Pasteur Institute of Iran

---

Introduction: Staphylococcus aureus is among the primary cause of hospitals and community-acquired infections. The emergence of methicillin-resistant S. aureus (MRSA) strains has resulted in the treatment failure of the infections caused by these bacteria. Hence, regional data on antibiotic resistance of S. aureus strains is necessary to adopt appropriate treatment regimens. This study aims to identify the diversities and their frequencies among MRSA isolates by molecular analysis of four genes. Methods: In a cross-sectional study, 100 S. aureus isolates from patients hospitalized in two hospitals of Ahvaz, Iran were collected and identified. The MRSA isolates were identified by phenotypic method and amplification of the mecA gene. The diversity of MRSA isolates was investigated by amplification of the coa, spa, aroA, and gap genes followed by RFLP analysis using the AluI, HindIII, TaqI and RsaI restriction enzymes. Results: In this study, we identified 50 MRSA isolates. Based on the analysis of coa gene, 8 types, spa gene 5 types and 17 subtypes, coa gene with AluI 13 types, and spa with HindIII 13 types were identified. Also, the RFLP analysis of gap gene with AluI revealed 3 types, and of aroA gene with TaqI and RsaI, 3 types and 2 subtypes, respectively.  Conclusion: Our PCR-RFLP analysis revealed that diversities are present among MRSA isolates originated from clinical samples and showed that this method is simple, reproducible, and cost-effective. 

---

Introduction: Understanding the epidemiological and clinical characteristics of different tuberculosis strains is crucial for developing improved diagnostic tools, drugs, and vaccines for tuberculosis management. This study aimed to investigate the molecular epidemiology of Mycobacterium tuberculosis using spoligotyping, a widely used molecular typing method, to understand the genetic diversity and transmission dynamics of M. tuberculosis, on isolates obtained from patients with pulmonary tuberculosis in central Kerala. Methods: In a prospective study at a tertiary care hospital, 404 respiratory specimens from patients with symptoms suggestive of TB were collected. Specimens underwent Ziehl-Neelsen staining, culture in liquid (BD BACTEC™ MGIT™) and solid (Lowenstein-Jensen) media, and standard drug susceptibility testing with the MGIT system. Molecular analysis involved conventional PCR amplification of genomic DNA to generate sufficient genetic material for analysis, using species-specific and primers targeting the direct repeat region, followed by spoligotyping to assess the genetic diversity of the M. tuberculosis strains. Results: Out of 404 samples from individuals with suspected pulmonary TB, Mycobacteria were cultured from 48 [11.9%] of the samples. Amongst the 48 culture-positive M. tuberculosis isolates, 20 (41.66%) were sensitive to all five first-line anti-TB drugs, and 3 (6.2%) were resistant to all five drugs. Spoligotyping of the 47 isolates showed that 36.1% [n=17] of the isolates belonged to the M. tuberculosis EAI3 (East African-Indian) family, followed by 27.6% (n=13) M. tuberculosis EAI5 and 21.2% (n=10) M. tuberculosis CAS (Central Asia). Other families observed in this study, although less prevalent, were M. tuberculosis Beijing, 8.5% (n=4), family 33, 4.3% (n=2), and Mycobacterium bovis-BCG family, 2.1% (n=1). Conclusion: This study explored the genetic diversity and distribution of circulating M. tuberculosis strains in central Kerala. Genotyping M. tuberculosis strains provides valuable insights into TB transmission and progression, which can inform the development of effective public health control strategies.