Ciprofloxacin or imipenem use correlates with resistance in Pseudomonas aeruginosa.

OBJECTIVE

To investigate the relationship between ciprofloxacin or imipenem use and antimicrobial resistance in Pseudomonas aeruginosa.

METHODS

A retrospective review of monthly antimicrobial susceptibility reports for ciprofloxacin (1988 to 1995) and imipenem (1987 to 1995) against P aeruginosa and hospital antimicrobial use records at a tertiary care teaching hospital in Winnipeg, Manitoba. Data were entered into a relational database, R:Base 4.5++, collated, transferred to a spreadsheet and subjected to linear regression analysis. The relationship between ciprofloxacin or imipenem use and resistance was assessed using a Pearson correlation.

RESULTS

Ciprofloxacin-resistant P aeruginosa increased from 1.0% of all isolates in 1988 to 10.0% in 1995. A significant (P=0.05) correlation was demonstrated between the amount of ciprofloxacin use and prevalence of ciprofloxacin-resistant P aeruginosa (r=0.73, P=0.05). Imipenem-resistant P aeruginosa increased from 1.0% of isolates in 1987 to a maximum of 10.4% in 1991, and subsequently decreased to 5.4% in 1995. Imipenem use and the prevalence of imipenem-resistant P aeruginosa were significantly correlated (r=0.85, P=0.014).

CONCLUSIONS

Ciprofloxacin use was directly associated with ciprofloxacin resistance, and imipenem use was directly associated with imipenem resistance in P aeruginosa.