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P Actor

Publications and source records attributed to P Actor.

At least 19 recordsLinked to original sources
PubMed1995

Susceptibilities of nontuberculosis mycobacterial species to amoxicillin-clavulanic acid alone and in combination with antimycobacterial agents.

Neither amoxicillin nor clavulanic acid used alone was active at the highest level tested, i.e., 256.0 micrograms/ml, in vitro against 24 isolates of Mycobacterium fortuitum, Mycobacterium kansasii, and Mycobacterium marinum. However, the MIC of an amoxicillin-clavulanic acid combination of 2:1 was < or = 8.0/4.0 micrograms/ml for 50 percent of the isolates tested, with all isolates being inhibited in the range of 4.0/2.0 to 32.0/16.0 micrograms/ml, respectively. Titration of amoxicillin-clavulanic acid with a fixed 2-micrograms/ml concentration of ethambutol resulted in synergistic activity against 3 of 9 isolates of M. fortuitum, 10 of 10 isolates of M. kansasii, and 5 of 5 isolates of M. marinum. This observation was confirmed in a checkerboard analysis in which fractional inhibitory concentrations were < or = 0.5 for 20 of the 24 isolates. Synergistic activity was observed against the other four isolates in one of two trials. On the other hand, titration of amoxicillin-clavulanic acid in the presence of either one or two fixed concentrations of isoniazid, rifampin, cycloserine, tetracycline, or amikacin failed to result in synergism.

Amoxicillin↗
PubMed1985

Indications that the erythrocyte receptor involved in enterotoxigenic Escherichia coli attachment is a sialoglycoconjugate.

A reverse hemagglutination assay was used to study adherence to human erythrocytes by Escherichia coli H10407, which possesses colonization factor antigen I. Pretreatment of erythrocytes with trypsin, chymotrypsin, papain, protease, and neuraminidase completely abolished attachment reactivity. In addition, the hemagglutination reaction was prevented by the presence of urea and guanidine. In contrast, the lipases, nucleotide hydrolases, exoglycosidases, and reagents affecting disulfide or sulfhydryl moieties did not alter receptor reactivity. Glycoconjugates containing sialic acid inhibited the hemagglutination reaction. Furthermore, a sialoglycoprotein isolated from the erythrocyte membrane inhibited the hemagglutination reaction. Collectively, these data indicate that the erythrocyte receptor responsible for attachment by E. coli possessing colonization factor antigen I is a sialoglycoconjugate.

Adhesiveness↗
PubMed1985

Enoxacin: a potent inducer of filamentous Escherichia coli cells (a note).

Enoxacin (CI-919; AT-2266), a new naphthyridine derivative was found to induce morphologic changes at very low concentrations in Escherichia coli but not in Staphylococcus aureus and Pseudomonas aeruginosa cells. The development of the long filamentous forms observed with nalidixic acid is most probably a consequence of inhibition of DNA synthesis. The phenomenon may, however, not be the sole mechanism of the broad-spectrum antimicrobial activity of enoxacin.

Anti-Bacterial Agents↗
PubMed1984

Anti-Candida activity of polyoxin: example of peptide transport in yeasts.

The polyoxins, nucleoside peptide antibiotics, are effective inhibitors of chitin synthesis in some fungi and yeasts. Although isolated chitin synthetases appear to be equally sensitive to inhibition by polyoxins, intact yeast cells are relatively insensitive. It has been suggested that polyoxins enter cells by a peptide carrier transport mechanism. In this paper, we report results which demonstrate that changes in the growth conditions significantly affect the degree of sensitivity of Canidida albicans to the polyoxins. For example, a minimal inhibitory concentration of 0.1 micrograms/ml was obtained in a defined medium compared with a minimal inhibitory concentration of 1,000 micrograms/ml with conventional media. Various noninhibitory di- and tripeptides, when added to the media, were found to antagonize the anti-Candida activity of polyoxins. In addition, polyoxin-resistant mutants of C. albicans were shown to exhibit cross-resistance with other dipeptide antibiotics. The data reported herein support peptide transport of polyoxins in C. albicans.

Antifungal Agents↗
PubMed1984

Antimicrobial activity of SK&F 88070, an expanded-spectrum cephalosporin with high and prolonged levels in blood.

SK&F 88070 (7-[[(2-amino-4-thiazolyl)(methoxyimino)acetyl]amino]-3- [[[1-(2-sulfaminoethyl)-1H-tetrazol-5-yl]thio] methyl]-3-cephem-4-carboxylic acid) is a new parenteral cephalosporin with an expanded-spectrum profile of antibacterial activity, including activity against Pseudomonas aeruginosa, and with high and prolonged levels in sera of experimental animals. The activity of SK&F 88070 was compared with those of cefotaxime and other cephalosporins against more than 500 clinical isolates in vitro by microtiter twofold dilution tests in Mueller-Hinton broth. SK&F 88070 was extremely potent against all of the members of the family Enterobacteriaceae that were tested, including beta-lactamase-producing strains. Its activity against P. aeruginosa was comparable to those of cefotaxime, ceftizoxime, and moxalactam. SK&F 88070 was less potent than cefotaxime or ceftizoxime against Staphylococcus species but was comparable to moxalactam. It had in vivo activity against the same Bacteroides strains as did cefotaxime, although it was less potent. Both SK&F 88070 and cefotaxime had less activity when tested with high inoculum levels of most of the rarer gram-negative bacteria. There was a greater decrease in the activity of SK&F 88070 than of cefotaxime in the presence of human serum, reflecting the higher degree of binding of SK&F 88070 to serum proteins. SK&F 88070 had peak levels and half-lives in serum much greater than those of cefotaxime in experimental animals after parenteral administration. In mouse protection studies, SK&F 88070 was more effective than cefotaxime against gram-negative bacteria but less effective than cefotaxime against Staphylococcus aureus.

Animals↗
PubMed1984

Activity of ceftizoxime and comparative compounds against Bacteroides fragilis in a mouse model of anaerobic infection.

A new mouse model of anaerobic infection with Bacteroides fragilis alone or in a mixed infection with Escherichia coli is described. It is established by implantation under the skin of a filter paper disk saturated with the appropriate bacterial suspension. The penetration of antibiotics into the implantation site can be detected by assaying the disk. The local infection can be both standardized and evaluated by determining the bacterial count on the disk. The antimicrobial efficacy of ceftizoxime was compared with other commercially available antibiotics administered in a single dose, 40 mg/kg subcutaneously, one hour after implantation of the disk. Using such a regimen ceftizoxime was found to be superior to a clindamycin-gentamicin combination and equal to or superior to cefoxitin in these models.

Animals↗
PubMed1984

Affinity of cefonicid, a long-acting cephalosporin, for the penicillin-binding proteins of Escherichia coli K-12.

The binding of cefonicid (SK&F 75073), a new parenteral cephalosporin, to the penicillin-binding proteins (PBPs) of Escherichia coli K-12 (strain KN-126) was determined by competitive binding studies versus benzyl[14C]penicillin. Cefonicid showed its greatest affinity for PBPs 1a greater than 3 greater than 1b, bound with low affinity to PBPs 4 greater than 2, and did not bind to PBPs 5 and 6. Provisional affinity constants (cefonicid concentration that gave 50% inhibition of [14C]penicillin binding) were determined: PBP 1a, less than 0.25 microgram/ml; PBP 3, 0.7 microgram/ml; PBP 1b, 10 micrograms/ml; PBP 4, 26 micrograms/ml; PBP 2, 90 micrograms/ml; PBPs 5 and 6 greater than 256 micrograms/ml. Direct binding studies with [14C]-cefonicid confirmed this pattern of binding. Subinhibitory concentrations of cefonicid (MIC, broth 0.2 microgram/ml, agar 0.4 microgram/ml) induced filamentation of E. coli KN-126. This implies that PBP 3 is the primary inhibitory site despite the higher affinity of PBP 1a for this cephalosporin.

Bacterial Proteins↗
PubMed1984

Five cephalosporins: pharmacokinetics and their relation to antibacterial potency.

In a group of adult volunteers, pharmacokinetic profiles of five cephalosporins were correlated with their minimal inhibitory concentrations (MICs90) against Staphylococcus aureus, Streptococcus pyogenes, Streptococcus pneumoniae, Escherichia coli, Klebsiella pneumoniae, Proteus mirabilis, and Enterobacter aerogenes. Subjects received the following intravenous regimens in a randomized, crossover fashion: (1) 0.5 gm, 1 gm, or 2 gm of cefazolin; (2) 2 gm of cephalothin; (3) 1 gm of cephapirin; (4) 1 gm of cefoxitin; or (5) 0.5 gm of cefamandole. The 500-mg dose of cefazolin produced serum concentrations that exceeded those of any of the other cephalosporins at 0.5, 1, 2, 4, and 6 hours after administration. The area under the curve for this dose of cefazolin was at least twice that of any of the other antibiotics. Two hours after a 500-mg dose of cefazolin, serum levels exceeded the MIC90 for all seven groups of pathogens; at six hours, the 500-mg dose of cefazolin continued to achieve serum levels above the MIC90 against the majority of bacterial groups. In contrast, at two hours after administration none of the other cephalosporins maintained serum levels above the MIC90 for all pathogens; at six hours, the levels of cephapirin were adequate to inhibit the two streptococci, but serum levels of all other cephalosporins were inadequate to inhibit any of the pathogens. These data indicate that a 500-mg dose of cefazolin maintains serum levels above the MICs90 longer than any of the other cephalosporins tested and support the use of a 500-mg dose of cefazolin every eight hours for surgical prophylaxis and treatment of most community-acquired infections. Such a comparatively low dosage offers substantial savings to both patient and hospital.

Adult↗
PubMed1982

Precipitate formation of some sulfonated tetrazolthiomethyl cephalosporins with basic chemicals.

Cephalosporins containing a thiomethyltetrazole-sulfomethyl or sulfoaminoethyl substituent at the three-position react in aqueous solution with protamine or quinine to form a precipitate. This phenomenon may provide some insight into their pharmacokinetics and modes of action especially as it relates to the high and prolonged serum levels and high degree of serum protein-binding.

Blood Proteins↗
PubMed1982

Ceftizoxime kinetics and renal handling.

The kinetics and renal handling of ceftizoxime were examined after intravenous and intramuscular injection and the effect of probenecid on its excretion was investigated. Peak serum level after 1000 mg IV was 60.5 microgram/ml and half-life (t 1/2) was 1.4 hr. Peak serum level (40.9 microgram/ml) was reached 1 hr after 1000 mg IM. When probenecid was added to the 1000-mg IM dose the peak level was 44.3 microgram/ml at 1 hr and serum levels at 2, 4, 6, and 8 hr were all higher than after ceftizoxime alone (P less than 0.01). The 1.85-hr t 1/2 of ceftizoxime alone was extended to 2.29 hr when probenecid was added. Ceftizoxime was shown to be actively secreted by the renal tubule; this secretion was decreased by probenecid.

Anti-Bacterial Agents↗
PubMed1982

Use of a hemadsorption technique to evaluate the stability of the hemagglutination reaction of Escherichia coli cultures possessing human colonization factor antigens.

Two strains of Escherichia coli, producing different colonization factor antigens (CFA), were monitored for the population density of CFA-producing bacteria after repeated subculture. The production of CFA was estimated by flooding agar plates containing isolated colonies with suspensions of human or bovine erythrocytes. The erythrocytes were suspended in a low-ionic-strength buffer and were fixed to CFA-positive colonies with a 1.0% tannic acid solution. Strain H-10407, possessing CFA/I fimbriae, showed a rapid loss of the hemagglutinin when subcultured, whereas strain CL-9699, producing CFA/II, was very stable. By using the hemadsorption assay, we could rapidly and easily distinguish CFA- positive colonies from the CFA-negative variants. A survey of additional E. coli strains demonstrated the utility and specificity of the hemadsorption technique used.

Animals↗
PubMed1982

Isopycnic separation of Escherichia coli cultures possessing colonization factor antigen I.

A culture of Escherichia coli possessing colonization factor antigen I was subjected to isopycnic separation on Percoll gradients. The results demonstrated successful division of the culture into two populations: (i) bacteria which cause mannose-resistant hemagglutination and (ii) bacteria which lack the ability to hemagglutinate in the presence of mannose.

Antigens, Bacterial↗
PubMed1982

Aculeacin A resistant mutants of Candida albicans.

Mutants of Candida albicans resistant to aculeacin A, a yeast cell-wall inhibitor, were isolated after mutagenesis with ultraviolet light. The parental strain was sensitive to 0.1 approximately 0.5 microgram/ml of the antibiotic. In contrast, the minimum inhibitory concentration for the mutants ranged from 50 to 200 microgram/ml. Except for papulocandin, another cell-wall inhibitor, the antibiotic susceptibility of the mutants was similar to the parental strain. The parent strain and the aculeacin resistant mutants exhibited similar morphological changes at subinhibitory levels of aculeacin and had comparable growth rates on complex media. The lipid and sterol content of the parent and the mutants were significantly different. For example, the total lipid content was two-fold higher in the mutant strains. Drug resistance in the mutants was specific for aculeacin and papulocandin and appeared to be associated with alteration in the lipid composition of membranes.

Antifungal Agents↗
PubMed1981

Kinetics and renal handling of cefonicid.

Cefonicid kinetics were determined after intravenous and intramuscular injection and the renal handling of the drug was examined, including the effect of probenecid on its excretion. Peak serum levels after 1000 and 500 mg intravenously was 221 and 91 micrograms/ml. The half-life (t1/2) was the same for both regimens (3.5 hr). Intramuscular injection of the 1000- and 500-mg doses resulted in peak serum levels of 112 and 40 micrograms/ml. When probenecid was given with the 500-mg dose, the peak serum level was 61 micrograms/ml and the time to peak level rose from 1.3 to 2.5 hr. The t1/2 after 1000 and 500 mg alone was much the same at 4.8 and 4.9 hr. The addition of probenecid to the 500-mg dose extended the t1/2 and 7.5 hr. Renal clearance, excretion, and secretion rates for cefonicid were reduced by the addition of probenecid. Cefonicid's long t1/2 and high blood levels may provide clinical efficacy with a single daily dose.

Adult↗