Biomedical subjects

K P Fu

Publications and source records attributed to K P Fu.

66 records · Page 4Linked to original sources

PubMed1978

Synergy of azlocillin and mezlocillin combined with aminoglycoside antibiotics and cephalosporins.

Synergistic activity between both azlocillin and mezlocillin and aminoglycosides or cefazolin could be demonstrated by checkerboard dilution, isobologram, and killing curve techniques. Azlocillin and mezlocillin combined with gentamicin, netilmicin, or amikacin were synergistic against Escherichia coli, Klebsiella, Citrobacter, Enterobacter, Serratia, and indole-positive Proteus. Synergy was observed with isolates that were susceptible or resistant to azlocillin or mezlocillin. Synergy was seen most often when azlocillin or mezlocillin were combined with amikacin, gentamicin, or netilmicin against Pseudomonas aeruginosa. The combination of mezlocillin and an aminoglycoside produced synergy more often than did carbenicillin plus an aminoglycoside. No antagonism was seen when aminoglycoside antibiotics were combined with azlocillin or mezlocillin. Cefazolin was synergistic against Pseudomonas, Providencia, P. mirabilis, indole-positive Proteus, Citrobacter, Klebsiella, and Escherichia coli, when combined with azlocillin or mezlocillin. However, the combination of either agent with cefazolin was antagonistic when tested against selected indole-positive Proteus and Enterobacter isolates.

Aminoglycosides↗

PubMed1978

Azlocillin and mezlocillin: new ureido penicillins.

The activity of azlocillin and mezlocillin, new semisynthetic ureido penicillins, was investigated and compared with that of other known beta-lactam antibiotics. At a concentration of 25 mug/ml, azlocillin inhibited 74% of Enterobacter, 97% of Proteus mirabilis, 64% of Citrobacter, 91% of Pseudomonas aeruginosa, and 82% of Bacteroides strains tested. Mezlocillin inhibited 86% of Shigella, 96% of Enterobacter, 80% of indole-positive Proteus, 88% of Bacteroides, and 63% of Pseudomonas strains tested. Azlocillin was more active against Pseudomonas than was ticarcillin, carbenicillin, or mezlocillin. Mezlocillin was more active than carbenicillin and ampicillin against Escherichia coli, Klebsiella, Enterobacter, Citrobacter, Acinetobacter, Serratia, and Bacteroides. Azlocillin and mezlocillin were less active than cefazolin against beta-lactamase-producing E. coli and Klebsiella strains but more active than cefazolin against Enterobacter, indole-positive Proteus, Acinetobacter, Citrobacter, and Serratia strains. Both compounds showed activity equivalent to that of cefoxitin against Bacteroides isolates. Both agents were destroyed by many of the beta-lactamases from gram-negative organisms.

Bacteria↗

PubMed1978

In vitro activity and beta-lactamase stability of BL-S786 compared with those of other cephalosporins.

In vitro activity of BL-S786, a new parenterally semisynthetic cephalosporin, was investigated against 570 bacterial isolates. BL-S786 inhibited most Escherichia coli, Klebsiella pneumoniae, Proteus mirabilis, and Salmonella. It inhibited some Enterobacter and indole-positive Proteus, but it was less active against these later species than was cefamandole, cefuroxime, or cefoxitin. It was not active against Serratia marcescens, Pseudomonas aeruginosa, or Bacteroides fragilis. BL-S786 was the least active new cephalosporin tested against staphylococci and was less active than cephalothin against streptococcal species. The activity of BL-S786 was not altered by the type of assay medium nor by 50% serum. The size of the test inoculum altered the minimal inhibitory and bactericidal concentrations for inhibition of some organisms, particularly those with Richmond type I beta-lactamases. BL-S786 was not hydrolyzed by the R-factor-mediated, Richmond type III beta-lactamase, but it was hydrolyzed by type I beta-lactamases.

Amidohydrolases↗

PubMed1978

Activity of 5-episisomicin compared with that of other aminoglycosides.

5-Episisomicin, a semisynthetic aminoglycoside, has been shown to inhibit many members of the Enterobacteriaceae, Pseudomonas aeruginosa, and Staphylococcus aureus. At a concentration of 3.1 mug/ml, more than 90% of Escherichia coli, Klebsiella pneumoniae, Enterobacter, Citrobacter, indole-positive Proteus, and Providencia were inhibited. 5-Episisomicin had activity against S. aureus, E. coli, Klebsiella, Enterobacter, and Citrobacter similar to gentamicin and netilmicin. It had activity similar to amikacin and netilmicin against many gentamicin-resistant bacteria. The activity of 5-episisomicin was greatest at an alkaline pH and in medium of low magnesium content. Synergy of 5-episisomicin and carbenicillin was found to occur most often against Pseudomonas.

Aminoglycosides↗

PubMed1978

beta-lactamase stability of HR 756, a novel cephalosporin, compared to that of cefuroxime and cefoxitin.

The stability to beta-lactamase hydrolysis of HR 756, a new cephalosporin antibiotic, was compared to the beta-lactamase stability of cefoxitin and cefuroxime. HR 756, cefoxitin, and cefuroxime were not hydrolyzed by Richmond type I, III, IV, and V beta-lactamases. Antibacterial activity of HR 756 correlated well with resistance to beta-lactamase hydrolysis except against Pseudomonas aeruginosa. HR 756, cefoxitin, and cefuroxime inhibited type I beta-lactamases, but not type III, IV, or V enzymes. HR 756 was the most active inhibitor.

Cephalosporins↗

PubMed1978

Clavulanic acid, a novel inhibitor of beta-lactamases.

Clavulanic acid, Z-(2R,5R)-3-(beta-hydroxyethylidene)-7-oxo-4-oxa-1-azabicyclo-[3,2,0] heptane-2-carboxylic acid, has been shown to be an effective inhibitor of the beta-lactamases of the Richmond types II, III, IV, and V. Inhibition is a time-dependent reaction and is irreversible. Clavulanic acid had poor antibacterial activity against Staphylococcus aureus, Enterobacteriaceae, and Pseudomonas aeruginosa, with minimal inhibitory levels greater than 25 mug/ml. It did inhibit the majority of Neisseria gonorrhoeae at 0.1 mug/ml and Haemophilus influenzae at 6.3 mug/ml. Clavulanic acid acted synergistically with penicillins and cephalosporins to inhibit beta-lactamase-producing S. aureus and Enterobacteriaceae. Clavulanic acid combined with ampicillin inhibited beta-lactamase-producing N. gonorrhoeae, H. influenzae, Escherichia coli, Salmonella typhi, and Shigella sonnei.

Ampicillin↗

PubMed1978

The comparative synergistic activity of amikacin, gentamicin, netilmicin and azlocillin, mezlocillin, carbenicillin and ticarcillin against Serratia marcescens.

The synergistic activities of netilmicin, gentamicin and amikacin combined with carbenicillin, ticarcillin, azlocillin and mezlocillin were investigated against 32 Serratia marcescens isolates. Synergy could be demonstrated by killing curve technique, isobologram plots as susceptibility data with any of the aminoglycosides and penicillins combinations. No antagonism was shown with any of the combinations. The majority of the isolates were resistant to the aminoglycosides and penicillins. Combination of either ureido-penicillin or carbenicillin with gentamicin or netilmicin did not reduce the MIC values to levels achievable in serum but did reduce the MIC levels of both agents to those achievable in urine. The combination of ureido-penicillins or carbenicillin and ticarcillin with amikacin reduced the inhibitory levels of all isolates to levels achievable in both serum and urine.

Amikacin↗

PubMed1978

1-N HAPA gentamicin B, a new aminoglycoside active against gentamicin resistant isolates--activity compared to other aminoglycosides.

1-N HAPA gentamicin B is a new aminoglycoside active against most Enterobacteriaceae, Pseudomonas aeruginosa and Staphylococcus aureus. Among 504 clinical isolates at a concentration of 12.5 microgram/ml all Staph. aureus, Escherichia coli, Klebsiella, Enterobacter, Proteus rettgeri, Providencia and 78% of Pseudomonas, 86% of Proteus morganii were inhibited. Like other aminoglycosides, the activity was greatest at an alkaline ph and reduced by high cations concentrations. 1-N HAPA gentamicin B was equal in activity to amikacin against both gentamicin-sensitive and resistant isolates. It inhibited bacteria containing many of the aminoglycoside inactivating enzymes. When combined with carbenicillin it inhibited in a synergistic manner many Gram-negative bacteria, particularly Pseudomonas and Serratia.

Aminoglycosides↗

PubMed1976

In vitro synergistic effect of netilmicin, a new aminoglycoside antibiotic.

The combination of netilmicin (Sch 20569) with carbenicillin, cefazolin, chloramphenicol, and clindamycin was evaluated by in vitro tests against 91 clinical isolates of Pseudomonas, Klebsiella, and Escherichia coli. Combinations were considered to show synergy if there was a fourfold or greater reduction in minimal inhibitory concentration values of both antibiotics when combined. Synergy of netilmicin with carbenicillin could be demonstrated against 21 of 46 Pseudomonas isolates. Comparison of the synergy of carbenicillin with netilmicin or gentamicin showed that netilmicin was less active than gentamicin against Pseudomonas aeruginosa. However, at therapeutic concentrations of the antibiotics, significant differences were not observed. Synergy of netilmicin and cefazolin was demonstrated against only 1 of 21 Klebsiella strains tested, but partial synergy was found for 12 of 20 isolates. Synergy and antagonism were uncommon with the netilmicin-chloramphenicol and netilmicin-clindamycin combinations against E. coli and Pseudomonas.

Anti-Bacterial Agents↗

PubMed1976

In vitro study of netilmicin compared with other aminoglycosides.

Netilmicin (Sch 20569) is an ethyl derivative of gentamicin C(1a) that is active against most Enterobacteriaceae, Pseudomonas aeruginosa, and Staphylococcus aureus isolates. Among 342 clinical isolates tested, all staphylococci; 92% of Escherichia coli, 93% of Klebsiella pneumoniae, and 92% of Enterobacter were inhibited by 0.8 mug or less of netilmicin per ml, but only 78% of P. aeruginosa were inhibited by 3.1 mug or less per ml. Most clinical isolates of enterococci, Serratia marcescens, and Providencia were not inhibited by 3.1 mug of netilmicin per ml. Like other aminoglycosides, the netilmicin in vitro activity was markedly influenced by the growth medium used, with activity decreased by sodium, calcium, and magnesium. Netilmicin was more active at alkaline pH. Addition of magnesium to Pseudomonas or Serratia pretreated with netilmicin produced inhibition of killing. Netilmicin was more active than gentamicin, sisomicin, tobramycin, or amikacin against E. coli and K. pneumoniae. Netilmicin inhibited growth of all gentamicin-resistant isolates of Klebsiella and Citrobacter tested, but only 73% of E. coli; Pseudomonas and Providencia were resistant to netilmicin. Most Serratia (95%) and indole-positive Proteus (83%) isolates were resistant to netilmicin but were inhibited by amikacin.

Amikacin↗

PubMedDate not supplied

The postantibiotic suppressive effect of L-ofloxacin, an optically active isomer of ofloxacin.

The postantibiotic suppressive effect (PAE) of L-ofloxacin was studied and compared with those of ciprofloxacin and norfloxacin. The PAE of L-ofloxacin was observed against all Gram-positive organisms tested: Staphylococcus aureus, S. epidermidis, and Enterococcus faecalis. At the achievable serum concentrations L-ofloxacin showed a longer PAE than ciprofloxacin and norfloxacin. Exposure of organisms to 4 micrograms/ml of L-ofloxacin for 2 hr produced a 3.1 and 4.2 hr PAE for methicillin-sensitive and methicillin-resistant staphylococci, respectively. Against E. faecalis and S. epidermidis, the PAEs of L-ofloxacin were 1.9 and 1.6 hr, respectively.

Ciprofloxacin↗

PubMedDate not supplied

In vitro activity of levofloxacin, ofloxacin and other quinolones against coagulase-negative staphylococci.

The in vitro activity of levofloxacin against coagulase-negative staphylococci (CNS) was investigated. In vitro, on the basis of MIC90 values, levofloxacin was as active as ciprofloxacin, inhibiting both methicillin-sensitive and -resistant staphylococci at 0.5 microgram/ml. The frequency of one-step development of levofloxacin-resistant CNS was < 1 x 10(-9). After repeated transfer of CNS in the presence of increasing concentrations of levofloxacin or other quinolones, there were 4-fold increases in MIC50 values for both levofloxacin and ofloxacin, whereas there were 64- to 128-fold increases for ciprofloxacin, norfloxacin and enoxacin. Based on MIC50 values, the concentrations of 1 or 2 micrograms/ml are clinically relevant. The mutant strains induced by levofloxacin showed less virulence based on the LD50 value in acute systemic murine infection.

Animals↗