Epidemiology of bacteremia episodes in a single center: increase in Gram-negative isolates, antibiotics resistance, and patient age

Increased resistance among isolates causing bacteremia constitutes a major challenge to medical practitioners and institutions. Variability between institutes is substantial, and requires the individual analysis of local trends. An eight-year (1997-2004) surveillance study of episodes of bacteremia was conducted in an 850-bed university hospital in central Israel. Trends of incidence, resistance, age, and mortality were analyzed. We studied 6,096 patient-unique episodes of bacteremia, of which, 2,722 (45.3%) were nosocomial and 523 (9.2%) involved children less than 18 years of age. The overall incidence of bacteremia episodes has increased over the study years by 39% and the patient mean age by 7.5 years. Gram-negative organisms accounted for 72% of hospital-acquired cases and 69% of community-acquired cases. There was a substantial increase in the incidence of nosocomial episodes, predominantly due to Gram-negative isolates, mainly Acinetobacter baumannii, Klebsiella pneumoniae, and Escherichia coli. Increased resistance to broad-spectrum antibiotics was noted among Gram-negative organisms, including quinolones (in K. pneumoniae), imipenem (A. baumannii and P. aeruginosa), piperacillin-tazobactam (K. pneumoniae), and amikacin (A. baumannii and P. aeruginosa). Increased resistance to oxacillin among coagulase-negative staphylococci was also noted. The all-cause mortality rates showed a significant rise. The patient age, intensive care unit (ICU) stay, and hospital acquisition were independently associated with mortality. We describe an increase in the incidence and resistance of Gram-negative organisms causing bacteremia and concomitant ageing of the patients with bacteremia. Similar patterns have been reported from other localities, and are of real concern.