Satoshi Ichiyama

Kyoto University, Kioto, Kyōto, Japan

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Publications (220)547.67 Total impact

  • [Show abstract] [Hide abstract]
    ABSTRACT: Surveillance of Streptococcus pneumoniae serotypes is important for the successful implementation of vaccination strategies to prevent the spread of invasive pneumococcal diseases. The standard method of serotyping of pneumococcal isolates is the phenotypic Neufeld test, which is cost- and labor-intensive. Recently, matrix-assisted laser desorption ionization-time of flight mass spectrometry (MALDI-TOF MS) has been implemented as a rapid, simple and inexpensive method for identifying species. We evaluated the performance of MALDI-TOF MS for serotyping ten major serotypes of S. pneumoniae in Japan (serotypes 3, 6B, 15A, 15C, 19A, 19 F, 23A, 24 F, 35B and 38) using the Biotyper and ClinProTools. After optimizing the settings, we validated their serotyping performance for serotypes 3, 15A and 19A using a separate set of isolates that were not used in the creation of the classification algorithms. A total of 574 isolates of S. pneumoniae collected from Japanese nationwide surveillance studies were included. Of these, 407 isolates belonged to the ten major serotypes. Biotyper and ClinProTools correctly identified 77.9 % and 84.0 %, respectively, of the ten major serotype isolates. The validation analysis included a total of 113 isolates of the serotypes 3, 15A and 19A isolates. Biotyper and ClinProTools correctly identified 85.0 % and 69.9 % of the validation cohort isolates, respectively. MALDI-TOF MS has the potential to discriminate the ten major S. pneumoniae serotypes prevalent in Japan.
    European Journal of Clinical Microbiology 08/2015; DOI:10.1007/s10096-015-2468-9 · 2.67 Impact Factor
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    ABSTRACT: Intravenous immunoglobulin (IVIG) is periodically administered to immunocompromised patients together with antimicrobial agents. The evidence that supports the effectiveness of IVIG is mostly based on data from randomized clinical trials; the underlying mechanisms are poorly understood. A recent study revealed that killing of multidrug-resistant bacteria and drug-sensitive strains by neutrophils isolated from healthy donors is enhanced by an IVIG preparation. However, the effectiveness of IVIG in immunocompromised patients remains unclear. The present study found that IVIG increased both killing activity and O2(-) release by neutrophils isolated from six patients receiving immune-suppressive drugs after hematopoietic stem cell transplantation (HSCT); these neutrophils killed both multidrug-resistant extended-spectrum β-lactamase-producing Escherichia coli (E. coli) and multidrug-resistant Pseudomonas aeruginosa (P. aeruginosa). Moreover, IVIG increased the autophagy of the neutrophils, which is known to play an important role in innate immunity. These results suggest that IVIG promotes both the killing activity and autophagy of neutrophils isolated from immunocompromised patients against multidrug-resistant bacteria. Copyright © 2015. Published by Elsevier Inc.
    Biochemical and Biophysical Research Communications 06/2015; 464(1). DOI:10.1016/j.bbrc.2015.06.004 · 2.30 Impact Factor
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    ABSTRACT: The efficacy of cefmetazole and flomoxef (CF) for the treatment of patients with extended-spectrum β-lactamase-producing Escherichia coli (ESBL-EC) bacteremia (ESBL-CF group) was compared with carbapenem treatment for ESBL-EC patients (ESBL-carbapenem group) and with the efficacy of CF treatment in patients with non-ESBL-EC bacteremia (non-ESBL-CF group). Adult patients treated for EC bacteremia in four hospitals were retrospectively evaluated. The thirty-day mortality rates in patients belonging to the ESBL-CF, ESBL-carbapenem, and non-ESBL-CF groups were compared as 2 (empirical and definitive therapy) cohorts. The adjusted hazard ratios (aHRs) for mortality were calculated using Cox regression models with weighting according to the inverse probability of propensity scores for receiving CF or carbapenem treatment. The empirical therapy cohort included 104 patients (ESBL-CF, 26; ESBL-carbapenem, 45; non-ESBL-CF, 33), and the definitive therapy cohort included 133 patients (ESBL-CF, 59; ESBL-carbapenem, 54; non-ESBL-CF, 20). The crude 30-day mortality rates for patients in the ESBL-CF, ESBL-carbapenem, and non-ESBL-CF groups were, respectively, 7.7%, 8.9%, and 3.0% in the empirical cohort and 5.1%, 9.3%, and 5.0% in the therapy cohort. In patients without hematological malignancy and neutropenia, CF treatment for ESBL-EC patients was not associated with mortality when compared with carbapenem treatment (empirical therapy cohort, aHR 0.87, 95% confidence interval [CI] 0.11-6.52; definitive therapy cohort, aHR 1.04, CI 0.24-4.49). CF therapy may represent an effective alternative to carbapenem treatment for patients with ESBL-EC bacteremia for empirical and definitive therapy in adult patients who do not have hematological malignancy and neutropenia. Copyright © 2015, American Society for Microbiology. All Rights Reserved.
    Antimicrobial Agents and Chemotherapy 06/2015; 59(9). DOI:10.1128/AAC.00701-15 · 4.48 Impact Factor
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    ABSTRACT: Objectives: The global increase in ESBL-producing Escherichia coli is associated with the ST131 clonal group, especially its CTX-M-15-producing H30Rx subset. To understand the rapid spread of ESBL-producing E. coli in Japan, we investigated the molecular epidemiology and ESBL-associated genetic environments of Japanese ST131 isolates. Methods: Between 2001 and 2012, 1079 ESBL-producing E. coli isolates were collected at 10 Japanese acute-care hospitals. ESBL types, ST131 status, fimH allele, H30Rx-defining sequences and ESBL-associated genetic environments were defined using PCR and sequencing. Subclonal groups were defined based on fimH allele and H30Rx status. Results: Overall, 461 (43%) of the 1079 ESBL-producing E. coli isolates represented ST131. According to fimH-based subclonal typing, the ST131 isolates included 398 fimH allele 30 (H30) isolates, 49 H41 isolates, 10 H22 isolates and 4 other fimH-type isolates. The 398 H30 isolates included 396 ciprofloxacin-resistant H30R isolates, of which 64 (16%) represented the H30Rx subset. Between 2001 and 2007, the CTX-M-14-producing H30R subgroup predominated, accounting for 46% of ST131 isolates, whereas the CTX-M-27-producing H30R and CTX-M-15-producing H30Rx subgroups were rarely detected. In contrast, from 2008 onward the latter two subgroups rose to dominance, accounting for 45% and 24% of ST131 isolates, respectively, versus only 15% for the (formerly dominant) CTX-M-14-producing H30R subgroup. The emergent CTX-M-27-H30R subgroup frequently had an IS26-ΔISEcp1-blaCTX-M-27-ΔIS903D-IS26-like structure, whereas the older CTX-M-14-H30R subgroup frequently had an ISEcp1-blaCTX-M-14-IS903D-like structure. Conclusions: This Japanese regional ESBL-producing E. coli epidemic is closely associated with newly identified CTX-M-27- and CTX-M-14-producing ST131 H30R subclonal groups and with mobile elements IS26, ISEcp1 and IS903D.
    Journal of Antimicrobial Chemotherapy 02/2015; 70(6). DOI:10.1093/jac/dkv017 · 5.31 Impact Factor
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    ABSTRACT: This study was conducted to evaluate trends in the isolation of strains of nontuberculous mycobacteria (NTM) and trends in the number of patients with pulmonary Mycobacterium avium complex (MAC) disease. We retrospectively reviewed microbiological results and clinical data to identify patients who were diagnosed with pulmonary MAC disease at Kyoto University Hospital in Japan between 2000 and 2013. NTM were isolated from 6,327 of 80,285 samples (7.9%) for mycobacterial culture. The proportion of NTM isolates among all mycobacterial isolates increased from 355 of 792 samples (44.8%) in 2000 to 688 of 847 samples (81.2%) in 2013. MAC was most frequently observed (5436 isolates, 85.9%), followed by M. abscessus (175 isolates, 2.8%) and M. kansasii (74 isolates, 1.2%). A total of 592 patients with pulmonary MAC disease were identified (age, 66.0±11.5 years; females, 61.1%). Compared with the early cohort (2000-2006, 236 patients), more patients in the late cohort (2007-2013, 356 patients) had an underlying disease (157 [66.5%] vs. 284 [79.8%], P=0.0003), a Charlson comorbidity index score ≥1 (115 [48.7%] vs. 213 [59.8%], P=0.008), collagen vascular disease (18 [7.6%] vs. 60 [16.9%], P=0.001), rheumatoid arthritis (11 [4.7%] vs. 41 [11.5%], P=0.004), and used immunosuppressive drugs (22 [9.3%] vs. 63 [17.7%], P=0.004). The numbers of patients with lung disease, malignant disease and diabetes mellitus increased; however, their frequencies did not differ. The recovery rate of NTM and patients with pulmonary MAC disease increased, especially in patients with collagen vascular disease or rheumatoid arthritis or who used immunosuppressive drugs.
    Journal of Infection and Chemotherapy 01/2015; 21(5). DOI:10.1016/j.jiac.2015.01.004 · 1.49 Impact Factor
  • Japanese Journal of Environmental Infections 01/2015; 30(3):189-194. DOI:10.4058/jsei.30.189
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    ABSTRACT: Stenotrophomonas maltophilia (SM) is an important nosocomial pathogen that exhibits intrinsic resistance to various antimicrobial agents. However, the risk factors for SM bacteraemia have not been sufficiently evaluated. From January 2005 to September 2012, we retrospectively compared the clinical backgrounds and outcomes of SM bacteraemic patients (SM group) with those of bacteraemic patients due to Pseudomonas aeruginosa (PA group) or Acinetobacter species (AC group). DNA genotyping of the SM isolates using the Diversilab system was performed to investigate the genetic relationships among the isolates. The SM, PA, and AC groups included 54, 167, and 69 patients, respectively. Nine of 17 patients in the SM group receiving trimethoprim-sulfamethoxazole prophylaxis developed SM bacteraemia. Independent risk factors for SM bacteraemia were the use of carbapenems and antipseudomonal cephalosporins and SM isolation within 30 days prior to the onset of bacteraemia. Earlier SM isolation was observed in 32 of 48 patients (66.7%) with SM bacteraemia who underwent clinical microbiological examinations. Of these 32 patients, 15 patients (46.9%) had the same focus of bacteraemia as was found in the previous isolation site. The 30-day all-cause mortality rate among the SM group (33.3%) was higher than that of the PA group (21.5%, p = 0.080) and the AC group (17.3%, p = 0.041). The independent factor that was associated with 30-day mortality was the SOFA score. DNA genotyping of SM isolates and epidemiological data suggested that no outbreak had occurred. SM bacteraemia was associated with high mortality and should be considered in patients with recent use of broad-spectrum antibiotics or in patients with recent isolation of the organism.
    PLoS ONE 11/2014; 9(11):e112208. DOI:10.1371/journal.pone.0112208 · 3.23 Impact Factor
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    ABSTRACT: During a prospective surveillance using PCR for the detection of plasmid-mediated AmpC β-lactamase (pAmpC)-producing Enterobacteriaceae, outbreaks due to pAmpC-producing Klebsiella pneumoniae (pAmpC-Kp) occurred in an adult liver transplantation unit (aLTU) and a paediatric liver transplantation unit (pLTU), with carbapenem-resistant (CR) variants. Between April 2010 and March 2012, a total of 32 patients infected with pAmpC-Kp were found by prospective surveillance using PCR detection at a Japanese university hospital. Multilocus sequence typing, analysis of outer membrane proteins, and detection of carbapenemases were performed. Clinical courses of patients with bloodstream infection (BSI) were reviewed. Of 32 pAmpC-Kp isolates from each patient, 20 (18 from aLTU patients) were DHA-1-producing sequence type 11 (DHA-1-ST11), 9 were CMY-2-ST45/778 (all from pLTU patients) and the other 3 isolates had different sequence types. CR variants were isolated from 8 aLTU patients with DHA-1-ST11 and from 1 pLTU patient with CMY-2-ST45. All of the pAmpC-Kp isolates, including CR variants, were negative for carbapenemases. All of the DHA-1-ST11 and CMY-2-ST45 isolates lacked OmpK35, and seven CR variants also lacked OmpK36. BSIs due to DHA-1-ST11 isolates, including CR variants, occurred in six aLTU patients, four of whom died. The outbreaks were controlled after application of intensified infection control measures. During pAmpC-Kp outbreaks involving 27 liver transplants, CR variants with porin loss developed in nine patients, and DHA-1-ST11 K. pneumoniae caused BSIs with high mortality.
    International Journal of Antimicrobial Agents 10/2014; 45(1). DOI:10.1016/j.ijantimicag.2014.08.015 · 4.30 Impact Factor
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    ABSTRACT: Background Environmental exposure is a likely risk factor for the development of pulmonary Mycobacterium avium complex (MAC) disease. The influence of environmental exposure on the response to antimicrobial treatment and relapse is unknown. Methods We recruited 72 patients with pulmonary MAC disease (male [female], 18 [54]; age, 61.7 ± 10.3 years) who initiated and completed standard three-drug regimens for more than 12 months between January 2007 and December 2011. The factors associated with sputum conversion, relapse and treatment success without relapse were retrospectively evaluated after adjustments for confounding predictors. Results Fifty-two patients (72.2%) demonstrated sputum conversion, and 15 patients (28.8%) relapsed. A total of 37 patients (51.4%) demonstrated treatment success. Sputum conversion was associated with negative smears (odds ratio [OR], 3.89; 95% confidence interval [CI], 1.27-12.60; P = 0.02). A relapse occurred in patients with low soil exposure after the start of treatment less frequently than in patients with high soil exposure (7/42 [16.7%] vs. 8/10 [80.0%], P = 0.0003). Treatment success was associated with low soil exposure after the beginning of treatment (OR, 13.46; 95% CI, 3.24-93.43; P = 0.0001) and a negative smear (OR, 2.97; 95% CI, 1.02-9.13; P = 0.047). Conclusion Low soil exposure was independently associated with better microbiological outcomes in patients with pulmonary MAC disease after adjusting for confounding clinical, microbiological and radiographic findings.
    BMC Infectious Diseases 09/2014; 14(1):522. DOI:10.1186/1471-2334-14-522 · 2.61 Impact Factor
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    ABSTRACT: Vancomycin-resistant enterococci are important nosocomial pathogens that require rapid and accurate detection for infection control. Matrix-assisted laser desorption/ionisation time-of-flight mass spectrometry (MALDI-TOF/MS) has begun to be used in many clinical laboratories because it is a rapid, simple and inexpensive method for identifying micro-organisms. In this study, the performance of MALDI-TOF/MS to differentiate vanA-positive Enterococcus faecium (VPEF) from vanA-negative E. faecium (VNEF) was evaluated. A total of 61 VPEF isolates collected during regional surveillance in Kyoto (Japan) and 71 VNEF isolates collected from bacteraemia patients were analysed using MALDI-TOF/MS with three ClinProTools models. All of the isolates were correctly identified as E. faecium using the MALDI Biotyper system. To discriminate between VPEF and VNEF, all three ClinProTools models yielded >90% recognition capability (basic sensitivity) and cross-validation (reliability of the models); the genetic algorithm model exhibited the highest performance (99.18% and 92.40%, respectively). The high detection performance of MALDI-TOF/MS for VPEF offers the potential for routine laboratory use.
    International Journal of Antimicrobial Agents 09/2014; 44(3). DOI:10.1016/j.ijantimicag.2014.05.006 · 4.30 Impact Factor
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    ABSTRACT: We conducted this study to identify risk factors that may predict whether Candida spp. are causative agents of suspected catheter-related bloodstream infections (CRBSIs). All patients with laboratory-confirmed CRBSIs at Kyoto University Hospital between 2009 and 2011 were included. We compared the clinical features of candidal CRBSIs (78 cases) and non-candidal CRBSIs (258 cases). According to a multivariate analysis, a solid tumor (odds ratio (OR), 3.11; 95% confidence interval (CI), 1.75 - 5.53), total parental nutrition (OR, 2.65; 95% CI, 1.39 - 5.06), and the administration of anti-anaerobic agents (OR, 2.22; 95% CI, 1.03 – 4.79) were significantly more common among candidal CRBSIs. The 1-3 β-D-glucan test was positive among 94.6 % (35/37) of candidal CRBSI patients and 9.4 % (10/106) of non-candidal CRBSI cases. The administration of antifungal agents may be considered for patients with these risk factors, especially when the 1-3 β-D-glucan test is positive.
    Diagnostic Microbiology and Infectious Disease 08/2014; 80(3). DOI:10.1016/j.diagmicrobio.2014.08.003 · 2.46 Impact Factor
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    ABSTRACT: Patients with pulmonary Mycobacterium avium complex (MAC) disease are often co-infected with various pathogenic microorganisms. This study aimed to determine the prevalence of co-infection with non-MAC pathogens and the risk factors associated with co-infection in patients with pulmonary MAC disease. We retrospectively reviewed the patient characteristics, microbiological results and chest CT findings in 275 patients with pulmonary MAC who visited the Kyoto University Hospital from January 2001 to May 2013. We defined chronic pathogenic co-infection as the isolation of non-MAC pathogens from sputum samples taken on more than two visits that occurred at least 3 months apart. The participants were predominantly female (74.5%) and infected with M. avium (75.6%). Chronic co-infection with any pathogen was observed in 124 patients (45.1%). Methicillin-sensitive Staphylococcus aureus (MSSA; n=64), Pseudomonas aeruginosa (n=35) and Aspergillus spp (n=18) were the most prevalent pathogens. The adjusted factors were chronic obstructive pulmonary disease (COPD; OR=4.2, 95% CI 1.6 to 13.1) and pulmonary M. intracellulare disease (OR=2.2, 95% CI 1.1 to 4.4) in chronic co-infections; COPD (OR=4.2, 95% CI 2.1 to 31.4), long duration of MAC disease (OR=2.2, 95% CI 1.2 to 4.4) and nodules (OR=3.5, 95% CI 1.2 to 13.2) in chronic MSSA co-infection; COPD (OR=7.5, 95% CI 2.1 to 31.4) and lower lobe involvement (OR=9.9, 95% CI 2.0 to 90.6) in chronic P. aeruginosa co-infection; and use of systemic corticosteroids (OR=7.1, 95% CI 1.2 to 50.9) and pulmonary M. intracellulare disease (OR=4.0, 95% CI 1.1 to 14.5) in chronic Aspergillus spp co-infection. Patients with pulmonary MAC disease frequently had chronic co-infections with pathogenic microorganisms such as MSSA, P. aeruginosa and Aspergillus. The risk factors for chronic co-infection were COPD and pulmonary M. intracellulare disease.
    05/2014; 1(1):e000050. DOI:10.1136/bmjresp-2014-000050
  • K Kato · Y Matsumura · M Yamamoto · M Nagao · Y Ito · S Takakura · S Ichiyama
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    ABSTRACT: Bacillus cereus, an opportunistic pathogen, can cause fatal infection. However, B. cereus bloodstream infections (BSIs) have not been well characterised. From 2008 to 2013, B. cereus isolates from all of the specimens and patients with B. cereus BSIs were identified. Environmental samples were collected to detect B. cereus contamination. We also characterised the clinical presentation of B. cereus BSI through analyses of risk factors for BSI and mortality. A total of 217 clinical B. cereus isolates was detected. Fifty-one patients with nosocomial infections were diagnosed as B. cereus BSI, and 37 had contaminated blood cultures. The number of B. cereus isolates and BSI patients was significantly greater from June to September than from January to April (4.9 vs. 1.5 per month and 1.2 vs. 0.2, respectively). All BSIs were nosocomial and related to central or peripheral vascular catheter. Urinary catheter [odds ratio (OR) 6.93, 95 % confidence interval (CI) 2.40-20.0] was the independent risk factor associated with BSI patients when compared to patients regarded as contaminated. In-hospital mortality among BSI patients was 20 % and was associated with urinary catheter (OR 34.7, 95 % CI 1.89-63.6) and higher Charlson index (OR 1.99, 95 % CI 1.26-3.12). The number of B. cereus isolates and BSI increased during summer. Inpatients with indwelling vascular or urinary catheters should be carefully monitored for potential B. cereus BSIs.
    European Journal of Clinical Microbiology 03/2014; 33(8). DOI:10.1007/s10096-014-2083-1 · 2.67 Impact Factor
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    ABSTRACT: Invasive Aspergillus infection (IA) is a significant cause of morbidity in lung transplantation (LT). However, its optimal prophylaxis is unclear. We routinely administer itraconazole (ITCZ) prophylaxis to all patients undergoing LT. In this study, we retrospectively evaluated the duration of prophylaxis and risk factors of IA. Among 30 adult patients who underwent LT, 5 patients developed IA. All patients with IA stopped ITCZ treatment within 1 year. At least 1 year of ITCZ prophylaxis is essential for the prevention of IA. Cytomegalovirus infection, renal replacement therapy, and tracheotomy were risk factors for IA.
    Transplant Infectious Disease 03/2014; 16(2). DOI:10.1111/tid.12187 · 2.06 Impact Factor
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    ABSTRACT: Escherichia coli sequence type 131 (ST131) and ST405 are important clonal groups because they are associated with the global increase of extended-spectrum β-lactamase (ESBL) producers. Matrix-assisted laser desorption ionization-time of flight mass spectrometry (MALDI-TOF MS) is emerging as a rapid, inexpensive, and accurate method for bacterial identification. We investigated the detection performance of MALDI-TOF for the ST131 and ST405 clonal groups using 41 ST131-O25b, 26 ST131-O16, 41 ST405, and 41 other ST ESBL-producing isolates. Main spectra representing each clonal group were used for classification with Biotyper. The peak that had the highest area under the receiver-operating characteristic curve generated by ClinProTools was detected with FlexAnalysis, and an optimal signal to noise ratio cut-off was determined. The optimal detection models were generated by ClinProTools. Classification by Biotyper could detect the ST131-whole (O25b and O16 together) group with a sensitivity of 98.5% and specificity of 93.9%. With FlexAnalysis, a peak of 9720 Da detected the ST131-whole group with a sensitivity of 97.0% and a specificity of 91.5% at a cut-off value of 8.0. The ClinProTools models exhibited good performance for the detection of the ST131-whole group (sensitivity and specificity of 94.0% and 92.7%, respectively), the ST131-O25b group (95.1% and 98.2%, respectively), and the ST405 group (90.2% and 96.3%, respectively). MALDI-TOF MS had high detection performance for the ST131-whole, ST131-O25b, and ST405 clonal groups. MALDI-TOF MS should be considered as an alternative method to monitor the epidemiology of the ESBL-producing E. coli ST131 and ST405 clonal groups.
    Journal of clinical microbiology 01/2014; 52(4). DOI:10.1128/JCM.03196-13 · 3.99 Impact Factor
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    ABSTRACT: Pneumocystis polymerase chain reaction (PCR) and blood (1→3)-β-d-glucan assays are known to be useful for the diagnosis of Pneumocystis pneumonia (PCP). However, their impact on the outcome of clinically suspected PCP patients has not yet been elucidated. Between January 2008 and July 2011, we prospectively observed 190 immunocompromised patients who had ground-glass opacity on chest computed tomography scans and were suspected to have PCP. The blood β-d-glucan levels of these patients were measured, and PCR was used to detect Pneumocystis jirovecii in the respiratory samples. The 30-day mortality rates and related factors were assessed. The 30-day mortality rate of all included patients was 21.6%. Both β-d-glucan-positive (10.1%) and PCR-positive patients (15.0%) had significantly lower mortality rates than β-d-glucan-negative (28.1%) or PCR-negative patients (30.1%). All of the 13 definite PCP patients had positive PCR and β-d-glucan results, received anti-PCP treatments, and survived. Among the 72 patients who were negative for microscopic detection of P. jirovecii but received anti-PCP treatments, positive PCR results (odds ratio [OR], 0.14; 95% confidence interval [CI], 0.02-0.74), a high Sequential Organ Failure Assessment score (OR, 1.42; CI, 1.08-1.88), and positive β-d-glucan levels (OR 0.25, CI 0.06-1.02) were associated with mortality rates using stepwise logistic regression analyses. A positive Pneumocystis PCR or β-d-glucan test was a candidate predictor of survival in patients who were suspected of having PCP, even though negative for visual detection by microscopy.
    Journal of Infection and Chemotherapy 12/2013; 20(1-2). DOI:10.1016/j.jiac.2013.09.004 · 1.49 Impact Factor
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    ABSTRACT: Rationale: Polyclonal and mixed mycobacterial Mycobacterium avium complex (MAC) infection is observed in pulmonary MAC disease. Human living environments contain multiple species or genotypes of non-tuberculous mycobacterial strains and are considered sources of infection. Objectives: To investigate the association of environmental exposure with polyclonal and mixed mycobacterial infection in pulmonary MAC disease after adjustments for potential confounding diseases and conditions, and radiographic findings. Methods: We collected two separate sputum samples from 102 patients and single sputum samples from 18 patients in whom the second MAC strain was not isolated in our prospective cohort of pulmonary MAC disease. MAC isolates from sputum samples and patients' residential soils were used for variable number of tandem repeats (VNTR) analyses. Polyclonal and mixed mycobacterial MAC infections were defined as having different VNTR genotypes and other mycobacterial species, respectively. Monoclonal MAC infection was defined as all isolates showing a single VNTR genotype. Associations of the type of infection with clinical and radiographic findings, and environmental exposure were measured. Measurements and Main Results: Polyclonal and mixed mycobacterial MAC and monoclonal infections were observed in 42 and 78 patients, respectively. By stepwise regression analysis, patients with polyclonal and mixed mycobacterial MAC infections were associated with history of asthma [odds ratio (OR) 11.56, 95% confidence interval (CI) 1.41-255.77, P=0.021], high soil exposure (≥2 hours per week, OR 4.31, 95% CI 1.72-11.45, P<0.01), shower use in a bathroom (OR 4.57, 95% CI 1.28-23.23, P=0.018) and swimming in a pool (OR 9.69, 95% CI 1.21-206.92, P<0.01). Conclusions: Environmental exposure was associated with polyclonal and mixed mycobacterial MAC infection in pulmonary MAC disease.
    Annals of the American Thoracic Society 11/2013; 11(1). DOI:10.1513/AnnalsATS.201309-297OC
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    ABSTRACT: Stenotrophomonas maltophilia (SM) is an important nosocomial pathogen. Due to its intrinsic resistance to various therapeutic drugs, the optimal antimicrobial therapy is often delayed. From January 2005 to September 2012, we retrospectively compared drug susceptibilities, clinical backgrounds, and outcome of SM bacteremic patients (SM group) with these of other non fermentative gram negative bacilli bacteremic patients (non-SM group), at a tertiary-care hospital in Kyoto, Japan. Among the SM group, risk factors of 30-day mortality were evaluated. The SM group and non-SM group included 54 and 237 cases, respectively. Among the non-SM group, bacteremic patients due to Pseudomonas aeruginosa, Acinetobacter species, and other non-fermentative gram negative bacilli included 156, 68, and 13 patients, respectively. SM isolates were susceptible to trimethoprim-sulfamethoxazole and minocycline (82.0% and 100%, respectively). Non-SM isolates were susceptible to meropenem (88.6%), ceftazidime (88.6%), cefepime (85.2%), and amikacin (97.0%). Both SM and non-SM isolates were susceptible to levofloxacin (87.5% and 82.0%, respectively). The use of carbapenems, antipseudomonal cephalosporins, and isolation of SM within 30 days represented an independent risk factor for SM bacteremia. The 30 day mortality rate among the SM group was significantly higher compared with the non-SM group (35% vs 18%, odds ratio: 2.2, 95% CI: 1.2-4.3 p = 0.012). Among the SM group, an independent factor which was associated with 30-day mortality was the SOFA score. SM bacteremia showed a worse outcome compared with bacteremia due to non-SM. For the patients who present risk factors for SM bacteremia, empirical antimicrobial therapy including trimethoprim-sulfamethoxazole, minocycline or levofloxacin should be considered.
    Kansenshogaku zasshi. The Journal of the Japanese Association for Infectious Diseases 09/2013; 87(5):596-602. DOI:10.11150/kansenshogakuzasshi.87.596
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    ABSTRACT: The global increase of extended-spectrum β-lactamase (ESBL)-producing Escherichia coli is associated with the specific clonal group sequence type 131 (ST131). In order to understand the successful spread of ESBL-producing E. coli clonal groups, we characterized fluoroquinolone resistance determinants, virulence genotypes, and plasmid replicons of ST131 and another global clonal group, ST405. We investigated 41 ST131-O25b, 26 ST131-O16, 41 ST405, and 41 other ST (OST) ESBL-producing isolates, which were collected at seven acute care hospitals in Japan. The detection of ESBL types, fluoroquinolone resistance associated mutations including quinolone-resistance determining regions (QRDRs), virulence genotypes, plasmid replicon types, and IncF replicon sequence typing was performed using PCR and sequencing. blaCTX-M, specifically blaCTX-M-14, was the most common ESBL type among the four groups. Ciprofloxacin resistance was found in 90% of ST131-O25b, 16% of ST131-O16, 100% of ST405, and 54% of OST groups. Multidrug resistance was more common in the ST405 group than in the ST131-O25 group (56% vs. 32%, p=0.045). All ST131-O25b isolates except one had four characteristic mutations in QRDRs, but most of the isolates from the other three groups had three mutations in common. The ST131-O25b and ST405 groups had a higher number of virulence genes than the OST group. All of the ST131-O25b and ST405 isolates and most of the ST131-O16 and OST isolates carried IncF replicons. The most prevalent IncF replicon sequence types differed between the four clonal groups. Both the ST131-O25b and ST405 clonal groups had a fluoroquinolone resistance mechanism in QRDRs, multidrug resistance, high virulence, and IncF plasmids, which suggest a potential for further global expansion and a need for measures against these clonal groups.
    Antimicrobial Agents and Chemotherapy 07/2013; 57(10). DOI:10.1128/AAC.00641-13 · 4.48 Impact Factor
  • K Maekawa · Y Ito · T Oga · T Hirai · T Kubo · K Fujita · S Imai · A Niimi · K Chin · S Ichiyama · K Togashi · M Mishima
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    ABSTRACT: Kyoto, Japan. To validate the St George's Respiratory Questionnaire (SGRQ) in pulmonary Mycobacterium avium-intracellulare complex disease and to analyse the significance of high-resolution computed tomography (HRCT) findings as determinants of health-related quality of life (HRQoL) after adjusting for clinical and physiological parameters. Eighty-five patients completed the SGRQ, pulmonary function tests and other patient-reported measurements. HRCT findings were assessed using an established computed tomography (CT) scoring method. The SGRQ was validated with good internal consistency, test-retest reliability and significant correlations with most physiological variables and other patient-reported measurements. White blood cell counts, C-reactive protein levels, sputum culture results, treatment history, total CT scores, and consolidation, cavity and lobar volume-decrease CT component scores were significantly correlated with the SGRQ total and component scores. Stepwise multiple regression analyses revealed that the consolidation, cavity and lobar volume-decrease component scores were correlated with the SGRQ total and/or component scores. The total CT scores had the strongest relationships with the SGRQ total scores among the various clinical parameters tested, including microbiological, radiological, physiological and laboratory findings (32.8% of variance). HRCT findings, particularly consolidation, cavity and lobar volume-decreases, were the most significant clinical parameters related to patient HRQoL.
    The International Journal of Tuberculosis and Lung Disease 06/2013; 17(6):829-35. DOI:10.5588/ijtld.12.0672 · 2.32 Impact Factor

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  • 2002–2015
    • Kyoto University
      • • Department of Clinical Laboratory Medicine
      • • Department of Dermatology
      Kioto, Kyōto, Japan
  • 2003
    • Kawasaki Medical University
      • Department of Laboratory Medicine
      Kurasiki, Okayama, Japan
  • 1988–2002
    • Nagoya University
      • • Clinical Laboratory
      • • Division of General Medicine
      • • Division of of Internal Medicine
      Nagoya-shi, Aichi-ken, Japan
  • 1998
    • Vanderbilt University
      Nashville, Michigan, United States
  • 1997
    • Toho University
      Edo, Tōkyō, Japan