Fatal Renal Abscess Caused by Porphyromonas gingivalis and Subcapsular Hemorrhage, Japan.

A 61-year-old man in Japan with abdominal pain was suspected of having a renal tumor. Despite initial treatment, his condition rapidly deteriorated, leading to death. Postmortem examination revealed a renal abscess and sepsis caused by Porphyromonas gingivalis. This case underscores the need to consider atypical pathogens in renal masses.

SARS-CoV-2 co-detection with other respiratory pathogens-descriptive epidemiological study.

BACKGROUND: Co-detection of respiratory pathogens with severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) is poorly understood. This descriptive epidemiological study aimed to determine the effect of the interaction of different respiratory pathogens on clinical variables. METHODS: We retrospectively reviewed the results of comprehensive multiplex polymerase chain reaction (PCR) testing from November 2020 to March 2023 to estimate respiratory pathogen co-detection rates in Shinjuku, Tokyo. We evaluated the interactions of respiratory pathogens, particularly SARS-CoV-2, between observed and expected co-detection. We estimated the trend of co-detection with SARS-CoV-2 in terms of age and sex and applied a multiple logistic regression model adjusted for age, testing period, and sex to identify influencing factors between co-detection and single detection for each pathogen. RESULTS: Among 57,746 patients who underwent multiplex PCR testing, 10,516 (18.2%) had positive for at least one of the 22 pathogens. Additionally, 881 (1.5%) patients were confirmed to have a co-detection. SARS-CoV-2 exhibited negative interactions with adenovirus, coronavirus, human metapneumovirus, parainfluenza virus, respiratory syncytial virus, and rhino/enterovirus. SARS-CoV-2 co-detection with other pathogens occurred most frequently in patients of the youngest age group (0-4 years). A multiple logistic regression model indicated that younger age was the most influential factor for SARS-CoV-2 co-detection with other respiratory pathogens. CONCLUSION: The study highlights the prevalence of SARS-CoV-2 co-detection with other respiratory pathogens in younger age groups, necessitating further exploration of the clinical implications and severity of SARS-CoV-2 co-detection.

Correction: Furugaito et al. Antimicrobial Susceptibility to 27 Drugs and the Molecular Mechanisms of Macrolide, Tetracycline, and Quinolone Resistance in Gemella sp. Antibiotics 2023, 12, 1538.

The authors wish to make the following corrections to this paper [...].

Pneumococcal infectious aortic aneurysm: A caution for a life-threatening vascular complication caused by non-vaccine-covered serotypes.

The 23-valent pneumococcal polysaccharide vaccine (PPSV23) has contributed to reducing pneumonia caused by Streptococcus pneumoniae. However, in Japan, invasive pneumococcal diseases caused by non-vaccine-covered serotypes have increased over the years. A 73-year-old man with a history of PPSV23 was referred to our hospital due to persistent fever and back pain following pneumococcal pneumonia. Contrast-enhanced computed tomography revealed an infectious aneurysm (IAA) at the distal part of the aortic arch. The patient was surgically treated with in situ aortic reconstruction and administered antibiotics. On pathogenic examination of the resected IAA, atherosclerotic changed aortic wall, neutrophil infiltration, and abscesses were observed. Although multiple blood culture tests were negative, tissue culture tests and 16S ribosomal RNA gene-based polymerase chain reaction identified S. pneumoniae. According to capsular polysaccharide synthesis B gene-based serotyping, the serotype was identified as 23A, which is not covered with PPSV23. Serotype 23 is among the most frequently identified serotypes in recent years and associated with in-hospital mortality. Although several pneumococcal serotypes are responsible for lethal infections, the association between these serotypes and disease is uncertain. Further studies on the association between pneumococcal serotypes and IAA, and the development of a broader-covered vaccine are required. Learning objective: •To be able to make a differential diagnosis of invasive pneumococcal pneumonia in patients with persistent fever and newly emerging back pain following pneumococcal infection.•To understand the importance of combining culture tests and molecular analysis to diagnose invasive pneumococcal diseases accurately.•To understand the threat of non-vaccine-covered serotypes even in patients with vaccination histories because the vaccine is limited to only one-fourth of all pneumococcal serotypes.

An Experimental Study on the Addition of Bacteria to Residual Anticancer Drugs: Evaluation of the Effect on Bacterial Growth.

Using anticancer drugs as examples, we examined the possibility of reusing residual drugs. The use of residual drugs is not widespread owing to concerns regarding bacterial contamination. We combined anticancer drugs and bacteria to investigate their effects on bacterial growth. The anticancer drugs carboplatin, paclitaxel, etoposide, irinotecan, methotrexate, and 5-fluorouracil (5-FU) were mixed with Staphylococcus aureus, Enterococcus faecalis, Serratia marcescens, and Escherichia coli. After a certain period, the bacteria were counted. Irinotecan showed no antibacterial activity, whereas 5-FU exhibited high antibacterial activity against the tested bacteria. The 5-FU also showed a minimum inhibitory concentration value in the range of 8-80 µg/mL, depending on the bacterial species. 5-FU dose-dependently inhibited S. aureus growth at more than 0.8 µg/mL. Because protein synthesis systems are reportedly antibiotic targets, we used a cell-free protein synthesis system to confirm the mechanism of the antibacterial activity of the anticancer agent. 5-FU and methotrexate had direct inhibitory effects on protein synthesis. It has been suggested that even if residual drugs are contaminated with bacteria, there will be no microbial growth, or the microbes will be killed by the drug. With careful monitoring, 5-FU can potentially be used for antimicrobial purposes.

Association of Geriatric Nutritional Risk Index With Adverse Event and Treatment Duration in Adjuvant Chemotherapy for Patients With Colorectal Cancer.

BACKGROUND/AIM: In recent years, the Geriatric Nutritional Risk Index (GNRI) has been reported as a predictor of prognosis in many patients with cancer. This study investigated the association of preoperative GNRI with the occurrence of adverse events and duration of treatment with capecitabine plus oxaliplatin (CAPOX), a postoperative adjuvant chemotherapy, in 59 patients with colorectal cancer from September 2019 to April 2022. PATIENTS AND METHODS: A cut-off value of 100.9 was used to categorize patients into high and low GNRI groups. RESULTS: The incidence of grade ≥2 leukopenia (p=0.03), and all grades peripheral neuropathy (p=0.04) were significantly more frequent in the low GNRI group. Analysis of factors influencing treatment duration by univariate and multivariate Cox regression proportional hazards models showed a significant difference in GNRI (p=0.0097). CONCLUSION: GNRI, a nutritional indicator assessed before the start of treatment, influences the occurrence of adverse events and duration of treatment with CAPOX as adjuvant chemotherapy. To complete CAPOX therapy, preoperatively, it is important to assess the patients' nutritional status using the GNRI and to actively intervene in nutritional therapy.

Ralstonia mannitolilytica Bacteremia Stemming From Frequent Outpatient Intravenous Injections at a Local Clinic.

An 83-year-old, male patient was admitted with primary bacteremia caused by Ralstonia mannitolilytica. Before onset, he had been receiving regular injections at a local clinic for abnormal liver function. The present case is the first in which regular injections apparently served as the transmission route for R. mannitolilytica causing bacteremia and demonstrates that this disease can occur in clinics as well as hospitals, raising concerns about the hitherto unnoticed risk of excessive or inappropriate treatments at local clinics.

Secondary spontaneous pneumothorax in a patient with resistant Mycobacterium abscessus infection and systemic sclerosis-associated interstitial lung disease: A case report.

Mycobacterium abscessus subsp. abscessus (MABA) is refractory and sometimes fatal especially in an immunocompromised patient. Also, MABA-associated pneumothorax is an extremely rare complication. We report a case of MABA pulmonary infection complicated pneumothorax treated successfully. A 69-year-old Japanese female with immunosuppressed systemic sclerosis-associated interstitial lung disease experienced left-sided secondary spontaneous pneumothorax. MABA was detected in the pleural effusion and blood culture. Microbial sensitivity test showed the MABA was sensitive to only amikacin, sitafloxacin, and clofazimine. Combination therapy with these antibiotics including azithromycin achieved remission within three weeks. In the treatment of MABA infection, compliance with microbial sensitivity test is crucial.

Antimicrobial Susceptibility to 27 Drugs and the Molecular Mechanisms of Macrolide, Tetracycline, and Quinolone Resistance in Gemella sp.

Gemella is a catalase-negative, facultative anaerobic, Gram-positive coccus that is commensal in humans but can become opportunistic and cause severe infectious diseases, such as infective endocarditis. Few studies have tested the antimicrobial susceptibility of Gemella. We tested its antimicrobial susceptibility to 27 drugs and defined the resistant genes using PCR in 58 Gemella strains, including 52 clinical isolates and six type strains. The type strains and clinical isolates included 22 G. morbillorum, 18 G. haemolysans (GH) group (genetically indistinguishable from G. haemolysans and G. parahaemolysans), 13 G. taiwanensis, three G. sanguinis, and two G. bergeri. No strain was resistant to beta-lactams and vancomycin. In total, 6/22 (27.3%) G. morbillorum strains were erythromycin- and clindamycin-resistant ermB-positive, whereas 4/18 (22.2%) in the GH group, 7/13 (53.8%) G. taiwanensis, and 1/3 (33.3%) of the G. sanguinis strains were erythromycin-non-susceptible mefE- or mefA-positive and clindamycin-susceptible. The MIC90 of minocycline and the ratios of tetM-positive strains varied across the different species-G. morbillorum: 2 µg/mL and 27.3% (6/22); GH group: 8 µg/mL and 27.8% (5/18); G. taiwanensis: 8 µg/mL and 46.2% (6/13), respectively. Levofloxacin resistance was significantly higher in G. taiwanensis (9/13 69.2%) than in G. morbillorum (2/22 9.1%). Levofloxacin resistance was associated with a substitution at serine 83 for leucine, phenylalanine, or tyrosine in GyrA. The mechanisms of resistance to erythromycin and clindamycin differed across Gemella species. In addition, the rate of susceptibility to levofloxacin differed across Gemella sp., and the quinolone resistance mechanism was caused by mutations in GyrA alone.

Siderophore-producing Pantoea ferrattrahens sp. nov. isolated from a clinical specimen and Pantoea ferramans sp. nov. isolated from soil at the bottom of a pond.

Two Gram-negative facultative anaerobes were isolated from a sepsis patient with pancreatic cancer (strain PAGU 2156T ) and soil at the bottom of a pond (strain PAGU 2198T ), respectively. These two strains formed haloes around the colonies on chrome azurol S agar plates, indicating the production of siderophores. Two isolates assigned to the genus Pantoea based on the 16S rRNA gene were differentiated from established species by using polymorphic taxonomies. Phylogenetic analysis using four housekeeping genes (gyrB, rpoB, atpD, and infB) showed that strain PAGU 2156T is closely related to Pantoea cypripedii LMG 2657T (89.9%) or Pantoea septica LMG 5345T (95.7%). Meanwhile, strain PAGU 2198T formed a single clade with Pantoea rodasii DSM 26611T (93.6%) and Pantoea rwandensis DSM 105076T (93.3%). The average nucleotide identity values obtained from the draft genome assembly showed ≤90.2% between strain PAGU 2156T and closely related species and ≤81.5% between strain PAGU 2198T and closely related species. Based on various phenotypes, biochemical properties, and whole-cell fatty acid composition compared with related species, it was concluded that each strain should be classified as a new species of the genus Pantoea. In this manuscript, Pantoea ferrattrahens sp. nov. and Pantoea ferramans sp. nov. with strain PAGU 2156T (=NBRC 115930T = CCUG 76757T ) and strain PAGU 2198T (=NBRC 114265T = CCUG 75151T ) are proposed as each type strain.

[Association of Geriatric Nutritional Risk Index with Adverse Events and Time to Treatment Failure in Malignant Lymphoma Patients Treated with(R-)EPOCH].

To date, there are no reports that examine the relationship between geriatric nutritional risk index(GNRI)at the start of chemotherapy for malignant lymphoma and adverse effects. In this study, we investigated the relationship between GNRI at the start of chemotherapy and the incidence of side effects and time to treatment failure(TTF)in(R-)EPOCH-treated patients with relapsed or refractory malignant lymphoma. A significant difference in the incidence of Grade 3 or higher thrombocytopenia was observed between high and low GNRI groups(p=0.043). The GNRI may be an indicator of hematologic toxicity in malignant lymphoma patients treated with(R-)EPOCH. There was a statistically significant difference in TTF between the high and low GNRI groups(p=0.025), suggesting that nutritional status at the start of(R-)EPOCH may affect treatment continuation.

Influence of Geriatric Nutritional Risk Index on Occurrence of Adverse Events and Duration of Treatment in Patients With Lymphoma Receiving R-CHOP Therapy.

BACKGROUND/AIM: No studies have examined the association between the Geriatric Nutritional Risk Index (GNRI) at the initiation of chemotherapy for malignant lymphoma and the occurrence of adverse events. Therefore, we investigated the impact of GNRI at treatment initiation on the occurrence of side effects and time to treatment failure (TTF) in patients with malignant lymphoma undergoing initial rituximab plus cyclophosphamide, doxorubicin, vincristine, and prednisone (R-CHOP) therapy. PATIENTS AND METHODS: This study included 131 patients who underwent initial R-CHOP therapy between March 2016 and October 2021. Patients were stratified into those with high (GNRI ≥92; n=56) or low (GNRI <92; n=75) GNRI status. RESULTS: Comparing the High GNRI group and Low GNRI group, the incidence of febrile neutropenia (FN) and Grade ≥3 creatinine increase, alkaline phosphatase (ALP) increase, albumin decrease, hemoglobin decrease, neutropenia, and thrombocytopenia were significantly higher in the Low GNRI group. TTF in the High GNRI group was significantly longer than that in the Low GNRI group (p=0.045). Multivariate analysis showed that the factors influencing the duration of treatment were PS (≥2) at the start of treatment, serum albumin level, and GNRI. CONCLUSION: In patients undergoing R-CHOP therapy, GNRI <92 at regimen initiation increased the risks of developing FN and hematologic toxicity. Multivariate analysis revealed that performance status, albumin levels, and GNRI at regimen initiation were the factors influencing treatment duration. Nutritional status at treatment initiation may influence the development of hematologic toxicity and TTF.

In ovo chorioallantoic membrane assay as a xenograft model for pediatric rhabdomyosarcoma.

Rhabdomyosarcoma (RMS) is the most common highly malignant pediatric soft tissue sarcoma. While recent multidisciplinary treatments have improved the 5­year survival rate of low/intermediate­risk patients to 70­90%, there are various complications that arise due to treatment­related toxicities. Immunodeficient mice­derived xenograft models have been widely used in cancer drug research; however, these models have some limitations, including i) they are time­consuming and expensive, ii) their use needs to be approved by animal experimental ethics committees, and iii) the inability to visualize where tumor cells or tissues were engrafted. The present study performed a chorioallantoic membrane (CAM) assay in fertilized chicken eggs, which is time­saving, simple, and easy to standardize and handle because of the high vascularization and the immature immune system of the fertilized eggs. The present study aimed to examine the usability of the CAM assay as a novel therapeutic model for the development of precision medicine for pediatric cancer. A protocol was developed for constructing cell line­derived xenograft (CDX) models using a CAM assay by transplanting RMS cells on the CAM. It was then examined as to whether these CDX models could be used as therapeutic drug evaluation models using vincristine (VCR) and human RMS cell lines. After grafting and culturing the RMS cell suspension on the CAM, three­dimensional proliferation over time was observed visually and by comparing volumes. VCR reduced the size of the RMS tumor on the CAM in a dose­dependent manner. Currently, treatment strategies based on patient­specific oncogenic backgrounds have not been adequately developed in the field of pediatric cancer. The establishment of a CDX model with the CAM assay may lead to the advancement of precision medicine and help formulate novel therapeutic strategies for intractable pediatric cancer.

Validation study of the JSHBPS nomogram for patients with colorectal liver metastases who underwent hepatic resection in the recent era - a nationwide survey in Japan.

BACKGROUND: The Japanese Society of Hepato-Biliary-Pancreatic Surgery (JSHBPS) nomogram was developed to predict disease-free survival in patients with colorectal liver metastases (CRLM) undergoing upfront hepatectomy. However, the utility of the nomogram in patients with resected CRLM remains unknown in the current situation in which treatment strategies are changing with advances in drugs. METHODS: Patients in the initial nomogram cohort (n = 727) and validation cohort (n = 2225) were divided into the upfront hepatectomy and preoperative chemotherapy groups. The nomogram was validated by measuring calibration and discrimination in the two cohorts. Calibration curves were plotted, and survival probabilities were compared. Finally, to quantify the discrimination power, we estimated the concordance index (C-index). RESULTS: In the upfront hepatectomy group, the C-index was 0.63, the suitable cutoff value of the Beppu score was 7, and adjuvant chemotherapy was significantly effective limited to high-risk patients (Beppu score ≥7). The C-index was 0.56 in the preoperative chemotherapy group. CONCLUSIONS: The JSHBPS nomogram remains beneficial for patients undergoing upfront hepatectomy in the recent era but is less effective for patients undergoing hepatectomy after chemotherapy. Patients with a Beppu score ≥7 showed high-risk recurrence, and adjuvant chemotherapy should be recommended for these patients.

The efficacy of neutralizing monoclonal antibodies in transplant recipients with mild-to-moderate COVID-19.

INTRODUCTION: Transplant recipients (TRs) are at high risk for severe coronavirus disease 2019 (COVID-19). Neutralizing monoclonal antibodies (mAbs) are used for treating mild-to-moderate COVID-19. However, reports comparing the efficacy of COVID-19 treatment without/with mAbs in TRs are limited. We assessed the efficacy of casirivimab/imdevimab against mild-to-moderate COVID-19 in TRs. METHODS: Forty-one patients were retrospectively evaluated. The duration until defervescence, oxygen (O2) requirement ≥5 L, and neutralizing antibody levels were compared in TRs with COVID-19 without/with casirivimab/imdevimab. RESULTS: Casirivimab/imdevimab was correlated with shorter duration until defervescence and non-requirement of O2 ≥ 5 L in TRs with COVID-19 [mean: without/with: 6 vs. 2; P = 0.0002, hazard ratio (HR) = 0.3333, 95% confidence interval (CI) = 0.1763-0.6301; 15 vs. 8; P < 0.0001, HR = 0.5333, 95% CI = 0.2878-0.9883; P = 0.0377, HR = 0.1502, 95% CI = 0.02511-0.8980]. Casirivimab/imdevimab was associated with early defervescence after adjusting for sex and age (P = 0.013, HR = 0.412, 95% CI = 0.205-0.826). The antibody levels between patients without/with casirivimab/imdevimab on the day of hospitalization were not significantly different (P = 0.1055), including 13 TRs with vaccination. Antibody levels were higher in patients with casirivimab/imdevimab at 3-5 days after hospitalization than in those without, at 7-9 days after hospitalization (P < 0.0001, mean, without/with: 414.9/40000 AU/mL). CONCLUSION: Casirivimab/imdevimab was effective and increased the neutralizing antibody in TRs with mild-to-moderate COVID-19, it may contribute toward preventing the progression.

Antifungal Stewardship Task Shifting Required of Pharmacists.

Similar to antimicrobial stewardship, the concept of antifungal stewardship (AFS) has also received attention. AFS outcomes include reduced healthcare costs, avoidance of adverse events, and increased implementation of therapeutic drug monitoring (TDM). Several processes and outcome measures have recently been reported for implementing AFS and evaluating its effectiveness in healthcare institutions. This review focuses on our AFS efforts to standardize treatment using a template for pharmacist-led patient intervention for candidemia and to evaluate TDM dosage adequacy rates for voriconazole. The importance of "task shifting", in which the physician's work is transferred or shared with pharmacists and other co-medical staff to alleviate concentration of physician workload, has also been advocated. This review focuses on how pharmacists are involved in AFS.

Association of high cellular expression and plasma concentration of angiopoietin-like 4 with tongue cancer lung metastasis and poor prognosis.

Angiopoietin-like 4 (ANGPTL4) promotes cancer cell migration through vessels and has been implicated in cancer metastasis. Our previous study identified a robust increase in ANGPTL4 mRNA expression in lung-metastasized tongue cancer (TC) cells. Therefore, the present study investigated the association of ANGPTL4 with lung metastasis and outcomes of patient with TC. ANGPTL4 expression in TC cells was investigated by immunohistochemical staining. Patients were classified into 'low (0-30%)' and 'high (>30%)' ANGPTL4-expression groups based on the proportion of ANGPTL4-positive TC cells. The high ANGPTL4-expression group included 15 of 48 patients with TC. Notably, a significantly greater proportion of patients with lung metastasis exhibited a high rate of ANGPTL4-expressing cancer cells compared with patients without lung metastasis (P=0.029). The overall 5-year survival rate was lower in the high (27%) ANGPTL4-expression group compared with the low (68%) ANGPTL4-expression group. Univariate and multivariate analyses revealed that patients with high ANGPTL4 expression in TC cells exhibited significantly lower overall survival (OS) rates [hazard ratio (HR), 2.99; 95% confidence interval (95% CI), 1.34-6.69; P=0.008 and HR, 2.72; 95% CI, 1.14-6.51; P=0.024, respectively]. High plasma ANGPTL4 concentrations as measured by ELISA were associated with lung metastasis (P<0.001). The optimal cut-point for prediction of TC lung metastasis was 9.1 ng/ml (P<0.001; 95% CI, 7.2-10.9). The OS of patients with plasma ANPTL4 above the cut-point was significantly lower than that of patients with plasma ANGPTL4 ≤9.1 ng/ml (P<0.001). These results suggest that a high level of ANGPTL4 in cancer cells and plasma may predict lung metastasis and/or a poor prognosis of patients with TC.

The histone deacetylase inhibitor OBP-801 has in vitro/in vivo anti-neuroblastoma activity.

BACKGROUND: Patients with high-risk neuroblastoma have a poor prognosis; new therapeutic agents are therefore required. We investigated the antitumor effects of OBP-801, a novel histone deacetylase inhibitor, its underlying mechanism, and its potential as a therapeutic agent for patients with neuroblastoma. METHODS: The study included five human neuroblastoma cell lines: IMR32, GOTO, KP-N-RTBM, SK-N-AS, and SH-SY5Y. We investigated cell proliferation, cell cycle status, protein expression patterns, and apoptosis in neuroblastoma cells after OBP-801 treatment in vitro. Cell survival rate and cell cycle were analyzed using the WST-8 assay and flow cytometry, respectively. Apoptosis was detected using annexin V staining, and the expression of apoptosis-related proteins was investigated by western blotting. The antitumor activity of OBP-801 was examined in an in vivo xenograft mouse model. RESULTS: Dose-effect curve analysis showed that the mean half-maximal inhibitory concentration value was 5.5 ± 5.9 nM for the MYCN-amplified cell lines (IMR32, GOTO, and KP-N-RTBM) and 3.1 ± 0.7 nM for the MYCN-nonamplified cell lines (SK-N-AS and SH-SY5Y). OBP-801 inhibited cell proliferation and growth in all the cell lines. It induced G2/M phase arrest through the p21 (CDKN1A) pathway, increasing histone H3 levels and, subsequently, apoptosis in human neuroblastoma cells. OBP-801 suppressed the growth of neuroblastoma cells in the mouse xenograft model. CONCLUSIONS: Overall, OBP-801 induces M-phase arrest and apoptosis in neuroblastoma cells via mitotic catastrophe. Our results indicate that OBP-801 is a promising therapeutic agent with fewer adverse effects for patients with neuroblastoma.

First case of a renal cyst infection caused by Desulfovibrio: a case report and literature review.

BACKGROUND: Genus Desulfovibrio species is a sulphate-reducing anaerobic gram-negative rod that resides in the human oral cavity and intestinal tract. It was reported as the causative pathogen of bacteraemia and abdominal infections, but not renal cyst infection, and Desulfovibrio fairfieldensis has higher pathogenicity than other Desulfovibrio species. CASE PRESENTATION: A 63-year-old man was on haemodialysis for end-stage renal failure due to autosomal dominant polycystic kidney disease. On admission, he had a persistent high-grade fever, right lumbar back pain, and elevated C-reactive protein levels. His blood and urine cultures were negative. He received ciprofloxacin and meropenem; however, there was no clinical improvement. Contrast-enhanced computed tomography and plain magnetic resonance imaging revealed a haemorrhagic cyst at the upper pole of the right kidney. The lesion was drained. Although the drainage fluid culture was negative, D. fairfieldensis was detected in a renal cyst using a polymerase chain reaction. After the renal cyst drainage, he was treated with oral metronidazole and improved without any relapse. CONCLUSIONS: To the best of our knowledge, this is the first reported case of a renal cyst infection with Desulfovibrio species. D. fairfieldensis is difficult to detect, and polymerase chain reaction tests can detect this bacterium and ensure better management for a successful recovery.

Predominance of ST8 and CC1/spa-t1784 methicillin-resistant Staphylococcus aureus isolates in Japan and their genomic characteristics.

OBJECTIVES: Methicillin-resistant Staphylococcus aureus (MRSA) has become a serious epidemiologic problem worldwide. In this study, we aimed to investigate recently isolated MRSA types and determine their characteristics. METHODS: We collected 164 strains isolated from 13 hospitals located in Tokyo and surrounding prefectures. In addition to drug resistance tests, we sequenced whole genomes of the prevalent MRSA clones and analysed their genomic characteristics, such as drug resistance genes, virulence factor genes, and genome arrangements. RESULTS: Multilocus sequencing typing showed that 51% of the SCCmecⅣ MRSA isolates belonged to clonal complex 1 (CC1). Staphylococcus protein A gene (spa) typing showed that 91% of these CC1 isolates could be categorised as t1784 type. These CC1/t1784 isolates possessed genes encoding erythromycin resistance protein, spectinomycin 9-adenylyltransferase, and staphylococcal enterotoxins (SEA, SEI, SEM), but not the pvl gene encoding Panton-Valentine leukocidin. Complete genomic analysis of nine CC1/t1784 isolates showed that they shared an intact phage, which carried no annotated virulence factor genes except for two encoding a hypothetical membrane protein and a teichoic acid biosynthesis protein. No significant genomic rearrangements were observed among the CC1/t1784 isolates. CONCLUSION: These data and previous reports indicate that this CC1/t1784 clone has been expanding rapidly in Japan without genomic changes.