RESUMO
The bacteriological analysis and, particularly, the detection of Clostridium botulinum spores from 42 honey samples collected in apiaries of the province of San Luis as well as neighbouring areas of La Pampa, Córdoba and Mendoza, were carried out. Samples were processed by the dilution and centrifugation procedures. For spores detection, culture of the pellets were performed in 2 tubes with cooked meat medium (MCC), one of them warmed up to 80 degrees C for 15 min, and both incubated at 30 degrees C during 7 days. Mice were used to search for toxin in the supernatant. Sediments were also searched for anaerobic bacteria detection in yolk agar plates and in nutritive agar plates for the aerobics. Botulinum toxin type A production was found in one of the MCC cultures. No anaerobic bacteria were isolated. All samples contained Bacillus spp.; 21.4
of the strains, were tentatively classified as B. alvei. A working model for the bacteriological analysis of honey and guides that could be enclosed in publications of official institutions (Figure 1) is proposed.
RESUMO
Recent food listeriosis outbreaks confirm that more faithful isolation and identification methods for Listeria monocytogenes or other potentially pathogen microorganisms are required. Furthermore, the human and animal reservoir role in the ecology of this disease must be established. Listeria spp. in the vizcacha intestinal content was determined by two isolation procedures, starting from 10 g of homogenized samples in 40 ml of PBS. I)0.1 ml was stripped on phenylethanol agar, selective agar for Listeria and acryflavin ceftazidin agar, then incubated at 37 degrees C for 48 h, suspected colonies were identified by preliminary tests (Gram, hemolysis, catalase, esculin hydrolisis and motility at 22 degrees C) and confirmatory tests (indol, methyl red, Voges Proskauer, nitrate and carbohydrate fermentation) (Table 1). Antibiotic susceptibility, protein profile by PAGE and pathogenic power in mice were determined. II) The remaining homogenate was incubated at 4 degrees C in 100 ml of Donnelly and Baigent enrichment broth, weekly or monthly with subcultures until 30 days or 6-8 months, respectively. The subcultures were followed up as in I). A L. seeligeri strain, susceptible to antibiotics suggested for L. monocytogenes and exhibiting resistance to some second and third generation cephalosporins, was isolated (Table 2). The protein profile of both species was coincident, but L. seeligeri was not virulent for mice. The finding of L. seeligeri in an animal (4.0
) used as human feeding source is of interest due to its potential pathogen power.