Indian Journal of Medical Microbiology Medknow Publications on behalf of Indian Association of Medical Microbiology ISSN: 0255-0857 EISSN: 1998-3646 Vol. 29, Num. 3, 2011, pp. 314-315

Indian Journal of Medical Microbiology, Vol. 29, No. 3, July-September, 2011, pp. 314-315

Correspondence

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
Correspondence Address: U Kalawat, Department of Microbiology, Sri Venkateswara Institute of Medical Sciences, Tirupati, Andhra Pradesh - 517 507, India, ukalawat@yahoo.com

Date of Submission: 25-Apr-2011 
Date of Acceptance: 01-Jul-2011

Code Number: mb11077

PMID: 21860120

DOI: 10.4103/0255-0857.83923

Dear Editor,

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.^[1] Linezolid appears to work on the first step of protein synthesis initiation. ^[2] 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. ^[3]

The first case linezolid-resistant staphylococci appeared within 1 year after linezolid was approved for use for treatment. ^[4] From India, first case report of linezolid resistance was published in 2011 from cases of sepsis from Kashmir in this journal. ^[5] 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].

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

1.	Jones RN, Fritsche TR, Sader HS, Ross JE. LEADER Surveillance program results for 2006: An activity and spectrum analysis of linezolid using clinical isolates from the United States (50 medical centers). Diagn Microbiol Infect Dis 2007;59:309-17.  Back to cited text no. 1  [PUBMED]  [FULLTEXT]
2.	Swaney SM, Aoki H, Ganoza MC, Shinabarger DL. "The oxazolidinone linezolid inhibits initiation of protein synthesis in bacteria". Antimicrob Agents Chemother 1998;12:3251-5.   Back to cited text no. 2
3.	Zurenko GE, Yagi BH, Schaadt RD, Allison JW, Kilburn JO, Glickman SE, et al. In vitro activities of U-100592 and U-100766, novel oxazolidinone antibacterial agents. Antimicrob Agents Chemother1996;40:839-45.  Back to cited text no. 3  [PUBMED]  [FULLTEXT]
4.	Tsiodras S, Gold HS, Sakoulas G, Eliopoulos GM, Wennersten C, Venkataraman L, et al. Linezolid resistance in a clinical isolate of Staphylococcus aureus. Lancet 2001;358:207-8.  Back to cited text no. 4  [PUBMED]  [FULLTEXT]
5.	Peer MA, Nasir RA, Kakru DK, Fomda BA, Bashir G, Sheikh IA. Sepsis due to linezolid resistant Staphylococcus cohnii and Staphylococcus kloosii: First reports of linezolid resistance in coagulase negative staphylococci from India. Indian J Med Microbiol 2011;29:60-2.  Back to cited text no. 5  [PUBMED]

Copyright 2011 - Indian Journal of Medical Microbiology

The following images related to this document are available:

Photo images