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C Shimauchi

Publications and source records attributed to C Shimauchi.

8 recordsLinked to original sources
PubMed2001

Identification of aminoglycoside-modifying enzymes by susceptibility testing: epidemiology of methicillin-resistant Staphylococcus aureus in Japan.

A multiple-primer PCR was used to identify genes encoding aminoglycoside-modifying enzymes in 381 clinical isolates of methicillin-resistant Staphylococcus aureus (MRSA). The technique used three sets of primers delineating specific DNA fragments of the aph(3')-III, ant(4')-I, and aac(6')-aph(2") genes, which influence the MICs of gentamicin, tobramycin, and lividomycin. Isolates with none of the three genes detected were susceptible to all three agents. Isolates with the aph(3')-III gene showed resistance to lividomycin (MIC > 1,024 microg/ml), and those with the ant(4')-I gene were resistant to tobramycin (MIC > or = 8 microg/ml). Isolates with only the aac(6')-aph(2") gene were resistant to gentamicin (MIC > or = 8 microg/ml) and tobramycin in decreasing order; those with both the ant(4')-I and aac(6')-aph(2") genes also were resistant to gentamicin and tobramycin, but in increasing order. Susceptibility testing, then, could detect specific genes. In 381 Japanese MRSA isolates, the ant(4')-I, aac(6')-aph(2"), and aph(3')-III genes were prevalent in 84.5, 61.7, and 8.9%, respectively. Isolates with only the ant(4')-I gene had coagulase type II or III, but isolates with both the ant(4')-I and aac(6')-aph(2") genes included all coagulase types. Most isolates with coagulase type IV or VII carried the aac(6')-aph(2") gene. Of the MRSA isolates with ant(4')-I and/or aac(6')-aph(2") genes, 97% were resistant to aminoglycosides in clinical use, but a new aminoglycoside, arbekacin, had excellent activity against these isolates.

Acetyltransferases↗
PubMed1998

Epidemiologic typing of methicillin-resistant Staphylococcus aureus in neonate intensive care units using pulsed-field gel electrophoresis.

To elucidate the mode of dissemination of methicillin-resistant Staphylococcus aureus (MRSA) in neonate intensive care units (NICUs), a total of 223 isolates from 3 separate hospitals were investigated between 1994 and 1996 by a DNA fingerprinting technique with pulsed-field gel electrophoresis (PFGE). Exoprotein profiles of some strains were also examined using SDS-polyacrylamide gel-electrophoresis (SDS-PAGE) and the assessment of enzyme/toxin production such as coagulase, enterotoxin and TSST-1. Judging from the strain typing data from PFGE results and the epidemiological data, 2 different types of PFGE patterns (A and B) and their subtypes (A', A'' and B') were identified. The A type including A' and A'' (comprising approximately 95% of the isolates) was markedly dominant. Only 5% of the isolates belonged to type B and subtype B'. On the other hand, MRSA isolated from adult patients admitted to the same hospital showed many different PFGE patterns. The results strongly suggested that some strain(s) with specific PFGE pattern(s) is prevalent in NICUs. Furthermore, isolates which expressed the same PFGE pattern did not always express the same SDS-PAGE pattern. There were some isolates with different abilities to produce coagulase, enterotoxin C and toxic-shock syndrome toxin (TSST)-1, and the abilities had no relation with a particular type of PFGE pattern. Therefore, a combination of PFGE analysis and biochemical analyses of coagulase, enterotoxin C and TSST-1 may provide us with more detailed information for the epidemiological study of MRSA in NICUs.

Adult↗
PubMed1998

Why do antimicrobial agents become ineffectual?

Antibiotic resistance has evolved over the past 50 years from a merely microbiological curiosity to a serious medical problem in hospitals all over the world. Resistance has been reported in almost all species of gram-positive and -negative bacteria to various classes of antibiotics including recently developed ones. Bacteria acquire resistance by reducing permeability and intracellular accumulation, by alteration of targets of antibiotic action, and by enzymatic modification of antibiotics. Inappropriate use of an antibiotic selects resistant strains much more frequently. Once resistant bacteria has emerged, the resistance can be transferred to other bacteria by various mechanisms, resulting in multiresistant strains. MRSA is one of the typical multiresistant nosocomial pathogens. A study of the PFGE pattern of endonuclease-digested chromosomal DNA showed that MRSA of a few clones were disseminated among newborns in the NICU of a Japanese hospital. In this regard, it is important to choose appropriate antibiotics and then after some time, to change to other classes to reduce the selection of resistant strains. Since the development of epoch-making new antibiotics is not expected in the near future, it has become very important to use existing antibiotics prudently based on mechanisms of antibiotic action and bacterial resistance. Control of nosocomial infection is also very important to reduce further spread of resistant bacteria.

Cross Infection↗
PubMed1996

Detection of tet(K) and tet(M) in Staphylococcus aureus of Asian countries by the polymerase chain reaction.

This study describes the use of the polymerase chain reaction (PCR) to detect the tet(K) and tet(M) tetracycline resistance genes in Staphylococcus aureus. Primers based on the DNA sequence of the tet(K) and tet(M) genes from S. aureus were used as primers in the PCR assay to detect the presence of genes for resistance to tetracycline and minocycline. Two-hundred and fifteen isolates of S. aureus from Asian countries as Japan, Indonesia, China, Korea and Thailand were examined, and the results confirm that tet(K) specifies resistance to tetracycline but not to minocycline and tet(M) specifies resistance to both tetracycline and minocycline. We observed two different types of clinical isolates of S. aureus strains resistant to minocycline and tetracycline: the first carried only the tet(M) gene, while the second carried both the tet(M) and the tet(K) genes. Almost all of the clinical isolates of S. aureus resistant to minocycline and tetracycline from Indonesia, China and Thailand carried both tet(M) and tet(K) genes, while most of clinical isolates of S. aureuss from Japan and Korea carried only tet(M) gene.

Anti-Bacterial Agents↗
PubMed1994

[Epidemiological survey of methicillin-resistant Staphylococcus aureus isolated from 34 hospitals in Japan].

Eight hundred and seventy-two isolates of clinically significant methicillin-resistant Staphylococcus aureus (MRSA) with their clinical information were obtained between 1992 and 1993 from thirty-four hospitals in Japan. The isolation frequency of MRSA was high in sputum (42.9%), pus (33.1%) and blood (14.0%). Pseudomonas aeruginosa was a major bacterial species in polymicrobial infections with MRSA. Enterobacteriaceae and Candida sp. were also frequently isolated with MRSA. Four different coagulase types were identified. Coagulase type II was found in 85.6% of all MRSA strains tested. The isolation frequencies of coagulase type III, type IV and type VII were 3.1%, 3.6% and 3.2%, respectively. The strains of MRSA contained coagulase type II were prevalent in all geographical areas of Japan, but other coagulase types were limited in western areas of the country. The strains of MRSA were tested for their susceptibility to twelve antimicrobial agents and for production of penicillinase. More than 80% of MRSA strains were highly resistant to methicillin, and were also resistant to macrolide antibiotics and tobramycin. Frequencies of resistance to gentamicin, minocycline or ofloxacin were approximately 60%, 50% or 70%, respectively. But only a small percentage of strains were resistant to arbekacin and all of the MRSA tested were susceptible to vancomycin.

Anti-Bacterial Agents↗
PubMed1994

[Genomic DNA fingerprinting of arbekacin-resistant MRSA by pulsed-field gel electrophoresis].

We surveyed 387 clinical isolates of methicillin-resistant Staphylococcus aureus (MRSA) obtained from 26 hospitals isolated in 1993 to determine whether they became resistant to arbekacin (ABK). Twenty-five ABK-resistant MRSA (6.5%) were isolated from 9 hospitals. Analysis of genomic DNA fingerprinting by pulsed-field gel electrophoresis was used to confirm the classification by resistance patterns, phage typing and other biological characters. After digestion with endonuclease SmaI, two or three types of restriction patterns were found in ABK-resistant MRSA isolated from each hospital. We concluded that ABK-resistant MRSA may spread through nosocomial MRSA infections.

Aminoglycosides↗