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Biomedical subjects

M E Valiant

Publications and source records attributed to M E Valiant.

13 recordsLinked to original sources
PubMed1989

L-658,310, a new injectable cephalosporin. I. In vitro antibacterial properties.

The in vitro antibacterial spectrum of L-658,310, a new semisynthetic cephalosporin, was compared with ceftazidime, aztreonam and piperacillin against a wide variety of randomly selected human clinical isolates. The compound was found to be a broad spectrum bactericidal agent that was more potent than any of the comparison drugs against glucose nonfermenting bacteria. It has especially potent activity against Pseudomonas aeruginosa including multiply-resistant strains. The superior activity of L-658,310 against this group of organisms is attributed to the presence of the dihydroxy substituents on the 2-methylisoindoline moiety of the compound. L-658,310 is not cross-resistant with either imipenem, ceftazidime or piperacillin (representatives of three different classes of beta-lactam compounds) against P. aeruginosa. The lack of cross-resistance with ceftazidime extends to other glucose nonfermenters and several strains of Enterobacteriaceae as well. The compound is active against bacteria known to possess either R-plasmid- or chromosomally-mediated beta-lactamases.

Aerobiosis↗
PubMed1989

L-658,310, a new injectable cephalosporin. II. In vitro and in vivo interactions between L-658,310 and various aminoglycosides or ciprofloxacin versus clinical isolates of Pseudomonas aeruginosa.

Combinations of L-658,310 and an aminoglycoside or ciprofloxacin were tested against clinical isolates of Pseudomonas aeruginosa using a checkerboard broth dilution technique. Using the mean fractional bactericidal concentration of less than or equal to 0.5 as the criterion for synergy, the combinations L-658,310/tobramycin and L-658,310/ciprofloxacin against strains of P. aeruginosa resistant to the companion drug were synergistic. The data plotted as isobolograms showed synergy for all combinations tested. Synergy was clearly demonstrated in time-kill experiments. A greater than 3-log decrease in viable cell count for P. aeruginosa was seen after exposure for 24 hours to subinhibitory concentrations of the combined agents. In in vivo mouse models, the efficacy of L-658,310 against experimental P. aeruginosa bacteremias was enhanced by the addition of a low dose of an aminoglycoside to the treatment regimen, thus confirming the synergy demonstrated in time-kill experiments.

Amikacin↗
PubMed1988

Antibacterial activities of fluorovinyl- and chlorovinylglycine and several derived dipeptides.

The in vitro antibacterial activities of several halovinylglycine compounds and their L-norvalyl peptide derivatives are presented. The most potent of them, L-norvalyl-L-chlorovinylglycine, displayed good activity against gram-positive organisms, including methicillin-resistant Staphylococcus species. Chlorovinylglycine is an efficient inhibitor of alanine racemase, but the antibacterial activity of L-norvalyl-L-chlorovinylglycine may involve other physiological targets as well.

Anti-Bacterial Agents↗
PubMed1988

L-656,575 (OCP-9-176): a novel oxacephem. In vitro activity against aerobic and anaerobic clinical bacterial isolates.

L-656,575 (OCP-9-176) is a novel oxacephem superior to ceftazidime in in vitro activity against clinical isolates of Enterobacter species, methicillin-susceptible Staphylococcus aureus and Staphylococcus epidermidis, and multiply-resistant Pseudomonas aeruginosa. Our results suggest that L-656,575 has a high affinity for penicillin binding proteins of Pseudomonas and may bind preferentially to PBP-3 in this organism. L-656,575 is active against beta-lactamase derepressed Enterobacteriaceae and ceftazidime-resistant P. aeruginosa.

Animals↗
PubMed1979

Antibacterial activity of heneicomycin.

Heneicomycin is structurally similar to efrotomycin, mocimycin (kirromycin) and X-5108 (goldinomycin). Comparisons were limited because of the small supplies available. All antibiotics show the same in vitro antibacterial spectrum although some test cultures were less sensitive to efrotomycin. Heneicomycin compared favorably with efrotomycin when given subcutaneously or per os against infections with Moraxella bovis and Streptococcus pyogenes. The raid elimination of heneicomycin observed following oral administration may account for its poor activity against a Bordetella bronchiseptica infection where efrotomycin is effective. It appears more like X-5108 than efrotomycin biologically. The disaccharide on efrotomycin may account for the difference observed.

Animals↗
PubMed1976

In vitro and in vivo activity of 3-(1-methyl 1-5-nitro-2-imidazolylmethylideneamino)-2-oxazolidinone against Pasteurella.

Furazolidone was more active than 3-(1-methyl)-5-nitro-2-imidazolyl-methylideneamino)-2-oxazolidinone (MABN) against a series of 34 isolates of Pasteurella and 11 of Yersinia (formerly designated Pasteurella). However, the nitroimidazole was superior to furazolidone by both subcutaneous and oral routes against a series of mouse infections incited by strains of Pasteurella. It also was superior to furazolidone and sulfaquinoxaline when administered in the diet against two Pasteurella strains in a fowl cholera model infection in chickens. The good in vitro activity of MABN plus its low toxicity suggest its further study as an agent for fowl cholera and the shipping fever complex of cattle.

Animals↗
PubMed1976

Antibacterial activity of efrotomycin.

Efrotomycin is a narrow spectrum antibiotic. Among the genera tested for susceptibility in vitro it is most active against isolates of Moraxella, Pasteurella, Yersinia, Haemophilus, Streptococcus and Corynebacterium. The drug is as active by oral administration as by the subcutaneous route. Blood levels rise rapidly to high concentrations, after oral dosing, and are prolonged. Two peaks occur which may indicate biliary excretion and reabsorption. Urinary excretion is minimal. The high blood concentrations explain, in part, the in vivo activity against pathogens such as Bordetella bronchiseptica which are relatively insensitive in vitro. Oral activity of efrotomycin is an advantage over the related antibiotics. X-5108 and mocimycin.

Animals↗