Direct Urine Resistance Detection Using VITEK 2

Abstract

Urinary tract infections (UTIs) are the most common infectious diseases in both communities and hospitals. With non-anatomical or functional abnormalities, UTIs are usually self-limiting, though women suffer more reinfections throughout their lives. Certainly, antibiotic treatment leads to a more rapid resolution of symptoms, but also it selects resistant uropathogens and adversely affects the gut and vaginal microbiota. As uropathogens are increasingly becoming resistant to currently available antibiotics, it could be time to explore alternative strategies for managing UTIs. Rapid identification and antimicrobial susceptibility testing (AST) allow fast and precise treatment. The objective of this study was to shorten the time of diagnosis of UTIs by combining pathogen screening through flow cytometry, microbial identification by matrix-assisted laser desorption ionisation time-of-flight mass spectrometry (MALDI-TOF MS), and the VITEK 2 system for the direct analysis of urine samples. First, we selected positive urine samples by flow cytometry using UF5000, establishing the cut-off for positive at 150 bacteria/mL. After confirming the identification using MALDI-TOF MS and filtering the urine samples for Escherichia coli, we directly tested the AST N388 card using VITEK 2. We tested a total of 211 E. coli from urine samples. Cefoxitin, ertapenem, imipenem, gentamicin, nalidixic acid, ciprofloxacin, fosfomycin, and nitrofurantoin had no major important errors (MIE), and ampicillin, cefuroxime, and tobramycin showed higher MIEs. Cefepime, imipenem, and tobramycin had no major errors (ME). Fosfomycin was the antibiotic with the most MEs. The antibiotic with the most minor errors (mE) was ceftazidime. The total categorical agreement (CA) was 97.4% with a 95% CI of (96.8–97.9)95%. The direct AST from the urine samples proposed here was shorter by one day, without significant loss of sensibility regarding the standard diagnosis. Therefore, we hypothesize that this method is more realistic and better suited to human antibiotic concentrations.

Antibiotic Resistance in the Uropathogenic Enterobacteria Isolated from Patients Attending General Reference Hospital (GRH) of Niamey, Niger

“…The method of Vitek-2 is regarded as an automatic identification system for microorganisms to show the phenotype of the isolates tested and able to determine the sensitivity or resistance of an isolate to antibiotics [24].…”

Current and Future Flow Cytometry Applications Contributing to Antimicrobial Resistance Control

“…Studies reported the use of FCM for the selection of positive urine specimens, followed by bacterial identification with MALDI-TOF MS and then direct testing AST with the VITEK 2 system to reduce the waiting time for results by up to one day [ 54 , 64 ]. In addition, FCM combined with DiBAC4(3), a membrane potential-sensitive dye, enabled direct AST in urine samples [ 37 ].…”

“…The FCM instrumental platforms could be included in such integrated trans-sectorial surveillance programs as they can increase the surveillance throughput and decrease the time to results. Currently, FCM-based methodologies have already demonstrated their ability to detect antibiotic resistance bacteria in human and animal biological samples [ 54 , 62 , 64 , 98 ], and in environmental samples [ 88 , 99 , 100 ]. Williams et al (2017) [ 101 ] introduced an approach based on FCM for the detection and counting of E. coli O157:H7 pathogen directly in food (raw spinach) that proved more sensitive than the reference method.…”

A Hypothetical Approach to Concentrate Microorganisms from Human Urine Samples Using Paper-Based Adsorbents for Point-of-Care Molecular Assays

“…Technically, for a patient presenting symptoms of a urinary tract infection, any microbial concentration in the test results may indicate an infection. However, in order to be clinically diagnosed as a UTI, the microbial load should surpass a threshold of 10 5 colony-forming units per milliliter (CFU/mL) of urine [10]. In the realm of urinary tract infection detection, the gold standard diagnostic method involves the collection of urine samples, followed by a subsequent culture [11].…”