In vitro and in vivo activities of LB10522, a new catecholic cephalosporin

Pilot study of ampicillin-ceftriaxone combination for treatment of orthopedic infections due to Enterococcus faecalis

Serious Enterococcus faecalis infections usually require combination therapy to achieve a bactericidal effect. In orthopedic infections, the prognosis of enterococcal etiology is considered poor, and the use of aminoglycosides is questioned. The ampicillin-ceftriaxone combination has recently been accepted as alternative therapy for enterococcal endocarditis. After one of our patients with endocarditis and vertebral osteomyelitis was cured with ampicillin-ceftriaxone, we started a pilot study of orthopedic infections. Patients with infections due to E. faecalis (with two or more surgical samples or blood cultures) diagnosed during 2005 to 2008 were recruited. Polymicrobial infections with ampicillin- and ceftriaxone-resistant microorganisms were excluded. Patients received ampicillin (8 to 16 g/day)-ceftriaxone (2 to 4 g/day) and were followed up prospectively. Of 31 patients with E. faecalis infections, 10 received ampicillin-ceftriaxone. Including the first patient, 11 patients were treated with ampicillin-ceftriaxone: 3 with prosthetic joint infections, 3 with instrumented spine arthrodesis device infections, 2 with osteosynthesis device infections, 1 with foot osteomyelitis, and 2 with vertebral osteomyelitis and endocarditis. Six infections (55%) were polymicrobial. All cases except the vertebral osteomyelitis ones required surgery, with retention of foreign material in six cases. Ampicillin-ceftriaxone was given for 25 days (interquartile range, 15 to 34 days), followed by amoxicillin (amoxicilline) being given to seven patients (64%). One patient with endocarditis died within 2 weeks (hemorrhagic stroke) and was not evaluable. For one patient with prosthesis retention, the infection persisted; 9/10 patients (90%) were cured, but 1 patient was superinfected. Follow-up was for 21 months (interquartile range, 14 to 36 months). Ampicillin-ceftriaxone may be a reasonable synergistic combination to treat orthopedic infections due to E. faecalis. Our experience, though limited, shows good outcomes and tolerability and may provide a basis for further well-designed comparative studies.

In vitro antimicrobial activity of RU-59863, a C-7 catechol substituted cephalosporin

The in vitro activity of RU-59863, a so-called "fifth generation" catechol cephalosporin, was evaluated against 606 bacterial isolates and compared with the activities of cefotaxime, ceftazidime, cefepime, and cefpirome. RU-59863 demonstrated a broad spectrum of inhibition and superior overall activity than comparators when tested against Enterobacteriaciae (MIC90s, 0.015 to 2 micrograms/ml), Pseudomonas aeruginosa (MIC90, 0.5 microgram/ml), Stenotrophomonas maltophilia (MIC90, 0.25 microgram/ml), Acinetobacter ssp. (MIC90, 4 micrograms/ml), and oxacillin-susceptible Staphylococcus ssp. (MIC90s, 0.5 to 8 micrograms/ml). Potent RU-59863 activity was also observed against beta-haemolytic and viridans gr. streptococci (MIC90s, 0.12-0.5 microgram/ml), Streptococcus pneumoniae (MIC90s, 0.03 to 0.5 microgram/ml), Haemophilus influenzae (MIC90, 0.06 microgram/ml), and Neisseria gonorrhoeae (MIC90, 0.06 micrograms/ml). RU-59863 demonstrated marginal potency against Enterococcus faecalis (MICs 2 to 16 micrograms/ml) and was inactive against Enterococcus faecium (MIC90, > 128 micrograms/ml). Oxacillin-resistant staphylococci were not inhibited by RU-59863 (MIC90s, 32 to 128 micrograms/ml). Among the cephalosporins tested, RU-59863 performed best versus ceftazidime-resistant Bush group 1 isolates and strains producing extended spectrum beta-lactamases. RU-59863 was also effective against many fluoroquinolone-, aminoglycoside-, and imipenem-resistant isolates. RU-59863 seems to be a significant advance in cephalosporin chemistry and activity, especially against Gram-negative pathogens resistant to current beta-lactam therapeutic agents. Further studies of human pharmacokinetics and against clinical infections are encouraged.