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Year : 2010  |  Volume : 28  |  Issue : 4  |  Page : 413--414

Increasing levels of minimum inhibitory concentration vancomycin in methicillin resistant Staphylococcus aureus alarming bell for vancomycin abusers?

P Veer, C Chande, S Chavan, V Wabale, K Chopdekar, J Bade, A Joshi 
 Department of Microbiology, Grant Medical College & Sir J. J. Group of Hospitals, Byculla, Mumbai 400 008, India

Correspondence Address:
C Chande
Department of Microbiology, Grant Medical College & Sir J. J. Group of Hospitals, Byculla, Mumbai 400 008
India

How to cite this article:
Veer P, Chande C, Chavan S, Wabale V, Chopdekar K, Bade J, Joshi A. Increasing levels of minimum inhibitory concentration vancomycin in methicillin resistant Staphylococcus aureus alarming bell for vancomycin abusers?.Indian J Med Microbiol 2010;28:413-414

How to cite this URL:
Veer P, Chande C, Chavan S, Wabale V, Chopdekar K, Bade J, Joshi A. Increasing levels of minimum inhibitory concentration vancomycin in methicillin resistant Staphylococcus aureus alarming bell for vancomycin abusers?. Indian J Med Microbiol [serial online] 2010 [cited 2019 Oct 15 ];28:413-414
Available from: http://www.ijmm.org/text.asp?2010/28/4/413/71810

Full Text

Dear Editor,

Increasing minimum inhibitory concentration of an antimicrobial for a bacterium is the marker of future resistance of the organism to that antibiotic. [1] Vancomycin is the drug of choice for the infections caused by methicillin resistant Staphylococcus aureus (MRSA) and often used empirically for the patients in critical-care settings with infections like severe sepsis, pneumonias and those under umbilical catheterization etc in India. The presence of vancomycin pressure is likely to increase the selection of resistant strains. Recovery of clinical isolates of vancomycin resistant S. aureus from outside India is reported. [2],[3] Emergence of low level vancomycin resistance has already been reported from India. [4] Continuous surveillance is therefore required to monitor the emergence of vancomycin -intermediate Staphylococcus aureus (VISA) and vancomycin resistant Staphylococcus aureus (VRSA) strains. When the susceptibility levels for vancomycin in MRSA strains (identified using 30 μg cefoxitin discs) that were recovered during January 2008 to June 2009 was assessed, [5] it was observed that in 77 isolates recovered from blood and pus specimens, as many as 31 (40.25%) isolates had MIC 4μg/ml by agar dilution method. As per the Clinical and Laboratory Standard Institute (CLSI) guidelines of 2008, strains with MIC of 4 to 8 μg/ml should be categorized as VISA strains. None of these isolates grew on vancomycin screen brain heart infusion agar plate with vancomycin 6 μg/ml. All the isolates were sensitive to vancomycin by disc diffusion test using 30μg vancomycin disc. Though none of the isolates had MIC ≥16 μg/ml, the high level of MIC in the sensitive strains is definitely alarming considering the therapeutic consequences of vancomycin resistance in S. aureus. The strains showed 100% sensitivity to linezolid and rifampicin and 31% and 35% susceptibility to cotrimoxazole and clindamycin respectively. The increasing MICs of S. aureus isolates to vancomycin are an alarming bell for the users as the strains with reduced susceptibility could be the harbinger of future strains with full-blown resistance. In view of the limited therapeutic options for the treatment of MRSA infections, prudent use of vancomycin, continuous surveillance for VISA and VRSA strains and appropriate infection control practices for the prevention of spread of such strains in the hospital environment are strongly recommended.

References

1Levy SB. Multidrug resistance-a sign of the times. N Engl J Med 1998;338:1376-8.
2Smith TL, Pearson ML, Wilcox KR, Cruz C, Lancaster MV, Robinson-Dunn B, et al. Emergence of vancomycin resistance in Staphylococcus aureus. N Eng J Med 1999;340:493-501.
3Chang S, Sievert DM, Hageman JC, Boulton ML, Tenover FC, Downes FP, et al. Infection with Vancomycin-Resistant Staphylococcus aureus containing the vanA resistance gene. N Eng J Med 2003;348:1342-7.
4Assadullah S, Kakru DK, Thoker MA, Bhat FA, Hussain N, Shah A. Emergence of low level Vancomycin resistance in MRSA. Indian J Med Microbiol 2009;21:196-8.
5Clinical and Laboratory Standard Institute (CLSI): Performance standards for antimicrobial susceptibility testing. 18 th International Supplement. CLSI document M 100-18, Wayne, Pennsylvania, 2008.