There are many examples of two penicillins acting synergistically, usually by one competitively inhibiting beta-lactamase, thus protecting the other from inactivation. There are few reports on penicillins antagonizing each other. Eight strains of three genera (Proteus, Escherichia, Pseudomonas) isolated at Boston City Hospital or Institut Pasteur, Paris, showed antagonism of carbenicillin or am...

A physicochemical method has been developed by which 5 to 75 y (8 to 120 Oxford units) of penicillin per ml. may be determined within an error of f5 per cent. The procedure requires about 20 minutes for one complete analysis, but a large number of samples may be analyzed at one time. Since crystalline penicillins G, X, K, and F have nearly the same extinction per unit weight, a single measureme...

Membranes of BaciZZus subtilis to which [14C]penicillin G had been bound were fractionated by polyacrylamide gel electrophoresis in the presence of sodium dodecyl sulfate. Five labeled components were separated. These five components differed from each other in the rates at which they bound penicillins and cephalosporins by up to four orders of magnitude. The major penicillin-binding component,...

Peptidoglycan transpeptidase and dd-carboxypeptidase have been detected in isolated membranes of Pseudomonas aeruginosa. Cephalosporins and penicillins fail to inhibit the transpeptidase at concentrations as high as 100 mug/ml. dd-Carboxypeptidase, on the other hand, is sensitive to inhibition by beta-lactam antibiotics. The presence of dimethyl sulfoxide in the reaction mixture results in a tw...

We compared antimicrobial susceptibility patterns of 206 group B streptococcal (GBS) strains isolated from pregnant women and six from neonates/infants with invasive infection during the two periods 1985-1986 and 1999-2000. All strains in both periods were susceptible to the penicillins, cephalosporins and carbapenem tested. Seven (3%) isolates were resistant to erythromycin and three (1%) were...

Cephaloridine ('Ceporin') is a semisynthetic compound, 7[(2-thienyl)-acetamide]-5(i-pyridylmethyl)-5-cephem-4-carboxylic acid betaine, derived from cephalosporin C. This is an antibiotic produced by Cephalosporium acremonium, a fungus isolated from a sewage outfall off the Sardinian coast (Brotzu, I948). The cephalosporins are closely related chemically to the penicillins in that they contain a...

Using 20 clinical isolates of S. aureus (all bacteriophage 80/81 type), we found that lysostaphin inhibits the growth of all cultures at concentrations significantly lower than those observed with any of eight penicillins, a penicillin-like compound (cephalothin), or fusidic acid (a steroid antibiotic). All test cultures were shown to be resistant to penicillin G, ampicillin, and propicillin. O...