Showing papers by "Maria Virginia Villegas published in 2008"
TL;DR: Genetic structures surrounding the carbapenem-hydrolyzing Ambler class A blaKPC gene were characterized in several KPC-positive Klebsiella pneumoniae and Pseudomonas aeruginosa strains isolated from the United States, Colombia, and Greece.
Abstract: Genetic structures surrounding the carbapenem-hydrolyzing Ambler class A bla KPC gene were characterized in several KPC-positive Klebsiella pneumoniae and Pseudomonas aeruginosa strains isolated from the United States, Colombia, and Greece. The bla KPC genes were associated in all cases with transposon-related structures. In the K. pneumoniae YC isolate from the United States, the β-lactamase bla KPC-2 gene was located on a novel Tn 3 -based transposon, Tn 4401 . Tn 4401 was 10 kb in size, was delimited by two 39-bp imperfect inverted repeat sequences, and harbored, in addition to the β-lactamase bla KPC-2 gene, a transposase gene, a resolvase gene, and two novel insertion sequences, IS Kpn6 and IS Kpn7 . Tn 4401 has been identified in all isolates. However, two isoforms of this transposon were found: Tn 4401 a was found in K. pneumoniae YC and K. pneumoniae GR from the United States and Greece, respectively, and differed by a 100-bp deletion, located just upstream of the bla KPC-2 gene, compared to the sequence of Tn 4401 b, which was found in the Colombian isolates. In all isolates tested, Tn 4401 was flanked by a 5-bp target site duplication, the signature of a recent transposition event, and was inserted in different open reading frames located on plasmids that varied in size and nature. Tn 4401 is likely at the origin of carbapenem-hydrolyzing β-lactamase KPC mobilization to plasmids and its further insertion into various-sized plasmids identified in nonclonally related K. pneumoniae and P. aeruginosa isolates.
468 citations
TL;DR: In South American countries, the class A extended-spectrum b-lactamases (ESBLs) so far recognised belong to the CTX-M, Pseudomonas Extended Resistance (PER), SHV, SHV and TEM families.
118 citations
TL;DR: The newly approved doripenem should prove to be a valuable addition to the currently available carbapenems: imipenems, meropenem and ertapenem, which should limit the emergence of resistance and prolong the utility of these agents.
87 citations
Journal Article•
TL;DR: The most frequently used mechanisms of resistance by Gram negative bacteria are described, emphasizing on Beta-lactam antibiotics.
48 citations
01 Jan 2008
TL;DR: The most frequently used mechanisms of resistance by Gram negative bacteria are described, emphasizing on beta-lactam antibiotics.
Abstract: Infections caused by Gram negative bacteria are highly prevalent in hospitalized patients, especially in intensive care units. Multidrug resistant strains represent a therapeutic challenge, leaving very few possibilities for the treatment of such infections. The mechanisms that this bacteria use to defend themselves from antibiotics are constantly evolving. This review describes the most frequently used mechanisms of resistance by these germs, emphasizing on beta-lactam antibiotics.
6 citations