Antimicrobial use and antimicrobial resistance in an intensive care burn department

The increasing consumption of antibiotics in hospitals and the economic implications of this increase led us to survey this consumption in the various hospital units. Our study proposes to measure the annual antibiotic use and antimicrobial resistance in an intensive care burn department in order to direct the control measures. During a 5-year period from 1 January 2000 to 31 December 2004 we studied the consumption of the following antibiotics: oxacillin, imipenem, ceftazidime, ofloxacin, ciprofloxacin, vacomycin. We measured antibiotic consumption with the antimicrobial density (AD), which takes into account the quantity of antibiotics in grams converted to the defined daily dose (DDD) and the number of days of hospitalization. The DDD was proposed by the World Health Organisation. The calculation of the AD for each molecule was carried out according to the following formula: AD = (quantity consumed [g] for the particular antimicrobial × 1000) / (DDD for that antimicrobial × number of days hospitalized).

The study of the total consumption of antibiotics showed a peak in 2002. The distribution by families of antibiotics shows variations according to various molecules. Among oxacillin, a significant decrease in the consumption of this molecule was observed in 2004 (AD = 44 in 2004 vs AD = 128.2 in 2002). At the same time, a significant increase in the consumption of vancomycin (AD = 28.15 in 2002 vs 73.9 into 2004) was also observed. This intensive use of vancomycin was explained by the high incidence of the methicillin-resistant Staphylococcus aureus in our burn department (MRSA = 64% in 2004). As elsewhere, no vancomycin intermediate S. aureus was detected during the period of study, in spite of the significant use of this antibiotic. There were statistically significant relationships between increasing use of ceftazidime and ceftazidime-resistant Klebsiella pneumoniae (r s = 0.93, P = 0.02). Concerning the fluoroquinolones, there were statistically significant relationships between increasing use of ciprofloxacin and incidence of resistant P. aeruginosa to this antibiotic (r s = 0.89, P = 0.043). In addition to the resistance to the drug itself, the consumption of ciprofloxacin was significantly associated with resistance to the imipeneme in P. aeruginosa (r s = 0.87 P = 0.05). A restriction of the use of ciprofloxacin was taken during 2003 and 2004; this was followed by a significant decrease of resistance in P. aeruginosa. The use of fluoroquinolones was not significantly associated with MRSA (r s = 0.70, P = 0.1).

The monitoring of both antibiotic consumption and antibiotic resistance makes it possible to set up targeted policies and to control their effectiveness. Nevertheless this monitoring must be integrated into a policy of good use and control of antibiotic use.