Antimicrobial residue detection in chicken yolk samples following administration to egg-producing chickens and effects of residue detection on competitive exclusion culture (PREEMPT) establishment

Antimicrobial Susceptibility of Commensal E. coli Isolated from Wild Birds in Umbria (Central Italy)

The role of wildlife, including birds, in antimicrobial resistance is nowadays a speculative topic for the scientific community as they could be spreaders/sources of antimicrobial resistance genes. In this respect, we aimed to investigate the antimicrobial susceptibility of 100 commensal Escherichia coli strains, isolated from wild birds from an Umbrian rescue centre and admitted to the Veterinary Teaching Hospital of Perugia (Central Italy) mainly for traumatic injuries. The possible presence of Salmonella spp. and ESBL-producing E. coli was also estimated. The highest prevalence of resistance was observed for ampicillin (85%) and amoxicillin/clavulanic acid (47%), probably due to their extensive use in human and veterinary medicine. Seventeen out of the one hundred E. coli isolates (17%) displayed a multidrug-resistance profile, including the beta-lactam category, with the most common resistance patterns to three or four classes of antibiotics. Resistance to ciprofloxacin, cefotaxime and ceftazidime exhibited values of 18%, 17% and 15%, respectively. Eight out of the hundred E. coli isolates (8%) were ESBL and seven showed multidrug resistance profiles. Salmonella spp. was not isolated. Resistance to third-generation cephalosporins, also detected in long-distance migratory birds, suggests the need for monitoring studies to define the role of wild birds in antimicrobial resistance circuits.

Detection of quinolones in commercial eggs obtained from farms in the Espaíllat Province in the Dominican Republic

Previously, we reported the use of quinolones in broiler chickens resulted in residues in retail poultry meat obtained from nine districts in the Santiago Province of the Dominican Republic. Residues in poultry products are a concern due to consumer allergies and the potential to develop antibiotic-resistant bacteria. Given the use of quinolones in poultry production and our previous findings in poultry meat, the objective of this study was to evaluate the presence of quinolone residues in eggs. Samples were collected from 48 different farms located in three of the four municipalities (Moca, Cayetano Germosén, and Jamao) of the Espaíllat Province. Each farm was sampled three times between July and September for a total of 144 samples. Samples were evaluated qualitatively and quantitatively for quinolone residues using the Equinox test. Operation systems (cage or floor), seasonality, and location were considered along with egg-producer sizes that were defined as small scale, <30,000 eggs per day; medium scale, 30,000 to 60,000 eggs per day; or large scale, >60,000 eggs per day. From small-, medium-, and large-scale producers, 69, 50, and 40% of samples were positive for quinolone residues, respectively. A greater number of samples were positive (61%) in floor-laying hen producers compared with those using cages (40%). In the Jamao municipality, 67% of the samples were positive compared with Moca and Cayetano Germosén, where 56 and 25% of samples were positive, respectively. Sampling time had an effect on percent positives: samples collected in July, August, and September were 71, 19, and 63% positive, respectively. Overall, 51% of the samples obtained from eggs produced in the province of Espaíllat were positive for quinolone residues at levels higher than the maximum limits for edible tissue established by the regulatory agencies, including the European Union and U.S. Department of Agriculture. The results obtained from this research confirmed the presence of quinolone residue in eggs, which may present a health risk to some consumers.

Pharmacokinetics of veterinary drugs in laying hens and residues in eggs: a review of the literature

Poultry treated with pharmaceutical products can produce eggs contaminated with drug residues. Such residues could pose a risk to consumer health. The following is a review of the information available in the literature regarding drug pharmacokinetics in laying hens, and the deposition of drugs into eggs of poultry species, primarily chickens. The available data suggest that, when administered to laying hens, a wide variety of drugs leave detectable residues in eggs laid days to weeks after the cessation of treatment.

Probiotic alternatives to reduce gastrointestinal infections: the poultry experience

The intestinal mucosa represents the most active defense barrier against the continuous challenge of food antigens and pathogenic microorganisms present in the intestinal lumen. Protection against harmful agents is conferred by factors such as gastric acid, peristalsis, mucus, intestinal proteolysis, and the intestinal biota. The establishment of beneficial bacterial communities and metabolites from these complex ecosystems has varying consequences for host health. This hypothesis has led to the introduction of novel therapeutic interventions based on the consumption of beneficial bacterial cultures. Mechanisms by which probiotic bacteria affect the microecology of the gastrointestinal tract are not well understood, but at least three mechanisms of action have been proposed: production/presence of antibacterial substances (e.g., bacteriocins or colicins), modulation of immune responses and specific competition for adhesion receptors to intestinal epithelium. The rapid establishment of bacterial communities has been thought to be essential for the prevention of colonization by pathogenic bacteria. Some animal models suggest that the reduction in bacterial translocation in neonatal animals could be associated with an increase in intestinal bacterial communities and bacteriocin-like inhibitory substances produced by these species. This review emphasizes the role of the intestinal microbiota in the reduction of the gastrointestinal infections and draws heavily on studies in poultry.

Efficacy and food safety considerations of poultry competitive exclusion products

Competitive exclusion (CE) products are anaerobic cultures of bacteria that are applied to poultry hatchlings to establish a protective enteric microbiota that excludes intestinal colonization by human food-borne pathogens. For safety of the poultry flock and human consumers, the identities of bacteria in CE products need to be known. A CE product is a culture of intestinal contents from adult chickens. It may be microbiologically defined by analysis of bacteria isolated from the culture, but many bacteria are hard to reliably isolate, identify, and characterize with conventional techniques. Sequence analysis of 16S ribosomal RNA (rRNA) genes may be more reliable than conventional techniques to identify CE bacteria. Bacteria in CE products may contain antimicrobial drug resistance and virulence mechanisms that could be transferred to the enteric bacteria of the food animal and to the human consumer. Detection methods for specific antimicrobial drug resistance and virulence genes and the integrase genes of conjugative transposons, mostly utilizing PCR technology, are being developed that can be applied to assess these risks in CE bacteria. With improvements in efficacy, bacterial identification, and detection and control of the possible risks of gene transfer, CE product technology can be made a more effective food safety tool.

Determination of the fluoroquinolone enrofloxacin in edible chicken muscle by supercritical fluid extraction and liquid chromatography with fluorescence detection

A supercritical fluid extraction (SFE) method for the extraction of enrofloxacin from a chicken breast muscle was examined. A liquid chromatograph, equipped with a fluorescence detector, was used for the detection of enrofloxacin. Optimal extraction parameters, such as extraction time, supercritical fluid volume, modifier concentration, pressure, and temperature, were determined by examining SFE recoveries from control muscle samples spiked with enrofloxacin at different levels. In all of the experiments, high recovery values were observed, ranging from 101 to 104%. The extraction of enrofloxacin from real muscle samples was examined in chickens that were treated orally with enrofloxacin. Extraction was carried out by the SFE method after each oral treatment and under optimal extraction conditions at set intervals over time. The SFE, combined with liquid chromatographic analysis, showed that the concentration of enrofloxacin in the chicken muscles decreased continuously with time, giving a negligible concentration 72 h after the treatment. These results suggest that SFE is a useful approach for the extraction of enrofloxacin from chicken breast muscles.

Evaluation of aviguard, a commercial competitive exclusion product for efficacy and after-effect on the antibody response of chicks to Salmonella

The competitive exclusion (CE) action of Aviguard (AG) and its effects on the antibody response of chicks were evaluated in this study. We observed that AG protected the chicks from overwhelming colonization. Fourteen days after infection, fewer AG-pretreated than nonpretreated chicks shed salmonellae from their coloaca in both infected groups, although much less from SE-infected chicks. Antibody titers of sera produced to Salmonella typhimurium (ST) and SE in pretreated and non-pretreated chicks were not significantly different. Immunoblotting showed that these antibodies reacted with SDS-PAGE-separated 71.4, 67.7, 44.0, and 30.3 kDa proteins detectable in the test strains. Few weak bands of doubtful significance were observed in the cross-reaction between the sera of ST- and SE-infected chicks with ST and SE antigens, respectively. Our study showed that AG protected chicks from overwhelming colonization by salmonellae, and neither altered the antigenic proteins of infecting salmonellae nor their recognition by specific antibodies produced in response to the infection.