Nobuhiro Iwakura

A Panton-Valentine Leucocidin (PVL)-Positive Community-Acquired Methicillin-Resistant Staphylococcus aureus (MRSA) Strain, Another Such Strain Carrying a Multiple-Drug Resistance Plasmid, and Other More-Typical PVL-Negative MRSA Strains Found in Japan

ABSTRACT Community-acquired methicillin-resistant Staphylococcus aureus (CA-MRSA) was collected from children with bullous impetigo in 2003 and 2004. One strain collected in 2003 was Panton-Valentine leucocidin (PVL) positive. In 2004, a multiple-drug-resistant PVL+ CA-MRSA strain was isolated from an athlete with a cutaneous abscess. These strains were analyzed by multilocus sequence typing, spa typing, agr typing, coagulase typing, staphylococcal cassette chromosome mec (SCCmec) typing, PCR assay for 30 virulence genes, drug susceptibility testing, pulsed-field gel electrophoresis, and for plasmids. The two Japanese PVL+ CA-MRSA strains belonged to the globally extant (“pandemic”) sequence type 30 (ST30) with SCCmec IV. A transmissible, multiple-drug resistance plasmid emerged in such ST30 strains. The PVL− CA-MRSA strains (“domestic” CA-MRSA) accumulated for bullous impetigo, exhibiting new genotypes. Hospital-acquired MRSA of ST91 (but not pandemic ST5) shared common features with the PVL− CA-MRSA strain.

A Novel Action of the Proton Pump Inhibitor Rabeprazole and Its Thioether Derivative against the Motility of Helicobacter pylori

ABSTRACT The motility of Helicobacter pylori was maximum at 37°C and at pH 6. A newly developed proton pump inhibitor, rabeprazole (RPZ), and its thioether derivative (RPZ-TH) markedly inhibited the motility of H. pylori. The concentrations of the drug necessary to inhibit 50% of the motility were 0.25, 16, 16, and >64 μg/ml for RPZ-TH, RPZ, lansoprazole, and omeprazole, respectively. No such inhibitory effects were observed with H2 blockers or anti-H. pylori agents. The motilities of Campylobacter jejuni and C. coli—but not those of Vibrio cholerae O1 and O139,Vibrio parahaemolyticus, Salmonella entericaserovar Typhimurium, and Proteus mirabilis—were also inhibited. Prolonged incubation with RPZ or RPZ-TH inhibited bacterial growth of only H. pylori, except for a turbid colony mutant. The results indicate that RPZ and RPZ-TH have a characteristic inhibitory effect against the motility of H. pylori(spiral-shaped bacteria), which is distinguished from that against bacterial growth.

60Co irradiation of Shiga toxin (Stx)‐producing Escherichia coli induces Stx phage

Shiga toxin (Stx)-producing Escherichia coli (STEC), an important cause of hemolytic uremic syndrome, was completely killed by (60)Co irradiation at 1 x l0(3) gray (1 kGy) or higher. However, a low dose of irradiation (0.1-0.3 kGy) markedly induced Stx phage from STEC. Stx production was observed in parallel to the phage induction. Inactivation of Stx phage required a higher irradiation dose than that for bacterial killing. Regarding Stx, cytotoxicity was susceptible to irradiation, but cytokine induction activity was more resistant than Stx phage. The findings suggest that (1). although (60)Co irradiation is an effective means to kill the bacteria, it does induce Stx phage at a lower irradiation dose, with a risk of Stx phage transfer and emergence of new Stx-producing strains, and (2). irradiation differentially inactivates some activities of Stx.