Flumequine

Antibiotic susceptible test was performed using disk diffusion method [1 ]. The bacterial cells were prepared by propagated the bacteria using Luria Broth (Oxoid, England), followed by centrifugation at 14,500 rpm for 10 min using MiniSpin (Eppendorf, Germany). The collected bacterial cells were adjusted into 10⁹ colony forming unit (CFU) using physiological saline and monitored using Biophotometer (Eppendorf, Germany). The suspensions were swabbed on Mueller-Hinton agar (Oxoid, England) using sterile cotton bud. The inoculated media was then left for 10 min before antibiotic discs were placed onto the agar surface. 16 types of antibiotics tested were nalidixic acid (30 µg/disk), oxolinic acid (2 µg/disk), compound sulfonamides (300 µg/disk), doxycycline (30 µg/disk), tetracycline (30 µg/disk), novobiocin (30 µg/disk), chloramphenicol (30 µg/disk), kanamycin (30 µg/disk), sulfamethoxazole (25 µg/disk), flumequine (30 µg/disk), erythromycin (15 µg/disk), ampicillin (10 µg/disk), spiramycin (100 µg/disk), oxytetracycline (30 µg/disk), amoxicillin (25 µg/disk), and fosfomycin (50 µg/disk) (Oxoid, England). After 24 h of incubation period, diameter of the inhibition zone was measured in millimeter (mm) using a ruler and results were interpreted with reference to the standard provided by Clinical Laboratory Standards Institute [9 ].

Antimicrobial susceptibility test was conducted to further understand the exposure of the strain toward antibiotics by standard antibiotics disc and disc diffusion technique [20 (link)]. A suspension (100 µl) of fresh cultured of S. agalactiae <24 h on TSB, diluted to a turbidity equivalent to a MacFarland No. 0.5 standard solution, was spread onto triplicate Mueller–Hinton agar (Oxoid, England) plates, and tested against 18 chemotherapeutic agent discs namely nitrofurantoin (F - 50 µg), flumequine (UB - 30 µg), florfenicol (FFC - 30 µg), amoxylin (AML - 25 µg), doxycycline (DO - 30 µg), oleandomycin (OL - 15 µg), tetracycline (TE - 30 µg), ampicillin (AMP - 10 µg), lincomycin (MY - 15 µg), colistin sulfate (CT - 25 µg), oxolinic acid (OA - 2 µg), novobiocin (NV - 30 µg), spiramycin (SP - 100 µg), erythromycin (E - 15 µg), fosfomycin (FOS - 50 µg), neomycin (N - 10 µg), gentamicin (GM - 10 µg), and polymyxin B (PB - 30 µg) (Oxoid, England). The susceptibility test agars were incubated at 37°C for 24 h and the diameter of inhibition zones around the discs was measured and compared to the standard table for antimicrobial susceptibility provided by CLSI [21 ].