SELECTIVE CULTURE MEDIUM TO ISOLATE CLOSTRIDIUM SPIROFORME FROM RABBIT GUT

Enteritis due to Clostridium spiroforme is an emerging problem of intensive rabbit breading. To control the infection a laboratory support is needed both to diagnose the clostridiosis and to target the therapy. The aetiology can be suspected on the basis of the typical lesions and the bacterioscopical examination of the large intestine content. The isolation of Clostridium spiroforme is necessary to confirm the diagnosis and to evaluate the drug susceptibility. Isolation of Clostridium spiroforme is quite difficult because it requires a rich culture media and needs strictly anaerobic conditions; the microrganism has a low surviving time and produces small colonies not easy to identify. Moreover the isolation can fail because of overgrowing of other anaerobic or facultative anaerobic species (i.e. Proteus spp.). Thus the isolation procedure is too related to the subjective ability of the technician. To avoid the contamination problems a selective culture media (SM) to isolate Clostridium spiroforme was standardized. The commercial PAB medium (Perfringens Agar base,Oxoid) was supplemented with SFP (Shahidi-Ferguson-Perfringens Selective Supplement, Oxoid) and added with a 5% of sheep red blood cells, 500 µg/ml of tylosin (Tylosin tartrate, Sigma) and 12,5 µg/ml of rifampicin (Rifampicin powder, Sigma). The SM was tested with 105 samples of different clinical significance and compared with the control medium. Results evidenced the ability of the SM to isolate Clostridium spiroforme in 79% of samples. Best results were obtained with samples without chemical and physical pre-treatment, so that it was enhanced the sensitivity of the medium while reducing both time and tools consuming. Moreover the capacity of the medium to isolate pure colonies from samples of high clinical relevance (47.5% of isolation against 13.3% of control media) reduces the necessity of specialized personal and makes the procedure easier to standardize.