First Characterization in Tunisia of a TEM-15,Extended-Spectrum β -Lactamase-Producing Klebsiella pneumoniae Isolate

Abstract

Klebsiella pneumoniae CH0905 strain exhibiting high-level cefotaxime resistance was isolated from a stool culture in the intensive care unit. The resistance gene responsible was shown to be located on a conjugative 60-kb plasmid designated pCH0905. The minimum inhibitory concentration (MIC) values for cefotaxime and ceftazidime of the original isolate and the transconjugates were 256 μg/ml. Isoelectric focusing of a protein preparation from the K. pneumoniae strain showed β-lactamases with the pI values of 7.6 and 6.3. A 1,080-bp fragment amplified with PCR was cloned into the pGEM-T Easy vector. The nucleotide sequence of the complete 1,080 bp was determined. Sequence analysis revealed that the bla_TEM gene of pCH0905 differed from bla_TEM-1 by two mutations, leading to the following amino acid substitutions: the glutamic acid residue at position 104 by lysine and the glycine residue at position 238 by serine (Ambler numbering). The association of these two mutations was described previously in TEM-15 β-lactamase, but this is the first detection of this enzyme in Tunisia.