In vitro activity of six beta-lactam antibiotics against non-beta-lactamase producing and producing enterobacteria and antibiotic resistance transfer.

beta-Lactamase production was evaluated by chromogenic cephalosporin 87/312 in 184 enterobacteria isolated from clinical sources. Minimal inhibitory concentrations (MICs) of six beta-lactam antibiotics (Ampicillin, Cephaloridine, Cephalexine, Cefazoline, Cefuroxime, Cefotaxime) were determined on 90 non beta-lactamase producing and 94 beta-lactamase producing strains by a miniaturized dilution method. beta-lactamase production transfer and antibiotic resistance transfer were observed in a receiving E.

Comparative activity of ceftazidime and four other cephalosporins against gram-negative bacteria and their sensitivity to beta-lactamases.

The in vitro activity of ceftazidime compared with other beta-lactamase stable compounds was assessed against recent Gram-negative isolates. Three hundred forty-three bacterial strains were isolated from patients affected with UTI, identified by standard bacteriological methods and investigated for their production of beta-lactamases by the Nitrocefin test. MICs and MBCs (minimum inhibitory concentrations and minimum bactericidal concentration) of ceftazidime, cefamandole, cefoxitin, cefotaxime and cefuroxime were determined by a miniaturized dilution broth method against all beta-lactamase producing bacteria (129 out of 343).

Comparative in vitro activity of norfloxacin and four other chemotherapeutics against urinary gram-negative isolates.

Three hundred seventy-five Gram-negative bacterial strains were isolated from urine specimens of as many patients affected by symptomatic or asymptomatic urinary tract infections. Susceptibility of bacteria to five chemotherapeutics (norfloxacin, oxolinic acid, pipemidic acid, nalidixic acid and nitrofurantoin) was studied determining minimum inhibitory concentrations (MICs) and minimum bactericidal concentrations (MBCs) of each compound by a miniaturized dilution broth method. Norfloxacin, a quinoline carboxylic acid compound structurally related to nalidixic acid, showed a much higher antibacterial activity against all bacterial strains under examination including Pseudomonas sp.