Relative Strengths and Regulation of Different Promoter-Associated Sequences for Various <b><i>bla</i></b>_SHV Genes and Their Relationships to β-Lactam Resistance

Abstract

Aims: This work investigated the relative strengths of different bla_SHV promoter-associated sequences and their regulation function in bla_SHV expression and β-lactam resistance. Methods: Recombinant plasmids with the promoter-associated sequences (P-W, P-S, P-IS, and P-WPD), tac promoter, and combined fragments of promoter and bla_SHV were separately constructed and transformed into Escherichia coli DH5α. The relative strengths of the promoters indicated by the intensities of green fluorescent protein and the mRNA expression levels of bla_SHV were compared. The minimum inhibitory concentration and extended spectrum β-lactamase phenotypes were evaluated. Results: The relative strengths were ranked as P-tac > P-WPD > P-IS > P-S > P-W. The mRNA expression and β-lactam resistance levels of the different promoter-associated sequence groups were generally consistent with the strength rank, but the extent of gfp and bla_SHV mRNA levels varied significantly in each group. The β-lactam resistance levels were inconsistent with the strength rank in certain bla_SHV groups. In relation to the different promoter-associated sequences, bla_SHV-ESBLs displayed significantly different change modes of β-lactam resistance compared with bla_{SHV-non-ESBLs}. Conclusion: The mRNA expression and β-lactam resistance of the bla_SHV showed consistencies and inconsistencies with the strengths of the promoter-associated sequences. The mechanisms accounting for these discrepancies need further investigation.

Genome-Based Analysis of Klebsiella spp. Isolates from Animals and Food Products in Germany, 2013–2017

“…ESBL genes were detected in 16 of 94 isolates, but only five isolates with bla CTX-M genes showed resistance to third-generation cephalosporins (ST11, ST13, ST107, ST1017, ST1836). The remaining eleven isolates harbored bla SHV-27 and bla SHV-41 genes, but also a base-pair substitution in their promoter sequence, that has been described to be associated with a weak bla gene expression and non-ESBL phenotype [ 40 ]. Resistance to colistin was detected in only one (ST11, pig) of the 94 Klebsiella spp.…”

Piperacillin/tazobactam resistant, cephalosporin susceptibleEscherichia colibloodstream infections are driven by multiple acquisition of resistance across diverse sequence types

“…A number of the isolates were lacking a detectable increase in gene copy number, but had a route to hyperproduction via strong promoters of blaTEM-1 27 or blaSHV-1 40 .…”

“…In silico multi locus sequence typing (MLST), and plasmid replicon typing were also carried out using ARIBA and the MLSTFinder 38 and PlasmidFinder 39 databases, respectively. β-lactamase promoters were identified by constructing databases with promoter sequences for blaTEM-1 27 and blaSHV-1 40 and screening using ARIBA . Copy number was estimated by dividing the sequencing coverage of βlactamase genes by the coverage of the chromosomal single copy gene ampH.…”

Piperacillin-Tazobactam Resistance Mechanisms in Escherichia coli and Identification of a CTX-M-255 β-Lactamase Selectively Conferring Resistance to Penicillin/β-Lactamase Inhibitor Combinations

“…The last isolate co-produced bla TEM-1 and bla TEM-35 the latter being an inhibitor resistant TEM (IRT) enzyme not efficiently inhibited by tazobactam and a well described cause of penicillin/β-lactamase inhibitor resistance (14)(15)(16). Similar to bla TEM-1 hyperproduction, TZP resistance can be caused by hyperproduction of bla SHV-1 due to increased copy number (9) or a stronger promoter (17).…”