Detection of vancomycin susceptibility among clinical isolates of MRSA by using minimum inhibitory concentration method

Authors

  • P. Sreenivasulu Reddy Department of Microbiology, Narayana Medical College, Nellore, Andhra Pradesh
  • Maria Sindhura John Department of Microbiology, Narayana Medical College, Nellore, Andhra Pradesh
  • P. Vasundhara Devi Department of Microbiology, Narayana Medical College, Nellore, Andhra Pradesh
  • B. Siva Prasad Reddy Department of Microbiology, Narayana Medical College, Nellore, Andhra Pradesh

DOI:

https://doi.org/10.18203/2320-6012.ijrms20150151

Keywords:

MRSA, VSSA, VISA, VRSA, MIC

Abstract

Background: Staphylococcus aureus is considered as a major pathogen causing a diversity of infections including bacteremia, pneumonia, skin and soft tissue including osteoarticular infections. Since 1961, Methicillin Resistant Staphylococci aureus (MRSA) emerged has one of the major and common cause of hospital acquired infection. However, due to wide spread usage of vancomycin for MRSA infections resulted in reduced susceptibility of S. aureus to vancomycin has been identified as a serious public health concern. The aim of the study is to identify the Methicillin Resistant Staphylococcus aureus (MRSA) from various clinical samples and to detect vancomycin susceptibility by Minimum Inhibitory Concentration (MIC) method.

Methods: This study was conducted over period of one year December 2013 to November 2014. Clinical samples like pus, blood, sputum, urine and cerebrospinal fluid were collected from various clinical departments in Narayana General Hospital for selective isolation of Staphylococcus aureus. A total of 100 Staphylococcal aureus isolates were isolatedby using standard laboratory procedures. MRSA were detected using Oxacillin Disc on Muller Hinton Agar with 4% NaCl. Sensitivity pattern for vancomycin (30 µg) disc and for other recommended antibiotics was determined by Kirby-Bauer’s disk diffusion method. Minimum Inhibitory Concentration (MIC) was done for vancomycin sensitive isolates by standard agar dilution method.

Results: Out of 100 S. aureus isolates, all were susceptible to vancomycin (30 µg) by disk diffusion method. But, 82 isolates of MRSA were susceptible to vancomycin at the concentration of 0.5-2 μg/ml of agar. 17 isolates showed intermediate sensitivity to vancomycin, in which 13 isolates with MIC 4μg/ml and 4 isolates with MIC 8 μg/ml and one isolate was resistant to vancomycin even with MIC of 16 μg/ml.

Conclusions: The present study reveals the emergence of Vancomycin Intermediate Sensitive Staphylococcus aureus (VISA) and Vancomycin Resistant Staphylococcus aureus (VRSA). Disc diffusion method should not be employed for detection of vancomycin sensitivity for MRSA stains. The major cause may be attributed to unawareness and irrational usage of broad spectrum antibiotics.

 

References

Denis O, Nonhoff C, Byl B, Knoop C, Bobin-Dubreux S, Struelens MJ. Emergence of vancomycin intermediate staphylococcus aureus in a Belgian hospital: Microbiological and clinical features. J Antimicrob Chemother. 2002;50:383-91.

National Nosocomial Infections Surveillance (NNIS). System report, data summary from January 1990 - May 1999. Am J Infect Control. 1999 June;277:520-32.

Waldvogel FA. Staphylococcus aureus. In: Mandell GL, Bennett JE, Dolin R, eds. Principles and Practice of Infectious Diseases. 5th ed. Philadelphia: Churchill Living Stone; 2000: 2069-2092.

Vidhani S, Mehndiratta PL, Mathur MD. Study of Methicillin resistant Staphylococcus aureus isolates from high risk patients. Indian J Med Microbiol. 2001;19:87-90

Smith TL, Pearson ML, Wilcox KR, Cruz C, Lancaster MV, Robinson-Dunn B, et al. Emergence of vancomycin resistance in Staphylococcus aureus. N Engl J Med. 1999;340:493-501.

Chaudary, Anupama. Prevalence of methicillin resistance in Staphylococcus aureus. Indian J Med Microbiol. 1999;17(3):154-5.

Thompson RL, Cabezudo I, Wenzel RP. Epidemiology of nosocomial infections caused by methicillin resistant Staphylococcus aureus. Ann Intern Med. 1982;97:309-17.

Rosenberg J. MRSA in community: WHO’s watching. Lancet. 1995;346:132-3.

Appelbaum PC. Reduced glycopeptides susceptibility in Methicillin resistant Staphylococcus aureus. Int J Antimicrob Agents. 2007;30(5):398-408.

Siddiqi F, Masood MB, Saba N, Samad A, Qayyum M, Qazilbash AA. Antibiogram sensitivity pattern of methicillin resistant Staphylococcus aureus isolates from pus samples. Pak J Biol Sci. 2002;5(4):491-3.

Kakru DK, Assadullah S, Thiker MA, Wani T. Methicillin resistant staphylococcus aureus: need for constant surveillance, stringent control and vigorous treatment measures. Indian J Pathol Microbiol. 2003;46(1):121-3.

Hanumanthappa AR, Chandrappa MR, Rajshekarappa MG. Prevalence of methicillin resistant Staphylococcus aureus in osteomyelitis. Indian J Pathol Microbiol. 2003;46(1):129-30.

Marchese A, Balisteri G, Tonoli, Debbia A, Schito G. Heterogenous vancomycin resistance in methicillin resistance S. aureus strains isolate in a large Italian hospital. J Clin Microbiol. 2000;38(2):866-9.

Assadullah S, Kakru DK, Thoker MA, Bhat FA, Hussain N, Shah A. Emergence of low level vancomycin resistance in MRSA. Indian J Med Microbiol. 2003;21(3):196-8.

Hakim ST, Arshad S, Iqbal M, Javid SG. Vancomycin sensitivity of staphylococcus aureus isolates from hospital in Karachi, Pakistan. Libyan J Med. 2007;2(4):176-9.

Chaudhari CN, Tandel K, Grover N, Bhatt P, Sahni AK, Sen S, et al. In vitro vancomycin susceptibility amongst methicillin resistant Staphylococcus aureus. Med J Armed Forces India. 2014 Jul;70(3):215-9.

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Published

2017-01-09

How to Cite

Reddy, P. S., John, M. S., Devi, P. V., & Reddy, B. S. P. (2017). Detection of vancomycin susceptibility among clinical isolates of MRSA by using minimum inhibitory concentration method. International Journal of Research in Medical Sciences, 3(6), 1378–1382. https://doi.org/10.18203/2320-6012.ijrms20150151

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Original Research Articles