Prevalence, Comparison of Diagnostic Methods, Antibiogram, and Genotyping of Arcobacter spp. in Diarrheal Cases Referring to Clinical Centers in Iran

Arcobacter is an emerging bacterium that may cause watery diarrhea and septicemia in humans. This study aimed to investigate the prevalence of Arcobacter spp. in diarrheal stool specimens using culture and molecular methods, their genetic diversity, and their resistance to different antibiotics in patients referring to clinical centers in Arak, Iran.

In this descriptive cross-sectional study, diarrheal stool specimens were collected from 230 patients over a two-month period from July to September 2016. The samples were tested for the presence of Arcobacter species. Suspected colonies were subjected to biochemical tests and identified by phenotypic methods. In addition, antimicrobial susceptibility testing was performed using the disk diffusion method. Arcobacter spp. were also directly detected  by multiplex-PCR.

Out of 230 samples, 20 samples (8.69%) were positive in culture method, and 44 samples (19.13%) were positive in PCR method, all culture-positive samples were also positive in PCR method. Rep-PCR indicated 14 different rep types among Arcobacter spp. isolated from patients with gastroenteritis. All Arcobacter isolates were resistant to cefazolin, ceftazidime, and nalidixic acid. The isolates showed high susceptibility to tetracycline, gentamicin, ampicillin, amikacin, meropenem, erythromycin, and ciprofloxacin.

To the best of our knowledge, this is the first study conducted in Iran to isolate Arcobacter spp. from patients with gastroenteritis. The results indicate that Arcobacter spp. are one of the main causes of acute diarrhea in humans. The research outcomes show that Arcobacter spp. could be considered as the etiology of gastrointestinal infections in humans.