Roberto Melano

Publications (37) View all

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  Available from: Roberto Melano

  Article: Complete nucleotide sequence of blaKPC-4 and blaKPC-5 harboring IncN and IncX plasmids from Klebsiella pneumoniae strains isolated in New Jersey.

  Liang Chen, Kalyan D Chavda, Henry S Fraimow, José R Mediavilla, Roberto G Melano, Michael R Jacobs, Robert A Bonomo, Barry N Kreiswirth
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  ABSTRACT: Klebsiella pneumoniae carbapenemase (KPC) producing Enterobacteriaceae have emerged as major nosocomial pathogens. bla(KPC), commonly located on Tn4401, is found in Gram-negative bacterial strains, with the two most common variants, bla(KPC-2) and bla(KPC-3), identified in plasmids with diverse genetic backgrounds. In this study, we examined bla(KPC-4) and bla(KPC-5) bearing plasmids recovered from two K. pneumoniae strains, isolated from a single New Jersey hospital in 2005 and 2006, respectively. IncN plasmid pBK31551 is 84kb in length, and harbors bla(KPC-4), bla(TEM-1), qnrB2, aac (3)-Ib, aph(3')-I, qacF, qacEΔ1, sul and dfrA14, which confer resistance to ß-lactams, quinolones, aminoglycosides, quaternary ammonium compounds and co-trimoxazole. The conserved regions within pBK31551 are similar to that of other IncN plasmids. Surprisingly, analysis of the Tn4401 sequence revealed a large IS110 and Tn6901carrying element (8.3kb) inserted into the istA gene, encoding glyoxalase/bleomycin resistance, alcohol dehydrogenase and S-formylglutathione hydrolase. Plasmid pBK31567 is 47kb in length, and harbors bla(KPC-5), dfrA5, qacEΔ1 and sul1. pBK31567 belongs to a novel IncX subgroup (IncX5), and possesses a highly syntenic plasmid backbone like other IncX plasmids; however, sequence similarity at the nucleotide level is divergent. The bla(KPC-5) gene is carried on a Tn4401 element, and differs from the genetic environment of bla(KPC-5) described in Pseudomonas aeruginosa strain P28 from Puerto Rico. This study underscores the genetic diversity of multidrug resistant plasmids involved in the spread of bla(KPC) genes, and highlights the mobility and plasticity of Tn4401. Comparative genomic analysis provides new insights into the evolution and dissemination of KPC plasmids belonging to different incompatibility groups.
  Antimicrobial Agents and Chemotherapy 10/2012; · 4.84 Impact Factor
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  Article: Outbreak of Carbapenem-Resistant Enterobacteriaceae Containing blaNDM-1, Ontario, Canada.

  Sergio Borgia, Olga Lastovetska, David Richardson, Alireza Eshaghi, Jianhui Xiong, Catherine Chung, Mahin Baqi, Allison McGeer, Gloria Ricci, Rachael Sawicki, Rajni Pantelidis, Donald E Low, Samir N Patel, Roberto G Melano
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  ABSTRACT: Background. New Delhi metallo-ß-lactamase (NDM) has emerged worldwide in clinically relevant gram-negative bacteria. We report an outbreak of NDM-producing Klebsiella pneumoniae in patients with no prior travel history to endemic regions.Methods. Five NDM-1-producing K. pneumoniae colonizing and/or clinically infecting patients in a community tertiary hospital were detected between October and November 2011. NDM-1-producing Enterobacteriaceae (K. pneumoniae and Escherichia coli) were clinically and epidemiologically characterized, including susceptibility profiles, molecular typing, and molecular characterization of plasmids and resistant determinants.Results. Five patients were identified carrying NDM-1-producing K. pneumoniae, all of them epidemiologically linked with each other. K. pneumoniae were confirmed to belong to the same clone, exhibiting multidrug-resistant phenotypes. One patient was positive for NDM-1-producing E. coli in blood and E. coli and K. pneumoniae in rectal specimens, both containing the same bla(NDM) plasmid, suggesting horizontal transfer between species in the patient. No environmental sources of these strains were found. Detection of positive isolates directly from rectal specimens allowed the rapid identification and isolation of colonized patients.Conclusions. We report a NDM-1-producing K. pneumoniae outbreak in Ontario, Canada. Implementation of standard infection control practices, including active screening was able to contain the spread of this organism in the hospital setting. Of concern is the potential loss of a travel history to identify patients that are at high risk of being colonized or infected with this organism and the lack of an accurate, cost-effective test that can be implemented in the hospital setting to identify these multidrug-resistant organisms.
  Clinical Infectious Diseases 09/2012; · 9.15 Impact Factor
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  Article: MupB, a new high-level mupirocin resistance mechanism in Staphylococcus aureus.

  Christine Seah, David C Alexander, Lisa Louie, Andrew Simor, Donald E Low, Jean Longtin, Roberto G Melano
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  ABSTRACT: Mupirocin is a topical antibiotic used for the treatment of skin infections and the eradication of methicillin-resistant Staphylococcus aureus carriage. It inhibits bacterial protein synthesis by interfering with isoleucyl-tRNA synthetase activity. High-level mupirocin resistance (MIC of ≥ 512 μg/ml) is mediated by the expression of mupA (ileS2), which encodes an alternate isoleucyl-tRNA synthetase. In this study, we describe high-level mupirocin resistance mediated by a novel locus, mupB. The mupB gene (3,102 bp) shares 65.5% sequence identity with mupA but only 45.5% identity with ileS. The deduced MupB protein shares 58.1% identity (72.3% similarity) and 25.4% identity (41.8% similarity) with MupA and IleS, respectively. Despite this limited homology, MupB contains conserved motifs found in class I tRNA synthetases. Attempts to transfer high-level mupirocin resistance via conjugation or transformation (using plasmid extracts from an mupB-containing strain) were unsuccessful. However, by cloning the mupB gene into a shuttle vector, it was possible to transfer the resistance phenotype to susceptible S. aureus by electroporation, proving that mupB was responsible for the high-level mupirocin resistance. Further studies need to be done to determine the prevalence of mupB and to understand risk factors and outcomes associated with resistance mediated by this gene.
  Antimicrobial Agents and Chemotherapy 01/2012; 56(4):1916-20. · 4.84 Impact Factor
• Article: Cephalosporin resistance in Neisseria gonorrhoeae infections – Reply

  Vanessa G. Allen, Roberto G. Melano, Donald E. Low
  Journal of the American Medical Association 05/2013; 309(19):1989-1991.
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  Available from: Roberto Melano

  Article: Identification of sexual networks through molecular typing of quinolone-resistant Neisseria gonorrhoeae in Ontario, Canada.

  Kaede V Ota, Lai-King Ng, Roberto G Melano, Irene E Martin, Elizabeth M Brown, Susan E Richardson, David N Fisman, Donald E Low, Frances B Jamieson
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  ABSTRACT: Neisseria gonorrhoeae multi-antigen sequence typing technique demonstrated multiple sexual transmission networks in Ontario, Canada. Isolates with novel sequences had higher odds of originating in Toronto but had no association with heightened population-level quinolone exposure. Neisseria gonorrhoeae multi-antigen sequence typing technique can be a useful tool for investigation of multidrug-resistant N. gonorrhoeae emergence in North America.
  Sexually transmitted diseases 09/2011; 38(9):811-4. · 2.58 Impact Factor