Predominance of Gram-negative bacilli and increasing antimicrobial resistance in nosocomial bloodstream infections at a university hospital in southern Taiwan, 1996-2003

Abstract

Background and purpose: While nosocomial infections cause substantial morbidity and mortality, the availability of timely and accurate epidemiological information on nosocomial pathogens is essential to the appropriate selection of empirical therapy. This study analyzed nosocomial bloodstream infections (NBSIs) surveillance data to determine trends in the distribution of pathogens and antimicrobial susceptibilities of these pathogens.

Methods: During the period from 1996 to 2003 at National Cheng Kung University Hospital, patients with NBSIs were enrolled in the study, and the ranking of pathogens and status of antimicrobial resistance were determined.

Results: From 1996 to 2003, there were 4,038 episodes of NBSIs. The overall incidence was 1.79 episodes per 1,000 inpatient-days. Aerobic Gram-negative bacilli, Gram-positive cocci, fungi, and anaerobes were responsible for 51%, 37%, 10%, and 1.6% of NBSIs, respectively. The 5 leading pathogens were coagulase-negative staphylococci (16% of NBSIs), Staphylococcus aureus (13%), Candida spp. (10%), Acinetobacter baumannii (8%), and Escherichia coli (8%). Oxacillin resistance was found in 90% of coagulase-negative staphylococci and 75% of S. aureus isolates. In contrast to Enterococcus faecalis, in which only 1% of isolates were resistant to ampicillin, 78% of Enterococcus faecium isolates were resistant to ampicillin. The emerging antimicrobial-resistant Gram-negative pathogens included multidrug-resistant A. baumannii, cephalosporin- or fluoroquinolone-resistant E. coli, and extended-spectrum beta-lactamase producing Klebsiella pneumoniae and E. coli. Despite the annual increase in the use of fluconazole, Candida albicans (54%) remained the most common causative pathogen of nosocomial candidemia.

Conclusions: In summary, Gram-negative bacilli predominated among pathogens causing NBSIs and an upsurge in the threat of antimicrobial resistance in our hospital occurred during the 8-year period. Surveillance of the characteristics of NBSIs and antimicrobial resistance patterns, together with appropriate antibiotic and infection control measures, should be reinforced.