Indian Journal of Medical Microbiology Medknow Publications on behalf of Indian Association of Medical Microbiology ISSN: 0255-0857 EISSN: 1998-3646 Vol. 26, Num. 4, 2008, pp. 398-398

Indian Journal of Medical Microbiology, Vol. 26, No. 4, October-December, 2008, pp. 398

Correspondence

Imipenem resistant metallo β lactamse producing Pseudomonas aeruginosa

Chacko B, Varaiya A, Dedhia B

Department of Microbiology, Dr. L.H. Hiranandani Hospital, Powai, Mumbai - 400 076, Maharashtra
Correspondence Address:Department of Microbiology, Dr. L.H. Hiranandani Hospital, Powai, Mumbai - 400 076, Maharashtra
amivaraiya@yahoo.com

Date of Submission: 09-Jan-2008
Date of Acceptance: 01-Feb-2008

Code Number: mb08124

Dear Editor,

Pseudomonas aeruginosa, an important nosocomial pathogen is difficult to treat because of high antimicrobial resistance. ^[1] The common form of resistance is mediated by lack of drug penetration and / or carbapenem hydrolyzing β-lactamases. ^[2] Detection of metallo β lactamase (MBL)-producing P. aeruginosa is crucial for the optimal treatment of patients. The present study was undertaken to study Imipenem resistant P. aeruginosa for MBL production.

Seventy six Pseudomonas aeruginosa isolates were obtained from various types of specimens (38 respiratory secretions, 10 body fluids, 10 pus swabs, 8 catheter tips, 5 catheterized urine samples and 5 - blood culture) over a one year period from October 2006 to September 2007. Isolates were identified by standard laboratory techniques and antibiotic sensitivity was performed on Mueller Hinton Agar plates by Kirby Bauer disc diffusion method using commercially available discs (Hi Media) according to CLSI guidelines. ^[3] Disc approximation test was used to detect MBL production - the zone size difference between imipenem alone and imipenem+EDTA being ≥ 7 mm. P. aeruginosa ATCC 27853 was used as a negative control.

In this study 11 out of 76 (14.47%) strains were resistant to imipenem. Of these 11 strains, 8 (10.53%) were found positive for MBL production. Strains producing metallo beta lactamase were 100% sensitive to colistin, 81% to piperacillin/ tazobactam and 54% to gatifloxacin. Thus, MBL production was observed in multiresistant P. aeruginosa which were imipenem resistant.

EDTA impregnated imipenem discs can be easily used and are inexpensive for primary screening for multi drug resistant P. aeruginosa isolates. Sensitivity to Colistin represents the best treatment option for metallo betalactamase producing P. aeruginosa .

References

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