In vitro activity of midecamycin diacetate, a 16-membered macrolide, against Streptococcus pyogenes isolated in France, 1995-1999.

OBJECTIVE: To compare the in vitro activity of midecamycin diacetate to that of five other macrolides (erythromycin, clarithromycin, roxithromycin, azithromycin, and josamycin) and of clindamycin against 146 clinical isolates of Streptococcus pyogenes, with regard to three different phenotypes of erythromycin resistance. METHODS: Susceptibility pattern and resistance phenotype were determined by disk diffusion method and double disk test. Minimal inhibitory concentrations of antibiotics were obtained by the agar dilution method and evaluated according to the recommendations of the 'Comité de l'Antibiogramme de la Société Française de Microbiologie' (CA-SFM). The major determinants of erythromycin resistance in S. pyogenes (ermB, ermTR and mefA genes) were investigated by specific amplification protocols. RESULTS: Most of the isolates of S. pyogenes collected during 1995-99 were susceptible to midecamycin (93.8%), erythromycin (90.4%), clarithromycin (93.2%), roxithromycin (91.8%), azithromycin (88.4%), josamycin (94.5%), and clindamycin (94.5%). According to the CA-SFM criteria, 132 of the 146 isolates studied were susceptible to erythromycin (MICs < or = 1 mg/L), four were intermediate (MICs 2-4 mg/L), and 10 were resistant (MICs > 4 mg/L). Only nine isolates were midecamycin resistant (MICs > 4 mg/L), and the others were susceptible. The increased activity of midecamycin (MIC90 < or = 0.06 mg/L), as compared to erythromycin (MIC90 = 0.5 mg/L) and to other 14- or 15-membered macrolides, was related to the absence of the ermB determinant in seven isolates which displayed an efflux phenotype (five isolates) or an inducible resistance phenotype due to an ermTR determinant (two isolates). CONCLUSION: Midecamycin diacetate is active against most S. pyogenes strains isolated in France and may represent an attractive alternative to the treatment of streptococcal infections due to resistant isolates with efflux of erythromycin.

Antimicrobial prophylaxis for major head and neck cancer surgery with piperacillin and ornidazole.

A prospective study in 53 eligible patients, undergoing major head and neck cancer surgery was carried out to assess the combination of an ureido penicillin, piperacillin with a nitro imidazole agent, ornidazole, in order to prevent post-operative general and wound infections. Both antibiotics were administered for five days. Each patient had piperacillin 4 gm every eight hours and ornidazole 1 gm every 24 hours. The overall rate of infections was 13.2 per cent (n = 7), with 3.8 per cent (n = 2) wound infections and 11.3 per cent (n = 6) general infections (one patient presented both complications). There was no wound infection in the total surgery group (n = 12). General infections who only consisted of pneumonias were respectively 12.2 per cent (n = 5) in the group with partial procedures (n = 41) and 8.3 per cent (n = 1) in the total surgery group. This antibioprophylaxis can be recommended in major oncological neck surgery, specially in the case of partial procedures.