Yoshihito Otsuka

Corynebacterium resistens sp. nov., a New Multidrug-Resistant Coryneform Bacterium Isolated from Human Infections

ABSTRACT Five strains of an unknown, multidrug-resistant coryneform, gram-positive rod were isolated from blood, bronchial aspirate, and abscess specimens. Four of the five strains isolated were highly resistant to antimicrobial agents, including β-lactams, aminoglycosides, macrolides, quinolones, and tetracyclines, except for glycopeptides. In immunocompromised patients, bacteremia associated with this organism was rapidly fatal. This coryneform bacterium was nonmotile, lipophilic, and nonsaccharolytic. Lack of pyrazinamidase activity differentiated this organism from other lipophilic corynebacteria. Chemotaxonomic studies indicated that this multidrug-resistant coryneform bacterium belongs to the genus Corynebacterium. Comparative 16S rRNA gene sequencing and DNA-DNA hybridization analyses revealed that the five isolates were genetically identical and that they represent a new subline within the genus Corynebacterium, for which we propose the designation Corynebacterium resistens sp. nov. The type strain of Corynebacterium resistens is GTC 2026T (SICGH 158T, JCM 12819T, CCUG 50093T).

Diagnostic tests for influenza and other respiratory viruses: determining performance specifications based on clinical setting.

The lack of sensitivity of rapid immunoassays in detecting the novel 2009 H1N1 influenza virus infection has led to recommendations on influenza diagnostic testing for clinicians treating patients as well as advising clinicians on testing decisions. Studies have also shown that rapid immunoassays for seasonal influenza virus show considerable variability in performance characteristics, based on age of patient, prevalence of disease, course of infection, and the quality of the kit used. While public health authorities are currently focused on influenza virus diagnostics, a lack of sensitivity of rapid immunoassays for other viral respiratory pathogens has been widely reported, such as the very limited value of rapid immunoassays for the detection of respiratory syncytial virus in adults. In light of the lack of sensitivity of diagnostic tests for suspected 2009 H1N1 influenza virus infection, as well as their variable performance characteristics for seasonal influenza virus, a number of recommendations have been made by public health authorities advising clinicians on the need for clinical judgment as an important part of testing and treatment decisions as well as reliance on local epidemiologic and surveillance data. With the availability of new molecular methodologies that are user-friendly and allow the front-line physician as well as hospital infection control programs to significantly improve respiratory viral diagnostics, there is a need to carefully determine the most optimal diagnostic testing methodology based on the clinical setting. This review will describe the historical, current, and changing dynamics of respiratory virus infection diagnostics.

Antibiotic susceptibility survey of blood-borne MRSA isolates in Japan from 2008 through 2011

We conducted an antibiotic susceptibility survey of 830 blood-borne methicillin resistant Staphylococcus aureus collected from nationwide hospitals in Japan over a three-year period from January 2008 through May 2011. Antibiotic susceptibility was judged according to the criteria recommended by the Clinical Laboratory Standard Institute. Over 99% of the MRSA showed to be susceptible to teicoplanin, linezolid, sulfamethoxazole/trimethoprim and vancomycin, and over 97% of them were susceptible to daptomycin, arbekacin and rifampin. The majority of the MRSA strains showed resistant to minocycline, meropenem, imipenem, clindamycin, ciprofloxacin, cefoxitin, and oxacillin in the rates of 56.6, 72.9, 73.7, 78.7, 89.0, 99.5, and 99.9%, respectively. Among the MRSA strains, 72 showed reduced susceptibility to vancomycin, including 8 strains (0.96%) of vancomycin-intermediate S. aureus (VISA), 54 (6.51%) of heterogeneous vancomycin-intermediate S. aureus (hVISA), and 55 (5.63%) of β-lactam antibiotics-induced vancomycin resistant S. aureus (BIVR). Unexpectedly, among the 54 hVISA and 55 BIVR, 45 isolates (83.3% and 81.8%, respectively) showed both hVISA and BIVR phenotypes. A new trend of vancomycin resistance found in this study was that VISA strains were still prevalent among the bacteremic specimens. The high rates of the hVISA/BIVR two-phenotypic vancomycin resistance, and the prevalence of VISA in the bloodborne MRSA call attention in the MRSA epidemiology in Japan.

Mycobacterium shinjukuense sp. nov., a slowly growing, non-chromogenic species isolated from human clinical specimens.

Seven isolates of a slowly growing, non-chromogenic Mycobacterium species were obtained from sputum and bronchial lavage fluid samples from elderly patients in different regions of Japan. These isolates were distinguished from related non-tuberculous species by colony morphology, positive results for Tween hydrolysis, catalase at 68 °C, nitrate reductase and pyrazinamidase and negative results for semi-quantitative catalase, urease and arylsulfatase. The mycolic acid pattern obtained by HPLC revealed a single cluster of late-eluting mycolic acids similar to but different from those of Mycobacterium malmoense ATCC 29571(T). The 16S rRNA gene, 16S-23S internal transcribed spacer (ITS), rpoB and hsp65 sequences were unique in comparison with those of other mycobacteria. Comparison of 16S rRNA gene sequences showed that the isolates were most closely related to Mycobacterium tuberculosis H37Rv(T) (21 base differences in 1508 bp; 98.6 % 16S rRNA gene sequence similarity). A representative strain, GTC 2738(T), showed 91.9 % rpoB sequence similarity with Mycobacterium marinum strain M, 95 % hsp65 sequence similarity with Mycobacterium kansasii CIP 104589(T) and 81.1 % 16S-23S ITS sequence similarity with Mycobacterium gordonae ATCC 14470(T). Phylogenetic analysis of concatenated sequences of the 16S rRNA, rpoB and hsp65 genes showed that strain GTC 2738(T) was located on a distinct clade adjacent to M. tuberculosis, M. ulcerans and M. marinum, with bootstrap values of 81 %. DNA-DNA hybridization demonstrated less than 70 % reassociation with type strains of genetically related species and supported the novel species status of the isolates. On the basis of this evidence, a novel species with the name Mycobacterium shinjukuense sp. nov. is proposed. The type strain, isolated from a sputum sample, is strain GTC 2738(T)( = JCM 14233(T) = CCUG 53584(T)).

Genetic Identification of Members of the Genus Corynebacterium at Genus and Species Levels with 16S rDNA-Targeted Probes

16S rRNA gene‐targeted probes were designed for the identification of corynebacteria at the genus and species levels. The genus‐specific probe hybridized all clinically important members of the genus Corynebacterium and could distinguish them from other coryneform bacteria and phylogenetically related high G + C% gram‐positive bacteria, including Actinomyces, Rhodococcus, Gordona, Nocardia, Streptomyces, Brevibacterium and Mycobacterium. The species‐specific probes for C. jeikeium and C. diphtheriae could differentiate these two species from other members of this genus. The probes were used to select corynebacteria among gram‐positive clinical isolates which had been tentatively identified as corynebacteria by biochemical tests. We screened 59 strains with the genus‐specific probe; 51 strains hybridized to the genus‐specific probe, 8 did not. Of the 51 strains that hybridized to the genus‐specific probe, 1 hybridized to the C. diphtheriae species probe and 13 hybridized to the C. jeikeium species probe. The 8 strains that did not hybridize to the genus probe were further characterized by analyzing cell wall diaminopimelic acid and partial 16S rRNA sequencing. The results indicated that these strains were distributed in the genera Arthrobacter and Brevibacterium.

Clinical Features of Community-Acquired Helicobacter cinaedi Bacteremia.

There are growing numbers of reports concerning the clinical and pathological features of Helicobacter cinaedi (H. cinaedi) bacteremia; however, few reports have discussed the features of this condition in healthy individuals.

公衆浴場での溺水後発症したLegionella pneumophila serogroup 6による劇症肺炎の1例

A 57-year-old male was admitted to our hospital because of high fever, productive cough and dyspnea. Six days prior to admission he had an episode of drowning in a public bath. On admission chest X-ray showed wide-spread pneumonia causing severe respiratory distress for which mechanical ventilatory support was started. Despite chemotherapy including erythromycin and rifampicin his condition continued to deteriorate. Chemistry showed marked elevation of CPK and findings of acute renal failure. He eventually passed away with septic shock. During the course Legionellae remained negative with culture of broncho-alveolar lavage fluid. L. pneumophila serogroup 1 (SG1) antigen in the urine was not detected, and no elevation of serum antibody titer was noted. Culture of the material obtained from the lung abscess at autopsy revealed L. pneumophila SG6 and serum antibody titer against SG6 also was found to be extremely high. With this evidence we concluded that this case of pneumonia was caused by L. pneumophila SG6. We believe this is the first reported case of the SG6 pneumonia in Japan. Another remarkable feature of this case was massive rhabdomyolysis pathologically confirmed after autopsy. Although the pathogenesis of this process has not been clarified, there are several case reports of rhabdomyolysis complicated with Legionnairs disease in the past. Therefore, we should bear in mind and pay careful attention while coping with this disease.

Recurrence of Disseminated Mycobacterium avium Complex Disease in a Patient with Anti-Gamma Interferon Autoantibodies by Reinfection

ABSTRACT We report a case of recurrent disseminated Mycobacterium avium complex (DMAC) disease with anti-gamma interferon autoantibodies. To our knowledge, this is the first reported case caused by reinfection with a separate isolate of M. avium. DMAC disease activity was monitored using serum IgG antibody titers against lipid antigens extracted from a MAC strain.

Profile of infective endocarditis at a tertiary-care hospital in Japan over a 14-year period: characteristics, outcome and predictors for in-hospital mortality

OBJECTIVES The aims of this study were to describe the epidemiological features and clinical characteristics of infective endocarditis (IE) at a tertiary-care hospital in Japan and to identify the factors associated with in-hospital mortality. METHODS A retrospective observational study was conducted at a 925-bed tertiary-care teaching hospital in Japan. All adult patients diagnosed with definite IE between August 2000 and July 2014 according to the modified Duke criteria were included. RESULTS A total of 180 patients (60.6% men; mean age, 69.1 years) with definite IE were included. The most common pathogen was Staphylococcus aureus (27.2%). Nine patients (5.0%) had culture-negative IE. Transthoracic and transoesophageal echocardiography were performed in 180 (100%) and 132 patients (73.3%), respectively, and vegetations were detected in 128 patients (71.1%). Surgical therapy was performed in 31 patients (17.2%). Overall, the in-hospital mortality rate was 26.1%. The independent predictors of in-hospital mortality were methicillin-resistant S. aureus (MRSA), vascular phenomena, health care-associated IE and heart failure. CONCLUSIONS MRSA, vascular phenomena, health care-associated IE and heart failure were independent predictors of in-hospital mortality. The unique characteristics in our cohort were the very high mean age, low rate of culture-negative IE, high rate of definite IE without detected vegetations and predominance of S. aureus.

Non-HIV Pneumocystis pneumonia: do conventional community-acquired pneumonia guidelines under estimate its severity?

BackgroundNon-HIV Pneumocystis pneumonia (PCP) can occur in immunosuppressed patients having malignancy or on immunosuppressive agents. To classify severity, the A-DROP scale proposed by the Japanese Respiratory Society (JRS), the CURB-65 score of the British Respiratory Society (BTS) and the Pneumonia Severity Index (PSI) of the Infectious Diseases Society of America (IDSA) are widely used in patients with community-acquired pneumonia (CAP) in Japan. To evaluate how correctly these conventional prognostic guidelines for CAP reflect the severity of non-HIV PCP, we retrospectively analyzed 21 patients with non-HIV PCP.MethodsA total of 21 patients were diagnosed by conventional staining and polymerase chain reaction (PCR) for respiratory samples with chest x-ray and computed tomography (CT) findings. We compared the severity of 21 patients with PCP classified by A-DROP, CURB-65, and PSI. Also, patients’ characteristics, clinical pictures, laboratory results at first visit or admission and intervals from diagnosis to start of specific-PCP therapy were evaluated in both survivor and non-survivor groups.ResultsBased on A-DROP, 18 patients were classified as mild or moderate; respiratory failure developed in 15 of these 18 (83.3%), and 7/15 (46.7%) died. Based on CURB-65, 19 patients were classified as mild or moderate; respiratory failure developed in 16/19 (84.2%), and 8 of the 16 (50%) died. In contrast, PSI classified 14 as severe or extremely severe; all of the 14 (100%) developed respiratory failure and 8/14 (57.1%) died. There were no significant differences in laboratory results in these groups. The time between the initial visit and diagnosis, and the time between the initial visit and starting of specific-PCP therapy were statistically shorter in the survivor group than in the non-survivor group.ConclusionsConventional prognostic guidelines for CAP could underestimate the severity of non-HIV PCP, resulting in a therapeutic delay resulting in high mortality. The most important factor to improve the mortality of non-HIV PCP is early diagnosis and starting of specific-PCP therapy as soon as possible.