Relatedness of Pseudomonas aeruginosa isolates producers of VIM2 from two central hospitals in Portugal

Abstract number: P1492

Reis T., Ribeiro G., Vital C., Alves A., Cardoso O.

Objective:Pseudomonas aeruginosa (PA) remains one of the most important pathogens in nosocomial setting. Understanding the pathogen distribution and relatedness is essential for determining the epidemiology of hospital infections and aiding in the design of rational pathogen control methods. In this work we proposed to characterise PA VIM-2 producers belonging to two central hospitals of Portugal by random amplification of polymorphic DNA (RAPD) to understand if isolates are inter or intra related between hospitals.

Methods: Of the 27 VIM-2 producing isolates, 15 were from Hospitais da Universidade de Coimbra (HUC) collected in first semester of 2008 and were from Neurotraumatology (WNT), Surgery III (WS), Hepatic Transplant Unit (HTU), Cardiology (WC), Medicine (WMI), Orthopedy (WO), Infectious (WIC), and Emergency (ER). Twelve were collected from Centro Hospitalar de Coimbra (CHC) during a year (2007–2008), and were from wards of Pneumology (WP), Neurosurgery (WN), Infectious (WI), Medicine (WM), Paediatric Hospital (PH), and Hospital of Pombal (HP). The samples were from different products, namely, urine, sputum, blood, and exudates. The minimal inhibitory concentration (MICs) of the VIM-2 strains was determined by E-test method. DNA was amplified using the primer 5'-AGCGGGCCAA-3'. We assigned a letter for each different RAPD profile.

Results: Among the 27 blaVIM-2 isolates the MICs revealed that aztreonam inhibited 81.5%, followed by piperacillin 66.7%, ceftazidime 25.9%, and meropenem 22.2%. RAPD typing generated 14 different patterns (A to O). Seven patterns were from HUC (A to G) and the most prevalent was pattern A that appeared to be disseminated in 3 wards namely WNT, WS and HTU (seven strains), and other patterns were represented by two or one strain. The patterns H to O belonged to CHC where H pattern was predominant (five strains) and appeared in different wards of PH, other profiles were constituted by one or two strains. Identical RAPD patterns between the two hospitals were not seen.

Conclusions: Fourteen genotypically different strains were identified, indicating that prevalence of carbapenemases-encoding genes was mainly due to a gene spread and in a lesser extent to clonal dissemination. The possibility of spreading of VIM-2 in Gram negative pathogens could emerge as a great problem in the clinical setting and underscores the need for systematic surveillance of these resistant determinants.