[Pseudomonas aeruginosa: antimicrobial resistance in clinical isolates. Castellón 2004-2008]

Retrospective study of antimicrobial susceptibility of 1.943 Pseudomonas aeruginosa clinical isolates to amikacin, tobramycin, gentamicin, ceftazidime, cefepime, meropenem, piperacillin-tazobactam and ciprofloxacin during a five year period. The percentage of resistance went from 2.07% to amikacin from 15.89% to ciprofloxacin. These percentages showed differences depending on the extra or intrahospital origin, departments and samples. Isolates from hospital patients were significantly more resistant than the ones from ambulatory patients (p < or = 0.001;tobramycin,13.74% vs 5.05%; gentamicin, 13.74% vs 8.26%; ceftazidime, 12.67% vs 4.24%; cefepime, 11.48% vs 7.07%; meropenem, 8.57% vs 2.06%), except for amikacin (1.98% vs 2.2%, p=0.74), piperacillin/ tazobactam (6.07% vs 4.55%, p=0.14) and ciprofloxacin (17.17% vs 13.97%, p=0.06).Critical care department and respiratory samples showed the highest resistance percentages while surgery department and invasive samples showed the lowest. Multidrug-resistance was found in 4.8% of the isolates. When comparing our data with those from our previous study (1992-2003), we observed a significant reduction in antibiotic resistance to amikacin (7.74% vs 2.07%, p<0.001), tobramycin (13.61% vs 10.26%, p<0.001), gentamicin (30.85% vs 14.73%, p<0,001), ceftazidime (14.63% vs 9,28%, p<0.001), cefepime (12.31% vs 9.71%, p=0.005), and meropenem (7.74% vs 2.07%, p=0.001); and there were no changes in resistance to piperacillin-tazobactam (4.26% vs 5.46%, p=0,06) and ciprofloxacin (16.02% vs 15.89%, p=0.89). In the last years, the susceptibility pattern of P. aeruginosa to antimicrobial agents has changed in our health district, and it is very different from the one described in national studies so it would be very important to monitor susceptibility of clinical isolates periodically.