Dataset Information

Impact of Inducible bla_DHA-1 on Susceptibility of Klebsiella pneumoniae Clinical Isolates to LYS228 and Identification of Chromosomal mpl and ampD Mutations Mediating Upregulation of Plasmid-Borne bla_DHA-1 Expression.

ABSTRACT: Twenty-three Klebsiella pneumoniae (bla_DHA-1) clinical isolates exhibited a range of susceptibilities to LYS228, with MICs of ≥8 μg/ml for 9 of these. Mutants with decreased susceptibility to LYS228 and upregulated expression of bla_DHA-1 were selected from representative isolates. These had mutations in the chromosomal peptidoglycan recycling gene mpl or ampD Preexisting mpl mutations were also found in some of the clinical isolates examined, and these had strongly upregulated expression of bla_DHA-1.

SUBMITTER: Jones AK

PROVIDER: S-EPMC6153798 | biostudies-literature | 2018 Oct

REPOSITORIES: biostudies-literature

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Publications

Impact of Inducible blaDHA-1 on Susceptibility of Klebsiella pneumoniae Clinical Isolates to LYS228 and Identification of Chromosomal mpl and ampD Mutations Mediating Upregulation of Plasmid-Borne blaDHA-1 Expression.

Jones Adriana K AK Ranjitkar Srijan S Lopez Sara S Li Cindy C Blais Johanne J Reck Folkert F Dean Charles R CR

Antimicrobial agents and chemotherapy 20180924 10

Twenty-three Klebsiella pneumoniae (blaDHA-1) clinical isolates exhibited a range of susceptibilities to LYS228, with MICs of ≥8 μg/ml for 9 of these. Mutants with decreased susceptibility to LYS228 and upregulated expression of blaDHA-1 were selected from representative isolates. These had mutations in the chromosomal peptidoglycan recycling gene mpl or ampD Preexisting mpl mutations were also found in some of the clinical isolates ...[more]

PMID: 30061296

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Project description:Carbapenem-resistant Klebsiella pneumoniae (CRKP) frequently causes hospital-acquired infections and is associated with high morbidity and mortality. CRKP can have multiple resistance mechanisms and only a few can be routinely detected by commercial molecular or phenotypic assays making surveillance for CRKP particularly challenging. In this report, we identified and characterized an unusual non-carbapenemase-producing CRKP carrying a rare plasmid-borne inducible AmpC gene, blaDHA-1 . The isolate was recovered from blood culture of a 67-year-old female presenting with sepsis post bladder surgery and ureteral stent removal. The primary isolate displayed an indeterminate susceptibility pattern for ceftriaxone by broth microdilution, but was susceptible by disk diffusion with one colony growing within the zone of inhibition. The ceftriaxone resistant colony was sub-cultured and had a minimum inhibitory concentration (MIC) of 2 ug/ml for imipenem (intermediate) and a zone size of 18 mm for ertapenem (resistant), but remained susceptible to cefepime and meropenem. Further phenotypic characterization of this sub-cultured isolate showed carbapenemase activity. Whole genome sequencing (WGS) revealed the presence of two subpopulations of a K. pneumoniae (MLST sequence type 11) from the primary blood culture isolate: one pan-susceptible to beta-lactams tested and the other resistant to the 3rd generation cephalosporins and ertapenem. WGS analysis identified the resistant K. pneumoniae harboring IncFIB(K) and IncR plasmids and the presence of plasmid-borne beta-lactam resistance genes bla OXA-1 and bla DHA-1, an inducible AmpC gene. Additional resistance genes against quinolones (aac(6')-Ib-cr, oqxA, oqB), aminoglycoside (aph(3')-Ia), sulfonamide (sul1), and tetracycline (tet(A)) were also identified. DHA-1 positive K. pneumoniae have been previously identified outside the US, particularly in Asia and Europe, but limited cases have been reported in the United States and may be underrecognized. Our study highlights the importance of using both extended phenotypic testing and WGS to identify emerging resistance mechanisms in clinical Enterobacterales isolates with unusual antimicrobial resistance patterns.

Project description:IncX3 and IncL plasmids have been named as catalysts advancing dissemination of blaOXA-181 and blaOXA-48 genes. However, their impact on the performance of host cells is vastly understudied. Genetic characteristics of blaOXA-48- and blaOXA-181-containing Klebsiella pneumoniae (EFN299), Klebsiella quasipneumoniae (EFN262), and Enterobacter cloacae (EFN743) isolated from clinical samples in a Ghanaian hospital were investigated by whole-genome sequencing. Transfer of plasmids by conjugation and electroporation, plasmid stability, fitness cost, and genetic context of blaOXA-48, blaOXA-181, and blaDHA-1 were assessed. blaOXA-181 was carried on two IncX3 plasmids, an intact 51.5-kb IncX3 plasmid (p262-OXA-181) and a 45.3-kb IncX3 plasmid (p743-OXA-181) without replication protein sequence. The fluoroquinolone-resistant gene qnrS1 region was also excised, and unlike in p262-OXA-181, the blaOXA-181 drug-resistant region was not found on a composite transposon. blaOXA-48 was carried on a 74.6-kb conjugative IncL plasmid with unknown ~10.9-kb sequence insertion. This IncL plasmid proved to be highly transferable, with a conjugation efficiency of 1.8 × 10-2. blaDHA-1 was present on an untypeable 22.2 kb genetic structure. Plasmid stability test revealed plasmid loss rate between 4.3% and 12.4%. The results also demonstrated that carriage of IncX3-blaOXA-181 or IncL-blaOXA-48 plasmids was not associated with any fitness defect, but rather an enhanced competitive ability of host cells. This study underscores the significant contribution of IncX3 and IncL plasmids in the dissemination of resistance genes and their efficient transfer calls for regular monitoring to control the expansion of resistant strains. IMPORTANCE The growing rate of antibiotic resistance is an important global health threat. This threat is exacerbated by the lack of safe and potent alternatives to carbapenems in addition to the slow developmental process of newer and effective antibiotics. Infections by carbapenem-resistant Gram-negative bacteria are becoming almost untreatable, leading to poor clinical outcomes and high mortality rates. OXA-48-like carbapenemases are one of the most widespread carbapenemases accounting for resistance among Enterobacteriaecae. We characterized OXA-48- and OXA-181-producing Enterobacteriaecae to gain insights into the genetic basis and mechanism of resistance to carbapenems. Findings from the study showed that the genes encoding these enzymes were carried on highly transmissible plasmids, one of which had sequences absent in other similar plasmids. This implies that mobile genetic elements are important players in the dissemination of resistance genes. Further characterization of this plasmid is warranted to determine the role of this sequence in the spread of resistance genes.

Dataset Information

Impact of Inducible bla_DHA-1 on Susceptibility of Klebsiella pneumoniae Clinical Isolates to LYS228 and Identification of Chromosomal mpl and ampD Mutations Mediating Upregulation of Plasmid-Borne bla_DHA-1 Expression.

Publications

Impact of Inducible <i>bla</i><sub>DHA-1</sub> on Susceptibility of Klebsiella pneumoniae Clinical Isolates to LYS228 and Identification of Chromosomal <i>mpl</i> and <i>ampD</i> Mutations Mediating Upregulation of Plasmid-Borne <i>bla</i><sub>DHA-1</sub> Expression.

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