Vitek 2 gp id card

Staphylococcus aureus identification was performed using either the VITEK® 2 GP ID card or the VITEK® MS system (bioMérieux, Marcy l’Etoile, France).

According to the diagnostic routine at the Department of Medical Microbiology and Hospital Hygiene of the Medical Faculty of Otto-von-Guericke University Magdeburg, Columbia CNA agar with 5% sheep blood (aerobic), Schaedler/Schaedler KV agar (anaerobic) and Schaedler broth (media obtained from Fisher Scientific GmbH, Schwerte, Gemany) were inoculated with the tissue biopsy taken.
Species identification was performed both biochemically, using a VITEK^® 2 GP ID card and a VITEK^® 2 XL device (Biomérieux, Nürtingen, Germany) as well as by MALDI-TOF MS (Vitek-MS, Biomérieux, Nürtingen, Germany).
Susceptibility testing was carried out using MIC test strips (Liofilchem S.r.l., Roseto degli Abruzzi (Teramo), Italy).

Blood culture broth from signal-positive bottles was aspirated and Gram staining was performed.
Samples exhibiting gram-positive cocci in pairs, chains or gram-positive cocci of uncertain morphological arrangement were inoculated onto 2% horse blood agar and 5% sheep blood agar, the latter with a 5 µg optochin disc placed in the main inoculating zone, as per routine laboratory standard operating procedures (SOPs). Both plates were incubated in 5% CO₂ at 37 °C and inspected after 24 and 48 h. Streptococcus pneumoniae was identified by the presence of alpha-haemolytic streptococci with a zone of inhibition around the optochin disk ≥ 14 mm diameter.¹⁴ Alpha-haemolytic streptococci with zones of inhibition < 14 mm diameter were further identified using the Vitek 2 GP-ID card (BioMérieux, Marcy-l’Etoile, France), according to the manufacturer’s instructions.

E. faecium Am5 was isolated from Apis mellifera larvae gut provided through the Faculty of Agriculture, University of Alexandria, Egypt. The triturated gut was cultivated on De Man-Rogosa-Sharpe (MRS; HiMedia, India) at 37 °C for 24 h. The Am5 isolate was biochemically identified using a VITEK 2 GP ID card (BioMérieux, France). Pure bacterial culture was stored at -20 °C in MRS broth supplemented with 50% (v/v) glycerol until further use. To investigate hemolytic activity, Am5 was cultivated on 5% (v/v) blood agar plates and incubated at 37 °C for 24 h.

According to previously published methods, the recovery of enterococci from retail chicken carcasses was achieved [10 (link)]. Species verification was completed using the Vitek-2 system with Vitek-2 GP-ID cards (bioMérieux, Marcy l’Etoile, France). Enterococcus spp. resistance to ten antimicrobials was evaluated using a Vitek AST-P592 panel (bioMérieux) that tested the specified species (E. faecalis/E. faecium) for the following antimicrobials: ciprofloxacin, erythromycin, ampicillin, high-level gentamicin, high-level streptomycin, vancomycin, teicoplanin, tigecycline, tetracycline, and linezolid. According to the manufacturer’s instructions, the isolates were considered susceptible, intermediate, or resistant [8 (link)]. The CLSI guidelines were used to classify isolates as resistant and susceptible. The multidrug resistance profile was denoted by resistance to at least one antimicrobial in three or more antimicrobial classes [11 (link)]. E. faecium ATCC29212 was used as a control strain.
Among the 16 linezolid-resistant Enterococcus (LRE) isolates (MIC (minimum inhibitory concentration) of ≥8.0 mg/L), as well as among a selection (n = 20) of the linezolid-positive Enterococcus strains, the presence or absence of the optrA, poxtA, and cfr genes was evaluated using a multiplex PCR, according to Egan et al. [12 (link)].