Staphylococcus aureus in Some Brazilian Dairy Industries: Changes of Contamination and Diversity.

Staphylococcus aureus, a major food-poisoning pathogen, is a common contaminant in dairy industries worldwide, including in Brazil. We determined the occurrence of S. aureus in five dairies in Brazil over 8 months. Of 421 samples, 31 (7.4%) were positive for S. aureus and prevalence varied from 0 to 63.3% between dairies. Sixty-six isolates from the 31 samples were typed by Multi-Locus Sequence Typing to determine if these isolates were persistent or continuously reintroduced. Seven known sequence types (STs), ST1, ST5, ST30, ST97, ST126, ST188 and ST398, and four new ST were identified, ST3531, ST3540, ST3562 and ST3534. Clonal complex (CC) 1 (including the four new ST), known as an epidemic clone, was the dominant CC. However, there were no indications of persistence of particular ST. The resistance toward 11 antibiotic compounds was assessed. Twelve profiles were generated with 75.8% of strains being sensitive to all antibiotic classes and no Methicillin-resistant S. aureus (MRSA) strains were found. The enterotoxin-encoding genes involved in food-poisoning, e.g., sea, sed, see, and seg were targeted by PCR. The two toxin-encoding genes, sed and see, were not detected. Only three strains (4.5%) harbored seg and two of these also harbored sea. Despite the isolates being Methicillin-sensitive S. aureus (MSSA), the presence of CC1 clones in the processing environment, including some harboring enterotoxin encoding genes, is of concern and hygiene must have high priority to reduce contamination.

Listeria monocytogenes incidence changes and diversity in some Brazilian dairy industries and retail products.

Listeria monocytogenes can cause listeriosis, a severe foodborne disease. In Brazil, despite very few reported cases of listeriosis, the pathogen has been repeatedly isolated from dairies. This has led the government to implement specific legislation to reduce the hazard. Here, we determined the incidence of L. monocytogenes in five dairies and retail products in the Southeast and Midwest regions of Brazil over eight months. Of 437 samples, three samples (0.7%) from retail and only one sample (0.2%) from the dairies were positive for L. monocytogenes. Thus, the contamination rate was significantly reduced as compared to previous studies. MultiLocus Sequence Typing (MLST) was used to determine if contamination was caused by new or persistent clones leading to the first MLST profile of L. monocytogenes from the Brazilian dairy industry. The processing environment isolate is of concern being a sequence-type (ST) 2, belonging to the lineage I responsible for the majority of listeriosis outbreaks. Also, ST3 and ST8 found in commercialized cheese have previously been reported in outbreaks. Despite the lower incidence, dairy products still pose a potential health risk and the occurrence of L. monocytogenes in dairies and retail products emphasize the need for continuous surveillance of this pathogen in the Brazilian dairy industry.

Reclassification of Alteromonas fuliginea (Romanenko et al. 1995) as Pseudoalteromonas fuliginea comb. nov. and an emended description.

A new aerobic marine bacterium, strain S3431, was isolated from swab samples of an unidentified polychaete near Canal Concepción, Chile. This strain was thought to represent a new taxon within the genus Pseudoalteromonas. Although DNA-DNA reassociation values showed less than 70 % genomic DNA relatedness to established Pseudoalteromonas type strains, it shared 78 % DNA-DNA relatedness with Alteromonas fuliginea DSM 15748 (=KMM 216) (Romanenko et al., 1994). A. fuliginea has later been considered a heterotypic synonym of Pseudoalteromonas citrea(Ivanova et al., 1998). Relatedness between strains S3431, A. fuliginea DSM 15748 and the type strain P. citrea LMG 12323T was therefore studied. Physiological traits and genomic information were shared at a high level by strains S3431 and DSM 15748, but not between these and P. citrea LMG 12323T. There was only approximately 20 % DNA-DNA relatedness between P. citrea LMG 12323T and strains S3431 and DSM 15748. Based on the available phylogenetic and phenotypic data, the reclassification of A. fuliginea DSM 15748 (Romanenko et al., 1995) → Pseudoalteromonas citrea(Ivanova et al., 1998) as Pseudoalteromonas fuligineacomb. nov. is proposed, and strain S3431 should be assigned to this new species. The name Pseudoalteromonas fuliginea is proposed with KMM 216T (=DSM 15748T=CIP 105339T) as the type strain.

Antilisterial activity of a Carnobacterium piscicola isolated from Brazilian smoked fish (surubim [Pseudoplatystoma sp.]) and its activity against a persistent strain of Listeria monocytogenes isolated from surubim.

Data on the prevalence and growth of Listeria monocytogenes in lightly preserved fish products from subtropical and tropical regions are very scarce. Our research describes L. monocytogenes that was detected in 5% of the packages of cold-smoked surubim, a native Brazilian freshwater fish that we analyzed, and shows that the strains isolated were of the same random amplified polymorphic DNA subtype as the strains that were isolated from the same factory 4 years earlier. A bacteriocinogenic strain of Carnobacterium piscicola (strain C2), isolated from vacuum-packed cold-smoked surubim, and two C. piscicola strains, isolated from vacuum-packed, cold-smoked salmon, were capable of limiting or completely inhibiting the growth of an L. monocytogenes (strain V2) isolated from surubim in fish peptone model systems incubated at 10 degrees C. Monocultures of L. monocytogenes reached 108 CFU/ml (g), whereas the growth of L. monocytogenes was completely inhibited by C. piscicola C2. The bacteriocinogenic C. piscicola A9b+ and its nonbacteriocinogenic mutant A9b- reduced maximum Listeria levels by 2 to 3 log units. Both bacteriocinogenic C. piscicola strains prevented listerial growth in cold-smoked fish juices (surubim and salmon). Although the carnobacteria grew poorly on cold-smoked surubim at 10 degrees C, the strains were able to reduce maximum Listeria counts by 1 to 3 log units in an artificially inoculated product (surubim). We conclude that Brazilian smoked fish products harbor L. monocytogenes and should be stabilized against the growth of the organism. C. piscicola C2 has the potential for use as a bioprotective culture in surubim and other lightly preserved fish, but further studies are required to optimize its effect.