ABSTRACT
The effect on Salmonella hadar growth was investigated using fresh sterile liquid medium (Pronadisa, Hispanlab) containing aqueous garlic extract (AGE) at different concentration (0, 11, 12, and 13 mg/ml). The garlic extract added at these final concentrations had a bacteriostatic effect on Salmonella hadar. The effect of these bacteriostatic concentration of AGE on the growth of the tested serovar, revealed a pattern of inhibition characterized by: (i) a transitory inhibition phase whose duration was proportional to AGE concentration (ii) a resumed growth phase which showed a lower rate of growth than in uninhibited controls, and (iii) an entry into stationary phase at a lower culture density. The minimal inhibitory concentration and minimum bactericidal concentrations were very close, garlic MIC was 12 mg/ml and the MBC was 14 mg/ml. Among enzymatic activities followed with the API-ZYM system, significant changes during the inhibition phase were detected. These biochemical changes represent an adaptative response towards the garlic stress. Some cellular enzymatic activities disappeared, whereas others were induced or maintained after AGE addition. TEM images of the samples treated with the bacteriostatic concentration of AGE (12 mg/ml) revealed the rupture of cell walls and nonhomogeneous disposition of cytoplasmic materials within treated bacteria.
El efecto sobre el crecimiento de Salmonella hadar fue investigado utilizando un medio líquido estéril fresco (Pronadisa, Hispanlab) conteniendo el extracto acuoso de ajo (EAA) en diferentes concentraciones (0, 11, 12 y 13 mg/ml). El extracto de ajo añadido con estas concentraciones tuvo un efecto bacteriostático sobre Salmonella hadar. La prueba serovar reveló un patrón de inhibición caracterizado por: (i) una fase de inhibición transitoria cuya duración fue proporcional a la concentración de EAA, (ii) una reanudación de la fase de crecimiento, la cual mostró una tasa más baja de crecimiento que controles sin inhibición, y (iii) una ingreso en fase estacionaria con una menor densidad de cultivo. La concentración mínima inhibitoria (CMI) y la concentración mínima bactericida (CMB) fueron muy cercanas, la CMI de ajo fue de 12 mg/ml y la CMB fue de 14 mg/ml. Las actividades enzimáticas seguidas con el sistema API-ZYM, mostraron cambios significativos durante la fase de inhibición. Estos cambios bioquímicos representan una respuesta adaptativa al estrés del ajo. Algunas actividades enzimáticas celulares desaparecieron, mientras que otras fueron inducidas o mantenidas después de la adición de EAA. Las imágenes de MET de las muestras tratadas con la concentración del bacteriostático EAA (12 mg/ml) revelaron la ruptura de las paredes celulares y la disposición no homogénea de materiales citoplasmáticos dentro de las bacterias tratadas.
Subject(s)
Garlic/chemistry , Plant Extracts/pharmacology , Salmonella/growth & development , Salmonella , Salmonella/ultrastructure , Anti-Bacterial Agents/pharmacologyABSTRACT
The gastroenteritis incidence caused by Salmonella Hadar has increased over the last decades worldwide. The uncontrolled use of antimicrobials for treating human patients and veterinary field contributes to increase the multidrug resistance of this serovar. In the present investigation, a total of 179 S. Hadar isolates from different sources of foodchain in Brazil were phage typed and analyzed for their antimicrobial resistance profile. The main S. Hadar phage types isolated were PT 38, PT 39, PT 40, PT 11, PT 34, PT 1 and PT 22. Others phage types as PT 13, PT 19, PT 21, PT 23, PT 31, PT 33 and PT 37 were obtained in low percentages. A total of 35,7 percent S. Hadar strains were resistant to two or more antimicrobials drugs. Furthermore, no resistance to third generation cephalosporin or ciprofloxacin was identified in these strains. Those results appoint to S. Hadar phage types circulating among animals, food and humans, as well as the increasing of multidrug resistance. The surveillance and monitoring of S. Hadar strains based on phage typing and antimicrobial resistance profile are useful for detecting outbreaks, identifying sources of infection and implementing prevention and control measures of salmonellosis.
A incidência de gastrenterite causada por Salmonella Hadar tem aumentado ao longo dos anos em todo o mundo. O uso indiscriminado de antimicrobianos na clínica humana e veterinária tem contribuído para o aumento da multiresistência deste sorovar. No presente estudo, 179 cepas de S. Hadar isoladas de diferentes fontes da cadeia alimentar no Brasil foram fagotipadas e analisadas quanto ao perfil de resistência antimicrobiana. Os principais fagotipos de S. Hadar isolados foram PT 38, PT 39, PT 40, PT 11, PT 34, PT 1 e PT 22. Outros fagotipos como PT 13, PT 19, PT 21, PT 23, PT 31, PT 33 e PT 37 foram obtidos em menores percentagens. Um total de 35,7 por cento das cepas avaliadas foi resistente a dois ou mais antimicrobianos. Por outro lado, não foi observada resistência a cefalosporinas de terceira geração ou ciprofloxacina. Esses resultados apontam para a circulação de fagotipos de S. Hadar entre animais, alimentos e seres humanos, bem como o aumento da multiresistência antimicrobiana. O monitoramento de cepas de S. Hadar baseado na fagotipagem e no padrão de resistência aos antimicrobianos são ferramentas úteis na detecção de surtos, identificação das fontes de infecção, além de auxiliar na implantação de programas de controle e prevenção de salmoneloses.