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Clonal outbreak caused by VIM-4-producing Proteus mirabilis in a Greek tertiary-care hospital
Efthymia Protonotariou1, Aggeliki Poulou1, Lida Politi2
1Department of Microbiology, AHEPA University Hospital, Aristotle University of Thessaloniki, S. Kiriakidi 1, 546 36, Thessaloniki, Greece.
Abstract:
Carbapenem-resistant Enterobacterales have become a major public-health issue worldwide. Here we report an outbreak caused by a clonal multidrug-resistant Proteus mirabilis strain producing VIM-4 metallo-β-lactamase (MBL) and TEM-2 β-lactamase in a Greek tertiary-care hospital. From July 2015 to February 2016, 27 imipenem-resistant P. mirabilis isolates were recovered from 14 patients hospitalised in two intensive care units (ICUs) and the internal medicine department in AHEPA University Hospital, Thessaloniki. The isolates were either susceptible or resistant to meropenem and were resistant to all remaining β-lactams except aztreonam. Phenotypic and molecular analysis revealed that all of the isolates harboured a blaVIM-4 MBL gene. Resistome analysis of a representative isolate showed the presence of an IncQ1 plasmid harbouring the blaVIM-4 carbapenemase and blaTEM-2 β-lactamase genes among resistance genes coding for resistance to β-lactams, aminoglycosides, trimethoprim, sulfonamides and lincosamides. Genotyping by pulsed-field electrophoresis (PFGE) revealed that the isolates were epidemiologically related. After recovery of the index carbapenemase-producing P. mirabilis clinical isolate, infection control measures were intensified in the affected departments. Rectal sampling for carbapenem-resistant bacteria was initiated on a weekly basis among patients admitted to the general ICU. The outbreak was finally interrupted 6 months later in February 2016. This is the first documentation of the blaVIM-4 MBL gene in P. mirabilis as well as the first hospital outbreak caused by a MBL-producing P. mirabilis strain.
Insights
A multidrug-resistant Proteus mirabilis strain producing VIM-4 metallo-β-lactamase caused a hospital outbreak in Greece. Enhanced infection control measures successfully interrupted the spread of this carbapenem-resistant bacteria.
Area of Science:
- Clinical Microbiology
- Infectious Diseases
- Molecular Epidemiology
Background:
- Carbapenem-resistant Enterobacterales (CRE) pose a significant global public health threat.
- Proteus mirabilis is increasingly recognized as a source of carbapenem resistance.
Purpose of the Study:
- To report the first hospital outbreak caused by a metallo-β-lactamase (MBL)-producing Proteus mirabilis strain.
- To characterize the genetic basis and epidemiological spread of the outbreak strain.
Main Methods:
- Phenotypic and molecular analyses (including resistome analysis and pulsed-field gel electrophoresis (PFGE)) were used to characterize the Proteus mirabilis isolates.
- Surveillance and infection control measures were implemented in response to the outbreak.
Main Results:
- A clonal outbreak of multidrug-resistant Proteus mirabilis producing VIM-4 MBL and TEM-2 β-lactamase occurred in a Greek hospital from July 2015 to February 2016.
- All 27 imipenem-resistant isolates harbored the blaVIM-4 gene, located on an IncQ1 plasmid along with blaTEM-2 and other resistance genes.
- PFGE confirmed the epidemiological relatedness of the isolates, and intensified infection control measures successfully interrupted the outbreak.
Conclusions:
- This study documents the first hospital outbreak caused by a VIM-4 MBL-producing Proteus mirabilis strain.
- The findings highlight the emergence of carbapenem resistance in P. mirabilis and the importance of robust infection control strategies to manage such outbreaks.