Poultry Science最新文献

Proteus mirabilis (P. mirabilis) is a Gram-negative, motile opportunistic pathogen with a broad host range. It causes both community- and hospital-acquired infections and is increasingly detected in poultry and food chains, raising food-safety concerns. This study systematically evaluated the prevalence, antimicrobial-susceptibility profiles, and the distribution of resistance genes, virulence-associated genes (VAGs), and metal-tolerance genes in chicken-derived P. mirabilis in Hunan Province. From June 2022 to January 2025, 1,679 chicken cloacal swabs were collected in Hunan; 192 P. mirabilis isolates were recovered (prevalence 11.44%). Antimicrobial-susceptibility testing (AST) was performed on a simple random sample of 118 isolates (118/192, 61.5%) using CLSI-recommended disk diffusion. The results showed that the MDR rate was 72.0% (85/118). Resistance was most frequent to Trimethoprim - Sulfamethoxazole (SXT) (81.4%), Ampicillin (AMP) (79.7%), Ciprofloxacin (CIP) (78.0%), and Gentamicin (GEN) (75.4%), followed by Neomycin (NEO) (63.6%) and Chloramphenicol (CHL) (61.0%). Carbapenem resistance was detected in a subset of isolates, including meropenem (MEM) (6.8%) and imipenem (IPM) (11.0%). Resistance-gene screening identified high prevalence of plasmid-mediated quinolone resistance (PMQR) determinants qnrA 58.9% (113/192) and aac(6')-Ib-cr 59.9% (115/192). The carbapenemase gene blaNDM-1 was detected in 10.4% (20/192) of isolates, and 24.0% (46/192) were positive for vanA. Markers associated with class 1 integrons, including qacEΔ1 and the integrase intI1, were detected in 71.9% and 49.5% of isolates, respectively. Furthermore, copper-tolerance genes copB and pcoA were detected in 49.5% and 10.4% of isolates, respectively. In summary, poultry-derived P. mirabilis in Hunan demonstrated high MDR prevalence and frequent carriage of resistance-, virulence-, and environment-related markers. Our findings enrich the epidemiological data on Proteus mirabilis at the farm level and provide scientific guidance for the prevention and control of this disease.

Salmonella enterica is a major foodborne pathogen associated with poultry, representing a critical challenge for food safety worldwide. Accurate identification of serovar diversity is essential for designing control strategies; however, conventional culture-based methods often underestimate this complexity. In this study, we report the first application of CRISPR-SeroSeq in Ecuador to characterize Salmonella serovar diversity in commercial broilers. A total of 76 flocks (one hose of one farm in different cycles) originated across 19 broiler farms were sampled. All flocks belonged to an integrated poultry company. From all samples, 77.6% tested positive for Salmonella. CRISPR-SeroSeq analysis revealed a clear dominance of serovar Infantis, even within mixed populations. Importantly, serovars of significant public health concern, including Enteritidis and Typhimurium, were detected at low frequencies that would likely be missed by conventional methods. These findings highlight the utility of high-resolution serotyping approaches, providing valuable insights for targeted interventions to improve poultry production biosecurity and food safety.

We examined the antimicrobial resistance of commensal Escherichia coli and occurrence of extended-spectrum beta-lactamase (ESBL)-/AmpC-producing E. coli in organic meat chicken flocks of three different fattening types using a longitudinal study design. Fourteen German small scale meat chicken farms fattening either slow-growing broiler, dual-purpose cockerels or male layer hybrids were sampled between 2023 and 2025. Throughout the fattening period, four consecutive flocks per farm were sampled five times each. Three isolates per sampling time point were picked from MacConkey agar (MCA). Additionally, MCA + 1mg/L cefotaxime (MCA+CTX) was used to selectively screen for ESBL-/AmpC-producing E. coli. In total, 696 commensal E. coli from MCA and 51 ESBL-/AmpC-producing E. coli from MCA+CTX were isolated. Antimicrobial resistance was determined using broth microdilution and minimum inhibitory concentrations were evaluated using epidemiological cut-off values. Throughout the fattening period, most commensal E. coli were susceptible in slow-growing broilers (63.0-80.0%), male layer hybrids (76.9-97.6%) and dual-purpose cockerels (69.0-89.6%). Resistance to ampicillin (11.1%; 77/696), ciprofloxacin (9.9%; 69/696), tetracycline (9.5%; 66/696), and nalidixic acid (8.3%; 58/696) was overall most prevalent in resistant commensal isolates regardless of sampling time point and fattening type. Whole genome sequencing revealed a diverse population among resistant commensal E. coli, with most resistant strains belonging to ST10 or ST155. Clonal dissemination of resistant strains was shown both within flocks or between subsequent flocks of a farm and between different farms. The providing hatchery was shown to have an influence (p < 0.001) on the recovery of resistant isolates. Only 27.5% of all flocks were positive for ESBL-/AmpC-producing E. coli for at least one sampling time point, with none of the flocks being positive throughout the whole fattening period and a high diversity of sequence types. bla_CTX-M-1 (29.2%, 7/24) was the most prevalent ESBL gene identified. This study is the first to describe antimicrobial resistance in different organic meat chicken fattening types in Germany in a longitudinal approach.

Mycoplasma gallisepticum (MG) is a primary avian pathogen that causes chronic respiratory disease, leading to significant economic losses in the poultry industry. This study aimed to investigate the pharmacokinetic/pharmacodynamic (PK/PD) relationship of a novel pleuromutilin derivative, 14-O-[(4-amino-6-hydroxy-pyrimidine-2-yl) thioacetyl] mutilin (APTM), against MG in a chicken infection model to provide a basis for a rational dosage regimen. The in vitro activity of APTM against MG strain S6 was assessed by determining the minimum inhibitory concentration (MIC) and time-kill kinetics. An intratracheal MG infection model was established in chickens. The pharmacokinetic profile was evaluated after single oral administrations of APTM at 5, 15, and 40 mg/kg. The pharmacodynamic efficacy was determined by quantifying the bacterial reduction in the lungs after three consecutive days of oral treatment with doses ranging from 0 to 40 mg/kg. The PK/PD data were integrated and analyzed using an inhibitory sigmoid Emax model. The MIC of APTM against MG S6 was 0.03125 µg/mL, and in vitro time-kill assays demonstrated concentration-dependent bactericidal activity. In chickens, APTM was rapidly absorbed (T_max: 0.25-0.5 h), with both C_max and AUC_0-24h exhibiting excellent dose proportionality (R² > 0.99) over the tested range. In the efficacy study, APTM produced a dose-dependent reduction in lung bacterial load, with a maximum mean reduction of 2.80 log₁₀CFU/mL observed at the 40 mg/kg dose, indicating a bactericidal effect. The PK/PD indices, AUC_0-24h/MIC and C_max/MIC, were both highly correlated with the in vivo antimicrobial effect (R² = 0.9424 and 0.9428, respectively). To achieve a 2-log₁₀CFU/mL reduction in bacterial load, the target AUC_0-24h/MIC value was determined to be 492.75, which corresponds to a calculated daily oral dose of 22 mg/kg. These findings demonstrate the potent efficacy of APTM against MG and provide a quantitative scientific foundation for its therapeutic use in poultry. Specifically, a daily oral dose of 22 mg/kg was identified as the breakpoint for a bactericidal effect (2-log10 reduction), suggesting APTM is a potent candidate for controlling MG infections in poultry.

The prolonged use of antibiotics in poultry production promotes the accumulation and spread of antibiotic resistance genes (ARG), raising concerns for animal health and public safety. Developing effective antibiotic alternatives that support performance while limiting resistance risk is therefore a priority. Using broiler chickens as a model, this study evaluated the effects of Pulsatilla saponins, alone or combined with a compound herbal formulation, on growth performance, immune responses, cecal microbiota, and the intestinal resistome, with an antibiotic-treated group as reference. Growth and immune parameters were integrated with shotgun metagenomic sequencing to characterize microbial and ARG responses to dietary interventions. Compared with antibiotic supplementation, the combination of 0.5% herbal medicine and 0.6% Pulsatilla saponins (ZBZ) combination significantly enhanced immune traits, including spleen index and serum IgA and IgM levels, while increasing cecal microbial diversity and reshaping community composition. Metagenomic analyses showed that antibiotic treatment enriched efflux pump and target modification associated ARG, indicative of a multidrug resistance profile. In contrast, ZBZ markedly reduced the abundance and diversity of multidrug resistance-related ARG. Notably, ZBZ supplementation enriched short-chain fatty acid-producing taxa that were negatively correlated with multiple ARG classes, suggesting that improvements in the intestinal metabolic environment and colonization resistance constrained the expansion of resistant bacteria. Overall, the combined use of Pulsatilla saponins and a compound herbal formulation improved growth and immune performance while reducing intestinal ARG burden through coordinated modulation of the cecal microbiota-resistome axis, providing a sustainable nutritional strategy for antibiotic-reduced poultry production.