ABSTRACT
Objective To collect the laboratory parameters and clinical parameters of blood culture positive samples,and analyze the composition and laboratory characteristics of real pathogens by combining with clinical follow-up and anti-infectious treatment outcomes.Methods We conducted a prospective study to isolate the 483 strains of pathogens from 4313 cases of blood samples for clinical examination between March 2013 and March 2015.The results of laboratory and clinical infections were collected for each positive culture and were followed up for clinical follow-up to understand the responsible doctors' experience-based judgment and targeted clinical treatment of antibiotics.After comprehensive analysis we determined the real pathogens and contaminants.Results Of the 483 positive cultures,331 were finally determined as pathogenic ones,accounting for 68.5% of the number of positive isolates; 97 were contaminated bacteria (20.1%); and 55 strains with uncertain pathogenic nature (11.4%).Escherichia coli accounted for the highest proportion (41.2%)of pathogenic bacteria.Coagulase-negative staphylococci took up the highest proportion (75.3%)of the contaminated bacteria.As many as 253 strains (52.4%)were detected from the aerobic or anaerobic bottles.The detection rate of Escherichia coli in anaerobic bottles (23.9%)was higher than that in aerobic bottles (13.8%)(P <0.05).Of 97 strains of positive isolates,only one bottle was reported positive for 90 strains,accounting for (92.8%),and more than two bottles of 7 positive strains,accounting for (7.2%)(P <0.05).34 positive in 24 h (35.1%),77 positive in 48 h (79.4%),the positivebacteria ratio within 48 h (79.4%)was higher than that of bacteria contamination ratio within 24 h (χ2 =38.935, P =0.000),with a significant difference.Conclusion Establishment of contaminated bacteria in blood culture cannot rely solely on laboratory or clinical parameters.It should be combined with the experience of clinicians to determine the clinical response to comprehensive judgments.For the laboratory to determine the presence of contamination,the number of positive bottles and the amount of sun are still two factors of important value.Paying attention to inspection of anaerobic bottles is more conducive to the detection of Escherichia coli.
ABSTRACT
Objective To collect the laboratory parameters and clinical parameters of blood culture positive samples,and analyze the composition and laboratory characteristics of real pathogens by combining with clinical follow-up and anti-infectious treatment outcomes.Methods We conducted a prospective study to isolate the 483 strains of pathogens from 4313 cases of blood samples for clinical examination between March 2013 and March 2015.The results of laboratory and clinical infections were collected for each positive culture and were followed up for clinical follow-up to understand the responsible doctors' experience-based judgment and targeted clinical treatment of antibiotics.After comprehensive analysis we determined the real pathogens and contaminants.Results Of the 483 positive cultures,331 were finally determined as pathogenic ones,accounting for 68.5% of the number of positive isolates; 97 were contaminated bacteria (20.1%); and 55 strains with uncertain pathogenic nature (11.4%).Escherichia coli accounted for the highest proportion (41.2%)of pathogenic bacteria.Coagulase-negative staphylococci took up the highest proportion (75.3%)of the contaminated bacteria.As many as 253 strains (52.4%)were detected from the aerobic or anaerobic bottles.The detection rate of Escherichia coli in anaerobic bottles (23.9%)was higher than that in aerobic bottles (13.8%)(P <0.05).Of 97 strains of positive isolates,only one bottle was reported positive for 90 strains,accounting for (92.8%),and more than two bottles of 7 positive strains,accounting for (7.2%)(P <0.05).34 positive in 24 h (35.1%),77 positive in 48 h (79.4%),the positivebacteria ratio within 48 h (79.4%)was higher than that of bacteria contamination ratio within 24 h (χ2 =38.935, P =0.000),with a significant difference.Conclusion Establishment of contaminated bacteria in blood culture cannot rely solely on laboratory or clinical parameters.It should be combined with the experience of clinicians to determine the clinical response to comprehensive judgments.For the laboratory to determine the presence of contamination,the number of positive bottles and the amount of sun are still two factors of important value.Paying attention to inspection of anaerobic bottles is more conducive to the detection of Escherichia coli.
ABSTRACT
Objective To analyze the significance of time to positivity(TTP)of blood culture in differentiating bloodstream infection(BSI)from contamination during blood withdrawal.Methods Clinical data and TTP of blood culture in patients hospitalized in different departments from November 2013 to November 2014 were compared retrospectively,role of TTP in differential diagnosis of BSI was evaluated.Results Of 2 605 blood culture specimens,137 were positive for blood culture,78 (56.93%)of which were pathogenic bacteria and 59(43.07%) were contaminated bacteria,coagulase negative staphylococcus had the highest contamination rate(75.76%),while Escherichia coli had the lowest contamination rate(12.50%).TTP of pathogenic bacteria was shorter than that of contaminated bacteria ([13.86 ±8.19]h vs [40.72 ±20.96]h,P <0.05 ).Of pathogenic bacteria,Enterococcus had the earliest TTP ([10.20±8.00]h),followed by Escherichia coli ([11 .12 ±3.91 ]h),Staphylococcus aureus ([12.22±5.08]h),Klebsiella pneumoniae ([14.72±10.45]h),the other gram-negative bacteria([16.11 ±12.97] h),and coagulase negative staphylococci([16.42±5.74]h),fungi had the latest TTP ([29.04±3.67]h ).TTP of gram-negative bacteria was ≤16.59 h,sensitivity and specificity of BSI were 84.09% and 100.00% respectively;TTP of gram-positive bacteria was ≤20.96 h,sensitivity and specificity of BSI were 96.77% and 94.44% respec-tively.Conclusion Combination of TTP of blood culture and other clinical indications can provide reference for early differentiating isolated pathogenic bacteria from contaminated bacteria.