Nozomu Kosakai

Changes of Antimicrobial Susceptibility of Anaerobic Bacteria from Clinical Specimen

The susceptibility to several commonly used antimicrobial agents was examined on approximately 900 isolates of various anaerobes from clinical specimens between October 1965 to May 1975, and the changes of susceptibility were investigated. Antimicrobial agents tested were penicillin G (PC-G), ampicillin (AB-PC), cephaloridine (CER), erythromycin (EM), josamycin (JM), lincomycin (LCM), clindamycin (CLDM), chloramphenicol (CP) and tetracycline (TC). And thiamphenicol (TP) and doxycycline (DOTC) were also used against recently isolated organisms. Minimal inhibitory concentrations (MIC) were determined with agar plate dilution method. The activity of PC-G, AB-PC and CER against almost all strains of anaerobes was good at 12.5 mug/ml or less, but a marked increase of resistant strains of Bacteroides was recognized. EM, JM and LCM had similar activity against anaerobes, and were effective to most strains of anaerobes except for Veillonella, Bacteroides and Fusobacterium. CLDM was highly active against almost all strains of anaerobes, and more active than the two macrolides and LCM. But recently, significant increase in resistant strains was observed among Bacteroides. CP had good activity against all strains of anaerobes, and the increase of resistant strains was not recognized. TP had a similar good activity as CP. While, activity of TC against all anaerobes was poor at the level of 25 mug/ml or more. DOTC was more active than TC against all strains tested.