Activity Of Cephalothin Research Articles

Improvement of antibacterial efficacy using antibiotic encapsulated silica-containing redox nanoparticles

Purpose: Improving solubility and antibacterial efficiency of cephalothin by using silica-containing redox nanoparticle (siRNP) as a system to encapsulate and deliver this hydrophobic antibiotic.
 Methods: siRNP was synthesized by assembling amphiphilic block copolymers possessing a reactive oxygen species scavenging nitroxide radical and drug absorptive silica moieties in a hydrophobic side chain. Cephalothin, a hydrophobic antibiotic, was encapsulated into siRNP (cephalothin@siRNP) by mixing and dialysis methods. Antibacterial activity of cephalothin@siRNP against Staphylococcus aureus (S. aureus) và Escherichia coli (E. coli) was evaluated by the agar diffusion method.
 Results: The average size of siRNP and cephalothin@siRNP was 43.83 nm and 50.15 nm, respectively. After encapsulation in siRNP, the solubility of cephalothin was improved compared to cephalothin in an aqueous solution. The result showed that in vitro antibacterial activities of cephalothin and cephalothin@siRNP had no statistical difference after 24 h incubation on agar plates on both S. aureus and E. coli. However, after an extended incubation time, regrowth of E. coli colonies in the inhibitory zone was found in cephalothin treated plate. Interestingly, E. coli regrowth was significantly reduced in plates treated with cephalothin@siRNP.
 Conclusion: In this study, siRNP successfully encapsulated cephalothin and enhanced the solubility of this drug. The antibacterial activity of cephalothin is prolonged when encapsulated in siRNP, which suppressed the reccurrence of E. coli colonies. Cephalothin@siRNP has the potential to inhibit antibiotic resistance.

Synthesis and Antibacterial Activity of Metal Complexes of Cephalothin

The interactions of cephalothin (Hcephalo) with transition metal(II) ions and imidazole have been investigated. The complexes [M(cephalo)Cl], (where M=Mn(II), Co(II), Ni(II), Pd(II)) and [M(cephalo)(Im)Cl] (where M=Ni(II), Cu(II), Zn(II), Im=Imidazole) were obtained and characterized by physicochemical and spectroscopic methods. The IR and the 1H-NMR spectra of the complexes suggest that the cephalothin behaves as a monoanionic tridentate ligand. They have been screened for antibacterial activity against several bacteria, and the results are compared with the activity of cephalothin.

The antibacterial activity of a siderophore

The in vitro activity of deferoxamine (DFO) both per se and in combination with the reductant ascorbic acid (AA) was determined against 10 E. coli strains, 5 P. mirabilis strains, and 10 coagulase‐negative staphylococci. In terms of interaction, the influence of DFO on the activities of cephalothin and gentamicin was furthermore investigated against the same panel of strains employing a macrobroth dilution technique and killing‐curve kinetics. The MICs of cephalothin and gentamicin were lowered for one half of the strains. Moreover, DFO prolonged the generation times of logarithmic growth phase considerably, especially when the reductant AA was present. The interactions between DFO or DFO + A A and subinhibitory concentrations of antibiotics were established by the application of growth constants, and resulted in synergy for 15 out of 25 strains with cephalothin and 9 out of 25 strains with gentamicin.

In vitro Activity of Daptomycin against 297 Staphylococcal Isolates

The in vitro activity of daptomycin against 297 clinical isolates of Staphylococcus aureus and S. epidermidis sensu strictu was compared with the activities of cephalothin, dicloxacillin, tobramycin, and vancomycin. Minimal inhibitory concentrations (MICs) were determined by an agar dilution method. Cephalothin and dicloxacillin showed the highest activity against S. aureus on a weight-for-weight basis, all isolates being inhibited by 0.5 mg/l or less of either agent. Cephalothin was somewhat more active against S. epidermidis than was dicloxacillin. Daptomycin and vancomycin exhibited high and similar activity against both S. aureus and S. epidermidis (MIC90% = 1 and 2 mg/l, respectively). Tobramycin was highly active against S. aureus, but the activity against S. epidermidis was greatly variable (MIC range less than or equal to 0.03 - greater than or equal to 16 mg/l). The activity of daptomycin was markedly influenced by the test medium; the MICs were generally 32 times higher when the isolates were tested on Iso-Sensitest agar than on Mueller-Hinton agar. Supplementation of Iso-Sensitest agar with increasing concentrations of calcium potentiated the activity of daptomycin substantially, the results obtained on Iso-Sensitest agar supplemented with 20 mg Ca2+/l being similar to those obtained on Mueller-Hinton agar.

Growth responses of Vibrio cholerae biotype eltor and Escherichia coli under the presence of bile acid and antibiotics

The present experiments were performed to investigate the influence of bile acid and antibiotics on the growth of Vibrio cholerae biotype eltor and Escherichia coli.One strain of V. cholerae and two strains of E. coli which were different in sensitivity to antibiotics, were tested in vitro separately and together under the presence of sodium desoxycholate DC) and antibiotics. DC was used at a concentration similar to that in the human (small intestine. Six antibiotics were separately added at minimum inhibitory concentration (MIC) against V. cholerae.The results were as follows:1) DC easily inhibited V. cholerae. When a large number of E. coli was added, the inhibition increased.2) E. coli was a little inhibited by DC. But when a small number of E. coli was cultured with V. cholerae, E. coli was inhibited by the presence of V. cholerae regardless the presence of DC.3) DC strongly enhanced the antibacterial activity of ampicillin (ABPC), cephalothin (CET) and amikacin sulfate (AMK) against V. cholerae with increasing DC concentration, but had little effect on tetracycline (TC). The influence of DC on polymyxin B (PLB) and colistin (CL) varied with DC concentrations.4) DC slightly enhanced the antibacterial activity of ABPC, CET and AMK against the sensitive strain of E. coli with increasing DC concentration, but had little effect on TC, PLB and CL. DC had no influence on all six antibiotics against the resistant strain of E. coli.5) In the mixed culture of V. cholerae and a large number of E. coli, the antibacterial activity of ABPC, CET, AMK, and PLB against V. cholerae decreased as compared with that in a single culture. But DC inhibited the decrease.6) The resistance to ABPC and CET transferred from resistant strain of E. coli to V. cholerae. DC inhibited the transfer of resistance to ABPC with increasing DC concentration, and completely inhibited that of resistance to CET, regardless of DC concentration.

In vitro activity of N-formimidoyl thienamycin (MK0787), a crystalline derivative of thienamycin

N-Formimidoyl thienamycin (MK0787) is a derivative of thienamycin, a unique, new beta-lactam antibiotic. Its activity against 285 aerobic and facultatively anaerobic clinical isolates was compared with the activities of cephalothin, ampicillin, penicillin G, ticarcillin, and tobramycin. All of the 285 isolates, with the exception of 1 Staphylococcus epidermidis isolate, were inhibited by a concentration of N-formimidoyl thienamycin of less than or equal to 8 micrograms/ml. More than 50% of all isolates were inhibited by the lowest concentration of N-formimidoyl thienamycin tested (0.125 micrograms/ml); 98% of Staphylococcus aureus and 80% of S. epidermidis isolates were inhibited by N-formimidoyl thienamycin at a concentration of 0.125 micrograms/ml. Only 2 of 45 enterococci were not inhibited by 1 microgram of N-formimidoyl thienamycin per ml, and this drug was the most active agent tested against 162 gram-negative bacilli. It inhibited more than 95% of the gram-negative isolates at a concentration of less than or equal to 2 micrograms/ml. N-Formimidoyl thienamycin was as active or more active than tobramycin against Escherichia coli, Pseudomonas aeruginosa, and Proteus mirabilis and substantially more active than ticarcillin. All 16 isolates of Klebsiella pneumoniae were inhibited by less than or equal to 0.5 micrograms of N-formimidoyl thienamycin per ml. The marked in vitro activity of this drug against a wide variety of clinical isolates makes it a promising new antibiotic.

Penetration of Cephalothin and Cefoxitin into Experimental Infections with Bacteroides fragilis

The in vitro activities of cephalothin and cefoxitin against Bacteroides fragilis were studied by time-kill curves and measurement of residual drugs in culture supernatants. Cefoxitin was bactericidal, causing a decrease of 10(7) in viable counts over 24 hr. Cephalothin caused an initial decrease of 10(2) B. fragilis at 2 hr; this change was followed by growth of the organism within 24 hr back to the number present before addition of cephalothin. The concentration of cephalothin in broth decreased rapidly within 2 hr and was undetectable within 24 hr, whereas the level of cefoxitin decreased only 25% over the 24-hr period. Penetration of these drugs into perforated ping pong balls implanted intraperitoneally in rabbits was studied. Three weeks after implantation the reservoirs were infected with B. fragilis. After intramuscular administration of five doses of antibiotic, the penetration of cephalothin, as measured by bioassay, in uninfected and infected capsules was 16% and 2%, respectively, of the peak serum concentration; similar findings were noted with cefoxitin. For determination of the rate of breakdown within the infected site, radiolabeled antibiotic was injected into the capsule, and the concentrations of bioactive and radioactive drug were determined. With radiolabeled cephalothin there was a rapid decrease in bioactivity during the initial 60 min, and no active drug was measurable after 2 hr. In contrast, only 40% of cefoxitin was inactivated at the end of 6 hr. The results indicate that levels of cephalothin and cefoxitin are reduced significantly in sites infected with B. fragilis. The decrease appears to be mediated by both a decrease in penetration and inactivation at the site of infection.

Microbiological properties of a new cephalosporin, BL-S 339: 7-(phenylacetimidoyl-aminoacetamido)-3-(2-methyl-1,3,4-thiadiazol-5-ylthiomethyl)ceph-3-em-4-carboxylic acid.

BL-S 339 is a new broad-spectrum, parenterally effective cephalosporin whose expression of antibacterial activity in vitro is markedly affected by the nature of the assay medium. When assayed in nutrient agar, BL-S 339 was more active than cephalothin against strains of Diplococcus pneumoniae, Streptococcus pyogenes, Escherichia coli, Serratia marcescens, Klebsiella pneumoniae, Enterobacter, and indole-positive Proteus sp. However, when assayed in Mueller-Hinton medium, its activity, especially against gram-negative bacteria, was reduced substantially, whereas the activity of cephalothin was virtually unaffected by the assay medium. The in vivo activity of BL-S 339 correlated well with its activity in nutrient agar; when administered subcutaneously to mice, it was therapeutically more efficacious than cephalothin in infections caused by both gram-positive and gram-negative bacteria. When BL-S 339 was administered intramuscularly to mice, the concentrations achieved in the blood were three times those achieved with cephalothin. BL-S 339 was bound to human serum proteins to the same extent as cephalothin. Recovery of BL-S 339 in the urine within the 24-hr period after intramuscular administration to rats was three times that of cephalothin.