|Year : 2011 | Volume
| Issue : 3 | Page : 314-315
Linezolid-resistant Staphylococcus spp. at a tertiary care hospital of Andhra Pradesh
U Kalawat, KK Sharma, S Reddy
Department of Microbiology, Sri Venkateswara Institute of Medical Sciences, Tirupati, Andhra Pradesh - 517 507, India
|Date of Submission||25-Apr-2011|
|Date of Acceptance||01-Jul-2011|
|Date of Web Publication||17-Aug-2011|
Department of Microbiology, Sri Venkateswara Institute of Medical Sciences, Tirupati, Andhra Pradesh - 517 507
|How to cite this article:|
Kalawat U, Sharma K K, Reddy S. Linezolid-resistant Staphylococcus spp. at a tertiary care hospital of Andhra Pradesh. Indian J Med Microbiol 2011;29:314-5
|How to cite this URL:|
Kalawat U, Sharma K K, Reddy S. Linezolid-resistant Staphylococcus spp. at a tertiary care hospital of Andhra Pradesh. Indian J Med Microbiol [serial online] 2011 [cited 2015 Jan 26];29:314-5. Available from: http://www.ijmm.org/text.asp?2011/29/3/314/83923
Linezolid is a oxalidinone antibiotic which is used to treat infections caused by multidrug-resistant gram-positive cocci such as vancomycin-resistant Enterococcus faecium, Staphylococcus epidermidis, and methicillin-resistant Staphylococcus aureus. Linezolid appears to work on the first step of protein synthesis initiation.  Because linezolid is a purely synthetic antimicrobial, it was thought that preexisting mechanisms of resistance to linezolid would not be common in nature and, thus, that resistance would be slow to emerge. 
The first case linezolid-resistant staphylococci appeared within 1 year after linezolid was approved for use for treatment.  From India, first case report of linezolid resistance was published in 2011 from cases of sepsis from Kashmir in this journal.  Here we report two linezolid-resistant coagulase negative staphylococcal strains which were isolated in June 2010 at our hospital.
Catheter tips were inoculated on blood agar and MacConkey agar by roll pate method. Culture plates were incubated overnight at 37°c. Gram stain, catalase test and slide, as well as tube coagulase tests were performed as per standard procedures.
Antibiotic sensitivity was done by Kirby-Bauer disk diffusion method, and minimum inhibitory concentration (MIC) for linezolid was performed using Hi-Combi strips (High Media) as per manufacturer's instructions. Speciation of the isolates was done by sugar fermentation, amino acid decarboxylation, and disk sensitivity testing (PolymixinB and Bacitracin). Controls were set up for all the tests. The isolates were identified as Staphylococcus hominis and Staphylococcus lugdunensis. MICs of linezolid for the two isolates were more than 250 μg/ml [Figure 1] and an isolate sensitive to linezolid is shown in [Figure 2]. Sensitivity to other drugs is shown in [Table 1].
|Figure 1: Linezolid-resistant isolate with MIC >250 ƒÊg/ml HiComb TM MIC TEST strip|
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As suggested by prior reports, the resistance in our patients may have been acquired following the prior linezolid exposure. Because ours is a tertiary care hospital, so it is most likely that patients may have taken the drug before coming to our institute. We need to review the antibiotic policy of our hospital and keep the life-saving drugs reserved as the final resort, otherwise these sporadic cases of resistance may become more frequent and result in outbreak of multidrug-resistant infection in the hospital and may spread to community as well.
| ~ References|| |
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[Figure 1], [Figure 2]
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