The influence of postantibiotic effects and postantibiotic effects of sub-inhibitory concentrations of quinolones and aminoglycosides on phospholipase C of Pseudomonas aeruginosa.

We have studied the postantibiotic effect (PAE) and postantibiotic sub-MICs effect (PA SME) of ciprofloxacin, pefloxacin, netilmicin and tobramycin on the production of phospholipase C (PLC) in a Pseudomonas aeruginosa strain isolated from clinical material. All antibiotics tested (postantibiotic phase evoked by 2.MIC) reduced the production of PLC, particularly pefloxacin to 13.

Inhibition of Pseudomonas aeruginosa alginate expression by subinhibitory concentrations of antibiotics.

The effects of subinhibitory concentrations (1/4, 1/8, 1/16 of the MIC) of quinolones (ciprofloxacin, enoxacin, nalidixic acid, norfloxacin, ofloxacin, pefloxacin), aminoglycosides (amikacin, gentamicin, netilmicin, streptomycin, tobramycin), beta-lactams (aztreonam, ceftazidime, imipenem, ticarcilin) and macrolides (erythromycin, roxitromycin) on the excretion of alginate by a P. aeruginosa strain were studied. Both beta-lactam and macrolide antibiotics were found ineffective at the concentrations tested, except erythromycin and imipenem at 1/4 MIC.

[The effect of subinhibitory concentrations of quinolone and macrolide antibiotics on production of thermolabile hemolysins in Pseudomonas aeruginosa].

The authors investigated the effect of subinhibitory concentrations (sub-MICs) of selected quinolones (enoxacine, nalidixic acid, norfloxacine) and macrolid antibiotics (erythromycin, roxitromycin) on the production of thermolabile haemolysin (phospholipase C) of P. aeruginosa. The activity of phospholipase C was markedly reduced by norfloxacine (more than 80%) and enoxacine (75 - 80%) in all sub-MICs.

Antimicrobial efficacy of quaternary bisammonium salts and the effect of their sub-MICs on Pseudomonas aeruginosa virulence factors.

Antipseudomonadal activity of homologous series of six quaternary bisammonium salts (QBAS) (4,7-dioxo-3,8-dioxadekan-1,1-[bis(alkyldimethyldiammonium dibromide)] as well as the effect of their subinhibitory concentrations (sub-MICs) on Pseudomonas aeruginosa virulence factors was studied. Antibacterial activity of QBAS increased up to a certain length of the chain and then decreased with further elongation. All the tested sub-MICs of QBAS caused a significant suppression of phospholipase C activity (to 0-41%).

Effect of quaternary ammonium salts and amine oxides on Pseudomonas aeruginosa.

Two quaternary ammonium salts, viz (1-methyldodecyl) trimethylammonium bromide (ATDBr) and tetramethylammonium bromide (TMABr), as well as two amine oxides, (1-methyldodecyl)dimethylamine oxide (ATDNO) and trimethylamine oxide (TMANO), were tested for their inhibitory activity on a Pseudomonas aeruginosa strain isolated from nosocomial infections. Only those compounds with long alkyl chains in their molecules (ATDBr and ATDNO) showed antimicrobial efficacy. In subinhibitory concentrations both compounds inhibited incorporation of [14C]-adenine and [14C]-leucine as precursors of macromolecular biosynthesis.