Published papers

Mycolicibacterium litorale is a rapidly growing mycobacterial organism with unknown pathogenic features. Here, we report the complete genome sequence of Mycolicibacterium sp. strain NIID-NTM18, which was isolated from a cardiac implantable electronic device infection and which is most similar to M. litorale This sequence will provide essential information for future studies of the pathogenicity of these mycobacteria.

Background: Nosocomial spread of coronavirus disease 2019 (COVID-19) causes clusters of infection among high-risk individuals. Controlling this spread is critical to reducing COVID-19 morbidity and mortality. We describe an outbreak of COVID-19 in Keio University Hospital, Japan, and its control and propose effective control measures. Methods: When an outbreak was suspected, immediate isolation and thorough polymerase chain reaction (PCR) testing of patients and health care workers (HCWs) using an in-house system, together with extensive contact tracing and social distancing measures, were conducted. Nosocomial infections (NIs) were defined as having an onset or positive test after the fifth day of admission for patients and having high-risk contacts in our hospital for HCWs. We performed descriptive analyses for this outbreak. Results: Between March 24 and April 24, 2020, 27 of 562 tested patients were confirmed positive, of whom 5 (18.5%) were suspected as NIs. For HCWs, 52 of 697 tested positive, and 40 (76.9%) were considered NIs. Among transmissions, 95.5% were suspected of having occurred during the asymptomatic period. Large-scale isolation and testing at the first sign of outbreak terminated NIs. The number of secondary cases directly generated by a single primary case found before March 31 was 1.74, compared with 0 after April 1. Only 4 of 28 primary cases generated definite secondary infection; these were all asymptomatic. Conclusions: Viral shedding from asymptomatic cases played a major role in NIs. PCR screening of asymptomatic individuals helped clarify the pattern of spread. Immediate large-scale isolation, contact tracing, and social distancing measures were essential to containing outbreaks.

A 60-year-old man presented with dyspnea four days after the second dose of the coronavirus disease (COVID-19) vaccine. Imaging revealed extensive ground-glass opacification. Blood tests were notable for elevated KL-6 levels. Bronchoalveolar lavage fluid analysis showed increased lymphocyte-dominant inflammatory cells and decreased CD4/CD8 ratio. These findings were consistent with the diagnosis of drug-induced interstitial lung disease (DIILD). To the best of our knowledge, this has never been reported in previous literature. Treatment with glucocorticoids relieved his symptoms. This paper highlights that although extremely rare, COVID-19 vaccine could cause DIILD, and early diagnosis and treatment are crucial to improve patient outcomes.

INTRODUCTION: In the novel coronavirus disease (COVID-19) pandemic era, it is essential to rule out COVID-19 effectively to prevent transmission in both communities and medical facilities. According to previous reports in high prevalence areas, CT screening may be useful in the diagnosis of COVID-19. However, the value of CT screening in low prevalence areas has scarcely been reported. METHODS: This report examines the diagnostic efficacy of CT screening before admission to a hospital in Tokyo. We conducted a retrospective analysis at Keio University Hospital from April 6, 2020, through May 29, 2020. We set up an outpatient screening clinic on April 6 for COVID-19, administering both PCR with nasopharyngeal swabs and chest CT for all patients scheduled for surgery under general anesthesia. RESULTS: A total of 292 asymptomatic patients were included in this study. There were three PCR-positive patients, and they all had negative CT findings, which revealed that both the sensitivity and positive predictive value of CT (PPV) were 0%. There were nine CT-positive patients; the specificity and the negative predictive value (NPV) were 96.9% and 98.9%, respectively. CONCLUSION: CT screening was not useful in low prevalence areas at this time in Tokyo, even with the inclusion of the most prevalent phase. Given that the utility of CT screening depends on disease prevalence, the criteria for performing CT screening based on the prevalence of COVID-19 should be established.

40代女性。健診の胸部X線で異常陰影を指摘された。胸部X線、胸部CT所見にて右肺尖部の空洞病変と右上肺野の粒状影が認められた。胸部CTで右上葉に空洞病変を認め、周囲に粒状影・浸潤影を伴う限局性の薄い胸膜肥厚を有していた。気管支洗浄液一般細菌培養でコロニーを認めたが少数であったため、菌種同定目的に16SrRNA解析を行った。その結果、Actinomyces odontolyticusで肺放線菌症と診断された。ペニシリン系抗菌薬の静注を行ったところ、浸潤影は縮小し改善傾向となった。

We report herein on a rare case of tetanus originating from ulcerated breast cancer. A 60-year-old homeless woman was admitted to our hospital because of lockjaw. On admission, a physical examination revealed tachypnea, trismus, opisthotonus and an ulcerated right breast. There was no other skin soft tissue damage. A diagnosis of tetanus was entertained from the lockjaw and opisthotonus. Tetanus globulin, tetanus toxoid, penicillin and respiratory support were initiated. Later, a right total mastectomy was performed, and the diagnosis of breast cancer was made, however, gram positive bacilli were not detected and Clostridiuum tetani (C. tetani) was not cultured. It is conceivable that the ulcerated breast was contaminated with C. tetani due to the patients living conditions.

We report herein on a case of Plasmodium malariae malaria with more than a 4-month incubation period. A 35-year-old Japanese man who first presented to our clinic with fever and history of travel to Papua New Guinea was suspected of having Plasmodium vivax malaria based on peripheral smear results. We admitted him and initiated treatment with mefloquine. After two days of therapy, he became afebrile. We discharged him, and P. vivax was later confirmed with PCR. We started mefloquine prophylaxis for a planned trip to Papua New Guinea. After his return, a standard dose of primaquine (15 mg x 14 days) was prescribed for a radical cure of P. vivax. About 4 months after his last visit to Papua New Guinea, he returned to our clinic with fever. We suspected a relapse of P. vivax malaria and admitted him for a second time. After two days of mefloquine therapy, his symptoms improved. We discharged him and restarted a higher dose of primaquine (30 mg x 14 days) therapy for a radical cure of P. vivax. Subsequently, the PCR test revealed the parasite was P. malariae and not P. vivax. Only 13 cases of Plasmodium malariae malaria have been reported in Japan during the past 10 years. Blood-stage schizonticides such as mefloquine is not active against the liver stage. Therefore, the use of these drugs for prophylaxis will not be effective for prevention of malaria if its liver stage is longer than the duration of effective chemoprophylaxis. Although the incubation period of P. malariae is typically 13 to 28 days, it occasionally lasts for months or even years. Careful attention should be given to the possibility that P. malariae occasionally has a long incubation period even in the absence of the hypnozoite stage.

OPAT (Outpatient Parenteral Antimicrobial Therapy) is widely utilized in various countries. Although once-daily parenteral antimicrobials are often prescribed in outpatient clinics, the term "OPAT" is not commonly used, and no well-organized OPAT practice has been reported in Japan. We implemented OPAT with continuous infusion using elastomeric infusion devices, which are commonly used in Australia and Singapore. We collected data about diseases, organisms, antimicrobials, treatment duration, bed days saved, outcome, readmission rate and cost reductions of all patients who were treated with OPAT with continuous infusions from July 2012 till June 2013. Ten patients (5 osteomyelitis, 4 abscess and 1 endocarditis) were treated and only one patient discontinued therapy due to the side effects of the antimicrobial. The most commonly targeted organism was Staphylococcus aureus. Cefazolin was the most frequently prescribed antimicrobial. The median OPAT days were 15 (range 4-29 days). Total bed days saved were 159. A peripherally inserted central catheter (PICC) was inserted for all patients and only one had to change the PICC during the treatment. Eight patients were cured and 2 were improved. No patient needed readmission. The estimated medical cost reduction was 1,655,930 yen, that is approximately 16,000 US dollars. Administration with continuous infusion makes it possible to continue the optimal parenteral antimicrobials for outpatients, which avoids prescribing unnecessary once-daily antimicrobials with a broader spectrum. Our experience shows OPAT with continuous infusion is safe and feasible practice not only for improving the QOL of patients but also for efficient bed utilization and medical cost savings.

INTRODUCTION: Rapid antigen detection (RAD) tests are convenient tools for detecting the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) in clinics, and testing using saliva samples could decrease the risk of infection during sample collection. This study aimed to assess the accuracy of the SARS-CoV-2 RAD for testing of nasopharyngeal swab specimens and saliva samples in comparison with the RT-PCR tests and viral culture for detecting viable virus. METHODS: One hundred seventeen nasopharyngeal swab specimens and 73 saliva samples with positive results on RT-PCR were used. Residual samples were assayed using a commercially available RAD test immediately, and its positivity was determined at various time points during the clinical course. The concordance between 54 nasopharyngeal swab samples and saliva samples that were collected simultaneously was determined. Viral culture was performed on 117 samples and compared with the results of the RAD test. RESULTS: The positive rate of RAD test using saliva samples was low throughout the clinical course. Poor concordance was observed between nasopharyngeal swab specimens and saliva samples (75.9%, kappa coefficient 0.310). However, a substantially high concordance between the RAD test and viral culture was observed in both nasopharyngeal swab specimens (86.8%, kappa coefficient 0.680) and saliva samples (95.1%, kappa coefficient 0.643). CONCLUSIONS: The sensitivity of the SARS-CoV-2 RAD test was insufficient, particularly for saliva samples. However, a substantially high concordance with viral culture suggests its potential utility as an auxiliary test for estimating SARS-CoV-2 viability.

This study investigated, using cycle threshold (Ct) qPCR values, the association between symptoms and viral clearance in 57 patients with asymptomatic/mild SARS-CoV-2 infection. Patients with olfactory/taste disorders (OTDs) exhibited lower qPCR Ct values and longer time to negative qPCR than those without OTDs, suggesting an association between OTDs and high viral burden.