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Biomedical subjects

K P Fu

Publications and source records attributed to K P Fu.

At least 37 records · Page 2Linked to original sources

Experimental efficacy of apalcillin and cefpiramide compared with that of six other antipseudomonal agents in Pseudomonas aeruginosa burn infections.

The therapeutic efficacy of cefpiramide and apalcillin was evaluated and compared with that of six other antipseudomonal beta-lactam antibiotics in an experimental mouse burn infection due to Pseudomonas aeruginosa. Both cefpiramide and apalcillin were as potent as cefsulodin and more potent than carbenicillin, cefotaxime, cefoperazone, piperacillin and gentamicin in protecting the infected mice from fatal bacteraemia and in eradicating Ps. aeruginosa from the infected site.

Ampicillin↗

Efficacy of rifampicin in experimental Bacteroides fragilis and Pseudomonas aeruginosa mixed infections.

Experimental intraabdominal abscesses were produced in mice by intraperitoneal injection of Bacteroides fragilis and Pseudomonas aeruginosa. The therapeutic efficacy of rifampicin and cefsulodin alone, and in combination was investigated in this in-vivo experimental mixed intraabdominal abscess model. Treatment with rifampicin at 10, and 25 mg/kg or cefsulodin at 50, and 100 mg/kg singly or in combinations prevented mortality as compared to 68% mortality rate occurring in the untreated mice. Rifampicin, at 25 mg/kg dose, was very effective in preventing abscess formation and produced bacterial eradication. It prevented abscess formation in 80% of the mice and eradicated both Bacteroides and Pseudomonas in 100% and 75% of the abscesses of the mice. Cefsulodin failed to reduce the incidence of abscess formation, and to eradicate Bact. fragilis from the abscesses, although it significantly decreased Ps. aeruginosa in the abscesses. The combination of rifampicin at 10 mg/kg and cefsulodin at 100 mg/kg was more effective than either of the antibiotics alone and was as effective as rifampicin alone at 25 mg/kg levels. This combination was bactericidal against both organisms in the infected mice.

Abscess↗

Inhibitory activity of cefpiramide on beta-lactamase.

The beta-lactamase stability and inhibitory activity of cefpiramide were investigated. Cefpiramide was found to be stable to hydrolysis and inhibited beta-lactamase produced by Citrobacter freundii, Enterobacter cloacae, Morganella morganii, and Escherichia coli. Kinetic studies showed that cefpiramide is a competitive inhibitor of cephaloridine hydrolysis by E. cloacae beta-lactamase.

Cefotaxime↗

Experimental efficacy and pharmacokinetic properties of cefpiramide, a new cephalosporin.

The in vivo therapeutic efficacy of cefpiramide was investigated and compared with that of cefoperazone. Cefpiramide was more potent than cefoperazone against infections produced by both beta-lactamase-producing and non-beta-lactamase-producing S. aureus. The protective activity of cefpiramide against experimental infections with selected members of Enterobacteriaceae was lower than that of cefoperazone. Against carbenicillin-resistant P. aeruginosa infections, cefpiramide was as active as gentamicin and aztreonam and three times more potent than cefoperazone, cefotaxime and piperacillin. The pharmacokinetic properties of cefpiramide in mice and rats were superior to those of cefotaxime and cefoperazone. The peak serum concentrations of cefpiramide, administered subcutaneously at a dose of 50 mg/kg, were 76 micrograms/ml in mice and 174 micrograms/ml in rats and the corresponding serum half-lives of cefpiramide were 87 min and 49 min in mice and rats respectively.

Animals↗

Pharmacokinetics of ceftriaxone after intravenous infusion and intramuscular injection.

The pharmacokinetics of ceftriaxone were evaluated in eight adults after doses of 1 g administered by intravenous infusion and 1 and 0.5 g administered by intramuscular injection. Mean peak plasma concentrations were 168 micrograms/ml for 1 g given intravenously, 81 micrograms/ml for 1 g given intramuscularly, and 46 micrograms/ml for 0.5 g intramuscularly. Plasma concentrations were similar by both high pressure liquid chromatographic and microbiologic methods. The plasma half-lives were 7.6 and 8.3 hours, respectively, for the intravenous infusion and intramuscular injection. Plasma concentrations were equal for the 1 g intravenous and intramuscular routes by 2.5 hours. Plasma concentrations exceeded the minimal inhibitory concentrations (MICs) of most aerobic gram-positive and gram-negative organisms with the exception of Pseudomonas aeruginosa and Acinetobacter species for 24 hours. Urinary concentrations exceeded 100 micrograms/ml for 24 hours for the 1-g doses and for 12 hours for the 0.5-g dose. Urinary recovery of ceftriaxone within 24 hours was 40 percent for intravenous infusion and 33 and 34 percent for the intramuscular injection. A single 1-g dose daily will exceed the MICs of most staphylococcal and streptococcal species and Enterobacteriaceae for 12 to 24 hours.

Adult↗

Synergistic activity of cefsulodin combined with cefoxitin and sulbactam against Bacteroides species.

The in-vitro activity of cefsulodin combined with sulbactam, cefoxitin or cefotaxime was investigated against 32 strains of beta-lactamase-producing Bacteroides species. Synergy of cefsulodin-sulbactam or cefsulodin-cefoxitin could be demonstrated against 30 of 32 and 32 of 32 strains tested at the concentrations readily achievable in serum. In the presence of 1 mg/l of sulbactam or cefoxitin, more than 90% of the Bacteroides isolated were inhibited by 32 mg/l of cefsulodin. The inhibitory activity of cefsulodin-sulbactam or cefsulodin-cefoxitin combinations was bactericidal against Bact. fragilis and Bact. vulgatus. In contrast, no synergistic inhibitory or bactericidal activities can be observed by the cefsoludin-cefotaxime combination. Both sulbactam and cefoxitin were potent inhibitors of beta-lactamases produced by Bact. fragilis and Bact. melaninogenicus suggesting that this inhibitory activity might be one of the factors contributing to the synergistic combinations.

Bacteroides↗

Therapeutic efficacy and pharmacokinetic properties of rifampicin in a Bacteroides fragilis intra-abdominal abscess.

The efficacy of rifampicin in treating a Bacteroides fragilis infection was investigated and compared to clindamycin and metronidazole in an experimental model of intra-abdominal abscess in mice. Rifampicin, when given subcutaneously, showed activity superior to that of clindamycin in reducing the incidence of abscess formation as well as the number of Bacteroides organisms recovered from the abscess, and rifampicin was comparable in efficacy to metronidazole when given orally at the same dose level. The comparative pharmacokinetic properties of rifampicin and clindamycin demonstrated that the peak serum and abscess levels reached with rifampicin were significantly higher than those of clindamycin. The half-life of rifampicin in serum and in the abscess was longer than that of clindamycin.

Abscess↗

Antimicrobial susceptibility, growth kinetic and pathogenicity of thymidine-requiring Streptococcus species.

18 strains of thymidine-requiring streptococcal mutants (thy-) were isolated from urines of patients with urinary tract infection treated with trimethoprim-sulfameth-oxazole (TMP-SMZ) or trimethoprim-sulfadiazine (TMP-SDZ). All thy- mutants were catalase- and beta-lactamase-negative, grew in the presence of bile and esculin, and required from 0.3 to greater than 1280 micrograms/ml of thymidine for normal growth. The antibiotic susceptibility of wild-type and thy- mutants to 21 antimicrobial agents tested were comparable except to trimethoprim (TMP), TMP-SMZ and TMP-SDZ. Ampicillin, penicillin G, erythromycin and rifampin were among the most active compounds tested. Growth kinetic studies with a Streptococcus faecalis thy- mutant in a synthetic basal medium without thymidine resulted in a decrease of 2-3 logarithmic units in viable cells after 24 h of incubation. The addition of thymidine to this thymidine-deprived culture prevented the thymineless death of the cells. In vivo, this thy- mutant was less virulent than the wild-type strain in producing kidney infection in mice.

Animals↗

Pharmacokinetics of moxalactam and cefazolin compared in normal volunteers.

The pharmacokinetics of moxalactam, a new beta-lactam antibiotic with an unusually broad spectrum of activity, were studied in normal volunteers and compared with the pharmacokinetics of cefazolin. After a 1,000-mg intramuscular injection of moxalactam, a mean peak serum level of 49 +/- 10 micrograms/ml was achieved at 30 to 60 min which was equivalent to the level achieved with 0.5 g of cefazolin. Serum levels of 4.57 +/- 0.63 micrograms/ml, above the inhibitory levels for most organisms, were present at 8 h. The half-life of moxalactam was 2.3 h. After a 30-min intravenous infusion of 1 g, the serum level of moxalactam was 60 +/- 18.8 micrograms/ml. This compares with a serum level of 70 micrograms/ml obtained with an infusion of 0.5 g of cefazolin. At 6 h, 3.59 +/- 0.68 microgram/ml of moxalactam was present. The half-life of moxalactam was 2.3 h, similar to that of cefazolin. By 1 h after administration, serum levels of moxalactam were higher after intramuscular administration than after intravenous delivery. Urinary recovery of the drug was 76% after intramuscular injection and 74% after intravenous infusion, with the majority of the drug having been excreted in the first 4 h after administration. Urinary recovery of cefazolin was 85%. The pharmacokinetics of moxalactam are similar to those of cefazolin.

Adult↗

Antibacterial activity of ceftriaxone (Ro 13-9904), a beta-lactamase-stable cephalosporin.

The in vitro activity of ceftriaxone (Ro 13-9904), a parenteral cephalosporin, was compared with that of other beta-lactam antibiotics. the compound was less active against Staphylococcus aureus and Staphylococcus epidermidis than was cephalothin or cefamandole, but it was comparable to cefoxitin, cefotaxime, and moxalactam in inhibiting most isolates of S. aureus at 3.1 microgram/ml. Ro 13-9904 inhibited Streptococcus pyogenes and Streptococcus pneumoniae at concentrations below 0.25 microgram/ml, but Streptococcus faecalis required concentrations above 25 microgram/ml. Neisseria gonorrhoeae and Haemophilus influenzae were inhibited at concentrations similar to those of cefotaxime, less than 0.1 microgram/ml. Ro 13-9904 was as active as cefotaxime and moxalactam against most Enterobacteriaceae and was the most active agent tested against Proteus, inhibiting all strains tested at 0.006 microgram/ml. Ro 13-9904 was slightly less active than moxalactam or cefoxitin against Bacteroides fragilis, requiring more than 100 microgram/ml to inhibit 90% of isolates, and it was less active than cefoperazone against Pseudomonas aeruginosa. Presence of serum, alteration of pH, and use of various media did not change the inhibitory levels. Bactericidal concentrations were similar to inhibitory levels. Ro 13-9904 was stable to most plasmid-mediated beta-lactamases, but was hydrolyzed by some Enterobacter, Proteus, and Bacteroides beta-lactamases of chromosomal origin.

Bacteria↗

Cefotaxime kinetics after intravenous and intramuscular injection of single and multiple doses.

The kinetics of cefotaxime, a cephalosporin with an unusually broad antibacterial spectrum, were examined in humans after intravenous bolus injection, intravenous infusion every 6 hr for 14 days, and intramuscular injection every 8 hr for 10 days. Mean peak serum level after bolus injection of 500 mg was 37.9 microgram/ml; after 1 gm, 102.4 microgram/ml; and after 2 gm, 214.1 microgram/ml. The half-life (t1/2) was 1 hr for the 3 doses. Total serum clearance was the same for all doses. Overall excretion was 50% to 60%; part of the drug was excreted as the desacetyl derivative. After multiple intravenous infusion the elimination rate constants and t1/2 were the same on days 1 and 15. Assayable levels were present on all days 5 min before injection of a dose. Multiple intramuscular injections of 500 mg produced serum levels of 9.2 to 11.9 microgram/ml. The t1/2 was 0.93 hr. Mean serum levels at 8 hr ranged from 0.08 to 0.55 microgram/ml. Serum levels produced by intravenous infusion or intramuscular injection were inhibitory for most (90%) aerobic gram-positive and gram-negative organisms susceptible to cefotaxime.

Adult↗

Antibacterial activity of ceftizoxime, a beta-lactamase-stable cephalosporin.

The in vitro activity of ceftizoxime was compared with that of other beta-lactam antibiotics against 538 isolates. Ceftizoxime was the most active agent tested against Escherichia coli and Klebsiella, inhibiting 80% at 0.025 microgram/ml. It was more active than cefotaxime against Enterobacter cloacae and E. aerogenes. Ceftizoxime was more active than cefoxitin, cefotaxime, cefoperazone, and carbenicillin against Proteus mirabilis and indole-positive Proteus. It inhibited 97% of multiresistant Serratia isolates at 12.5 microgram/ml, whereas cefotaxime inhibited only 19%. Ceftizoxime was less active than cefotaxime and cefoperazone against Pseudomonas aeruginosa, but was more active than carbenicillin. It was more active than cefotaxime and cefoxitin against Bacteroides. It was not appreciably destroyed by beta-lactamases of Staphylococcus aureus, Enterobacteriaceae, or Pseudomonas.

Acinetobacter↗

In vitro activity of chloramphenicol and thiamphenicol analogs.

The in vitro activity of three fluorine analogs of chloramphenicol in which the hydroxyl group at position 3 had been replaced with a fluorine was compared with that of chloramphenicol and thiamphenicol. Compound SCH 24893 was the most active agent against staphylococci and Bacteroides strains, and compound SCH 25298 was the most active against Haemophilus, Neisseria, enterococcus, and Klebsiella strains. Serratia marcescens and Pseudomonas aeruginosa strains resistant to chloramphenicol were resistant to the compounds. The agents inhibited all of the Shigella, Salmonella, Staphylococcus aureus, and enterococcus strains resistant to chloramphenicol. They inhibited most (82%) of Escherichia coli and half of the Klebsiella pneumoniae strains which were resistant to chloramphenicol. Isolates in which resistance to chloramphenicol was shown to be plasmic mediated and due to chloramphenicol transacetylase were inhibited by all three agents.

Bacteria↗

Synergistic activity of piperacillin in combination with beta-lactamase inhibitors.

Clavulanic acid and a penicillanic acid sulfone, when combined individually with piperacillin, synergistically inhibited various Enterobacteriaceae, Staphylococcus aureus, and Bacteroides fragilis. Clavulanic acid and piperacillin synergistically inhibited 91 of 170 (55%) isolates tested. Synergy was most often found against piperacillin-resistant bacteria: 65 of 69 isolates (94%). Although the penicillanic acid sulfone acted synergistically with piperacillin, inhibiting 62 of 170 strains (33%), the concentration of clavulanic acid required for synergy generally was less than that of penicillanic acid sulfone. Combination of piperacillin and cefotaxime, an inhibitor of type 1 beta-lactamases, rarely was synergistic and was antagonistic for several species. The combination of piperacillin with potent beta-lactamase inhibitors made piperacillin active against those isolates of Escherichia coli and Klebsiella and Bacteroides species, as well as selected other species, that are resistant to piperacillin by virtue of their production of beta-lactamases.

Anti-Bacterial Agents↗