Analysis of antibiotic consumption and microorganism resistance changes

Objective. The main goal of this study was to evaluate the variation of antibiotic consumption and relation between antibiotic consumption and microorganism resistance.
Material and methods. This analysis was performed in one of Lithuanian tertiary hospitals. The defined daily dose (DDD) analysis was performed to express drug consumption per every 100 occupied bed days (OBDs) for single units in clinical departments. Average of DDD/100 OBDs was estimated for 2004–2007, and mean values were compared among all four years. The relation between the number of surgical operations and antibiotic consumption in surgery departments was analysed. E. coli and K. pneumoniae resistance for four years (2004–2007) was determined. Moreover, the relation between microorganism resistance and variation of antibiotic consumption was determined. Data were analysed by descriptive and comparative statistics (by Mann–Whitney test for nonparametric criteria and Spearman correlation).
Results. Comparing the DDD/100 OBD data during 2004–2007 revealed a statistically significant increase in piperacillin and tazobactam (877.50%), metronidazole (114.00%), cefuroxime (77.31%), meropenem (47.55%), cefoperazone and sulbactam (173.11%) consumption. The increased usage of these antibiotics was determined in surgery department too. However, the increased number of surgical operations cannot be the only reason of the growing antibiotic consumption. Results revealed a statistically significant decrease in ofloxacin use from 2006 to 2007 (93.94%). E. coli resistance to ampicillin (from 49.80% to 56.60%), ampicillin and sulbactam (from 25.50% to 39.20%), cefuroxime (from 7.40% to 10.10%), ciprofloxacin (from 4.20% to 12.50%), gentamicin (from 11.40% to 13.20%) and K. pneumoniae resistance to ampicillin and sulbactam (from 45.40% to 56.40%), cefuroxime (from 34.00% to 39.10%), ciprofloxacin (from 5.50% to 10.50%), gentamicin (from 32.00% to 35.80%) increased. A statistically significant positive correlation between quinolone consumption and K. pneumoniae resistance to ciprofloxacin was determined (r=1, P<0.05).
Conclusions. In 2004–2007, the usage of piperacillin and tazobactam, metronidazole, cefuroxime, meropenem, cefoperazone, and sulbactam increased. In 2006–2007, ofloxacin consumption decreased. The changes in other antibiotic usage were statistically insignificant. In 2004–2007, E. coli and K. pneumoniae resistance to ampicillin and sulbactam, cefuroxime, ciprofloxacin, gentamicin and E. coli resistance to ampicillin increased. A statistically significant positive correlation between quinolone consumption and K. pneumoniae resistance to ciprofloxacin was determined.