Antimicrobial activities of six essential oils commonly used as condiments in Brazil against Clostridium perfringens

Abstract Despite recent advances in food production technology, food-borne diseases (FBD) remain a challenging public health concern. In several countries, including Brazil, Clostridium perfringens is among the five main causative agents of food-borne diseases. The present study determines antimicrobial activities of essential oils of six condiments commonly used in Brazil, viz., Ocimum basilicum L. (basil), Rosmarinus officinalis L. (rosemary), Origanum majorana L. (marjoram), Mentha × piperita L. var. Piperita (peppermint), Thymus vulgaris L. (thyme) and Pimpinella anisum L. (anise) against C. perfringens strain A. Chemical compositions of the oils were determined by GC–MS (gas chromatography–mass spectrometry). The identities of the isolated compounds were established from the respective Kováts indices, and a comparison of mass spectral data was made with those reported earlier. The antibacterial activity was assessed from minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) using the microdilution method. Minimum inhibitory concentration values were 1.25 mg mL-1 for thyme, 5.0 mg mL-1 for basil and marjoram, and 10 mg mL-1 for rosemary, peppermint and anise. All oils showed bactericidal activity at their minimum inhibitory concentration, except anise oil, which was only bacteriostatic. The use of essential oils from these common spices might serve as an alternative to the use of chemical preservatives in the control and inactivation of pathogens in commercially produced food systems.

Antimicrobial susceptibility of Clostridium perfringens isolated from piglets with or without diarrhea in Brazil

The minimum inhibitory concentration (MIC) was determined for 13 antibiotics against Clostridium perfringens isolated from Brazilian piglets. The collection of isolates was performed in June to October 2010. All isolates were susceptible to amoxicillin and ceftiofur, whereas most were resistant to tetracycline and lincomycin. Avilamycin and narasin were more effective against isolates from non-diarrheic than from diarrheic piglets. The other antimicrobials were less active in need of high concentrations to inhibit the growth of the C. perfringens type A. These results suggest the need for further studies evaluating molecular factors related to the antimicrobial resistance of C. perfringens.

Efecto de las microondas sobre la sobrevivencia de bacterias esporuladas inoculadas en carne molida / Microwave effect on the survival of sporulated bacteria inoculated in minced meat

Debido a la creciente tendencia de cocinar y recalentar en horno de microondas platillos a base de carne y a la posibilidad de que estos transmitan enfermedades de origen bacteriano, se evaluó la capacidad de sobrevivencia de esporas de bacterias inoculadas en carne molida y tratadas en horno de microonda. Las tortas de carne fueron inoculadas con un número conocido de esporas de Bacillus cereus o Clostridium perfringens y posteriormente cocinadas en horno de microondas Amana de 2450 Hz. Se utilizó la técnica descrita por Vanderzant y Splittstoesser para determinar la tase de sobrevivencia y la actividad de la enxima fosfatasa ácida como parámetro de conocimiento. Las esporas de B. cereus mostraron una tendencia a disminuir en número, conforme aumenta el tiempo de exposición a la radiación, pero si llegar a desaparecer totalmente. Las esporas de C. perfringens disminuyen en número al aumentar el tiempo de exposición, pero presentan un segundo aumento asociado a la germinación de esporas sobrevivientes.

Curvas de crecimiento de clostridium perfringens en caldo tioglicolato y en calcio schedler / Growth curves of clostridium perfringens in tioglicolate broth and Schoedler broth

Con la finalidad de probar el rendimiento de dos caldos de cultivo, usados comunmente para anaerobios, caldo tiaglicolato y caldo schedle. Se evaluaron ambos caldos con una cepa de clostridium perfringens, estableciéndose para dicho fin, curvas de crecimiento a temperaturas óptimas de crecimiento (37ºC y 46ºC) para este microorganismo. En el presente trabajo, no se encontraron diferencias significativas en cuanto al rendimiento de ambos caldos. Por lo que se concluye que, tanto en caldo tiaglicolato, usado para el aislamiento de clostridium perfringens en alimentos, y caldo Schedler, se obtuvieron buenos rendimientos.