Pathogenic characteristics of Pseudomonas aeruginosa strains resistant to carbapenems associated with biofilm formation [Características patogénicas de cepas de Pseudomonas aeruginosa resistentes a carbapenémicos, asociadas con la formación de biopelículas]
Ochoa S.A.,Laboratorio Of Bacteriologia Intestinal |
Lopez-Montiel F.,Laboratorio Of Bacteriologia Intestinal |
Escalona G.,Laboratorio Of Bacteriologia Intestinal |
Cruz-Cordova A.,Laboratorio Of Bacteriologia Intestinal |
And 7 more authors.
Boletin Medico del Hospital Infantil de Mexico | Year: 2013
Background. In recent years, the worldwide emergence of multidrug-resistant strains of Pseudomonas aeruginosa has been observed. This opportunistic pathogen produces mechanisms of resistance to several antibiotics. The resistance to carbapenems in P. aeruginosa strains has been associated with bacterial biofilm formation, favored by the presence of exopolysaccharides (EPS) embedded in an extracellular matrix and to the production of type IV pili (T4P). We undertook this study to assess biofilm formation in clinical strains of P. aeruginosa resistant to carbapenems isolated at the Hospital Infantil de Mexico Federico Gomez (HIMFG) through quantification of total-reducing EPS and its association with the phenotypic expression of T4P. Methods. Antibiotic susceptibility tests were performed using the Kirby-Bauer method in 92 clinical isolates of P. aeruginosa; likewise, the minimum inhibitory concentration (MIC) was determined for imipenem (IMP) and meropenem (MEM) by the serial dilution method in agar plates with a Steers replicator. Production of metallo-β-lactamase (MBL) was determined by the disk diffusion method and synergism. Biofilm formation was performed in clinical isolates of P. aeruginosa resistant to carbapenems through the quantification of crystal violet, total sugar (anthrone), and reducing sugar (DNS), in addition to the phenotypic expression of T4P activity of twitching motility. The genetic diversity of strains forming biofilm and producing reducing sugars was evaluated by pulsed-field gel electrophoresis (PFGE).