Evaluation antibacterial and antibiofilm activity of the antimicrobial peptide P34 against Staphylococcus aureus and Enterococcus faecalis

ABSTRACT The adhesion ability of bacteria to abiotic surfaces has important implications in food industries, because these organisms can survive for long periods through the biofilm formation. They can be transferred from one place to another in the industry causing contamination of the food processing environment. In this study, the antibacterial and antibiofilm activities of the antimicrobial peptide P34, characterized as a bacteriocin-like substance (BLS P34) were tested against planktonic and sessile cells of Staphylococcus aureus and Enterococcus faecalis isolated from foods. The BLS P34 showed inhibitory effect against all planktonic cells of E. faecalis. The inhibition of biofilm formation and the eradication of pre-formed biofilm were evaluated with the crystal violet assay and with the reduction of 3-bromide [4,5-dimethylthiazol-2-yl]-2,5-diphenyltetrazolium. The BLS P34 promoted a reduction of percentage of adhered microbial cells on the surface, not being able to perform the complete elimination of biofilm formation. The metabolic activity of S. aureus biofilms decreased considerably between 41-95%. However, E. faecalis cells showed up metabolically stimulated. The BLS P34 has the potential antibiofilm for the species S. aureus. Studies suggest more detailed approaches to a better understanding of the interactions between the antimicrobial and bacterial cells within the biofilm structure.

Virulência e formação de biofilme microbiano por Enterococcus faecalis isolados de swabs cloacais de frangos de corte infectados com Eimeria spp / Virulence and biofilm formation by Enterococcus faecalis isolates from cloacal swabs of broilers infected with Eimeria spp

A dinâmica da microbiota no trato gastrointestinal (TG) de animais pode ser afetada por patógenos, tais como Eimeria spp. Os enterococos são bactérias saprófitas que colonizam o TG de mamíferos e aves. A influência sobre a microbiota intestinal está relacionada com a capacidade de adaptação das bactérias em se aderir às células hospedeiras e de colonizar as células das mucosas. O objetivo deste estudo foi analisar a frequência de genes de virulência ace, agg e operon do bopABCD em Enterococcus faecalis isolados de swabs cloacais de frangos de corte desafiados com Eimeria spp e alimentados com dietas padrões suplementadas ou não com anticoccidiano (monesina) e também avaliar a capacidade dessas cepas em formar biofilmes sob condições in vitro. Um total de 70 E. faecalis foram selecionadas e o gene agg foi mais freqüente em cepas isoladas de frangos de corte alimentados com anticoccidiano (92,3%) quando comparado ao grupo que não recebeu anticoccidiano (70,5%). Por outro lado, os genes ace e do operon bopABCD não demostraram nenhuma diferença significativa entre os dois grupos de frangos (P>0,005). Os E. faecalis isolados de frangos de corte alimentados com anticoccidiano demostraram uma maior frequência de fortes aderentes quando crescendo em meio suplementado com glicose (92,3-88,5%) e urina (77%), quando comparado com enterococos isolados de frangos que não receberam anticoccidiano. Observou-se que E. faecalis isolados de frangos tratados com anticoccidiano mostraram uma maior frequêencia dos genes dos fatores de virulência e de perfil de fortes formadores de biofilme, o que indica uma melhor adaptação dos isolados em ambiente intestinal saudável.

The microbiota dynamics in the gastrointestinal tract (GT) of animals can be disrupted by pathogens, such as Eimeria spp. Enterococci are saprophytic bacteria that colonize the GT of mammals and birds. The influence on the intestinal microbiota is related to the adaptive capacity of bacteria to adhere to host cells and colonize the mucosal cells. The aim of this study was to analyze the frequency of virulence genes ace, agg and bopABCD operon in Enterococcus faecalis isolated from cloacal swabs of broilers challenged with Eimeria spp. and fed with a standard diet supplemented or not with anticoccidial (monensin), and, also to evaluate for the ability of these strains to form biofilms under in vitro conditions. A total of 70 E. faecalis were selected and the agg gene was more frequent in strains isolated from the broilers treated with anticoccidial (92.3%) when compared to the group that not received anticoccidial (70.5%). On the other hand, the ace and bopABCD operon genes showed no significant difference between the two groups of broilers (P>0.005). The E. faecalis isolated from the broilers treated with anticoccidial showed a higher frequency of strong biofilm formation when growing in medium supplemented with glucose (92.3-88.5%) and urine (77%) when compared with enterococci isolated from broilers that not received anticoccidial. It was observed that E. faecalis isolated from broilers treated with anticoccidial showed a higher frequency of virulence factors genes and stronger biofilms formation, indicating better adaptation of the isolates in healthy intestinal environment.