Indian Journal of Medical Microbiology Medknow Publications on behalf of Indian Association of Medical Microbiology ISSN: 0255-0857 EISSN: 1998-3646 Vol. 29, Num. 4, 2011, pp. 443-444

Indian Journal of Medical Microbiology, Vol. 29, No. 4, October-December, 2011, pp. 443-444

Correspondence

Omission of extended spectrum β lactamases detection: Are the new Clinical Laboratory Standards Institute guidelines misleading?

C Chande, S Makhija, S Lilani, R Shirpurkar, P Veer, A Chivate, P Patekar, A Joshi

Department of Microbiology, Grant Medical College and Sir J. J. Group of Hospitals, Mumbai 400 008, India
Correspondence Address: C Chande, Department of Microbiology, Grant Medical College and Sir J. J. Group of Hospitals, Mumbai 400 008, India, cachande@gmail.com

Date of Submission: 10-Mar-2011
Date of Acceptance: 01-Jul-2011

Code Number: mb11110

PMID: 22120816
DOI: 10.4103/0255-0857.90197

Dear Editor,

Emerging bacterial resistance is the most serious problem being faced in the clinical practice today. Antibiotic susceptibility testing (AST) is the most valuable tool at the disposal of microbiology laboratory to offer assistance to the clinicians to arrive at an appropriate therapeutic conclusion. Many laboratories engaged in AST are following the guidelines defined by the Clinical Laboratory Standards Institute (CLSI) for testing and interpretation of results. As per the latest (2010) guidelines of CLSI, ^[1] new interpretive criteria for cephalosporins including cefazolin, cefotaxime, ceftazidime, ceftizoxime ceftriaxone and aztreonam are suggested and extended spectrum β lactamase (ESBL) detection is no longer necessary to edit results for cephalosporins, aztreonam or penicillins to resistant. The bacteriology section of Microbiology department in the Grant Medical College and Sir J J Group of Hospitals, Mumbai, started implementing the new criteria since August 2010 but also continued ESBL testing as per the CLSI 2009 ^[2] guidelines. In the past six months we have observed that many strains of gram negative bacilli which are resistant to third generation cephalosporins have produced zones in the susceptible range for piperacillin. All these strains were also ESBL producers, hence as per 2009 criteria, fall in the category of resistant strains and should be reported as such. However with the new criteria, in the absence of ESBL testing, such strains might erroneously be reported as piperacillin sensitive. With such grossly fallacious conclusion being drawn, a detailed discussion at a proper forum is needed between the users of new CLSI criteria. Authors will feel highly obliged if the learned contributors of this esteemed journal express their opinion on the matter.

References

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