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Comparison of Automated Broth Microdilution System (Vitek-2) and Agar Dilution Method in the Detection of Fosfomycin Susceptibility in <i>E. coli</i> and <i>K. pneumoniae</i> Isolates Causing Urinary Tract Infection
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RESEARCH ARTICLE
VOLUME: 10 ISSUE: 1
P: 26-26
January 2021

Comparison of Automated Broth Microdilution System (Vitek-2) and Agar Dilution Method in the Detection of Fosfomycin Susceptibility in E. coli and K. pneumoniae Isolates Causing Urinary Tract Infection

Mediterr J Infect Microb Antimicrob 2021;10(1):26-26
DOI: 10.4274/mjima.galenos.2021.2020.26
Ezgi AKPINAR 1
Nilgün KANSAK 1
Sebahat AKSARAY 2
1. University of Health Sciences Turkey, Haydarpaşa Numune Training and Research Hospital, Clinic of Medical Microbiology, İstanbul, Turkey
2. University of Health Sciences Turkey, Hamidiye Faculty of Medicine, Department of Medical Microbiology, İstanbul, Turkey
No information available.
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Summary

Introduction: Agar dilution is the reference method recommended by the European Committee on Antimicrobial Susceptibility Testing (EUCAST) for the detection of fosfomycin susceptibility in Gram-negative bacteria. However, this method is difficult to apply routinely in microbiology laboratories. For this reason, commercial automated systems have been developed to detect antibiotic susceptibility more easily and practically. In our study, we aimed to evaluate the utility of commercial automated broth microdilution system in routine studies to detect fosfomycin susceptibility by comparing it with the gold standard agar dilution method.
Materials and Methods: A total of 100 isolates of E. coli and K. pneumoniae isolated as urinary tract infection agents from urine samples, which were sent to Haydarpaşa Numune Training and Research Hospital, Medical Microbiology Laboratory between 01.06.2019 and 31.12.2019 were included in our study. Isolates were identified with matrix assisted lazer desorption/ionization-time of flight mass spectrometry (MALDI-TOF MS) (BioMerieux, France), and antibiotic susceptibility tests were performed with an automated broth microdilution system (Vitek-2, BioMerieux, France). Fosfomycin susceptibility was studied with the reference agar dilution method and the results were evaluated according to the EUCAST V.10.0 recommendations. In the evaluation made to compare the two methods, categorical agreement (CA), essential agreement (EA), very major error (VME), and major error (ME) values were calculated and the results were evaluated according to ISO 20776-1 criteria (CA and EA ≥90%; ME and VME <3%).
Results: When the data of the two methods were compared, CA and EA were found 100% for E. coli strains and 95.5% and 94.4% for K. pneumoniae strains, respectively. No ME or VME was detected for E. coli strains. While no VME was detected in K. pneumoniae strains, ME rate was 18%.
Conclusion: Based on the high CA rates in our study, it was thought that the Vitek-2 system would be suitable for routine laboratory use. However, due to the high ME rates in K. pneumoniae strains, it was concluded that the results should not be reported unless confirmed with the reference method, especially in resistant isolates.

Keywords:
Fosfomycin, agar dilution, automated broth microdilution method, Vitek-2, Gram-negative bacteria

References

1
Matthews PC, Barrett LK, Warren S, Stoesser N, Snelling M, Scarborough M, Jones N. Oral fosfomycin for treatment of urinary tract infection: a retrospective cohort study. BMC Infect Dis. 2016;16:556.
2
Uzun A, Gülen D, Tanriverdi Y, Demet Kaya A, Fosfomisin ve bazı antimikrobiyal ajanların üriner Escherichia coli izolatlarına in vitro etkinliğinin değerlendirilmesi. Klimik Derg. 2012;25:77-80.
3
Gupta K, Hooton TM, Naber KG, Wullt B, Colgan R, Miller LG, Moran GJ, Nicolle LE, Raz R, Schaeffer AJ, Soper DE, Infectious Diseases Society of America; European Society for Microbiology and Infectious Diseases. International clinical practice guidelines for the treatment of acute uncomplicated cystitis and pyelonephritis in women: a 2010 update by the Infectious Diseases Society of America and the European Society for microbiology and ınfectious diseases. Clin Infect Dis. 2011;52:e103-20.
4
Castañeda-García A, Blázquez J, Rodríguez-Rojas A. Molecular mechanisms and clinical impact of acquired and intrinsic fosfomycin resistance. Antibiotics (Basel). 2013;2:217-36.
5
Díez-Aguilar M, Cantón R. New microbiological aspects of fosfomycin. Rev Esp Quimioter. 2019;32:8-18.
6
The European Committee on Antimicrobial Susceptibility Testing – EUCAST MIC and zone diameter distributions and ECOFFs V.10.0 2020. Available from: http://www.eucast.org
7
Clinical and Laboratory Standards Institute (CLSI). Performance standards for antimicrobial susceptibility testing; 30th informational supplement. CLSI document M100-S76. Wayne, PA: CLSI: 2020. Available from: https://clsi.org/media/3481/m100ed30_sample.pdf
8
European Committee for Antimicrobial Susceptibility Testing (EUCAST) of the European Society of Clinical Microbiology and Infectious Diseases (ESCMID). EUCAST Definitive Document E.DEF 3.1, June 2000: Determination of minimum inhibitory concentrations (MICs) of antibacterial agents by agar dilution. Clin Microbiol Infect. 2000;6:509-15.
9
ISO 20776-1:2019 Susceptibility testing of infectious agents and evaluation of performance of antimicrobial susceptibility test devices - Part 1: Brothmicro-dilution reference method for testing the in vitro activity of antimicrobial agents against rapidly growing aerobic bacteria involved in infectious diseases. Available from: www.iso.org/standard
10
Demirci-Duarte S, Unalan-Altintop T, Eser OK, Cakar A, Altun B, Sancak B, Gur D. Prevalence of O25b-ST131 clone and fosfomycin resistance in urinary Escherichia coli isolates and their relation to CTX-M determinant. Diagn Microbiol Infect Dis. 2020;98:115098.
11
Nigiz Ş. Yatan hastaların idrar kültürlerinden izole edilen Klebsiella spp., Escherichia coli, Acinetobacter baumannii, Pseudomonas aeruginosa izolatlarının antibiyotik duyarlılıklarının in vitro yöntemlerle saptanması ve fosfomisine direnç mekanizmalarının araştırılması. Yüksek lisans tezi. Ankara: T.C. Hacettepe Üniversitesi Sağlık Bilimleri Enstitüsü;2020.
12
Van den Bijllaardt W, Schijffelen MJ, Bosboom RW, Cohen Stuart J, Diederen B, Kampinga G, Le TN, Overdevest I, Stals F, Voorn P, Waar K, Mouton JW, Muller AE, Susceptibility of ESBL Escherichia coli and Klebsiella pneumoniae to fosfomycin in the Netherlands and comparison of several testing methods including Etest, MIC test strip, Vitek2, Phoenix and disc diffusion. J Antimicrob Chemother. 2018;73:2380-7.
13
Camarlinghi G, Parisio EM, Antonelli A, Nardone M, Coppi M, Giani T, Mattei R, Rossolini GM, Discrepancies in fosfomycin susceptibility testing of KPC-producing Klebsiella pneumoniae with various commercial methods. Diagn Microbiol Infect Dis. 2019;93:74-6.
14
Karlowsky JA, Lagacé-Wiens PRS, Laing NM, Baxter MR, Adam HJ, Zhanel GG. Susceptibility of clinical isolates of Escherichia coli to fosfomycin as measured by four in vitro testing methods. J Clin Microbiol. 2020;58:e01306-20.
15
Aprile A, Scalia G, Stefani S, Mezzatesta ML. In vitro fosfomycin study on concordance of susceptibility testing methods against ESBL and carbapenem-resistant Enterobacteriaceae. J Global Antimicrob Resist. 2020;23:286-9.