Isamu Nakasone

Nosocomial outbreak of multidrug‐resistant USA300 methicillin‐resistant Staphylococcus aureus causing severe furuncles and carbuncles in Japan

USA300 methicillin‐resistant Staphylococcus aureus (MRSA) has been attracting worldwide attention as a cause of community‐associated MRSA (CA‐MRSA) infections in the 21st century. Nosocomial outbreaks of CA‐MRSA clones have been progressively more reported in Europe and the USA, but only one very recent report from Kyoto found in Japan. In February 2008, a severe MRSA infection occurred in one immunocompromised patient and three healthy medical staff members at the Department of Dermatology, Graduate School of Medicine, University of the Ryukyus. The epidemiological and clinical pattern of the infection prompted us to characterize the molecular features of the MRSA strain involved. The causative MRSA strain belonged to the multi‐locus sequence type 8, staphylococcal cassette chromosome mec (SCCmec) type IVa, spa1 (alternatively t008), agr1 and coagulase type III, and carried the Panton–Valentine leukocidin (PVL) gene and the arginine catabolic mobile element. Pulsed‐field gel electrophoresis analysis showed that the MRSA responsible for the outbreak was the USA300 clone. All of the isolated USA300 clones had multiple resistance against six non‐β‐lactam antimicrobial drugs. We report here the first nosocomial outbreak of multidrug‐resistant USA300 MRSA infections in Japan. This report shows that the USA300 clone can manifest severe skin infections such as furuncles and carbuncles even in healthy persons, which require drainage and i.v. treatment, and suggests that the clone can spread in hospital settings worldwide.

Oral candidiasis in patients receiving radiation therapy for head and neck cancer

OBJECTIVE: To investigate oral candidiasis in patients with head and neck cancer before, during, and after radiation therapy, and to explore its association with clinical oropharyngeal symptoms. STUDY DESIGN: A cohort study. SETTING: University hospital. SUBJECTS AND METHODS: Subjects who received radiation therapy (RT) for the treatment of head and neck cancer were divided into two groups: an oral cavity irradiated group (OIRR group, n = 29) and an oral cavity nonirradiated group (ONIRR group, n = 17). A control group consisted of 18 healthy subjects. Patients were examined for signs of oral candidiasis before, during, immediately after, and one month after RT. Mouth and throat soreness (MTS), dysphagia, and xerostomia were evaluated by self-reported questionnaires, and associations between oral candidiasis and these symptoms were analyzed. RESULTS: The incidence of oral candidiasis during RT was significantly higher in the OIRR group (55.2%) than in the ONIRR group (11.8%). Similarly, the occurrence of xerostomia during RT was significantly higher in the OIRR group (86.2%) than in the ONIRR group (52.9%). In the OIRR group, the mean MTS score at the 20th fraction of RT was significantly higher in patients with candidiasis (mean ± SD, 5.8 ± 2.1) than in those with RT-induced mucositis without candidiasis (3.7 ± 2.0). In the OIRR group, 65.2 percent of patients who experienced dysphagia developed oral candidiasis, compared with only 10 percent in the ONIRR group. CONCLUSION: Oral candidiasis concurrent with oral mucositis due to RT may increase oropharyngeal discomfort during RT.

Detection of Legionella Species in Clinical Samples: Comparison of Polymerase Chain Reaction and Urinary Antigen Detection Kits

Background:Recently, two excellent methods have been used for the diagnosis of Legionnaires’ disease: urinary antigen detection and PCR. The purpose of the present study is to analyze and evaluate the sensitivity and specificity of three different urinary antigen detection kits as well as PCR.Materials and Methods:A total of 148 samples were collected from 33 patients between 1993 and 2004. These consisted of 73 urine samples obtained from 33 patients, 57 serum samples provided by 29 patients, and 18 respiratory tract specimens from 13 patients. Three commercially available kits were used to detect urinary antigen. For the 5S PCR reaction, primers L5SL2 and L5SR84 were used.Results:Positive results were shown in all patients’ urine (representing 79.5% of total samples) using the Binax EIA kit, in 93.9% patients (representing 75.3% samples) using the Binax NOW immunochromatographic kit, and in 90.9% (representing 72.6% samples) using the Biotest EIA kit. Urine samples from 12.1% patients (representing 6.8% of total samples), serum samples from 41.4% patients (representing 35.1% of total samples), and respiratory samples from 84.6% patients (representing 88.9% of total samples) showed positive results with PCR.Conclusion:In testing urine of legionellosis patients, it was suggested that three kits were all valuable tools for diagnosis of legionellosis. Since over one-third of patients’ serum samples and most respiratory specimens showed positive results with PCR, the addition of PCR for testing of these samples might be useful, particularly in cases of culture negative and serum antibody negative patients.

Dissemination of Panton–Valentine leukocidin-positive methicillin-resistant Staphylococcus aureus in Okinawa, Japan

Panton–Valentine leukocidin (PVL) is a pore‐forming cytotoxin that is produced by Staphylococcus aureus closely associated with skin and soft‐tissue infections (SSTI). PVL‐positive S. aureus strains have been identified worldwide, including in the USA; however, few studies have reported the presence of these strains in Japan. In this study, we prospectively investigated the prevalence of PVL in S. aureus strains from outpatients presenting with SSTI in Okinawa and characterized the PVL‐positive S. aureus strains by polymerase chain reaction (PCR) and multilocus sequence typing (MLST). From 2008–2010, 499 clinical samples were obtained from 497 people. S. aureus was identified in 274 samples, and 36% (99 of 274) were methicillin‐resistant S. aureus (MRSA). Seventeen (6.2%) PVL‐positive S. aureus strains were detected by PCR, and 12 of the 17 PVL‐positive strains were MRSA. Most PVL‐positive S. aureus caused furuncles or carbuncles. Nine of the 17 PVL‐positive isolates had an ST8 MRSA genotype and most harbored SCCmec type IVa and the arcA gene of the arginine catabolic mobile element, which is identical to the USA300 clone prevalent in the USA. PVL‐positive S. aureus strains were more likely to be resistant to erythromycin (65%) and levofloxacin (53%). PVL‐positive S. aureus strains have emerged and are spreading as a causative pathogen for SSTI in Okinawa.

Comparison of drug sensitivity and genotypes of clinically isolated strains of levofloxacin-resistant Streptococcus pneumoniae obtained from Okinawa Island, the Japanese main island and Hong Kong

The prevalence of fluoroquinolone-resistant Streptococcus pneumoniae is increasing worldwide. In the present study, a comparison of drug sensitivity and genotypes of clinically isolated strains of levofloxacin (LVFX)-resistant S. pneumoniae obtained from Hong Kong, Okinawa Island and the Japanese main island (Honshu) was performed. MICs of quinolones (LVFX, tosufloxacin, ciprofloxacin, gatifloxacin and sitafloxacin (STFX)) and other antibiotics (penicillin G, cefcapene, cefditoren, clarithromycin and azithromycin) were determined by a microdilution broth method according to the Clinical and Laboratory Standards Institute Standards. The quinolone-resistance determining regions (QRDRs) of gyrA, gyrB, parC and parE of these strains were analyzed by PCR-based sequencing. All 40 strains tested had more than one amino-acid substitution in the QRDRs of gyrA, gyrB, parC or parE. Although there seemed to be some clonality in strains obtained from Hong Kong, there was no clonality in strains obtained from Okinawa and Japan. Strains obtained from Hong Kong, Okinawa Island and the Japanese main island were genetically different by pulsed-field gel electrophoresis analysis. The range of MIC values of STFX against isolates resistant to LVFX (MIC 4–32 mg l−1) was 0.12–0.5 mg l−1, and MIC80 values of STFX against LVFX-resistant isolates were 0.25 mg l−1. This study suggests that LVFX-resistant S. pneumoniae is similar in all three locations and STFX is potent against LVFX-resistant S. pneumoniae with multiple mutations in QRDRs of gyrase A and topoisomerase IV.

Emergence of a colistin-resistant Escherichia coli clinical isolate harboring mcr-1 in Japan

The mcr-1 is a gene encoding a phosphoethanolamine transferase, which confers resistance to colistin by transferring phosphoethanolamine to lipid A. We describe here the emergence of a colistin-resistant Escherichia coli clinical isolate harboring plasmid-mediated mcr-1 in Japan. The isolate belonged to ST5702 and is suspected to come from livestock and transmitted to human. This is the first report of a clinical isolate harboring mcr-1 in Japan.

A Modified Carbapenem Inactivation Method, CIMTris, for Carbapenemase Production in Acinetobacter and Pseudomonas Species

ABSTRACT The carbapenem inactivation method (CIM) and modified CIM (mCIM) are simple and economical phenotypic screening methods for detecting carbapenemase production in Gram-negative bacteria. Although the mCIM has been recommended by the Clinical and Laboratory Standards Institute, both the CIM and mCIM have limitations. This study describes another modified CIM, called CIMTris, in which carbapenemase was extracted from bacteria with 0.5 M Tris-HCl (pH 7.6) buffer. The ability of the CIMTris to detect carbapenemase production was examined in Acinetobacter and Pseudomonas species. The CIMTris had an overall sensitivity of 97.6% and an overall specificity of 92.6%, whereas the mCIM had a sensitivity of 45.1% and a specificity of 100% for the isolates tested. These findings indicate that the CIMTris is useful for detecting carbapenemase production in Acinetobacter and Pseudomonas species.

A hemin auxotrophic Enterobacter cloacae clinical isolate with increased resistance to carbapenems and aminoglycosides

Small-colony variants (SCVs) were obtained from an Enterobacter cloacae clinical isolate in Okinawa, Japan. One variant showed auxotrophy for hemin with a deletion of 20 365 nucleotides, dosC-ydiK-mmuP-mmuM-tauA-tauB-tauC-tauD-hemB-yaiT-yaiV-ampH-yddQ-sbmA-yaiW-yaiY-yaiZ, including hemB, and was more resistant to aminoglycosides and carbapenems, but more susceptible to aztreonam, than the parent strain.

Emergence of IncX4 plasmids encoding mcr-1 in a clinical isolate of Klebsiella pneumoniae in Japan

The mcr-1 gene encodes a phosphoethanolamine transferase that confers resistance to colistin by transferring phosphoethanolamine to lipid A. A 33-kb IncX4 plasmid harboring mcr-1 was detected in a Klebsiella pneumoniae isolate and two Escherichia coli isolates, and a 66-kb IncI2 plasmid was detected in three E. coli isolates in hospitals in Okinawa, Japan.