Ast gn card

All CRKP isolates were identified by matrix-assisted laser desorption ionization-time of flight mass spectrometry (MALDI-TOF MS; Bruker Daltonics, Germany), while the minimum inhibitory concentrations (MICs) of antibiotics were determined using the Vitek 2 system and the AST-GN card (bioMérieux, France). The Kirby–Bauer disk diffusion method was employed as a supplementary susceptibility test. Carbapenem resistance of CRKP was defined as a minimum inhibitory concentration of ≥4 μg/mL for meropenem/imipenem or ≥2 μg/mL for ertapenem with reference to the CLSI criteria (Clinical and Laboratory Standards Institute, 2021 ).

Antimicrobial susceptibilities were performed using the Vitek 2 system and the AST-GN card (bioMérieux, Marcy l'Etoile, France). Values were interpreted according to breakpoint table for interpretation of MIC values and zone diameters (European Committee on Antimicrobial Susceptibility Testing, 2016 ). Colistin susceptibility assay was performed according to recommendation of joint CLSI-EUCAST guidelines: http://www.eucast.org/fileadmin/src/media/PDFs/EUCAST_files/General_documents/Recommendations_for_MIC_determination_of_colistin_March_2016.pdf.

This study was conducted from January 2015 to September 2017. All the Enterobacteriaceae isolates were identified and the minimum inhibitory concentrations(MICs) of antibiotics were determined using the Vitek 2 system and the AST-GN card (bioMérieux, France) at the First Affiliated Hospital of Jiamusi University, a 1600 beds hospital. Disk diffusion method was used as a supplementary susceptibility test. As CNSE were considered only those isolates that confirmed as Carbapenems-nonsusceptible (either of ertapenem, imipenem or meropenem) according to Clinical and Laboratory Standard Institutes (CLSI-2016) criteria. Escherichia coli ATCC 25922 and E. coli J53 (sodium azide resistant) were used as the control for antimicrobial susceptibility test and recipient strain for conjugation experiment, respectively.

The VITEK-2 Compact automatic microbiological analyzer AST-GN card (bioMérieux, France) was used for routine antimicrobial susceptibility testing. Minimum inhibitory concentration (MIC) defined as the lowest compound concentration (µg/ml) required to stop bacterial growth was determined by using the microbroth dilution method. Imipenem (IPM), meropenem (MEM), amikacin (AK), levofloxacin (LEV), tigecycline (TIG), polymyxin B (PB), and ceftazidime–avibactam (CAZ–AVI) were used to determine the MIC by the microbroth dilution method. ATCC 25922, ATCC 700603, and BAA-1705 were used as quality control strains. Three parallel assays were performed for each sample. The IPM, MEM, AK, LEV, PB and CAZ-AVI results were interpreted based on CLSI criteria (CLSI, 2020 ), whereas the TIG results were interpreted based on the European Committee on Antimicrobial Susceptibility Testing (EUCAST) (The European Committee on Antimicrobial Susceptibility Testing, 2020 ) breakpoint recommendations.

Carbapenem resistance of Enterobacteriaceae was screened using the meropenem disk alone as previously described [18 (link)]. Susceptibility tests were performed using the Vitek 2 system and the AST-GN card (bioMe’rieux). Breakpoints values were those recommended by the EUCAST 2014 [19 ]. Escherichia coli ATCC 25922 was used as quality control strain. ESBL activity was evaluated using the double-disk synergy test as previously described [20 (link)]. Colistin susceptibility was evaluated by broth microdilution in Mueller–Hinton broth II (MHBII) according to Clinical and Laboratory Standards Institute guidelines [21 ].

The antimicrobial susceptibility of the K. pneumoniae strain was determined using the broth microdilution method according to the Clinical and Laboratory Standards Institute (CLSI) guidelines (64 (link)). Briefly, the MICs of antibiotics were determined using the Vitek 2 system and ASTGN card (bioM é rieux, France) for the isolated CRKP strains. The Kirby Bauer disk diffusion method was used as a supplementary drug sensitivity test. Strains were designated susceptible (S), intermediate (I), and resistant (R) based on their respective MIC values and CLSI-defined interpretive criteria.

Forty clinical CRKP isolates were collected from patients with infectious diseases at the First Affiliated Hospital of Jiamusi University from October 2015 to January 2019. The CRKP isolates were characterized by using the Vitek 2 system and the AST-GN card (bioMérieux, France). Routine multilocus sequence typing (MLST) and polymerase chain reaction (PCR) were performed to verify the presence of carbapenemase and ESBL genes (Table 1).