RESUMEN
OBJECTIVE: To determine antimicrobial effects of caprylic acid and its derivatives, monocaprylin and sodium caprylate, on Dermatophilus congolensis and to determine effects of caprylic acid on the ultrastructure of D congolensis by use of transmission electron microscopy (TEM). SAMPLE: 3 strains of D congolensis (33411, 33413, and 14639). PROCEDURES: Strains of D congolensis were incubated separately under anaerobic conditions at 37°C for up to 48 hours in brain heart infusion (BHI) broth that was supplemented with various concentrations of caprylic acid (7.5, 12.5, 15, 17.5, or 20mM), monocaprylin (2.5, 5, 7.5, or 10mM), or sodium caprylate (15, 50, 60, 70, 100, or 120mM) or contained no antimicrobial treatment. After incubation, bacterial counts were determined by means of plating in triplicate on BHI-agar plates. Caprylic acid-treated or untreated D congolensis samples were embedded in epoxide resin for TEM; cross sections were examined for structural damage. RESULTS: Minimum inhibitory concentrations of caprylic acid, monocaprylin, and sodium caprylate against D congolensis were 7.5, 2.5, and 15 mM, respectively. Minimum bactericidal concentrations of caprylic acid, monocaprylin, and sodium caprylate against D congolensis were 15, 5, and 70 mM, respectively. Examination via TEM revealed that a 15-mM concentration of caprylic acid disintegrated the plasma membrane of D congolensis. CONCLUSIONS AND CLINICAL RELEVANCE: Results indicated that caprylic acid, monocaprylin, and sodium caprylate could potentially be used to treat D congolensis infections. However, in vivo studies should be undertaken to determine whether these compounds can be considered as treatment options.
Asunto(s)
Infecciones por Actinomycetales/veterinaria , Actinomycetales/efectos de los fármacos , Antibacterianos/farmacología , Caprilatos/farmacología , Enfermedades de los Caballos/microbiología , Enfermedades Cutáneas Bacterianas/veterinaria , Actinomycetales/ultraestructura , Infecciones por Actinomycetales/tratamiento farmacológico , Animales , Glicéridos/farmacología , Enfermedades de los Caballos/tratamiento farmacológico , Caballos , Enfermedades Cutáneas Bacterianas/tratamiento farmacológico , Enfermedades Cutáneas Bacterianas/microbiologíaRESUMEN
The effect of trans-cinnamaldehyde (TC) on the inactivation of Escherichia coli O157:H7 in undercooked ground beef patties was investigated. A five-strain mixture of E. coli O157:H7 was inoculated into ground beef (7.0log CFU/g), followed by addition of TC (0, 0.15, and 0.3%). The meat was formed into patties and stored at 4 degrees C for 5 days or at -18 degrees C for 7 days. The patties were cooked to an internal temperature of 60 or 65 degrees C, and E. coli O157:H7 was enumerated. The numbers of E. coli O157:H7 did not decline during storage of patties. However, cooking of patties containing TC significantly reduced (P<0.05) E. coli O157:H7 counts, by >5.0log CFU/g, relative to the reduction in controls cooked to the same temperatures. The D-values at 60 and 65 degrees C of E. coli O157:H7 in TC-treated patties (1.85 and 0.08min, respectively) were significantly lower (P<0.05) than the corresponding D-values for the organism in control patties (2.70 and 0.29min, respectively). TC-treated patties were more color stable and showed significantly lower lipid oxidation (P<0.05) than control samples. TC enhanced the heat sensitivity of E. coli O157:H7 and could potentially be used as an antimicrobial for ensuring pathogen inactivation in undercooked patties. However detailed sensory studies will be necessary to determine the acceptability to consumers of TC in ground beef patties.