Vitek 2 compact device

The clinical data of the recruited patients were collected and subjected to further investigation. Complete blood count, electrolyte levels, coagulation test results, liver and kidney function, and serum calcium, phosphorus, magnesium, and C-reactive protein levels were assessed according to the manufacturer’s guidelines. Blood cultures for each patient were obtained, and cultures from different sites, including tracheal aspirate, cerebrospinal fluid (CSF), urine, and central venous catheter (CVC) analyses, were obtained only when clinically indicated. Cultures from the blood samples were incubated in a BACT/ALERT3D system (Biomerieux, France), whereas other cultures were incubated on plates containing suitable media. A VITEK2 Compact device (Biomerieux, France) was used to identify and test for antibiotic susceptibility in the positive cultures.

For all P. aeruginosa strains, the antibiotic susceptibility testing (AST) was performed by the agar dilution method with the automatic Vitek^®2 compact device (BioMérieux, Inc. Hazelwood, MO, USA). Briefly, 40 µL of the prepared inoculum was added into the AST test card, containing premeasured dried amounts of a specific antibiotic combined with the culture medium. The growth turbidity was measured every 15 min for a maximum incubation of 18 h at 35.5 ± 1 °C by the wavelength of 660 nm in each well at 16 different positions and repeated in triplicate. The antibiotics and interpretation used in this study were undertaken from the Clinical and Laboratory Standards Institute (CLSI) document M100 recommendation [42 ]. The used antibiotics were divided into six classes, namely: (i) aminoglycosides (amikacin), (ii) carbapenems (doripenem, imipenem, meropenem), (iii) cephalosporins (ceftazidime, cefepime), (iv) fluoroquinolones (ciprofloxacin and levofloxacin), (v) penicillins with beta-lactamase inhibitors (piperacillin/tazobactam), and (vi) cephalosporins with beta-lactamase inhibitor (cefoperazone/sulbactam). For interpretation, the MDR definition is the resistance to three or more antimicrobial classes [43 (link),44 (link),45 (link),46 (link)].

A string test-positive K. pneumoniae strain (HKE9) was isolated from the blood of an outpatient in the clinical laboratory of the First Affiliated Hospital of Xi’an Jiaotong University, Xi’an, Shaanxi Province, China. The HKE9 was resistant to most cephems and determined as an ESBL-producing strain. This study was approved by the ethics committee of the First Affiliated Hospital of Xi’an Jiaotong University.
An antibiotic susceptibility test was performed using a VITEK 2 Compact device (bioMérieux Inc., Marcy-l’Étoile, France) with VITEK 2 AST-GN 09. The interpretation of susceptibility data followed the CLSI M100 31st Edition. The HKE9 strain was tested for ESBL production by disk diffusion test, and K. pneumoniae ATCC 700603 (positive) and E. coli ATCC 25922 (negative) were used as quality control and performed as required in the manufacturer’s handbook.