切な標準感染予防策と感染予防経路別予防策を実施し、発熱や嗅覚・味覚障害といった症状が出現した際は速やかに就業を中止すべきであると考えられた。

The reduced vaccine efficacy against the SARS-CoV-2 variant lineage B. 1.351 (beta variant) containing the E484K and N501Y mutations is well known. The E484K mutation in SARS-CoV-2 is thought to be responsible for weakened humoral immunity. Vaccine efficacy against the R.1 lineage, which contains the E484K mutation but not the N501Y mutation, is uncertain. Serum samples were collected from 100 healthy Japanese participants three weeks after receiving the second dose of the BNT162b2 vaccine, and serum neutralization antibody titers were measured against five SARS-CoV-2 variants. The geometric mean neutralization titers measured for the original and R.1 lineages were equivalent (91.90 +/- 2.40 and 102.67 +/- 2. 28, respectively), whereas a low titer was measured for the beta variant (18.03 +/- 1.92). Although further investigations with other variant strains and serum samples are essential, our results imply that the weakened humoral response is not caused solely by the E484K mutation. (UMIN000043340). (c) 2022 Elsevier Ltd. All rights reserved.

The reduced vaccine efficacy against the SARS-CoV-2 variant lineage B. 1.351 (beta variant) containing the E484K and N501Y mutations is well known. The E484K mutation in SARS-CoV-2 is thought to be responsible for weakened humoral immunity. Vaccine efficacy against the R.1 lineage, which contains the E484K mutation but not the N501Y mutation, is uncertain. Serum samples were collected from 100 healthy Japanese participants three weeks after receiving the second dose of the BNT162b2 vaccine, and serum neutralization antibody titers were measured against five SARS-CoV-2 variants. The geometric mean neutralization titers measured for the original and R.1 lineages were equivalent (91.90 ± 2.40 and 102.67 ± 2.28, respectively), whereas a low titer was measured for the beta variant (18.03 ± 1.92). Although further investigations with other variant strains and serum samples are essential, our results imply that the weakened humoral response is not caused solely by the E484K mutation. (UMIN000043340).

The reduced vaccine efficacy against the SARS-CoV-2 variant lineage B. 1.351 (beta variant) containing the E484K and N501Y mutations is well known. The E484K mutation in SARS-CoV-2 is thought to be responsible for weakened humoral immunity. Vaccine efficacy against the R.1 lineage, which contains the E484K mutation but not the N501Y mutation, is uncertain. Serum samples were collected from 100 healthy Japanese participants three weeks after receiving the second dose of the BNT162b2 vaccine, and serum neutralization antibody titers were measured against five SARS-CoV-2 variants. The geometric mean neutralization titers measured for the original and R.1 lineages were equivalent (91.90 ± 2.40 and 102.67 ± 2.28, respectively), whereas a low titer was measured for the beta variant (18.03 ± 1.92). Although further investigations with other variant strains and serum samples are essential, our results imply that the weakened humoral response is not caused solely by the E484K mutation. (UMIN000043340).

BACKGROUND: In multidrug regimens, including an intravenous aminoglycoside (e.g. amikacin [AMK]) is recommended for difficult-to-treat non-tuberculous mycobacterial (NTM) lung diseases. We aimed to evaluate the efficacy, safety, and feasibility of inhaled AMK therapy in patients with difficult-to-treat NTM lung diseases in a retrospective chart review. METHODS: The study population consisted of patients with NTM lung diseases who received combination therapy, including inhaled AMK therapy, at Keio University Hospital (Tokyo, Japan), from January 2014 through May 2016. A total of 26 cases, consisting of 23 Mycobacterium avium complex (MAC) and three Mycobacterium abscessus complex (MABC) infections cases, were included in this study. The efficacy, safety, and feasibility of inhaled AMK therapy were retrospectively investigated. The Research Ethics Committee of Keio University Hospital approved this study, and informed consent was obtained from all patients. RESULTS: All 26 patients were culture-positive at enrolment. Twenty-three of the 26 patients (88.5%), including 21/23 MAC patients (91.3%) and 2/3 MABC patients (66.7%), were administered inhaled AMK therapy for >3 months. The proportion of patients who had clinical symptoms, including, cough and sputum, declined after inhalation AMK therapy. Ten of the 23 patients (43.5%) who received AMK inhalation, including 8/21 MAC (38.1%) and 2/2 MABC patients (100%), showed sputum conversion, defined as at least three consecutive negative sputum cultures. Seven of the 23 patients, including, 5/21 MAC and 2/2 MABC patients, showed improvements in high-resolution computed tomography imaging of the chest. In addition, the serum AMK trough levels before the second inhalation were <1.2 μg/mL in all 26 patients, with no occurrence of severe adverse events, such as renal toxicity. One patient (3.8%) experienced auditory toxicity, in the form of tinnitus. However, this symptom was reversible, after temporary interruption of AMK, the patient was able to safely resume the therapy. CONCLUSIONS: Inhaled AMK therapy is an effective and feasible therapy for difficult-to-treat NTM lung disease.

We herein report a case of acute cholangitis and bacteremia caused by a commensal Neisseria species, Neisseria subflava, in an 82-year-old man with cholangiocarcinoma. Emergency endoscopic nasobiliary drainage and cefoperazone/sulbactam therapy were effective. Gram negative coccobacilli were isolated from both blood and bile cultures on 5% sheep blood agar. The isolate was identified as N.subflava biovar perflava by mass spectrometry, a sequence analysis of the 16S rRNA, and biochemical testing. Although biliary infections due to commensal Neisseria are extremely rare, this case demonstrates the possibility of its occurrence in patients undergoing bile duct treatment.

The clinical course of coronavirus disease 2019 (COVID-19) varies from mild to critical. We retrospectively examined whether clinical and laboratory findings on admission could predict COVID-19 prognosis. Among various factors associated with COVID-19 severity, our results indicated that the real-time reverse transcription-polymerase chain reaction (RT-PCR) threshold cycle (Ct) values for severe acute respiratory syndrome coronavirus 2 were the most useful predictor of COVID-19 prognosis.

Introduction. The incidence of Mycobacterium avium complex (MAC) pulmonary disease (MAC PD), a refractory chronic respiratory tract infection, is increasing worldwide. MAC has three predominant colony morphotypes: smooth opaque (SmO), smooth transparent (SmT) and rough (Rg).Aim. To determine whether colony morphotypes can predict the prognosis of MAC PD, we evaluated the virulence of SmO, SmT and Rg in mice and in human macrophages.Methodology. We compared the characteristics of mice and human macrophages infected with the SmO, SmT, or Rg morphotypes of M. avium subsp. hominissuis 104. C57BL/6 mice and human macrophages derived from peripheral mononuclear cells were used in these experiments.Results. In comparison to SmO- or SmT-infected mice, Rg-infected mice revealed severe pathologically confirmed pneumonia, increased lung weight and increased lung bacterial burden. Rg-infected macrophages revealed significant cytotoxicity, increased bacterial burden, secretion of proinflammatory cytokines (TNF-α and IL-6) and chemokines (CCL5 and CCL3), and formation of cell clusters. Rg formed larger bacterial aggregates than SmO and SmT. Cytotoxicity, bacterial burden and secretion of IL-6, CCL5 and CCL3 were induced strongly by Rg infection, and were decreased by disaggregation of the bacteria.Conclusion.M. avium Rg, which is associated with bacterial aggregation, has the highest virulence among the predominant colony morphotypes.