Journal List > Korean J Clin Microbiol > v.12(3) > 1038169

Park, Song, Kim, Kim, Kim, and Lee: Evaluation of the Vitek 2 AST-N055 Card for the Susceptibility Testing of Acinetobacter baumannii Isolates to Amikacin

Abstract

We collected 76 clinical isolates of Acinetobacter baumannii (amikacin MIC by Vitek 2 AST-N055 card: ≤2μg/mL, 11 isolates; 4μg/mL, 19 isolates; 8μg/ mL, 17 isolates; 16μg/mL, 27 isolates; and ≥64μg/ mL, 2 isolates) from a university hospital and evaluated the Vitek 2 AST-N055 card vs the broth microdilution as a reference method for testing susceptibility to amikacin. Vitek 2 AST-N055 card yielded very major errors in 15 isolates (19.7%) and minor errors in 26 isolates (34.2%). Of the 15 isolates shown very major errors, 14 had Vitek 2 MICs ranging from 8 to 16μg/mL. The results of our study suggest strongly that it is unreliable to test the amikacin susceptibility by Vitek 2 AST-N055 card of A. baumannii with the Vitek 2 MICs ranging from 8 to 16μg/mL. In those cases, another susceptibility test, such as broth microdilution (BMD), should be performed to confirm the results.

REFERENCES

1. Centers for Disease Control and Prevention. Acinetobacter baumannii infections among patients at military medical facilities treating injured U. S. service members, 2002-2004. MMWR Morb Mortal Wkly Rep. 2004; 53:1063–6.
2. Jeon BC, Jeong SH, Bae IK, Kwon SB, Lee K, Yong D, et al. Investigation of a nosocomial outbreak of imipenem-resistant Acinetobacter baumannii producing the OXA-23 β-lactamase in Korea. J Clin Microbiol. 2005; 43:2241–5.
3. Sunenshine RH, Wright MO, Maragakis LL, Harris AD, Song X, Hebden J, et al. Multidrug-resistant Acinetobacter infection mortality rate and length of hospitalization. Emerg Infect Dis. 2007; 13:97–103.
4. Wareham DW, Bean DC, Khanna P, Hennessy EM, Krahe D, Ely A, et al. Bloodstream infection due to Acinetobacter spp: epidemiology, risk factors and impact of multidrug resistance. Eur J Clin Microbiol Infect Dis. 2008; 27:607–12.
5. Clinical and Laboratory Standards Institute. Performance standards for antimicrobial susceptibility testing; eighteenth informational supplement. Document M100-S18. Wayne, PA; CLSI,. 2008.
6. Ling TK, Tom PC, Liu ZK, Cheng AF. Evaluation of VITEK 2 rapid identification and susceptibility testing system against gram-negative clinical isolates. J Clin Microbiol. 2001; 39:2964–6.
crossref
7. Hsieh WS, Sung LL, Tsai KC, Ho HT. Evaluation of the Vitek 2 cards for identification and antimicrobial susceptibility testing of non-glucose-fermenting Gram-negative bacilli. APMIS. 2009; 11:241–7.
crossref

Table 1.
Comparison of broth microdilution method and Vitek 2 AST-N055 card for amikacin susceptibility testing of 76 A. baumannii isolates
Category (MIC, μg/mL) No. of isolates
Broth microdilution Vitek 2
R (≥512) S (16) 1
R (128) R (≥64) 2
R (128) S (16) 1
R (64) S (16) 7
R (64) S (8) 5
R (64) S (4) 1
I (32) S (16) 12
I (32) S (8) 7
I (32) S (4) 7
S (16) S (16) 6
S (16) S (8) 3
S (16) S (4) 10
S (8) S (8) 2
S (8) S (4) 1
S (8) S (≤2) 5
S (4) S (≤2) 6
TOOLS
Similar articles