Caspian Journal of Internal Medicine

Background: Despite growing knowledge in microbiome studies data about the diversity of cultivable bacteria and their drug resistance patterns in patients with gastritis are scant.
Methods: Two gastric biopsies of 171 symptomatic patients were collected and examined by histological and microbiological methods. Viable bacteria were characterized using conventional techniques, and antimicrobial susceptibility of the isolates was detected.
Results: Acute gastritis, chronic gastritis, and peptic ulcers were detected in 3.5%, 86.5%, and 5.8% of the patients, respectively. Culturable bacteria were isolated from 71.3% of the patients, including Helicobacter pylori (H. pylori) (26.9%), Staphylococcus epidermidis (19.8%), Micrococcus (1.1%), Streptococcus viridans (S. viridans) (13.4%), Enterococcus faecalis (E. faecalis) (4.6%), Staphylococcus aureus (S. aureus) (1.7%), and Group D Streptococcus (7.1%). Single infection and coexistence of two and three types of bacteria were detected in 43.2%, 15.2%, and 5.2% of the patients, respectively. An odd ratio of 4.4 was measured for Staphylococcus spp. in patients with acute gastritis (P-value = 0.08). E-test results showed intermediate resistance to penicillin in 66.6% of the S. aureus isolates, while resistance to vancomycin was detected only in the S. viridans (30.4%). Resistance to linezolid was detected in 100%, 17.4%, and 16.7% of E. faecalis, S. viridans, and group D Streptococci isolates, respectively. A high frequency of resistance to penicillin, clindamycin, linezolid, erythromycin, and tetracycline was detected in S. epidermidis strains.
Conclusion: Our results highlighted the importance of Gram-positive bacteria in the etiology of gastritis. Resistance of these bacteria to different classes of antibiotics should be considered in the clinical setting.