[Resistance to imipenem in Enterobacter aerogenes].
BACKGROUND
In June, 1993, an Enterobacter aerogenes strain was isolated in the Hospital de la Creu Roja from Hospitalet de Llobregat (Barcelona), which was resistant against all beta-lactams, including imipenem. Since is unusual in Enterobacter sp. to isolate imipenem resistant strains, we decided to study its resistance mechanism.


METHODS
To study the E. aerogenes 174004/H resistance mechanism beta-lactamase isoelectrofocalization was performed together with the determination of kinetic constants in order to characterize the beta-lactamase, and a polyacrylamide gel electrophoresis in order to observe the profile.


RESULTS
The strain of E. aerogenes 174004/H exhibits a chromosomic beta-lactamase with a pI higher than 9.2 and a decrease in an outer membrane protein of 42 kDa, probably a porine.


CONCLUSIONS
E. aerogenes 174004/H resistance against imipenem is due to an hyperproduction of a chromosomic beta-lactamase with a pI higher than 9.2 and to a 42 kDa decrease of an outer membrane protein expression.
Miró
E
E
Servicio de Microbiología, Hospital de la Santa Creu i Sant Pau, Universitat Autònoma, Barcelona.
Alonso
C
C
Navarro
F
F
Mirelis
B
B
Prats
G
G
D001425:Bacterial Outer Membrane Proteins / Q000032:analysis*; D004754:Enterobacter / Q000737:chemistry / Q000187:drug effects*; D006801:Humans; D015378:Imipenem / Q000494:pharmacology*; D018440:beta-Lactam Resistance; D001618:beta-Lactamases / Q000032:analysis
D001425:Bacterial Outer Membrane Proteins; D015378:Imipenem; D001618:beta-Lactamases
Resistencia al imipenem en Enterobacter aerogenes.