Distribution and drug resistance of pathogens isolated from 4142 blood cultures

摘要

Objective:To investigate the distribution and drug resistance of pathogens isolated from 4142 blood cultures, and provide a scientific foundation for guiding clinical rational use of antimicrobial agents for bloodstream infections.Methods: Blood cultures obtained from 4142 inpatients and outpatients who were hospitalized from Jan 2015 to Dec 2016. The culture was detected by automatic BACT/ALERT 3D blood culture system of biomerieux. Bacteria isolated from positive blood cultures were further identified, and the drug susceptibility tests were conducted by VITEK-2 Compact automatic microbial analysis system and ATB Expression microbial analysis system. The drug susceptibility results were evaluated according to CLSI 2014 standard. Statistical analysis was performed by using WHONET 5.6 software. Results:A total of 396 unique strains were isolated from 4142 blood cultures, and the positive rate is 9.6%. Among the positive blood cultures, 194 (49.0%) strains were identified as Gram-positive, 185 (46.7%) strains were identified as Gram-negative, and 17(4.3%) strains were identified as fungi. The coagulase-negative Staphylococcus were the most frequently detectable (29.2%), followed by Escherichia coli (18.4%), Klebsiella pneumonia (7.3%), Staphylococcus aureus (5.1%), Acinetobacter baumannii(5.1%), and Enterococcus genera (5.1%). The incidences of methicillin resistant coagulase negative staphylococcus (MRCNS) and methicillin resistant staphylococcus aureus (MRSA) were 81.9% and 50.0% respectively. However, vancomycin resistant staphylococcus and enterococcus were not detected. The prevalence of extended spectrumβ lactamases (ESBLs) in E. coli and K. pneumoniae were 56.2% and 37.9%, respectively. All the E. coli strains were sensitive to amikacin, piperacillin/tazobactam, imipenem and meropenem, and the sensitive rate of K. pneumoniae strains to imipenem and meropenem were 93.1% and 89.7%, respectively.Conclusions MRCNS stains were the most frequently detected pathogens in blood cultures in the present study. The characteristic of drug resistance for the pathogens indicated that monitoring of imipenem and meropenem resistant K. pneumoniae should be underlined to prevent nosocomial outbreak. Fungi bloodstream infections of ward such as ICU and department of hemopathology should be enhanced monitored.