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Antimicrobial Agents and Chemotherapy, July 2000, p. 1878-1886, Vol. 44, No. 7
0066-4804/00/$04.00+0
Copyright © 2000, American Society for Microbiology. All rights reserved.

Molecular and Biochemical Heterogeneity of Class B Carbapenem-Hydrolyzing beta -Lactamases in Chryseobacterium meningosepticum

Samuel Bellais, Daniel Aubert, Thierry Naas, and Patrice Nordmann*

Service de Bactériologie-Virologie, Hôpital de Bicêtre, Assistance Publique/Hôpitaux de Paris, Faculté de Médecine Paris-Sud, 94275 Le Kremlin-Bicêtre Cedex, France

Received 4 October 1999/Returned for modification 14 February 2000/Accepted 21 April 2000

Although the carbapenem-hydrolyzing beta -lactamase (CHbeta L) BlaB-1 is known to be in Chryseobacterium meningosepticum NCTC 10585, a second CHbeta L gene, blaGOB-1, was cloned from another C. meningosepticum clinical isolate (PINT). The G+C content of blaGOB-1 (36%) indicated the likely chromosomal origin of this gene. Its expression in Escherichia coli DH10B yields a mature CHbeta L with a pI of 8.7 and a relative molecular mass of 28.2 kDa. In E. coli, GOB-1 conferred resistance to narrow-spectrum cephalosporins and reduced susceptibility to ureidopenicillins, broad-spectrum cephalosporins, and carbapenems. GOB-1 had a broad-spectrum hydrolysis profile including penicillins and cephalosporins (but not aztreonam). The catalytic efficiency for meropenem was higher than for imipenem. GOB-1 had low amino acid identity with the class B CHbeta Ls, sharing 18% with the closest, L-1 from Stenotrophomonas maltophilia, and only 11% with BlaB-1. Most of the conserved amino acids that may be involved in the active site of CHbeta Ls (His-101, Asp-103, His-162, and His-225) were identified in GOB-1. Sequence heterogeneity was found for GOB-1-like and BlaB-1-like beta -lactamases, having 90 to 100% and 86 to 100% amino acid identity, respectively, among 10 unrelated C. meningosepticum isolates. Each isolate had a GOB-1-like and a BlaB-1-like gene. The same combination of GOB-1-like and BlaB-1-like beta -lactamases was not found in two different isolates. C. meningosepticum is a bacterial species with two types of unrelated chromosome-borne class B CHbeta Ls that can be expressed in E. coli and, thus, may represent a clinical threat if spread in gram-negative aerobes.


* Corresponding author. Mailing address: Service de Bactériologie-Virologie, Hôpital de Bicêtre, 78 rue du Général Leclerc, 94275 Le Kremlin-Bicêtre Cedex, France. Phone: 33 1 45 21 36 32. Fax: 33 1 45 21 63 40. E-mail: nordmann.patrice{at}bct.ap-hop-paris.fr.


Antimicrobial Agents and Chemotherapy, July 2000, p. 1878-1886, Vol. 44, No. 7
0066-4804/00/$04.00+0
Copyright © 2000, American Society for Microbiology. All rights reserved.



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