Development of colorimetric microtiter plate assay for assessment of antimicrobials against Acanthamoeba

James McBride, Paul R. Ingram, Fiona L. Henriquez, Craig W. Roberts

Research output: Contribution to journalArticle

Abstract

We have developed and optimized a 96-well microtiter plate assay, based on the reduction of alamarBlue, to assess the efficacies of much needed new antimicrobials against Acanthamoeba species. This assay has been optimized for determination of drug efficacy against two potentially pathogenic species, Acanthamoeba castellanii and Acanthamoeba polyphaga, and has been validated by comparison of their relative susceptibilities to chlorhexidine, a drug widely used to treat Acanthamoeba keratitis. The results demonstrate that the assay is comparable to a manual counting assay and that A. polyphaga is more resistant to chlorhexidine than A. castellanii. Thus, by use of the manual counting assay, 3.125 microM chlorohexidine was almost completely effective against A. castellanii, whereas this concentration was less than 20% effective against A. polyphaga. Similar results were obtained by the alamarBlue assay. The new assay was used to determine the relative susceptibilities of A. castellanii and A. polyphaga to the alkylphosphocholines (APCs) hexadecylphosphocholine (hexadecyl-PC; miltefosine) and octadecylphosphocholine (octadecyl-PC) as well as an alkylgycerolphosphocholine, edelfosine. Both APCs studied were equally effective against A. castellanii, but octadecyl-PC was less effective than hexadecyl-PC against A. polyphaga. Both APCs were more effective than edelfosine against both Acanthamoeba species. A. polyphaga was found to be significantly less susceptible to each of the phosphocholine analogues. The newly described assay offers a number of advantages over those described previously. It is less labor-intensive than previously described assays and is sensitive and rapid, and the results can be read in a nonsubjective manner. As it is based on a standard 96-well, microtiter plate, it is amenable to automation and high throughput.

Original languageEnglish
Pages (from-to)629-634
Number of pages6
JournalJournal of Clinical Microbiology
Volume43
Issue number2
DOIs
Publication statusPublished - Feb 2005
Externally publishedYes

Fingerprint

Acanthamoeba castellanii
Acanthamoeba
miltefosine
Chlorhexidine
Acanthamoeba Keratitis
Phosphorylcholine
Automation
Pharmaceutical Preparations

Keywords

  • Acanthamoeba
  • Acanthamoeba castellanii
  • Amebicides
  • Animals
  • Chlorhexidine
  • Colony Count, Microbial
  • Colorimetry
  • Culture Media
  • Indicators and Reagents
  • Oxazines
  • Parasitic Sensitivity Tests
  • Phospholipid Ethers
  • Phosphorylcholine
  • Xanthenes

Cite this

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title = "Development of colorimetric microtiter plate assay for assessment of antimicrobials against Acanthamoeba",
abstract = "We have developed and optimized a 96-well microtiter plate assay, based on the reduction of alamarBlue, to assess the efficacies of much needed new antimicrobials against Acanthamoeba species. This assay has been optimized for determination of drug efficacy against two potentially pathogenic species, Acanthamoeba castellanii and Acanthamoeba polyphaga, and has been validated by comparison of their relative susceptibilities to chlorhexidine, a drug widely used to treat Acanthamoeba keratitis. The results demonstrate that the assay is comparable to a manual counting assay and that A. polyphaga is more resistant to chlorhexidine than A. castellanii. Thus, by use of the manual counting assay, 3.125 microM chlorohexidine was almost completely effective against A. castellanii, whereas this concentration was less than 20{\%} effective against A. polyphaga. Similar results were obtained by the alamarBlue assay. The new assay was used to determine the relative susceptibilities of A. castellanii and A. polyphaga to the alkylphosphocholines (APCs) hexadecylphosphocholine (hexadecyl-PC; miltefosine) and octadecylphosphocholine (octadecyl-PC) as well as an alkylgycerolphosphocholine, edelfosine. Both APCs studied were equally effective against A. castellanii, but octadecyl-PC was less effective than hexadecyl-PC against A. polyphaga. Both APCs were more effective than edelfosine against both Acanthamoeba species. A. polyphaga was found to be significantly less susceptible to each of the phosphocholine analogues. The newly described assay offers a number of advantages over those described previously. It is less labor-intensive than previously described assays and is sensitive and rapid, and the results can be read in a nonsubjective manner. As it is based on a standard 96-well, microtiter plate, it is amenable to automation and high throughput.",
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Development of colorimetric microtiter plate assay for assessment of antimicrobials against Acanthamoeba. / McBride, James; Ingram, Paul R.; Henriquez, Fiona L.; Roberts, Craig W.

In: Journal of Clinical Microbiology, Vol. 43, No. 2, 02.2005, p. 629-634.

Research output: Contribution to journalArticle

TY - JOUR

T1 - Development of colorimetric microtiter plate assay for assessment of antimicrobials against Acanthamoeba

AU - McBride, James

AU - Ingram, Paul R.

AU - Henriquez, Fiona L.

AU - Roberts, Craig W.

PY - 2005/2

Y1 - 2005/2

N2 - We have developed and optimized a 96-well microtiter plate assay, based on the reduction of alamarBlue, to assess the efficacies of much needed new antimicrobials against Acanthamoeba species. This assay has been optimized for determination of drug efficacy against two potentially pathogenic species, Acanthamoeba castellanii and Acanthamoeba polyphaga, and has been validated by comparison of their relative susceptibilities to chlorhexidine, a drug widely used to treat Acanthamoeba keratitis. The results demonstrate that the assay is comparable to a manual counting assay and that A. polyphaga is more resistant to chlorhexidine than A. castellanii. Thus, by use of the manual counting assay, 3.125 microM chlorohexidine was almost completely effective against A. castellanii, whereas this concentration was less than 20% effective against A. polyphaga. Similar results were obtained by the alamarBlue assay. The new assay was used to determine the relative susceptibilities of A. castellanii and A. polyphaga to the alkylphosphocholines (APCs) hexadecylphosphocholine (hexadecyl-PC; miltefosine) and octadecylphosphocholine (octadecyl-PC) as well as an alkylgycerolphosphocholine, edelfosine. Both APCs studied were equally effective against A. castellanii, but octadecyl-PC was less effective than hexadecyl-PC against A. polyphaga. Both APCs were more effective than edelfosine against both Acanthamoeba species. A. polyphaga was found to be significantly less susceptible to each of the phosphocholine analogues. The newly described assay offers a number of advantages over those described previously. It is less labor-intensive than previously described assays and is sensitive and rapid, and the results can be read in a nonsubjective manner. As it is based on a standard 96-well, microtiter plate, it is amenable to automation and high throughput.

AB - We have developed and optimized a 96-well microtiter plate assay, based on the reduction of alamarBlue, to assess the efficacies of much needed new antimicrobials against Acanthamoeba species. This assay has been optimized for determination of drug efficacy against two potentially pathogenic species, Acanthamoeba castellanii and Acanthamoeba polyphaga, and has been validated by comparison of their relative susceptibilities to chlorhexidine, a drug widely used to treat Acanthamoeba keratitis. The results demonstrate that the assay is comparable to a manual counting assay and that A. polyphaga is more resistant to chlorhexidine than A. castellanii. Thus, by use of the manual counting assay, 3.125 microM chlorohexidine was almost completely effective against A. castellanii, whereas this concentration was less than 20% effective against A. polyphaga. Similar results were obtained by the alamarBlue assay. The new assay was used to determine the relative susceptibilities of A. castellanii and A. polyphaga to the alkylphosphocholines (APCs) hexadecylphosphocholine (hexadecyl-PC; miltefosine) and octadecylphosphocholine (octadecyl-PC) as well as an alkylgycerolphosphocholine, edelfosine. Both APCs studied were equally effective against A. castellanii, but octadecyl-PC was less effective than hexadecyl-PC against A. polyphaga. Both APCs were more effective than edelfosine against both Acanthamoeba species. A. polyphaga was found to be significantly less susceptible to each of the phosphocholine analogues. The newly described assay offers a number of advantages over those described previously. It is less labor-intensive than previously described assays and is sensitive and rapid, and the results can be read in a nonsubjective manner. As it is based on a standard 96-well, microtiter plate, it is amenable to automation and high throughput.

KW - Acanthamoeba

KW - Acanthamoeba castellanii

KW - Amebicides

KW - Animals

KW - Chlorhexidine

KW - Colony Count, Microbial

KW - Colorimetry

KW - Culture Media

KW - Indicators and Reagents

KW - Oxazines

KW - Parasitic Sensitivity Tests

KW - Phospholipid Ethers

KW - Phosphorylcholine

KW - Xanthenes

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DO - 10.1128/JCM.43.2.629-634.2005

M3 - Article

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EP - 634

JO - Journal of Clinical Microbiology

JF - Journal of Clinical Microbiology

SN - 0095-1137

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