Gene cassette arrays, antibiotic susceptibilities, and clinical characteristics of Acinetobacter baumannii bacteremic strains harboring class 1 integrons.
OBJECTIVE
Acinetobacter baumannii isolates containing class 1 integrons belong to different clones, but only a few strains are successful at causing infection. This study was conducted to compare the characteristics among these clones with different epidemicity.


METHODS
Eighty eight bacteremic isolates of A. baumannii were collected in a medical center in Taiwan during a 3-year period. The gene cassettes and antibiotic susceptibilities of the bacterial isolates were delineated and the patients' characteristics were compared.


RESULTS
Class 1 integrons were detected in 75 isolates (85.2%). Most of the isolates belonged to 2 major clones, but only 1 of the 2 clones caused outbreaks in several hospitals in Taiwan. Restriction analyses of variable regions of the integron revealed identical gene cassettes among isolates within the same clone. The cassette arrays of the 3 clones were aacA4, catB8, aadA1 (clone I, epidemic clone); dhfr XII, unknown open reading frame (orfF), aadA2 (clone II, endemic clone); and aacC1, 2 unknown open reading frames (orfX, orfX'), aadA1a (clone III). The epidemic and endemic strains were multidrug resistant, but the former presented a higher resistance rate to ampicillin-sulbactam. Infections with epidemic strains were significantly associated with prior use of cephalosporins, but didn't contribute to a higher mortality rate.


CONCLUSIONS
Judicious use of cephalosporins and rapid identification using the integron typing method might be helpful for the prevention of further spread of strains with epidemic potential.
Lee
Yi-Tzu
YT
Department of Medicine, Chutung Veterans Hospital, Chutung, Taiwan.
Huang
Li-Yueh
LY
Chen
Te-Li
TL
Siu
Leung-Kei
LK
Fung
Chang-Phone
CP
Cho
Wen-Long
WL
Yu
Kwok-Woon
KW
Liu
Chen-Yi
CY
D000151:Acinetobacter Infections / Q000453:epidemiology / Q000382:microbiology*; D040981:Acinetobacter baumannii / Q000187:drug effects* / Q000235:genetics*; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D016470:Bacteremia / Q000453:epidemiology / Q000382:microbiology*; D003428:Cross Infection / Q000453:epidemiology / Q000382:microbiology*; D024881:Drug Resistance, Bacterial; D005260:Female; D006801:Humans; D032023:Integrons / Q000235:genetics; D008297:Male; D008826:Microbial Sensitivity Tests; D008875:Middle Aged; D015999:Multivariate Analysis; D021521:Ribotyping; D012307:Risk Factors; D018709:Statistics, Nonparametric