Emergence of staphylococcal cassette chromosome mec type I with high-level mupirocin resistance among methicillin-resistant Staphylococcus aureus

• Published in: Asian Pacific Journal of Tropical Biomedicine
• Main Authors: Prabhu Raj Joshi, Mahesh Acharya, Rajan Aryal, Kamal Thapa, Trishna Kakshapati, Rathanin Seng, Anjana Singh, Sutthirat Sitthisak
• Format: Article in Journal/Newspaper
• Language: English
• Published: Wolters Kluwer Medknow Publications 2017
• Subjects: Methicillin-resistant Staphylococcus aureus; Staphylococcal cassette chromosome mec types; Mupirocin resistance; Nasal carriage; Arctic medicine. Tropical medicine; RC955-962; Biology (General); QH301-705.5; Arctic
• Online Access: https://doi.org/10.1016/j.apjtb.2016.12.002; https://doaj.org/article/7a20ba887087425eb19ad5f0a5bd2f0d

Objective: To investigate the molecular epidemiology and antimicrobial resistance patterns of methicillin-resistant Staphylococcus aureus (MRSA) among healthcare workers and patients. Methods: MRSA isolates were recovered from nasal swabs collected at a tertiary care hospital of Nepal and confirmed on the basis of Gram staining, conventional biochemical tests, and PCR amplification of mecA gene. PCRs were also used for detection of the different resistance genes and staphylococcal cassette chromosome (SCC) mec types. Antibiotic susceptibility patterns of isolates were assessed by disc diffusion method and minimum inhibitory concentrations were determined by E-test. Results: A total of 29 MRSA were isolated from 536 nasal swabs (5.4%) of health care workers and patients at a tertiary care hospital in Nepal. All isolates were susceptible to amikacin, gentamicin, vancomycin (minimal inhibitory concentrations < 2 μg/mL), tigecycline, tetracycline, nitrofurantoin, rifampicin, quinupristin-dalfopristin, and linezolid. Among the 29 MRSA isolates, resistance to erythromycin (72%), ciprofloxacin (75%), co-trimoxazole (62%), clindamycin (10%), and chloramphenicol (10%) was found, and fifteen isolates (51%) exhibited high-level mupirocin resistance (minimal inhibitory concentrations > 1 024 μg/mL). Fourteen isolates were found harboring the mupA gene and one isolate was found carrying the novel mupB gene. High prevalence (68%) of SCCmec I type was found, followed by SCCmec V (13%) and SCCmec III (3%) among all the MRSA isolates. Conclusions: We found the emergence of SCCmec type I with high-level mupirocin resistance among MRSA in Nepal. Data also suggest that MRSA SCCmec type V strain has spread from the community to the hospital.