Comparative antimicrobial activity of ABT-773, a novel ketolide, tested against drug-resistant Gram-positive cocci and Haemophilus influenzae

Investigational new drugs for the treatment of resistant pneumococcal infections

Antibiotic resistance in Streptococcus pneumoniae is not only increasing with penicillin but also with other antimicrobial classes including the macrolides, tetracyclines and sulfonamides. This trend with antibiotic resistance has highlighted the need for the further development of new anti-infectives for the treatment of pneumococcal infections, particularly against multi-drug resistant pneumococci. Several new drugs with anti-pneumococcal activity are at various stages of development and will be discussed in this review. Two new cephalosporins with activity against S. pneumoniae include ceftobiprole and RWJ-54428. Faropenem is in a new class of beta-lactam antibiotics called the penems. Structurally, the penems are a hybrid between the penicillins and cephalosporins. Sitafloxacin and garenoxacin are two new quinolones that are likely to have a role in treating pneumococcal infections. Oritavancin and dalbavancin are glycopeptides with activity against methicillin-resistant S. aureus and vancomycin-resistant Enterococcus spp. as well as multi-drug resistant pneumococci. Tigecycline is the first drug in a new class of anti-infectives called the glycycyclines that has activity against penicillin-resistant pneumococci.

Telithromycin

Telithromycin, the first member of the ketolide antibacterials, has good activity against community-acquired respiratory pathogens, including multiple-drug-resistant strains of Streptococcus pneumoniae. Telithromycin 800 mg once daily has been US FDA approved for the treatment of acute bacterial sinusitis (ABS; treatment duration 5 days), acute bacterial exacerbations of chronic bronchitis (AECB; 5 days) and mild-to-moderate community-acquired pneumonia (CAP; 7-10 days). In patients with CAP, telithromycin was as effective as amoxicillin 1000 mg three times daily for 10 days, clarithromycin 500 mg twice daily for 10 days or trovafloxacin 200 mg once daily for 7-10 days. In patients with AECB, telithromycin was as effective as a 10-day regimen of amoxicillin/clavulanic acid 500/125 mg three times daily, cefuroxime axetil 500 mg twice daily or clarithromycin 500 mg twice daily. In patients with ABS, telithromycin was as effective as a 10-day course of amoxicillin/clavulanic acid 500/125 mg three times daily or cefuroxime axetil 250 mg twice daily. Telithromycin was generally well tolerated and most adverse events were of mild-to-moderate severity and transitory. The most common adverse events with telithromycin were diarrhoea and nausea (10.8% and 7.9% of 2702 patients in clinical trials); these events occurred in 8.6% and 4.6% of 2139 comparator-treated patients.