SENSIBILIDAD in vitro DE Salmonella spp. A DIFERENTES BACTERICIDAS DE USO AGRÍCOLA

Abstract

In vitro SENSITIVITY OF Salmonella spp. TO DIFFERENT AGRICULTURAL BACTERICIDES

In agronomy there are many problems, mainly with pathogenic microorganisms that affect humans directly or indirectly, since they are microscopic organisms that we cannot observe with the naked eye, as is the case of Salmonella spp. This is a fecal bacterium, which means that it is spread through feces, it is Gram-negative, of the family Enterobacteriaceae, and it can be transmitted to foods throughout the chain of production through diverse factors such as incorrect hand washing, use of contaminated water, presence of farm and domestic animals, among others. Fruits and vegetables, as well as animal-based food products such as meat and dairy, have long been recognized as an important part of a healthy diet for humans, but all of these products can contain pathogenic microorganisms that can endanger the health of the consumer. In recent years, there have been reports of increases in the amount of illnesses transmitted by contaminated fruits and vegetables, which have affected both the national and international markets. This is important because exports are one of the main sources of income for producers of food products. As such, it is important to maintain good management in each part of the chain of production, including the field, postharvest, and industry, such as Good Agricultural Practices (GAP), Good Manufacturing Practices (GMP), and Risk Reduction Systems (RRS), which help to ensure food safety. The Mexican market does not implement specific registries of GAP and GMP for food products, but several pathogen control methods that are routinely implemented in the pharmaceutical and medical industries have been utilized in food production. One of the most common methods is the use of antibiotics to eliminate microorganisms that affect human or animal health. However, the effectiveness of the use of antibiotics to prevent bacterial food-borne illness specifically in an agricultural and food-production context remains unclear. For this reason, we evaluated, under in vitro conditions, the effect of the agricultural-use bactericides Kasumin (kasugamycin), Terramicina Agricola 5% (oxytetracycline hydrochloride), Agry-Gent Plus 5000 (gentamicin + oxytetracycline), Hidrobacter (kanamycin sulfate + oxytetracycline hydrochloride), and Comet copper sulfate (copper sulfate pentahydrate) at commercial doses and a negative control (sterile distilled water), on strains of Salmonella 151H, 140028 and Enteritidis. We used the Kirby-Bauer method, which consists of inoculating the aforementioned serotypes onto nutritive agar plates, forming a bacterial lawn, and then placing disks of filter paper previously impregnated with the bactericides for a contact time of 10 minutes. The Petri dishes were incubated at 35°C and we measured the formation of inhibition halos after 24 and 72 hours using a caliper. The results obtained indicated that the strain that showed the largest inhibition halo in the evaluations was Salmonella Enteritidis. Similarly, there was an inhibitory effect of all of the bactericides on all three strains of Salmonella spp. (Enteritidis, Typhi 151H and Typhimorium ATCC140028), which showed a similar effect, with AGRIGENT PLUS 5000 being the agricultural bactericide that showed the highest effectiveness in both evaluations. The bactericides HIDROBACTER and COPPER SULFATE also showed effectiveness, but to a lesser degree (smaller inhibition halos). In contrast, KASUMIN and TERRAMICINA AGRÍCOLA showed no response, similar to the negative control.