Vitek 2 ast card

Antibiotic susceptibility to extended-spectrum β-lactam and carbapenem antibiotics was evaluated using a VITEK 2 Compact (bioMérieux) with VITEK® 2 AST cards (bioMérieux). The test was run according to the manufacturer’s instructions. Furthermore, for isolates defined as “pathogenic/sensitive” a minimum inhibitory concentration (MIC) test was conducted for the following antibiotics: tetracycline, streptomycin, polymyxin B, gentamycin, nitrofurantoin, chloramphenicol, trimethoprim, cefuroxime, cefaclor, cefazolin, and amikacin. The tests were conducted using the E-Test (Liofilchem) according to the manufacturer’s instruction. Briefly, for each strain, 0.5 McFarland was spread on Mueller Hinton agar (Merck, Darmstadt, Germany) plates and exposed to a strip of varying antibiotic concentrations. The plates were incubated for 24 h in 37 °C, and the zone of growth inhibition was assessed visually to determine the MIC.

This retrospective study was conducted between Jan 2011 to Dec 2016 (for a period of five years). Data collection was based on the systematic review of all-patient charts from medical records department in order to determine the clinical and microbiological pectrum, 191 patients records, definitely diagnosed with IE, based on modified Dukes criteria were re-viewed and included. Demographic details such as age, sex, clinical findings, and antibiotic usage were analysed from these cases. Three sets of blood cultures, BacT/Alert FNaerobic and SN aerobic bottles per set (bioMerieux, Marcy l’Etoile, France), were submitted to the microbiology lab, within 24 hours of admission and immediately loaded into BACT/ALERT 3D system. Gram staining was performed on all the positive flagged bottles and further sub-cultured on Blood (COS bioMerieux, Marcy l’Etoile, France) and Chrome agar (COS bioMerieux, Marcy l’Etoile, France) plates and incubated at 37°C for 24h. The Vitek 2 (bioMérieux, Marcy l’Etoile, France) GN cards (ID GN panel) were used, for accurate identification of Gram-negative pathogens and Vitek 2 AST Cards (N281 panel), for antimicrobial susceptibility testing.
The Vitek 2 GP cards (ID GP) were used, for accurate identification of Gram-positive pathogens, and Vitek 2 AST cards for antimicrobial susceptibility testing.

Antimicrobial susceptibility testing (AST) of the clinical isolates was performed using the gram-negative and gram-positive Vitek2® AST cards (N280, N281, and P628) (bioMérieux, Inc., Durham, NC), as per the manufacturer's instructions. The minimum inhibitory concentration for colistin was determined by the Clinical and Laboratory Standards Institute (CLSI) broth microdilution method.¹² The antibacterial drugs tested against gram-negative pathogens included amikacin, cefepime, cefoperazone/sulbactam, ceftazidime, ciprofloxacin, levofloxacin, imipenem, meropenem, piperacillin/tazobactam, and chloramphenicol. The antibacterial drugs tested against gram-positive organisms included vancomycin, teicoplanin, ciprofloxacin, linezolid, erythromycin, clindamycin, and doxycycline. Multidrug resistance was defined as resistance to two or more different classes of antimicrobials.¹³ After processing, the samples were discarded as per the COVID-19 biomedical waste management guidelines.¹⁴

Carbapenem-resistant A. baumannii bloodstream isolates from patients with CRAB between June 2016 and December 2019 at Chonnam National University Hospital (a 1,000-bed tertiary care hospital with eight ICUs in Gwangju, Korea) were stored at −80°C. Species identification was performed initially by matrix-assisted laser desorption ionization-time of flight mass spectrometry-based VITEK MS (bioMérieux, France) and VITEK 2 (bioMérieux) and was confirmed by using MLST-based identification as previously described (Gaiarsa et al., 2019 (link)). Carbapenem resistance was initially determined using the VITEK 2 AST Card (bioMérieux) and confirmed by broth microdilution test (Clinical and Laboratory Standards Institute, 2020 ). Duplicate CRAB isolates from the same patient were excluded.

All hospitalised cases with confirmed E. coli or enterococcal infection during the 8-weeks study period were reviewed to investigate possible hospital-acquired (HAI) infection and relationship with environmental contamination. The resistance profile of isolates from hospitalised cases was analysed by VITEK®2 AST Card and VITEK® 2 Systems Version: 08.02 (bioMérieux, France). The VITEK®2 cards used for testing enterococcal isolates do not include vancomycin analysis. The VITEK®2 GN97 cards for E. coli isolates analyse resistance to 19 antimicrobials and test for presumptive extended-spectrum beta-lactamase (ESBL) production. The cards used for Enterococcus species analyse resistance to 19 antimicrobials. The resistance profiles of suspected HAI cases were compared to those of faecal bacteria isolated from the environment. In our study, we used 6 antimicrobials for E. coli and 4 for Enterococcus species in the disc diffusion test (resources for the project did not allow testing using the VITEK® 2 System).