C Rodrigues

Publications (2)5.06 Total impact

• Article: Spread of an OmpK36-modified ST15 Klebsiella pneumoniae variant during an outbreak involving multiple carbapenem-resistant Enterobacteriaceae species and clones.

  A Novais, C Rodrigues, R Branquinho, P Antunes, F Grosso, L Boaventura, G Ribeiro, L Peixe
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  ABSTRACT: We aim to characterise multiple ertapenem-resistant (ERT-R, n = 15) Enterobacteriaceae isolates identified as presumptive carbapenemase producers in a Portuguese hospital in a short period of time (March-July 2010). Antibiotic susceptibility patterns, β-lactamases, genetic relatedness [pulsed-field gel electrophoresis (PFGE), multi-locus sequence typing (MLST)], plasmid content and major enterobacterial porins were investigated. Ertapenem resistance was associated with deficiencies in major porins and, in some cases, extended-spectrum β-lactamase (ESBL) or AmpC β-lactamase production among outbreak and non-outbreak clones. Most isolates (n = 8) corresponded to two ERT-R Klebsiella pneumoniae ST15 PFGE-types: (i) a sporadic variant (Kp-A-ERT, n = 1) presenting a premature stop codon in ompK36 and (ii) an epidemic variant (Kp-B-ERT, n = 7) exhibiting a new OmpK36 porin variant, which differed additionally in plasmid and antibiotic susceptibility profiles. ST14 (n = 1) and ST45 (n = 1) K. pneumoniae, ST131 (n = 1) and ST354 (n = 1) Escherichia coli, Enterobacter asburiae (n = 1), Enterobacter cloacae (n = 1) and Enterobacter aerogenes (n = 1) ERT-R clones were also sporadically detected. Porin changes in these isolates included non-sense mutations [ompK35, ompK36, ompF; minimum inhibitory concentration (MIC) = 4-32 mg/l], IS-mediated porin disruptions (ompK36, ompC; MIC = 12->32 mg/l) or alterations in the L3 loop (ompK36; MIC = 4-16 mg/l). We describe, for the first time in Portugal, the simultaneous emergence of multiple ERT-R Enterobacteriaceae species and clones in a short period of time. Moreover, our results support that a CTX-M-15-producing ST15 K. pneumoniae with an OmpK36-modified porin might successfully spread in the nosocomial setting.
  European Journal of Clinical Microbiology 06/2012; 31(11):3057-63. · 2.86 Impact Factor
• Article: Derivative spectrophotometry as a tool for the determination of drug partition coefficients in water/dimyristoyl-L-alpha-phosphatidylglycerol (DMPG) liposomes.

  C Rodrigues, P Gameiro, S Reis, J L Lima, B de Castro
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  ABSTRACT: The partition coefficients (K(p)) between lipid bilayers of dimyristoyl-L-alpha-phosphatidylglycerol (DMPG) unilamellar liposomes and water were determined using derivative spectrophotometry for chlordiazepoxide (benzodiazepine), isoniazid and rifampicin (tuberculostatic drugs) and dibucaine (local anaesthetic). A comparison of the K(p) values in water/DMPG with those in water/DMPC (dimyristoyl-L-alpha-phosphatidylcholine) revealed that for chlordiazepoxide and isoniazid, neutral drugs at physiological pH, the partition coefficients are similar in anionic (DMPG) and zwitterionic (DMPC) liposomes. However, for ionised drugs at physiological pH, the electrostatic interactions are different with DMPG and DMPC, with the cationic dibucaine having a stronger interaction with DMPG, and the anionic rifampicin having a much larger K(p) in zwitterionic DMPC. These results show that liposomes are a better model membrane than an isotropic two-phase solvent system, such as water-octanol, to predict drug-membrane partition coefficients, as they mimic better the hydrophobic part and the outer polar charged surface of the phospholipids of natural membranes.
  Biophysical Chemistry 01/2002; 94(1-2):97-106. · 2.20 Impact Factor