Indan Journal of Medical Research Indan Journal of Medical Research Indan Journal of Medical Research Indan Journal of Medical Research
  Home About us Editorial board Search Ahead of print Current issue Archives Submit article Instructions Subscribe Contacts Login  
  Home Print this page Email this page Small font sizeDefault font sizeIncrease font size Users Online: 539       

   Table of Contents      
CORRESPONDENCE
Year : 2014  |  Volume : 139  |  Issue : 4  |  Page : 646

Susceptibility testing of Staphylococaus aureus


Department of Microbiology, Amrita Institute of Medical Sciences Ponekara, Kochi, Kerala, 682 041, India

Date of Web Publication9-Jun-2014

Correspondence Address:
V. Anil Kumar
Department of Microbiology, Amrita Institute of Medical Sciences Ponekara, Kochi, Kerala, 682 041
India
Login to access the Email id

Source of Support: None, Conflict of Interest: None


PMID: 24927355

Rights and PermissionsRights and Permissions

How to cite this article:
Kumar VA. Susceptibility testing of Staphylococaus aureus. Indian J Med Res 2014;139:646

How to cite this URL:
Kumar VA. Susceptibility testing of Staphylococaus aureus. Indian J Med Res [serial online] 2014 [cited 2019 Jun 26];139:646. Available from: http://www.ijmr.org.in/text.asp?2014/139/4/646/134141

Sir,

Chitnis et al [1] have done an excellent job of determining the MIC of daptomycin, linezolid and teicoplanin in  S.aureus Scientific Name Search  and Enterococcus faecalis but they did not interpret the sensitivity results properly, as given below:

(i)0 Oxacillin disc diffusion (DD) has a sensitivity of only 91 per cent and specificity of only 58.9 per cent while cefoxitin DD has sensitivity and specificity of 97.8 & 100 per cent, respectively [2] . Therefore, oxacillin DD could not have given a result identical to cefoxitin DD.

(ii) Though the authors have reported the susceptibility of erythromycin and clindamycin, but they did not make an effort to detect inducible resistance to clindamycin which has got immense clinical significance.

(iii) The table shows that resistance to ampicillin was 67.67 per cent while MRSA rate was 73.33 per cent which implies that almost 5 per cent of the MRSA isolates were actually sensitive to ampicillin [1] . The authors seem to have committed an error in susceptibility test reporting.

(iv) For MRSA there is no need to test and report beta-lactams (Table 1) as these all are considered resistant irrespective of their zone diameters.

(v) CLSI has done away with vancomycin DD and recommends only MIC testing [3] . Therefore, the data presented in Table on vancomycin susceptibility based on DD are not valid.

(vi) High level aminoglycoside (gentamicin 120 µg) needs to be tested for enterococci to determine its synergy with ampicillin/penicillin/vancomycin. The authors have tested 10 µg instead [3] .

(vii) According to CLSI (2009) the vancomycin MIC for susceptible is ≤ 2 µg/ml, intermediate is 4-8 µg/ml and resistant is ≥ 16 µg/ml. The authors have reported 16 MRSA isolates with MIC of 3µg/ml and classified these as sensitive [3] .

 
   References Top

1.Chitnis S, Katara G, Hemvani N, Pareek S, Chitnis DS. In vitro activity of daptomycin & linezolid against methicillin resistant Staphylococcus aureus & vancomycin resistant enterococci isolated from hospitalized cases in Central India. Indian J Med Res 2013; 137 : 191-6.  Back to cited text no. 1
[PUBMED]  Medknow Journal  
2.Swenson JM, Lonsway D, McAllister S, Thompson A, Jevitt L, Zhu W, et al. Detection of mecA-mediated resistance using reference and commercial testing methods in a collection of Staphylococcus aureus expressing borderline oxacillin MICs. Diagn Microbiol Infect Dis 2007; 58 : 33-9.   Back to cited text no. 2
    
3.Clinical and Laboratory Standards Institute. Performance standards for antimicrobial susceptibility testing; 19 th informational supplement. CLSI document M100-S19. Wayne, PA: Clinical and Laboratory Standards Institute; 2009.  Back to cited text no. 3
    




 

Top
 
 
  Search
 
    Similar in PUBMED
   Search Pubmed for
   Search in Google Scholar for
    Access Statistics
    Email Alert *
    Add to My List *
* Registration required (free)  

 
  In this article
    References

 Article Access Statistics
    Viewed313    
    Printed8    
    Emailed0    
    PDF Downloaded232    
    Comments [Add]    

Recommend this journal