Kenta Utsumi

Using the tannase gene to rapidly and simply identify Staphylococcus lugdunensis

The coagulase-negative Staphylococcus lugdunensis, a bacterium similar to Staphylococcus aureus, produces tannase that degrades tannin. We developed a polymerase chain reaction-based method to rapidly and simply identify this species by detecting the tanA gene for S. lugdunensis tannase.

Characterization of methicillin-resistant Staphylococcus aureus isolated from tertiary care hospitals in Tokyo, Japan

The prevalence of methicillin-resistant Staphylococcus aureus (MRSA) remains problematic in both hospital and community settings. Investigations of MRSA existing in the local area are necessary to understand the detailed epidemiology of healthcare-associated MRSA (HA-MRSA). In the present study, molecular epidemiological analysis was performed on 584 MRSA isolated from four hospitals in Tokyo, Japan. In the pulsed-field gel electrophoresis (PFGE) analysis, four epidemic pulsotypes (I to IV) were found. The isolates of the epidemic pulsotype I mainly consisted of the SCCmec type II, toxic shock syndrome toxin 1 gene (tst)-negative, spa type t002, and ST764 clones. The ST764 clone, which is a novel hybrid variant of the ST5 HA-MRSA lineage with the arginine catabolic mobile element (ACME), was first found in Niigata, Japan. However, no ACME genes were detected in the isolates of the epidemic pulsotype I. In contrast, the other isolates of the epidemic pulsotypes mainly consisted of the SCCmec type II, tst-positive, spa type t002, and ST5 clones, which are the most predominant clones of HA-MRSA in Japan. Resistance rates of non-β-lactams for the isolates of the epidemic pulsotype I were higher than those of the other epidemic pulsotypes. Our data showed that the novel ACME-negative ST764 clones are being distributed throughout multiple hospitals in Tokyo. The ST764 clones in Tokyo have the potential to acquire ACME in the future, because the ACME-positive ST764 clones have already been found in both hospital and community settings in other areas of Japan.

Increase in SCCmec type IV strains affects trends in antibiograms of meticillin-resistant Staphylococcus aureus at a tertiary-care hospital.

The prevalence of community-acquired meticillin-resistant Staphylococcus aureus (CA-MRSA) strains has become a serious problem worldwide. The aim of this study was to investigate the annual transitions of MRSA strains with the CA-MRSA feature, which were identified as SCCmec type IV or V, in a hospital setting in Japan. Between 2005 and 2012, MRSA strains were collected from a tertiary-care hospital in Tokyo, Japan, and SCCmec typing, detection of the virulence factors and antimicrobial susceptibility testing were conducted. The rate of detection of type II SCCmec, which is found mainly in healthcare-associated MRSA, significantly decreased from 90.0 (2005-2006) to 74.3 % (2011-2012) (P < 0.01). In contrast, the rate of detection of type IV SCCmec, which is mainly found in CA-MRSA, significantly increased from 5.8 (2005-2006) to 16.3 % (2011-2012) (P < 0.01). The rate of detection of the toxic shock syndrome toxin-1 gene significantly decreased from 66.7 (2005-2006) to 51.6 % (2011-2012) (P < 0.01), whilst that of the Panton-Valentine leukocidin gene significantly increased from 0.1 (2005-2006) to 2.1 % (2011-2012) (P < 0.01). The resistance rates of cefotaxime, levofloxacin, clarithromycin and minocycline decreased every year. The resistance rates of these antimicrobial agents for the SCCmec type IV or V strains were significantly lower than those for the SCCmec type I or II strains (P < 0.01, respectively). Therefore, these results suggest that the annual transitions of the virulence factors and antibiograms in MRSA are closely related to the increase of SCCmec type IV/V strains.

Change in environmental bacterial flora in a new hospital building

Microbial surveillance of environmental bacteria was performed in order to study the microbial changes in a newly established hospital building. Airborne bacteria and surface-associated bacteria on floors and sinks were systematically collected between 2002 and 2005. The number of isolates obtained from frequently used floors was significantly higher than that obtained from those floors used less often. A significant increase in Staphylococcus aureus, the appearance of Pseudomonas aeruginosa, and changes among species of Gram-negative bacilli were observed 8-11 months after the new building had been opened. Furthermore, pulsed-field gel electrophoresis (PFGE) typing of meticillin-resistant S. aureus (MRSA) and P. aeruginosa showed that strains of the same PFGE groups were isolated from different sinks, floors and the adjoining old buildings. The number of MRSA isolates obtained from the new building increased as time passed. The sinks from which P. aeruginosa strains of the same PFGE type were isolated are connected by the same drainage pipe. Human movement has considerable effects on bacterial flora and their subsequent spread.

Increased collagenase activity in macrophages from bronchial lavage as a diagnostic marker of non-small cell lung cancer.

Background: The roles of matrix metalloproteinases (MMPs) in cancer metastasis have been studied. Macrophages are considered to release MMPs in the tissues of patients with lung cancer. Methods: Intracellular collagenase activity was measured in CD14+ CD45+ cells from bronchial lavage fluid to establish a new diagnostic tool for lung cancer. Between August 2000 and November 2001 bronchoscopy and bronchial lavage were performed in 45 patients with abnormal shadows on the chest radiograph; 21 had lung cancer and 24 had non-malignant disease. Results: Collagenase activity in patients with primary lung cancer (5.54 (0.65)) or non-small cell lung cancer (NSCLC) (5.62 (0.71)) was significantly higher than in those with non-malignant disease (3.63 (0.78), p=0.006 and p=0.008, respectively). Only three of 18 patients in the low activity group were diagnosed as having cancer compared with 18 of 27 in the high activity group (p=0.001). This significance was not seen in non-smokers but it was apparent in smokers/ex-smokers. Excluding non-smokers improved the specificity of collagenase activity in differentiating cancer and non-malignant disease from 62.5% to 80.0%. The sensitivity of the test was 85.7% in all patients and 88.2% in smokers/ex-smokers. Conclusions: Measurement of intracellular collagenase activity in macrophages in bronchial lavage fluid is a useful diagnostic tool for distinguishing between cancer and non-malignant diseases, especially in smokers and ex-smokers.

Circulating and Tumor-Infiltrating γδ T Cells in Patients with B-Cell Lymphomas

In order to analyze the involvement of γδ T cells in the immune surveillance against B cell lymphomas (BCL), we investigated the proportion of circulating γδ T cells in 52 BCL patients using two-color flow cytometry, together with tumor-infiltrating γδ T cells in 22 of those patients. We found that the proportion of tumor-infiltrating γδ T cells in BCL patients was not different from that of lymph node γδ T cells in reactive hyperplasia patients. However, a decreased percentage of circulating γδ T cells were observed in indolent lymphoma (IL) and limited aggressive lymphoma (AL) patients when compared with normal controls. In contrast, as a result of a histogram. advanced AL patients were divided into two subgroups: the patients with increased circulating γδ T cells anti those without any increase. However, there was no difference in the clinical features of between the two AL subgroups.