Molecular analysis of NDM-1-producing enterobacterial isolates from Geneva, Switzerland

Objectives To analyse the mechanisms responsible for decreased susceptibility or resistance to carbapenems in several enterobacterial isolates recovered in 2009-10 in Geneva University Hospitals, Switzerland. Methods PCR and sequencing were used to identify β-lactamases, 16S RNA methylases and plasmid-mediated quinolone resistance genes. The transferable properties of the plasmids were analysed, as well as their plasmid type. The strains were typed by multilocus sequence typing. Results Three patients were found to be positive for NDM-1-producing enterobacterial isolates (one with Escherichia coli and Klebsiella pneumoniae, one with K. pneumoniae only and one with Proteus mirabilis), where NDM-1 stands for New Delhi metallo-β-lactamase-1. The blaNDM-1 carbapenemase gene was detected in all isolates in addition to genes encoding narrow-spectrum β-lactamases (TEM-1, SHV-11, OXA-1, OXA-9 and OXA-10), extended-spectrum β-lactamases (CTX-M-15, CMY-16 and CMY-30), ArmA and quinolone resistance determinants (Qnr). The blaNDM-1 gene was located on conjugative IncA/C- or IncF-type plasmids. Upstream of the blaNDM-1 gene, part of ISAba125, previously identified in NDM-1-negative Acinetobacter baumannii, was found. Downstream of the blaNDM-1 gene, variable sequences were found. Conclusions This work constitutes the first identification of NDM-1 producers in Switzerland. Interestingly, patients from whom these NDM-1-producing isolates were recovered had a link with the Indian subcontinent or the Balkan

A novel IncQ plasmid type harbouring a class 3 integron from Escherichia coli

Objectives To determine the genetic structures at the origin of the mobilization of the extended-spectrum β-lactamase (ESBL) blaGES-1 gene in an Escherichia coli clinical isolate. Methods ESBL-encoding genes and class 1 or class 3 integron-specific motifs were screened. Conjugation experiments were performed to determine whether the plasmid-carrying blaGES-1 gene was self-transferable. Plasmid sequencing was achieved by a primer-walking approach. Results The blaGES-1 gene was located in a class 3 integron. That unusual genetic structure was itself located on an ∼9 kb plasmid, pQ7, which was not self-transferable. Sequence analysis revealed that plasmid pQ7 belonged to a novel subtype of the IncQ group. Conclusions This study identified for the first time the blaGES-1 gene in E. coli and in Switzerland. It describes a novel IncQ-type plasmid subgroup that possesses original features, in particular iteron sequences that constitute a hot spot for integration of foreign DN

Spread of NDM-1-producing enterobacteriaceae in a neonatal intensive care unit in Istanbul, Turkey

Twenty-two consecutive carbapenem-resistant enterobacterial isolates were recovered from patients hospitalized between January and April 2013 in different units at a university hospital in Istanbul, Turkey. These were Klebsiella pneumoniae isolates producing the carbapenemases OXA-48, NDM-1, and KPC-2, Enterobacter cloacae isolates producing NDM-1, and Escherichia coli isolates producing OXA-48. Most of the OXA-48-producing K. pneumoniae and all the NDM-1-producing E. cloacae were clonally related. The NDM-1-producing E. cloacae isolates recovered from a single neonatal intensive care unit corresponded to a single cluster, highlighting the spread of that clone in that setting

Detection of NDM-1-Producing Klebsiella pneumoniae in Kenya▿

Seven carbapenem-resistant NDM-1-positive Klebsiella pneumoniae isolates were recovered from patients hospitalized between 2007 and 2009 in different wards at a referral and tertiary care center in Nairobi. Most of the isolates were obtained from urine. All isolates carried the blaNDM-1 carbapenemase gene previously reported from India, Pakistan, and the United Kingdom. These isolates were clonally related and expressed many other resistance determinants, including β-lactamases CTX-M-15, OXA-1, OXA-9, CMY-6, and aminoglycoside resistance methylase RmtC. This work corresponds to the first report of NDM-1 producers in Africa

A novel IncQ plasmid type harbouring a class 3 integron from Escherichia coli

To determine the genetic structures at the origin of the mobilization of the extended-spectrum beta-lactamase (ESBL) bla(GES-1) gene in an Escherichia coli clinical isolate

Molecular analysis of NDM-1-producing enterobacterial isolates from Geneva, Switzerland

To analyse the mechanisms responsible for decreased susceptibility or resistance to carbapenems in several enterobacterial isolates recovered in 2009-10 in Geneva University Hospitals, Switzerland

To Be or Not to Be an OXA-48 Carbapenemase

Since the first description of OXA-48, more than forty variants have been recovered from Enterobacterales isolates. Whereas some OXA-48-related enzymes have been reported as conferring similar resistance patterns, namely, the hydrolysis of carbapenems and penicillins with very weak or almost no activity against expanded-spectrum cephalosporins, some have reduced carbapenem and temocillin hydrolysis, and others hydrolyze expanded-spectrum cephalosporins and carbapenems only marginally. With such drastic differences in the hydrolytic profile, especially of carbapenems, it becomes urgent to establish hydrolytic cutoffs in order to determine when an OXA-48-like enzyme may be considered as a carbapenemase or not. With this aim, the coefficient of activity for imipenem (kcat/Km) was determined for a total of 30 enzymes, including OXA-48, OXA-48-like natural variants, and OXA-48 synthetic mutants. In addition, six different methods for the detection of carbapenemase-producers were performed. The coefficients of activity for imipenem for all the different enzymes went from 550 mM−1·s−1 to 0.02 mM−1·s−1. In order to match the coefficient of activity results with the biochemical confirmatory tests, we suggest the value of 0.27 mM−1·s−1 as the cutoff above which an OXA-48 variant may be considered a carbapenem-hydrolyzing enzyme