Genetic and biochemical analysis of a novel Ambler class A β-Lactamase responsible for cefoxitin resistance in Bacteroides species.

ECU Author/Contributor (non-ECU co-authors, if there are any, appear on document)

Anita C. Parker (Creator)

C. Jeffrey Smith (Creator)

Institution

East Carolina University (ECU )

Web Site: http://www.ecu.edu/lib/

Abstract: A clinical isolate of Bacteroides vulgatus was resistant to tetracycline clindamycin ampicillin cephaloridine efoxitin and other 13-lactam antibiotics except imipenem. 13-Lactam resistance was mediated by a membraneassociated lavulanate-sensitive cephalosporinase capable of degrading cephalosporins and penicillins. Cefoxitin lso was degraded but at a slow rate. The cefoxitin resistance (Fxr) determinant was cloned from B. ulgatus genomic libraries that were prepared in Escherichia coli and then mated with Bacteroidesfragilis for he identification of Fxr strains. Analysis of B. fragilis strains with the cloned Fxr determinant revealed the resence of a new 13-lactamase protein with the physical and enzymatic properties of the 13-lactamase found in he original B. vulgatus isolate. The 13-lactamase gene (cftA) was subcloned on a 2.2-kb DraI-HindIII fragment nd the nucleotide sequence was determined. These results showed that cfxA encoded a protein of 321 amino cids and 35 375 molecular weight. Mutant strains in which the cfxA structural gene was disrupted by nsertional inactivation lost both Fxr and 13-lactamase activity. Comparison of CfxA with other f3-lactamases howed a relationship with the active-site serine 13-lactamases in the Ambler molecular class A although CfxA ad apparently diverged significantly. This was exemplified by the substitution in CfxA at 13 of 25 amino acid esidues previously identified as being invariant in class A 13-lactamases. These results suggest that CfxA may epresent a new class A homology group which diverged very early. Originally published Antimicrobial Agents and Chemotherapy Vol. 37 No. 5 May 1993

Additional Information

Publication

Other

Antimicrobial Agents and Chemotherapy. 37:5(May 1993) p. 1028-1036.

Language: English

Date: 2011

Keywords

B-Lactam resistance, Bacteroides antibotic resistance, Class A beta-lactamases

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