Sporeamicin A, a new macrolide antibiotic. III. Biological properties.

Sporeamicin A is a new erythromycin-type antibiotic isolated from a species of Saccharopolyspora. It was active in vitro against a wide variety of Gram-positive bacteria. In vitro studies indicated that the sporeamicin A was stable in the presence of human serum, although it was bound to serum proteins. Sporeamicin A was effective in the mouse protection test against Staphylococcus aureus, Streptococcus pyogenes and Streptococcus pneumoniae. Sporeamicin A attained higher plasma and tissue levels in the rat than did erythromycin stearate.

[Effects of macrolide antibiotics against mucoid Pseudomonas aeruginosa].

Macrolide antibiotics at concentrations by far lower than their MICs proved to inhibit the production of alginate, elastase, and protease by mucoid Pseudomonas aeruginosa. The morphological study of mucoid P. aeruginosa under the electron microscope revealed the slime-like structures common to the cell morphology of the organism in cultured colonies and foci in a model for respiratory tract infection in mice, and the strains of mucoid P. aeruginosa which had been allowed to get in contact with the drugs proved to produced obviously fewer slime-like structures than control strains. The effect of a 14-membered macrolide, erythromycin, against mucoid P. aeruginosa was also observed with a 16-membered macrolide, rokitamycin this effect appeared to be common to the macrolide.

[Synergistic activity of isepamicin and beta-lactam antibiotics against Pseudomonas aeruginosa in vitro and in vivo].

Synergistic activities of isepamicin (ISP) and a beta-lactam antibiotic such as piperacillin (PIPC) or cefotaxime (CTX) against Pseudomonas aeruginosa were demonstrated in vitro and in vivo. In vitro synergistic activity was observed when ISP was used together PIPC or CTX. The synergy observed in vitro was reproduced in vivo against experimental mouse infections, and a ISP-PIPC or a ISP-CTX combination showed significantly greater protective effects than individual antibiotics by themselves.

The acetylation of 6'-amino group of amikacin by a new enzyme prepared from serratia sp.

It was found that Serratia marcescens 43, Serratia proteamaculans 48 and Serratia sp. 45, all of which were clinically isolated, produced a new type of aminoglycoside acetyltransferase which acetylated amikacin at the 6'-amino group. 1-N-[(S)-3-Amino-2-hydroxypropionyl]-gentamicin B (HAPA-B, SCH 21420) and gentamicin C2 were hardly inactivated by the enzymes and had effective antimicrobial activities against these strains both in vitro and in vivo. This kind of aminoglycoside acetyltransferase should be classified into a new group other than previously reported AAC(6') enzymes.

[Latent infection with Corynebacterium kutscheri in mice after peroral inoculation and its provocation by cortisone (author's transl)].

Latent infection with Corynebacterium kutscheri in mice and its provocation by cortisone were studied with a rifampicin-resistant strain of the organism. Mice having been infected perorally began to excrete the organisms in feces within 6 hours, and most of them were found to be carrying the organisms in the intestine, especially in the cecum even 90 days after infection. In such state of latency, however, no organisms were detected in other main organs, and neither visible lesions nor serum agglutinin was detectable. The latent infection with excretion of the organisms in feces after peroral infection was shown to become overt and fatal by cortisone treatment made even 90 days after infection. In infected mice excreting no organisms in feces and having bites on their skin, the wounds became severe ulcers after cortisone treatment resulting in septicemia.