Emerging Resistance of Filamentous Bacteria in the Oral Cavity of Hiv-Positive Patients in Tehran, Iran Publisher Pubmed



Narimani O ; Shahedin GJ ; Tamai IA ; Bakhtiari AA ; Fard RMN
Source: Iranian Journal of Medical Sciences Published:2026

Abstract

Background: In general, human immunodeficiency virus (HIV) weakens the immune system, making patients prone to oral infections such as gum and dental diseases. Filamentous bacteria (actinomycetes) can multiply in these patients, leading to treatment-resistant infections. Routine antimicrobial drugs such as penicillin G, amoxicillin, and tetracycline are widely used for treatment. However, antibiotic resistance is rapidly increasing worldwide. Therefore, the major target of the present study was to assess the prevalence and antibiotic susceptibility of filamentous bacteria in the oral cavity of HIV-positive patients in Tehran, Iran. Methods: In this cross-sectional study, oral swabs were collected from 205 HIV-positive patients in an academic behavioral disease clinic, Tehran, Iran, and immediately transported to the laboratory under cold chain conditions. Bacterial cultures were prepared on differentiate media, and primary identification was carried out using biochemical and microscopic assays. Furthermore, deoxyribonucleic acid (DNA) extraction was carried out for molecular identification of the bacterial isolates using 16S rRNA (ribosomal ribonucleic acid) sequencing and polymerase chain reaction (PCR). Antimicrobial susceptibility of the isolates was assessed using the disk diffusion method for selected antimicrobials. Results: In general, filamentous bacteria were identified in 5.3% of HIV-positive patients, including Nocardia (2.9%) and Streptomyces (2.4%) species. Molecular identification and biochemical assessments verified these findings. The highest prevalence rate of the bacteria was observed in males (74.1%) and individuals aged 41–60 years. Phylogenetic analysis revealed significant genetic similarities in the identified strains. These bacteria were susceptible to trimethoprim-sulfamethoxazole but resistant to other antimicrobials. Conclusion: In conclusion, filamentous bacteria such as Nocardia and Streptomyces species show high prevalence rates in HIV-positive patients. Accurate identification using molecular techniques and antimicrobial susceptibility assessments can improve infection management, thereby bringing patients’ relief. This study highlights the importance of early detection and suggests further studies on the prevalence and resistance patterns of filamentous bacteria in HIV-positive patients. © Iranian Journal of Medical Sciences.