Resistance of anaerobic bacteria to antimicrobial agents in Spain.

As a consequence of antibiotic consumption, the entire microbial ecosystem attached to man is evolving towards resistance. In Spain, penicillin resistance (MIC > 0.5 mg/l) is found in about 10% of Peptostreptococcus, Clostridium perfringens and Eubacterium, and in 50% of Veillonella. Cefoxitin resistance ( > 2 mg/l) is present in 10 to 20% of Peptostreptococcus and Clostridium, and in 50% of Eubacterium; 21% of Bacteroides (fragilis group) strains are resistant to 16 mg/l. A very low rate of imipenem resistance (> or = 128 mg/l) is found among Bacteroides (1%), but for 5% of the isolates MICs of imipenem are 2 to 4 mg/l. Metronidazole resistance ( > 8 mg/l) is found in 5 to 10% of Peptostreptococcus, Clostridium and Veillonella, and in less than 1% of the Bacteroides fragilis group. Erythromycin resistance ( > 2 mg/l) is present in over two-thirds of the Peptostreptococcus, Veillonella and Fusobacterium isolates, and in 27% of the Clostridium perfringens strains. Clindamycin resistance ( > 4 mg/l) is found in 10 to 20% of the Peptostreptococcus, Clostridium and Eubacterium isolates, and in 20% of the Bacteroides of the fragilis group, this rate being higher (30%) among faecal isolates.