This Article
Right arrow Full Text (PDF)
Right arrow Alert me when this article is cited
Right arrow Alert me if a correction is posted
Services
Right arrow Similar articles in this journal
Right arrow Similar articles in PubMed
Right arrow Alert me to new issues of the journal
Right arrow Download to citation manager
Right arrowReprints and Permissions
Right arrow Copyright Information
Right arrow Books from ASM Press
Right arrow MicrobeWorld
Citing Articles
Right arrow Citing Articles via HighWire
Right arrow Citing Articles via Google Scholar
Google Scholar
Right arrow Articles by Hui, M.
Right arrow Articles by Chan, C. Y.
Right arrow Search for Related Content
PubMed
Right arrow PubMed Citation
Right arrow Articles by Hui, M.
Right arrow Articles by Chan, C. Y.

 Previous Article  |  Next Article 

Journal of Clinical Microbiology, April 2008, p. 1573, Vol. 46, No. 4
0095-1137/08/$08.00+0     doi:10.1128/JCM.02420-07
Copyright © 2008, American Society for Microbiology. All Rights Reserved.

LETTER TO THE EDITOR

Endophthalmitis: Potential Benefits of Repeated Intravitreal Injections of Antibiotics


arrow
LETTER
 
We read with great interest the report by Chen et al. (3) describing a case of Burkholderia pseudomallei bacteremia and endophthalmitis successfully treated with ceftazidime.

Infective endophthalmitis is a sight-threatening emergency. Intravitreal injection of vancomycin together with ceftazidime is a commonly prescribed empirical choice. However, precipitates can be formed by these two antibiotics (6). We had previously reported that such precipitate can reduce the free drug concentration of ceftazidime to as low as 6.3 µg/ml in vitreous after 48 h when prepared in balanced salt solution (5). This raises a concern, since MICs of many nonfermenters are approaching such levels. In fact, the ceftazidime MIC90 of Burkholderia pseudomallei had been reported to range from 4 µg/ml to 32 µg/ml, depending on the assay methods being employed (4).

Ceftazidime, as a beta-lactam, does not exhibit a significant postantibiotic effect. Its antibacterial activity is more dependent on the duration of its concentration being above the MIC levels. Thus, in the event of Burkholderia pseudomallei septicemia, continuous infusion had been advocated to maintain the target concentration in serum (1). On the other hand, the ocular pharmacokinetics is unique due to the presence of the blood-ocular barrier (2). Only a small proportion of parenterally administered drug can pass through the blood-retina barrier. Therefore, the treatment of infective endophthalmitis generally employs an empirical approach with intravitreal antibiotics, followed by careful clinical monitoring. The decision to repeat intravitreal injections often depends on the subjective assessment of the clinical response, microbiological results, and toxicity of the drugs to be given. Many times, only a single injection was given, which may contribute to lower cure rates (7).

In the report by Chen et al., the isolate demonstrated a ceftazidime MIC of 2 µg/ml. Although this is still within the susceptible range, it is prudent to maintain an adequate concentration of intravitreal antibiotic. However, the presence of vancomycin-ceftazidime precipitates may compromise the concentration of free drug. In the absence of a specific delivery method, such as an implant, repeated intravitreal injections for 3 days are probably the key to successful treatment in this case, even if the vitreous is culture negative. Therefore, systematic clinical studies to delineate the potential benefits of repeated intravitreal injections in endophthalmitis are warranted.


arrow
FOOTNOTES
 
Ed. Note: The authors of the published article did not reply.


arrow
REFERENCES
 
    1
  1. Angus, B. J., M. D. Smith, Y. Suputtamongkol, H. Mattie, A. L. Walsh, V. Wuthiekanun, W. Chaowagul, and N. J. White. 2000. Pharmacokinetic-pharmacodynamic evaluation of ceftazidime continuous infusion vs intermittent bolus injection in septicaemic meliodosis. Br. J. Clin. Pharmacol. 49:445-452.[CrossRef][Medline]
    2. 2
  2. Arto, U. 2006. Challenges and obstacles of ocular pharmacokinetics and drug delivery. Adv. Drug Deliv. Rev. 58:1131-1135.[CrossRef][Medline]
    3. 3
  3. Chen, K. J., M. H. Sun, C. H. Hou, C. C. Sun, and T. L. Chen. 2007. Burkholderia pseudomallei endophthalmitis. J. Clin. Microbiol. 45:4073-4074.[Abstract/Free Full Text]
    4. 4
  4. Inglis, T. J., F. Rodrigues, P. Rigby, R. Norton, and B. J. Currie. 2004. Comparison of the susceptibilities of Burkholderia pseudomallei to meropenem and ceftazidime by conventional and intracellular methods. Antimicrob. Agents Chemother. 48:2999-3005.[Abstract/Free Full Text]
    5. 5
  5. Kwok, A. K., M. Hui, C. P. Pang, R. C. Chan, S. W. Cheung, C. M. Yip, D. S. Lam, and A. F. Cheng. 2002. An in vitro study of ceftazidime and vancomycin concentrations in various fluid media: implications for use in treating endophthalmitis. Investig. Ophthalmol. Vis. Sci. 43:1182-1188.[Abstract/Free Full Text]
    6. 6
  6. Lifshitz, T., R. Lapid-Gortzak, Y. Finkelman, and I. Klemperer. 2000. Vancomycin and ceftazidime incompatibility upon intravitreal injection. Br. J. Ophthalmol. 84:117-118.[Free Full Text]
    7. 7
  7. Stern, G. A., H. M. Engel, and W. T. Driebe, Jr. 1989. The treatment of postoperative endophthalmitis. Results of differing approaches to treatment. Ophthalmology 96:62-67.[Medline]
M. Hui*
W. H. Lam
W. H. Ho
C. Y. Chan
Department of Microbiology
The Chinese University of Hong Kong
The Prince of Wales Hospital
Hong Kong SAR

* Phone: 852-2632 3333 Fax: 852-2647 3227 E-mail: mamiehui{at}cuhk.edu.hk

Journal of Clinical Microbiology, April 2008, p. 1573, Vol. 46, No. 4
0095-1137/08/$08.00+0     doi:10.1128/JCM.02420-07
Copyright © 2008, American Society for Microbiology. All Rights Reserved.



This article has been cited by other articles:

  • Chen, K.-J., Chen, T.-L., Lai, C.-C., Sun, M.-H. (2008). Endophthalmitis: Antibacterial Activity of Precipitates of Vancomycin and Ceftazidime. J. Clin. Microbiol. 46: 2149-2149 [Full Text]  

This Article
Right arrow Full Text (PDF)
Right arrow Alert me when this article is cited
Right arrow Alert me if a correction is posted
Services
Right arrow Similar articles in this journal
Right arrow Similar articles in PubMed
Right arrow Alert me to new issues of the journal
Right arrow Download to citation manager
Right arrowReprints and Permissions
Right arrow Copyright Information
Right arrow Books from ASM Press
Right arrow MicrobeWorld
Citing Articles
Right arrow Citing Articles via HighWire
Right arrow Citing Articles via Google Scholar
Google Scholar
Right arrow Articles by Hui, M.
Right arrow Articles by Chan, C. Y.
Right arrow Search for Related Content
PubMed
Right arrow PubMed Citation
Right arrow Articles by Hui, M.
Right arrow Articles by Chan, C. Y.

Copyright © 2009 by the American Society for Microbiology.   For an alternate route to Journals.ASM.org, visit: http://intl-journals.asm.org | More Info»