Antibiotic resistance in ready to eat foods from hospital and community: what differences?

Background The surveillance data on antimicrobial resistance collected by EARSS previously and currently by EARS-Net (European Antimicrobial Resistance Surveillance Network), illustrate the emergence and spread of microbial resistance to antibiotics in Europe, and help to increase awareness of the problem at the political level, including public health officials, in science and in the general public [1]. Today one of the main routes of transmission of resistant pathogens is represented by ready to eat foods, both animal and vegetable, whose raw materials are sometimes treated with antibiotics in order to preserve their integrity with potential risk of a compromised effectiveness of human treatment of infections [2]. The study was designed to evaluate the prevalence of antibiotic resistance in bacteria belonging to a specific family, the family of Enterobacteriaceae, with the purpose to compare the differences in antibiotic resistance in microorganisms from two different types of craft, community and hospital canteens, and then analyze the possible consequences. Methods All food samples were analyzed according to the ISO 21528-1 method specific for the detection of Enterobacteriaceae in products intended for human consumption The genus, species and the corresponding susceptibility testing were performed using ID32E™ Automated System (bioMérieux) and ATB™ strips read by mini API® updated on the basis of EUCAST breakpoints according to the manufacturer’s recommendations. The descriptive analysis of the data was conducted through the calculation of absolute and relative frequencies while as regards the assessment of the associations between antibiotic resistance and type of table was used the Chi-square test or Fisher's exact test. For the purposes of this analysis the strains with intermediate susceptibility were combined with those resistant. The level of statistical significance was set at 0.05 and the software used was SPSS vs 12. Results We analyzed a total of 325 food samples (238 from community canteens and 87 from hospital canteens), of which 94 (29% of the total) were positive for microorganisms belonging to the family Enterobacteriaceae. The prevalence of positivity in community canteens was 33.2% (N = 79 samples positive for Enterobacteriaceae) while the prevalence of positivity in hospital canteens was 17.2% (N = 15 samples positive for Enterobacteriaceae). The antibiotic that has shown the greatest frequency of resistance was cephalothin in 80.9% of cases followed by ticarcillin in 64.9%, cefotaxime in 56.4% and cefuroxime in 53.2%. With respect to the difference in the prevalence of antibiotic resistant microorganisms between the Community and hospital canteens, the univariate analysis have shown a significant prevalence of strains resistant to piperacillin (p=0.01), ticarcillin (p=0.01), cefotaxime (p=0.03) and cefuroxime (p=0.03) in the samples taken at the community than the hospital canteen. Interestingly, even though the differences were not significant, the prevalence of resistance in sample from community canteen was higher than in those from hospital also for the rest of antibiotics. Conclusions The incidence of findings positive to Enterobacteriaceae in hospital environment (17.2%) is lower than that found in community environment (33.2%) but three of four antibiotics showing the highest rate of resistance are cephalosporins commonly used in hospital because of their broad spectrum of action. Notwithstanding, the significant higher prevalence of strains resistant to piperacillin, ticarcillin, cefotaxime and cefuroxime in the samples taken at the community than the hospital canteen, allow to deduce that the hospital environment is now much safer than that the community from the point of view of the spread of antibiotic resistance. Transmission via foods is quantitatively the most important mode of transmission of antibiotic resistant bacteria and resistance genes from the farm to the consumer, especially if appropriate standards of food hygiene are not consistently applied throughout the food chain Controlling the spread of antibiotic resistance in the environment means protecting those who need antibiotic treatment, in particular hospitalized patients who often contract opportunistic infections against which we have no therapeutic weapon. It may be natural to think that the antibiotic resistance arises and is better distributed in the healthcare setting, where you can think that there is an increased use of antibiotics, but we see a different evidence: the antibiotic resistance develops in the community.