Kazuhiko Irinoda

Characterization of pKU701, a 2.5-kb plasmid, in a Japanese Helicobacter pylori isolate.

A cryptic plasmid of Helicobacter pylori, pKU701 (accession number AB078638), was isolated and the complete nucleotide sequence was determined. No drug resistance properties were mediated by pKU701. The 2454b pKU701 sequence, which had a 38% content of G-C residues, generated one polypeptide from a single open reading frame (ORF1). Extensive sequence homology was evident between pKU701 and ORF1 of H. pylori plasmid pHPO100 (repA, 88.8% identity) as well as ORF3 of plasmid pHPS1 (repB, 80.2% identity), but pKU701 showed only 46.3% homology with ORF1 of plasmid pHPK255 (repA). Tandem direct repeats of a 33-bp segment were found in pKU701 outside ORF1, but there were no inverted repeat ends such as those found in typical insertion sequences. The ability of drug resistance plasmids to replicate in H. pylori is probably limited, so chromosomal mutation may be a more likely cause of resistance.

Investigation of methicillin-resistant Staphylococcus aureus showing reduced vancomycin susceptibility isolated from a patient with infective endocarditis

A patient with infective endocarditis (IE) caused by methicillin-resistant Staphylococcus aureus (MRSA) was treated with vancomycin (VAN). VAN was ineffective, although therapeutic drug monitoring (TDM) indicated that the recommended trough level was maintained. Five MRSA isolates obtained at various times were analyzed to determine the minimum inhibitory concentration (MIC) and were subjected to population analysis, simulation analysis pulsed-field gel electrophoresis (PFGE). MRSA susceptible to VAN was isolated before and during the early stage of treatment, while an MRSA strain showing reduced VAN MIC was isolated during treatment. Simulation analysis indicated that the viable bacterial count only decreased to 10(-3) to 10(-4) cells after 72 h of incubation. The five MRSA strains isolated at various times were identical by PFGE.

Use of the restriction enzyme EcoRI for pulsed-field gel electrophoretic analysis of Helicobacter pylori.

ABSTRACT Pulsed-field gel electrophoretic (PFGE) analysis of Helicobacter pylori isolates is not commonly employed because of the inability to compare the typing with other typing systems. We adapted the PFGE analysis for H. pylori by using EcoRI and slightly modified our laboratory methods to improve the typing of isolates (typeability was 97%).