Vitek automated system

K. pneumoniae ML2011 was collected in July 2004, from intensive care unit of the Military Hospital of Tunis (Tunisia). Identification of strains was performed by using both the VITEK automated system (bioMérieux, Marcy l'Etoile, France) and API 20 E system (bioMérieux, Marcy l'Etoile, France). Biochemical and serological confirmation of the identity of this strain was done at the Laboratory of Bacteriology, Military Hospital, Tunisia. E. coli DH5α and E. coli HB101 were used, respectively, for the transformation and conjugation experiments. E. coli BL21 and BL21 (DE3) (pLysS) were used for the resistance profile of the different strains and for the overexpression of SHV-104, respectively.

One milliliter of blood from sham and CLP group was cultured in Petri dishes with sheep blood and incubated for 48 hours at 37 °C in an aerobic atmosphere. Bacterial colonies identification was conducted using VITEK® automated system (BioMerieux, USA).

Blood cultures were performed at the microbiology laboratory using standard techniques via the automated vac+/alert system (Organon Teknika, Toronto, ON). Bacterial identification was performed using the Vitek automated system (bioMérieux, France).

Specimens came from the routinely clinical activity. GNB were isolated on Columbia 5% sheep blood agar (COS-bioMérieux, Marcy l’Etoile, France), lactose-containing Mac Conkey (bioMérieux, France), and chromogenic media for the detection of ESBL production (ESBL Brilliance agar-Oxoid, Basingstoke, UK) and carbapenem resistance (Brilliance CRE agar-Oxoid, UK). For bacterial identification, we used API 20E galleries (bioMérieux, France) or the Vitek automated system (bioMérieux, France). Sensitivity to antimicrobial agents was tested according to the Clinical Laboratory and Standards Institute (CLSI) criteria, by determining the minimum inhibitory concentration (MIC) with the Vitek system, which was supplemented when needed by the disk diffusion method [10 ].
The phenotypic confirmation of ESBL production was done using the synergy test between extended-spectrum cephalosporins and clavulanic acid and the double-disk synergy test with cefotaxime, ceftazidime, and cefepime with and without clavulanic acid [10 ,11 (link)]. Carbapenemase production was demonstrated either by the modified Hodge test or by combined disc methods (KPC, MBL, and OXA-48 Confirm kit, Rosco Diagnostica, Denmark) [10 ,12 (link),13 (link)].

Both aerobic and anaerobic cultures were performed for the blood and pus samples. Species identification and antimicrobial susceptibility were tested using VITEK automated systems (bioMérieux Vitek, USA), and interpreted according to guidelines established by the Clinical and Laboratory Standards Institute according to the Clinical and Laboratory Standards Institute (CLSI) criteria. Phenotypic confirmation of ESBL detection was performed using the double-disk diffusion method in our clinical microbiology laboratories, as recommended by the CLSI.

Aerobic and anaerobic cultures were performed for the blood samples. Species identification and antimicrobial susceptibility were tested using VITEK automated systems (bioMérieux Vitek, Hazelwood, MO, USA) and interpreted according to the Clinical and Laboratory Standards Institute (CLSI) criteria.
Blood culture results were classified as positive or negative based on the presence or absence of bacterial growth, respectively. The provisional oral report was provided to clinicians immediately after obtaining strain staining results (usually the next day). Blood culture positivity was defined as the detection of a microbiological pathogen within 6 days of incubation. The results of blood culture showing presence bacterial growth were considered negative if the microbiological pathogen could not be identified. Each positive blood culture result was assessed for contamination (false positivity) according to the established criteria [9 (link)]. Thereafter, all false-positive culture results were coded as negative.
Phenotypical confirmation of ESBL detection and susceptibility to ESBL-positive isolates were evaluated using the disk diffusion technique in our clinical microbiology laboratories, as recommended by the CLSI.