Sajjad Husain Mirza ( Department of Microbiology, Armed Forces Institute of Pathology,Rawalpindi. )
Umar Khurshid ( Department of Microbiology, Armed Forces Institute of Pathology,Rawalpindi. )
M. Amin Wiqar ( Department of Microbiology, Armed Forces Institute of Pathology,Rawalpindi. )
March 2006, Volume 56, Issue 3
Letter to the Editor
Madam, Two classes of ESBLs are normally prevalent. TEM and SHY types showing resistance to ceftazidime and variable resistance to cefotaxime and CTX-M types manifesting resistance to cefotaxime and variable resistance to ceftazidime. 1 Phenotypic cofirmatory tests therefore cater for this by advocating testing both the antibiotics. 2 The authors in the study tested only cefotaxime and its combination with clavulanic acid which is against the current recommendations of NCCLS. Secondly withdrawal of anyone of the antibiotics from the phenotypic confirmatory test renders the results doubtful because one class of ESBLs have not been evaluated at all. 3 The NCCLS recommendation of testing both antibiotics dates back to the year 2000. 4 We are not aware of the NCCLS recommendations of 1999 as cited in the study. No disclaimer has been notified that new recommendations are now in vogue. It is felt that clinical laboratories in the country may be misled by the perception carried from this study that only Cefotaxime and its combination with clavulanic acid needs to be tested for detecting ESBLs.
| References |
1. Pitout JD, Nordmann P, Laupland KB and Poire L. Emergence of Enterobacteriacae producing extended spectrum beta lactamases (ESBLs) in the community. Journal of Antimicrobial Chemotherapy .2005; 56:52-59.
2. Performance standards for antimicrobial susceptibility testing; Fourteenth Informational Supplement (M100-S14) 2004. Wayne PA National Committee for Clinical Laboratories.
3. Livermore DM, Hawkey PM. CTX-M: Changing the face of ESBLs in the UK. Journal of Antimicrobial Chemotherapy 2005; 56:451-54.
4. Performance standards for antimicrobial susceptibility testing; Seventh: Edition (M2-A7) 2000. Wayne PA National Committee for Clinical Laboratories.
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