beta-Lactamase susceptibility and comparative activity of Sch 34343 and other beta-lactams for non-fermenters, Neisseria spp. and beta-lactamase-positive Enterobacteriaceae.

By means of a micro-dilution technique (10(5) cfu/cup) 30 strains of Pseudomonas spp. were found resistant to Sch 34343. The susceptibility of Acinetobacter spp. (20 strains) was greatest for imipenem, followed by Sch 34343 (MIC approximately 0.7 mg/l), ceftazidime and ceftriaxone. Ten Moraxella strains were very susceptible to Sch 34343, imipenem and ceftazidime. For 35 strains of Neisseria gonorrhoeae (ten beta-lactamase-positive) and ten strains of N. meningitidis we noted no resistance to Sch 34343 (MIC 0.015-0.06 mg/l), or to any of the other drugs tested. Sixty-two strains of Enterobacteriaceae producing various beta-lactamases were tested for their sensitivity to Sch 34343 and seven other beta-lactams. To an even greater extent than imipenem and Sch 34343, latamoxef and ceftazidime proved very active against all these strains. A PSE-4-producing Escherichia coli strain was resistant to Sch 34343. The inoculum effect (10(6) vs 10(4) cfu/ml) on Sch 34343 activity was usually small (1-4). Tests for the beta-lactamase susceptibility of Sch 34343 showed that only one PSE-3, one PSE-4 and one chromosomal beta-lactamase from a strain of Enterobacter cloacae were slightly active.