Risks Involved in the Use of Enrofloxacin for Salmonella Enteritidis or Salmonella Heidelberg in Commercial Poultry

Advances in enteropathogen control throughout the meat chicken production chain

Enteropathogens, namely Salmonella and Campylobacter, are a concern in global public health and have been attributed in numerous risk assessments to a poultry source. During the last decade, a large body of research addressing this problem has been published. The literature reviewed contains review articles on certain aspects of poultry production chain; however, in the past decade there has not been a review on the entire chain-farm to fork-of poultry production. For this review, a pool of 514 articles were selected for relevance via a systematic screening process (from >7500 original search articles). These studies identified a diversity of management and intervention strategies for the elimination or reduction of enteropathogens in poultry production. Many studies were laboratory or limited field trials with implementation in true commercial operations being problematic. Entities considering using commercial antienteropathogen products and interventions are advised to perform an internal validation and fit-for-purpose trial as Salmonella and Campylobacter serovars and biovars may have regional diversity. Future research should focus on nonchemical application within the processing plant and how a combination of synergisticinterventions through the production chain may contribute to reducing the overall carcass burden of enteropathogens, coupled with increased consumer education on safe handling and cooking of poultry.

Gastrointestinal tract and neuroendocrine system responses of young turkeys to the early administration of antibiotics or feeding a diet containing a coccidiostat

This study investigated the effects of early and short-term administration of an antibiotic or feeding a diet containing a coccidiostat on gastrointestinal function and the blood levels of selected hormones in young turkeys. A total of 1540 Hybrid Converter turkeys were allocated to 4 groups on the day of hatch. Each group consisted of 7 pens with 55 birds per pen. Group ENR was treated with enrofloxacin for the first 5 d of life, group DOX received doxycycline for 5 d and group MON was administered monensin for 84 d. CON birds served as a control group without any antibiotic treatment or MON administration. An analysis of the activity of bacterial enzymes revealed that the cecal microbiota of turkeys were less sensitive to MON than to the other 2 antibiotics. Turkeys subjected to ENR and DOX treatments were characterized by lower (P < 0.05) extracellular activity of cecal bacterial β-glucosidase, compared with groups CON and MON. The extracellular activity of cecal bacterial α-galactosidase and β-galactosidase decreased significantly in response to the experimental treatment with DOX (P < 0.05 vs. CON). Turkeys treated with ENR had higher total activity of bacterial β-galactosidase than those administered DOX or MON. Despite the differences in the enzymatic activity of microbiota, the use of antibiotics did not affect the concentrations of total short-chain fatty acids or ammonia in the cecal digesta of turkeys. A diet containing MON and the early administration of ENR or DOX induced an increase in blood noradrenaline levels (P = 0.004) in 56-day-old turkeys. Early DOX use increased plasma cortisol concentrations (P < 0.001) and decreased plasma serotonin levels (P = 0.006) in 56-day-old turkeys. Over the entire experiment (up to 12 wk of age), the use of MON improved the BW gain of turkeys (P = 0.055) and feed conversion (P = 0.016), compared with the DOX treatment.

Dose-dependent impact of enrofloxacin on broiler chicken gut resistome is mitigated by synbiotic application

Fluoroquinolone agents are considered critical for human medicine by the World Health Organization (WHO). However, they are often used for the treatment of avian colibacillosis in poultry production, creating considerable concern regarding the potential spread of fluoroquinolone resistance genes from commensals to pathogens. Therefore, there is a need to understand the impact of fluoroquinolone application on the reservoir of ARGs in poultry gut and devise means to circumvent potential resistome expansion. Building upon a recent dose optimization effort, we used shotgun metagenomics to investigate the time-course change in the cecal microbiome and resistome of broiler chickens receiving an optimized dosage [12.5 mg/kg body weight (bw)/day], with or without synbiotic supplementation (PoultryStar®, BIOMIN GmbH), and a high dosage of enrofloxacin (50 mg/kg bw/day). Compared to the high dose treatment, the low (optimized) dose of enrofloxacin caused the most significant perturbations in the cecal microbiota and resistome of the broiler chickens, demonstrated by a lower cecal microbiota diversity while substantially increasing the antibiotic resistance genes (ARGs) resistome diversity. Withdrawal of antibiotics resulted in a pronounced reduction in ARG diversity. Chickens receiving the synbiotic treatment had the lowest diversity and number of enriched ARGs, suggesting an alleviating impact on the burden of the gut resistome. Some Proteobacteria were significantly increased in the cecal metagenome of chickens receiving enrofloxacin and showed a positive association with increased ARG burden. Differential abundance (DA) analysis revealed a significant increase in the abundance of ARGs encoding resistance to macrolides-lincosamides-streptogramins (MLS), aminoglycosides, and tetracyclines over the period of enrofloxacin application, with the optimized dosage application resulting in a twofold higher number of affected ARG compared to high dosage application. Our results provide novel insights into the dose-dependent effects of clinically important enrofloxacin application in shaping the broiler gut resistome, which was mitigated by a synbiotic application. The contribution to ameliorating the adverse effects of antimicrobial agents, that is, lowering the spread of antimicrobial resistance genes, on the poultry and potentially other livestock gastrointestinal microbiomes and resistomes merits further study.

Enrofloxacin—The Ruthless Killer of Eukaryotic Cells or the Last Hope in the Fight against Bacterial Infections?

Enrofloxacin is a compound that originates from a group of fluoroquinolones that is widely used in veterinary medicine as an antibacterial agent (this antibiotic is not approved for use as a drug in humans). It reveals strong antibiotic activity against both Gram-positive and Gram-negative bacteria, mainly due to the inhibition of bacterial gyrase and topoisomerase IV enzymatic actions. The high efficacy of this molecule has been demonstrated in the treatment of various animals on farms and other locations. However, the use of enrofloxacin causes severe adverse effects, including skeletal, reproductive, immune, and digestive disorders. In this review article, we present in detail and discuss the advantageous and disadvantageous properties of enrofloxacin, showing the benefits and risks of the use of this compound in veterinary medicine. Animal health and the environmental effects of this stable antibiotic (with half-life as long as 3–9 years in various natural environments) are analyzed, as are the interesting properties of this molecule that are expressed when present in complexes with metals. Recommendations for further research on enrofloxacin are also proposed.

Detection and quantification of multiclass antibiotic residues in poultry products using solid-phase extraction and high-performance liquid chromatography with diode array detection

This article describes the initial study on the simultaneous determination of multiclass antibiotic residues in imported and local frozen poultry specimens, including turkey gizzard and muscle tissues, and chicken muscle tissues, commonly consumed in Ogun State, Nigeria. Minced tissues were treated with phosphate buffer adjusted to pH 7 that was cleaned using C18 SPE-column (Supelclean™) cartridge. For the determination of six antibiotic residues including fluoroquinolones, sulfonamides, and macrolides, a solid-phase extraction method was used, followed by extract analysis using high-performance liquid chromatography-diode array detection (HPLC-DAD). The coefficient of determination (R2) for the external standards for all the analytes ranged between 0.963 and 0.999. The limit of detection (LOD) and quantification (LOQ) ranged between 5.37 - 55.4 μg/kg, and 17.9-185 μg/kg, respectively. Enrofloxacin, sulfadimethoxine, sulfamerazine, and tylosin showed high concentration levels in the frozen poultry beyond acceptable maximum residue limits (MRLs). The six drugs considered in this study were present at higher concentrations in domestic chicken tissues than the permissible level. This suggests that farmers do not observe the cessation period before poultry birds previously treated with antibiotics are sold to consumers thus exposing them to potentially hazardous antibiotic residues.

Co-infection of Salmonella enteritidis with H9N2 avian influenza virus in chickens

Salmonella and avian influenza virus are important pathogens affecting the poultry industry and human health worldwide. In this experimental study, we evaluated the consequences of co-infection of Salmonella enteritidis (SE) with H9N2 avian influenza virus (H9N2-AIV) in chickens. Four groups were included: control group, H9N2-AIV group, H9N2-AIV + SE group, and SE group. Infected chickens were intranasally inoculated with H9N2-AIV at 21 days of age and then orally administered SE on the same day. The birds were monitored for clinical signs, mortality rates, and alterations in body weight. Sera, intestinal fluids, oropharyngeal, and cloacal swabs, and tissue samples were collected at 2, 6, 10, and 14 days post-infection (dpi). Significant increases in clinical signs and mortality rates were observed in the H9N2-AIV + SE group. Moreover, chickens with co-infection showed a significant change in body weight. SE faecal shedding and organ colonization were significantly higher in the H9N2-AIV + SE group than in the SE group. H9N2-AIV infection compromised the systemic and mucosal immunity against SE, as evidenced by a significant decrease in lymphoid organ indices as well as systemic antibody and intestinal immunoglobulin A (IgA) responses to SE and a significant increase in splenic and bursal lesion scores. Moreover, SE infection significantly increased shedding titres and duration of H9N2-AIV. In conclusion, this is the first report of co-infection of SE with H9N2-AIV in chickens, which leads to increased pathogenicity, SE faecal shedding and organ colonization, and H9N2-AIV shedding titre and duration, resulting in substantial economic losses and environmental contamination, ultimately leading to increased zoonoses.

Research Note: Fate and dissemination of Salmonella enterica serovar reading in turkeys at processing using an oral gavage challenge model

This study aimed to evaluate the fate and dissemination of Salmonella Reading (SR) in turkeys using an oral gavage challenge model. One hundred twenty-eight-week-old commercial turkey hens were moved from commercial production to research facilities. Upon arrival, a combination of enrofloxacin, 10 mg/kg, and florfenicol, 20 mg/kg, were orally administered sequentially before comingled placement on fresh pine shavings. Turkeys were challenged with 10⁸ cfu SR by oral gavage on d 4 and 7 postplacement. Subsets were subjected to simulated commercial processing on d 14 (n = 40), 21 (n = 40) and 28 (n = 32) postplacement (corresponding to 10, 11, and 12 wk of age). Stifle joint, skin, trachea, crop, lung, liver + spleen (LS), and ceca were aseptically sampled and cultured for Salmonella recovery and serotyping. SR could not be recovered from stifle joint 14 d post inoculation (PI). However, at 14 d PI, recovery of SR were: Skin 80%; crop 75%; LS 67.5%; lungs 60%; and ceca 57.5%. (P < 0.01). Interestingly, the lowest recovery of SR was observed from trachea (40%). At 21 d PI, the highest rate of positive samples to SR were observed in ceca (87.5%) and crop (67.5%). By 28 d PI, SR was only recovered from ceca (75%); crop (43.8%); lung (34.4%); and LS (21.9%). The results of this study confirms that SR is an emerging problem for the turkey industry and immediate measurements to reduce foodborne pathogens such as Salmonella should target all parts of the supply chain and consumer education about food safety.

Highly clonal relationship among Salmonella Enteritidis isolates in a commercial chicken production chain, Brazil

In this study, we described the comparison among pulsed-field gel electrophoresis (PFGE), random amplified polymorphic DNA (RAPD), ribotyping, and PCR-ribotyping methods for subtyping Salmonella Enteritidis isolated from an industrial chicken production chain. One hundred and eight S. Enteritidis were isolated at all stages of poultry meat processing plant. These isolates were pheno- and genotypically characterized by using antimicrobial susceptibility test, phage typing, RAPD, PFGE, ribotyping, and PCR-ribotyping. The highest antibiotic resistance rates were observed for enrofloxacin (18.5%) followed by furazolidone (15.7%), cefoxitin (1.8%), ciprofloxacin, and ampicillin with 0.9% each one, while seven isolates (6.4%) were pan-susceptible. Most strains belonged to the globally disseminated phage type PT4 (n = 74; 69.2%). Additionally, we identified strains belonging to phage types PT1 (n = 19; 17.8%) and PT7a (n = 14; 13.1%). Moreover, our results showed that these four molecular methods indicate similar results showing high similarity (≥ 90%) among S. Enteritidis strains, suggesting that these isolates appear to be from a common ancestor being spread at all stages of the poultry production chain. In summary, the combined molecular approaches of these methods remain a suitable alternative to efficiently subtyping S. Enteritidis in the absence of high-resolution genotyping methods and these results may serve as a baseline study for development of mitigation strategies.

Mode of Action of Dietary Dexamethasone May Not Be Dependent Upon Microbial Mechanisms in Broilers

Dexamethasone (Dex), a synthetic glucocorticoid (GC), in feed has been shown to increase gut permeability via stress-mediated mechanisms, but the exact mode of action on gut barrier function is not fully understood. Stress has been reported to alter the profile and virulence of intestinal flora predisposing for opportunistic disease. This study aimed to evaluate the relationship between dietary Dex and recoverable intestinal microbial profile in broilers to better understand mode of action and refine future uses of the model. Three experiments were conducted that administered Dex-treated feed for one week in conjunction with the antibiotics BMD (bacitracin methylene disalicylate) or Baytril^® (enrofloxacin) to evaluate if enteric microbial mechanisms were important in Dex-induced permeability. Serum fluorescein isothiocyanate-dextran (FITC-d) and bacterial translocation (BT) have been reported to increase after Dex treatment and were used to assess gut epithelial leakage. Shifts in bacterial profiles were also measured on selective agar. Combining Dex with BMD or Baytril resulted in increased (P < 0.05) serum FITC-d versus Dex-only. Additionally, Baytril did not reduce aerobic BT and bacterial profiles remained similar after Dex. These results suggest a minimal role of intestinal microbes in Dex-induced changes to intestinal barrier function.

Effect of infectious bursal disease (IBD) vaccine on Salmonella Enteritidis infected chickens

BACKGROUND

Chickens infected with both infectious bursal disease virus (IBDV) and Salmonella had higher mortality. In this work, we investigated the effect of IBDV vaccine (modified live-virus bursal disease vaccine, Nobilis strain 228E®) on experimentally infected chickens with Salmonella Enteritidis (SE).

METHODS

Four experimental groups were included in this study, negative control group, 228E®group, 228E®+SE infected group, and SE infected group. Chickens were ocularly administrated 228E® at 12days of age and orally infected with S. Enteritidis at 13days of age. Sera, intestinal fluid, blood, cloacal swabs and tissue samples were collected at 1, 2 and 3weeks post vaccination (PV).

RESULTS

The recorded mortalities were higher in the 228E®+SE infected group, compared to the SE infected group. The anti-S. Enteritidis serum antibody titer and the intestinal mucosal IgA level were higher in the SE infected group at 2 and 3weeks PV, compared to 228E®+SE infected group. S. Enteritidis fecal shedding and organ colonization were significantly higher in the 228E®+SE infected group than the SE infected group at 2 and 3weeks PV. The 228E®+SE group had significantly lower bursa to body weight ratios at 2 and 3weeks PV, as well as had higher bursal lesion scores than the SE infected group. IBDV vaccine depressed the specific-SE systemic and mucosal antibody responses, but did not affect the specific-SE cellular immune responses.

CONCLUSION

Chickens administrated IBDV vaccine, followed by S. Enteritidis infection, could cause a significant effect on the bursa of Fabricius, resulting in failure of systemic and mucosal antibody responses to the S. Enteritidis and reduce the elimination and the clearance of S. Enteritidis.