Cefuroxime: a new cephalosporin antibiotic with enhanced stability to enterobacterial beta-lactamases

Drug-Releasing Antibacterial Coating Made from Nano-Hydroxyapatite Using the Sonocoating Method

Medical implant use is associated with a risk of infection caused by bacteria on their surface. Implants with a surface that has both bone growth-promoting properties and antibacterial properties are of interest in orthopedics. In the current study, we fabricated a bioactive coating of hydroxyapatite nanoparticles on polyether ether ketone (PEEK) using the sonocoating method. The sonocoating method creates a layer by immersing the object in a suspension of nanoparticles in water and applying a high-power ultrasound. We show that the simple layer fabrication method results in a well-adhering layer with a thickness of 219 nm to 764 nm. Dropping cefuroxime sodium salt (Cef) antibiotic on the coated substrate creates a layer with a drug release effect and antibacterial activity against Staphylococcus aureus. We achieved a concentration of up to 1 mg of drug per cm² of the coated substrate. In drug release tests, an initial burst was observed within 24 h, accompanied by a linear stable release effect. The drug-loaded implants exhibited sufficient activity against S. aureus for 24 and 168 h. Thus, the simple method we present here produces a biocompatible coating that can be soaked with antibiotics for antibacterial properties and can be used for a range of medical implants.

Spectrofluorimetric analysis of cefuroxime in pharmaceutical dosage forms

A fluorimetric method has been developed for the quantitative analysis of cefuroxime, based upon the formation of a fluorescent derivative formed by alkaline hydrolysis with 1.0 M sodium hydroxide and heating at 100 degrees C for 60 min. The fluorescent product gave excitation and emission maxima at 380 and 436 nm, respectively. The method was performed in aqueous solution adjusted to pH 10.5 by addition of phosphate buffer solution. The calibration curve was found to be linear in the range of concentrations 0.050-1.70 micrograms ml-1. The lower limit of detection was 1.0 x 10(-2) micrograms ml-1. The method was applied to authentic pharmaceutical preparations containing cefuroxime sodium or cefuroxime axetil, the 1-(acetyloxy) ethyl ester of the drug, and was found to be satisfactory. Cefuroxime sodium was also determined in physiological solutions used to prepare intravenous infusions of this antibiotic.

Recognition and clinical significance of mechanisms of bacterial resistance to beta-lactams

Resistance to beta-lactams may be difficult to recognize. This is due to the difficulty in detecting these resistances, when the routine tests performed in diagnostic laboratories are interpreted in the usual manner. Since failure to recognize this type of resistance may have serious consequences for the patient, it is essential that it be detected when present. For the detection of methicillin resistance of Staphylococcus aureus a standardized method using either a medium containing 5% NaCl or a low incubation temperature is advocated. Methicillin resistance of S. epidermidis can only be recognized reliably by means of a quantitative test and incubation for 42-48 h. Resistance of Haemophilus influenzae to ampicillin may be intrinsic or it may be caused by a TEM beta-lactamase; a beta-lactamase test should be used to detect the latter type of resistance. Inducible cephalosporinase may be responsible for the rapid development of resistance of some bacterial species to cefamandole, even during therapy. If a stable beta-lactamase production is attained by mutation, resistance to other beta-lactams will usually be present as well. Routine induction tests should be performed for all isolates of species of Enterobacter, Serratia, Citrobacter and Proteus, indole-positive. The same type of 'hidden' resistance may be present in Pseudomonas aeruginosa, with regard to cefotaxime and other third-generation cephalosporins. Beta-lactamase-positive Neisseria gonorrhoeae can easily be recognized by a beta-lactamase test. In addition, the results of diffusion tests allow one to distinguish between beta-lactamase-positive and beta-lactamase-negative strains. Recognition of those strains of N. gonorrhoeae having a decreased susceptibility to penicillin is only possible when well-standardized quantitative tests are used.

Fluorimetric determination of cefuroxime in body fluids

A simple and accurate fluorimetric procedure for measuring cefuroxime in body fluids is described. A fluorescent product was produced by addition of hydrochloric acid, heating, and cooling, followed by addition of sodium hydroxide and further heating at 100 degree C. The fluorescence intensity of the final solution was measured in a fluorimeter at an excitation wavelength of 375 nm and an emission wavelength of 440 nm and related to the antibiotic concentration. Thin-layer chromatography of the final solution showed a single fluorescent spot (Rf value, 0.6). Freedom from interference from other therapeutic agents and endogenous substances, as well as the close correlation between this method and the standard microbiological assay method, was demonstrated. The simplicity and reliability of the fluorimetric assay method make it particularly suitable for clinical use.

A possible role of R plasmids in bacterial permeability for beta-lactam antibiotics

Four strains of clinical isolates of Serratia marcescens (13039, 13090, 13093, 14093) harboring R plasmids were highly resistant to ampicillin (ABPC) and cephaloridine (CER). With elimination of R plasmids from these strains by acriflavine treatment, ABPC-resistance levels of these strains were markedly reduced. Reduction of CER-resistance levels was also demonstrated in strains 13039 and 13093, but not in strains 13090 and 14093. The permeability of the former strains for CER was also decreased, but not in the latter strains. At the same time, beta-lactamase activity of these strains also almost completely disappeared when the R plasmids were eliminated. By broth matings with these strains. The recipient strains of S. marcescens 13031 (rif), Escherichia coli K-12 (rif), and E coli 15046 (rif) all acquired a high permeability barrier against CER with inheritance of the R plasmids from strains 13039 and 13093, but not from strains 13090 and 14093. The transconjugant of strain 13031 that inherited R plasmid 13093 was resistant not only to CER but also to cefazolin, cephalothin, and cephalexin. Its permeability to these antibiotics was significantly lower than that of the original strain. This fact suggest the possibility that the R plasmid from strain 13093 may be involved not only in production of beta-lactamases, but also in regulation of bacterial permeability for cephalosporins.

A comparison of cefamandole, cefoxitin, cefuroxime, cefotaxime and cefoperazone: an in vitro test on a number of beta-lactamase producing strains of 9 species and 1 genus of bacteria

The sensitivity of a number of beta-lactamase producing strains of Enterobacter aerogenes, Enterobacter cloacae, Enterobacter species, Escherichia coli, Haemophilus influenzae, Klebsiella pneumoniae, Proteus mirabilis, Proteus vulgaris, Pseudomonas aeruginosa and Serratia marcescens to cefamandole, cefoxitin, cefuroxime, cefotaxime and cefoperazone was determined in vitro. All bacterial cultures were examined for beta-lactamase production using the chromogenic cephalosporin compound 87/312. All strains were typed by means of antibiotic and chemotherapeutic sensitivities. Only non-identical strains were used. A tray method was used to determine the quantity of antimicrobial product necessary for a complete growth inhibition at various culture dilutions. The results showed that all strains of H. influenzae, especially in the dilution 2.10(6), were sensitive to the five cephalosporins. The other species and genus of bacteria had a varying sensitivity to the five cephalosporins. Cefoperazone had potent activity against Ps. aeruginosa. Differences between the five cephalosporins with regard to the effect of culture dilution were only small.

Emergence of trimethoprim-resistant enterobacteria in patients receiving long-term co-trimoxazole for the control of intractable urinary-tract infection

In patients with previously intractable urinary-tract infection treated with low-dose co-trimoxazole for 6--58 (mean 32.7) months, the percentage of infected urines fell from 41.4 before treatment to 6.3 during treatment. Only 6 episodes of infection were due to trimethoprim-resistant bacteria. Results in a small group of patients in whom treatment was continued with trimethoprim alone were similar. Under the conditions of this study, long-term control of urinary-tract infection was not materially compromised by breakthrough infections due to trimethoprim-resistant organisms.

Susceptibility to beta-lactam antibiotics and production of beta-lactamase in Bacteroides fragilis

Using the agar dilution technique, 231 strains of Bacteroides fragilis, isolated during a 2-year period from human infections, were identified at subspecies level and were tested for susceptibility to 13 beta-lactam antibiotics. The penicillins were benzylpenicillin, ampicillin, carbenicillin, cloxacillin, and the recently described penicillin derivatives cyclacillin, ticarcillin, and PC-904. The following cephalosporin derivatives were tested: cephaloridine, cephalothin, cephalexin, cefamandole and cefuroxime. The cephamycin C derivative cefoxitin was also included in the study. Cefoxitin was the most effective drug tested since more than 80% of the strains were inhibited by 8 microgram/ml or less, and no strain had a minimal inhibitory concentration (MIC) of more than 64 microgram/ml. There was no marked difference in sensitivity among the subspecies with exception of subspecies vulgatus, which was slightly more sensitive to all antibiotics tested. The size of the inoculum was an important factor for obtaining reproducible results in the sensitivity tests. Increased inocula resulted in markedly higher MICs for cephaloridine and cefuroxime. Production of beta-lactamase was performed on all isolates by a chromogenic cephalosporin substrate and about 90% of the strains were found to be beta-lactamase producers.