The main objectives were to describe two bla_KPC-2 plasmids recovered from Pseudomonas aeruginosa isolates belonging to the ST654 and ST235 high-risk clones, and to compare with complete sequences of bla_KPC-2 harbouring plasmids available in public databases. Antimicrobial susceptibility was determined according to CLSI (Clinical and Laboratory Standards Institute) guidelines. Genomes were sequenced using an Illumina MiSeq platform, and bla_KPC-2 plasmid sequences were achieved using MinION platform. Sequences were analysed using Unicycler and RAST. In silico predictions of the isolates sequence type (ST), antimicrobial resistance genes, plasmid replicon typing and MOB relaxases were fulfilled using bioinformatics tools. PA_2047 and PA_HdC isolates corresponded to the high-risk clones ST654 and ST235, respectively. The carbapenem resistance was mediated by KPC-2. Both bla_KPC-2 harbouring plasmids, pPA_2047 and pPA_HdC, were different among them, non-conjugative and untypable by PlasmidFinder. pPA_2047 presented high identity with a Pae-13 plasmid, and these both located bla_KPC-2 in Tn4401b isoform. pPA_HdC displayed a novel architecture, and the genetic context of bla_KPC-2 was original. Besides the bla_KPC-2 gene, resistance genes to aminoglycosides and quinolones were detected, including the novel phosphotransferase CrpP in PA_HdC. This study expands the limited knowledge about the molecular epidemiology of bla_KPC-2 in P. aeruginosa from Latin America. Two novel plasmids harbouring bla_KPC-2 were described that were untypable by their incompatibility group. The plasmid recovered from P. aeruginosa PA_HdC (ST235) displayed a novel architecture and an original context for bla_KPC-2. On the other hand, the genetic platform carrying bla_KPC-2 in P. aeruginosa PA_2047 (ST654) seems to a be a classical one.

MDR Klebsiella pneumoniae ST307 is a high-risk clone, whose genetic features contribute to its adaptation to hospital environments and the human host. This study describes the emergence and clonal dissemination of K. pneumoniae ST307, recovered during November 2018 to February 2019 in a hospital in Buenos Aires city, which concurrently harbored KPC-3 and NDM-1. These isolates were resistant to all β-lactams and to the ceftazidime/avibactam combination. Molecular studies showed that bla_KPC-3 was located in Tn4401a platform, while bla_NDM-1 was surrounded upstream by ISKpn14 followed by a partial sequence of ISAba125 and downstream by bleMBL-trpF, located in a 145.5kb conjugative plasmid belonging to the Inc A/C group. The dissemination of K. pneumoniae ST307 isolates co-producing KPC-3 and NDM-1 could lead to a worrisome scenario due to the remarkable features of this clone and its resistance profile.

Metallo-β-lactamases (MBL) producing Pseudomonas aeruginosa isolates have been well characterized. Quinolones are commonly used in the treatment of carbapenem-resistant P. aeruginosa infections; however, data about PMQR in this species are scarce. The objective of this study was to report the simultaneous presence of qnrS and blaVIM-11 in P. aeruginosa, and to characterize the qnrS-harboring plasmid. Thirty-eight carbapenem-resistant P. aeruginosa isolates were recovered from a hospital in Buenos Aires during 2012. Screening for MBL was assessed by the double disk synergy test using EDTA and carbapenem discs. Plasmid DNA extraction was performed by a method using phenol-chloroform. PCR followed by sequencing was carried out to determine each MBL and PMQR allele. PCR-BseGI-RFLP was performed to detect aac-(6')-Ib-cr. The gyrA-QRDR was sequenced in those PMQR-harboring isolates. Plasmid incompatibility groups and addiction systems were characterized by PCR. The PMQR-carrying plasmid was sequenced using Illumina technology, annotated using RAST and manually curated. Eleven/38 isolates were VIM producers (blaVIM-2 and blaVIM-11) while 1/38 harbored blaIMP-13. One isolate harbored blaVIM-11 and the PMQR qnrS1; however, both markers were located in different plasmids. The qnrS1-harboring plasmid (pP6qnrS1) was 117945bp in size, presented 154 CDS and corresponded to the IncR group. In addition to qnrS1, it harbored several aminoglycoside resistance markers. Although pP6qnrS1 was non-conjugative, it presented an oriT which made it possible for this plasmid to be transferable. This is the first report on P. aeruginosa carrying both blaVIM-11 and qnrS1, plus the first detection of an IncR plasmid in Argentina.

Ten IMP-8-producing Escherichia coli isolates were recovered from surveillance cultures of a neonatal intensive care unit; eight of the isolates were clonally related. A 168.2-kb bla _IMP-8 plasmid was fully sequenced, and it corresponded to the recently described IncA/C1-ST13 plasmid. This plasmid was detected in all isolates, even in those that were not clonally related. One unrelated isolate was also resistant to colistin and positive for mcr-1 . This marker was located in a 62.7-kb IncI2 plasmid, which was also fully sequenced.

In the last decade Achromobacter spp. has been associated with chronic colonization in patients with cystic fibrosis (CF). Although Achromobacter xylosoxidans is the most frequent species recovered within this genus, other species such as A. ruhlandii have also been reported in these patients. Descriptions of mobile elements are scarce in Achromobacter and none of them have been originated in A. ruhlandii. The aim of this study was to report the full characterization of a plasmid which was maintained in four clonally related A. ruhlandii isolates. Between 2013 and 2015, nine A. ruhlandii isolates were recovered from a pediatric patient with CF at a hospital in Buenos Aires. Four selected clonally related isolates were sequenced by Illumina MiSeq, annotated using RAST and manually curated. The presence of a unique plasmid of 34096-bp and 50 CDS was observed in the four isolates, displaying only 1 nucleotide substitution translated into one amino acid change among them. These plasmids have a class 1 integron containing the aac-(6')-Ib gene, a mercury resistance operon region and the relE/stbE toxin/antitoxin system. Plasmids showed 79% similarity and 99% identity with pmatvim-7 from Pseudomonas aeruginosa. This is the first full description and characterization of a plasmid from A. ruhlandii which was maintained over time.