1200. Molecular Epidemiology of Cephalosporinases and Extended Spectrum Beta-lactamases (ESBLs) in Proteus mirabilis Isolates from Croatia: Following the Spread of Resistance Determinants between Long-term Care Facilities and the Community
Session: Poster Abstract Session: Healthcare Epidemiology: MDR-Gram Negative Infections
Friday, October 5, 2018
Room: S Poster Hall
Background: Previous studies on P. mirabilis strains isolated from Croatian healthcare institutions revealed the predominance of TEM-52 extended spectrum beta-lactamase (ESBL), as well as the emergence of plasmid AmpC beta-lactamases. Our aim was to molecularly characterize cefalosporinases in P. mirabilis isolates from long-term care facilities (LTCFs) and to compare their resistance profile and dynamics with community isolates.

Methods: From a total of 3321 P. mirabilis isolates collected from two LCTFs and from outpatients between 2015 and 2017, 1.23% of them were resistant to 3rd generation of cephalosporins. Antimicrobial sensitivity was tested by broth microdilution method. ESBLs and plasmid-mediated AmpC beta-lactamases were detected with phenotypic inhibitor-based tests and polymerase chain reaction (PCR). Antibiotic resistance dissemination and genetic context of bla genes were interrogated by conjugal mating and PCR mapping, respectively. Plasmids were characterized by conjugation and transformation experiments, as well as PCR-based replicon typing.

Results: High level of resistance to amoxicillin, co-amoxiclav, 1st, 2nd and 3rd generation of cephalosporins was found in all isolates. Three isolates tested positive in inhibitor-based test with clavulanic acid, and 38 both in Hodge test and combined disk test with phenylboronic acid – indicating the production of ESBLs and plasmid-mediated AmpC beta-lactamases, respectively. Two ESBL-positive organisms yielded amplicons with primers for CTX-M beta-lactamase of group 1 and one for TEM. All AmpC-positive organisms were identified by PCR as CMY (with an additional TEM). Insert sequence ISEcp-1 was found upstream of blaCMYi blaCTX-M genes. CTX-M positive strains harbored IncK plasmid, whereas AmpC-positive strains were negative for known plasmid types. This is also a first description of P. mirabilis harboring CTX-M-15 beta-lactamase in Croatia.

Conclusion: Our study showed the persistence of CMY beta-lactamases in one LTCF, but also the dissemination of characteristic resistance determinants to another LTCF and the community. Similar to some other studies, there was a clear trend of cephalosporinase dynamic switch from TEM variants to CMY and CTX-M, with impending consequences for treatment decisions.

Tomislav Mestrovic, MD, PhD1,2, Amarela Lukic-Grlic, MD, PhD3,4, Maja Bogdan, MD5, Daniela Bandic-Pavlovic, MD, PhD6, Gordana Cavric, MD, PhD7, Domagoj Drenjancevic, MD, PhD8,9, Katherina Bernardette Sreter, MD10, Ana Bencic, MD in training4, Sanda Sardelic, MD, PhD11 and Branka Bedenic, MD, PhD4,6, (1)Clinical Microbiology and Parasitology Unit, Polyclinic Dr. Zora Profozic, Zagreb, Croatia, (2)University Centre Varazdin, University North, Varazdin, Croatia, (3)Department of Laboratory Diagnostics, Children’s Hospital Zagreb, Zagreb, Croatia, (4)University of Zagreb, School of Medicine, Zagreb, Croatia, (5)Microbiology Service, Institute of Public Health for the Osijek-Baranja County, Osijek, Croatia, (6)University Hospital Centre Zagreb, Zagreb, Croatia, (7)Internal Medicine Department, Clinical Hospital Merkur, Zagreb, Croatia, (8)Josip Juraj Strossmayer University of Osijek, School of Medicine, Osijek, Croatia, (9)Clinical Hospital Centre Osijek, Osijek, Croatia, (10)Clinical Hospital Centre "Sestre Milosrdnice", Zagreb, Croatia, (11)Clinical Hospital Centre Split, Split, Croatia

Disclosures:

T. Mestrovic, None

A. Lukic-Grlic, None

M. Bogdan, None

D. Bandic-Pavlovic, None

G. Cavric, None

D. Drenjancevic, None

K. B. Sreter, None

A. Bencic, None

S. Sardelic, None

B. Bedenic, None

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