Cefuroxime, a new cephalosporin antibiotic, was inhibitory at low concentrations to several types of gram-negative bacteria. It was considerably more stable than cephaloridine or cephalothin to the beta-lactamases produced by Escherichia coli (RP1), Klebsiella aerogenes K1 and Enterobacter cloacae P99. Concentrations of cefuroxime much greater than the minimum inhibitory concentration (MIC) were usually necessary to induce lysis of beta-lactamase and non-beta-lactamase producers. In contrast, cephaloridine, cephalothin and ampicillin were rapidly bacteriolytic at, or near, the respective MIC against non-beta-lactamase producers, whereas the activity of these three antibiotics was considerably reduced against beta-lactamase-producing strains.

Cephalosporins↗

PubMed1978

Pretreatment with colistin and Proteus sensitivity to other agents.

The effects of pretreatment with colistin (polymyxin E) on the sensitivity of Proteus mirabilis, P. vulgaris and P. morganii strains to tris and sodium deoxycholate (DOC) have been studied. Pretreatment of two P. mirabilis strains (NCTC 60 and 4199) with low concentrations (0.25 approximately 1 microgram/ml) of colistin rendered them sensitive to lysis by tris (0.05M) or DOC (250 approximately 1,000 microgram/ml) although DOC induced lysis of control (non-colistin-treated) suspensions also. In contrast, the other P. mirabilis strains, as well as the P. vulgaris and P. morganii strains were little affected by tris (0.2M) or DOC (10,000 microgram/ml) even after exposure of the cells to high colistin concentrations (up to 500 microgram/ml). Colistin-pretreated or control cells of P. mirabilis NCTC 60 rapidly lost viability when suspended in water but not when held in 0.16M sodium chloride solution. Ethylenediamine tetraacetate-pretreated cells of strains 60 and 4199 were fairly sensitive to tris, although the extent of the lysis was less than when colistin was used as pretreating agent. One strain of P. vulgaris (NCTC 4175) became sensitive to tris and to DOC following exposure of the cells to ampicillin.

Colistin↗

PubMed1977

The antibacterial activity of a new chloroxylenol preparation containing ethylenediamine tetraacetic acid.

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Chlorhexidine↗

PubMed1977

Surface properties of cells of some methicillin-resistant strains of Staphylococcus aureus.

Methicillin-sensitive (MS) cells of Staphylococcus aureus had a minimum electrophoretic mobility at pH 4.5, whereas methicillin-resistant (MR) strains showed only a slight plateau effect. Trypsin removed the trough effect of the MS Oxford strain. There was no correlation between surface lipid and resistance in MR strains. Cell walls of MS strains contained much more teichoic acid than walls of MR strains. Lysostaphin lysed all MR and MS strains, and mucopeptide does not appear to be involved in resistance to methicillin.

Cell Movement↗

PubMed1976