Affiliation:
1. Service de Bactériologie-Virologie, Hôpital de Bicêtre, Assistance Publique/Hôpitaux de Paris, Faculté de Médecine Paris-Sud, Université Paris XI, 94275 Le Kremlin-Bicêtre
2. Centre d'Etudes Pharmaceutiques, Châtenay-Malabry, France
Abstract
ABSTRACT
Carbapenem-hydrolyzing oxacillinases are reported increasingly in
Acinetobacter baumannii
. Since they hydrolyze carbapenems at low levels, the roles of carbapenem-hydrolyzing oxacillinases OXA-23, OXA-40, and OXA-58 in
A. baumannii
were determined. The
bla
OXA-23
,
bla
OXA-40
, and
bla
OXA-58
genes were inserted in broad-host-range plasmid pAT801 and transformed in
Escherichia coli
DH10B and in
A. baumannii
CIP 70.10 and its point mutant derivative
A. baumannii
BM4547, which overexpresses the efflux pump AdeABC. Natural plasmids harboring the
bla
OXA-23
and
bla
OXA-58
genes were also transformed in
A. baumannii
CIP 70.10. In addition, the
bla
OXA-40
gene was inactivated at its chromosome location in
A. baumannii
CLA-1. Intermediate levels of resistance or reduced susceptibilities to carbapenems were observed for
A. baumannii
transformants expressing OXA-23, OXA-40, and OXA-58. The inactivation of
bla
OXA-40
in
A. baumannii
CLA-1 yielded reduced susceptibilities to carbapenems. Carbapenem-hydrolyzing oxacillinases OXA-23, OXA-40, and to a lesser extent OXA-58 play a role in carbapenem resistance in
A. baumannii
, and overexpression of efflux pump AdeABC may also contribute to higher levels of resistance to β-lactams, including carbapenems.
Publisher
American Society for Microbiology
Subject
Infectious Diseases,Pharmacology (medical),Pharmacology