Association between antibiotic use and changes in susceptibility patterns of Pseudomonas aeruginosa in an intensive care burn unit: a 5-year study, 2000-2004.

This study aimed to evaluate the relationship between antimicrobial resistance in Pseudomonas aeruginosa and annual antibiotic use in a burn unit. From 1 January 2000 to 31 December 2004, 203 non-repetitive strains of Ps. aeruginosa were recovered from various clinical specimens. Antimicrobial susceptibility testing was performed using the disc diffusion method, and susceptibility data were interpreted according to break points recommended by the French Society of Microbiology. The antibiotic consumption for imipenem, ceftazidime, cefotaxime, piperacillin-tazobactam, ofloxacin, ciprofloxacin, gentamicin and amikacin was calculated with antimicrobial density. The relationship between antibiotic use and the resistance of Ps. aeruginosa was analysed. The consumption of ceftazidime and amikacin showed no association with resistance. A statistically significant relationship was observed between increasing use of ciprofloxacin and the incidence of resistant Ps. aeruginosa to this antibiotic (rs=0.89, p=0.05), and a significant correlation between ciprofloxacin consumption and resistance to imipenem was noted (rs=0.89, p=0.043). Restricted use of ciprofloxacin during 2003 and 2004 was followed by a significant decrease of resistance in Ps. aeruginosa. Our report illustrates the major role of ciprofloxacin in the emergence of resistant Ps. aeruginosa.