Guthrie test

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The Guthrie test (based on Robert Guthrie , 1916–1995) is a bacterial inhibition test and an important part of screening tests in newborns. It was carried out around the 5th day of life for term births, around the 10th day of life for premature births, and is used for the early detection of a certain congenital metabolic disorder, phenylketonuria . Due to sources of error it has meanwhile been replaced by direct determination methods in most hospitals in Germany. It is still in use in the United States, the Netherlands, and Belgium.

history

The test was developed by Robert Guthrie in the early 1960s and first introduced in the United States of America in 1963. In Germany, the test was first introduced in North Rhine-Westphalia in 1966. The first tests were carried out at the hygienic-bacteriological state investigation office in Düsseldorf under the direction of Edip Önöz.

Disambiguation

The Guthrie test is historically the prototype of a screening test in newborns. In common parlance, the term has therefore become a generic term for all screening examinations carried out on newborns . In the real sense, however, it only refers to the investigation described below, developed and introduced by Robert Guthrie.

method

Blood is dripped from the heel of the newborn onto a filter paper card and, after drying, sent to an appropriate laboratory. There, disks of a defined size are punched out and applied to a nutrient medium that has been inoculated with Bacillus subtilis (ATCC 1651). The effect of the inhibitor present in the nutrient medium (2-thienylalanine) is canceled out by the presence of phenylalanine . A growth in the bacterial culture around the blood sample suggests increased phenylalanine levels and the size of the bacterial halo, even the approximate concentration of the amino acid.

Sources of error

Since it was a biological detection method, it is fraught with numerous sources of error. The concentration of phenylalanine depends heavily on the amount of food consumed in the first few days of life. If this was too low, the phenylalanine level in the examined sample can be below the detection limit of the Guthrie test even if the disease is present. In the same way, treatment with an antibiotic can generally inhibit bacterial growth and thus lead to false-negative results in newborns who nevertheless had a phenylalanine metabolism disorder. The Guthrie test is no longer carried out in Germany after much more sensitive direct detection methods for the phenylalanine concentration were developed. In Switzerland, the Guthrie test has been replaced by tandem mass spectrometry (MS / MS) since 2005.

source

  1. ↑ a b Guthrie, R. & Susi, AA (1963): A Simple Method for Detecting Phenylalanine Phenylketonuria in Large Populations of Newborn Infants. In: Pediatrics Vol. 32, pp. 318-343. PMID 14063511

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