Clinical distribution and drug resistance of pathogens causing bloodstream infections in a single center from 2006 to 2009

Abstract

Objective To investigate the clinical distribution and drug resistance of pathogens causing bloodstream infection (BSI) , and to guide reasonable use of antibiotics in clinical practices.Methods A BacT/ALERT 3D fully automatic microbe detection system was used for blood culture, and VITEK- 2 fully automatic system for pathogen identification and drug sensitivity test. The results were collected and analyzed using Whonet 5.4 software. Medical records were retrieved for clinical data of the patients during hospital stay. Results From 10 462 blood culture specimens collected in Sun Yat-sen Memorial Hospital of Sun Yat-sen University from 2006 to 2009, 830 strains of pathogens (overall positive rate: 7.9％ ) were identified, including 442 strains (53.3％) of Gram - negative bacilli (GNB) with predominating E.coli [149/442, 33.7％], 275 strains (33.2％) of Gram-positive cocci with predominating coagulase-negative staphylococci (CoNS) [122/275, 44.4％], and 113 strains (13.6％) of fungi with predominating Caadida tropicalis [28/113, 24.8％]. The most common pathogens that caused BSI was E.coli (18.0％), followed by CoNS (14.7％) and Klebsiella pneumoniae (8.2％). ESBLs production was found in 67.5％ and 49.1％ of E.coli and Klebsiella pneumoniae strains respectively. Carbapenems and amikacin (AMK) showed favorable antibacterial activity against enterbacteriaceae, while levofloxacin (LVFX)showed favorable, in vitro antibacterial activity against common non-fermenters. The detection rate for MRSA and MRCoNS was 53.2％ and 88.5％ respectively. Vancomycin-resistance Gram positive cocci were not detected.ICU, departments of pediatrics and hematology were major sources of clinical distribution (25.5％, 22.2％and 12.4％ ). The underlying diseases in patients with bloodstream infections mainly included malignant tumor (26.8％) and hematopathy (20.6％). Conclusion In our hospital, the most common BSI-causing pathogens are E.coli, followed by CoNS and Klebsiella pneumonia. Vancomycin, teicoplanin, and quinupristin/dalfopristin show favorable antibacterial activity against Gram-positive cocci, as do carbapenems and LVFX against Gram-negative bacilli. Subjects with underlying malignant tumor or hematopathy are more likely to develop bloodstream infections. Key words: Bacterial infections and mycoses; Cell, cultured; Bloodstream infection; Epidemiological characteristic; Antimicrobial susceptibility test