Genes encoding ten newly designated OXA-63 group class D β-lactamases identified in strains of the pathogenic intestinal spirochaete Brachyspira pilosicoli

Abstract

The anaerobic spirochaete Brachyspira pilosicoli colonizes the large intestine of birds and mammals, including human beings, and may induce colitis and diarrhoea. B. pilosicoli has a recombinant population structure, and strains show extensive genomic rearrangements and different genome sizes. The resident chromosomal gene bla OXA-63 in B. pilosicoli encodes OXA-63, a narrow-spectrum group IV class D b-lactamase. Genes encoding four OXA-63 variants have been described in B. pilosicoli, and the current study was designed to investigate the distribution and diversity of such genes and proteins in strains of B. pilosicoli. PCRs were used to amplify bla OXA-63 group genes from 118 B. pilosicoli strains from different host species and geographical origins. One primer set was targeted externally to the gene and two sets were designed to amplify internal components. A total of 16 strains (13.6 %) showed no evidence of possessing bla OXA-63 group genes, 44 (37.3 %) had a full gene, 27 (22.9 %) apparently had a gene but it failed to amplify with external primers, and 29 (24.6 %) had only one or other of the two internal components amplified. Based on translation of the nucleotide sequences, ten new variants of the b-lactamase, designated OXA-470 through OXA-479, were identified amongst the 44 strains that had the full gene amplified. The 16 strains lacking bla OXA-63 group genes had a region of 1674 bp missing around where the gene was expected to reside. Despite apparent genomic rearrangements occurring in B. pilosicoli, positive selection pressures for conservation of bla OXA-63 group genes and OXA proteins appear to have been exerted.

Severe Colitis with Portal Venous Gas Caused by <i>Brachyspira pilosicoli</i> Infection

“…If patients are symptomatic after ruling out of other diseases, eradication therapy should be considered. It is common to use metronidazole or amoxicillin as therapeutic agents (1,11,23), but in recent years, the efficacy of penicillin has decreased due to an increase in β-lactamase-producing strains (24).…”

Antimicrobial susceptibility of western Canadian Brachyspira isolates: Development and standardization of an agar dilution susceptibility test method

“…High MICs to ampicillin and amoxicillin + clavulanic acid was observed in B. hyodysenteriae, B. hampsonii and B. pilosicoli. While β-lactams are not used to treat Brachyspira-associated infections, the use of penicillin for treating other infections in pigs may have contributed to the selection of resistance to these drugs in Brachyspira [59][60][61]. Previous studies found that B. pilosicoli with high β-lactam drugs MICs possessed the OXA-63 gene, a class D β-lactamase [59].…”

A review of the current state of antimicrobial susceptibility test methods forBrachyspira

“…Most published studies have focused on the association between single nucleotide polymorphisms (SNPs) in genes encoding ribosomal RNA and ribosomal proteins and increased MIC to drugs that act by inhibiting protein synthesis inhibitors, including macrolides, lincosamides, pleuromutilins, doxycycline, chloramphenicol, and florfenicol (Pringle et al 2004(Pringle et al , 2007Hidalgo et al 2011;Verlinden et al 2011;Hillen et al 2014). Narrow-spectrum ␤-lactamases, including 13 enzymes related to OXA-63, have also been identified in B. pilosicoli (Meziane-Cherif et al 2008;Mortimer-Jones et al 2008;La et al 2015). Differences in intrinsic resistance, even between closely related bacteria, can inform treatment decisions based on accurate organism identification, for example, differences in the intrinsic resistance to vancomycin of Enterococcus gallinarum but not Enterococcus faecalis or E. faecium (CLSI 2017).…”