CELLULAR FATTY-ACID ANALYSIS IN THE DIFFERENTIATION OF CLOSTRIDIUM SPECIES IN THE CLINICAL MICROBIOLOGY LABORATORY

The identification of Clostridium species can be problematic for the d iagnostic microbiology laboratory. The introduction of the MIDI Microb ial Identification System (MIS) has enabled personnel in diagnostic la boratories to perform cellular fatty acid analyses on a variety of mic roorganisms. We used the Virginia Polytechnic Institute (Blacksburg, V A) Anaerobe Library (Moore Version 3.8) to perform analyses on 216 str ains representing 18 species of Clostridium. The organisms were charac terized with use of traditional biochemical methods that employ prered uced anaerobically sterilized media and other reference diagnostic met hods. The MIS identified 86% of the strains correctly to the species l evel without the need for supplemental tests, and identified an additi onal 6% of the strains to species levels with the aid of a few supplem ental tests. Only 3% of strains were identified by genus incorrectly. The cellular fatty acid patterns of selected, medically important clos tridia were so distinctive that 100% of these species were identified correctly. The MIS has many practical benefits, including speed of ide ntification, and few disadvantages (such as equipment cost) for the cl inical microbiology laboratory.