Resistance to antibiotics in the normal flora of animals

Abstract

Summary -The normal bacterial flora contains antibiotic resistance genes to various degrees, even in individuals with no history of exposure to commercially prepared antibiotics. Several factors seem to increase the number of antibiotic-resistant bacteria in feces. One important factor is the exposure of the intestinal flora to antibacterial drugs. Antibiotics used as feed additives seem to play an important role in the development of antibiotic resistance in normal flora bacteria. The use of avoparcin as a feed additive has demonstrated that an antibiotic considered "safe" is responsible for increased levels of antibiotic resistance in the normal flora enterococci of animals fed with avoparcin and possibly in humans consuming products from these animals. However, other factors like stress from temperature, crowding, and management also seem to contribute to the occurrence of antibiotic resistance in normal flora bacteria. The normal flora of animals has been studied with respect to the development of antibiotic resistance over four decades, but there are few studies with the intestinal flora as the main focus. The results of earlier studies are valuable when focused against the recent understanding of mobile genetics responsible for bacterial antibiotic resistance. New studies should be undertaken to assess whether the development of antibiotic resistance in the normal flora is directly linked to the dramatic increase in antibiotic resistance of bacterial pathogens. Bacteria of the normal flora, often disregarded scientifically, should be studied with the intention of using them as active protection against infectious diseases and thereby contributing to the overall reduction of use of antibiotics in both animals and humans.normal bacterial flora / antibiotic resistance / feed additives / genetic exchange / preventive management Résumé -Résistance aux antibiotiques dans la flore normale des animaux. La flore bactérienne normale contient des gènes de résistance aux antibiotiques, à des niveaux divers, même chez des individus n'ayant jamais été exposés à des préparations commerciales d'antibiotiques. Plusieurs facteurs semblent augmenter le nombre de bactéries résistantes aux antibiotiques dans les selles. Un facteur important est l'exposition de la flore intestinale aux antibiotiques. Les antibiotiques utilisés comme additif alimentaire semblent avoir un rôle important dans le développement de la résistance aux antibiotiques dans la flore bactérienne normale. L'utilisation de l'avoparcine comme additif alimentaire a montré qu'un antibiotique considéré sans danger est responsable de l'augmentation des taux de résistance aux antibiotiques chez les entérocoques de la flore normale d'animaux ayant reçu de Vet. Res. 32 (2001) 227-241 227

Dietary Fructans and Their Potential Beneficial Influence on Health and Performance Parametrs in Broiler Chickens

“…Among others, antibiotics have commonly been used as growth promoters (AGP) in the intensive animal production for many years. However, the implement the diets with antibiotics resulted in occurrence of antibioticresistant microorganisms (Sørum and Sunde, 2001), also potential pathogens of the genus Streptococcus, Escherichia, Salmonella (Aarestrup et al, 2001;Butaye et al, 2001). Moreover, it can disturb the bacterial ecosystem of the host organism (Andremont, 2000) and may lead to drug residues in products of animal origin (Różańska, 1999).…”

Molecular characterization of vancomycin-resistant enterococci and extended-spectrum β-lactamase-containingEscherichia coliisolates in wild birds from the Azores Archipelago

“…and Escherichia coli are common inhabitants of the gastrointestinal tracts of man and animals (Poeta et al, 2005a;Sorum & Sunde, 2001).…”

Antimicrobial resistance ofEscherichia coliandEnterococcus faecalisin housed laying-hen flocks in Europe

“…In addition, these bacteria acquire antimicrobial resistance faster than other commonly found bacteria [6,8,9]. Commensal Escherichia coli and Enterococcus faecalis are internationally used as respective Gram-negative and Gram-positive indicator bacteria for monitoring antimicrobial resistance because of their common presence in the animal intestinal tract [10][11][12]. Surveillance of antimicrobial resistance is performed in several countries [2], yet these surveillance programmes have generally been focused on cattle, pig and broiler production.…”