The incidence of infections caused by the multidrug-resistant (MDR) Gram-positive bacteria is increasing despite the advances in antibacterial therapy over the last few years. The most problematic pathogens include Methicillin-resistant staphylococcus aureus (MRSA). Methicillin resistance in Staph.aureus is associated with resistance to several commonly used antimicrobial agents such as Amoxicillin-Clavulanic Acid, Ceftizoxime, Ofloxacin, Amikacin, Azithromycin and Clindamycin. Glycopeptides such as Vancomycin have traditionally been considered as the drug of choice in the treatment of infection caused by these organisms. But Strains of MRSA with reduced susceptibility to glycopeptides have been reported from several parts of the world including India. Other than this linezolid a novel Oxazolidinone has potent activity against a variety of Gram-positive bacteria including MRSA and are used to treat more severe infections that do not respond to glycopeptides such as Vancomycin. But Linezolid resistant Staph.aureus (LRSA) first isolated in 2001, since then many other cases of Linezolid resistant MRSA have been reported in various parts of the world. The aim of this study was to compare and analyse the Resistance of vancomycin and linezolid Against MRSA in a Tertiary Care Centre at Southern Rajasthan. Modified Kirby Baurer disc diffusion method was used for antimicrobial sensitivity testing of all samples. Vancomycin and Linezolid which were having 100% sensitivity to MRSA earlier even found resistance in some isolates of MRSA in the present study. The prevalence rate of vancomycin resistance (VRSA)-13% and Linezolid resistance (LRSA)–12% was found in clinical isolates of Staph. Aureus samples. This has resulted in a situation in which very few options are available for treating infections caused by MRSA. So urgent measures are required to prevent the development of resistance among them and the same time there is  simultaneous need for development of newer agents active against VRSA and LRSA.

REFERENCES 

1. Lowy FD. Antimicrobial resistance: the example of Staphylococcusaureus. J Clin Invest. 2003;111(9):1265-73. doi: 10.1172/JCI18535, PMID 12727914.
2. Raygada JL, Levine DP. Managing CA-MRSA infections: current and emerging options. Infect Med. 2009;26(2):42-4.
3. Jensen SO, Lyon BR. Genetics of antimicrobial resistance in Staphylococcus aureus. Future Microbiol. 2009;4(5):565-82. doi: 10.2217/fmb.09.30. PMID 19492967.
4. Small PM, Chambers HF. Vancomycin for Staphylococcus aureus endocarditis in intravenous drug users. Antimicrob Agents Chemother. 1990;34(6):1227-31. doi: 10.1128/aac.34.6.1227, PMID 2393284.
5. Diallo OO, Baron SA, Abat C, Colson P, Chaudet H, Rolain JM. Antibiotic resistance surveillance systems: a review. J Glob Antimicrob Resist. 2020;23:430-8. doi: 10.1016/j.jgar.2020.10.009 - DOI - PubMed. PMID 33176216.
6. Gu F, He W, Xiao S, Wang S, Li X, Zeng Q, Ni Y, Han L. Antimicrobial resistance and molecular epidemiology of Staphylococcus aureus causing bloodstream infections at RuiJin Hospital in shanghai from 2013 to 2018 [sci rep:6019]. Sci Rep. 2020; 10(1):6019. doi: 10.1038/s41598-020-63248-5.  PMC - PubMed. PMID 32265473.
7. Bauer AW. Single-Disk Antibiotic-Sensitivity Testing of Staphylococci. A.M.A. Arch Intern Med. 1959;104(2):208-16.
8. doi: 10.1001/archinte.1959.00270080034004.
9. Clinical and Laboratory Standards Institute. M100-S17. Performance standards for antimicrobial susceptibility testing; 16th informational supplement. Wayne, PA: Clinical and Laboratory Standards Institute; 2007.
10. John J. The treatment of resistant staphylococcal infections. F1000Research. 2020;9(F1000 Faculty Rev):150. doi: 10.12688/f1000research.17718.1, PMID 32148777. - DOI - PMC – PubMed.
11. Saeed, Aqib; Ahsan, Fatima; Nawaz, Muhammad; Iqbal, Khadeja; Rehman, Kashif U.; Ijaz, Tayyaba. 2020. "Incidence of Vancomycin Resistant Phenotype of the Methicillin Resistant Staphylococcus aureus Isolated fromaTertiaryCareHospitalinLahore" Antibiotics 9,no.1:3.https://doi.org/10.3390/antibiotics9010003
12. Hashemian S. M., Farhadi T., Ganjparvar M. (2018). Linezolid: a Review of its Properties, Function, and Use in Critical Care. Dddt Vol. 12, 1759–1767. 10.2147/dddt.s164515
13. Von Eiff C, Peters G. Comparative in-vitro activities of moxifloxacin, trovafloxacin, quinupristin/dalfopristin and linezolid against staphylococci. J Antimicrob Chemother. 1999;43(4):569-73. doi: 10.1093/jac/43.4.569, PMID 10350389.
14. Deep A, Goe N, Sikka R, Chaudhary U, Yadav S, Gupta A, Gill PS. Quinpristin-dalfopristin resistance in Gram-positive bacteria: experience from a tertiary care referral center in North India. J Infect Dis Antimicrob Agents. 2008;25:117-21.
15. Tünger A, Aydemir S, Uluer S, Cilli F. In vitro activity of linezolid & quinupristin/dalfopristin against Gram-positive cocci. Indian J Med Res. 2004;120(6):546-52. PMID 15654141.
16. Hafiz S, HafizAN AL, ChughtaiAS, Memon B, Ahmed A, Hussain S, Sarwar G, Mughal T, Siddiqui SJ, Awan A, Zaki K, Fareed A. Methicillin resistant Staphylococcus aureus: A multicentre study.J Pak Med Assoc.2002;52(7):312-5. PMID 12481663.
17. Tiwari HK, Sen MR. Emergence of vancomycin resistant Staphylococcus aureus (VRSA) from a tertiary care hospital from northern part of India. B.M.C. Infect Dis. 2006;6:156. doi: 10.1186/1471-2334-6-156, PMID 17067393.
18. Al-Baidani AR H, El-Shouny WA, Taha M. Shawa ”antibiotic Susceptibility pattern of MRSA in Three Hospitals at Al Hudaydah City, Yemen.” Glob J Pharmacol. 2011;5(2):106-11.
19. Bhatawadekar S, Chattopadhyay A. Quinpristin-Dalfopristin resistance among methicillin-resistant strains of staphylococci. Indian J Pharmacol. 2010;42(1):56. doi: 10.4103/0253-7613.62403, PMID 20606841
20. betriu C, Redondo M, Boloix A, Gómez M, Culebras E, Picazo JJ. Comparative activity of linezolid and other new agents against methicillin-resistant Staphylococcus aureus and teicoplanin-intermediate coagulase-negative staphylococci. J Antimicrob Chemother. 2001;48(6):911-3. doi: 10.1093/jac/48.6.911, PMID 11733478.
21. von Eiff C, Peters G. Comparative in-vitro activities of moxifloxacin, trovafloxacin, quinupristin/dalfopristin and linezolid against staphylococci. J Antimicrob Chemother. 1999;43(4):569-73. doi: 10.1093/jac/43.4.569, PMID 10350389