| History | | | | Cefepime, Cefotaxime (32 and 256ug/mL), Cefotetan, |
| The principle of the epsilometer test was first | | | | Cefoxotin, Ceftazadime, Ceftizoxime, Ceftriaxone, |
| described in 1988 and was introduced commercially in | | | | Cefuroxime, Cephalothin, Chloramphenicol, |
| 1991 by AB Biodisk. | | | | Ciprofloxacin, Clindamycin, Daptomycin, Doripenem, |
| Principle | | | | Ertapenem, Erythromycin, Fosfomycin, Gatifloxacin, |
| The Etest is basically an agar diffusion method. | | | | Gemifloxacin, Gentamicin (256 and 1024ug/mL), |
| The Etest utilises a rectangular strip that has been | | | | Imipenem, Levofloxacin, Linezolid, Meropenem, |
| impregnated with the drug to be studied. A lawn of | | | | Metronidazole, Minocycline, Moxifloxacin, Ofloxacin, |
| bacteria is inoculated onto the surface an agar plate | | | | Oxacillin, Pip/Tazo, Piperacillin, Quinupri/Dalfopri, |
| and the Etest strip is laid on top; the drug diffuses out | | | | Rifampicin, Ticar/Clav, Tigecycline, Trim/Sulfa, |
| into the agar, producing an exponential gradient of the | | | | Trimethoprim, Vancomycin, |
| drug to be tested. There is an exponential scale printed | | | | Etest for Antifungal Susceptibility Testing |
| on the strip. After 24 hours of incubation, an elliptical | | | | Fluconazole, Itraconazole, Flucytosine, Voriconazole |
| zone of inhibition is produced and the point at which the | | | | Etest for Extended spectrum beta-lactamase |
| ellipse meets the strip gives a reading for the minimum | | | | Detection |
| inhibitory concentration (MIC) of the drug. | | | | Cefotaxime/Clav. acid, Ceftazidime/Clav. acid |
| Validation | | | | References |
| The test has been validated for many organisms | | | | ^ Joyce LF, Downes J, Stockman K, Andrew JH (1 |
| against the broth/agar dilution method and shown to | | | | October 1992). "Comparison of five methods, including |
| have excellent correlation. This is a partial list of | | | | the PDM Epsilometer test (E test), for antimicrobial |
| organisms and antibiotics for which the test has been | | | | susceptibility testing of Pseudomonas aeruginosa". |
| validated. | | | | Journal of Clinical Microbiology 30 (10): 27092713. PMID |
| Pseudomonas aeruginosa: amikacin, ceftazidime, | | | | 1400972. PMC 270503. |
| gentamicin, piperacillin, ticarcillin, tobramycin, | | | | External links |
| The following list (in alphabetical order) reflects Etest | | | | Mendoza MT (1998). "What New in Antimicrobial |
| strips available in the United States for in vitro | | | | Susceptibility Testing?". Phil J Microbiol Infect Dis 27 (3): |
| diagnostic use (as of Jan 2010): Amikacin, Amoxi/clav, | | | | 113115. |
| Amoxicillin, Ampicil/sulb, Ampicillin, Azithromycin, | | | | This microbiology-related article is a stub. You can help |
| Aztreonam, Benzylpenicillin (32 and 256ug/ml), Cefaclor, | | | | Wikipedia by expanding it. |