ABSTRACT
Microbiological surveillance program is currently performed at our tertiary-care teaching Hospital. The temporal trend of microbial isolates from patients admitted during the last four calendar years (2004 to 2007), has been analyzed according to the main bacterial and fungal cultured organisms. The same pathogens isolated more than once from the same patient within one month, have been considered only once. On the whole, the main pathogen group remained that of Enterobacteriaceae (6,608 isolations out of 19,666: 33.6%, with Escherichia coli retrieved in 60-75% of cases), with no significant difference over time. Staphylococci (4,150 isolates), and enterococci (3,276 isolates), were the two largest groups after Enterobacteriaceae, but staphylococci significantly declined during the examined four-year period (p<.001), mainly due to a progressively reduced isolation of coagulase-negative staphylococci. On the other hand, a slight increase of enterococci occurred (p<.05). Based on the frequency of isolation, Gram-negative oxydasepositive organisms accounted for 2,109 episodes, followed by other aerobe Gram-positive organisms other than Staphylococci-Enterococci (613 isolates), and anaerobes (583 isolates): no significant temporal variations occurred over time for these last microbial groups. With regard to Gram-negative oxydase-negative microorganisms (567 isolates), non-betahemolytic streptococci (464 cases), and beta-hemolytic streptococci (260 isolates), a significant trend towards a reduction of frequency occurred from the year 2004 to 2007 (p<.05 to p<.001)