[Evaluation of rapid antimicrobial susceptibility test for Staphylococcus aureus by chemiluminescent assay and its application for screening of beta-lactam antibiotic induced vancomycin-resistant MRSA].

Minimum inhibitory concentrations (MICs) of vancomycin (VCM) and teicoplanin (TEIC) were measured using a novel susceptibility test based on the chemiluminescence assay method (CA) (Rapid-Lumi Eiken; Eiken Chemicals, Tokyo, Japan) against 84 strains of Staphylococcus aureus, consisting of 82 strains of methicillin-resistant S. aureus (MRSA) from clinical isolated, S. aureus Mu3 involving beta-lactam antibiotic induced vancomycin (VCM) resistant MRSA (BIVR) and methicillin-susceptible S. aureus ATCC 29213. The results were in good accordance with the values determined by Clinical and Laboratory Standards Institute (CLSI): i.e., 100% (84/84) of consistency for VCM and 95% (80/84) for TEIC, respectively. In addition, BIVR strains were properly estimated from the results of the CA method and using the BIVR detection method with Mu3 agar (Mu3 Agar method), even though the incubation times was very short (2-4 h). In conclusion, it was found that the new method is reliable and rapid to detect BIVR strains in clinical laboratories.

A chromogenic substrate culture plate for early identification of Vibrio vulnificus and isolation of other marine Vibrios.

Vibrio vulnificus infection can result in necrotizing fasciitis and sepsis, which have short latentcy periods and high mortality rates. Thus, an easy and quick detection method is needed to improve the outcome. To distinguish V. vulnificus from other pathogens that cause necrotizing fasciitis, we developed a selective isolation culture agar plate (Chromochecker Vibrio Agar-1; CVA-1) for use in environmental monitoring and in the clinical setting. One hundred four strains of V. vulnificus, already identified biochemically, showed typical colony form and color when grown on CVA-1. Thirty-six of 51 marine bacteria samples suspected to be V. vulnificus on CVA-1 were subsequently identified as V. vulnificus by a biochemical identification system. Of 8 bacteria known to cause necrotizing fasciitis, only V. vulnificus grew on CVA-1. In addition, growth on CVA-1 allowed ready differentiation of Vibrio species. CVA-1 can be used to distinguish pathogenic Vibrios according to colony form and chromatic differences.

[Evaluation of Dipstick 'Eiken' Legionella for detection of Legionella pneumophila serogroup 1 urinary antigen using the immunochromatographical method].

Dipstick 'Eiken' Legionella is a reagent for detection of Legionella pneumophila serogroup 1 antigen in urine using the immunochromatographical method. The reagent was evaluated using the reference and clinical isolated strains and clinical specimens. BinaxNOW Legionella and Legionella antigen [Mitsubishi] were evaluated simultaneously. Using four of L. pneumophila serogroup 1 strains, the minimal detectable concentration of Dipstick 'Eiken' Legionella was 5.0 x 10(4) to 2.0 x 10(5) colony forming unit/ml, it was approximate four times high in comparison with other two kits. And no positive reaction was obtained from 45 of non-L. pneumophila serogroup 1 strains. When Dipstick 'Eiken' Legionella was compared with BinaxNOW Legionella among 50 urine samples obtained from patients with pneumonia and 50 urine from healthy adults, the sensitivity was 94.7%, the specificity was 100.0% and the agreement was 99.0%. Dipstick 'Eiken' Legionella is found to be useful diagnostic reagent for Legionella infection in clinical laboratories.

A rapid antimicrobial susceptibility test based on chemiluminescence assay and its application to screening of genotypes in vancomycin-resistant enterococci.

Minimum inhibitory concentrations (MICs) of vancomycin (VCM) and teicoplanin (TEIC) were measured using a novel susceptibility test based on the chemiluminescence assay (CA) method (Rapid-Lumi Eiken; Eiken Chemicals, Tokyo, Japan) against 33 strains in total: 7, 5, and 10 strains of which are VCM-resistant enterococci (VRE) with vanA, vanB, and vanC genes, respectively, and the other 11 strains are vancomycin-susceptible enterococci (VSE). The results were in good accordance with the values determined by the standard broth dilution method approved by the National Committee for Clinical Laboratory Standards (NCCLS): i.e., 88% (29/33) of consistency for VCM and 97% (32/33) for TEIC, respectively. In addition, genotypes in VRE strains (vanA, vanB, vanC-1, and vanC-2/3 genes) were properly estimated from the results of the CA method and the NCCLS interpretive categories, even though the incubation time was very short (2-4 h). In conclusion, it was found that the new method is reliable and rapid to detect VRE strains in clinical laboratories.

Evaluation of a novel automated chemiluminescent assay system for antimicrobial susceptibility testing.

The newly developed Rapid Lumi Eiken/IS60 (RL/IS60) system automatically determines MICs by detecting chemiluminescence produced in the reaction of a chemiluminescent probe and oxygen metabolites from living microorganisms. The present study evaluated this system for accuracy in antimicrobial susceptibility testing. Chemiluminescence intensities after 4 h of cultivation of clinically important strains were plotted against various concentrations of antimicrobial agents, which resulted in curves reflecting the levels of susceptibility. Sixty-percent inhibitory concentrations based on the susceptibility curves agreed with MICs determined by the reference microdilution method. When the MICs of antimicrobial agents for four quality control (QC) strains (Staphylococcus aureus, Enterococcus faecalis, Escherichia coli, and Pseudomonas aeruginosa) were determined by the RL/IS60 system, most (91.1%) of them were within the QC limits proposed by the National Committee for Clinical Laboratory Standards. The system was further assessed for a total of 162 clinical isolates, including E. coli, Citrobacter freundii, Enterobacter cloacae, Klebsiella pneumoniae, Serratia marcescens, Proteus mirabilis, Morganella morganii, P. aeruginosa, Haemophilus influenzae, S. aureus, coagulase-negative staphylococci, Enterococcus faecalis, Enterococcus faecium, and Streptococcus pneumoniae. Overall, there was 90.6% agreement between the RL/IS60 system and the reference microdilution method. Our results suggest that the RL/IS60 system provides rapid and reliable MICs of a variety of antimicrobial agents for clinical isolates as well as QC strains.