Epidemiological study of pathogens collected from blood for a period of a year (2008-2009)

Objectives. An epidemiological study, addressed to identify the pathogens isolated from blood, and their antibiotic susceptibility patterns, was conducted. Methods. 12 laboratories, homogeneously distributed in a Northern area of Italy, were required to collected all consecutive non-duplicated strains isolated from blood during February 2008 to February 2009 and sent them to the reference laboratory. Results. A total of 1092 microorganisms were collected, including 653 gram-positive, 385 gram-negative and 54 fungi. Escherichia coli 234, Staphylococcus epidermidis 205, S. aureus 142, S. hominis 87, Enterococcus faecalis 47, S. haemolyticus 33, Klebsiella pneumoniae 33, Pseudomonas aeruginosa 32, Candida albicans 28, Enterobacter cloacae 21 were the prevalent microrganisms found. Samples were collected mainly from medicine (255 strains), intensive care units (154), surgery (99), infectious diseases (93), paediatrics (62) and nephrology (62). Antibiotic resistance (in %) in staphylococci was 65.7 (methicillin), 33.5 (gentamicin), 61.8 (azithromycin), 59.6 (erythromycin), 45.2 (ciprofloxacin) 14.8 (chloramphenicol), 2.0 (teicoplanin), and 24.1 (trimethoprim-sulfamethoxazole) no vancomycin-resistant strain was found. Enterococci showed resistance to vancomycin (10.8), ampicillin (34.4), gentamycin (42.9), ciprofloxacin (42.2) teicoplanin (7.6), erythromycin (54.7) and chloramphenicol (17.5). Enterobacteriaceae exhibited resistance to ciprofloxacin(27.0), ampicillin (74.1), ceftazidime (15.8), cefoxitin (14.7), cefepime (13.3), ceftriaxone (15.0), both imipenem and amikacin (0.95), piperacillin-tazobactam (5.1) and trimethoprim-sulfamethoxazole (32.7). Non fermenting gram negative strains were found resistant to ciprofloxacin (27.3), ceftazidime (9.5), cefepime (14.6), ceftriaxone (81.6), both imipenem and amikacin (18.6), trimethoprim-sulfamethoxazole (65.2), and piperacillin-tazobactam (7.5). Conclusions.These data show a prevalent incidence of gram-positive (59.7 %) in comparison to gram-negative (35.3%) bacteria isolated from blood.A high percentage of methicillin-resistant staphylococci as well as ceftazidime-resistance among Enterobacteriaceae is also observed suggesting that this phenomenon requires periodically surveillance.