Performance evaluation of Vitek 2 AST-N335 card for testing susceptibility of Acinetobacter baumannii to cefoperazone/sul-bactam
10.13602/j.cnki.jcls.2025.10.14
- VernacularTitle:Vitek 2 AST-N335药敏卡检测鲍曼不动杆菌头孢哌酮/舒巴坦药物敏感性的方法学评价
- Author:
Lingli GU
1
;
Hongmei SHEN
;
Linling HUANG
;
Meirong XU
;
Haiping LIU
;
Peilong LIU
;
Xiang LIU
;
Shirong DAI
Author Information
1. 南通市第二人民医院/南通市康复医院检验科,江苏南通 226002
- Publication Type:Journal Article
- Keywords:
Acinetobacter baumannii;
cefoperazone/sulbactam;
broth microdilution method;
antimicrobial susceptibility;
Vitek 2 AST-N335 susceptibility card;
methodological evaluation;
performance validation
- From:
Chinese Journal of Clinical Laboratory Science
2025;43(10):794-797
- CountryChina
- Language:Chinese
-
Abstract:
Objective To evaluate the reliability of Vitek 2 AST-N335 card for determining the susceptibility of Acinetobacter bauman-nii(AB)to cefoperazone/sulbactam.Methods A total of 318 non-repeated clinical isolates of AB collected in 2023 were tested for antimicrobial susceptibility to cefoperazone/sulbactam using broth microdilution(BMD),the AST-N335 card,and the Kirby-Bauer(K-B)disk diffusion method.Using BMD as the reference method,the reliability of AST-N335 card was assessed,and the accuracy of K-B disk diffusion method as the confirmatory test was validated.Results Compared with BMD,the susceptibility testing of 318 AB strains to cefoperazone/sulbactam using the AST-N335 card showed categorical agreement(CA)of 87.8％(279/318),very major er-ror(VME)of 6.0％(19/318),major error(ME)of 0％(0/318),and minor error(mE)of 1.9％(6/318),which fall outside of the acceptable error range.In contrast,the K-B method achieved CA of 99.4％(316/318),VME of 0％,ME of 0.3％(1/318),and mE of 0.3％(1/318),all within acceptable limits.Of these,the errors with AST-N335 card occurred within the minimum inhibitory concentration(MIC)range of 8-32 μg/mL.Using BMD as the reference method,further analysis was performed on the 171 AB strains with AST-N335 card MIC values of 8-32 μg/mL for cefoperazone/sulbactam.It was revealed that at MIC of 32 μg/mL,the CA was 0％;at MIC of 16 μg/mL,CA was 5.3％(1/19)and VME rate was 84.2％(16/19),both of which substantially exceeded accepta-ble error ranges.At MIC of 8 μg/mL,the CA was 94.9％(131/138)and VME was 2.2％(3/138),both approaching the acceptable ranges.Conclusion The results obtained with Vitek 2 AST-N335 card in determining for cefoperazone/sulbactam are unreliable when the MIC values fall within the range of 8-32 μg/mL,which leads to an underestimation of the resistance rate to cefoperazone/sulbac-tam.This issue requires urgent attention in both laboratories and clinical practice.The K-B disk diffusion method could serve as a sup-plementary verification approach in routine laboratories.
