Antibiotic resistance as an indicator of bacterial chlorhexidine susceptibility

The antibiotic and chlorhexidine (CHX) susceptibility of 70 distinct clinical isolates: Escherichia coli, Klebsiella pneumoniae, Pseudomonas aeruginosa, Acinetobacter baumannii, Staphylococcus aureus (not MRSA), Streptococcus pyogenes and Enterococcus faecalis (10 of each) were tested using minimal bactericidal (MBC) and/or minimal inhibitory (MIC) concentrations. Non-fermentative bacteria tolerated CHX at high concentrations; Gram-positive cocci, especially S. pyogenes, were the most susceptible. We found a good correlation between CHX and antibiotic susceptibility in both MIC and MBC among Gram-negative bacteria, and mainly in MBC among Gram-positive bacteria. Resistance to ciprofloxacin, imipenem, cefotaxime, ceftazidime, gentamicin and aztreonam appeared to indicate increased CHX resistance among Gram-negative bacteria. This finding gives clinicians the ability to predict CHX susceptibility according to routine antibiotic resistance testing.