Glucoprotamin antimicrobial activity against selected standard antibiotic-resistant bacteria and reference strains used in the assessment of disinfection efficacy.

Background: The ability of bacteria to develop common mechanisms of resistance to antibiotics and disinfectants raises doubts about the effectiveness of disinfection processes. Glucoprotamin (GP) is an antimicrobial active substance which is widely used to the disinfection in medical area.

Objective: The aim of study was to compare GP's effectiveness with susceptibility of reference strains used for the evaluation of bactericidal efficacy of disinfectants Staphylococcus aureus (S. aureus); Pseudomonas aeruginosa (P. aeruginosa) and standard antibiotic-resistant strains: meticillin-resistant S. aureus (MRSA) and tetracycline-resistant P. aeruginosa (PAO-LAC).

Material And Methods: Minimum inhibitory concentrations (MICs) of GP and minimum bactericidal concentrations (MBCs) against tested strains were evaluated by serial broth dilution technique. GP's efficiency was examined according to qualitative (phenol coefficient GP-PC) and quantitative (EN 1040: 2006) test methods.

Results: Gram-negative strains were more tolerant to GP than Gram-positive strains among tested strains. MRSA and S. aureus exhibited similar susceptibility to GP. PAO-LAC had significantly lower susceptibility to GP than P. aeruginosa (P≤0,05). There were no differences in GP efficiency against these strains based on GP-PC. According to PN-EN 1040: 2006 standard average obligatory reduction≥5 log10 was demonstrated in the active concentration of GP (84 mg/l) at obligatory 5 min contact time for PAO-LAC and P. aeruginosa. The differences in basis bactericidal activity between PAO-LAC and P. aeruginosa were obtained in the active concentration at 10 and 15 min contact time (P≤0,05).

Conclusions: Variation in a susceptibility of reference strains and antibiotic-resistant standard strains has no meaning at used clinically GP concentrations, which are higher than concentration causing basis bactericidal activity of GP.