[The direct detection of volatile fatty acids by gas chromatography in microbiological diagnosis]

The gas chromatographic analysis of volatile fatty acids (VFA) is of great significance in the diagnosis of anaerobes and anaerobic infections, respectively. The ether extraction commonly used for this purpose is relatively consuming in time and material. In this relation, the presented method of detection of VFA in the aqueous phase directly shows essential simplifications but has a lower sensitivity. Therefore, this method cannot replace the ether extraction to investigate broth cultures of anaerobes for taxonomical purposes. But it enables the determination of VFA with sufficient sensitivity in clinical materials of patients. Herewith, the detection of acetic acid only indicates an infection without anaerobes if the concentration is higher than 20 mg/100 ml. On the contrary, a high correlation exists between the detection of n-butyric acid as well as isovaleric acid and the cultural isolation of anaerobic microorganisms.