Clinical evaluation of direct drug sensitivity test for blood culture positive broths / 中华检验医学杂志

ABSTRACT

Objective:To evaluate the clinical performance of direct antimicrobial susceptibility test in blood culture-positive broth, and to provide a basis for optimizing the antibiotic use strategy in clinical bloodstream infection.Methods:A retrospective analysis was conducted on 780 blood culture-positive samples collected in Peking University People′s Hospital from May 2017 to December 2021. The direct antimicrobial susceptibility test was performed by disk diffusion method on blood culture-positive broth. The antimicrobial susceptibility breakpoints were in accordance with Clinical and Laboratory Standards Institute (CLSI) M100 S32 edition document.Results:In this study, a total of 331 strains of Gram-negative bacteria (139 strains of Escherichia coli, 79 strains of Klebsiella pneumoniae, 35 strains of Pseudomonas aeruginosa, 21 strains of Acinetobacter baumannii) and 396 strains of Gram-positive cocci (25 strains of Staphylococcus aureus, 316 strains of coagulase-negative staphylococci, 47 strains of Enterococcussp.) were collected, after excluding 53 cases with two or more isolates. Compared with the routine antimicrobial susceptibility test (AST), the rates of category agreement (CA), major error (ME), and very major error (VME) of Gram-negative bacteria were 86.0% (1368/1 591), 8.7% (139/1 591), and 0.5% (8/1 591), respectively. On the other hand, the CA%, ME%, and VME% of Gram-positive cocci were 89.2% (960/1 076), 7.5% (81/1 076), and 1% (11/1 076), respectively. Regarding the individual antimicrobial agents, the CA% of Escherichia coli was 16/17 for imipenem, 90.1% (109/121) for meropenem, and 70.8% (85/120) for cefepime. For Klebsiella pneumoniae, the CA% of was 10/13 for imipenem, 80.9% (55/68) for meropenem, and 80.3% (53/66) for cefepime. The CA% of meropenem in Pseudomonas aeruginosa and Acinetobacter baumannii were 96.0% (24/25) and 16/16. The CA% of linezolid and cefoxitin in Staphylococcus aureus were 100% (25/25) and 100% (24/24), respectively. The CA% of linezolid, cefoxitin and gentamicin in coagulase-negative staphylococci were 98.9% (269/272), 94.5% (277/293) and 71.6% (194/271) respectively. Finally, for Enterococcus sp., the CA% of vancomycin and ampicillin were 91.5% (43/47) and 94.7% (36/38), respectively. Conclusion:Compared with the conventional AST, the blood culture-positive broth direct AST exhibited high category agreement and low error rates for both Gram-negative bacteria and Gram-positive cocci, which can serve a rapid alternative for AST in cases of clinical bloodstream infection.