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Buruli ulcer is the third most common mycobacterial infection worldwide and is mainly diagnosed in tropical regions. Globally, this progressive disease is caused by Mycobacterium ulcerans; however, Mycobacterium ulcerans subsp. shinshuense, an Asian variant, has been exclusively identified in Japan. Because of insufficient clinical cases, the clinical features of M. ulcerans subsp. shinshuense–associated Buruli ulcer remain unclear. A 70-year-old Japanese woman presented with erythema on her left backhand. The skin lesion deteriorated without an apparent etiology of inflammation, and she was referred to our hospital 3 months after disease onset. A biopsy specimen was incubated in 2% Ogawa medium at 30 °C. After 66 days, we detected small yellow-pigmented colonies, suggesting scotochromogens. Matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI Biotyper; Bruker Daltonics, Billerica, MA, USA) indicated that the organism was Mycobacterium pseudoshottsii or Mycobacterium marinum. However, additional PCR testing for the insertion sequence 2404 (IS2404) was positive, suggesting that the pathogen was either M. ulcerans or M. ulcerans subsp. shinshuense. Further examination by 16S rRNA sequencing analysis, focusing on nucleotide positions 492, 1247, 1288, and 1449–1451, we finally identified the organism as M. ulcerans subsp. shinshuense. The patient was successfully treated with 12 weeks of clarithromycin and levofloxacin treatment. Mass spectrometry is the latest microbial diagnostic method; however, it cannot be used to identify M. ulcerans subsp. shinshuense. To accurately detect this enigmatic pathogen and uncover its epidemiology and clinical characteristics in Japan, more accumulation of clinical cases with accurate identification of the causative pathogen is essential.

Amidst the global spread of antimicrobial resistance, New Delhi metallo-beta-lactamase (NDM)-type carbapenemase-producing Enterobacterales (CPE) remain uncommon in Japan, and the detection of such highly drug-resistant organisms is limited to inbound cases. There is little evidence regarding the prevalence of NDM beta-lactamase gene (blaNDM)-harboring CPE in the domestic community, especially in the provincial cities of Japan. Herein, we report the isolation of a blaNDM-1-harboring plasmid in Enterobacter cloacae complex strain isolated from an elderly woman without a history of traveling abroad who had resided in a long-term care facility in Okayama, Japan. The multidrug-resistant blaNDM-harboring CPE isolate was detected in a stool sample of the patient during routine screening at admission. We performed whole-genome sequencing analysis of the isolate using MiSeq (Illumina) and MinION (Oxford Nanopore Technologies) platforms. The isolate was identified as sequence type 171, which has predominantly been reported in the United States and China. The blaNDM-1 gene was encoded on the 46,161 bp IncX3 plasmid, with sequence similarity to plasmids of similar size isolated from individuals in China. Collectively, the genomic data suggest that an imported CPE isolate may have spread among healthy individuals in the regional area of Japan.

Background: Methicillin-resistant Staphylococcus aureus (MRSA) is a leading cause of nosocomial and community infections, and vancomycin (VCM) is widely recommended as a first-line therapeutic drug. Minimum inhibitory concentrations (MICs) of VCM Methods: We collected data from 2013 to 2020 on S. aureus isolated at the clinical microbiology laboratory at Okayama University Hospital, Japan. We calculated the annual proportions of MRSA isolation rates by MIC levels for nosocomial and community samples and estimated annual percentage changes in the antimicrobial use density of the VCM. Results: Of the 1,716 MRSA isolates, no strains showed intermediate or resistant ranges of VCM MIC levels. By 2020, the proportion of MRSA with an MIC of Conclusion: We demonstrated a deteriorating situation of VCM MIC creep among MRSA strains isolated at our university hospital during the national antimicrobial stewardship campaign.

Intravesical Bacillus Calmette-Guérin (BCG) instillation is an established immunotherapy for superficial bladder cancer. Herein, we describe a case of disseminated BCG infection that developed immediately after the first BCG injection. A 76-year-old man diagnosed with non-invasive bladder cancer underwent intravesical BCG instillation; he developed high fever and systemic arthralgia later that night. General examination did not reveal any infectious sources, and a combination therapy of isoniazid, rifabutin, and ethambutol was initiated after collecting his blood, urine, bone marrow, and liver biopsy samples for mycobacterial cultures. Three weeks later, Mycobacterium bovis was detected in the urine and bone marrow samples, and pathological investigation of liver biopsy revealed multiple small epithelial granulomas with focal multinucleated giant cells, leading to a diagnosis of disseminated BCG infection. The patient recovered after long-term antimycobacterial therapy without remarkable sequelae. Most cases of disseminated BCG infection occur after several doses of BCG injections, and its onset reportedly varies among cases, ranging from a few days to several months. The present case was notable as disease onset was observed only a few hours after the first BCG injection. Although rare, development of disseminated BCG infection should be considered as a differential diagnosis in patients at any time after intravesical BCG instillation therapy.

Background: To mitigate the COVID-19 pandemic, many countries have recommended the use of booster vac-cinations. The relationship between the degree of adverse vaccine reactions and elevated antibody titers is of interest; however, no studies have investigated the temporal changes in antibody titers based on repeated measurements after a third dose of the BNT162b2 vaccine. Methods: This prospective longitudinal cohort study was conducted with 62 healthcare workers who received a third dose of the BNT162b2 at Okayama University Hospital, Japan. Venous blood draw and fingertip whole blood test sample collection were conducted at the early (3-13 days) and 1-month time points; only FWT sample collection was conducted at the 2-month time point. Information on adverse reactions within 1 week after vaccination was also obtained. The association between fever of 37.5 degrees C or higher and antibody titers after the third dose of BNT162b2 was examined using a mixed-effects model and Poisson regression with robust variance. Results: A trend toward higher antibody titers in the early period after vaccination was observed in the febrile individuals, but the differences were not significant at 1 and 2 months post-vaccination (the partial regression coefficient for fever was 8094.3 [-1910.2, 18,098.8] at 1 month after vaccination, and 1764.1 [-4133.9, 7662.1] at 2 months after vaccination in the adjusted models). Conclusion: The findings suggest that the presence of fever after the third vaccine does not predict a sustained elevation in serum antibody titers.

TAFRO syndrome is a rare variant of idiopathic multicentric Castleman's disease, for which disseminated non-tuberculous mycobacteria (NTM) infection must be excluded. However, due to the slow and fastidious growth of the organisms, identification of the pathogen is often challenging. We herein describe a case of disseminated Mycobacterium genavence infection, in which manifestations of the patient were confusingly similar to those of TAFRO syndrome. A 69-year-old Japanese man presented with prolonged fever accompanying pain in his back and ribs on the right side. Systemic investigations revealed thrombocytopenia, marked elevation of alkaline phosphatase, anasarca (pleural effusion and ascites), megakaryocytosis in the bone marrow, and hepatomegaly. Magnetic resonance imaging (MRI) showed diffuse, T1-and T2-low-intensity spotted lesions on his vertebral bodies, but biopsy showed inconclusive results. The patient met the diagnostic criteria of TAFRO syndrome and was started on prednisolone, which improved his general condition shortly thereafter. Blood culture after 42 days of incubation revealed the presence of Mycobacterium; however, we considered it a contamination at that time because no organisms grew on conventional agars, and the patient was discharged. Ten weeks after the isolation of Mycobacterium, he developed persistent fever and was readmitted. This time, vertebral bone mallow biopsy demonstrated a large amount of mycobacterium, which was later successfully identified as M. genavense by sequencing analysis. Under a final diagnosis of disseminated M. genavense infection, we treated the patient with clarithromycin, rifampicin, and ethambutol. This case highlighted that disseminated NTM infection may follow a similar clinical course as that of TAFRO syndrome.

Introduction Recent studies have corroborated that the co-administration of vancomycin (VCM) and piperacillin/tazobactam (PT) is correlated with an increased incidence of acute kidney injury (AKI). However, evidence directed at the Japanese population is scarce. Therefore, we conducted a retrospective study to compare the occurrence of AKI among Japanese patients who received VCM with PT (VP therapy) and VCM with another β-lactams (VA therapy). Methods The present study, performed at Tsuyama Chuo Hospital between June 2012 and December 2018, included adult patients who received VCM and β-lactam antibiotics for ≥48 h. We defined the primary outcome as the incidence of AKI based on the risk, injury, failure, loss, and end-stage kidney disease criteria. Patients' clinical characteristics and outcomes were reviewed and compared between the two groups with univariate and multivariate logistic regression analyses. Subgroup analysis was conducted by stratifying the patients’ baseline hospital admittance status, as intensive care unit or general wards. Results We analyzed 272 patients (92 V P therapy and 180 VA therapy). Univariate analysis revealed a significant difference in AKI development between VP and VA therapy (25.0% vs 12.2%; p < 0.01). A multivariate analysis demonstrated that VP therapy and VCM initial trough levels ≥15 μg/mL were associated with an incidence of AKI. Patients at general wards, rather than those admitted at an intensive care unit, developed AKI with VP therapy (p = 0.02). Conclusion VP therapy was associated with an increased risk of AKI compared to that with VA therapy among the Japanese population.

Mycobacterium chelonae is a rapidly growing mycobacterium that has the potential to cause refractory infections in humans. Mycobacteremia resulting from the organism is extremely rare, and its clinical features are yet to be uncovered. We herein present a case of M. chelonae bloodstream infection involving an immunocompromised older patient. A 79-year-old woman, on a long-term treatment with prednisolone plus tacrolimus for rheumatoid arthritis, visited our outpatient department complaining of deteriorating pain and swelling at her right 1st toe. Laboratory parameters showed elevated C-reactive protein and leukocytosis, and magnetic resonance imaging indicated osteomyelitis at the proximal phalanx of her right 1st toe. Considering the refractory course, the infected toe was immediately amputated. M. chelonae was isolated from bacterial cultures of the resected tissue and blood (BD BACTEC™ FX blood culture system, Becton Dickinson, Sparks, MD, USA), leading to a diagnosis of disseminated M. chelonae infection. We treated the patient with an antibiotic combination of clarithromycin, minocycline, and imipenem (2 weeks), which was converted to oral therapy of clarithromycin, doxycycline, and levofloxacin. This case highlighted the potential pathogenesis of M. chelonae to cause mycobacteremia in an immunocompromised patient.

Appropriate antibiotic prescriptions for outpatients with acute respiratory tract infections (ARTIs) are urgently needed in Japan. However, the empirical proof of this need is under-documented. Therefore, we aimed to determine antibiotic prescription rates, and the proportions of antibiotic classes prescribed for Japanese patients with ARTIs.We analysed health insurance claims data over 2013-2015 among Japanese patients aged75 years and determined the following indicators: 1) visit rates for patients with ARTIs and antibiotic prescription rates per 1000 person-years, and 2) proportion of visits by antibiotic-prescribed patients with ARTIs. We defined broad-spectrum antibiotics using the WHO Anatomical Therapeutic Chemical classification 4 level codes.Among 8.65 million visits due to ARTIs at 6859 hospitals and 62,024 physicians' offices, the visit rate and antibiotic prescription rate per 1000 person-years were 990.6 (99% confidence interval [CI], 989.4-991.7) and 532.4 (99% CI, 531.6-533.3), respectively. The visit rates for patients aged 0-17, 18-59, and 60-74 years were 2410.0 (99% CI, 2407.2-2412.9), 683.6 (99% CI, 682.7-684.6), and 682.1 (99% CI, 678.2-686.0), and antibiotic prescription rates were 1093.3 (99% CI, 1091.4-1095.2), 434.1 (99% CI, 433.4-434.9), and 353.4 (99% CI, 350.7-356.1), respectively. The overall proportion of antibiotic prescriptions for ARTI visits was 52.7% and 91.3% of the antibiotics prescribed were broad-spectrum.Both the visit rates and antibiotic prescription rates for ARTIs were high in this Japanese cohort. The proportion of antibiotic prescriptions exceeded that recommended in the clinical guidelines. Thus, there might be a scope for reducing the current antibiotic prescription rate in Japan.

Mycobacterium kansasii is one of the major non-tuberculous mycobacteria species that typically cause pulmonary diseases. M. kansasii is known to cause septic arthritis as an extrapulmonary disease in immunosuppressed patients or chronic skin disease. Herein, we present a case of M. kansasii arthritis involving the elbow of an immunocompetent patient, which was initially suspected to be a soft-tissue tumor. A 70-year-old man presented with a swollen left elbow that had progressed for 18 months with deteriorating arthralgia and limited range of motion. Magnetic resonance imaging revealed filling of the intra-articular space of the elbow and surrounding of the radial head with a soft tissue mass with mixed signal intensity. Initial incisional biopsy was performed via the lateral approach to the elbow joint, and pathological examination of the mass did not reveal any evidence of malignancy. One year after the first operation, arthroscopic surgery was performed to excise the mass following the recurrence of swelling and limited function of the elbow. Pathological examination of the resected synovium revealed epithelioid granulomas containing a multinucleated giant cell and inflammatory cell infiltration, characteristic of mycobacterial infection. M. kansasii was cultured after 2 weeks of incubation of the synovial sample. He experienced full resolution of the swelling and limited function following a combination of synovectomy and multidrug antimycobacterial treatment (rifampin 600 mg/day, clarithromycin 800 mg/day, and ethambutol 750 mg/day). This case highlights the need to consider this rare infection in the differential diagnosis of intra-articular soft tissue tumor-like lesions even in immunocompetent patients.

Exophiala dermatitidis is a dematiaceous fungus that is increasingly becoming the cause of fungal infection in immunocompromised patients. However, the risk factors and optimal treatment modality for E. dermatitidis infection are unknown to date. Herein, we present a fatal case of E. dermatitidis infection in an adult patient that developed after allogeneic hematopoietic stem cell transplantation for chronic active Epstein-Barr virus infection. The dematiaceous fungus caused a breakthrough fungemia despite prophylactic administration of micafungin. Although the patient was intensively treated with liposomal-amphotericin B and voriconazole, serum level of beta-D-glucan continuously increased, and the patient eventually died because of cerebral hemorrhage. An autopsy found multiple involvements of the fungal infection at the bilateral lungs, thoracic cavities, diaphragm, and thyroid. To the best of our knowledge, this is the first reported case of E. dermatitidis infection involving these tissues as determined via autopsy. This case highlights the importance of attention for Exophiala infection in immunocompromised individuals in those given antifungal therapy with echinocandins.

Healthcare workers (HCWs) are at an increased risk of being exposed to epidemic viral diseases (EVDs), such as measles, rubella, mumps, and varicella-zoster. Currently, in case of the absence of written records on previous immunizations, the Japanese Society for Infection Prevention and Control guidelines require HCWs to have antibody titers higher than laboratory thresholds, possibly leading to over-immunization. We report our vaccination strategy and the consequent incidences of EVDs at the Osaka University Hospital between 2000 and 2016. In 2001, we initiated an annual serology check of antibody titers against EVDs and immunization for newly employed HCWs. As an additional vaccination program, all HCWs with low antibody titers were vaccinated in 2005 and 2010. Antibody titers were determined by an enzyme immunoassay (EIA), with a positive range of >2.0 cut-off index. After implementing the vaccination strategy to keep the laboratory threshold, there were only sporadic cases of EVDs among HCWs. More than 99% of individuals who had positive titers in 2005 remained the positive antibody titers in 2010, indicating that a minimum interval of 5 years is enough to measure immunity. Unprotected workers can, even silently, transmit the contagious viruses to patients and coworkers, possibly resulting in a nosocomial outbreak. However, over-vaccination may yield adverse effects and financial burdens. Our observational data indicate that the laboratory cut-off index of >2.0 by EIA may provide a sufficient herd immunity to prevent EVDs among HCWs.

The gold standard for the diagnosis of coronavirus disease 2019 (COVID-19) is a nucleic acid detection test for severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), which may occasionally reveal false-positive or false-negative results. Herein, we describe a case of a patient infected with human coronavirus NL63 (HCoV-NL63) who was falsely diagnosed with COVID-19 using the Ampdirect™ 2019-nCoV detection kit (Shimadzu Corporation, Japan) and SARS-CoV-2 Detection Kit (TOYOBO co., ltd.), and was admitted to a COVID-19 hospital ward. We suspected a cross-reaction between HCoV-NL63 and SARS-CoV-2; however, the reported genome sequences of HCoV-NL63 and N1/N2 primers for SARS-CoV-2 do not correspond. Thus, the PCR result was supposed to be a false positive possibly due to contamination or human error. Although the issue of a false-negative result has been the focus of much attention to prevent the spread of the disease, a false positive is fraught with problems as well. Physicians should recognize that unnecessary isolation violates human rights and a careful diagnosis is indispensable when the results of laboratory testing for COVID-19 are unclear. Generally, in cases such as a duplicate PCR test was partially positive, either N1 or N2 alone was positive, PCR testing for two or more target regions resulted in a positive only for single region, a high cycle threshold >35 was obtained, a false positive should be suspected. Especially, when these conditions coincide, we should recognize the high likelihood of a false positive.

The number of patients infected with extended-spectrum beta-lactamase (ESBL)-producing organisms has increased dramatically worldwide, and high mortality rates are seen in severely ill patients. This study retrospectively compared the clinical characteristics and outcomes of critically ill patients in an intensive care unit (ICU) at the Tsuyama Chuo Hospital (Okayama, Japan) who were hospitalized for bacteremia caused by ESBL-producing Escherichia coli (ESBL-EC) or non-ESBL-producing E. coli (non-ESBL-EC) between January 2006 and December 2016 (11 years). We analyzed the patients' age, sex, underlying disease(s), sequential organ failure assessment scores, primary focus of bacteremia, empiric antibiotics, rate of appropriateness of empiric antibiotics, and treatment duration, with 28-day mortality being the primary outcome. The study included 24 patients with ESBL-EC bacteremia and 77 with non-ESBL-EC bacteremia. The rate of appropriate initial antibiotic treatment was significantly lower (54.2% vs. 96.1%, respectively; P 0.01) and the mortality due to bacteremia significantly higher (37.5% vs. 15.6%, respectively; P = 0.04) in the ESBL-EC than in the non-ESBL-EC bacteremia group. A subgroup analysis focusing on patients who were administered appropriate empiric antibiotics showed that the 28-day mortality rate did not differ significantly between the two groups (P = 0.23). To our knowledge, this is the first study to compare the outcomes of patients with ESBL-EC and non-ESBL-EC bacteremia in a Japanese ICU setting. Initial empiric antibiotic therapy covering ESBL-producing pathogens should be considered for critically ill patients in the ICU.

The prevalence of carbapenem-resistant Enterobacteriaceae (CRE) has been increasing at medical institutions in Japan without even noticing. Recently, we performed a point prevalence survey for CRE carriage at a medical facility in northern Osaka that demonstrated an unexpectedly high prevalence of blaIMP-6-positive CRE, particularly at long-term care hospitals (LTCH). To identify the risk factors for CRE carriage, we collected clinical data of patients at a representative LTCH. Of 140 patients who were included in this study, 27 (19.3%) were colonized with metallo-beta-lactamase (IMP-6) producers. Pulsed-field gel electrophoresis of the IMP-6 producing Enterobacteriaceae suggested a non-clonal transmission of Escherichia coli, while a clonal spread was shown for Klebsiella pneumoniae. Risk factors for CRE colonization were a longer stay at the hospital stay and a lower independence state, as measured by Norton scales. We propose that a paradigm shift in infection control, inciting a coordinated regional effort to involve LTCHs, should be discussed in the aging society of Japan.

Corynebacterium striatum, generally considered an opportunistic organism in humans, has recently been known to develop high-level daptomycin resistance (HLDR) shortly after drug exposure. To date, however, only several such clinical isolates have been described in the literature and clinical background of the resistant pathogen remains to be elucidated. Here, we report a case involving a C. striatum strain with HLDR harboring novel nucleotide mutations, together with a review of the relevant literature. To the best of our knowledge, this is the first well-investigated clinical report from Japan including a genetic investigation. Considering the rapid emergence of HLDR C. striatum in vitro experiment, there could be a number of underreporting cases. Scrupulous attention is required when administering daptomycin for the treatment of C. striatum infections, even if the organism has initially exhibited susceptibility.

Pasteurella multocida, a zoonotic pathogen in humans, is known to be associated with skin and soft tissue infections following animal bites, but rarely causes visceral infections. We report a case of P. multocida-associated multiple intrapelvic abscesses in a young woman with uterine cervical cancer. A 29-year-old unmarried woman was referred to us because of prolonged high fever accompanying abdominal pain with muscular guarding. She had a domestic cat but denied of any bites or scratches before that. Computed tomography demonstrated ascites and multiple abscesses around her uterus. Her condition did not improve with an initial treatment with flomoxef, clindamycin, and azithromycin. Further, we performed percutaneous pus drainage and switched the antimicrobial therapy to a combination of piperacillin/tazobactam and minocycline for 10 days. Although P. multocida was isolated from vaginal culture, no organisms were isolated from the pus culture. However, further investigation with specimen-direct 16S rDNA analysis diagnosed P. multocida as possibly a single pathogen responsible for the intrapelvic infection. After taking oral levofloxacin for two weeks, no recurrence was reported. Although P. multocida is known as an animal-related pathogen, it can transmit to humans without apparent bites or scratches. The present case illustrates that P. multocida can cause intrapelvic abscess as a result of ascending genital infection.

Propionibacterium acnes is increasingly known as a causative organism for post-neurosurgical infection; however, no clinical studies have examined the risk factors associated with P. acnes infections. Clinical data obtained from 14 cases of P. acnes infection and 28 controls infected with other pathogens were analyzed. Craniotomy, malignancy, and prolonged duration of operation were significantly associated with the onset of P. acnes infection. No fatal cases were reported.

Chromobacterium violaceum is sensitive to temperature and the infection is usually confined to tropical or subtropical regions. Since Japan has a warm climate, C. violaceum has been scarcely isolated from clinical specimens. With global warming, however, the geographical distribution of C. violaceum infection is likely to change. We report two cases of C. violaceum nosocomial pneumonia that occurred at an intensive care center in Japan. C. violaceum was first detected from a patient in the same center as a pathogenic organism of pneumonia. Later, the organism was isolated from sputum and a ventilator circuit tube of another patient in the center. The two patients were admitted to the center in nearby beds for several days. All of the pathogens were confirmed to be C. violaceum by the nucleic acid sequence of the 16S rRNA gene and were proven to be genetically identical organisms by pulsed field gel electrophoresis. Both patients were managed with well-humidified and heated oxygen using a venturi mask and ventilator to promote excretion of sputum. It was thought that the medical respiratory care devices that provide a humid and warm environment, an optimal condition for proliferation of C. violaceum, can contribute to C. violaceum infection in a hospital environment.

A 46-year-old woman was transferred to our emergency unit because of impaired consciousness and respiratory failure with the history of excessive pesticide intake. The patient was hypersalivative and had bilateral pupillary miosis. Laboratory results showed markedly decreased cholinesterase. She was intubated and treated in the intensive care unit with the diagnosis of organophosphorus poisoning. The patient had persisted diarrhea, with a high fever and stomach tenderness on day 10. Whole-body contrast enhanced computed tomography revealed a swollen, enhanced small intestinal wall, and blood culture identified Delftia acidovorans. She was diagnosed as D. acidovorans bacteremia, probably caused by bacterial translocation based on the clinical presentation and the exclusion of other sources, and treated well with a total of 8 days of antibiotic therapy. So far as we know, this is the first case of D. acidovorans bacteremia that was presumably caused by bacterial translocation after organophosphorus poisoning in an immunocompetent adult patient.