Clonal Relatedness and Conserved Integron Structures in Epidemiologically Unrelated Pseudomonas aeruginosa Strains Producing the VIM-1 Metallo-β-Lactamase from Different Italian Hospitals

Abstract

Three epidemiologically independent Pseudomonas aeruginosa isolates, representative of the first VIM-1 metallo-␤-lactamase producers detected at three different hospitals in northern Italy, were investigated to determine their genomic relatedness and to compare the structures of the genetic supports for the VIM-1 determinants. The three isolates, all of serotype O11, appeared to be clonally related according to the results of genotyping by macrorestriction analysis of genomic DNA by pulsed-field gel electrophoresis and random amplification of polymorphic DNA. Investigation of the genetic support for the bla VIM-1 determinant revealed that it was carried on identical or almost identical integrons (named In70.2 and In70.3) located within a conserved genomic context. The integrons were structurally related to In70 and In110, two plasmid-borne bla VIM-1 -containing integrons from Achromobacter xylosoxidans and Pseudomonas putida isolates, respectively, from the same geographic area (northern Italy) and were found to be inserted close to the res site of a Tn5051-like transposon, different from any of those described previously, that was apparently carried on the bacterial chromosome. The present findings suggest that the three VIM-1-producing isolates are members of the same clonal complex which have been spreading in hospitals in northern Italy since the late 1990s and point to a common ancestry of their bla VIM-1 -containing integrons.

Integrons: Past, Present, and Future

“…All chromosomal class 1 integrons characterized from environmental sources have common terminal sequences. The conserved left-hand breakpoint occurs exactly 107 bp beyond the IntI1 stop codon (34), at the same position where the ISPa7 element inserts into class 1 integrons carried by some P. aeruginosa isolates (128). The right-hand breakpoint is also conserved, occurring 43 bp beyond the final attC element (Fig.…”

Analysis of integrons and associated gene cassettes of metallo-β-lactamase-positive Pseudomonas aeruginosa in Malaysia

“…Determination of fingerprinting patterns of P. aeruginosa was carried out by RAPD analysis using primer 272 (Riccio et al, 2005). The RAPD mixture (25 ml) was composed of 100 ng genomic DNA, 0.5 mM primer, 1.25 U Taq polymerase (MBI Fermentas), 0.2 mM each dNTP (Vivantis Technologies), 16 Taq buffer with KCl (pH 8) and 2 mM MgCl 2 .…”

Establishing Clonal Relationships between VIM-1-Like Metallo-β-Lactamase-Producing Pseudomonas aeruginosa Strains from Four European Countries by Multilocus Sequence Typing

“…Although several studies have explored the epidemiological relationships between isolates at a local level (8,9,18,31), no international comparisons of MBL-producing P. aeruginosa strains have been undertaken so far to elucidate questions of continental epidemiology. One limitation has been the lack of a proper methodology for comparing isolates which are temporally and geographically distant and handled by different laboratories.…”

“…In Italy, the first P. aeruginosa isolates producing the VIM-1 enzyme were found to belong to a single clonal lineage spreading in different hospitals since the late 1990s, which also included the VIM-1-producing index strain VR-143/97 (31). To date, bla VIM-1 alleles have not been detected in P. aeruginosa isolates from any other European country or elsewhere, although VIM-1 has been found in Escherichia coli and Klebsiella pneumoniae isolates from Greece and Spain (10,35,39).…”