[Development and Evaluation of Screening Culture Medium for Detection of Drug-Resistant Gram Negative Rods Containing Stealth Type CPE].

There is a report that an infection by medicine resistant bacteria will be the number one cause of death in 2050 according to the recommendation of WHO, and the CPE (carbapenem-producing Enterobacteriaceae) infection is regarded as a problem in particular. When detecting CPE, it is important how to detect stealth type CPE sensitive to carbapenem series medicines. So we used the 2 types of screening culture medium, "KBM" CRE-JU culture medium (CRE-JU culture medium) and the FRPM culture medium, and tried to detect drug-resistant gram-negative bacilli such as CPE, stealth type CPE, ESBL-producing bacteria, and excess AmpC-producing bacteria (AmpC-producing bacteria), etc. in combination of this culture mediums. As a result, CRE-JU culture medium showed a difference in the growth of CPE depending on the amount of inoculated bacteria while ß-lactamase non-producing strain and other strains except for high concentration ESBL-producing bacteria and AmpC-producing bacteria were un-growing. Most of the CRE, stealth type CPE, ESBL-producing bacteria and AmpC-producing bacteria grew in the FRPM culture medium while most of the ß-lactamase non-producing strains with a MIC value of meropenem (MEPM) of 2 µg/mL or less were un-growing. From these results, it was suggested that when a strain grown on CRE-JU and FRPM culture mediums, it could be distinguished as CPE, and when strains grown on FRPM culture medium which were un-grown on CRE-JU culture medium, it could be distinguished as drug-resistant bacteria such as stealth type CPE, ESBL-producing bacteria, and AmpC-producing bacteria. When strains not grown on CRE-JU and FRPM culture mediums, it could be distinguished as sensitive.

[Clinical significance on MicroScan Rapid plus series using various antibiotic-resistant bacteria].

MicroScan Rapid plus Neg II Series and MicroScan Rapid plus Pos Series by Siemens Healthcare Diagnostics K.K. are the panels which enable to measure identification and antimicrobial susceptibility testing quickly and we have confirmed that it is useful for detecting drug resistance bacteria. As the identification result of comparing Rapid plus series with the current panel by using 143 strains of various drug resistance bacteria, Gram positive cocci was 87. 7%, glucose fermenter was 100% and glucose non-fermenter was 77.3 in Gram negative bacilli. On the evaluation of antimicrobial susceptibility testing, Rapid plus series, in comparison with the current panel, confirmed the lower tendency of MIC value on some drugs, but it basically presented the good concordance rate. In terms of the reporting time of antimicrobial agent, non-fermenter or MRCNS reported the result as needed after 8 hours and it took a little longer time for the report of antimicrobial agent. On the other hand, 80% or higher of antimicrobial agent on panel was reported for intestinal bacteria in 4.5 hours and for MRSA in 6.5 hours. It enabled to report the testing result on the same day. Due to the results above, Rapid plus series was highly valued on the usability, such as the early detection of drug resistance bacteria and the selection of therapeutic agents.

[Rapid detection of Vibrio vulnificus using a loop-mediated isothermal amplification method].

Vibrio vulnificus is found in marine waters near the coast around the world. Infection with this gram-negative rod, via ingestion of raw seafood or via a skin wound following contact with contaminated estuarine or marine water, can cause necrotizing fasciitis and sepsis. Most of patients with Vibrio vulnificus infection have underlying liver dysfunction or diabetes mellitus. Due to the high mortality and short latent periods, control of this infection depends on early identification of the bacterial species and prompt initiation of intensive care. Accordingly, the development of a technique that can identify this microbe quickly and accurately is of great importance. Loop-mediated isothermal amplification (LAMP) is a novel nucleic acid amplification method to detect specific genes with rapidity and high sensitivity. In this study, we developed LAMP for the detection of Vibrio vulnificus. Using 28 Vibrio vulnificus strains and 53 other bacterial strains, we confirmed the high specificity of this method. Moreover, our LAMP method also showed high sensitivity, with a minimum detection level of one colony-forming unit per test. Furthermore, we developed simplified and conventional pretreatments for the method using experimental animal models. All of these attempts have lod to our non being able to detect Vibrio vulnificus within 1 hour.

[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.