Asociación entre resistencia a antibióticos y factores del hospedador y la bacteria en patógenos de transmisión alimentaria
Degree Final Project defended by María Juez García
September 18th, 2019
Salmonellosis is one of the main foodborne zoonosis worldwide and also in the European Union. It is caused by Salmonella enterica subesp. enterica, that can be divided in over 2,500 serotypes. Salmonella is a very ubiquitous bacteria that is also very resistant to a wide range of environmental conditions. Its importance is further complicated by the increasing problem of antimicrobial resistance. Among the large variety of food products associated with its transmission, egg and egg products are among the most frequently reported sources of infection. Salmonellosis mainly leads to gastrointestinal signs, although it is usually self-limiting. However, in severe cases bacteremia may occur, making antibiotic treatment essential. For this reason, increasing levels of resistance to antimicrobials are a significant threat to Public Health.
Here, the level of resistance to nine antimicrobials in a collection of Salmonella isolates recovered from purchased eggs over an 11 year period (2007-2017) in VISAVET Health Surveillance Centre as part of a monitoring program was evaluated.
During this time, isolates belonging to 243 serotypes were recovered, of which Enteritidis, Infantis, Rissen, Anatum and Typhimurium accounted for over 80% of the strain collection. Enteritidis were the most frequent serotype (41%). Overall, the antimicrobial resistance levels were below 10%, except for ciprofloxacin, nalidixic acid, tetracycline and ampicillin. Resistance level varies depending on the serotype, so that Enteritidis and Rissen showed the highest resistance levels, and the lowest were observed in isolates belonging to the serotype Infantis. Overall, 41% of the isolated strains were susceptible to the nine antimicrobials, 27% were resistant to two of them, and none were resistant to more tan six. Almost 8% of the strains were considered multi-resistant.
Although the resistance levels observed in eggs in this study are generally low, results observed for quinolones (35%) along with the high levels of resistance in S. Rissen isolates deserve further consideration. These results, in addition to the changes observed over time in terms of serotypes and resistance observed, highlight the importance of performing this type of surveillance programs
