Inactivation of dihydrostreptomycin by Pseudomonas aeruginosa

The many antibiotic resistance and tolerance strategies of Pseudomonas aeruginosa

Pseudomonas aeruginosa is a bacterial pathogen associated with a wide range of infections and utilizes several strategies to establish and maintain infection including biofilm production, multidrug resistance, and antibiotic tolerance. Multidrug resistance in P. aeruginosa, as well as in all other bacterial pathogens, is a growing concern. Aminoglycoside resistance, in particular, is a major concern in P. aeruginosa infections and must be better understood in order to maintain effective clinical treatment. In this review, the various antibiotic resistance and tolerance mechanisms of Pseudomonas are explored including: classic mutation driven resistance, adaptive resistance, persister cells, small colony variants, phoenix colonies, and biofilms. It is important to further characterize each of these phenotypes and continue to evaluate antibiotic surviving isolates for novel driving mechanisms, so that we are better prepared to combat the rising number of recurrent and recalcitrant infections.

Antiviral activity of alpha-methyl-1-adamantanemethylamine hydrochloride

Three types of Staphylococcus aureus strains were isolated with respect to streptomycin (SM) and spectinomycin (SPC) resistance, namely, SM r SPC r , SM r SPC s , and SM s SPC r (r, resistant; s, sensitive). Curing experiments and transduction analysis of strain MS7990 (SM r .SPC r .EM r ) (EM, erythromycin) disclosed that the loci governing SM and SPC resistance are different and exist on different nontransferable plasmids ( r factor), one plasmid carrying the genes governing SM resistance and another possessing the genes governing resistance to both SPC and EM. Strain MS7990 (SM r .SPC r ) inactivated both drugs by adenylylation. Similarly, the SM r SPC s and SM s SPC r strains inactivated SM and SPC, respectively, by adenylylation, although the adenylylated positions of both drugs have not been established as yet. The adenylylated SM in staphylococci was shown to be different from 3″-adenylyl-SM, indicating the possibility of the existence of a different enzyme from SM3″-adenylyl transferase demonstrated in Escherichia coli strains.

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.

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.