To determine the prevalence of Methicillin Resistant Staphylococcus aureus (MRSA) isolated in establishments that commercialize raw ground beef and pork chops in Cartagena- Colombia. 160 samples were analyzed through microbiological cultures in Baire Parcker agar, and it was determined the presence of mecA gen that codifies the methicillin resistance and the pvl that codifies the Panton- Valentine leukocidin toxin (PVL) by the multiplex PCR technique. The antibiotic susceptibility profile for MRSA strains was realized by automatized methods and for MSSA strains it was used Kirby Bauver. 66 samples were confirmed as S. aureus by PCR. The prevalence of MRSA was 7.5% and 33.8% of MSSA. The 66% of the strains were isolated from raw ground beef and the 34% of pork chop meat. The isolations presented about 2 – 12% of multi-resistance to the antibiotics used. The MRSA showed resistance to amoxicillin- clavulanate (57%), ampicillin-sulbactam and cefazolin (85%), erythromycin and clindamycin (7%), tetracycline (35%). The 10% of the isolated strains had the gen of PVL toxin and the 71% of those were identified in samples of raw pork meat and the 28% in raw ground beef. This study reports for the first time, how meat raw products commercialized in the city of Cartagena could build a dissemination source of MRSA carrier of PVL toxin that could generate a public health disease.

The study of bacterial communities is highly relevant in relation to the knowledge of global biological biodiversity and the biogeochemical cycles of the planet. Microbiological activity is the basis of ecosystems functioning, among these are the mangroves, which offer a wide variety of goods and services to humanity. Nevertheless, they have been severely impacted by anthropogenic activities such as felling, heavy metal pollution, water enrichment, overexploitation of resources, among others. This research aimed to characterize the culturable bacterial community from the water column and the oyster Crassostrea rhizophorae muscle tissue in a mangrove ecosystem from the Cartagena Bay, Colombian Caribbean as a baseline for future studies on bioremediation treatments. To accomplish this, four samplings were conducted over the course of a year, including contrasting climatic seasons (e.g., windy and rainy), collecting oyster individuals from mangroves and samples from superficial water. The bacterial community comprised 25 species, from which 9 were exclusive for the oyster tissue, 7 for the water column, and 9 generalists isolated from both types of samples. Enterobacter cloacae was the most frequent species during the year, followed by Escherichia coli and Erwinia sp.There were significant differences in the species composition between the sampling months (ANOSIM, R = 0:492; p=D 0:001), because of the presence of a higher number of exclusive species in December than in the other months. Furthermore, the physicochemical variables that presented a major influence on the bacterial community composition were the wind velocity and the dissolved oxygen. The review of this research findings will allow to detect if any of the identified species could be exploited for bioremediation treatments, and it will contribute to the preservation of marine-coastal water bodies biodiversity.

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