Antimicrobial susceptibility testing of the isolated strains was performed using the disk diffusion method (modified Kirby–Bauer method) on Mueller–Hinton agar (HiMedia, India) as recommended by the CLSI, Wayne, United States.
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Susceptibility of the fluoroquinolones including nalidixic acid (30 µg), pefloxacin (5 µg), ciprofloxacin (5 µg), azithromycin (15 µg), chloramphenicol (30 µg), cotrimoxazole(1.25 µg/23.75 µg), cefixime (5 µg), and ceftriaxone (30 µg) (HiMedia Laboratories, India) was done. The results of the antibiotic susceptibility were determined on the basis of interpretative zone diameters as suggested by CLSI. For standardization,
Escherichia coliATCC-25922 was used as the control organism for antibiotic sensitivity.
Further, MICs of all isolates was checked using broth microdilution method as per CLSI guidelines.
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ciprofloxacin concentrations ranged from 0.06 to 16 µg/mL. pefloxacin HiComb (HiMedia),was used for determining the MIC of pefloxacin, which is available as Part A and Part B with concentration of 240 to 0.01 µg/mL and 30 to 0.001 µg/mL, respectively. Antimicrobial susceptibility testing was performed according to the manufacturer’s instructions and interpreted using CLSI guidelines.
E. coliATCC 25922 and
Pseudomonas aeruginosaATCC 27853 served as quality control strains.