Chlorocardicin, a monocyclic beta-lactam from a Streptomyces sp. II. Isolation, physico-chemical properties and structure determination

Chlorocardicin, a novel monocyclic beta-lactam, was isolated from the fermentation broth of a Streptomyces sp. by the use of non-ionic porous resin and reverse phase chromatography. This chlorine-containing antibiotic is structurally related to nocardicin A. Its physico-chemical characteristics and detailed NMR analysis are described.

Chlorocardicin, a monocyclic beta-lactam from a Streptomyces sp. I. Discovery, production and biological activities

Chlorocardicin is a new monocyclic beta-lactam produced by a Streptomyces sp. It is structurally related to nocardicin A but differs in having a m-chloro substituent on the p-hydroxyphenylglycine unit. The biological activity of chlorocardicin was similar to nocardicin A but the former showed less antagonism in complex media. Moderate in vitro activity was observed against Enterobacteriaceae and Pseudomonas aeruginosa. Chlorocardicin showed low activity against Staphylococcus aureus whereas nocardicin A was inactive. Both compounds were shown to be strongly potentiated by antibiotics that inhibit peptidoglycan biosynthesis and were antagonized by selected L- and D-amino acids.

[Classification of beta-lactams]

Redefinition of beta-lactams is needed as the many ongoing investigations produce an ever-increasing number of molecules. At the time being, there are four groups of beta-lactams: penams, cephems, penems, and monolactams.

A revised system for antibiotic sensitivity testing. The Swedish Reference Group for Antibiotics

A revised system for antibiotic sensitivity testing in Sweden was proposed in 1977. The new SIR system has been in sue in almost all Swedish routine bacteriological laboratories since 1979. The SIR system implied 2 main changes: 3 sensitivity groups instead of previous 4 and new breakpoints for the sensitivity groups. The new system is presented in comparison with 3 standardized systems currently in use (NCCLS, ICS and DIN systems).

Classification of polyene antibiotics according to their synergistic effect in combination with bleomycin A2 or fusidic acid

Five polyene antibiotics were compared for their effects on colony formation of either Chinese hamster V79 or Saccharomyces cerevisiae cells. A 10 to 40 times higher concentration of amphotericin B (heptaene) or nystatin (degenerated heptaene) was necessary to inhibit colony formation of hamster cells than that needed to inhibit colony formation of yeast cells. In contrast, colony formation of both hamster and yeast cells was inhibited to the same extent by similar concentrations of filipin (pentaene), pentamycin (pentaene), or pimaricin (tetraene). The five polyene antibiotics were also compared for their effects on colony formation of either V79 or S. cerevisiae cells when combined with a nonpolyene antibiotic, fusidic acid or bleomycin A2. Amphotericin B or nystatin could augment the cytocidal effect of fusidic acid but not that of bleomycin A2, whereas pentamycin or pimaricin could augment the cytocidal effect of both fusidic acid and bleomycin A2 against hamster and yeast cells. Filipin was found to enhance the action of fusidic acid and bleomycin upon growth of mammalian cells, whereas the pentaene polyene significantly potentiated the action of fusidic acid, but not that of bleomycin A2, against S. cerevisiae. It was therefore suggested that these polyene antibiotics be classified into two groups: group 1 (pimaricin, pentamycin, and filipin) and group 2 (amphotericin B and nystatin).

Gonorrhea in the male: some aspects of treatment in Lebanon

One hundred male patients with acute gonococcal urethritis were treated with various antibiotic and chemotherapeutic regimens. Pivampicillin, 1400 mg orally in two divided does at 5 hours' interval gave 100% cure in 60 patients. Gentamicin, 280 mg IM in one dose was equally efficaceous in 15 patients. Ampicillin and Trimethoprim-sulfamethoxazole gave cure rates of around 70%. While the results of the first two groups were in agreement with data published in different parts of the world, our results with the later two groups were contrary to those of other authors. The need for periodic evaluation of various antibiotic regimens in the treatment of gonorrhea is indicated.