Norfloxacin

The resistance pattern of isolates against 15 antibiotics including 5 fluoroquinolones was determined by disc diffusion method on Mueller-Hinton agar (Merck, Germany) as described by the Clinical Laboratory Standards Institute (CLSI 2017) guidelines³⁶ . The antibiotic disks used were as follows: amikacin (30 μg), aztreonam (30 μg), cefepime (30 μg), ceftazidime (30 μg), ceftriaxone (30 μg), ciprofloxacin (5 μg), gatifloxacin (5 μg), norfloxacin (5 μg), gentamycin (10 μg), imipenem (10 μg), levofloxacin (5 μg), ofloxacin (5 μg), piperacillin (100 μg), piperacillin/tazobactam (100 μg/10 μg), and tobramycin (10 μg) (MAST Co., Berkshire, UK). Drug-resistant patterns were defined as follows: MDR isolates (resistant to at least three antibiotics belonging to different chemical classes), XDR strains (resistant to at least one agent in all but two or fewer antimicrobial groups), and PDR strains (resistant to all antimicrobial classes)^{37 (link)}. E. coli ATCC 25922 and P. aeruginosa ATCC 27853 were used as quality control strains.

All 12 isolates were tested for their antibiotic susceptibility to a panel of 11 antibiotics, including ampicillin (10 mg), piperacillin-tazobactam (30/6 mg), amoxicillin and clavulanic acid (20/10 mg), ceftazidime (10 mg), cefepime (30 mg), norfloxacin (10 mg), levofloxacin (5 mg), amikacin (30 mg), imipenem (10 mg), meropenem (10 mg), and chloramphenicol (30 mg) (Mast Group, Merseyside, UK), using a disk diffusion method, according to the European Committee on Antimicrobial Susceptibility Testing protocol (57 ). The antibiotics chosen were those that are the most frequently used in clinical settings in Armenia. E. coli isolates were identified as “ESBL-producing” upon the confirmation of their resistance to cefepime and ceftazidime antibiotics.

The identification and susceptibility profiles of these four and other E.coli isolates were reported previously (50 (link)); in brief, each isolate was tested against a panel of 10 antibiotics using the disk diffusion method. The antibiotics included were ampicillin (10 mg), piperacillin-tazobactam (30/6 mg), amoxicillin-clavulanic acid (20/10 mg), ceftazidime (10 mg), cefepime (30 mg), norfloxacin (10 mg), levofloxacin (5 mg), amikacin (30 mg), imipenem (10 mg), meropenem (10 mg), and chloramphenicol (30 mg) (Mast Group, Merseyside, UK) according to the European Committee on Antimicrobial Susceptibility Testing (EUCAST) protocol (52 ). Isolates were determined to be ESBL producing if they showed resistance to ceftazidime and cefepime.

Out of 360 ATMs at four locations in Hamadan (number provided by the central bank of the islamic republic of Iran) 96 ATMs were randomly selected. Using a sterile swab soaked in saline, samples were taken from the surfaces of the ATM keyboards. The swab was put into nutrient broth media and transferred to the microbiology laboratory of the University of Medical Sciences, Hamadan and incubated for 30 min. In order to differentiate microorganisms, swabs were cultured on blood agar and MacConkey agar plates and incubated at 37°C for 18–24 hours. Identification of the isolated bacteria was performed using standard microbiological methods [16 ]. For all isolated strains, antibacterial susceptibility was tested using the standard Kirby-Bauer disk agar diffusion (DAD) method on Mueller Hinton agar (Merk Co., Germany) according to the clinical and laboratory standards institute guidelines (CLSI; 2015, M100-S25) [17 (link)] using gentamicin (10 µg), vancomycin (30 µg), trimethoprim/sulfamethoxazole (25 µg), amikacin (30 µg), tobramycin (10 µg), cephalotin (30 µg), norfloxacin (5 µg), and ceftizoxim (30 µg) disks (Mast Co.UK).
All statistical analyses were performed using the SPSS software package, version 21.