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Biomedical subjects

S Mitsuhashi

Publications and source records attributed to S Mitsuhashi.

At least 181 records · Page 10Linked to original sources
PubMed1984

Inactivation of cephamycins by various beta-lactamases from gram-negative bacteria.

The enzymic inactivation of cephamycins, i.e. cefoxitin, cefmetazole, cefotetan and cefbuperazone, was investigated by means of bioassay, high pressure liquid chromatography (HPLC) and spectrophotometric analysis using three types of cephalosporinase (CSase, RICHMOND type Ia, Ib and Ic) and one penicillinase (PCase, TEM type). These four cephamycins were not inactivated by Ic CSase and TEM type PCase or producers of these enzymes. However, the inactivation of cefmetazole and cefoxitin was noted when they were incubated in the cultures of CSase (Ia and Ib)-producers or incubated with a large amount of these purified enzymes although the inactivation of cefbuperazone was not noted. HPLC of culture fluid or enzyme solution which contained cefmetazole or cefoxitin and were incubated at 37 degrees C showed that metabolites of cefmetazole or cefoxitin appeared as the drug disappeared. In addition, the appearance of metabolites corresponded to the loss of the drug's bioactivities and the absorption of iodine. UV and IR spectra of cefmetazole which were taken after incubation with the purified CSase showed the cleavage of the beta-lactam ring.

Bacteria↗
PubMed1983

pMS76, a plasmid capable of amplification by treatment with chloramphenicol.

pMS76 is a nonconjugative, 5.54-megadalton plasmid. This plasmid is present in Escherichia coli K12 cells at about 20 copies per chromosome. In addition, the pMS76 plasmid can be mobilized by conjugative plasmids and it shares a number of other properties with the amplifiable ColE1 plasmid, including the ability to amplify copy number in the presence of chloramphenicol. However, pMS76 is compatible with ColE1-like replicons, pBR313, and with other multicopy plasmids, RSF1030 and pACYC184. Also the replication of pMS76 is rifampicin sensitive and requires DNA polymerase 1.

Ampicillin↗
PubMed1983

In-vitro and in-vivo antibacterial activity of imipenem against clinical isolates of bacteria.

Imipenem, a derivative of thienamycin, a carbapenem antibiotic, has a broad spectrum of activity against aerobic (Gram-positive and Gram-negative) and anaerobic bacteria. It is quite stable to all tested beta-lactamases produced by various species of bacteria isolated from clinical specimens, whether plasmid or chromosomally mediated. One exception is its hydrolysis by the beta-lactamase produced by Pseudomonas maltophilia which is thus usually resistant to imipenem. Imipenem was found to be hydrolysed by renal dehydropeptidase-I residing on the luminal surface of the renal tubular epithelium. A dehydropeptidase-I inhibitor, cilastatin (MK-0791) was developed with specific inhibitory activity toward the renal dehydropeptidase-I and showed detectable effects in humans.

Animals↗
PubMed1983

Drug resistance and R plasmids in Escherichia coli strains isolated from broilers.

In 1978, 1,021 Escherichia coli strains were isolated from 105 field broilers (F) and 1,058 strains from 106 broilers in a zootechnical experiment station (Z), and their drug-resistance patterns and the presence of conjugative R plasmids were compared. The resistance markers examined were tetracycline (TC), chloramphenicol (CM), streptomycin (SM), sulfonamides (SA), kanamycin (KM), and ampicillin (APC). The populations of individuals that excreted resistant strains were 100% in F and 58% in Z. Frequencies of isolation of drug-resistant strains among the total isolates were 93% in F and 36% in Z, indicating that the resistant strains are a rather high proportion of the intestinal flora in F but are slightly less prevalent in Z. The resistance pattern to (TC.SM.SA.KM) was seen at the highest frequency in both groups. Conjugative R plasmids were demonstrated more frequently in field broilers (F). The results reflect the wide use of antibiotics in the livestock industry, resulting in the appearance of drug-resistant strains mostly due to the presence of R plasmids.

Animals↗
PubMed1983

Conjugal transferability of multiple resistance in Shigella strains.

Shigella strains isolated in Japan between 1971 and 1979 were surveyed for drug resistance and distribution of R plasmids. Of 2,510 strains, 89.3% were resistant to either one or various combinations of four drugs, tetracycline, chloramphenicol, streptomycin, and sulfanilamide. About 66% of the Shigella isolates were quadruply resistant. The frequency of isolation of R plasmids from quadruply resistant Shigella strains was the highest when compared with other strains resistant to various combinations of the four drugs. The conjugal transferability of 204 quadruply resistant strains isolated between 1977 and 1979 was tested by various mixed-culture methods. Among the total strains examined, 70.6% carried transferable resistance when tested by the conventional broth culture method, 90.2% transferred their resistance when, in addition the replica-plating method was used and 97.5% could transfer their resistance when the membrane filter method was also used. Although the remaining five strains could not transfer their resistance by any of the mixed culture methods, the drug resistance of four of the five strains was mobilized by the concomitant presence of F-tet or T-kan plasmid. These results indicate that almost all of the quadruple resistance in Shigella isolates was mediated by plasmid.

Conjugation, Genetic↗
PubMed1983

Drug resistance and conjugative R plasmids in fecal Escherichia coli strains isolated from healthy younger animals (chickens, piglets, calves) and children.

A total of 11,777 Escherichia coli strains were isolated from 90 chickens, 103 piglets, 96 calves, and 104 children in 1979 in Gunma Prefecture and tested for drug resistance and the presence of conjugative R plasmids. The percentages of individuals that excreted drug-resistant strains were: chickens, 100%; piglets, 99%; calves, 100%; and children, 64%. The frequency of isolation of drug-resistant strains among the total isolates was: chickens, 98%; piglets, 93%; calves, 94%; and children, 41%. Frequency of isolation of R plasmids among the strains tested was: chickens, 48%; piglets, 33%; calves, 38%; and children, 10%. Resistance patterns of the strains isolated most frequently among the four groups were tetracycline (TC), sulfonamides (SA) in single resistance, TC.SA in double resistance, TC.streptomycin (SM).SA in triple resistance and TC.SM.SA. kanamycin (KM) in quadruple resistance. R plasmids were isolated frequently from animals (over 33%) but infrequently from children (about 10%). The high frequency of isolation of drug-resistant strains and R plasmids from animals was caused by the heavy use of chemicals in the period of growth of younger animals.

Age Factors↗
PubMed1983

Incompatibility group K plasmids in bacteria isolated from a urinary tract infection.

Citrobacter freundii and Klebsiella pneumoniae were concurrently isolated from a patient with a urinary tract infection. Transferable drug resistant plasmids were isolated from both strains, pMS434 and pMS435. These plasmids belonged to incompatibility group K and both carried genes governing resistance to various aminoglycoside antibiotics, i.e., kanamycin, gentamicin C complex, streptomycin, and 3',4'-dideoxykanamycin B, in addition to those governing resistance to sulfanilamide and ampicillin. They inactivated kanamycin, gentamicin C complex and 3',4'-dideoxykanamycin by adenylylation and kanamycin by phosphorylation. Electron microscopic observations disclosed that the molecular weights of the plasmids were about 67.8 megadaltons. These results indicated the similarity in genetic constitution of the two plasmids. This was the second isolation of incompatibility group K plasmids, following that reported by Hedges and Datta (Nature 234: 220-221, 1971).

Aminoglycosides↗
PubMed1983

Tn2011, a new transposon encoding oxacillin-hydrolyzing beta-lactamase.

The type II penicillinase (oxacillin-hydrolyzing beta-lactamase, OXA-1) gene on plasmid Rms213 was transposed to various plasmids or to the host chromosome. The transposon bearing this gene, designated Tn2011, conferred resistance to ampicillin, streptomycin, sulfonamide, and mercuric chloride. By restriction endonuclease digestion and agarose gel electrophoresis, the molecular weight of Tn2011 was estimated to be 12.5 X 10(6). The transposition frequency of Tn2011 was about 10(-4) to 10(-5). The activity of type II penicillinase is related to the copy number of the replicon bearing Tn2011.

Ampicillin↗
PubMed1983

In vitro and in vivo antibacterial activity of AT-2266.

AT-2266 [1-ethyl-6-fluoro-1,4-dihydro-4-oxo-7-(1-piperazinyl)-1,8-naphthyridine-3-carbo xylic acid] showed a broad spectrum of antibacterial activity against gram-positive and gram-negative microorganisms, including Pseudomonas aeruginosa. The in vitro antibacterial activity of AT-2266 was in general comparable to that of norfloxacin, but much higher than that of pipemidic or nalidixic acid. The 90% minimal inhibitory concentrations (MIC90s) of AT-2266 for P. aeruginosa resistant to gentamicin (MIC range, 25 to greater than 200 microgram/ml) and Enterobacteriaceae resistant to nalidixic acid (25 to greater than 1,600 micrograms/ml) were 3.13 and 12.5 micrograms/ml, respectively. The to nalidixic acid (25 to 1,600 micrograms/ml) were 3.13 and 12.5 micrograms/ml, respectively. The MICs of AT-2266 were only slightly affected by the addition of horse serum or sodium cholate, by the pH of the medium, and by inoculum size. AT-2266 was sodium cholate, by the pH of the medium, and by inoculum size. AT-2266 was bactericidal at concentrations near its MIC value. The 50% effective doses of AT-2266 after oral administration against systemic infections in mice were about 1/2 those of norfloxacin, about 1/10 those of pipemidic acid, and between 1/20 and 1/40 those of nalidixic acid.

Animals↗
PubMed1983

Efficacy of BRL 25000 against Serratia marcescens, Enterobacter cloacae, and Citrobacter freundii in urinary tract infections.

Synergism between amoxicillin and clavulanic acid was not expected against cephalosporinase-producing bacterial strains because clavulanic acid has little inhibitory action on cephalosporinases. However, in a clinical trial of BRL 25000 (amoxicillin-clavulanic acid), excellent results were obtained in complicated urinary tract infections caused by Serratia marcescens, Enterobacter cloacae, and Citrobacter freundii strains which produced cephalosporinase and were highly resistant to amoxicillin alone. The good clinical efficacy of BRL 25000 in such urinary tract infections was probably due to the fact that the urinary concentration of clavulanic acid was higher than its minimal inhibitory concentrations for these strains.

Amoxicillin↗
PubMed1983

Properties of novel beta-lactamase produced by Bacteroides fragilis.

Bacteroides fragilis strains were isolated from clinical specimens. B. fragilis G-237 was highly resistant to beta-lactam antibiotics due to beta-lactamase production. The purified enzyme from this strain gave a single protein band on polyacrylamide gel electrophoresis. The isoelectric point was 4.8, and the molecular weight was estimated to be 26,000 by sodium dodecyl sulfate-polyacrylamide gel electrophoresis. The enzyme activity was inhibited by p-chloromercuribenzoate and iodine but not by clavulanic acid or sulbactam. The purified enzyme showed a unique substrate profile by hydrolyzing at a high rate most of the cephalosporins, including cephamycin derivatives, penicillins, and imipenem (formerly imipemide, N-formimidoyl thienamycin, or MK 0787).

Bacteroides fragilis↗
PubMed1983

Mapping of the gene specifying aminoglycoside 3'-phosphotransferase II on the Pseudomonas aeruginosa chromosome.

We examined the aminoglycoside inactivation enzymes in Pseudomonas aeruginosa strains, seven clinical isolates and seven laboratory strains without plasmids. All strains were found to possess the enzyme aminoglycoside 3'-phosphotransferase II [APH(3')-II]. We isolated an APH(3')-II-deficient mutant from a PAO strain by mutagenesis with N-methyl-N'-nitro-N-nitrosoguanidine. By plasmid (FP5 or R68.45)-mediated conjugation, we determined the locus of the gene specifying the APH(3')-II between trp-6 and pro-82 on the PAO chromosome and designated this gene aphA. It was concluded that the intrinsic resistance of P. aeruginosa to kanamycins, neomycins, paromomycins, ribostamycin, and butirosins was due to this newly determined gene.

Chromosome Mapping↗
PubMed1983

Induction of cephalosporinase production by various penicillins in enterobacteriaceae.

The inducer activity of seven penicillins for cephalosporinase (CSase) production and their antibacterial activity against CSase-producing strains were studied using clinical isolates of Proteus morganii, P. rettgeri, P. vulgaris, Enterobacter cloacae, and Serratia marcescens. Piperacillin, apalcillin, and methicillin showed rather low inducer activity for CSase production in all strains tested. On the other hand, ampicillin, carbenicillin, and sulbenicillin showed high inducer activity for CSase production. Piperacillin, apalcillin, and ampicillin were less stable to CSases than were carbenicillin, sulbenicillin, and methicillin, but much more stable than benzylpenicillin. In the growing culture of CSase-producing strains, piperacillin and apalcillin were rather stable. Against CSase-producing strains, piperacillin and apalcillin were more active than other penicillins tested.

Cephalosporinase↗
PubMed1983

Characterization of cephalosporinases from Bacteroides fragilis, Bacteroides thetaiotaomicron and Bacteroides vulgatus.

The susceptibility of 80 Bacteroides fragilis group strains isolated from clinical specimens to beta-lactam antibiotics was investigated by agar dilution method. Twenty strains showed high resistance to the antibiotics. The resistance level of the isolates to cephaloridine was related to the amount of beta-lactamase activity (cephalosporinase; CSase) produced. B. fragilis GN-11477, B. thetaiotaomicron GN11478 and B. vulgatus GN11479 were selected from among the CSase producing strains, and the enzymes were purified about 300-fold by affinity chromatography employed ampicillin as ligand bound to activated CH Sepharose 4B. The enzyme preparations gave a single protein band on polyacrylamide gel electrophoresis. The molecular weights of the three enzymes were estimated to be approximately 32,000 and their isoelectric points were 5.2, 4.9 and 4.5, respectively. The optimal pH and the optimal temperature of the enzymes were 7.2 and 37 degrees C, respectively. The enzyme activities were inhibited by iodine, some divalent ions, p-chloromercuribenzoate, clavulanic acid, cephamycin derivatives and cloxacillin. The enzymes showed hydrolytic activity against cephaloridine, cephalothin, cefazolin, cefuroxime and also newly introduced cephalosporins such as cefotaxime, cefoperazone and cefmenoxime. Each mouse antisera obtained against the purified enzymes showed cross-reactions with its each enzyme and others in neutralization test.

Ampicillin↗