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Query: HUMANGGP:008114 (TEM)
 20,717 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The effects of therapeutic concentrations of ampicillin on non-beta-lactamase and beta-lactamase producing strains of Neisseria gonorrhoeae were studied. A small but significant fraction of bacteria in a gonococcal population was found to respond in a bacteriostatic rather than a bactericidal way upon ampicillin treatment. In agreement with this was the finding of morphologically unaltered cells in the scanning electron microscope after ampicillin exposure. Ampicillin treatment of beta-lactamase producing gonococci caused a significant release of the enzyme into the surrounding growth media. However, initially all beta-lactamase activity was cellbound. The rate of initial ampicillin hydrolysis was much higher in intact cells of N. gonorrhoeae (TEM-1) than in cells of Escherichia coli K-12 (TEM-1). This suggests that the diffusion rate of ampicillin is much higher in the former organism. The viability of gonococci (TEM-1) was unlike E. coli (TEM-1) affected by low concentrations of ampicillin. However, after complete hydrolysis of ampicillin, viable gonococci (probably bacteriostatic reacting cells) were able to initiate new growth. This heterogeneity of the cell population to penicillin killing is probably one reason why beta-lactamase producing gonococci despite a rather low MIC-value to ampicillin cause infections that are not susceptible to therapy by this agent.
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PMID:Effects of low ampicillin concentrations on penicillin sensitive and beta-lactamase producing strains of Neisseria gonorrhoeae. 11 31

The efficacy of tazobactam, a beta-lactamase inhibitor, in combination with piperacillin, was studied in vitro and in rabbit experimental endocarditis due to a Klebsiella pneumoniae strain (KpR) producing an extended-spectrum beta-lactamase, TEM-3, or its nonproducing variant (KpS). In vitro, piperacillin was active against KpS (MIC = 4 micrograms/ml, MBC = 8 micrograms/ml with 10(7)-CFU/ml inoculum) but not against KpR (MIC = MBC = 256 micrograms/ml). Tazobactam (1 microgram/ml) restored the activity of piperacillin against KpR (MIC = 2 micrograms/ml, MBC = 4 micrograms/ml). Gentamicin was active against both strains (MIC = 0.25 and 0.5 micrograms/ml for KpS and KpR, respectively). The piperacillin-tazobactam-gentamicin combination was synergistic in vitro. The piperacillin/tazobactam ratio in plasma and in vegetations was always lower than the 4/1 injected dose ratio. In vivo, piperacillin (300 mg/kg of body weight four times a day [QID]) was active against KpS but not against KpR. Tazobactam (75 mg/kg QID) was able to restore the in vivo effect of piperacillin (300 mg/kg QID) against KpR (-3.0 log10 CFU/g of vegetation versus that of controls). Gentamicin (4 mg/kg twice a day [BID]) was active against both strains. Compared with controls, the combination of gentamicin plus piperacillin against KpS (-5.6 log10 CFU/g of vegetation), and the gentamicin-piperacillin-tazobactam combination against KpR (-4.4 log10 CFU/g of vegetation) achieved the greatest decrease in bacterial counts in vegetations and were the only regimens that significantly increased the proportion of sterile vegetations. It is concluded that (i) tazobactam was able to restore the effect of piperacillin against a TEM-3 extended-spectrum Beta-lactamase-producing strain of K. pneumoniae, both in vitro and in a severe experimental infection with high inoculum, when used in a 4/1 piperacillin/tazobactam dose ratio; (ii) gentamicin alone was effective because of the high peak/MBC ratio in plasma; (iii) piperacillin-tazobactam-gentamicin, probably because of the effect of gentamicin in reducing bacterial inoculum in vivo, as stressed by the results obtained by piperacillin-gentamicin against KpS, may be the most effective regimen against KpR.
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PMID:Piperacillin, tazobactam, and gentamicin alone or combined in an endocarditis model of infection by a TEM-3-producing strain of Klebsiella pneumoniae or its susceptible variant. 132 34

HR 916B is a new orally absorbed cephalosporin. In tests its active metabolite, RU29246, inhibited Streptococcus pyogenes, Streptococcus agalactiae and Streptococcus pneumoniae at less than or equal to 0.12 micrograms/ml, which is similar to the antibacterial activity of cefuroxime, and was more active than cefaclor. It was also more active (MIC 2 micrograms/ml) than cefixime, cefuroxime, cefaclor and cefotaxime against staphylococci. RU29246 inhibited Escherichia coli, Klebsiella pneumoniae, Citrobacter diversus, Klebsiella oxytoca, Proteus mirabilis, Providencia stuartii and Salmonella spp. at less than or equal to 1 microgram/ml, thus being more active than cefuroxime and cefaclor, but was less active than cefixime and cefotaxime. It did not inhibit Pseudomonas aeruginosa and other Pseudomonas spp., Enterobacter spp., Serratia marcescens or Bacteroides fragilis. RU29246 was not hydrolyzed by TEM-1, Staphylococcus aureus TEM-2 or Moraxella catarrhalis beta-lactamases, but was hydrolyzed by TEM-3 and the chromosomal beta-lactamases of Proteus vulgaris and Morganella morganii. Plasmid and chromosomal beta-lactamases were inhibited by RU29246.
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PMID:Comparative in vitro activity and beta-lactamase stability of RU29246, the active metabolite of HR916B. 139 79

The affinity of meropenem for various known types of beta-lactamases and its stability to them were tested in comparison with other beta-lactams, including imipenem. Meropenem exhibited a marked stability to all beta-lactamases tested and was only hydrolyzed by Xanthomonas maltophilia beta-lactamase, as were other beta-lactams. This was responsible for the potent antibacterial activities of meropenem against beta-lactamase-producing strains. Meropenem and imipenem had almost the same, relatively high affinity for beta-lactamases; however, they had a lower affinity than clavulanic acid for penicillin beta-lactamases and cefoxitin for cephalosporin beta-lactamases. Meropenem also had higher beta-lactamase inhibitory activity than imipenem. Meropenem inhibited type III (TEM-1), Ia Citrobacter freundii and Ic Proteus vulgaris beta-lactamases in a progressive manner. Meropenem was thought to be a potent inhibitor of various beta-lactamase because of its ability to form stable enzyme-meropenem acyl-complexes. Meropenem generally exhibited a lower induction potential than imipenem against five clinical isolates of C. freundii, Enterobacter cloacae and Pseudomonas aeruginosa, but its induction potential was higher than that of ceftazidime. Meropenem induced beta-lactamases at concentrations above the MIC.
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PMID:Beta-lactamase stability and inhibitory activity of meropenem combined with a potent antibacterial activity. 147 60

Ten clinical isolates and the type strain (H37Rv) of Mycobacterium tuberculosis were shown to produce an intracellular beta-lactamase. Crude enzyme preparations were extracted from acetone cell powders by grinding with zirconium beads in 0.133 M glycine with 1.0% Triton X-100. The enzymes had identical patterns on isoelectric focusing, with two major bands at isoelectric points of 4.9 and 5.1. The beta-lactamase was highly susceptible to the new beta-lactamase inhibitor BRL 42715, with an I50 of 0.0001 microgram/ml. The enzyme was also susceptible to clavulanic acid with an I50 (0.05 microgram/ml), which was similar to the value for the common bacterial beta-lactamase TEM-1 (0.01 microgram/ml). The latter result is consistent with previous MIC studies with M. tuberculosis, which have shown synergy between clavulanic acid and amoxicillin. BRL 42715 and clavulanic acid were more active than sulbactam, tazobactam, and cloxacillin. These studies support the potential value of penicillin/clavulanic acid and penicillin/BRL 42715 combinations in the treatment of tuberculosis.
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PMID:beta-Lactamase inhibitors and the inducibility of the beta-lactamase of Mycobacterium tuberculosis. 154 47

Ro 09-1227 is a novel 7-position catechol-substituted parenteral cephalosporin that also has a 3-position radical similar to previously described cephems. The Ro 09-1227 spectrum was slightly wider than that of ceftazidime against members of the family Enterobacteriaceae tested, principally because of greater activity against species producing Richmond-Sykes type I beta-lactamases. Ro 09-1227 was also more active than ceftazidime against some strains producing extended-spectrum plasmid-encoded beta-lactamases, such as TEM-3, -4, -5, -6, -7, and -9, SHV-2 and -3, and CAZ-2. Most strains of Pseudomonas aeruginosa, Xanthomonas maltophilia, and Acinetobacter spp. were also more susceptible to Ro 09-1227 than cefotaxime, ceftriaxone, cefoperazone, and ceftazidime. Haemophilus influenzae (MIC for 90% of strains tested [MIC90], 0.5 micrograms/ml), Neisseria gonorrhoeae (MIC90, 0.015 micrograms/ml), and Moraxella (Branhamella) catarrhalis (MIC90, 0.5 micrograms/ml) were also Ro 09-1227 susceptible. Ro 09-1227 activity against important gram-positive cocci was most comparable to that of ceftazidime. Bacteroides fragilis (MIC90, greater than 32 micrograms/ml) and the enterococci (MIC90, greater than 32 micrograms/ml) were resistant to Ro 09-1227. These in vitro results indicate that this catechol-substituted cephalosporin may be useful as an empiric agent, especially for some isolates resistant to currently available broad-spectrum cephalosporins.
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PMID:In vitro evaluation of Ro 09-1227, a novel catechol-substituted cephalosporin. 159 Jun 95

We report the isolation of a clinical isolate of Klebsiella pneumoniae that showed resistance to ceftazidime (MIC: 8 micrograms/ml), susceptibility to aztreonam (MIC: 2 micrograms/ml) and cefotaxime (MIC: 0.015 micrograms/ml). A synergistic effect between clavulanic acid and ceftazidime or aztreonam against this strain was also observed. The strain hyperproduced SHV-1 penicillinase (990 U/g) which is encoded by a self-transferrable plasmid of at least 150 kb. That the ceftazidime-resistance phenotype could be due to hyperproduction of SHV-1 penicillinase is supported by the study of a spontaneous ceftazidime-resistant mutant in vitro obtained from an Escherichia coli strain containing plasmid p453 encoding the SHV-1. Indeed, this mutant hyperproducing SHV-1 (2200 U/g) was resistant to ceftazidime (MIC: 16 micrograms/ml) and aztreonam (MIC: 8 micrograms/ml) but susceptible to cefotaxime (MIC: 0.03 ng/ml). Clavulanic acid showed a synergistic effect when associated with ceftazidime or aztreonam. In contrast, the hyperproduction of TEM-1 (790 U/g) did not confer a ceftazidime- and aztreonam-resistant phenotype while hyperproduction of both TEM-1 and SHV-1 increased the resistance to amoxycillin/clavulanic acid and to cephalothin.
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PMID:Does high level production of SHV-type penicillinase confer resistance to ceftazidime in Enterobacteriaceae? 162 15

Strains of Escherichia coli (N = 124) and Proteus mirabilis (N = 29) harboring known beta-lactamases were analyzed as to their susceptibility to ampicillin, amoxicillin, and piperacillin alone and in combination with sulbactam, clavulanate, and tazobactam. With TEM 1-producing E. coli, a correlation between specific beta-lactamase activity and the MIC of piperacillin and ampicillin-sulbactam was observed. These strains also showed significant differences in susceptibilities to the various combinations, suggesting that, at least in strains resistant to one combination, several beta-lactam/beta-lactamase inhibitor combinations should be tested in the laboratory. All combinations tested enhanced the activity of the beta-lactam towards TEM 1-producing E. coli, piperacillin-tazobactam being the most active. The drugs were less active to OXA 1 enzymes; solely with piperacillin-tazobactam 90% of strains were within the therapeutic range of the drug. Sulbactam acted synergistically to chromosomally encoded beta-lactamases, whereas amoxicillin-clavulanate was inactive. Piperacillin and piperacillin-tazobactam inhibited all strains producing chromosomally encoded beta-lactamases at concentrations within the therapeutic range of the drugs. In contrast, TEM 2 of P. mirabilis was not sensitive to ampicillin-sulbactam, but to the other combinations; here again piperacillin-tazobactam was the most active.
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PMID:Comparative in vitro activities of amoxicillin-clavulanate, ampicillin-sulbactam and piperacillin-tazobactam against strains of Escherichia coli and proteus mirabilis harbouring known beta-lactamases. 164 71

Piperacillin (PIP) alone and combined with 4 mg/l, 8 mg/l of tazobactam (TAZ) were tested by MIC determination on Mueller-Hinton agar against 224 clinical strains of P. aeruginosa: "wild type" (BLA-), 32 producing a constitutive cephalosporinase (CEP), 41 producing the PSE-1 type beta-lactamase, 7 PSE-2, 8 PSE-3, 9 PSE-4, 13 TEM-1, 24 TEM-2, 13 OXA-1, 22 OXA-2, 5 OXA-3. The combination with 8 mg/l was more effective than that one with 4 mg/l. Combinations of PIP-TAZ 8 mg/l reduced the MICs of PIP for the resistant strains (MICs greater than 64 mg/l) to the susceptible ot the moderately susceptible range (MICs less than or equal to 64 mg/l) for 31% of the CEP producing strains, 63% of the PSE-1, 15% of the PSE-2, none of the PSE-3, 34% of the PSE-4, 39% of the TEM-1, 30% of the TEM-2, 23% of the OXA-1, 14% of the OXA-2, 27% of the OXA-3, TAZ is the first beta-lactamase inhibitor effective against the constitutive cephalosporinase of P. aeruginosa; it is also very effective against the most frequently found PSE-1 beta-lactamase in P. aeruginosa.
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PMID:[In vitro activity of tazobactam and piperacillin combination against 224 strains of Pseudomonas aeruginosa according to the production of beta-lactamase]. 165 26

Cefcanel is a new orally absorbed cephalosporin. Its activity was compared with that of cefuroxime, cefaclor, cephalexin, and cefixime against gram-positive and negative aerobic and anaerobic bacteria. Cefcanel had excellent activity against methicillin-susceptible Staphylococcus aureus and Staphylococcus epidermidis, MIC90 1 micrograms/ml, superior to the other oral cephalosporins. However, methicillin-resistant staphylococci were resistant, MIC greater than or equal to 16 micrograms/ml. Streptococcus pyogenes and Streptococcus pneumoniae were inhibited by 0.015-1 micrograms/ml, concentrations comparable to other cephalosporins. Clostridium spp. were inhibited by 0.25 micrograms/ml, 8- to 128-fold lower concentrations than were found for other agents, but the MICs were greater than 64 micrograms/ml for Bacteroides spp. The MIC90 for Moraxella catarrhalis was 1 micrograms/ml, similar to cefuroxime but 16-fold greater than the MICs of cefixime. Escherichia coli and Klebsiella pneumonia which were high beta-lactamase producers were resistant, MICs greater than 64 micrograms/ml, and 50% of Enterobacter cloacae and Citrobacter freundii were resistant. Cefcanel was hydrolyzed by TEM-1, TEM-3 and Moraxella Bro-1 beta-lactamases. Escherichia coli containing TEM-1, 2, 3, 5, 7, and 9 had cefcanel MICs of greater than or equal to 16 micrograms/ml. Although cefcanel inhibited gram-positive species as well as or at lower concentrations than other cephalosporins, it lacked activity against gram-negative species that produced common plasmid beta-lactamase although it inhibited Haemophilus influenzae carrying TEM-1.
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PMID:In vitro activity of cefcanel versus other oral cephalosporins. 174 25


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