Abstract
The antimicrobial use density (AUD) of carbapenems, proportion of carbapenem-resistant Pseudomonas aeruginosa, and cross resistance rate were investigated in patients admitted to our hospital between 2005 and 2007. Furthermore, epidemiological factors associated with the detection of carbapenem-resistant P. aeruginosa were examined. The mean AUD of all carbapenems in 2005, 2006, and 2007 was 13.63±3.43, 17.06±2.31, and 17.97±4.37, respectively, showing a significant increase. In particular, the increase in the AUD of meropenem (MEPM) was marked. The proportion of MEPM-resistant P. aeruginosa significantly increased from 6.9% in 2005 to 12.0% in 2007. The proportions of MEPM-resistant P. aeruginosa in imipenem/cilastatin(IPM/CS)-resistant and panipenem/betamipron (PAPM/BP)-resistant strains were 50 and 44.2% in 2005, respectively, and rapidly increased to 79.5 and 65.3% in 2007, respectively, suggesting an association between the resistance rate and doses of antimicrobial agents. A case-control study analysis showed that the risk factors associated with the detection of carbapenem-resistant P. aeruginosa included the usage of carbapenems (odds ratio: 7.55, 95% confidence interval: 2.96-19.23, p<0.0001) and central catheter insertion (odds ratio: 2.89, 95% confidence interval: 1.19-7.02, p=0.019). The total dose was significantly higher in the resistant group than in the sensitive group (resistant group, 16.8±11.2 g; sensitive group, 10.2±5.25 g), and the total administration period was significantly longer in the resistant group than in the sensitive group (resistant group, 17.1±11.6 day; sensitive group, 9.96±4.85 day). The maximum administration period per prescription was significantly different between the two groups (resistant group, 11.5±5.3 day ; sensitive group, 9.25±3.74 day). The results of this study suggest that unnecessary antimicrobial therapy should be avoided to prevent the appearance of antibiotic-resistant bacteria. Therefore, limiting the administration period to within 10 days may be important.
