Salmonella enteritidis formadoras de biofilmes são multirresistentes a antimicrobianos

Abstract

Background: The Salmonella Enteritidis is one of the most isolated pathogens in outbreaks of foodborne illness, which can occur due to various factors such as cooking temperature, inadequate storage and cross-contamination. The choice of the appropriate disinfectant in food industries is essential to prevent the spread of contamination and control of biofilms on surfaces. It is also extremely important the concern with resistance to antimicrobials used both as growth promoters and in human and animal treatments, which may generate a selective pressure favoring the emergence of resistant bacteria. Materials, Methods & Results: Twenty samples of Salmonella Enteritidis were tested, 10 from outbreaks of foodborne diseases and 10 of poultry origin, as for the formation of biofilms, antibiotic resistance and sanitizers. The samples were stored frozen in BHI with 20% glycerol. For reactivation were incubated in BHI broth, plated on XLD agar and subsequently performed biochemical tests to check purity. Firstly were evaluated for biofilm formation on polystyrene at temperature of 36 ± 1ºC. We tested the sanitizing resistance to biguanide concentrations 0.6%, 1.0% and 1.5%, peracetic acid at concentrations 0.1%, 0.5% and 1.0%, and quaternary ammonia at concentrations of 0.3%, 1.0% and 2.0%. For tests of antimicrobial resistance the cultures were evaluated front 10 μg ampicillin, 30 μg cephalexin, 30 μg chloramphenicol, 5 μg enrofloxacin, 15 μg erythromycin, 30 μg neomycin, 25 μg sulphazotrim, 300 μg sulfonamides. According to the results, 25% of samples were strongly biofilm formers, 35% moderately formers, 35% weakly formers and 10% not biofilm formers. In sanitizers, quaternary ammonia and peracetic acid were effective at all concentrations and at all times, but tests with biguanide resulted in resistance in the time of 1 min at concentrations 0.6%, 1.0% and 1,5%, at time 5 min at concentrations of 1.0% and 1.5% and at time 10 min at concentrations of 0.6% and 1.0%. As for antimicrobial susceptibility testing, 10 samples of S. Enteritidis presented pattern of multidrug resistance to the antibiotics tested. In relation to the active principles, 25% of S. Enteritidis were resistant to ampicillin, 5% to cephalexin, 55% to enrofloxacin, 90% to erythromycin, 80% to neomycin, 5% to sulphazotrim, 70% to sulfonamides. There was 100% sensitivity to chloramphenicol. Discussion: All S. Enteritidis from outbreaks of foodborne diseases and 80% of S. Enteritidis from poultry products produced biofilm. Regarding S. Enteritidis outbreaks of foodborne illness, 30% were strongly biofilm formers, 50% moderately former and 20% poorly formers. Those isolated from poultry products were 10% strongly formers, 10% moderately formers and 60% poorly formers. Besides the formation of biofilms, 50% of S. Enteritidis were multiresistant to antimicrobials been tested, and of these, 35% corresponded to S. Enteritidis isolates from outbreaks of foodborne illness and only 15% were of poultry origin. Still, 50% of Salmonella Enteritidis were also resistant to biguanide, of which 30% were S. Enteritidis isolates from outbreaks of foodborne illness and 20% isolated from poultry products. These results denotes great relevance due to the possibility of permanence of these microorganisms in food manipulation environments in the form of biofilms and, in the case of transmission to humans, present more difficulty in treatment due to the multidrug resistance.