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Indian Journal of Medical Microbiology
Medknow Publications on behalf of Indian Association of Medical Microbiology
ISSN: 0255-0857 EISSN: 1998-3646
Vol. 28, Num. 4, 2010, pp. 370-371

Indian Journal of Medical Microbiology, Vol. 28, No. 4, October-December, 2010, pp. 370-371

Brief Communication

The effect of tigecycline and ertapenem against clinical isolates of Brucella melitensis detected by E-test on different media

E Tanyel1, AY Coban2, N Tasdelen Fisgin1, N Tulek1

1 Department of Clinical Microbiology and Infectious Diseases, Ondokuz Mayis University, Medical School, Samsun, Turkey
2 Department of Microbiology and Clinical Microbiology, Ondokuz Mayis University, Medical School, Samsun, Turkey
Correspondence Address:
E Tanyel, Department of Clinical Microbiology and Infectious Diseases, Ondokuz Mayis University, Medical School, Samsun, Turkey, estanyel@yahoo.com.tr

Date of Submission: 21-Dec-2009
Date of Acceptance: 01-Jul-2010

Code Number: mb10108

PMID: 20966572
DOI: 10.4103/0255-0857.71822

Abstract

In this study, in vitro activity of tigecycline (TIG) and ertapenem (ERT) against clinical isolates of Brucella melitensis and the effect of different media on in vitro test results were investigated. The in vitro effects of TIG and ERT to 38 B. melitensis isolates were comparatively investigated in brucella agar and 5% sheep blood agar. MIC value of ERT was 0.032 μg/mL in 23 of 38 and 20 of 38 isolates on blood and brucella agar, respectively. Minimum inhibitory concentration values of TIG were substantially different ranging between 0.064-0.25 μg/mL on blood agar. However, MIC values of TIG were similar on brucella agar with 0.25 μg/mL in 15 of 38 isolates and 0.5 μg/mL in 10 of 38 isolates. In conclusion, although ERT and TIG were effective against B. melitensis isolates in vitro, further studies are needed in order to determine the use of these novel drugs in treatment of brucellosis.

Keywords: Brucellosis, tigecycline, ertapenem

Introduction

Brucellosis is a disease that is widely seen especially in the developing countries. Because active microorganism is located inside the cell, it is difficult to treat this disease; combined and long-term antibiotic treatment must be applied. In addition, the drugs that are used should be transferred into the cells successfully and keep their effectiveness in this acidic environment. [1] Ertapenem (ERT), which is a new antibiotic in our country is a synthetic, long-term effective carbapenem that can be intravenously and intramuscularly applied once a day. Tigecycline (TIG) is a synthetic derivation of minocycline of glycylcycline class. [2],[3] The glycylcyclines inhibits bacterial protein synthesis by binding ribosomal A zones five times stronger than tetracyclines. In this study, we aimed to investigate the effects of ERT and TIG against Brucella melitensis isolates.

The susceptibilities to TIG and ERT were determined by using E-test (AB Biodisk, Solna, Sweden) method on 5% sheep blood agar (bioMθrieoux SA, Marcy I'Etoile, France) and Brucella agar (Oxoid Ltd., Basingstoke, Hampshire, England) against B. melitensis 38 clinical isolates. The minimum inhibitory concentrations (MICs) of TIG and ERT for all isolates on two blood agar media is summarized in [Table - 1]. The MIC values of ERT and TIG were showing differences depending on two blood agar media but there was a marked difference for TIG, and MICs of TIG were higher in brucella agar.

In the in vitro studies that were conducted in order to find the effectiveness of TIG in the brucella strains; it was thought that TIG could be an alternative agent.[4] Dizbay et al. [5] found that TIG had the lowest values in MIC 50 (0.064 μg/ml) and MIC 90 (0.094 μg/ml) against B. melitensis 16 isolates. In addition, Kilic et al. [6] determined that TIG had the second lowest level of MIC 90 (0.125 μg/ml) after levofloxacin, and could be an alternative agent in the treatment of brucellosis. Turan et al. [7] noted that the MIC 90 value of TIG as 0.125 μg/ml was lower than the MIC values that of rifampin and ciprofloxacin. In our study, MIC 90 value of TIG was found to be 0.38 and 1 μg/ml for blood and brucella agar, respectively. In PUBMED scanning, no study about the effectiveness of ERT to the brucella strains was found. MIC 90 value of ERT was found to be 0.047 and 0.064 μg/ml for blood and brucella agar, respectively, in this study.

The CLSI recommends brucella broth whose pH was adjusted to 7.1 ± 0.1 for susceptibility testing. [8] Therefore, in our study, we used brucella and blood agar media, and we observed that brucella agar is enough for bacterial reproduction. The variability in the results of the conducted studies may be due to the use of different media. In this study, we detected that MIC values were changing according to the media especially for TIG. As a result, it was proved that ERT and TIG are in vitro effective against the B. melitensis isolates. This is the first in vitro study that shows effectiveness of ERT on the brucella strains. There may be alternative drugs in the treatment but in vivo studies are needed in order to use these drugs in treatment of the disease.

References

1.Young EJ. Brucella species, Section F, Chapter 226. In: Mandell GL, Bennett JE, Dolin R, editors. Mandell, Douglas, Bennett's Principles and Practice of Infectious Disease. 7 th ed. Philadelphia: Churchill Livingstone Elsevier; 2010. p. 2921-5.  Back to cited text no. 1    
2.Lee SC, Huang SS, Lee CW, Fung CP, Lee N, Shieh WB, et al. Comparative antimicrobial susceptibility of aerobic and facultative bacteria from community-acquired bacteremia to ertapenem in Taiwan. BMC Infect Dis 2007;7:79.   Back to cited text no. 2  [PUBMED]  [FULLTEXT]
3.Zhanel GG, Johanson C, Embil JM, Noreddin A, Gin A, Vercaigne L, et al. Ertapenem: Review of a new carbapenem. Expert Rev Anti Infect Ther 2005;3:23-39.   Back to cited text no. 3  [PUBMED]  
4.Pappas G, Solera J, Akritidis N, Tsianos E. New approaches to the antibiotic treatment of brucellosis. Int J Antimicrob Agents 2005;26:101-5.  Back to cited text no. 4  [PUBMED]  [FULLTEXT]
5.Dizbay M, Kilic S, Hizel K, Arman D. Tigecycline: Its potential for treatment of brucellosis. Scand J Infect Dis 2007;39:432-4.  Back to cited text no. 5  [PUBMED]  [FULLTEXT]
6.Kilic S, Dizbay M, Cabadak H. In vitro activity of tigecycline, tetracycline and fluoroquinolones against Brucella melitensis. J Chemother 2008;20:33-7.  Back to cited text no. 6  [PUBMED]  [FULLTEXT]
7.Turan H, Arslan H, Azap OK, Serefhanoπlu K, Uncu H. In vitro antibacterial activity of tigecycline in comparison with doxycycline, ciprofloxacin and rifampicin against Brucella spp. Int J Antimicrob Agents 2007;30:186-7.   Back to cited text no. 7    
8.Clinical and Laboratory Standards Institute, Performance standards for antimicrobial susceptibility testing. January 28, 2008. p. 1.  Back to cited text no. 8    

Copyright 2010 - Indian Journal of Medical Microbiology

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