Dataset Information

The genomic characterization of carbapenem-resistant Serratia marcescens at a tertiary hospital in South Africa.

ABSTRACT:

Background

Serratia marcescens is an opportunistic nosocomial pathogen, and recent reports have highlighted the rapid increase in multidrug resistance in this organism. There is a paucity in genomic data for carbapenem-resistant S. marcescens (CRSM).

Methods

A retrospective cohort study describing laboratory-confirmed CRSM from a tertiary academic hospital in Cape Town, South Africa, for the period 2015-20, was performed. Stored CRSM and contemporary isolates were submitted for WGS using Illumina MiSeq, with the Nextera DNA Flex Library Preparation Kit. Sequence data were analysed in-house using srst2 and Tychus, and CRSM and contemporary isolates were compared.

Results

Twenty-one CRSM and four contemporary isolates were sequenced and analysed. Twenty-four different resistance genes were identified, with all isolates having at least two resistance genes, and seventeen isolates harbouring three or more genes. This correlated well with phenotypic results. The bla_OXA-48-like carbapenemase was the most common carbapenemase identified, in 86% (18/21) of CRSM. A core SNP difference tree indicated that the CRSM could be grouped into three clusters. Eleven isolates had shared plasmids. Several genes and SNPs were identified in the CRSM, which may putatively augment virulence, but this requires further functional characterization.

Conclusions

A diverse resistome was observed in CRSM, which was also reflected phenotypically, with bla_OXA-48-like the most commonly carbapenemase. Though distinct clusters were observed, no clonality was noted, and a limited number of isolates shared plasmids. This study provides genomic data for emerging CRSM and highlights the importance of ongoing genomic surveillance to inform infection prevention control and antimicrobial stewardship initiatives.

SUBMITTER: Overmeyer AJ

PROVIDER: S-EPMC10368080 | biostudies-literature | 2023 Aug

REPOSITORIES: biostudies-literature

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Publications

The genomic characterization of carbapenem-resistant <i>Serratia marcescens</i> at a tertiary hospital in South Africa.

Overmeyer Amanda Julia AJ Prentice Elizabeth E Brink Adrian A Lennard Katie K Moodley Clinton C

JAC-antimicrobial resistance 20230725 4

<h4>Background</h4>Serratia marcescens is an opportunistic nosocomial pathogen, and recent reports have highlighted the rapid increase in multidrug resistance in this organism. There is a paucity in genomic data for carbapenem-resistant <i>S. marcescens</i> (CRSM).<h4>Methods</h4>A retrospective cohort study describing laboratory-confirmed CRSM from a tertiary academic hospital in Cape Town, South Africa, for the period 2015-20, was performed. Stored CRSM and contemporary isolates were submitted ...[more]

PMID: 37497336

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Project description:Serratia marcescens has emerged as an important opportunistic pathogen responsible for nosocomial and severe infections. Here, we determined phenotypic and molecular characteristics of 54 S. marcescens isolates obtained from patient samples from intensive-care-unit (ICU) and neonatal intensive-care-unit (NIUC) of a Brazilian tertiary hospital. All isolates were resistant to beta-lactam group antibiotics, and 92.6% (50/54) were not susceptible to tigecycline. Furthermore, 96.3% showed intrinsic resistance to polymyxin E (colistin), a last-resort antibiotic for the treatment of infections caused by MDR (multidrug-resistant) Gram-negative bacteria. In contrast, high susceptibility to other antibiotics such as fluoroquinolones (81.5%), and to aminoglycosides (as gentamicin 81.5%, and amikacin 85.2%) was found. Of all isolates, 24.1% were classified as MDR. The presence of resistance and virulence genes were examined by PCR and sequencing. All isolates carried KPC-carbapenemase (bla KPC ) and extended spectrum beta-lactamase bla TEM genes, 14.8% carried bla OXA- 1, and 16.7% carried bla CTX-M- 1 group genes, suggesting that bacterial resistance to β-lactam antibiotics found may be associated with these genes. The genes SdeB/HasF and SdeY/HasF that are associated with efflux pump mediated drug extrusion to fluoroquinolones and tigecycline, respectively, were found in 88.9%. The aac(6')-Ib-cr variant gene that can simultaneously induce resistance to aminoglycoside and fluoroquinolone was present in 24.1% of the isolates. Notably, the virulence genes to (i) pore-forming toxin (ShlA); (ii) phospholipase with hemolytic and cytolytic activities (PhlA); (iii) flagellar transcriptional regulator (FlhD); and (iv) positive regulator of prodigiosin and serratamolide production (PigP) were present in 98.2%. The genetic relationship among the isolates determined by ERIC-PCR demonstrated that the vast majority of isolates were grouped in a single cluster with 86.4% genetic similarity. In addition, many isolates showed 100% genetic similarity to each other, suggesting that the S. marcescens that circulate in this ICU are closely related. Our results suggest that the antimicrobial resistance to many drugs currently used to treat ICU and NIUC patients, associated with the high frequency of resistance and virulence genes is a worrisome phenomenon. Our findings emphasize the importance of active surveillance plans for infection control and to prevent dissemination of these strains.