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Antimicrobial Agents and Chemotherapy, June 2000, p. 1499-1505, Vol. 44, No. 6
0066-4804/00/$04.00+0
Copyright © 2000, American Society for Microbiology. All rights reserved.

A Novel Complex Mutant beta -Lactamase, TEM-68, Identified in a Klebsiella pneumoniae Isolate from an Outbreak of Extended-Spectrum beta -Lactamase-Producing Klebsiellae

Janusz Fiett,1 Andrzej Pałucha,2 Beata Miaczynska,3 Maria Stankiewicz,3 Hanna Przondo-Mordarska,3 Waleria Hryniewicz,1 and Marek Gniadkowski1,*

Sera & Vaccines Central Research Laboratory, 00-725 Warsaw,1 Institute of Biochemistry and Biophysics, 02-106 Warsaw,2 and Department of Microbiology, Wrocław Medical University, 50-368 Wrocław,3 Poland

Received 29 September 1999/Returned for modification 31 January 2000/Accepted 27 March 2000

Twenty-two Klebsiella pneumoniae and two K. oxytoca extended-spectrum beta -lactamase (ESBL)-producing isolates were collected in 1996 from patients in two pediatric wards of the University Hospital in Wrocław, Poland. Molecular typing has revealed that the K. pneumoniae isolates represented four different epidemic strains. Three kinds of enzymes with ESBL activity (pI values of 5.7, 6.0, and 8.2) were identified. The pI 6.0 beta -lactamases belonged to the TEM family, and sequencing of the blaTEM genes amplified from representative isolates revealed that these enzymes were TEM-47, previously identified in K. pneumoniae isolates from pediatric hospitals in Łódz and Warsaw. One of the TEM-47-producing strains from Wrocław was very closely related to the isolates from the other cities, and this indicated countrywide spread of the epidemic strain. The pI 5.7 beta -lactamase was produced by a single K. pneumoniae isolate for which, apart from oxyimino-beta -lactams, the MICs of beta -lactam-inhibitor combinations were also remarkably high. Sequencing revealed that this was a novel TEM beta -lactamase variant, TEM-68, specified by the following combination of mutations: Gly238Ser, Glu240Lys, Thr265Met, and Arg275Leu. The new enzyme has most probably evolved from TEM-47 by acquiring the single substitution of Arg275, which before was identified only twice in enzymes with inhibitor resistance (IR) activity. TEM-68 was shown to be a novel complex mutant TEM beta -lactamase (CMT-2) which combines strong ESBL activity with relatively weak IR activity and, when expressed in K. pneumoniae, is able to confer high-level resistance to a wide variety of beta -lactams, including inhibitor combinations. This data confirms the role of the Arg275Leu mutation in determining IR activity and documents the first isolation of K. pneumoniae producing the complex mutant enzyme.

* Corresponding author. Mailing address: Sera & Vaccines Central Research Laboratory, ul. Chelmska 30/34, 00-725 Warsaw, Poland. Phone: 48 22 841 33 67. Fax: 48 22 841 29 49. E-mail: marekg{at}ibbrain.ibb.waw.pl.

Antimicrobial Agents and Chemotherapy, June 2000, p. 1499-1505, Vol. 44, No. 6
0066-4804/00/$04.00+0
Copyright © 2000, American Society for Microbiology. All rights reserved.


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Copyright © 2000 by the American Society for Microbiology. All rights reserved.