[Study of clinical bacteriological efficacy in a cefmenoxime ototopical solution]

Abstract

One percent cefmenoxime (CMX) ototopical solution was administered to 302 patients with purulent otitis media and acute diffuse external otitis in open study fashion, and to 216 patients with purulent otitis media in double blind condition. From among the total of 518 cases various bacteria were detected, except 22 of negative detection after incubation and 3 of impossible determination. The main bacteria detected from the above 493 cases were S. aureus (242 strains = 49.1%), P. aeruginosa (105 strains = 21.3%), S. epidermidis (67 strains = 13.6%), Proteus spp. (indole positive) (31 strains = 6.3%) and P. mirabilis (24 strains = 4.9%) as well as anaerobic bacteria (26 strains = 5.3%). MIC of CMX against those bacteria detected was evaluated at 10(8) CFU/ml and 10(6) CFU/ml, respectively, up to the concentration of 800 micrograms/ml, with MIC of cefazolin (CEZ), chloramphenicol (CP) and fradiomycin (FRM) as the references. With respect to the antibacterial action of CMX against S. aureus, MIC50 of CMX was inferior to that of CEZ by 4-fold, but its MIC80 and MIC90 are almost equivalent to those of CEZ. These results were obtained because there existed relatively few CMX highly resistant strains, while more than 20% strains are said to resist cephem antibiotics. As far as MIC of CMX against P. aeruginosa was concerned, the MIC reached its peak with 100 micrograms/ml at the concentration of 10(8) CFU/ml and with 25 micrograms/ml at 10(6) CFU/ml, respectively, which indicated the real antibacterial value of CMX against P. aeruginosa. However, the strains which showed higher MIC of greater than 800 micrograms/ml were rather few, that is, only 8 out of 105 (7.6%). Antibacterial action of CMX against Streptococcus (except Enterococcus), GNR from intestinal bacteria and anaerobic bacteria was favorable, and the stable and strong antibacterial action was shown against C. freundii, Enterobacter spp., S. marcescens and Proteus spp. (indole positive) which produce chromosome mediated beta-lactamase. On the other hand, the antibacterial action of CMX against GNF-GNR except P. aeruginosa was unfavorable for P. cepacia, P. putida and A. xylosoxidans, but relatively favorable for A. calcoaceticus. As a result of MIC evaluation of reference drugs, S. aureus was resistant to CEZ, and Proteus spp. (indole-positive) was resistant to CP, while FRM was highly resisted by almost all strains of bacteria. However, the resistance rate of S. aureus to CP was relatively low, that is, as low as 16.1%.(ABSTRACT TRUNCATED AT 400 WORDS)