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

Chiu HC, Lin TL, Yang JC, Wang JT - BMC Microbiol. (2009)

Bottom Line: 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.Imp/OstA and MsbA play a synergistic role in hydrophobic drugs resistance and lipopolysaccharide biogenesis in H. pylori.

View Article: PubMed Central - HTML - PubMed

Affiliation: Department of Microbiology, National Taiwan University College of Medicine, Taipei City 10051, Taiwan, Republic of China. gaki98@yahoo.com.tw

ABSTRACT

Background: Contamination 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.

Results: The 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 microg/ml was higher than that in strains with the MICs of 1-3 microg/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.

Conclusion: The 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.

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Southern hybridization of Hind III-digested DNA from strains NTUH-S1 and mutants with imp/ostA (left) and msbA (right) probes. Approximately 5 μg of genomic DNA from H. pylori NTUH-S1 and the mutants was digested by Hind III. Hybridization and detection were performed with the DIG Luminescent Detection kit (Roche) according to the manufacturer's instructions.
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Figure 5: Southern hybridization of Hind III-digested DNA from strains NTUH-S1 and mutants with imp/ostA (left) and msbA (right) probes. Approximately 5 μg of genomic DNA from H. pylori NTUH-S1 and the mutants was digested by Hind III. Hybridization and detection were performed with the DIG Luminescent Detection kit (Roche) according to the manufacturer's instructions.

Mentions: We had previously observed that the imp/ostA mutant became more sensitive to glutaraldehyde than wild-type strain [14]. Southern blot hybridizations were performed to confirm that imp/ostA or msbA were absent in the mutants (Fig. 5). We further investigated whether the sensitivities to glutaraldehyde ofisogenic msbA and an imp/ostA, msbA double mutants were altered. The MIC for the msbA single mutant (3.05 ± 0.27 μg/ml) was lower than for wild-type (5.45 ± 0.21 μg/ml) (wild-type vs.msbA single mutant, P = 2.84 × 10-7). For comparison, the MIC for the imp/ostA single mutant (1.40 ± 0.42 μg/ml) was also significantly lower than that of wild-type, as previously reported [14]. Furthermore, the MICs for imp/ostA and msbA double mutant (0.60 ± 0.14 μg/ml) was also significantly lower than that of wild-type and showed the most significant difference (P = 5.77 × 10-10). Complementation of the msbA mutation significantly restored the resistance to glutaraldehyde (Fig. 6A). These results suggested that imp/ostA and msbA were both involved in glutaraldehyde resistance, and the deficiency of these two genes in H. pylori led to hypersensitivity to glutaraldehyde.


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

Chiu HC, Lin TL, Yang JC, Wang JT - BMC Microbiol. (2009)

Southern hybridization of Hind III-digested DNA from strains NTUH-S1 and mutants with imp/ostA (left) and msbA (right) probes. Approximately 5 μg of genomic DNA from H. pylori NTUH-S1 and the mutants was digested by Hind III. Hybridization and detection were performed with the DIG Luminescent Detection kit (Roche) according to the manufacturer's instructions.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC2719649&req=5

Figure 5: Southern hybridization of Hind III-digested DNA from strains NTUH-S1 and mutants with imp/ostA (left) and msbA (right) probes. Approximately 5 μg of genomic DNA from H. pylori NTUH-S1 and the mutants was digested by Hind III. Hybridization and detection were performed with the DIG Luminescent Detection kit (Roche) according to the manufacturer's instructions.
Mentions: We had previously observed that the imp/ostA mutant became more sensitive to glutaraldehyde than wild-type strain [14]. Southern blot hybridizations were performed to confirm that imp/ostA or msbA were absent in the mutants (Fig. 5). We further investigated whether the sensitivities to glutaraldehyde ofisogenic msbA and an imp/ostA, msbA double mutants were altered. The MIC for the msbA single mutant (3.05 ± 0.27 μg/ml) was lower than for wild-type (5.45 ± 0.21 μg/ml) (wild-type vs.msbA single mutant, P = 2.84 × 10-7). For comparison, the MIC for the imp/ostA single mutant (1.40 ± 0.42 μg/ml) was also significantly lower than that of wild-type, as previously reported [14]. Furthermore, the MICs for imp/ostA and msbA double mutant (0.60 ± 0.14 μg/ml) was also significantly lower than that of wild-type and showed the most significant difference (P = 5.77 × 10-10). Complementation of the msbA mutation significantly restored the resistance to glutaraldehyde (Fig. 6A). These results suggested that imp/ostA and msbA were both involved in glutaraldehyde resistance, and the deficiency of these two genes in H. pylori led to hypersensitivity to glutaraldehyde.

Bottom Line: 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.Imp/OstA and MsbA play a synergistic role in hydrophobic drugs resistance and lipopolysaccharide biogenesis in H. pylori.

View Article: PubMed Central - HTML - PubMed

Affiliation: Department of Microbiology, National Taiwan University College of Medicine, Taipei City 10051, Taiwan, Republic of China. gaki98@yahoo.com.tw

ABSTRACT

Background: Contamination 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.

Results: The 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 microg/ml was higher than that in strains with the MICs of 1-3 microg/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.

Conclusion: The 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.

Show MeSH
Related in: MedlinePlus