Synergistic effect of imp/ostA and msbA in hydrophobic drug resistance of Helicobacter pylori

Abstract

BackgroundContamination of endoscopy equipment by Helicobacter pylori (H. pylori) frequently occurs after endoscopic examination of H. pylori-infected patients. In the hospital, manual pre-cleaning and soaking in glutaraldehyde is an important process to disinfect endoscopes. However, this might not be sufficient to remove H. pylori completely, and some glutaraldehyde-resistant bacteria might survive and be passed to the next patient undergoing endoscopic examination through unidentified mechanisms. We identified an Imp/OstA protein associated with glutaraldehyde resistance in a clinical strain, NTUH-C1, from our previous study. To better understand and manage the problem of glutaraldehyde resistance, we further investigated its mechanism.ResultsThe minimal inhibitory concentrations (MICs) of glutaraldehyde andexpression of imp/ostA RNA in 11 clinical isolates from the National Taiwan University Hospital were determined. After glutaraldehyde treatment, RNA expression in the strains with the MICs of 4–10 μg/ml was higher than that in strains with the MICs of 1–3 μg/ml. We examined the full-genome expression of strain NTUH-S1 after glutaraldehyde treatment using a microarray and found that 40 genes were upregulated and 31 genes were downregulated. Among the upregulated genes, imp/ostA and msbA, two putative lipopolysaccharide biogenesis genes, were selected for further characterization. The sensitivity to glutaraldehyde or hydrophobic drugs increased in both of imp/ostA and msbA single mutants. The imp/ostA and msbA double mutant was also hypersensitive to these chemicals. The lipopolysaccharide contents decreased in individual imp/ostA and msbA mutants and dramatically reduced in the imp/ostA and msbA double mutant. Outer membrane permeability assay demonstrated that the imp/ostA and msbA double mutation resulted in the increase of outer membrane permeability. Ethidium bromide accumulation assay demonstrated that MsbA was involved in efflux of hydrophobic drugs.ConclusionThe expression levels of imp/ostA and msbA were correlated with glutaraldehyde resistance in clinical isolates after glutaraldehyde treatment. Imp/OstA and MsbA play a synergistic role in hydrophobic drugs resistance and lipopolysaccharide biogenesis in H. pylori.

Helicobacter pylori and Antibiotic Resistance, A Continuing and Intractable Problem

“…ABC transporters can couple ATP hydrolysis and substrate transport across the membrane. The synergistic effect of MsbA and imp/ostA with respect to the efflux of hydrophobic drugs is easily detectable and is related to the MDR of H. pylori [113]. In fact, MsbA conferred an 86-fold resistance to erythromycin when expressed in lactobacillus [112].…”

“…In fact, MsbA conferred an 86-fold resistance to erythromycin when expressed in lactobacillus [112]. The synergistic effect of MsbA and imp/ostA with respect to the efflux of hydrophobic drugs is easily detectable and is related to the MDR of H. pylori [113]. Both msbA and imp/ostA mutants display increased susceptibility to hydrophobic drugs and to glutaraldehyde.…”

The Challenge of Efflux-Mediated Antibiotic Resistance in Gram-Negative Bacteria

“…Inactivation of the ABC-type transporter MsbA rendered the strain more susceptible to erythromycin and glutaraldehyde. MsbA also interplays synergistically with the glutaraldehyde-resistant protein Ost/Imp to enhance hydrophobic drug resistance and LPS biogenesis (691). Various types of putative drug transporters (e.g., 2 RND pumps, 1 MFS pump, 2 MATE pumps, 4 SMR pumps, and 1 ABC pump) were also identified in Helicobacter cinaedi, a pathogen increasingly known for infections in immunocompromised patients (692).…”

Profile of Expression of Helicobacter pyloriγ‐Glutamyltranspeptidase

“…Although target genes regulated by these two‐component systems have been identified by several studies [14–16], no HP1118 gene involvement has been reported. In addition, previous studies employing a whole genome expression profiling method with microarray did not observe significant alteration of expression of HP1118 gene under different pH [15–18] and growth phase [19], except for a study which observed down regulation of this gene by treatment with glutaraldehyde [20], a disinfectant substance which would not exist at significant level under physiological conditions in vivo. Our results together with the findings of these previous reports indicate that H. pylori GGT protein is constitutively expressed under various in vivo conditions at all times.…”