Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UMLS:C0276640 (TEM)
 20,729 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The in-vitro activity of SR 44337 was compared with that of other broad-spectrum parenteral cephalosporins, plus imipenem and co-amoxiclav. SR 44337 showed good activity against the Enterobacteriaceae, with MIC90s of less than 0.5 mg/L against all species tested, with the exception of Citrobacter spp. (MIC90 2 mg/L) and Serratia spp. (MIC90 4 mg/L). Of the agents tested, only ceftriaxone showed consistently greater activity against this family of organisms. SR 44337 had higher activity than ceftriaxone against Acinetobacter spp. and Pseudomonas aeruginosa, and was the most active agent tested against Neisseria meningitidis (MIC90 0.004 mg/L). All strains of N. gonorrhoeae, Haemophilus influenzae and the streptococci (excluding the enterococci) were susceptible to less than or equal to 0.25 mg/L of SR 44337, which was also the most active cephalosporin tested against Staphylococcus aureus. SR 44337 was stable to hydrolysis by the TEM-1, SHV-1 and P99 beta-lactamases, and was more stable than ceftriaxone to the K-1 beta-lactamase.
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PMID:In-vitro activity and beta-lactamase stability of SR 44337, a new long acting cephalosporin. 177 54

The NCTC type strains and four clinical isolates of Enterobacter cloacae, Citrobacter freundii, Serratia marcescens, Morganella morganii, Providencia stuartii and Pseudomonas aeruginosa were exposed, in agar, to cefepime at 3, 5, and 10 x MIC and a breakpoint concentration of 16 mg/L. Mutants were selected at a frequency of approximately 10(-8) that had decreased susceptibility to cefepime and cefpirome, and species-dependent resistance to other beta-lactams. Any putative mutant with a greater than four-fold increase in the MIC was examined to determine its beta-lactamase expression and outer membrane protein (Omp) profile. Mutant strains of P. stuartii and M. morganii lacked an Omp of molecular mass similar to that of OmpF, and were cross-resistant to nalidixic acid. Mutant strains of E. cloacae had derepressed class I beta-lactamase production and lacked an Omp corresponding to OmpF, suggesting that in this species both parameters are necessary for decreased susceptibility. Derepressed beta-lactamases purified from mutant strains of E. cloacae, C. freundii and P. stuartii was able to hydrolyse cefepime, but not as quickly as TEM-10.
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PMID:Selection and characterization of cefepime-resistant gram-negative bacteria. 177 70

The in vitro activity of ME-1206, a new aminothiazolyl cephalosporin that can be orally absorbed when converted to an ester, was compared with that of other beta-lactams. ME-1206 inhibited 50% of the Enterobacteriaceae at 2 micrograms/ml, similar to cefotaxime, ceftazidime, and cefixime. It did not inhibit, MIC greater than or equal to 32 micrograms/ml, Enterobacter species or Citrobacter freundii resistant to cefotaxime and ceftazidime, and it was less active than cefotaxime and ceftazidime against Serratia marcescens. Haemophilus influenzae, Neisseria gonorrhoeae, and Moraxella catarrhalis were inhibited by less than or equal to 0.25 micrograms/ml of ME-1206 inhibited hemolytic streptococci groups A, B, C, and G, MIC90 0.06 micrograms/ml, but it did not inhibit enterococci. Pseudomonas aeruginosa and other pseudomonads were resistant to ME-1206. MICs and MBCs of ME-1206 for susceptible species were within a dilution. ME-1206 was not hydrolyzed by TEM-1 or TEM-2, but was hydrolyzed by TEM-3 and TEM-5. ME-1206 was hydrolyzed by beta-lactamases of Morganella, Proteus vulgaris, and K1 of Klebsiella oxytoca, but minimally by the P99 beta-lactamase of Enterobacter cloacae. ME-1206 is comparable in in vitro activity and beta-lactamase stability to many of the current cephalosporins.
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PMID:In vitro activity of a new cephalosporin ME-1206 compared with other agents. 179 56

Class A beta-lactamases are the major cause of bacterial resistance to beta-lactam antibiotics. In these active-site serine hydrolases, glutamic acid 166 has been hypothesized to act as a general acid-base catalyst. Replacing this residue by tyrosine in TEM-1 beta-lactamase yields an enzyme the activity of which is substantially lowered and strongly dependent on pH, thus confirming the alleged role of Glu166 in catalysis. This substitution also resulted in a spectacular change in substrate profile, the mutant enzyme being more active on cephalosporins than on penicillins. In fact, the E166Y enzyme behaves much like a class C enzyme, with high affinity and low hydrolytic activity towards second and third generation cephalosporins. Glu166 therefore seems to play a major part in defining the substrate profile of class A beta-lactamases.
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PMID:Site-directed mutagenesis on TEM-1 beta-lactamase: role of Glu166 in catalysis and substrate binding. 179 3

The susceptibility of 455 Escherichia coli blood culture isolate to piperacillin was tested with the disk diffusion test. The presence of different beta-lactamase genes in these strains was also studied using DNA hybridization. Of the TEM beta-lactamase producing isolates, 64% (61/95) were interpreted as intermediately susceptible to piperacillin. Because piperacillin is hydrolyzed by TEM-type beta-lactamases, we suggest that the intermediate susceptibility category should be reduced or omitted in testing piperacillin susceptibility of Escherichia coli isolates.
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PMID:Problems in interpretation of piperacillin susceptibility of TEM-1 producing Escherichia coli in the disk diffusion test. 180 98

From 1983 to 1989, 520 Escherichia coli blood culture pathogens were isolated from two hospitals in Turku, Finland. Ampicillin resistance (MIC greater than or equal to 16 micrograms/ml) of these isolates increased from 33% in 1983 to 66% in 1987, but decreased to 38-49% in 1988-1989. Occurrence of TEM-1 beta-lactamase producing isolates increased only slightly from 14% in 1983 to 25% in 1989 among all Escherichia coli strains studied. Strains with ampicillin MIC values of 16 micrograms/ml and 32 micrograms/ml were mostly responsible for the increase in resistance. Among these isolates, TEM-1 or any other of the well known plasmid-mediated beta-lactamases were not found by hybridization or isoelectric focusing.
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PMID:Analysis of beta-lactamase production in ampicillin-resistant Escherichia coli isolated from blood cultures 1983-1989. 180 99

An isolate of Serratia marcescens that produced both an inducible chromosomal and a plasmid-mediated TEM-1 beta-lactamase was resistant to ampicillin and amoxicillin and also demonstrated decreased susceptibility to extended-spectrum beta-lactam antibiotics (ESBAs). Clavulanic acid did not lower the MICs of the ESBAs, but it decreased the MICs of the penicillins. The TEM-1-producing plasmid was transferred to a more susceptible S. marcescens strain that produced a well-characterized inducible chromosomal beta-lactamase. The MICs of the ESBAs remained at a low level for the transconjugant. Ampicillin and amoxicillin which were good substrates for the plasmid-mediated enzyme, were not well hydrolyzed by the chromosomal enzymes; the ESBAs were hydrolyzed slowly by all the enzymes. When each of the S. marcescens strains was grown with these beta-lactam antibiotics, at least modest increases in chromosomal beta-lactamase activity were observed. When organisms were grown in the presence of clavulanic acid and an ESBA, no enhanced induction was observed. The increases in the MICs of the ESBAs observed for the initial clinical isolate may have been due to a combination of low inducibility, slow hydrolysis, and differences in permeability between the S. marcescens isolates. When clavulanic acid and a penicillin were added to strains that produced both a plasmid-mediated TEM and a chromosomal beta-lactamase, much higher levels of chromosomal beta-lactamase activity were present than were observed in cultures induced by the penicillin alone. This was due to the higher levels of penicillin that were available for induction as a result of inhibition of the TEM enzyme by clavulanate.
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PMID:Effect of clavulanic acid on activity of beta-lactam antibiotics in Serratia marcescens isolates producing both a TEM beta-lactamase and a chromosomal cephalosporinase. 180 92

The extended-spectrum beta-lactamases are believed to arise by mutations which alter the configuration around the active site of TEM- and SHV-type enzymes so as to increase their efficiency with otherwise nonhydrolyzable cephalosporins and monobactams. This hypothesis predicts that the genes for these new enzymes should be found on the same wide variety of plasmids that encode TEM-1, TEM-2, and SHV-1 beta-lactamases and that at least some of them should be mediated by transposons. Fifteen plasmids, each encoding an extended-spectrum beta-lactamase, were examined. Unlike the average TEM plasmid, all were large, ranging in size from 80 to 300 kb. All determined resistance to multiple antimicrobial agents, ranging from 5 to 11, and some conferred resistance to heavy metals and UV radiation as well. The plasmids belonged to a limited number of incompatibility (Inc) groups, including IncC, IncFI, IncHI2, and IncM. Because most of the mutations giving rise to extended-spectrum activity are G.C----A.T transitions and some of the mutant genes have as many as four base substitutions, a plasmid-determined mutator gene was searched for, but no such property was found. Several techniques were used to detect transposition of the extended-spectrum beta-lactamase genes, but a mobile genetic element could not be demonstrated even though eight of the plasmids hybridized with a DNA probe derived from the tnpR gene of Tn3. The genesis of extended-spectrum beta-lactamases may not be as simple as has been supposed.
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PMID:Properties of plasmids responsible for production of extended-spectrum beta-lactamases. 184 7

Two isolates of Klebsiella pneumoniae possessing both TEM-1 and SHV-2 beta-lactamases were isolated from patients at the Cleveland Clinic in 1988. The beta-lactamases were discriminated and identified by using substrate hydrolysis data and an isoelectric focusing procedure in which the gel was overlaid with beta-lactamase inhibitors.
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PMID:High-level resistance to cefotaxime and ceftazidime in Klebsiella pneumoniae isolates from Cleveland, Ohio. 185 55

Salmonella kedougou BM2659 was isolated from the stools and a blood culture of a patient and Klebsiella pneumoniae BM2657 and S. kedougou BM2658 were isolated later from the stools of the same patient. Strains BM2657 and BM2658 had identical resistance phenotypes, to beta-lactams, aminoglycosides and tetracycline, due to the presence of the same genes, blaT, aacA4 and tetC, respectively. Oligotyping indicating that beta-lactam resistance in these strains was encoded by blaT-3 and synthesis of TEM-3 was confirmed by isoelectric focusing. In BM2657 and BM2658, the resistance characters were located on Inc7 or M self-transferable plasmids with indistinguishable EcoRI and HindIII restriction patterns. Southern hybridization of plasmid DNA of these strains with probes pCFFO4, the prototype plasmid encoding TEM-3, genes blaT, aacA4 and tetC gave identical patterns. S. kedougou BM2658 and BM2659 had identical biotypes and serotypes but BM2659 was susceptible to all the study antibiotics. These observations suggest possible transfer, in the digestive tract, of a plasmid encoding TEM-3 beta-lactamase from K. pneumoniae BM2657 to S. kedougou BM2659.
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PMID:Possible in-vivo transfer of beta-lactamase TEM-3 from Klebsiella pneumoniae to Salmonella kedougou. 185 22


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