Relation between the antimicrobial susceptibility of clinical isolates of Pseudomonas aeruginosa from respiratory specimens and antimicrobial use density (AUD) from 2005 through 2008.
OBJECTIVE
To examine the relation between annual trends in the antimicrobial susceptibility of Pseudomonas aeruginosa and drug usage, we compared annual changes in the susceptibility rates of P. aeruginosa clinical isolates during a 4-year period and annual trends in the overall usage of antimicrobials during the same period.


METHODS
We studied annual trends in MIC(90)/MIC(50), antimicrobial use density (AUD), and antimicrobial susceptibility rates based on clinical breakpoints for 150 strains of P. aeruginosa isolated from respiratory specimens at Dokkyo Medical University Hospital from 2005 through 2008.


RESULTS
The MIC(90)/MIC(50) of antimicrobials effective against P. aeruginosa in years 2005, 2006, 2007, and 2008 were as follows: imipenem, 32/2, 32/1, 8/2, and 16/1 microg/mL; meropenem, 8/1, 8/1, 4/0.5, and 4/0.5 microg/mL; and biapenem, 16/1, 32/0.5, 4/0.5, and 8/0.5 microg/mL, indicating that susceptibility to carbapenems increased slightly. The MIC(90)/MIC(50) was 4/0.25, 2/0.125, 1/0.125, and 2/0.25 microg/mL for ciprofloxacin, 8/4, 8/4, 4/4, and 8/4 microg/mL for amikacin, 64/16, 64/16, 64/16, and 64/16 microg/mL for sulbactam/cefoperazone, 8/2, 16/2, 32/2, and 8/2 microg/mL for ceftazidime, indicating little change. The AUDs of fourth-generation cephalosporins increased from 2005 to 2008 (16.2, 18.4, 28.0, and 23.0), while the AUDs of carbapenems decreased (25.7, 23.7, 10.9, and 12.5).


CONCLUSIONS
The decrease in the AUDs of carbapenems was associated with increased susceptibility rates of P. aeruginosa to carbapenem derivatives. A continuous understanding of trends in the resistance of P. aeruginosa and various other pathogens is essential for designing countermeasures against nosocomial infections, including the proper and effective use of antimicrobials.
Fukushima
Yasutsugu
Y
Department of Pulmonary Medicine and Clinical Immunology, Dokkyo University School of Medicine, Japan. y-fuku@dokkyomed.ac.jp
Fukushima
Fumiya
F
Kamiya
Kuniyoshi
K
Hayashi
Yumeko
Y
Tatewaki
Masamitsu
M
Yamada
Issei
I
Hirata
Hirokuni
H
Sugiyama
Kumiya
K
Ishii
Yoshiki
Y
Fukuda
Takeshi
T
D000900:Anti-Bacterial Agents / Q000494:pharmacology* / Q000627:therapeutic use; D004352:Drug Resistance, Microbial; D024901:Drug Resistance, Multiple, Bacterial; D006785:Hospitals, University / Q000639:trends; D006801:Humans; D008826:Microbial Sensitivity Tests / Q000639:trends; D011552:Pseudomonas Infections / Q000188:drug therapy / Q000382:microbiology; D011550:Pseudomonas aeruginosa / Q000187:drug effects / Q000302:isolation & purification*
D000900:Anti-Bacterial Agents