Variation in selected regions of blaTEM genes and promoters in Haemophilus influenzae.

OBJECTIVES To determine if the TEM beta-lactamases of Haemophilus influenzae are TEM-1 or derivatives thereof and associated exclusively with the overlapping Pa/Pb promoters. METHODS Single nucleotide specific PCR was used to discriminate the polymorphic nucleotides at positions 32 and 317 of the bla(TEM) genes of a collection of TEM-positive strains. RESULTS All bla(TEM) genes were found to be bla(TEM-1) or derivatives thereof and none bla(TEM-2). The bla(TEM) genes were associated with the P3 promoter, the Pa/Pb promoters or a novel promoter produced as a result of a 135 bp deletion and a G162T substitution. CONCLUSIONS The genetic features of bla(TEM) genes in H. influenzae are different from those in Enterobacteriaceae and more variable than previously recognized.