the TEM-34 IRT ОІ-lactamase was harboured in a в€ј5.5 kb plasmid.Д¬ONCLUSIONS: Clinical isolates of H. The TnA transposons of two ОІ-lactamase-positive isolates (TEM-1 and TEM-182) were inserted between the tfc20 and tfc21 genes, typically associated with integrative and conjugative elements in Haemophilus spp.

In two ОІ-lactamase-positive isolates without PBP3 mutations, the inhibitor-resistant TEM (IRT) ОІ-lactamases TEM-34 and the novel TEM-182 were detected and carried by a TnA transposon of the Tn2 type both isolates had an amoxicillin/clavulanic acid MIC of в‰Ґ8 mg/L. The additional Ser385Thr substitution (III-like group) may confer decreased susceptibility to cefotaxime, cefixime and aztreonam, as in Haemophilus influenzae. gBLNAR isolates had MIC90 values 4- to 16-fold higher than gBLNAS isolates for ampicillin, amoxicillin/clavulanic acid, cefuroxime, cefotaxime and cefixime, and the most common PBP3 mutation was Asn526Ser. No resistance mechanisms were identified in the susceptible control group (gBLNAS).

RESULTS: Of the 20 non-susceptible isolates, 8 produced TEM ОІ-lactamase (gBLPAR), 7 had mutations in the transpeptidase domain of the ftsI gene related to decreased susceptibility to ОІ-lactams (gBLNAR) and 5 had both resistance mechanisms (gBLPACR). In this collection, the presence of amino acid substitutions in the transpeptidase domain of penicillin-binding protein 3 (PBP3), ОІ-lactamase production and the surrounding genetic regions of blaTEM genes in selected isolates were analysed. parainfluenzae with decreased susceptibility to aminopenicillins were examined and compared with a control group of 20 fully susceptible isolates.

OBJECTIVES: To determine the mechanisms of resistance to ОІ-lactam antibiotics in clinical isolates of Haemophilus parainfluenzae.

Pbp3 mutation