Longitudinal study on antibiotic susceptibility in commensal E. coli from geese raised in free-range production systems

Comprehensive analysis of biosecurity practices and antimicrobial use in broiler chicken production by integrated operations in Korea

Integrated broiler operations that allow producers to combine various biosecurity and sanitation practices account for approximately 97.6% of chicken meat production in Korea, but it is not well known about the biosecurity level or compliance with regulations for each operation. Therefore, the objective this study was to analyze the current adoption of biosecurity practices and trends in antimicrobial use in 74 farms from 5 major integrated broiler chicken operations (A-E). The highest stock densities of more than 65 birds per 3.3 m2 (0.5 birds/ft2) showed in 66.7 and 33.3% of the farms in operations A and C, respectively. Also, the livability rate of 98% or less was observed in 73.3 and 93.4% of the farms, in operation A and C, respectively, which lower than other operations. Moreover, it was observed that 60.0 and 40.0% of farms in operations B and C reused litter 3 or more times. Among the 74 farms, the most common antimicrobials prescription frequency was 2 times (39.2%), and the prescription to β-lactams antibiotics (45.3%) showed the significantly highest (P < 0.05). The highest administration of antimicrobials was at 15 to 22-days old (42.7%), and most of them were recommended by veterinarian (80.7%). Footbath disinfectant and spraying outside the poultry house were performed in most of the farms (64.9 and 83.8%, respectively), but the use of quicklime (36.5%) and drinking water disinfectant (18.9%) was low in farms. Most of the farms washed vehicles for transportation of poultry (87.8%) and feed (100%) before arriving at the farms, however, 40.5% of the farms used little or no disinfectants when washing the transport vehicles. Moreover, wild birds, and cats and dogs were well controlled on most of the farms (each 94.6%), but only 74.3% of farms offered rodent control programs. Also, only 27.0% of the farms used farm-specific shoes and clothing as well as footbath disinfection for entrance. These findings can be useful in developing policies and guidelines for sustainable and responsible broiler chicken production and reduction of antimicrobial use in Korea.

Goose surfactant protein A inhibits the growth of avian pathogenic Escherichia coli via an aggregation-dependent mechanism that decreases motility and increases membrane permeability

Pulmonary collectins have been reported to bind carbohydrates on pathogens and inhibit infection by agglutination, neutralization, and opsonization. In this study, surfactant protein A (SP-A) was identified from goose lung and characterized at expression- and agglutination-functional levels. The deduced amino acid sequence of goose surfactant protein A (gSP-A) has two characteristic structures: a shorter, collagen-like region and a carbohydrate recognition domain. The latter contains two conserved motifs in its Ca²⁺-binding site: EPN (Glu-Pro-Asn) and WND (Trp-Asn-Asp). Expression analysis using qRT-PCR and fluorescence IHC revealed that gSP-A was highly expressed in the air sac and present in several other tissues, including the lung and trachea. We went on to produce recombinant gSP-A (RgSP-A) using a baculovirus/insect cell system and purified using a Ni²⁺ affinity column. A biological activity assay showed that all bacterial strains tested in this study were aggregated by RgSP-A, but only Escherichia coli AE17 (E. coli AE17, O2) and E. coli AE158 (O78) were susceptible to RgSP-A-mediated growth inhibition at 2-6 h. Moreover, the swarming motility of the two bacterial strains were weakened with increasing RgSP-A concentration, and their membrane permeability was compromised at 3 h, as determined by flow cytometry and laser confocal microscopy. Therefore, RgSP-A is capable of reducing bacterial viability of E. coli O2 and O78 via an aggregation-dependent mechanism which involves decreasing motility and increasing the bacterial membrane permeability. These data will facilitate detailed studies into the role of gSP-A in innate immune defense as well as for development of antibacterial agents.

Escherichia coli Isolated from Organic Laying Hens Reveal a High Level of Antimicrobial Resistance despite No Antimicrobial Treatments

The present study investigated the resistance characteristics of E. coli isolates originating from 18 organic laying hen flocks. E. coli was isolated from different organs at three different time points, resulting in 209 E. coli isolates. The antibiotic susceptibility was determined by applying a microdilution assay. General, a high resistance rate was found. The antibiotic susceptibility was independent from the presence of pathological lesions, the isolation site, or the affiliation to a pathogenic serogroup. The majority of the isolates proved to be multi-drug-resistant (95.70%), of which 36.84% could be categorized as extensively drug-resistant. All isolates were resistant to oxacillin and tylosin. Resistance rates to amoxicillin (67.94%), cefoxitin (55.98%), ceftazidime (82.30%), colistin (73.68%), nalidixic acid (91.87%), streptomycin (42.58%), tetracycline (53.59%), and sulfamethoxazole (95.22%) were high. None of the isolates revealed pan-drug-resistance. A great heterogeneity of resistance profiles was found between isolates within a flock or from different organs of the same bird, even when isolates originated from the same organ. An increase in antimicrobial resistance was found to be correlated with the age of the birds. The fact, that no antibiotic treatment was applied except in two flocks, indicates that resistant bacteria circulating in the environment pose a threat to organic systems.