Ampicillin-Eating, Carbapenem-Resistant, Super-Superbug Pseudomonas sp. MR 02, Isolated from an Indian River, Mahananada, Has Exhaustive Repertoire of Genes to Combat All Classes of Antibiotics and Catabolize β-Lactams for Its Sustenance
33 Pages Posted: 7 Jun 2019More...
Background: Since the discovery of New Delhi metallo-β-lactamase-1 (NDM-1) gene, it was only a matter of time for the carbapenem-resistant superbugs to emerge but the membrane anchoring property and elevated catalytic efficiency of NDM-1 towards ampicillin leading to very high minimum inhibitory concentration (MIC) might render the host bacterium an opportunity to utilize the drug as sole source of carbon, nitrogen, and energy was not known until this study.
Methods: Characterization of a carbapenem-resistant river-water isolate was done following standard protocol. MICs of 14 antibiotics were determined both in presence and absence of phenyl-alanine-β-naphthylamide (PAβN) by broth-micro-dilution method. Growth of MR 02 was measured in minimal medium in presence or absence of 0*4 mM EDTA, supplemented with ampicillin as sole carbon, nitrogen and energy source. The blaNDM-1 gene of MR 02 was cloned in pHSG398and expressed in E coli DH5α. Growth of the recombinant strain was measured in minimal medium supplemented with ampicillin as carbon source. Whole genome sequence of MR 02 was duly annotated.
Findings: Pseudomonas sp. MR 02 is resistant to all classes of antibiotics; the phenotype corroborated with resistance genes and geneclusters in its genome. It was found that activity of blaNDM-1 was primarily responsible for subsistence on ampicillin.
Interpretation: High efficiency inactivation of ampicillin by NDM-1 coupled to its outer-membrane anchorage is the key step to enable βlactam catabolism. The blaNDM-1 gene expressed in E coli DH5α supported subsistence and growth in ampicillin as carbon source. Thus, the ability of the super-superbug MR 02 to consume ampicillin for growth has huge implication in antibiotic-stressed eco-systems.
Funding Statement: Senior research fellowship of the Department of Biotechnology, Government of India (DBT, GOI), is provided to VKR. KG received studentship & thesis grant from DBT, GOI. The consumable-support was derived from both DBT and University of North Bengal grant.
Declaration of Interests: There is no competitive interest to declare.
Keywords: Super-superbug, Pseudomonas sp. MR 02, multiple-antibiotic resistance, HGT, MIC, PAβN, bla PME-1, blaNDM-1, Phenyl acetic acid, amidase, conjugal transfer protein
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