Detecting In-Vitro Colistin Resistance- A Comparative Study Between Broth Microdilution Versus Vitek-2 For Colistin Susceptibility Testing
Keywords:
Colistin, susceptibility, Broth microdilution, Vitek-2
Abstract
Background: Susceptibility testing for polymyxins is a great challenge for a Clinical Microbiology laboratory. There are several methodological issues associated with MIC (Minimum Inhibitory Concentration) determination of colistin. Methods: In our study, we have compared the results of colistin susceptibility testing by Automated system (Vitek-2, Biomerieux, France) with the reference Broth Microdilution method (BMD) to identify the type of discrepancies by Vitek-2 method and thus develop a practical and accurate approach for colistin susceptibility testing in a Clinical Microbiology laboratory. A total of 730 strains of Gram negative bacteria [Escherichia coli (325), Klebsiella sp.(346), Acinetobacter baumanii complex (37) and Pseudomonas aeruginosa (22)] from 485 patents were tested simultaneously by BMD and Vitek-2 method for colistin susceptibility testing. Results: The Essential agreement (EA), Categorical agreement (CA), Very major error (VME) and Major error (ME) rates for Klebsiella sp. were 87.3%, 89.3%, 8% and 2.3% respectively, for Escherichia coli were 88.3%, 89.5%, 9.2% and 1.2% respectively, for Acinetobacter baumannii complex were 89.1%, 91.8%, 8.1% and 0% respectively, for Pseudomonas aeruginosa were 68.1%, 72.7%, 0% and 27.2% respectively. Conclusions: Colistin susceptibility testing by Vitek-2 method is an easily adoptable method and the results of Vitek-2 with reference to BMD are acceptable to a great extent in Klebsiella sp., Escherichia coli and Acinetobacter baumanii complex. So, we believe that Vitek-2 method may be used for colistin susceptibility testing in low risk patients. However, BMD should be used in high risk immunosupressed and immunocompromised patients who are admitted in critical care units. For Pseudomonas aeruginosa, BMD should be routinely used.References
1. Falagas ME, Kasiakou SK. Colistin: the revival of polymyxins for the management of multidrug-resistant Gram-negative bacterial infections. Clin Infect Dis 2005;40:1333–1341.
2. Poirel L, Jayol A, Nordmann P. Polymyxins: antibacterial activity, susceptibility testing, and resistance mechanisms encoded by plasmids or chromosomes. Clin Microbiol Rev 2017;30:557–596.
3. http://www.eucast.org/fileadmin/src/media /PDFs/EUCAST_files/General_documents/ Recommendations_for_MIC_determination_of_colistin_March_2016.pdf).
4. Hindler JA, Humphries RM. 2013. Colistin MIC variability by method for contemporary clinical isolates of multidrug-resistant Gram-negative bacilli. J Clin Microbiol 51:1678 –1684.
5. Lo-Ten-Foe JR, de Smet AM, Diederen BM, Kluytmans JA, van Keulen PH. Comparative evaluation of the VITEK 2, disk diffusion, E test, broth microdilution, and agar dilution susceptibility testing methods for colistin in clinical isolates, including heteroresistant Enterobacter cloacae and Acinetobacter baumannii strains. Antimicrob Agents Chemother 2007;51:3726 –3730.
6. Tan TY, Ng SY. Comparison of Etest, Vitek and agar dilution for susceptibility testing of colistin. Clin Microbiol Infect 2007;13:541–544.
7. CLSI. Performance Standards for Antimicrobial Susceptibility Testing. 28th ed. CLSI supplement M100. Wayne,PA: Clinical and Laboratory Standards Institute; 2018.
8. CLSI. Methods for Dilution Antimicrobial Susceptibility Tests for Bacteria that grow aerobically. 11th ed. CLSI standard M07. Wayne,PA: Clinical and Laboratory Standards Institute;2018.
9. Patel JB, Sharp S, Novak-Weekley S. Verification of Antimicrobial Susceptibility methods: a Practical approach. Clinical Microbiology Newsletter 2013;35(13):103-9.
10. International Organization for Standardization. 2007. ISO 20776-2: 2007(E). Clinical laboratory testing and in vitro diagnostic test systems. Susceptibility testing of infectious agents and evaluation of performance of antimicrobial susceptibility test devices. Part 2: evaluation of performance of antimicrobial susceptibility test devices. International Organization for Standardization, Geneva, Switzerland.
11. Vourli S, Dafopoulou K, Vrioni G, Tsakris A, Pournaras S. Evaluation of two automated systems for colistin susceptibility testing of carbapenem-resistant Acinetobacter baumannii clinical isolates.J Antimicrob Chemother. 2017;72(9):2528-2530
12. Bakthavatchalam YD, Veeraraghavan B, Shankar A, Thukaram B, Krishnan DN. Evaluation of colistin and polymyxin B susceptibility testing methods in Klebsiella pneumoniae and Acinetobacter baumannii. J Infect Dev Ctries 2018;12(6):504-507
13. Dafopoulou K, Zarkotou O, Dimitroulia E, Hadjichristodoulou C, Gennimata V, Pournaras S, Tsakrisa A. Comparative Evaluation of Colistin Susceptibility Testing Methods among Carbapenem-Nonsusceptible Klebsiella pneumoniae and Acinetobacter baumannii clinical isolates. Antimicrobial agents and Chemotherapy 2015;59:4625-4630.
14. Matuschek E, Åhman J, Webster C, Kahlmeter G. Antimicrobial susceptibility testing of colistin – evaluation of seven commercial MIC products against standard broth microdilution for Escherichia coli, Klebsiella pneumoniae, Pseudomonas aeruginosa, and Acinetobacter spp. Clinical Microbiology and Infection 2018;24:865-870.
2. Poirel L, Jayol A, Nordmann P. Polymyxins: antibacterial activity, susceptibility testing, and resistance mechanisms encoded by plasmids or chromosomes. Clin Microbiol Rev 2017;30:557–596.
3. http://www.eucast.org/fileadmin/src/media /PDFs/EUCAST_files/General_documents/ Recommendations_for_MIC_determination_of_colistin_March_2016.pdf).
4. Hindler JA, Humphries RM. 2013. Colistin MIC variability by method for contemporary clinical isolates of multidrug-resistant Gram-negative bacilli. J Clin Microbiol 51:1678 –1684.
5. Lo-Ten-Foe JR, de Smet AM, Diederen BM, Kluytmans JA, van Keulen PH. Comparative evaluation of the VITEK 2, disk diffusion, E test, broth microdilution, and agar dilution susceptibility testing methods for colistin in clinical isolates, including heteroresistant Enterobacter cloacae and Acinetobacter baumannii strains. Antimicrob Agents Chemother 2007;51:3726 –3730.
6. Tan TY, Ng SY. Comparison of Etest, Vitek and agar dilution for susceptibility testing of colistin. Clin Microbiol Infect 2007;13:541–544.
7. CLSI. Performance Standards for Antimicrobial Susceptibility Testing. 28th ed. CLSI supplement M100. Wayne,PA: Clinical and Laboratory Standards Institute; 2018.
8. CLSI. Methods for Dilution Antimicrobial Susceptibility Tests for Bacteria that grow aerobically. 11th ed. CLSI standard M07. Wayne,PA: Clinical and Laboratory Standards Institute;2018.
9. Patel JB, Sharp S, Novak-Weekley S. Verification of Antimicrobial Susceptibility methods: a Practical approach. Clinical Microbiology Newsletter 2013;35(13):103-9.
10. International Organization for Standardization. 2007. ISO 20776-2: 2007(E). Clinical laboratory testing and in vitro diagnostic test systems. Susceptibility testing of infectious agents and evaluation of performance of antimicrobial susceptibility test devices. Part 2: evaluation of performance of antimicrobial susceptibility test devices. International Organization for Standardization, Geneva, Switzerland.
11. Vourli S, Dafopoulou K, Vrioni G, Tsakris A, Pournaras S. Evaluation of two automated systems for colistin susceptibility testing of carbapenem-resistant Acinetobacter baumannii clinical isolates.J Antimicrob Chemother. 2017;72(9):2528-2530
12. Bakthavatchalam YD, Veeraraghavan B, Shankar A, Thukaram B, Krishnan DN. Evaluation of colistin and polymyxin B susceptibility testing methods in Klebsiella pneumoniae and Acinetobacter baumannii. J Infect Dev Ctries 2018;12(6):504-507
13. Dafopoulou K, Zarkotou O, Dimitroulia E, Hadjichristodoulou C, Gennimata V, Pournaras S, Tsakrisa A. Comparative Evaluation of Colistin Susceptibility Testing Methods among Carbapenem-Nonsusceptible Klebsiella pneumoniae and Acinetobacter baumannii clinical isolates. Antimicrobial agents and Chemotherapy 2015;59:4625-4630.
14. Matuschek E, Åhman J, Webster C, Kahlmeter G. Antimicrobial susceptibility testing of colistin – evaluation of seven commercial MIC products against standard broth microdilution for Escherichia coli, Klebsiella pneumoniae, Pseudomonas aeruginosa, and Acinetobacter spp. Clinical Microbiology and Infection 2018;24:865-870.
Published
2020-07-28
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