Phosphorylated inactivation of aminoglycosidic antibiotics by Pseudomonas aeruginosa

In vitro and in vivo antimicrobial activities of sporaricin A, a new aminoglycoside

The in vitro and in vivo antimicrobial activity of sporaricin A, a new aminoglycoside, was compared with that of amikacin, dibekacin, and gentamicin. Sporaricin A showed a broad spectrum of activity against various gram-positive and -negative bacteria, including amikacin-, dibekacin-, or gentamicin-resistant strains. Sporaricin A inhibited more than 90% of clinical isolates of staphylococci, Klebsiella, Enterobacter, Citrobacter, Serratia, and Proteus, except for P. morganii and P. inconstans, at the concentration of 3.13 microgram/ml. This activity, except for that against Serratia, was similar to that of amikacin. Against P. inconstans and S. marcescens, sporaricin A was more effective than amikacin, dibekacin, and gentamicin. However, its activity against Pseudomonas aeruginosa was relatively weak in comparison with three other aminoglycosides. Sporaricin A was highly effective against bacteria that had various aminoglycoside-inactivating enzymes and that were resistant to the other drugs tested, but it was not active against those with aminoglycoside 3-acetyltransferase-I. The activity of sporaricin A tended to be greater with a reduction in inoculum size of bacteria and an increase in medium pH and decreased slightly in the presence of 10 to 50% horse serum. The in vitro activity was confirmed by in vivo tests in experimental infections with various bacteria. Its protective effect seemed to be equal to or greater than that of amikacin or dibekacin.

Lividomycin resistance in staphylococci by enzymatic phosphorylation

Enzymatic inactivation of lividomycin (LV) was attempted with nine clinical isolates of staphylococci including LV-susceptible and -resistant strains. LV inactivation and the incorporation into LV of (32)P from gamma-(32)P-adenosine triphosphate were demonstrated in the presence of cell-free extracts from LV-resistant strains but not from LV-susceptible ones. The enzyme was purified approximately 82-fold from a resistant Staphylococcus aureus strain by means of ammonium sulfate fractionation and column chromatography. Some properties of the partially purified LV-phosphorylating enzyme were quite similar to those of an enzyme from Escherichia coli carrying an R factor conferring LV resistance, and the phosphorylated product of the drug was also found to be identical with that produced by E. coli carrying an R factor, i.e., 5''-phosphoryl-LV.

Phosphorylation of lividomycin by Escherichia coli carrying an R factor

A lividomycin-phosphorylating enzyme from a lividomycin-resistant strain of Escherichia coli carrying an R factor was partially purified by fractionation with ammonium sulfate and Sephadex G-100 column chromatography. The enzyme inactivated, in the presence of adenosine triphosphate and Mg(2+), several antibiotics having a d-ribose moiety linked to 2-deoxystreptamine, i.e., lividomycin A and B, neomycin, paromomycin, and vistamycin, but did not inactivate the kanamycins, streptomycin, or the gentamicin C components. Chemical studies of the inactivated product suggested that the phosphorylated site of the inactivated lividomycin was the hydroxyl group of the d-ribose moiety.

Antibacterial activity of lividomycin toward R factor-resistant strains of Escherichia coli

Forty-eight R factors conferring resistance to both kanamycin (KM) and streptomycin (SM) were demonstrated from 1,270 Escherichia coli strains of clinical origin. Among these R factors isolated, 42 also conferred resistance to the new antibiotic lividomycin (LV). Extracts of E. coli ML1410 carrying one such factor (R(M81)) inactivated LV as well as KM and SM. But extracts of E. coli ML1410 carrying an R factor (R(M82) or R(M83)) sensitive to LV could not inactivate LV. LV inactivation required both adenosinetriphosphate (ATP) and Mg(2+). Inactivated LV was reactivable by alkaline phosphatase. Isotopic studies with labeled ATP and elemental analysis of the reaction product indicate that it is a monophosphorylated derivative of LV.

Activity of lividomycin against Pseudomonas aeruginosa: its inactivation by phosphorylation induced by resistant strains

The antibacterial activity and enzymatic inactivation of lividomycin, a new aminoglycosidic antibiotic, were studied with 13 strains of Pseudomonas aeruginosa. The minimal inhibitory concentration of lividomycin was 12.5 to 25 mug/ml, and three strains were resistant to high concentrations of lividomycin (more than 200 mug/ml). It was found that P. aeruginosa TI-13 and K-11, highly lividomycin-resistant strains of clinical origin, strongly inactivated the drug. The third resistant strain, Km-41/R, was developed in vitro. Unlike the other resistant strains, Km-41/R, was developed in vitro. Unlike the other resistant strains, Km-41/R did not inactivate the drug, indicating that different mechanisms were involved in lividomycin resistance. By use of a cell-free extract from P. aeruginosa TI-13, the inactivation of lividomycin was found to be caused by the formation of a monophosphorylated product of the drug.