Epidemiological study on distribution and antibiotic susceptibility patterns of Enterobacteriaceae and non-fermenting bacteria, isolated in Liguria and in a neighbouring area

Introduction. An epidemiological study addressed to identify gram-negative bacteria, isolated from laboratories in a Northern area of Italy, and their antibiotic resistance patterns was conducted. Methods. Twelve laboratories distributed on Ligurian territory or neighbouring areacollected all consecutive gram-negative isolates belonging to the Enterobacteriaceae family and non-fermenter group for 2 months and sent them to a reference laboratory. Results. A total of 1880 pathogens were collected, including 899 and 981 strains isolated from nosocomial- and community-acquired infections, respectively. Escherichia coli (63.3% of total) was the most frequently isolated pathogen followed by Pseudomonas aeruginosa (9.6%), Proteus mirabilis (8.9%) and Klebsiella pneumoniae (5.4%). Nosocomial samples were collected mainly from patients in general medicine wards (19.9%) and healthcare settings (14.1%). Urine was the most common clinical sample (79.9% of the total). Other samples were sputum and bronchoaspirates (8%), skin wounds including those from decubitus (5.3%) and blood (4.1%). E. coli and P. mirabilis were collected mainly from urinary tract infection while P. aeruginosa appears more involved in respiratory or other infections. Considering the resistance to representative classes of antibiotics, it was higher (%) for piperacillin-tazobactam in P. mirabilis (30.3), for ceftazidime in Enterobacter aerogenes (40.8) and in Providencia stuartii (40), for imipenem and amikacin in P. aeruginosa (16.2 and 13.7 respectively), for ciprofloxacin in P. stuartii (66.6) and in P. mirabilis (44.7) than in others bacteria. Conclusions. The increasing age of the population in general medical wards and healthcare settings is associated with urinary tract and bedsore infections. E. coli confirms its epidemiologic and pathogenic role, but P. mirabilis and P. aeruginosa are emerging as alternativechallenges.