Enterobacter, Citrobacter 및 Serratia 균종의 최근 5년간 분리추세와 변이성 AmpC β-lactamase 생성 균주의 항균제에 대한 감수성

Abstract

Background: Derepressed Ampc β-lactamase producing Enterobacter cloacae, Citrobacter freundii, and Serratia marcescens are important nosocomial pathogens and the infection s are difficult to treat, because they are multi-drug resistant. The aim of this study was to determine the isolation rate and trend, and antimicrobial susceptilibity of derepressed strains isolated from clinical specimens.

Methods: E. cloacae, S. marcescens, and C. freundii isolated from 1996 through 200 were enrolled in the study. Antimicrobial susceptibility was tested by NCCLS disk diffusion method. Derepressed strain was defined as strain non-susceptilble to third generation cephalosporin. The isolation patterns of important gram-negative bacilli with the derepressed strains were analyzed with respect tot years, patient's locations and specimens.

Results: Among the clinical isolates, the derepressed strains of E. cloacae, s. marcescens, and C. freundii were 65%, 70%, and 56%. The proportion of the derepressed strains : E. cloacae increased from 68% in 1996 to 71% in 1998, however, decreased to 59% in 2000. S. marcescens increased from 68% in 1996 to 73% in 2000, C. freundii decreased from 69% in 1996 to 41% in 2000. The proportion of the derepressed strains were high among the isolates from blood and respiratory specimens of inpatient and intensive care patient. The resistance rates of the depressed strains were 47∼62% to third generation cephalosporin and aztreonam, 15∼85% to aminoglycoside, 68% to cotrimoxazole, and 31% to levofloxacin.

Conclusion: Among the clinical isolates of E. cloacae, S. marcescens, and C. freundii, the derepressed strains were as high as 56∼70%, and they were commonly isolated from blood and sputum specimens of inpatient and intensive care patient, and showed high resistane rates to the most antimiccrobiall agents.