[Dissemination of IMP-1 and OXA type beta-lactamase in carbapenem-resistant Acinetobacter baumannii].
BACKGROUND
Acinetobacter baumannii is an aerobic, gram-negative, glucose-nonfermenting bacterium, which has emerged as a serious opportunistic pathogen. In recent years, the increasing instance of carbapenem-resistant A. baumannii producing metallo-beta-lactamases (MBLs) or OXAtype beta-lactamases is causing a serious clinical problem. In this study, we investigated the prevalence of Ambler class A, B, and D beta-lactamases and their extended-spectrum derivatives in carbapenem-resistant A. baumannii isolates.


METHODS
A total of 31 consecutive, non-duplicate, carbapenem-resistant A. baumannii were isolated from three university hospitals in the Chungcheong province of Korea. The modified Hodge and inhibitor-potentiated disk diffusion tests were conducted for the screening of carbapenemase and MBL production, respectively. PCR and DNA sequencing were performed for the detection of beta-lactamase genes. We also employed the enterobacterial repetitive intergenic consensus (ERIC)-PCR method for the epidemiologic study.


RESULTS
Twenty-three of 31 isolates harbored bla(OXA-2)(51.6%), bla(OXA-23)(22.6%), bla(IMP-1)(48.4%),and bla(VIM-2)(3.2%). All of the OXA-2-producing strains also evidenced MBLs. The strains that harbored bla(OXA-23)were isolated only in hospital C, and only in a limited fashion. The ERIC-PCR pattern of the five OXA-23 strains indicated that the isolates were closely related in terms of clonality. The six strains producing IMP-1 isolated from hospital A were confirmed to be identical strains.


CONCLUSIONS
A. baumannii strains harboring IMP-1 or OXA-type beta-lactamases are currently widely distributed throughout the Chungcheong province of Korea. The most notable finding in this study was that a bla(OXA-2)-producing A. baumannii harboring MBL, which has not been previously reported, can also lead to outbreaks.
Sung
Ji Youn
JY
Department of Laboratory Medicine, Chungnam National University Hospital, Daejeon, Korea.
Kwon
Kye Chul
KC
Park
Jong Woo
JW
Kim
Yeon Suk
YS
Kim
Ji Myung
JM
Shin
Kyeong Seob
KS
Kim
Jong Wan
JW
Ko
Chi Seon
CS
Shin
So Youn
SY
Song
Jeong Hoon
JH
Koo
Sun Hoe
SH
D000151:Acinetobacter Infections / Q000382:microbiology; D040981:Acinetobacter baumannii / Q000187:drug effects / Q000201:enzymology* / Q000235:genetics; D000900:Anti-Bacterial Agents / Q000494:pharmacology*; D015780:Carbapenems / Q000494:pharmacology*; D052978:Disk Diffusion Antimicrobial Tests; D024901:Drug Resistance, Multiple, Bacterial; D006801:Humans; D016133:Polymerase Chain Reaction; D001618:beta-Lactamases / Q000096:biosynthesis / Q000235:genetics / Q000378:metabolism*
D000900:Anti-Bacterial Agents; D015780:Carbapenems; C409201:beta-lactamase IMP-1; C039404:beta-lactamase OXA-2; D001618:beta-Lactamases