[Carbapenems resistance in Pseudomonas aeruginosa during a 10-year period at Rawson Hospital].

BACKGROUNDS: Pae is a non-fermenting, Gram-negative bacillus that is associated with nosocomial infections and can easily be transmitted through the hands of health staff from patient to patient. Pae has a wide variety of natural resistance mechanisms and a great capacity to acquire new resistance mechanisms or to increase the expression of their natural resistance. Carbapenems resistance may be offered by impermeability mechanisms, increase in the efflux or enzymatic pump (production of carbapenemases). PURPOSE: To determine prevailing carbapenems resistance mechanisms in Pae and their evolution. MATERIALS AND METHODS: 372 Pae strains were collected during a ten-year period. The strains were identified through biochemical tests and performed a sensitivity test through diffusion and microbiological method. RESULTS: carbapenems resistance mechanisms for efflux in the year 2000 were , 50%; 2001 16.6%, 2002 6.3%, 2003 23.9%, 2004 18%, 2005 8.8%, 2006 17.8%, 2007 31.8%, 2008 2.5%, 2009 5.2%. As regards impermeability: 2000 33%, 2001 21.4%, 2002 8.5%, 2003 30.4%, 2004 14.7%, 2005 28.8%, 2006 23.5%, 2007 13.6%, 2008 2.5%, 2009 5.2%. The microbiological test was negative for all studied strains. CONCLUSION: carbapenems resistance during this period was offered by impermeability and an increase in the expression of the efflux mechanism, not by enzymatic mechanism in our hospital. This is a very important issue from an epidemiological point of view because of the rapid horizontal transmission of the strains with this resistance mechanism.