RESUMO
Dry milk is a particular concern in Mexico, as approximately 150,000 metric tons of dry milk are imported every year at a cost of around $250 million. Dry milk is used to make many products, most of which are dairy products widely distributed among the population covered by welfare programs. The purpose of the study described in this article was to determine the presence of Listeria spp. in imported dry milk samples in Mexico, and to determine the sensitivity of the Listeria monocytogenes isolates to different antimicrobial agents. Listeria isolates (7.8% of 550 bacterial isolates) were identified as L. monocytogenes (53.49%), L. innocua (30.23%), L. seeligeri (13.95%), and L. ivanovii (2.33%). L. monocytogenes strains isolated showed multiresistance to ampicillin, erythromycin, tetracycline, dicloxacillin, and trimethoprim-sulfamethoxazole (9%-14%). The results provide additional evidence of the emergence of multiresistant Listeria strains both in nature and in widely consumed dairy products, representing a potential threat to human health.
Assuntos
Farmacorresistência Bacteriana , Contaminação de Alimentos/análise , Listeria monocytogenes/efeitos dos fármacos , Testes de Sensibilidade Microbiana/métodos , Leite/microbiologia , Animais , Antibacterianos , Humanos , Listeria monocytogenes/isolamento & purificação , MéxicoRESUMO
We analyzed the presence of Listeria spp. in oyster, fish, and seawater samples and tested isolates for antibiotic sensitivity. Listeria monocytogenes was found in 4.5% of fish samples and 8.3% of seawater samples and was not recovered from oysters. Multiresistant environmental strains were found, representing a potential threat to human health.
Assuntos
Antibacterianos/farmacologia , Peixes/microbiologia , Listeria monocytogenes/efeitos dos fármacos , Listeria monocytogenes/isolamento & purificação , Ostreidae/microbiologia , Água do Mar/microbiologia , Animais , Farmacorresistência Bacteriana , México , Testes de Sensibilidade MicrobianaRESUMO
A total of 160 meat product samples were collected from commercial outlets in Mexico City to investigate the presence of different species of Yersinia by the 4 degrees C enrichment method after 1, 3, 5, and 7 days of incubation using alkaline treatment and isolating in cefsulodin-Irgasan-novobiocin and MacConkey agars with Tween 80. Overall, Yersinia spp. were isolated from 27% of the samples analyzed, whereas 40% of the raw and only 13% of the precooked samples were contaminated. Although 2,970 colonies showed Yersinia characteristics, only 706 (24%) actually corresponded to this genus: 49% were Yersinia enterocolitica, 25% Yersinia kristensenii, 15% Yersinia intermedia, 9% Yersinia frederiksenii, and 2% Yersinia aldovae; 10% corresponded to biotype 2, 2% to biotype 3, and 4% to biotype 4. The presence of Yersinia in raw and cooked meat products represents a health risk for consumers in Mexico, where further clinical studies are needed to assess the epidemiological importance of this pathogen.
Assuntos
Microbiologia de Alimentos , Produtos da Carne/microbiologia , Yersinia/isolamento & purificação , Animais , Galinhas , Microbiologia de Alimentos/normas , Produtos da Carne/normas , México , SuínosRESUMO
The presence of Campylobacter spp. was investigated in 100 samples of roasted chicken tacos sold in well-established commercial outlets and semisettled street stands in Mexico City. From 600 colonies displaying Campylobacter morphology only 123 isolates were positive. From these isolates, 51 (41%) were identified as C. jejuni, 23 (19%) as C. coli, and 49 (40%) as other species of this genus. All of the 27 positive samples came from one location where handling practices allowed cross-contamination of the cooked product. The results indicate that these ready-to-consume products are contaminated with these bacteria, representing a potential risk for consumers, especially in establishments lacking adequate sanitary measures to prevent cross-contamination.
Assuntos
Campylobacter coli/isolamento & purificação , Campylobacter jejuni/isolamento & purificação , Microbiologia de Alimentos , Produtos Avícolas/microbiologia , Animais , Galinhas , MéxicoRESUMO
There is poor evidence about the participation of lipoperoxidative processes in liver damage induced by biliary obstruction, thus the aim of this work was to study the role of lipid peroxidation in this model of liver injury. Biliary obstruction was induced in male Wistar rats by ligation of the common bile duct; control animals were sham operated. Rats were sacrificed at different times after surgery. Liver sections were used for glycogen and lipoperoxidation quantification. Markers of liver damage were determined in serum. All serum markers of liver damage increased after 1 day of biliary obstruction. Liver glycogen content decreased 1 day after surgery. On the other hand, lipoperoxidation increased later than markers of liver damage, suggesting that it is a consequence rather than the cause of liver injury. Moreover, administration of colchiceine (a good free-radical scavenger) or vitamin E prevented lipoperoxidation but not liver damage, confirming that lipoperoxidation does not play an important role in liver damage induced by biliary obstruction. This model of liver injury seems to be useful for testing hepatoprotective drugs that do not act as free-radical scavengers.
Assuntos
Colestase/metabolismo , Peroxidação de Lipídeos/fisiologia , Alanina Transaminase/sangue , Fosfatase Alcalina/sangue , Animais , Ductos Biliares/cirurgia , Bilirrubina/sangue , Colestase/patologia , Colchicina/farmacologia , Sequestradores de Radicais Livres/farmacologia , Masculino , Ratos , Ratos Wistar , Vitamina E/farmacologia , gama-Glutamiltransferase/sangueRESUMO
In human and experimental CCl4-liver damage, S-adenosyl-l-methionine-synthetase and/or the intrahepatic content of S-adenosyl-l-methionine, are diminished and in human cirrhosis phospholipid methyltransferase is markedly reduced. Therefore the aim of this study was to investigate the effect of S-adenosyl-l-methionine administration on liver damage induced by 15-day bile duct ligation. Liver damage was analyzed by histological, ultrastructural and biochemical techniques. Biliary obstruction produced an increase in collagen content, dilation of the bile canaliculi and disorganization of mitochondria. These effects were not observed in the bile-duct-ligated group receiving S-adenosyl-l-methionine. Biochemical results showed that bile duct ligation increased serum bilirubins, and alkaline phosphatase and gamma-glutamyl transpeptidase activities. These effects were prevented significantly by S-adenosyl-l-methionine. On the other hand, glycogen content in the liver was depleted while lipid peroxidation was increased by biliary obstruction, S-adenosyl-l-methionine administration prevented these effects. In the bile-duct-ligated group, hepatocyte and erythrocyte plasma membrane Na+/K+ and Ca(2+)-ATPase were lower than in the control group (p < 0.05). Administration of S-adenosyl-l-methionine preserved ATPase activities. The exogenous S-adenosyl-l-methionine supply is probably responsible for restoring transmethylation lost in liver diseases.