Stagnitta, P.*; Micalizzi, B.; S. de Guzmán, A.M.
Area de Microbiología, Facultad de Química, Bioquímica y Farmacia, Universidad Nacional de San Luis, San Luis, Argentina.

Clostridium perfringes is a gram positive, spore-forming anaerobic rod. This bacterium can be responsible for food spoilage by the production of an enterotoxin (CPE) which is released from the vegetative cells during sporulation in the intestinal tract. CPE causes food poisoning in humans.
The purpose of this work was to assess the incidence of C. perfringes in meat products consumed in San Luis in relation with sanitation conditions. C. perfringes was enumerated in milk iron medium by the most probable number method (MPN), employing three tubes per dilution to 1/10 in 0.1% peptone water. Simultaneously, countings and isolations were performed on plates in tryptose-sulfite-cycloserin agar medium (TSCA). After subculturing in cooked meat medium, identification was performed by gram coloration and the catalase, gelatin hydrolysis, motility, nitrate reduction, starch hydrolysis, lecithinase, hemolysis, and reverse CAMP factor tests. For the determination of sanitary conditions the following media were used: triptone-glucose agar yeast extract for counting of total aerobes, Mac Conckey and CE broths for total and fecal coliforms, and dichloran-bengal rose-chlortetracyclin agar for fungi and yeast. The following counts were obtained: 10² -10⁶, <10¹-10⁴, and 10³-10⁵, respectively.
From 301 processed samples, 92 (30.56%) were positive for C. perfringes, with counts between 101 and 105 and a correlation between MPN and TSCA of R=0.9999 for counts above 200 bacteria per gram. The correlation between the two count methods used (MPN in milk-iron and TSCA plate) was the following: TSCA=-196.25 + 0.915 x MPN. Only four samples presented MPN above 10⁵/g, the probable infection-causing limit. Colifecals were detected in 115 samples and 54.11% of these also presented C. perfringes. A total of 64.08% of the samples with C. perfringes > 10² concomitantly presented colifecals, which might indicate a link between the presence C. perfringes and the sanitary condition of the samples. 58.26% of the samples with colifecals gave counts above 10², considered as limit by the Argentinian National Food Code. This is an indication of poor sanitation conditions of these products.