Caracterización de los principales microorganismos asociados a alimentos de consumo masivo en el Ecuador

Abstract

Foodborne illnesses caused by bacteria and viruses are a major public health problem worldwide, and in Ecuador, there is a lack of information on the microbiological quality of foods. To address this problem, a cross-sectional study was carried out in which samples of popular Ecuadorian foods, such as bolón, encebollado, sauces, ceviche, fruits, fruit juices, fruit salad, ground meat, cheese and raw chicken, were collected in the markets of Quito, Cuenca and Guayaquil. Ten groups of foods commonly consumed in Ecuador were examined and 15 samples for each group were taken from popular markets in three main cities such as Quito, Guayaquil and Cuenca to determine the populations of different microorganisms, including total aerobic mesophilic bacteria, total coliforms, fecal coliforms, Escherichia coli, Salmonella enterica and Listeria monocytogenes, according to local regulations for each type of food. Escherichia coli, although generally a microorganism that lives in a commensalistic symbiotic relationship with its host, encompasses deadly foodborne pathogens such as the enterohemorrhagic serotype and is treated as a potential pathogen in this study. It was highly prevalent in ground beef (40 to 100%) and fresh cheese (60 to 100%) in the three cities, with national averages of 73 and 80%, respectively. It was also often detected among samples of sauces (20 to 40%) and onions (0 to 80%), with national averages of 33 and 40%, respectively. E. coli was not detected in samples of bolón, fruits and fruit juices, but was detected in fruit salads from Guayaquil (80%) and ceviche from Quito (20%). Salmonella enterica was most prevalent in raw chicken samples, ranging between 20 and 60% in the three cities nationwide with an average of 40%. The pathogen was also isolated in sauces (20% prevalence) from Quito and Cuenca, as well as ceviche (20% prevalence) and encebollado from Cuenca (20% prevalence). Listeria monocytogenes was detected in cheese (20 to 40% prevalence) from the three cities, with a national average of 27%, and in bolón (20% prevalence) from Cuenca. The pathogen showed a high prevalence in fruit salads from Guayaquil (80% prevalence) and Cuenca (60% prevalence) but was not detected in fruit salads from Quito. 4 Likewise, studies were carried out to detect the presence of norovirus and hepatitis A in foods. Due to the difficulty of detecting viruses in foods due to the low viral load that usually occur in food matrices, a detection protocol was developed taking as food samples fruits, vegetables (strawberries and spinach respectively) and processed products such as water and sausages since the presence of Norovirus and Hepatitis A are frequent as biological risks in the mentioned foods. Therefore, it was necessary to inhibit certain compounds present in the foods to avoid the degradation of the viral genetic material. The study revealed the presence of norovirus and hepatitis A in food samples, suggesting cross-contamination by food handlers. This work is one of the first studies that characterize the pathogens transmitted by foods of mass consumption in Ecuador.