Ceftriaxone cro

Antimicrobial susceptibility testing of 60 Salmonella isolates was performed on Mueller-Hinton agar (Oxoid, Milano, Italy) by disc diffusion method (Kirby-Bauer), according to Clinical and Laboratory Standard Institute (CLSI) guidelines [50 ]. A set of 16 antibiotics has been defined: sulfamethoxazole/trimethoprim (STX, 25 µg), kanamycin (K, 30 µg), gentamicin (CN, 10 µg), nalidixic acid (NA, 30 µg), tetracycline (TE, 30 µg), ampicillin (AMP, 10 µg), chloramphenicol (C, 10 µg), ciprofloxacin (CIP, 5 µg), cefotaxime (CTX, 30 µg), amoxicillin/clavulanic acid (AMC, 30 µg), enrofloxacin (ENR, 5 µg), tobramycin (TOB, 10 µg), levofloxacin (LEV, 5 µg), imipenem (IPM, 10 µg) and ceftriaxone (CRO, 30 µg) disks (Oxoid, Milano, Italy) were used.
A 0.5 McFarland bacterial suspension was prepared from each isolate in saline solution and spread on Mueller-Hinton agar. After incubation at 37 °C for 24 h, the isolates were classified as resistant (R), susceptible (S) or intermediate (I) after determination of the diameters of inhibition zones. The interpretation of the results was performed following CLSI indications [50 ].

Antimicrobial susceptibility test was performed using the modified Kirby–Bauer disk diffusion method according to the clinical laboratory standard institute guidelines [16 ]. The inoculums was prepared by suspending 4–5 isolated colonies of the same morphology in 5 ml of sterile physiological saline equal to a 0.5 McFarland standards used as a reference to adjust the turbidity of bacterial suspensions. Swab was inoculated on Mueller–Hinton agar (MHA) plates supplemented with 5 % defibrinated sheep blood to obtain confluent growth, antibiotic disks was placed and incubated at 35–37 °C under 5 % CO₂ atmosphere for 20 h. The following antimicrobials were used with their respective concentration: penicillin G (P) (10 IU), ampicillin (AMP) (10 μg), erythromycin (E) (15 µg), gentamicin (CN) (10 µg), vancomycin (VA) (30 µg), norfloxacin (NOR) (10 μg), ciprofloxacin (CIP) (5 µg), ceftriaxone (CRO) (30 µg), and chloramphenicol (C) (30 µg) (Oxoid, UK).