In vitro antibacterial activity of norfloxacin (MK-0366)

The in vitro activity of norfloxacin (MK-0366) compared with that of beta-lactam antibiotics and, where appropriate of gentamicin or metronidazole was assessed against recent clinical isolates of common bacteria. The compound was highly active against most enterobacteria (minimal inhibitory concentrations [MICs], 0.008 to 32 micrograms/ml; 90% inhibited by 0.25 micrograms/ml), Haemophilus influenzae (MICs, 0.03 to 0.12 micrograms/ml), and Neisseria gonorrhoeae (MICs, 0.008 to 0.016 micrograms/ml). It was also active against Pseudomonas aeruginosa (MICs, 0.12 to 2 micrograms/ml), most other pseudomonads (MICs, 0.03 to 32 micrograms/ml), and Acinetobacter calcoaceticus (MICs 0.06 to 4 micrograms/ml). Norfloxacin was somewhat less active against staphylococci (MICs, 0.25 to 4 micrograms/ml; 1 microgram/ml required to inhibit 50% of isolates) and streptococci (MICs, 0.5 to 64 micrograms/ml). Members of the Bacteroides fragilis group of anaerobes were relatively resistant to norfloxacin (MICs, 8 to 128 micrograms/ml), as were most other anaerobes.

In vitro antibacterial activity and susceptibility of the cephalosporin Ro 13-9904 to beta-lactamases

The in vitro activity of Ro 13-9904 was assessed against clinical isolated of common bacteria. Its activity against most enterobacteria was similar to that of cefotaxime and moxalactam, but it was even more active than these compounds against all Proteus species. It was also highly active against Haemophilus influenzae and Neisseria gonorrhoeae, including beta-lactamase producers. Like cefotaxime and moxalactam, Or 13-9904 was approximately eightfold more active than carbenicillin against most isolates of Pseudomonas aeruginosa and also active against highly carbenicillin-resistant isolates, but it was relatively inactive against moderately carbenicillin-resistant isolates. Ro 13-9904 also resembled cefotaxime and moxalactam in that it was active, though less so than cephaloridine, against staphylococci and streptococci, except for methicillin-resistant staphylococci and Streptococcus faecalis, which were resistant to it. It was less active than cefoxitin but slightly more active than ampicillin against both Bacteroides fragilis and other Bacteroides spp. Ro 13-9904 was resistant to most beta-lactamases but was attacked by enzymes from B. fragilis, isolates of indole-positive Proteus species, and also by a cefoxitin-hydrolyzing enzyme from an isolate of Enterobacter cloacae.

In vitro antibacterial activity and susceptibility of cefsulodin, an antipseudomonal cephalosporin, to beta-lactamases

Cefsulodin sodium (SCE-129, CGP-7174/E), active in minimum inhibitory concentrations (MICs) of 0.5 to 64 microgram/ml, was about 16- to 32-fold more active than carbenicillin against Psuedomonas aeruginosa. It was also active against P. diminuta, P. maltophilia, P. paucimobilis, and P. pseudoalcaligenes (MICs of 1 to 32 microgram/ml) but not against other species of Pseudomonas or other gram-negative bacteria. Except with highly carbenicillin-resistant isolates, MICs of cefsulodin for P. aeruginosa were little affected by an increase in the inoculum. With a small inoculum, minimum bactericidal concentrations (MBCs) were the same as or twice the MIC, but increasing the inoculum had a greater effect on the MBC than on the MIC. Cefsulodin was not hydrolyzed by the beta-lactamase induced in P. aeruginosa by growth in the presence of benzylpenicillin and was a poor substrate for beta-lactamases from Enterobacter cloacae and Proteus morganii. However, it was hydrolyzed, albeit slowly, by the beta-lactamase produced by most of our highly carbenicillin-resistant isolates of P. aeruginosa and by TEM-type beta-lactamases.

A taxonomic study of clinical isolates of Pseudomonas pickettii, 'P. thomasii' and 'group IVd' bacteria

On the basis of cluster analysis, average similarities within and between groups, and DNA base composition of selected strains, Pseudomonas pickettii appeared to be a distinct species comprising several biotypes. Although some or all of these biotypes, represented by subclusters in our computer study, may ultimately warrant recognition as separate species, our results were not conclusive enough to warrant such a proposal at present. Most strains tentatively named 'P. thomasii' could be included in P. pickettii so that the name P. pickettii, which was validly published whilst 'P. thomasii' was not, takes priority over 'P. thomasii'. Strains of Group Va (Tatum et al., 1974) examined were also included in P. pickettii. Group IVd (King, 1964) did not appear to be a natural group but some of the strains could also be included in P. pickettii.

Effect of dextran on cerebral function and blood after cardiac arrest. An experimental study on the dog

EEG activity and regional cerebral blood flow were monitored during 5 hour survival following cardiac arrest in 32 pentobarbital anesthetized mongrel dogs. The animals were mechanically ventilated and blood gases were maintained at physiologic levels. Regional cerebral blood flow and cardiac output were measured using 15 mu microspheres. EEG was recorded from 6 epidural electrodes using bipolar techniques. The animals were divided into 3 groups. The animals in Group I had an arrest of 8-11 minutes and those in Group II and III had an arrest of 12-16 minutes. Group II animals received no treatment. Group III animals were given 1 g/kg of dextran 40 at a concentration of 10% in normal saline following the arrest and maintained with 10 mg/kg/min during the 5 hours of recovery. In Groups I and III there was shorter duration of a flat EEG and 5 hours after the arrest the EEG activity was closer to normal than in Group II. After 5 hours the EEG scores of Group III were significantly greater than Group II (p less than 0.03). The cortical grey matter and hippocampus had the greatest reduction of blood flow following cardiac arrest. The mean cortical grey matter blood flow in Group II was less than in Groups I and III at 3 hours. After 5 hours the grey matter blood flow was greater in Group III than in Group II (p less than 0.09). The findings of this study are consistent with the hypothesis that after cardiac arrest perfusion abnormalities persist or develop after return of blood pressure and that these can be corrected or prevented with improved functional survival by treatment with dextran 40 after the arrest.

Platelet and plasma beta thromboglobulin in myeloproliferative syndromes and secondary thrombocytosis

Elevated plasma beta thromboglobulin (betatg) and decreased intracellular platelet betatg were found in patients with various myeloproliferative disorders. In secondary thrombocytosis, similar, but less marked changes were found. The abnormalities were increased during episodes of clinical thrombosis and could be suppressed in two-thirds of cases by aspirin therapy.

The identification of pseudomonads and related bacteria in a clinical laboratory

Non-fermenting, catalase-positive Gram-negative bacilli that grow on nutrient agar are often isolated in clinical laboratories. We have applied biochemical techniques appropriate to a typical clinical microbiology laboratory, and for the most part described in Cowan and Steel's Manual for the identification of medical bacteria (Cowan, 1974), to 428 clinical isolates and have evolved a scheme for their identification. Organisms were subdivided into groups on the basis of three tests, namely the glucose oxidation-fermentation test and tests for oxidase activity and motility. A choice was then made among other tests to produce indentification tables, containing only the most useful tests, for the various groups. The most complicated table has only 16 tests. This simple system identified 96.5% of the 428 organisms, as well as many subsequent isolates of the more common organisms.

API ZYM: a simple rapid system for the detection of bacterial enzymes

The API ZYM system of detection of enzymes has been applied to 81 bacteria belonging to several species. It was found to be easy to use and has produced results that may be useful in the identification of a variety of bacteria.

Antibacterial activity of cefuroxime, a new cephalosporin antibiotic, compared with that of cephaloridine, cephalothin, and cefamandole

The in vitro activity of cefuroxime, a new cephalosporin derivative, was compared with that of cephaloridine, cephalothin, and cefamandole against strains of gram-positive and gram-negative bacteria recently isolated from clinical sources. Cefuroxime showed very similar activity to cefamandole against Staphylococcus aureus, Haemophilus influenzae, and most members of the Enterobacteriaceae. It was more active than cefamandole against gonococci, pneumococci, and most streptococci. Increasing the inoculum size appeared to have less effect on the minimum inhibitory concentrations of cefuroxime for gram-negative bacilli than has been found with the other cephalosporin derivatives, and minimum bactericidal concentrations of cefuroxime were only marginally greater than minimum inhibitory concentrations.