Analisi delle antibiotico-resistenze di Gram-negativi isolati da pazienti con infezioni del tratto urinario afferenti al Polo Oncologico e Dermatologico I.F.O.

Introduction. Urinary tract infections represent a worlwide problem due to their prevalence among nosocomial infections and to the increasing frequency of antibiotic resistance among the Gram-negative pathogens. Knowledge of the antimicrobial resistance patterns according to local epidemiology is essential for providing clinically appropriate therapy for urinary tract infection. In the present study we analysed the drug resistence pattern of Gram negative bacteria isolated from urine samples of patients with urinary tract infections at the Microbiological Laboratory of I.F.O., Rome. Materials and Methods. A total 3650 isolates have been collected during three years (2000-2003). Isolates were subcultured to Agar blood-Mac-Conckey and analysed in the Vitek 1 for identification and drug susceptibility. Results. As expected, Escherichia coli was found to be the main cause of urinary tract infection (73%). Proteus mirabilis, Klebsiella pneumoniae, and Pseudomonas aeruginosa, were less frequently isolated (9.,6%, 8.9% and 4.5%, respectively). The E. coli had the highest resistance rate to ampicillin (38%), followed by trimethoprim-sulphamethoxazole (22%) and ciprofloxacine (16%), while nitrofurantoin susceptibility of the E. coli isolates was still at acceptable levels (98%). The P. mirabilis isolates were found to be resistant to amoxycillin (35%), to trimethoprimsulphamethoxazole (34%).The P. aeruginosa isolates were found to be resistant to ciprofloxacina and imipenem (48% and 28% respectively). Conclusions.The increased drug resistance developed by bacteria consistently due to previous treatments with several antimicrobial drugs makes it essential the culture and susceptibility testing in genitourinary tract infection before instituting antimicrobial therapy. Empirical antimicrobial therapy should be avoided or reassessed by 48 to 72 hours after initation based on preterapy culture results.