Place of parenteral cephalosporins in the ambulatory setting: clinical evidence

Impact of hyperlipidaemia on the orbital bone cefotaxime levels in rats

Facial injuries are critical conditions, leading to serious complications, such as occult facial infections. Infectious endophthalmitis occurs despite of antibiotics use during implantation of intraocular lenses and is generally resistant to antibiotic therapy. It is a crucial situation in ophthalmology, since it often induces a substantial reduction of visual acuity and in some cases the loss of the eye despite treatment. It is, therefore, important to obtain drug levels able to exert antimicrobial effect in the diseased organ. The distribution of a drug depends on the binding extent to both plasma proteins and tissues and only the free drug is capable to be transported/diffused across membranes from blood vessels into tissues, in order to achieve its effect on the target organ. Hyperlipidaemia and consequent enhanced concentration of free fatty acid can modify binding pharmacokinetics of antibiotics through antagonism for the same binding sites. Cefotaxime, the third generation cephalosporin with easy penetration in a variety of tissues and body fluids and low incidence of adverse effects, can obtain adequate concentration in blood, eye bulb, and in the orbital bones. Its levels are influenced by hyperlipidaemia with clinical impact.

Cefotaxime kinetics in plasma and synovial fluid following intravenous administration in horses

Cefotaxime powder was diluted with sterile water to a concentration of 100 mg/mL. The volume of solution was adjusted for each experimental horse to provide a total dose of 15, 20, and 25 mg/kg and was administered by infusion through a jugular vein catheter over a 10-min period. All three doses were administered to each of the six experimental horses at three different times. Cefotaxime concentrations in plasma and synovial fluid samples were measured by high-performance liquid chromatography (HPLC). Standard compartmental analysis techniques and the WinSAAM modeling program were used to determine standard pharmacokinetic parameters for cefotaxime. The plasma and synovial fluid data from the five horses administered the 25 mg/kg dose was analyzed. Plasma cefotaxime concentrations appeared to be linearly related to dose infused and declined in parallel, suggesting linear drug kinetics. Moreover, cefotaxime concentrations declined monotonically suggesting that its disposition kinetics could essentially be described by a one-compartment model rather than the fact that sampling occurred after the infusion was discontinued. Maximum concentration of cefotaxime in plasma occurred immediately after cessation of the infusion. Minimum inhibitory concentrations were determined for Staphylococcus aureus, Escherichia coli, Pseudomonas aeruginosa, and Klebsiella pneumoniae, common isolates from septic arthritis in horses. Based on our pharmacokinetic data, a regimen of 25 mg/kg administered i.v. every 6 h appears appropriate for susceptible joint infections in adult horses.

Antibiotic susceptibility of bacteria most commonly isolated from bone related infections: the role of cephalosporins in antimicrobial therapy

Bone infections, which can be acute or chronic, often require aggressive antibiotic therapy, whether treated at home or in the community. Surveillance programmes are essential tools in the monitoring of antimicrobial resistance and can act as a resource to maintain effective prescribing. The Surveillance Network (TSN), which collects organism and patient-specific data from a network of laboratories across the United States, was used to analyse susceptibility of common bacterial species isolated from bone infections during 2000-2002. Narrow-spectrum antimicrobials such as vancomycin, quinupristin-dalfopristin and linezolid demonstrated good activity against Staphylococcus aureus and streptococci, and were active against 100% of isolates. However, Gram-negative species were also commonly isolated from these sites of infection. Later-generation cephalosporins, represented by ceftriaxone, cefotaxime and cefepime, exhibited a broad spectrum of activity including Enterobacteriaceae, streptococci and methicillin-susceptible S. aureus, but they were not active against methicillin-resistant S. aureus (MRSA) and showed variable activity against Pseudomonas aeruginosa. Using ceftazidime as a marker for extended spectrum beta-lactamase (ESBL) expression, less than 3% of Escherichia coli or Klebsiella pneumoniae expressed this phenotype. Based on current in vitro activity, the third-generation cephalosporins provide broad-spectrum coverage useful for the empirical therapy of suspected bone infections, especially for patients treated in the community or hospitalised with community-acquired infections.

Outpatient parenteral antimicrobial therapy (OPAT) for the treatment of osteomyelitis: evaluation of efficacy, tolerance and cost

OBJECTIVES

To evaluate the feasibility, efficacy, and cost of outpatient parenteral antimicrobial therapy (OPAT) in the treatment of osteomyelitis.

SUBJECTS

39 patients with an osteomyelitis requiring parenterally administered antibiotics for more than 4 weeks, and able to receive antibiotics at home.

METHODS

All patients had a totally implanted catheter. Antibiotics were administered by continuous infusion using a portable elastomeric infusion system, which was changed every day by the patient or by the home-care nurse. Laboratory monitoring and surveillance were performed weekly. Clinical efficacy, adverse effects and quality of life were recorded.

RESULTS

The most commonly used antibiotics were vancomycin (51%) and beta-lactam (44%) antibiotics. Thirty patients were available for follow-up for a minimum of 12 months after completion of therapy. Twenty-eight (93%) were considered cured of their infection with a mean of 24 +/- 4 months after completion of antibiotic therapy. Adverse effects among the study patients were rare. The 39 patients in our OPAT programme resulted in a potential saving of US $1 873 885 relative to conventional therapy.

CONCLUSION

OPAT is practicable and effective and may be the best alternative treatment for patients suffering from osteomyelitis requiring intravenous therapy.

[The comparative costs of vancomycin treatment versus teicoplanin in osteoarticular infection caused by methicillin-resistant staphylococci]

This clinical and economical study compared two glycopeptides regimen i.e., vancomycin and teicoplanin in the treatment of osteoarticular infection involving methicillin-resistant staphylococcus. After randomization, 15 patients (group 1) received vancomycin (23 F per gram) in continuous infusion through a central venous catheter and 15 others (group 2) intramuscular teicoplanin (311-357 F a 400 mg vial). The clinical study focused on treatment tolerance in an in-patient setting as well as in a non in-patient one. The cost analysis focused on total expenses including those of antibiotics, those of medical devices for antibiotic administration and those of the complications caused by the antibiotics use. Total expenses per patient averaged 8744 F with vancomycin and 8555 F with teicoplanin (NS). The apparent money saving by using a cheap antibiotic (i.e. vancomycin) was illusionary as one took in account the expenses for medical devices e.g., central venous catheters required to administer vancomycin and the complications due to the use of these devices.