Comparison of In Vitro Activity of Tigecycline and Vancomycin against Methicillin-Resistant Staphylococci: An E-Strip and Broth Microdilution Study
Abstract: Methicillin-resistant Staphylococcus aureus (MRSA) and methicillin-resistant coagulase-negative staphylococci (MRCoNS) are important causes of healthcare-associated and community-onset infections. Vancomycin remains a key agent for serious resistant Gram-positive infections, while tigecycline has broad in-vitro activity against staphylococci. Accurate MIC testing is important when reduced glycopeptide susceptibility is suspected. Objective: To compare the in-vitro activity of tigecycline and vancomycin against MRSA and MRCoNS using E-strip MIC testing and broth microdilution (BMD) methods. Methods: This cross-sectional laboratory study was conducted in the Department of Microbiology, Government Medical College, Kota, Rajasthan, from March 2025 to February 2026. Two hundred clinical staphylococcal isolates were identified by standard microbiological methods. Methicillin resistance was assessed using cefoxitin disk diffusion. Vancomycin susceptibility was screened using vancomycin screen agar and evaluated by E-strip and BMD; Tigecycline MICs were assessed by E-strip and BMD. Results: Of 200 isolates, 172 (86.0%) were S. aureus and 28 (14.0%) were CoNS. Among S. aureus, 116/172 (67.4%) were MRSA; among CoNS, 21/28 (75.0%) were MRCoNS. Tigecycline MICs were ?0.5 ?g/mL for all MRSA (116/116) and MRCoNS (21/21) by both E-strip and BMD. Vancomycin E-strip and BMD identified one vancomycin-resistant MRSA isolate (1/116; 0.9%) and no resistant MRCoNS isolates (0/21). The study recorded one MRCoNS screen-agar-positive isolate, but this finding was not confirmed by E-strip or BMD. Conclusion: Tigecycline showed excellent in-vitro activity against all tested MRSA and MRCoNS isolates, including the single MRSA isolate resistant to vancomycin by confirmatory MIC methods. These findings support tigecycline as a potential option for selected Staphylococcal infections.
Keywords: Staphylococcus aureus; coagulase-negative staphylococci; MRSA; MRCoNS; tigecycline; vancomycin; minimum inhibitory concentration; broth microdilution
How to Cite?: Dr. Anu Mahi, Dr. Anita E. Chand, "Comparison of In Vitro Activity of Tigecycline and Vancomycin against Methicillin-Resistant Staphylococci: An E-Strip and Broth Microdilution Study", Volume 15 Issue 11, November 2026, International Journal of Science and Research (IJSR), Pages: 222-225, https://www.ijsr.net/getabstract.php?paperid=SR261106092312, DOI: https://dx.doi.org/10.21275/SR261106092312