Third-generation and investigational cephalosporins: II. Microbiologic review and clinical summaries

The Cephalosporin Antibiotic Agents — II. First- and Second-Generation Agents

The first article in this series discussed the cephalosporin antibiotic agents as a class, including the similarities in their structure, antimicrobial action, and toxicity. Part II focuses on the difference between commercially available first- and second-“generation” agents.

The cephalosporins are classified using various criteria, including vulnerability to beta-lactamase hydrolysis and antibacterial activity. The latter classification is based on the in vitro activity of the individual agents, with each succeeding “generation” possessing a greater spectrum of activity than the previous generation(s).

Electrocatalytic oxidation and determination of antibiotic in pharmaceutical samples on a nanostructure

A copper hexacyanoferrate nanostructure was prepared on the surface of a disposable pencil graphite electrode. The copper hexacyanoferrate nanostructures showed a pair of symmetric voltammetric peaks at 0.67 V/SCE. An electrochemical comparative characterization between copper hexacyanoferrate nano and bulk structures was presented. The transfer coefficient (α) and apparent charge rate constant (Ks) were evaluated for each of copper hexacyanoferrate nano and bulk structures. The resulting electrode exhibits an excellent electrocatalytic activity for the oxidation of ceftriaxone sodium. Cyclic voltammetry and chronoamperometry were employed to characterize the response to ceftriaxone sodium that changes linearly in the concentration range from 2 to 72 μM, with a detection limit of 0.54 μM (at a signal to noise ratio of 3). Typical features of the sensor include low cost, simple preparation, fast response, good stability, selectivity, and reproducibility. It was applied to the determination of ceftriaxone sodium in pharmaceutical samples. All results obtained were compared to the recommended procedure by British Pharmacopeia.

Adsorptive stripping voltammetric determination of cefepime at the mercury electrode in human urine and cerebrospinal fluid, and differential pulse polarographic determination in serum

The cephalosporin cefepime has been studied by adsorptive stripping voltammetric on the hanging mercury drop electrode, followed by linear sweep voltammetry (staircase). The adsorptive stripping response was evaluated with respect to preconcentration dependence and other variables. The drug is strongly adsorbed in acid media, with maximum adsorption at pH 5.8. The detection limit found was 4.8 x 10(-10) M, with 120-s preconcentration. The relative standard deviation at the 10(-7) M level was 0.93%. This method was applied to the determination of cefepime in human urine and cerebrospinal fluid. Differential pulse polarography has been applied to determination in human serum.

Voltammetric behavior of cefixime and cefpodoxime proxetil and determination in pharmaceutical formulations and urine

Electrochemical reduction behavior of cephalosporins, Cefixime (CF) and Cefpodoxime Proxetil (CP) have been studied by using different voltammetric techniques in Britton-Robinson buffer system. Two well defined cathodic waves are observed for both the compounds in the entire pH range. Number of electrons transferred in the reduction process was calculated and the reduction mechanism is proposed. The results indicate that the process of both the compounds is irreversible and diffusion-controlled. The peak currents for CF and CP are found to be linear over the range of concentration 6.0 x 10(-8) to 1.2 x 10(-5) mol l(-1) and 8.8 x 10(-8) to 1.1 x 10(-5) mol l(-1), respectively. The lower detection limits are found to be 4.6 x 10(-8) and 8.52 x 10(-8) mol l(-1) for the two compounds. A differential pulse voltammetric method has been developed for the determination of these drugs in pharmaceutical formulations and urine samples.

Electrochemical analysis of cephalosporin antibiotics

A review is presented on electroanalysis studies and methods for the determination of cephalosporin antibiotics in either simple solutions or biological fluids. Some general data about the electroactivity of cephalosporins are given and the analytical utilization of those data together with the corresponding analytical parameters, compiled from different literature sources.

A survey of antimicrobial prophylaxis in elective colorectal surgery in New Zealand

In 1988 a survey of New Zealand general surgeons was conducted, by post, on the subject of routine antimicrobial prophylaxis for elective colorectal surgery. Surgeons who gave routine prophylaxis were asked for details of their regimens; those who did not were asked for their reasons. One hundred and seventy-five questionnaires were distributed and 167 were returned. Of these, 124 came from surgeons with a colorectal practice, and 118 of the 124 surgeons satisfactorily completed the questionnaire. Routine antimicrobial prophylaxis was given by 96.6% (114 of 118). Of the 114 surgeons prescribing prophylaxis, one antimicrobial agent was used by 36.8%, two were employed by 53.5% and three or five were used by the remainder. The most commonly used (74.6%) antimicrobial agents were cephalosporins which were prescribed, alone or in combination with a nitroimidazole. The most frequent duration (46.4%) of antimicrobial administration was a combination of both the peri- and postoperative periods. When antimicrobial spectrum, route and duration of administration were all taken into account, 49.1% (56 of 114) were considered to give satisfactory regimens. Excessively protracted administration was the most frequent reason for unsatisfactory classification. The results of this survey demonstrate serious deficiencies in the practice of antimicrobial prophylaxis in elective colorectal surgery. These should be addressed through a programme of continuing education.

A team approach to reduce antibiotic costs

After partial success in reducing antibiotic drug costs by traditional methods (i.e., closed formulary, use of generic drugs, retrospective drug usage review, continuing education), a study of a new "team approach" was implemented. The study involved a clinical pharmacist and physicians working together to select the most appropriate antibiotic therapy. The clinical pharmacist reviewed the culture and sensitivity data and the pattern of infectious disease over the six-month period prior to the initiation of the study and prepared a list of the most appropriate antibiotics based on clinical efficacy and cost effectiveness. He then joined the physicians on morning rounds to monitor therapy and help in the selection of the most appropriate drug regimen. At the end of the study period, antibiotic cost savings of 58.6 percent were achieved.

Ceftriaxone. A reappraisal of its antibacterial activity and pharmacokinetic properties, and an update on its therapeutic use with particular reference to once-daily administration

Since ceftriaxone was first reviewed in the Journal, further studies have confirmed its broad antibacterial spectrum in vitro and extended its clinical documentation in comparative studies with other widely used drugs in infections of the urinary and lower respiratory tract, meningitis in infants and children, uncomplicated gonorrhoea, perioperative prophylaxis in patients undergoing surgery, and in several other types of infection. As in earlier studies, which primarily used a twice-daily dosage regimen, few significant differences were found between therapeutic groups in comparative studies and results have demonstrated the efficacy of once-daily ceftriaxone in all but the most serious infections, such as sole antibiotic therapy in pseudomonal infections. Wider clinical experience has established that ceftriaxone is generally well tolerated. Thus, ceftriaxone now has a well-defined place as an appropriate alternative for the parenteral treatment of a variety of infections due to susceptible organisms, as well as for perioperative prophylaxis of surgery, and may offer advantages of greater convenience over other parenteral antibiotics which are administered more frequently.

Cephalosporin, carbapenem, and monobactam antibiotics

Cephalosporin and related antibiotics are highly effective bactericidal agents of relatively low toxicity. The spectrum of activity varies with the drug but is usually broad. The first-generation cephalosporins, and especially cefazolin, are most active against sensitive staphylococci and streptococci. Most second-generation (except cefoxitin) and third-generation cephalosporins show substantial activity against Haemophilus influenzae. All cephalosporins (except cefsulodin) are active against Klebsiella, Escherichia coli, and Proteus mirabilis, whereas only the third-generation agents have pronounced activity against the other Enterobacteriaceae. Imipenem (a carbapenem) is active against essentially all pathogenic organisms, but aztreonam (a monobactam) is active against only aerobic gram-negative bacilli. Advantages associated with some of the new cephalosporins are once-daily administration and high cerebrospinal fluid levels. With the development of new cephalosporins, however, new toxicities have become apparent, and superinfections and induction of resistance have become greater problems. The cephalosporins are among the most expensive antibiotics in use today; thus, use of these expensive agents must be justified by lower toxicity, greater efficacy, or both in comparison with drugs of more reasonable cost.

Ceftriaxone: a beta-lactamase-stable, broad-spectrum cephalosporin with an extended half-life

Ceftriaxone is an aminothiazolyl-oxyimino cephalosporin. It possesses the typical in vitro activity of a third-generation cephalosporin with excellent activity against many gram-negative aerobic bacilli: Escherichia coli; species of Proteus, Klebsiella, Morganella, Providencia and Citrobacter; and Enterobacter agglomerans. Ceftriaxone also has outstanding bactericidal action against pneumococci, group B streptococci, meningococci, gonococci and Hemophilus influenzae. In healthy volunteers, it has an exceptionally long serum half-life of 5.8-8.7 (mean 6.5) hours. It distributes well throughout all body spaces, including cerebrospinal fluid in the presence of inflammation. Dosage modification is necessary only when there is combined hepatic and renal dysfunction. Adverse reactions characteristic of cephalosporins have been observed with the administration of ceftriaxone. No unique toxicities have been identified, and hypoprothrombinemic bleeding is not part of the adverse reaction profile. Ceftriaxone has been used to treat serious bacterial infections in neonates, infants, children and adults. Bacteriologic and clinical success rates have consistently exceeded 90%. The drug has also been used as single-dose chemoprophylaxis in coronary artery bypass, biliary tract, vaginal hysterectomy and prostatic surgery. Efficacy and safety were similar to multiple-dose cefazolin. Ceftriaxone warrants special consideration because its extended half-life allows for less frequent dosing than other antimicrobials. Significant cost savings can be realized with proper use of this antibiotic.

Antimicrobial activities of BMY-28142, cefbuperazone, and cefpiramide compared with those of other cephalosporins

The antimicrobial activities of BMY-28142, cefbuperazone (BMY-25182; formerly T-1982), and cefpiramide (WY-44635; formerly SM-1652) were compared with those of cefmenoxime, cefoperazone, cefotaxime, ceftizoxime, and moxalactam. BMY-28142 was the most active cephalosporin against the majority of aerobic and facultatively anaerobic microorganisms studied. Its spectrum of activity was very similar to that of cefotaxime. However, BMY-28142, cefbuperazone, cefmenoxime, cefotaxime, ceftizoxime, and moxalactam were equivalent in activity and rate of killing against members of the family Enterobacteriaceae. Cefpiramide was considerably less active than the other cephalosporins against the Enterobacteriaceae.

The cephalosporin antibiotic agents--III. Third-generation cephalosporins

The third-“generation” cephalosporin antibiotics (Table 1) represent a class of agents with an expanded gram-negative spectrum of activity beyond that of the first- and second-“generation” cephalosporins. Greater stability to beta-lactamases produced by gram-negative organisms confers to these agents a greater bactericidal action against the Enterobacteriaceae. Large bacterial inocula (105/ml) in vitro significantly increase the minimum inhibitory and bactericidal concentrations (MIC and MBC) explaining treatment failures with these agents in infections associated with large numbers of organisms. The pharmacokinetic features of some of the agents allow prolongation of dosing intervals, and enhanced tissue penetration amplifies their clinical utility in infections distant from the bloodstream (eg, meningitis).

Ceftazidime versus tobramycin/ticarcillin in treating hospital acquired pneumonia and bacteremia

Thirty-five patients in a neurosurgical intensive care unit who had nosocomial pneumonia and bacteremia were randomly assigned to receive either ceftazidime (Cef) or the combination of ticarcillin and pharmacokinetically adjusted doses of tobramycin (T/T). Fifteen of 17 patients (88%) who received Cef were cured or improved compared to 15 of 18 (83%) who received T/T. The original pathogen was eradicated from the respiratory secretion in 10 of 15 patients receiving Cef compared to only 6 of 18 patients receiving T/T (p = 0.12). All patients in both treatment groups who had positive blood cultures cleared the organism from the bloodstream. No cases of drug toxicity, including renal toxicity, were seen in either group. Cef used as a single agent in nosocomial pneumonias and bacteremias performed at least as well as T/T.

Penetration of cefoperazone into surgical wound drainage in patients undergoing head and neck surgery

Cefoperazone penetration into skeletal muscle and wound drainage in patients undergoing major surgery of the head and neck was measured by high-pressure liquid chromatography. Cefoperazone (2 g) was infused over 30 min before surgery and every 8 h for three postoperative doses. Simultaneous samples of serum and sternomastoid muscle were collected in 18 patients at 135 to 480 min after infusion. Mean cefoperazone concentrations in muscle tissue were 17.1% of those in simultaneously collected serum. Steady-state wound drainage concentrations after the fourth dose of cefoperazone averaged 55.2 micrograms/ml at 1 to 2 h and 62.1 micrograms/ml at 2 to 3 h. Simultaneous steady-state serum and wound fluid samples were obtained at regular intervals in six patients. In all patients, the peak level in wound fluid exceeded 25 micrograms/ml. Thus, cefoperazone reaches interstitial fluid concentration in soft tissue that exceeds the MICs required to inhibit the usual pathogens found at the site of wound infection after head and neck surgery.