In vitro antibacterial activity of norfloxacin and other agents against ocular pathogens.

302 clinical isolates representing 16 bacterial species most often implicated in ocular infections were tested in vitro against norfloxacin and a panel of antibacterial agents. On the basis of the 90% minimal inhibitory concentration (MIC90) data, norfloxacin was 4-32 times more active than the next best antimicrobial tested against Citrobacter freundii, Escherichia coli, Morganella morganii, Proteus mirabilis, Proteus vulgaris, Haemophilus influenzae, Neisseria gonorrhoeae and Staphylococcus epidermidis, with overall MIC90 less than or equal to 1 mg/l. Norfloxacin was equal in activity to polymyxin B against Klebsiella pneumoniae (MIC90 = 1 mg/l), and it ranked second to both polymyxin B against Pseudomonas aeruginosa and cotrimoxazole against Staphylococcus aureus, (MIC90 = 2 mg/l in each case). Along with neomycin and cotrimoxazole, norfloxacin (MIC90 = 1 mg/l) ranked second to gentamicin and tetracycline against Moraxella species. Compared to erythromycin (MIC90 less than or equal to 0.125 mg/l), norfloxacin (MIC90 less than or equal to 16 mg/l) was considerably less active against streptococci. Overall, norfloxacin was the most active agent in both potency and antibacterial spectrum against the test organisms. These results suggest the potential use of norfloxacin in the treatment of superficial bacterial infections of the eye.

Multicenter evaluation of the proposed quality control limits and interpretive zone standards for in vitro susceptibility testing with norfloxacin.

A seven-center collaborative study was carried out to evaluate the in vitro performance of the 10 micrograms norfloxacin disks on the basis of previously proposed interpretive susceptibility zone standards and quality control parameters. Of 7,858 clinical isolates tested, 93.2, 4.9, and 1.9% fell into the susceptible, moderately susceptible, and resistant groups, respectively. The quality control data based on a total of 1,368 zone diameter measurements compared quite favorably with the proposed performance limits as follows: Escherichia coli ATCC 25922, 28 to 35 mm versus 28 to 36 mm; Staphylococcus aureus ATCC 25923, 21 to 29 mm versus 17 to 29 mm; and Pseudomonas aeruginosa ATCC 27853, 23 to 27 mm versus 22 to 29 mm.

GELRITE as an Agar Substitute in Bacteriological Media.

GELRITE gellan gum (formerly known as PS-60 and S-60) is a new naturally derived, highly purified polysaccharide which displays several interesting properties, including selfgelling. The suitability of GELRITE as an agar substitute was tested by evaluating the performance of several media selected from among those most commonly used in the isolation, identification, and enumeration of microorganisms in clinical laboratories. Fifty different bacterial species previously implicated in human infections served as test strains. On the basis of the various parameters considered, namely, colony characteristics, biochemical reactions, hemolytic patterns, and plating efficiency, media gelled by agar and by GELRITE compared quite favorably.

Cefotaxime in the treatment of infections of the skin and skin structure.

In a series of open, noncomparative studies, cefotaxime was given to 360 hospitalized patients with bacterial wound infections such as cellulitis, abscesses, or necrotizing ulcers of the skin or subcutaneous tissues. The drug was administered intramuscularly or intravenously in a mean dosage of 4 g per day (range, 1.4-12.0 g per day) in three or four equal doses for at least five days. Clinical response to therapy could not be evaluated for 100 patients, and bacterologic response could not be evaluated for 145 patients. Clinical response was satisfactory in 93.5% of the 260 patients for whom therapy could be evaluated, and bacterial response was satisfactory in 84% of the 225 patients for whom therapy could be evaluated. These rates of response include both single- and multiple-pathogen infections. There were nine instances of superinfection.

In vitro comparison of N-formimidoyl thienamycin, piperacillin, cefotaxime, and cefoperazone.

The antibacterial activity of N-formimidoyl thienamycin was compared with those of cefotaxime, cefoperazone, and piperacillin against 536 clinical aerobic isolates.