Antibiotic Application and Resistance in Swine Production in China: Current Situation and Future Perspectives

Antimicrobial resistance and phylogenetic relatedness of extended-spectrum ß-lactamase (ESBL)-producing Escherichia coli in peridomestic rats (Rattus norvegicus and Rattus tanezumi) linked to city areas and animal farms in Hong Kong

Extended-spectrum β-lactamase-producing Escherichia (E.) coli (ESBL-EC) in the clinical setting have emerged as a major threat to public and animal health. Wildlife, including Rattus spp. may serve as reservoirs and spreaders of ESBL-EC in the environment. Peridomestic rats are well adapted to living in proximity to humans and animals in a variety of urban and agricultural environments and may serve as sentinels to identify variations of ESBL-EC within their different habitats. In this study, a set of 221 rats (Rattus norvegicus, R. tanezumi, R. andamanensis, and Niviventer huang) consisting of 104 rats from city areas, 44 from chicken farms, 52 from pig farms, and 21 from stables of horse-riding schools were screened for ESBL-EC. Overall, a total of 134 ESBL-EC were isolated from the caecal samples of 130 (59%) rats. The predominant blaESBL genes were blaCTX-M-14, blaCTX-M-15, blaCTX-M-55, and blaCTX-M-65. Phylogenetic analysis revealed a total of 62 sequence types (STs) and 17 SNP clusters. E. coli ST10 and ST155 were common to ESBL-EC from city areas and chicken farms, and ST44 were found among ESBL-EC from city areas and pig farms. Extra-intestinal pathogenic E. coli (ExPEC) ST69, ST131 and ST1193 were found exclusively among rats from city areas, and avian pathogenic E. coli (APEC) ST177 was restricted to ESBL-EC originating from chicken farms. Phylogenetic analysis showed that the populations of rodent ESBL-EC from city areas, chicken farms and pig farms were genetically different, suggesting a certain degree of partitioning between the human and animal locations. This study contributes to current understanding of ESBL-EC occurring in rats in ecologically diverse locations.

Whole genome sequencing analysis on antibiotic-resistant Escherichia coli isolated from pig farms in Banten Province, Indonesia

IMPORTANCE

The emergence and rapid increase in the incidence of multidrug-resistant (MDR) bacteria in pig farms has become a serious concern and reduced the choice of effective antibiotics.

OBJECTIVE

This study analyzed the phylogenetics and diversity of antibiotic resistance genes (ARGs) and molecularly identified the source of ARGs in antibiotic-resistant Escherichia coli isolated from pig farms in Banten Province, Indonesia.

METHODS

Forty-four antibiotic-resistant E. coli isolates from fecal samples from 44 pig farms in Banten Province, Indonesia, were used as samples. The samples were categorized into 14 clusters. Sequencing was performed using the Oxford Nanopore Technologies MinION platform, with barcoding before sequencing with Nanopore Rapid sequencing gDNA-barcoding (SQK-RBK110.96) according to manufacturing procedures. ARG detection was conducted using ResFinder, and the plasmid replicon was determined using PlasmidFinder.

RESULTS

Three phylogenetic leaves of E. coli were identified in the pig farming cluster in Banten Province. The E. coli isolates exhibited potential resistance to nine classes of antibiotics. Fifty-one ARGs were identified across all isolates, with each cluster carrying a minimum of 10 ARGs. The ant(3'')-Ia and qnrS1 genes were present in all isolates. ARGs in the E. coli pig farming cluster originated mainly from plasmids, accounting for an average of 89.4%.

CONCLUSIONS AND RELEVANCE

The elevated potential for MDR events, coupled with the dominance of ARGs originating from plasmids, increases the risk of ARG spread among bacterial populations in animals, humans, and the environment.

The Effects of Poria cocos Polysaccharides on Growth Performance, Immunity, and Cecal Microflora Composition of Weaned Piglets

This paper aims to identify Poria cocos polysaccharides (PCPs) as a potential feed additive used for swine production; thus, we explored the effects of different dietary inclusion levels of PCP on growth performance, immunity, and cecal microflora composition in weaned piglets. For this, a total of 120 28-day-old Duroc × Landrace × Yorkshire weaned piglets (8.51 ± 0.19 kg; 28 ± 1 days of age) were randomly allocated to five groups that were fed a basal diet supplemented with 0, 0.025%, 0.05%, 0.1%, and 0.2% PCP, respectively, for 42 days. The results indicated that the average daily gain (ADG) and gain/feed ratio were higher in the PCP treatment groups than in the control group, with a linear effect. The serum concentrations of IgG, IgA, IL-2, IFN-γ, the number of CD4+ T cells, and the CD4+-to-CD8+ T-cell ratio (CD4+/CD8+) were increased, while the levels of IL-6 and TNF-α were decreased in the PCP supplementation groups compared with those in the control group. Furthermore, the cytokine mRNA expression levels exhibited a similar trend in the spleen. PCP supplementation also reduced the abundance of Escherichia coli and Salmonella and enhanced that of Lactobacilli and Bifidobacteria in the cecum. In summary, dietary PCP inclusion exerted positive effects on the growth performance, immunity, and cecal microbiota of piglets and showed potential for use as a feed additive for improving the health of weaned piglets, with 0.1% being the optimal dosage.

Assessment of Knowledge, Attitude and Practice (KAP) Regarding Antimicrobial Usage and Resistance Among Animal Health Professionals of East Wallaga Zone, Oromiya, Ethiopia

Background

Antimicrobial resistance (AMR) is one of the top global public health and economic threats. The use of antimicrobials (AMs) in animal production is a major contributor to the development of AMR globally. Animal health professionals (AHPs) play a key role in ensuring judicious use of AMs.

Objective

To assess the knowledge, attitude and practice (KAP) of antimicrobial usage (AMU) and AMR among healthcare professionals in Nekemte town, Leka Dulecha and Sibu Sire districts.

Methods

A cross-sectional study was conducted with 120 purposively chosen AHPs residing in the districts and the town. A semi-structured questionnaire consisting of 49 questions was used to ascertain the KAP. The chi-square test (X2) was used to analyze the association between the knowledge score and demographic profile of the study participants.

Results

In the study the overall knowledge of the participants was moderately appreciable, and all participants had positive attitudes toward AMR and appropriate usage. In terms of knowledge of antibiotic use, the majority (93.33%) of the participants correctly answered the statement that antibiotics can kill viruses. About 84.17% of the participants correctly knew that antibiotics killed or stopped the growth of both bad and good bacteria. The majority of the participants (74.17%) always or (25.83%) sometimes rely on usage of antibiotics without a doctor's prescription. It was shown that comparing respondents from Sibu Sire, Leka Dulecha and Nekemte town, the scores of knowledge of AMU were significantly (X2=14.13, p=0.007) different. Most animal healthcare professionals from the Sibu sire have a good knowledge of AMU, and contribute to AMR development.

Conclusion

The study revealed that there was moderate knowledge and positive attitude toward AMU and resistance. This warrants continuing capacity building programs for the professionals on AM usage and resistance, and development of field-friendly disease diagnosis and management tools is essential in the need to reduce AMR.

Effects of oxytetracycline on variation in intracellular and extracellular antibiotic resistance genes during swine manure composting

This research aimed to investigate the alterations in extracellular (eARGs) and intracellular (iARGs) antibiotic resistance genes in response to oxytetracycline (OTC), and unravel the dissemination mechanism of ARGs during composting. The findings revealed both low (L-OTC) and high contents (H-OTC) of OTC significantly enhanced absolute abundance (AA) of iARGs (p < 0.05), compared to CK (no OTC). Composting proved to be a proficient strategy for removing eARGs, while AA of eARGs was significantly enhanced in H-OTC (p < 0.05). OTC resulted in an increase in AA of mobile genetic elements (MGEs), ATP levels, antioxidant and DNA repair enzymes in bacteria in compost product. Structural equation model further demonstrated that OTC promoted bacterial DNA repair and antioxidant enzyme activities, altered bacterial community and enhanced MGEs abundance, thereby facilitating iARGs dissemination. This study highlights OTC can increase eARGs and iARGs abundance, underscoring the need for appropriate countermeasures to mitigate potential hazards.

Structural effects of sulfonamides on the proliferation dynamics of sulfonamide resistance genes in the sequencing batch reactors and the mechanism

Antibiotic resistance genes (ARGs) can be easily promoted by antibiotics, however, the structural effects of antibiotics on the proliferation of ARGs dynamic and the associated mechanisms remain obscure in, especially, activated sludge sequencing batch reactors. In the present study, the effects of 9 sulfonamides (SAs) with different structures on the proliferation dynamic of sulfonamide resistance genes (Suls) in the activated sludge sequencing batch reactors and the corresponding mechanisms were determined (30 days), and the results showed that the largest proliferation value (∆AR) of Suls dynamic for SAs (sulfachloropyridazine) was approximately 2.9 times than that of the smallest one (sulfadiazine). The proliferation of Suls was significantly related to the structural features (minHBint6, SssNH, SHBd and SpMax2_Bhm) that represent the biological activity of SAs. To interpret the phenomenon, a mechanistic model was developed and the results indicated that the biodegradation of SAs (T1/2) rather than conjugative transfer frequency or mutation frequency tends to be the key process for affecting Suls proliferation. T1/2 was proved to be dependent on the interactions between SAs and receptors (Ebinding), the cleavage mode (bond dissociation energy), and the site of nucleophilic assault. Besides, the metagenomic analysis showed that SAs posed significant effect on antibiotic resistome and Tnp31 played a vital role in the proliferation of Suls. Overall, our findings provide important insight into a theoretical basis for understanding the structural effects of SAs on the proliferation of ARGs in SBR systems.

Prevalence, antibiotic susceptibility and genomic analysis of Salmonella from retail meats in Shaanxi, China

Salmonella is a major foodborne pathogen that poses a substantial risk to food safety and public health. This study aimed to assess the prevalence, antibiotic susceptibility, and genomic features of Salmonella isolates recovered from 600 retail meat samples (300 pork, 150 chicken and 150 beef) from August 2018 to October 2019 in Shaanxi, China. Overall, 40 (6.67 %) of 600 samples were positive to Salmonella, with the highest prevalence in chicken (21.33 %, 32/150), followed in pork (2.67 %, 8/300), while no Salmonella was detected in beef. A total of 10 serotypes and 11 sequence types (STs) were detected in 40 Salmonella isolates, with the most common being ST198 S. Kentucky (n = 15), ST13 S. Agona (n = 6), and ST17 S. Indiana (n = 5). Resistance was most commonly found to tetracycline (82.50 %), followed by to ampicillin (77.50 %), nalidixic acid (70.00 %), kanamycin (57.50 %), ceftriaxone (55.00 %), cefotaxime (52.50 %), cefoperazone (52.50 %), chloramphenicol (50.00 %), levofloxacin (57.50 %), cefotaxime (52.50 %), kanamycin (52.50 %), chloramphenicol (50.00 %), ciprofloxacin (50.00 %), and levofloxacin (50.00 %). All ST198 S. Kentucky isolates showed multi-drug resistance (MDR; ≥3 antimicrobial categories) pattern. Genomic analysis showed 56 distinct antibiotic resistance genes (ARGs) and 6 target gene mutations of quinolone resistance determining regions (QRDRs) in 40 Salmonella isolates, among which, the most prevalent ARG types were related to aminoglycosides and β-lactams resistance, and the most frequent mutation in QRDRs was GyrA (S83F) (47.5 %). The number of ARGs in Salmonella isolates showed a significant positive correlation with the numbers of insert sequences (ISs) and plasmid replicons. Taken together, our findings indicated retail chickens were seriously contaminated, while pork and beef are rarely contaminated by Salmonella. Antibiotic resistance determinants and genetic relationships of the isolates provide crucial data for food safety and public health safeguarding.

Genomic traits of multidrug resistant enterotoxigenic Escherichia coli isolates from diarrheic pigs

Diarrhea caused by enterotoxigenic Escherichia coli (ETEC) infections poses a significant challenge in global pig farming. To address this issue, the study was conducted to identify and characterize 19 ETEC isolates from fecal samples of diarrheic pigs sourced from large-scale farms in Sichuan Province, China. Whole-genome sequencing and bioinformatic analysis were utilized for identification and characterization. The isolates exhibited substantial resistance to cefotaxime, ceftriaxone, chloramphenicol, ciprofloxacin, gentamicin, ampicillin, tetracycline, florfenicol, and sulfadiazine, but were highly susceptible to amikacin, imipenem, and cefoxitin. Genetic diversity among the isolates was observed, with serotypes O22:H10, O163orOX21:H4, and O105:H8 being dominant. Further analysis revealed 53 resistance genes and 13 categories of 195 virulence factors. Of concern was the presence of tet(X4) in some isolates, indicating potential public health risks. The ETEC isolates demonstrated the ability to produce either heat-stable enterotoxin (ST) alone or both heat-labile enterotoxin (LT) and ST simultaneously, involving various virulence genes. Notably, STa were linked to human disease. Additionally, the presence of 4 hybrid ETEC/STEC isolates harboring Shiga-like toxin-related virulence factors, namely stx2a, stx2b, and stx2e-ONT-2771, was identified. IncF plasmids carrying multiple antimicrobial resistance genes were prevalent, and a hybrid ETEC/STEC plasmid was detected, highlighting the role of plasmids in hybrid pathotype emergence. These findings emphasized the multidrug resistance and pathogenicity of porcine-origin ETEC strains and the potential risk of epidemics through horizontal transmission of drug resistance, which is crucial for effective control strategies and interventions to mitigate the impact on animal and human health.

Enhancing the Antibiotic Production by Thermophilic Bacteria Isolated from Hot Spring Waters via Ethyl Methanesulfonate Mutagenesis

Antibiotic-resistant bacteria represent a serious public health threat. For that reason, the development of new and effective antibiotics to control pathogens has become necessary. The current study aims to search for new microorganisms expressing antibiotic production capacity. Fifteen sites covering a wide range of harsh environmental conditions in Egypt were investigated. Two hundred and eighty bacterial isolates were obtained and then tested against pathogenic bacteria using the agar disk diffusion technique. Fifty-two (18.6% of the total) of the isolates exhibited antagonistic properties, which affected one or more of the tested pathogens. The isolate 113 was identified as Bacillus licheniformis and isolate 10 was identified as Brevibacillus borstelensis using the 16S rRNA technique. The B. licheniformis strain was stronger in antibiotic production against S. typhi, M. luteus, and P. ariginosa, whereas the strain Br. borstelensis was more efficient against B. cereus, E. coli, and Klebs. sp. The sensitivity of the strains to commercial antibiotics showed that B. licheniformis was highly sensitive to seven commercial antibiotics, whereas Br. borstelensis was sensitive to nine antibiotics. The two strains were subjected to ethyl methanesulfonate (EMS) mutagenesis to obtain mutants with a higher antibiotic production. The total bacterial count was measured after treatment with EMS mutagen and showed a significant gradual increase in the antimicrobial activity, which was achieved via shaking in the presence of EMS for 60 min. High antimicrobial activities were noted with 17 and 14 mutants from the B. licheniformis and Br. borstelensis strains, respectively. The mutant B. licheniformis (M15/Amo) was more active than the parent strain against S. aureus (212.5%), while the mutant Br. borstelensis (B7/Neo) was more effective against S. typhi (83.3%). The present study demonstrates the possibility of obtaining potent antibiotic-producing bacteria in hot spring waters and further improving the indigenous bacterial capacity to produce antibiotics by using EMS mutagenesis.

Ligilactobacillus salivarius MP100 as an Alternative to Metaphylactic Antimicrobials in Swine: The Impact on Production Parameters and Meat Composition

The metaphylactic use of antimicrobials in swine farms contributes to the emergence of antibiotic-resistant bacteria, which constitutes a major challenge for public health. Alternative strategies are required to eradicate their routine use. In a previous study, metaphylactic antimicrobials were replaced by the administration of Ligilactobacillus salivarius MP100 to sows and piglets for two years. This practice positively modified the fecal microbiota and metabolic profiles in the farm. In this work, the farm dataset was used to compare the productivity-related parameters between a 2-year period of routine metaphylactic antibiotherapy and the first 2 years of a replacement with the probiotic strain. The probiotic period improved these productivity-related parameters, from litter size to growth performance. In addition, samples of Longissimus lumborum, including skin and subcutaneous fat, were obtained from the animals ingesting the probiotic strain and controls (metaphylactic antibiotherapy) and analyzed for their pH, water holding capacity, composition, and metabolic profiling. The probiotic intake did not negatively affect the meat composition and was associated with an increase in inosine concentration and a slight tendency for increasing the intramuscular fat content. These factors are considered as biomarkers of meat quality. In conclusion, the substitution of metaphylactic antimicrobials with the administration of the probiotic strain was associated with beneficial productivity and meat quality outcomes.

Genomic epidemiology and transmission characteristics of mcr1-positive colistin-resistant Escherichia coli strains circulating at natural environment

MCR-positive Escherichia coli (MCRPEC) have been reported in humans worldwide. The high prevalence of mcr-1 poses clinical and environmental risks due to its diverse genetic mechanisms. Given the vital role of animals and the environment in the spread of antibiotic resistance, a "One Health" perspective should be taken when addressing antimicrobial resistance issues. This study conducted a prospective study in six farms (located in Jiaxing City, Zhejiang province, China) in 2019. MCRPEC strains were screened from samples of different sources. The molecular epidemiological surveys and transmission potential were investigated by whole-genome sequencing and phylogenetic analysis. MCRPEC were detected in different farms with various sources. Sequence type complex 10 was dominant and distributed widely in multiple sources. Core-genome multilocus sequence type (cgMLST) analysis indicated that clonal transmission could occur within and between farms. In addition, mcr-1 genes with different locations showed different transmission tendencies. The study indicated that interspecies and cross-regional transmission of MCRPEC could occur between different sectors in farms. Further surveillance and research of non-clinical MCRPEC strains are necessary to reduce the threat of MCRPEC.

Characterization and genome analysis of a novel phage Kayfunavirus TM1

Escherichia coli is a common conditional pathogen, for which antibiotic therapy is considered an effective treatment. The imprudent use of antibiotics has led to the increase of multiple-antibiotic-resistant E. coli species. With the incidence of antibiotic resistance reaching a crisis point, it is imperative to find alternative treatments for multidrug-resistant infections. Using phage for pathogen control is a promising treatment option to combat bacterial resistance. In this study, a novel virulent Podoviridae phage Kayfunavirus TM1 infecting Escherichia coli was isolated from pig farm sewage in Guangxi, China. The one-step growth curve with the optimal multiplicity of infection of 0.01 revealed a latent period of 10 min and a burst size of 50 plaque-forming units per cell. The stability test reveals that it is stable from 4 to 60 °C and pH from 3 to 11. The double-stranded DNA genome of phage Kayfunavirus TM1 is composed of 39,948 base pairs with a GC content of 50.03%.

Colistin resistance and resistance determinants are mobile among Salmonella enterica isolates from diseased and healthy pigs in Thailand

Salmonella is an important enteric pathogen that poses a threat to human and livestock animal health, with emerging multidrug resistance (MDR) a major public health issue globally. We investigated the prevalence of Salmonella in healthy and diseased pigs from Thai pig farms and determined their phenotypic and genotypic antimicrobial resistance profiles. A total of 150 fecal samples were collected from pigs housed in pens from four separate pig farms in southern Thailand and tested for the presence of Salmonella. Confirmed Salmonella isolates were tested for their susceptibility to 11 antimicrobials, and PCR used to detect known antimicrobial resistance genes (ARGs). Salmonella isolates were cultured from 69% (103/150) of all fecal samples, with higher prevalence in disease pigs (12/15; 80%), compared with healthy pigs (91/135; 67%). Serotype Rissen was the most frequently identified serotype among the Salmonella isolates. Resistance to ampicillin (AMP) (97%), sulfonamide-trimethoprim (SXT) (97%), and tetracycline (TET) (94%) were the most common phenotypes observed. The most common ARGs identified were blaTEM gene (99.%), tetA (87%), sul1 (77%), and dfrA1 (74%), and more than 95% of the Salmonella isolates tested were MDR - based on resistance to three or more antimicrobial classes. The most common antimicrobial resistance pattern exhibited was AMP-TET-SXT (76%), and resistance to colistin (via the mcr-1 gene) was observed in both healthy and diseased pigs. The clonal groups of PFGE analysis in serotype Typhimurium revealed the genetic relationship among Salmonella isolated from healthy and diseased pigs from different pig farms.

The challenges of pig farming in Hong Kong: a study of farmers' perceptions and attitudes towards a pig health and production management service

BACKGROUND

Pig farming in Hong Kong differs markedly from other places in the world, with a highly urbanised population, the majority of pigs being imported for slaughter, and limited on-farm veterinary support. Little is known about the barriers and attitudes of pig farmers in Hong Kong and their expectations of a new pig health and production management service provided by veterinarians. We collected qualitative and quantitative data to 1) describe pig farms, 2) identify barriers to pig farming in Hong Kong and 3) describe the perceptions of the new service. Thematic analysis was conducted to identify barriers and attitudes.

RESULTS

Eight and nine out of 38 pig farmers agreed to participate in the qualitative and quantitative components, respectively. All farms were farrow-to-finish farms with a median of 2800 (range 950 to 7000) pigs per farm. Three themes were identified during the interview analysis and could be ranked based on their importance to the farmers: the regulatory environment (Theme 1), veterinary support structures (Theme 2), and the sustainability of the pig industry (Theme 3). Farmers expressed dissatisfaction with the regulation of the industry and veterinary services on offer within Hong Kong. However, farmers did note that the provision of a new pig health and production management service was as a positive development. The public perception of pig farming, market forces, and competition from mainland pig farmers have resulted in sustainability challenges for the industry.

CONCLUSIONS

Farmers identified very specific local systems and challenges unique to pig farming in Hong Kong. The lack of veterinary support was one of these challenges and although a certain level of scepticism towards the new pig health and production service was expressed, farmers indicated their interest and listed areas where they would benefit from improved veterinary support. Prior experiences of veterinary services clouded farmers perceptions of the usefulness of a new service. To be successful in this environment, clear communication about the goals, role and limitations of the new on farm service is crucial, as is the alignment with the needs of farmers. Despite the small sample size, the qualitative methodology used allows us to assume that these themes give a general idea of what Hong Kong farmers' concerns and attitudes are.

The Diversity of Escherichia coli Pathotypes and Vaccination Strategies against This Versatile Bacterial Pathogen

Escherichia coli (E. coli) is a gram-negative bacillus and resident of the normal intestinal microbiota. However, some E. coli strains can cause diseases in humans, other mammals and birds ranging from intestinal infections, for example, diarrhea and dysentery, to extraintestinal infections, such as urinary tract infections, respiratory tract infections, meningitis, and sepsis. In terms of morbidity and mortality, pathogenic E. coli has a great impact on public health, with an economic cost of several billion dollars annually worldwide. Antibiotics are not usually used as first-line treatment for diarrheal illness caused by E. coli and in the case of bloody diarrhea, antibiotics are avoided due to the increased risk of hemolytic uremic syndrome. On the other hand, extraintestinal infections are treated with various antibiotics depending on the site of infection and susceptibility testing. Several alarming papers concerning the rising antibiotic resistance rates in E. coli strains have been published. The silent pandemic of multidrug-resistant bacteria including pathogenic E. coli that have become more difficult to treat favored prophylactic approaches such as E. coli vaccines. This review provides an overview of the pathogenesis of different pathotypes of E. coli, the virulence factors involved and updates on the major aspects of vaccine development against different E. coli pathotypes.

Mannan based prebiotics modulate growth rate and energy phenotype of tetracycline resistant E. coli

Unsustainable antimicrobial use in industrial agriculture has contributed to the rise in antimicrobial resistance and there is an urgent need to find alternative and more sustainable strategies to traditional antimicrobials. Prebiotics, such as mannan-rich fraction (MRF), a cell wall product from Saccharomyces cerevisiae, have demonstrated an ability to alter the growth of antibiotic susceptible and resistant Escherichia coli and improve the efficacy of antibiotics through modulation of cellular activity. In this study the impact of mannan based prebiotics on growth and respiration of E. coli was assessed by observing microbial growth, oxygen consumption rate and extracellular acidification rate in the presence and absence of tetracycline. The findings further demonstrate the capabilities of MRF with respect to improving microbial antibiotic sensitivity, particularly in resistant strains. This potentially enables a more efficient control of resistant pathogens with food safety implications and promotion of more sustainable use of antibiotics in animal production systems.

Comparative Genome Analysis of 19 Trueperella pyogenes Strains Originating from Different Animal Species Reveal a Genetically Diverse Open Pan-Genome

Trueperella pyogenes is a Gram-positive opportunistic pathogen that causes severe cases of mastitis, metritis, and pneumonia in a wide range of animals, resulting in significant economic losses. Although little is known about the virulence factors involved in the disease pathogenesis, a comprehensive comparative genome analysis of T. pyogenes genomes has not been performed till date. Hence, present investigation was carried out to characterize and compare 19 T. pyogenes genomes originating in different geographical origins including the draftgenome of the first Indian origin strain T. pyogenes Bu5. Additionally, candidate virulence determinants that could be crucial for their pathogenesis were also detected and analyzed by using various bioinformatics tools. The pan-genome calculations revealed an open pan-genome of T. pyogenes. In addition, an inventory of virulence related genes, 190 genomic islands, 31 prophage sequences, and 40 antibiotic resistance genes that could play a significant role in organism's pathogenicity were detected. The core-genome based phylogeny of T. pyogenes demonstrates a polyphyletic, host-associated group with a high degree of genomic diversity. The identified core-genome can be further used for screening of drug and vaccine targets. The investigation has provided unique insights into pan-genome, virulome, mobiliome, and resistome of T. pyogenes genomes and laid the foundation for future investigations.

Qualitative analysis of trace quinolone antibiotics by SERS with fine structure dependent sensitivity

Antibiotics are widely used in daily life, which has created a global scenario where many pathogenic organisms have become effectively resistant to antibiotics. The abuse or overuse of antibiotics causes significant environmental pollution and even endangers human health. It is well-known that antibiotics' efficacy (toxicity) is determined by molecular structure. Therefore, structure-level qualitative analysis with high sensitivity and accuracy is vitally important. Characterized by fingerprinting recognition, Raman spectroscopy, especially surface-enhanced Raman spectroscopy (SERS), has become an essential qualitative analysis tool in various fields, such as environmental monitoring and food safety. With the exception of chirality, this study completed the qualitative trace analysis of 16 quinolone antibiotics (QNs) with fine molecular structure differences using SERS. The sensitivity was tuned in by one order of magnitude through the different electronegativity and steric hindrances of the slightly changed functional groups in the specific antibiotics. The fine structure dependent sensitivity enables SERS to be a powerful on-site monitoring tool to control the abuse of antibiotics with high toxicity; thus, decreasing the subsequent risk to the environmental ecology and human society.

Dynamic antimicrobial resistant patterns of Escherichia coli from healthy poultry and swine over 10 years in Chongming Island, Shanghai

Background

Antimicrobial resistance (AMR) is one of the greatest threats to animal and public health. Here, we conducted a dynamic surveillance of Escherichia coli on Chongming Island in Shanghai during 2009–2021 to identify the characteristics and trends of Chongming’s AMR pandemic.

Methods

Rectal (cloaca) swabs from four poultry and nine swine farms (Chongming Island, 2009–2021) were collected for E. coli strains acquisition. The micro-broth dilution method was used to test antimicrobial susceptibility of E. coli isolates against 10 antimicrobial classes including 15 antimicrobials. Utilizing generalized linear mixed models (GLMMs) and co-occurrence analyses, we further explored the multiple-drug-resistance (MDR) combinations and dynamic patterns of E. coli over 10 years in two food animals.

Results

Total of 863 MDR isolates were found among 945 collected E. coli isolates, 337 from poultry and 608 from swine. Both isolates exhibited high resistant rates (> 70%) to tetracyclines, phenicols, sulfonamides, penicillins, and aminoglycosides (only in swine). The resistant rates of swine isolates to penicillins, aminoglycosides, tetracyclines, phenicols, and polymyxins were significantly higher than those of poultry isolates, whereas resistance to fluoroquinolones was reversed. Resistance to polymyxins decreased similarly in swine (42.4% in 2009 to 0.0% in 2021) and poultry isolates (from 16.5% to 0.0%). However, resistance to other seven antimicrobial classes (excluding carbapenems and penicillins) declined dramatically in swine isolates, particularly fluoroquinolones (from 80.5% to 14.4%), and tendencies of resistance to the seven classes showed markedly divergent patterns in poultry isolates. Using Poisson GLMMs, the AMR carriage since 2016 was significantly lower than that of 2009 (odds ratio < 1), indicating a decline in the risk of MDR emergence. Furthermore, despite the highly diverse MDR profiles, co-occurrence analysis identified two prominent MDR clusters of penicillins-phenicols-fluoroquinolones in poultry and aminoglycosides-tetracyclines-sulfonamides-phenicols in swine.

Conclusions

Our study uncovered vastly distinct AMR patterns and dynamic tendencies of poultry and swine E. coli isolates from Chongming. Meanwhile, Chongming’s AMR status has ameliorated, as indicated by the decline in antimicrobials prevalence (particularly in swine), lower likelihood of MDR emergence and low carbapenem-, cephalosporin-, and polymyxin resistance. Importantly, this surveillance results are the vital basis for future policy development in Chongming and Shanghai.

Graphical Abstract

Supplementary Information

The online version contains supplementary material available at 10.1186/s40249-022-01025-4.

Substrate complexity affects the prevalence and interconnections of antibiotic, metal and biocide resistance genes, integron-integrase genes, human pathogens and virulence factors in anaerobic digestion

Anaerobic digestion (AD) is widely used to treat livestock manure that harbors diverse pollutants (resistance genes (ARGs), metal/biocide resistance genes (MBRGs), integron-integrase genes, human pathogens and pathogen virulence factors (VFs)). However, the interplays of these pollutants and the effects of substrate complexity on pollutants in AD are elusive. This study investigated the dynamics of these pollutants and bacterial communities during AD of swine manure, by metatranscriptomic sequencing and amplicon sequencing of 16 S rRNA and 16 S rRNA gene. The pollutant profiles and bacterial communities differed across AD processes, nevertheless with consistent dominance of ARGs of multi-drugs, tetracycline, aminoglycoside and rifamycin, MBRGs of multi-biocides, multi-metals, copper and arsenic, the integron-integrase gene intI1, potential pathogens of Escherichia coli, Streptococcus gallolyticus and Clostridium perfringens, VFs involved in pathogen adherence, and bacterial phyla of Firmicutes, Bacteroidetes and Proteobacteria. Reduced substrate complexity (replacing a part of swine manure, a complex substrate, with a simple substrate, apple waste or fructose) decreased the prevalence and stochastic turnover of ARGs and MBRGs. Network analyses revealed decreased interplays among pollutants under reduced substrate complexity. Our findings provide a mechanical understanding of diverse pollutants dynamics during AD, and reveal the importance of substrate complexity in controlling prevalence and interplays of pollutants.

Ecotoxicological effects of untreated pig manure from diets with or without growth-promoting supplements on Eisenia andrei in subtropical soils

This study aimed to evaluate the effects of untreated pig manure from diets incorporating growth-promoting supplements (antibiotics and Zn oxide) on the survival and reproduction of Eisenia andrei earthworms. The tested manures were obtained from four different groups of pigs fed with four different diets: CS, a diet based on corn and soymeal; TR, a diet based on corn, soymeal, and ground wheat (15%); CSa, a diet based on corn and soymeal + 100 ppm of doxycycline + 50 ppm of colistin + 2500 ppm of Zn oxide; and TRa, a diet based on corn, soymeal, and ground wheat (15%) + 100 ppm of doxycycline + 50 ppm of colistin + 2500 ppm of Zn oxide. The study used two soils representative of the Southern region of Brazil (Oxisol and Entisol). In general, there were no significant differences between the different manures tested in each soil. However, there were differences in the toxicity manure on E. andrei between the soils, and the magnitude of this effect was dependent on the applied dose. In Oxisol, LC₅₀ values were higher than 80 m³ ha^-1, and EC₅₀ varied from 9 to 27 m³ ha^-1. In Entisol, the LC₅₀ values were below the lowest dose tested (< 25 m³ ha^-1), and EC₅₀ remained around 5 m³ ha^-1. It may be possible that the effects observed were attributed to an excess of nitrogen, copper, and zinc, promoted by the addition of the untreated manure and how these factors interacted with soil type.

Phytotoxicity of environmental norfloxacin concentrations on the aquatic plant Spirodela polyrrhiza: Evaluation of growth parameters, photosynthetic toxicity and biochemical traits

As an emerging pollutant, the increasing use of antibiotics in wastewater posed a serious threat to non-target organisms in the environment. Duckweed (Spirodela polyrrhiza) is a common higher aquatic plant broadly used in phytotoxicity tests for xenobiotic substances. The aim of this study was to evaluate the chronic toxicity of norfloxacin (NOR) on Spirodela polyrrhiza during 18 days of exposure. Our study investigated the addition of NOR into the medium with environment-related concentrations (0, 0.1, 10, and 1000 μg L^-1). Subsequently, biomarkers of toxicity such as growth, pigment, chlorophyll fluorescence parameters, indicators of oxidative stress, and osmotic regulatory substances content were analyzed in duckweed. In response to NOR exposure, obvious chlorosis, declines in growth and photosynthetic pigment, and photosystem II inhibition were noted in a concentration dependent manner. Reactive oxygen species (ROS) and antioxidant activity content increased in the treated fronds, which indicated that oxidative stress was specifically affected by NOR exposure. A slight increase in osmotic regulatory substances in NOR treated setups than in the control represented the increasing stress resistance. These results suggest NOR exerts its toxic effects on the aquatic plant Spirodela polyrrhiza.

Identification of a broad-spectrum lytic Myoviridae bacteriophage using multidrug resistant Salmonella isolates from pig slaughterhouses as the indicator and its application in combating Salmonella infections

Background

Salmonella is a leading foodborne and zoonotic pathogen, and is widely distributed in different nodes of the pork supply chain. In recent years, the increasing prevalence of antimicrobial resistant Salmonella poses a threat to global public health. The purpose of this study is to the prevalence of antimicrobial resistant Salmonella in pig slaughterhouses in Hubei Province in China, and explore the effect of using lytic bacteriophages fighting against antimicrobial resistant Salmonella.

Results

We collected a total of 1289 samples including anal swabs of pigs (862/1289), environmental swabs (204/1289), carcass surface swabs (36/1289) and environmental agar plates (187/1289) from eleven slaughterhouses in seven cities in Hubei Province and recovered 106 Salmonella isolates. Antimicrobial susceptibility testing revealed that these isolates showed a high rate of antimicrobial resistance; over 99.06% (105/106) of them were multidrug resistant. To combat these drug resistant Salmonella, we isolated 37 lytic phages using 106 isolates as indicator bacteria. One of them, designated ph 2–2, which belonged to the Myoviridae family, displayed good capacity to kill Salmonella under different adverse conditions (exposure to different temperatures, pHs, UV, and/or 75% ethanol) and had a wide lytic spectrum. Evaluation in mouse models showed that ph 2–2 was safe and saved 80% (administrated by gavage) and 100% (administrated through intraperitoneal injection) mice from infections caused by Salmonella Typhimurium.

Conclusions

The data presented herein demonstrated that Salmonella contamination remains a problem in some pig slaughter houses in China and Salmonella isolates recovered in slaughter houses displayed a high rate of antimicrobial resistance. In addition, broad-spectrum lytic bacteriophages may represent a good candidate for the development of anti-antimicrobial resistant Salmonella agents.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12917-022-03372-8.

Molecular Evolution and Genomic Insights into Community-Acquired Methicillin-Resistant Staphylococcus aureus Sequence Type 88

Sequence type 88 (ST88) methicillin-resistant Staphylococcus aureus (MRSA) has been recognized as an important pathogen that causes infections in humans, especially when it has strong biofilm production and multidrug resistance (MDR). However, knowledge of the determinants of resistance or virulence and genomic characteristics of ST88 MRSA from China is still limited. In this study, we employed the antimicrobial resistance (AMR), biofilm formation, and genomic characteristics of ST88 MRSA collected from various foods in China and estimated the worldwide divergence of ST88 MRSA with publicly available ST88 genomes. All ST88 isolates studied were identified as having resistance genes, while 50% (41/82) harbored MDR genes. All isolates carried core virulence genes related to immune modulation, adherence, secreted enzymes, and hemolysin. In addition, all 20 Chinese ST88 isolates showed biofilm production capacity, three strongly so. Bayesian phylogenetic analysis showed that Chinese ST88 clones formed an independent MRSA lineage, with two subclades associated with acquisition of type IVc staphylococcal cassette chromosome mec (SCCmec) elements. In contrast, all African ST88 strains were subtyped as SCCmecIVa, where the African clades were mixed with a few European and American isolates, suggesting potential transmission from Africa to these regions. In summary, our results revealed the evolution of ST88 MRSA in humans, animals, and foods in Africa and Asia. The food-associated ST88 genomes in this study will remedy the lack of food-associated ST88 isolates, and the study in general will extend the discussion of the potential exchanges of ST88 between humans and foods or food animals.

IMPORTANCE ST88 MRSA has frequently been detected in humans, animals, and foods mainly in Africa and Asia. It can colonize and cause mild to severe infections in humans, especially children. Several studies from African countries have described its genotypic characteristics but, limited information is available on the evolution and characterization of ST88 MRSA in Asia, especially China. Meanwhile, the molecular history of its global spread remains largely unclear. In this study, we analyzed the genomic evolution of global ST88 MRSA strains in detail and identified key genetic changes associated with specific hosts or regions. Our results suggested geographical differentiation between ST88 MRSA’s evolution in Africa and its evolution in Asia, with a more recent clonal evolution in China. The introduction of ST88 MRSA in China was aligned with the acquisition of SCCmecIVc elements, specific virulent prophages, and AMR genes.

The Multi-Omics Analysis Revealed Microbiological Regulation of Rabbit Colon with Diarrhea Fed an Antibiotic-Free Diet

Diarrhea symptoms appeared after antibiotics were banned from animal feed based on the law of the Chinese government in 2020. The colon and its contents were collected and analyzed from diarrheal and healthy rabbits using three omics analyses. The result of the microbial genomic analysis showed that the abundance of Bacteroidetes and Proteobacteria increased significantly (p-value < 0.01). Transcriptomes analysis showed that differentially expressed genes (DEGs) are abundant in the IL-17 signaling pathway and are highly expressed in the pro-inflammatory pathway. The metabolome analysis investigated differential metabolites (DMs) that were mainly enriched in tryptophan metabolism and bile secretion, which were closely related to the absorption and immune function of the colon. The results of correlation analysis showed that Bacteroidetes was positively correlated with 4-Morpholinobenzoic acid, and 4-Morpholinobenzoic acid could aggravate inflammation through its influence on the bile secretion pathway. The enriched DMs L-Tryptophan in the tryptophan metabolism pathway will lead to the functional disorder of inhibiting inflammation by affecting the protein digestion and absorption pathway. Thus, the colonic epithelial cells were damaged, affecting the function of the colon and leading to diarrhea in rabbits. Therefore, the study provided an idea for feed development and a theoretical basis for maintaining intestinal tract fitness in rabbits.

Students Against Superbugs (SAS) Africa

Antimicrobial resistance is a major worldwide health problem that develops when antibiotics used to treat illnesses become ineffective due to the emergence of drug-resistant bacteria (superbugs). This is a significant issue that demands immediate intervention. Students Against Superbugs Africa wants to educate young people about the dangers of antibiotic resistance and the need of prevention. This is done through a variety of programs, including virtual and physical stewardship activities, research and innovation, community engagement, drug research and development, participation in World Antimicrobial Awareness Week, the AMR gamification program, the AMR writers and content creators' program, and the "know something about antimicrobial resistance" project.

Effects of Taraxacum mongolicum Hand.-Mazz. (dandelion) on growth performance, expression of genes coding for tight junction protein and mucin, microbiota composition and short chain fatty acids in ileum of broiler chickens

Background

Dandelion is becoming an exploitable alternative to the widely prohibited antibiotics in the poultry production. This research aimed to investigate the effects of dandelion on the growth performance and intestinal barrier function of broiler chickens maintained under standard condition of management. One-hundred and sixty 1-day-old Arbor Acres (AA) male broiler chickens were randomly divided into four groups, with five replicates of eight birds each. The birds were fed a basal diet supplemented without (control group, [CON]) or with 500 (low dose [LD]) or 1000 (high dose [HD]) mg/kg dandelion or with 250 mg/kg chlortetracycline 20% premix (CTC) for 42 days, including the starter phase (d 1 to 21) and the grower phase (d 22 to 42). Body weight (BW) of each bird and feed consumption of each replicate were measured at d 21 and d 42. The ileal tissues were collected on day 21 and 42 to determine expression of genes coding for tight junction protein and mucin as well as ELISA analysis for immune factor. The ileal digesta was collected for microbiota and short chain fatty acids analysis.

Results

Compared with CON group, during day 1–21, the average daily feed intake (ADFI) and feed/gain ratio (F/G) of LD group were lower (P < 0.05); during day 22–42, the F/G of LD and CTC group tended to be lower (P = 0.07); during the overall phase, the ADFI of HD and CTC groups were decreased (P < 0.05), and the F/G of dandelion and CTC groups tended to be decreased (P = 0.07). On day 21, the relative mRNA expression of claudin, occludin-1 and mucin1 in dandelion groups were up-regulated (P < 0.05), and the ZO-1 mRNA expression in CTC group was increased (P < 0.05); on day 42, the claudin and mucin1 transcripts in LD group and ZO-1 transcripts in HD and CTC group were up-regulated (P < 0.05), while the occludin-1 and mucin1 transcripts in CTC group was significantly down-regulated (P < 0.05). In addition, the contents of TNF-α in dandelion groups were lower than that in CTC group (P < 0.05). In the analysis of ileal microbiota, on day 21, decreased α-diversity was observed in HD and CTC groups (P < 0.05). Meanwhile, on day 21, the relative abundance of Firmicutes in dandelion groups tended to be higher (P = 0.09), the relative abundance of Lactobacillus in LD and CTC group were increased (P < 0.05), while Bacteroidete, Bacteroides, and Alistipes relative abundance in dandelion and CTC groups were decreased (P < 0.05). On day 42, the Actinobacteriota relative abundance in CTC group tended to be higher (P = 0.05), and Lysinibacillus relative abundance of CTC group was higher (P = 0.02). Compared with CON group, on day 21, the propionic acid and butyric acid content in CTC group were higher, the butyric acid content in HD group was lower (P < 0.10).

Conclusion

In summary, dietary dandelion supplementation at 500 mg/kg of diet enhanced growth performance of broilers by improving the intestinal barrier function. Dandelion can be supplemented in the diet as an antibiotics alternative to enhance production in poultry industry.

Dissecting the Effect of Berberine on the Intestinal Microbiome in the Weaned Piglets by Metagenomic Sequencing

This study aimed to investigate the microbial structure and function in the rectum of weaned piglets with berberine supplementation. Twelve healthy 21-day-old Duorc × (Landrace × Large White) weaned piglets (similar body weight) were evenly divided into control and berberine groups and were fed a basal diet supplemented with 0 and 0.1% berberine, respectively. After 21 days, metagenomic sequencing analysis was performed to detect microbial composition and function in the rectum of weaned piglets. Results showed that there were 10,597,721,931–14,059,392,900 base pairs (bp) and 10,186,558,171–15,859,563,342 bp of clean data in the control and berberine groups, respectively. The Q20s of the control and berberine groups were 97.15 to 97.7% and 96.26 to 97.68%, respectively. The microorganisms in the berberine group had lower (p < 0.05) Chao1, alternating conditional expectation, Shannon, and Simpson indices at the species levels than those in the control group. Analysis of similarity showed that there were significant differences (p < 0.01) between the control and berberine groups at the genus and species levels of the gut microorganisms. Dietary berberine significantly increased (p < 0.05) the abundance of Subdoligranulum variabile, but decreased (p < 0.05) the abundance of Prevotella copri compared with the control group. Carbohydrate-active enzymes analysis revealed that the levels of polysaccharide lyases and carbohydrate esterases were lower (p < 0.05) in the berberine group than that in the control group. Linear discriminant analysis effect size analysis showed that berberine supplementation could induce various significant Kyoto Encyclopedia of Genes and Genomes pathways, including carbohydrate metabolism, environmental information processing, and microbial metabolism in diverse environments. In conclusion, our findings suggest that berberine could improve the composition, abundance, structure, and function of gut microbiome in the weaned piglets, potentially providing a suitable approach for the application of berberine in human and animal health.

Effects of Immobilized Antimicrobial Peptides on Growth Performance, Serum Biochemical Index, Inflammatory Factors, Intestinal Morphology, and Microbial Community in Weaning Pigs

This experiment was conducted to investigate the effects of immobilized antimicrobial peptides on growth performance, serum biochemical index, inflammatory factors, intestinal morphology, and microbial community of weaning piglets. A total of 21 weaning piglets [Duroc × (Landrace × Yorkshire)] with initial body weight (7.64 ± 0.65 kg) were randomly allocated to one of three treatments with seven replicates (one pig per replicate) per treatment according to sex and weight in randomized complete block design. Pigs in the three treatments were fed corn–soybean meal-based diet (CON), corn–soybean meal based diet + flavomycin (25 mg/kg) + quinone (50 mg/kg) (AB), and corn–soybean meal based diet + 1,000 mg/kg immobilized antimicrobial peptides (IAMPs), respectively. The experiment lasted for 28 days, including early stage (0–14 days) and late stage (15–28 days). The results showed the following: (1) compared with the CON group, the average daily gain in the whole experimental time (p < 0.05) was significantly increased, and the diarrhea rate of weaning piglets was decreased (p < 0.01) in the IAMPs group; (2) compared with the CON group, the concentrations of serum IgM and superoxide dismutase (SOD) in the IAMPs group were significantly higher than the CON and AB groups (p < 0.01); (3) compared with CON group, the concentrations of serum interleukin (IL)-10 and transforming growth factor (TGF-β) were significantly increased (p < 0.05), and the concentration of IL-12 was significantly decreased (p < 0.05) in the IAMPs group; (4) compared with CON group, the concentrations of serum endotoxin and D-lactate of piglets were significantly reduced (p < 0.05), and the relative expression of ZO-1 and occludin in the jejunum of piglets were significantly increased (p < 0.05) in the IAMPs group; (5) compared with the CON group, the villus height of the duodenum and jejunum of weaning piglets in IAMPs and AB groups was significantly increased (p < 0.05); and (6) compared with CON group, the relative abundance of Escherichia–Shigella in the colon and cecal digesta was decreased. In summary, the addition of 1,000 mg/kg immobilized antimicrobial peptides in the diet effectively relieved weaning stress by showing improved growth performance, antioxidant and immune capacity, intestinal morphology, and microorganisms.

Antimicrobial resistance and population genomics of multidrug-resistant Escherichia coli in pig farms in mainland China

The expanding use of antimicrobials in livestock is an important contributor to the worldwide rapid increase in antimicrobial resistance (AMR). However, large-scale studies on AMR in livestock remain scarce. Here, we report findings from surveillance of E. coli AMR in pig farms in China in 2018–2019. We isolated E. coli in 1,871 samples from pigs and their breeding environments, and found AMR in E. coli in all provinces in mainland China. We detected multidrug-resistance in 91% isolates and found resistance to last-resort drugs including colistin, carbapenems and tigecycline. We also identified a heterogeneous group of O-serogroups and sequence types among the multidrug-resistant isolates. These isolates harbored multiple resistance genes, virulence factor-encoding genes, and putative plasmids. Our data will help to understand the current AMR profiles of pigs and provide a reference for AMR control policy formulation for livestock in China.

Use of antimicrobials in livestock contributes to development of antimicrobial resistance but there are few large-scale surveillance studies. Here, the authors describe E. coli surveillance in pig farms in China, reporting high levels of multidrug-resistance across all mainland provinces.

Effect of Dietary Bacillus licheniformis Supplementation on Growth Performance and Microbiota Diversity of Pekin Ducks

This experiment was conducted to investigate the effects of different concentrations of Bacillus licheniformis (B. licheniformis) on growth performance and microbiota diversity of Pekin ducks. Three hundred 1-day-old healthy Pekin ducks were randomly divided into 5 groups with 6 replicates per group and 10 ducks per replicate. The five treatments supplemented with basal diets containing: either 0 (group CON), 200 (group LLB), 400 (group MLB), and 800 (group HLB) mg/kg B. licheniformis or 150 mg/kg aureomycin (group ANT) for 42 days, respectively, and were sacrificed and sampled in the morning of the 42nd day for detection of relevant indexes. The results showed as follows: The feed conversion ratio of the LLB group and MLB groups were lower than the CON group (P < 0.05). The body weight and average daily feed intake of the MLB group were significantly higher than that of the CON group and ANT group (P < 0.05). Compared with the CON group, the MLB group significantly increased the content of IgA (P < 0.05) and proinflammatory IL-6 were significantly decreased (P < 0.05), besides, the activity of SOD and T-AOC were also significantly increased in the MLB group (P < 0.05). The 16S rRNA analysis showed that B. licheniformis treatments had no effect (P > 0.05) on the alpha diversities of the intestine. The addition of B. licheniformis had a dynamic effect on the abundance of cecal microflora of Pekin ducks, and 1-21 d increased the diversity of microflora, while 21d-42 d decreased it. Compared with the CON group, the relative abundance of Epsilonbacteraeota in the MLB group was significantly increased on Day 21 (P < 0.05), and that of Tenericutes in the LLB group was significantly increased as well (P < 0.05). At 42 d, the relative abundance of Bacteroidetes in LLB, MBL, HBL, and ANT groups was significantly increased (P < 0.05). In addition, the addition of B. licheniformis increased the amount of SCAF-producing bacteria in the intestinal microbiota, such as Lachnospiraceae, Collinsella, Christensenellaceae, and Bilophila. The PICRUSt method was used to predict the intestinal microbiota function, and it was found that lipid transport and metabolism of intestinal microbiota in the MLB group were significantly affected. Overall, these results suggest diet supplemented with B. licheniformis improved growth performance, immune status, antioxidant capacity, and modulated intestinal microbiota in Pekin ducks. The optimal dietary supplement dose is 400 mg/kg.

Superiority of Microencapsulated Essential Oils Compared With Common Essential Oils and Antibiotics: Effects on the Intestinal Health and Gut Microbiota of Weaning Piglet

Essential oils (EOs) have long been considered an alternative to antibiotics in the breeding industry. However, they are unstable and often present unpleasant odors, which hampers their application. Microencapsulation can protect the active gradients from oxidation and allow them to diffuse slowly in the gastrointestinal tract. The purpose of this study was to investigate the effect of microencapsulation technology on the biological function of EOs and the possibility of using microencapsulate EOs (MEEOs) as an alternative to antibiotics in weaning piglets. First, we prepared MEEOs and common EOs both containing 2% thymol, 5% carvacrol and 3% cinnamaldehyde (w/w/w). Then, a total of 48 weaning piglets were randomly allotted to six dietary treatments: (1) basal diet; (2) 75 mg/kg chlortetracycline; (3) 100 mg/kg common EOs; (4) 500 mg/kg common EOs; (5) 100 mg/kg MEEOs; and (6) 500 mg/kg MEEO. The trial lasted 28 days. The results showed that piglets in the 100 mg/kg MEEOs group had the lowest diarrhea index during days 15–28 (P < 0.05). In addition, 100 mg/kg MEEOs significantly alleviated intestinal oxidative stress and inflammation (P < 0.05), whereas 500 mg/kg common EOs caused intestinal oxidative stress (P < 0.05) and may lead to intestinal damage through activation of inflammatory cytokine response. MEEOs (100 mg/kg) significantly reduced the ratio of the relative abundance of potential pathogenic and beneficial bacteria in the cecum and colon (P < 0.05), thus contributing to the maintenance of intestinal health. On the other hand, chlortetracycline caused an increase in the ratio of the relative abundance of potential pathogenic and beneficial bacteria in the colon (P < 0.05), which could potentially have adverse effects on the intestine. The addition of a high dose of MEEOs may have adverse effects on the intestine and may lead to diarrhea by increasing the level of colonic acetic acid (P < 0.05). Collectively, the results suggest that microencapsulation technology significantly promotes the positive effect of EOs on the intestinal health of weaning piglets and reduces the adverse effect of EOs, and 100 mg/kg MEEOs are recommended as a health promoter in piglets during the weaning period.

Regulatory Effects of Combined Dietary Supplementation With Essential Oils and Organic Acids on Microbial Communities of Cobb Broilers

The emergence and spread of antibiotic resistance genes in pathogenic microorganisms have resulted in many countries restricting the use of antibiotics as growth promoters in animal feed. The combined use of essential oils and organic acids can help maintain intestinal health, improve animal growth performance, and alleviate the negative effects of banned antibiotics for certain economically important animals. Although the modes of action for the combined dietary supplementation of essential oils and organic acids such as thymol-citric acid (EOA1) and thymol-butyric acid (EOA2) remain unclear, it is speculated that their activities are achieved through beneficial modulation of gastrointestinal microbial communities and inhibition of pathogen growth. In this study, 16S rDNA amplicon sequencing was used to analyze the effects of treatment with EOA1 and EOA2 on the jejunal, cecal, and fecal microbial communities of Cobb broilers while also evaluating effects over different broiler ages. The intestinal microbial communities of broilers developed with increasing age, and Lactobacillus gradually came to dominate the intestinal communities of treated broilers. Further, the microbial communities of feces were more complex than those of the jejuna and ceca. We systematically elucidate that the longitudinal changes in the intestinal microbial communities of Cobb broiler chickens at different ages. Meanwhile, we found that the addition of EOA1 or EOA2 to the diet: (1) inhibited the proliferation of Ralstonia pickettii and Alcaligenaceae in the jejuna on day 28, (2) promoted the colonization and growth of beneficial bacteria such as Lactobacillus, Clostridia, and Bacteroidia at various growth stages, and (3) enriched the abundance of certain microbiota functions, including biological pathways related to metabolism (e.g., enzyme families). Taken together, the results of this study demonstrate that EOA1 and EOA2 dietary supplementation can affect various microbial metabolic pathways related to the metabolism and absorption of nutrients via regulation of the intestinal microbial community structures of Cobb broilers.

Prevalence, serovar distribution, and antibiotic resistance of Salmonella spp. isolated from pork in China: A systematic review and meta-analysis

The epidemiological characteristics of Salmonella spp. in pork have been widely studied in China, but the results remain inconsistent. This study aimed to summarize the epidemiological characteristics of Salmonella spp. isolated from pork, including its prevalence, serovar distribution, and antibiotic resistance rate. We systematically reviewed published studies on Salmonella spp. isolated from pork in China between 2000 and 2020 in two Chinese and three English databases and quantitatively summarized its prevalence, serovar distribution, and antibiotic resistance using meta-analysis methods. Furthermore, we conducted subgroup analysis and meta-regression to explore the source of the heterogeneity from historical changes and regional difference perspectives. Ninety-one eligible studies published between 2000 and 2020 were included. The meta-analysis showed that the pooled prevalence of Salmonella isolated from pork was 0.17 (95% CI: 0.14, 0.20), with a detected growing trend over time. For the proportions of serovars, Derby (0.32, 95% CI: 0.26, 0.38), Typhimurium (0.10, 95% CI: 0.07, 0.15) and London (0.05, 95% CI: 0.03, 0.08) were dominant in these studies. The antibiotic resistance rates were high for tetracycline (0.68, 95% CI: 0.59, 0.77), sulfisoxazole (0.65, 95% CI: 0.45, 0.83), ampicillin (0.43, 95% CI: 0.34, 0.53), streptomycin (0.42, 95% CI: 0.29, 0.56), and sulfamethoxazole (0.42, 95% CI: 0.25, 0.60). The results of this study revealed a high prevalence, the regional characteristics of serovar distribution, and the severe challenges of antibiotic resistance of Salmonella originating from pork in China, suggesting the potential increasing risk and disease burden. Therefore, it is necessary to improve the prevention and control strategies of Salmonella in pork.

Hazard assessment of beta-lactams: Integrating in silico and QSTR approaches with in vivo zebrafish embryo toxicity testing

Antibiotics have emerged as a well-known representative of pharmaceuticals and personal care products (PPCPs) by causing public health and environmental problems due to their potential toxicity. β-lactams are the most commonly used antibiotics in the world. This study used zebrafish embryos to evaluate the toxicity of β-lactams. The results showed that 23 β-lactam compounds induced malformation and death in a concentration-response manner. Moreover, this study established and validated quantitative structure-toxicity relationship (QSTR) models for the toxicity of β-lactams in zebrafish. These models performed well and fast in the prediction of the acute toxicity of β-lactams. Structural interpretation indicated that the β-lactam ring, the thiazolidine/dihydrothiazine rings, the side chains, and spatial configuration are the main factors responsible for the toxicity of β-lactams. The results from our previous studies and this study also revealed that the potential biological risks caused by β-lactams and their degradation products could not be ignored. This study provided important data for further environmental risk assessment of β-lactams and regulatory purposes.

Pasteurella multocida capsular: lipopolysaccharide types D:L6 and A:L3 remain to be the main epidemic genotypes of pigs in China

Pasteurella multocida is a leading cause of respiratory disorders in pigs. This study was designed to understand the genotypical and antimicrobial resistant characteristics of P. multocida from pigs in China. To achieve this, we briefly investigated 158 P. multocida isolates from pigs with respiratory disorders in China between 2019 and 2020. Genotyping through multiplex PCR assays assigned these 158 isolates into capsular genotypes A (60.13%, 95/158), D (35.44%, 56/158), F (4.43%, 7/158), and/or lipopolysaccharide (LPS) genotypes L3 (28.48%, 45/158) and L6 (66.46%, 105/158). In addition, eight isolates (5.06%, 8/158) were found to be nontypable using the LPS genotyping method. When combining the capsular genotypes and the LPS genotypes, D: L6 (34.81%, 55/158) and A: L6 (31.65%, 50/158) were the predominant genotypes, followed by A: L3 (24.05%, 38/158). PCR detection of virulence factor-encoding genes showed that over 80% of the isolates were positive for exbB, tonB, exbD, ompH, ptfA, fimA, sodA, sodC, fur, ompA, oma87, plpB, hsf-2, nanH and hgbB, suggesting the presence of these genes were broad characteristics of P. multocida. We also found approximately 63.92% (101/158), 51.27% (81/158), 8.86% (14/158), 7.59% (12/158), 3.16% (5/158), 0.63% (1/158), and 0.63% (1/158) of the isolates grew well in media with the presence of colistin (4 μg/mL), tetracycline (16 μg/mL), tigecycline (1 μg/mL), ampicillin (32 μg/mL), chloramphenicol (32 μg/mL), cefepime (16 μg/mL), and ciprofloxacin (1 μg/mL), respectively. This study contributes to the understanding of genotypes and antimicrobial resistance profile of P. multocida currently circulation in pigs of China.

Antimicrobial Use and Susceptibility of Indicator Escherichia coli in Finnish Integrated Pork Production

In pigs, antimicrobial use (AMU) practices vary at different production phases between herds and between countries. Antimicrobial resistance (AMR) development is linked to AMU but recognized as a multi-factorial issue, and thus, any information increasing knowledge of AMU and AMR relationships is valuable. We described AMU and screened the carriage of different AMR phenotypes of indicator Escherichia coli in 25 selected Finnish piglet-producing and finishing herds that formed nine birth-to-slaughter production lines. Moreover, we studied associations between AMU and AMR in both herd types and throughout the production line. Treatment records were obtained from the national Sikava register for 1year, and AMU was quantified as mg/PCU (population correction unit) and TIs (treatment incidences). For phenotypic antimicrobial susceptibility testing, ten pen-level pooled feces samples (n=250) in each herd were collected from one room representing the oldest weaned piglets or the oldest finishing pigs. Majority of the medications (96.8%) was administered parenterally, and penicillin was the predominant antimicrobial in every herd. More different antimicrobial substances were used in piglet-producing than in finishing herds (median 5 and 1, respectively, p<0.001). As mg/PCU, sows had the highest AMU and suckling piglets had the highest TIs, whereas finishing pigs were the least treated age group. The proportion of susceptible indicator E. coli isolates of all studied isolates was 59.6%. Resistance was found most commonly against tetracycline, sulfamethoxazole, trimethoprim, and ampicillin, and multi-resistant (MR) isolates (46.5% of all resistant isolates) were resistant to a maximum of four different antimicrobials. Quinolone resistance was rare, and no resistance against 3rd-generation cephalosporins, meropenem, azithromycin, colistin, gentamicin, or tigecycline was detected. The main associations between AMU and AMR were found at antimicrobial group level when use was compared with the presence of AMR phenotypes. The proportion of resistant isolates was not associated with AMU, and herd size was not associated with either AMU or AMR. We suggest that the use of narrow-spectrum beta-lactams as a primary treatment option and lack of wide application of oral group medications potentially favors a good resistance pattern in integrated pork production.

Probiotic Paenibacillus polymyxa 10 and Lactobacillus plantarum 16 enhance growth performance of broilers by improving the intestinal health

With the ever-growing strict prohibitions on antibiotic growth promoters (AGP) in animal production, in-feed probiotics are becoming attractive alternatives to antibiotics in the poultry industry. To investigate the effects of Paenibacillus polymyxa 10 and Lactobacillus plantarum 16 on the growth performance and intestinal health of broilers, 540 male Cobb 500 broilers of 1 d old were randomly divided into 3 groups with 6 replicates per group and 30 chicks per replicate. Broilers were fed with either a basal diet or basal diets supplemented with 1 × 108 colony-forming units (CFU)/kg P. polymyxa 10 (BSC10) or L. plantarum 16 (Lac16) for 42 d. Results showed that Lac16 treatment improved (P < 0.05) the growth performance (body weight and feed conversion) of broilers at the starter phase, while BSC10 treatment slightly improved (P > 0.05) the growth performance of the starter phase broilers. The increased villus height (P < 0.05) at d 14, 21 and 42 and villus height to crypt depth ratio (P < 0.05) at d 14 and 21 were observed in the ileum of the 2 probiotic groups. Besides, transmission electron microscopy results showed that the 2 probiotics enhanced the intestinal epithelial barrier. Both probiotic treatments up-regulated (P < 0.05) the mRNA expression of fatty acid binding protein 1 (FABP1) and sodium-dependent glucose transporters-1 (SGLT-1) in the ileal mucosa of broilers at d 21. In addition, BSC10 and Lac16 treatments significantly (P < 0.05) increased the relative abundance of short-chain fatty acids-producing bacteria, such as Butyricicoccus pullicaecorum, Faecalibacterium prausnitzii, Lachnospira and Coprococcu, and significantly (P < 0.05) decreased the relative abundance of enteric pathogens (Escherichia coli, Bacteroides fragilis and Shigella sonnei). Furthermore, the 2 probiotic treatments also increased the positive connection among the intestinal microbes and the carbohydrate metabolism-related pathways of the intestinal bacteria (P < 0.05), with decreasing (P < 0.05) nucleotides biosynthesis-related pathways of the intestinal bacteria. Overall, these results suggest that the 2 probiotics, especially Lac16, have a potential beneficial effect on the growth performance and intestinal health of starter phase broilers.

Isolation and Characterization of Shiga Toxin-Producing Escherichia coli from Retail Beef Samples from Eight Provinces in China

While Shiga toxin-producing Escherichia coli (STEC) is a major foodborne pathogen worldwide, data on the molecular and phylogenetic properties of STEC isolates from retail beef samples in China remain scant. Fresh retail beef samples (n = 1062) were collected from eight provinces, and STEC isolates were recovered and characterized. PCR data showed that more than 50% of the samples were stx positive, and 82 STEC isolates were recovered from 14.8% (79/535) stx-positive enriched broths. In contrast, all ciprofloxacin resistant isolates (n = 19) and 13 cefotaxime (CTX) resistant isolates were eae positive and belonged to three serotypes: O111:H8, O26:H11, or O157:H7. Point mutations in quinolone resistance-determining regions and plasmid-mediated quinolone resistance determinants were identified in 16 and 20 isolates, respectively. Bla_CTX-M and a point mutation (C-42T) in ampC promoter were detected in 15 and 8 of the CTX resistant isolates, respectively. In addition, macrolide resistance gene mphA was identified in eight azithromycin resistant O111:H8 isolates and one O26:H11 isolate. Single nucleotide polymorphism analysis demonstrated that the O26 and O157 isolates had multiple origins, but the O111 isolates were closely related. Taken together, our data demonstrated that several sequence types associated with hemolytic uremic syndrome from the retail beef samples in China had developed into dangerous multidrug resistant pathogens. The resistant phenotype can facilitate their transmission among the farm animals and human beings when there is an antimicrobial selective pressure.

Whole-Genome Sequencing and Machine Learning Analysis of Staphylococcus aureus from Multiple Heterogeneous Sources in China Reveals Common Genetic Traits of Antimicrobial Resistance

Staphylococcus aureus is a worldwide leading cause of numerous diseases ranging from food-poisoning to lethal infections. Methicillin-resistant S. aureus (MRSA) has been found capable of acquiring resistance to most antimicrobials. MRSA is ubiquitous and diverse even in terms of antimicrobial resistance (AMR) profiles, posing a challenge for treatment. Here, we present a comprehensive study of S. aureus in China, addressing epidemiology, phylogenetic reconstruction, genomic characterization, and identification of AMR profiles. The study analyzes 673 S. aureus isolates from food as well as from hospitalized and healthy individuals. The isolates have been collected over a 9-year period, between 2010 and 2018, from 27 provinces across China. By whole-genome sequencing, Bayesian divergence analysis, and supervised machine learning, we reconstructed the phylogeny of the isolates and compared them to references from other countries. We identified 72 sequence types (STs), of which, 29 were novel. We found 81 MRSA lineages by multilocus sequence type (MLST), spa, staphylococcal cassette chromosome mec element (SCCmec), and Panton-Valentine leukocidin (PVL) typing. In addition, novel variants of SCCmec type IV hosting extra metal and antimicrobial resistance genes, as well as a new SCCmec type, were found. New Bayesian dating of the split times of major clades showed that ST9, ST59, and ST239 in China and European countries fell in different branches, whereas this pattern was not observed for the ST398 clone. On the contrary, the clonal transmission of ST398 was more intermixed in regard to geographic origin. Finally, we identified genetic determinants of resistance to 10 antimicrobials, discriminating drug-resistant bacteria from susceptible strains in the cohort. Our results reveal the emergence of Chinese MRSA lineages enriched of AMR determinants that share similar genetic traits of antimicrobial resistance across human and food, hinting at a complex scenario of evolving transmission routes. IMPORTANCE Little information is available on the epidemiology and characterization of Staphylococcus aureus in China. The role of food is a cause of major concern: staphylococcal foodborne diseases affect thousands every year, and the presence of resistant Staphylococcus strains on raw retail meat products is well documented. We studied a large heterogeneous data set of S. aureus isolates from many provinces of China, isolated from food as well as from individuals. Our large whole-genome collection represents a unique catalogue that can be easily meta-analyzed and integrated with further studies and adds to the library of S. aureus sequences in the public domain in a currently underrepresented geographical region. The new Bayesian dating of the split times of major drug-resistant enriched clones is relevant in showing that Chinese and European methicillin-resistant S. aureus (MRSA) have evolved differently. Our machine learning approach, across a large number of antibiotics, shows novel determinants underlying resistance and reveals frequent resistant traits in specific clonal complexes, highlighting the importance of particular clonal complexes in China. Our findings substantially expand what is known of the evolution and genetic determinants of resistance in food-associated S. aureus in China and add crucial information for whole-genome sequencing (WGS)-based surveillance of S. aureus.

Bacteriocinogenic probiotics as an integrated alternative to antibiotics in chicken production - why and how?

The misuse of antibiotics in the livestock industry has played an important role in the spread of resistant superbugs with severe health implications for humans. With the recent ban on the use of antibiotics in poultry and poultry feed in Canada and the USA, poultry farmers will have to rely on the use of alternatives to antibiotics (such as feed acidifiers, antibodies, bacteriophages, antimicrobial peptides, prebiotics, and probiotics) to maintain the same productivity and health of their livestock. Of particular interest are bacteriocinogenic probiotics, that is, bacterial strains capable of producing bacteriocins that confer health benefits on the host. These bacterial strains have multiple promising features, such as the ability to attach to the host mucosa, colonize, proliferate, and produce advantageous products such as bacteriocins and short-chain fatty acids. These not only affect pathogenic colonization but improve poultry phenotype as well. Bacteriocins are antimicrobial peptides with multiple promising features such as being non-harmful for human and animal consumption, non-disruptive to the host microbiota eubiosis, non-cytotoxic, and non-carcinogenic. Therefore, bacteriocinogenic probiotics are at the forefront to be excellent candidates for effective replacements to antibiotics. While evidence of their safety and effectiveness is accumulating in vitro and in vivo in inhibiting pathogens while promoting animal health, their safety and history of use in livestock remains unclear and requires additional investigations. In the present paper, we review the safety assessment regulations and commercialization policies on existing and novel bacteriocinogenic and bacteriocin products intended to be used in poultry feed as an alternative to antibiotics.

Status of antibiotic residues and detection techniques used in Chinese milk: A systematic review based on cross-sectional surveillance data

Antibiotic residues (ARs) in food of animal origin are of worldwide concern, particularly in China, the world's largest producer and consumer of antibiotics. Aiming to provide a reference for the use of antibiotics in dairy cows, for supervision and management departments in the detection of related antibiotics, and for guiding the safe use of antibiotics in food, this systematic review was carried out to determine the prevalence of ARs and antibiotic detection techniques in Chinese milk over the past three decades. The systematic review follows the PRSIMA (Preferred Reporting Items for Systematic Reviews and Meta-Analysis) guidelines. Both English (Cochrane, Embase, MEDLINE, PubMed, and Web of Science) and Chinese databases (Chinese National Knowledge Infrastructure, China Science and Technology Journal Database, and WanFang Database) were systematically searched, from inception to 31 July 2020. Among the 3131 citations screened, 46 active surveillance cross-sectional studies published between 1988 and 2020 in 26 Chinese provinces were eligible, providing antibiotic levels for a total of 8788 milk samples. Although the AR rates in fresh and sterilized milk fluctuate, they have largely declined in recent years. Among the 18 evaluated antibiotics, sulfamethoxazole, chloramphenicol, and trimethoprim are primary antibiotics with high residual rates. The most frequently used technique to monitor antibiotic levels in milk is 2,3,5-Triphenyltetrazolium chloride (TTC) staining. This review confirmed the importance of food safety monitoring and surveillance systems in preventing antibiotic exceedances in food. Several lessons learned from antibiotic surveillance and supervision in China were revealed. The provision of education to rural farmers should be strengthened to enhance their knowledge on antibiotic use in animal agriculture. Moreover, a standard operational protocol for screening and targeting antibiotics in dairy products should be considered to increase the comparability between cross-sectional active surveillance studies of AR in milk.

Replacement of Metaphylactic Antimicrobial Therapy by Oral Administration of Ligilactobacillus salivarius MP100 in a Pig Farm

Antibiotic use in swine production contributes to the emergence and spread of resistant bacteria, which poses a threat on human health. Therefore, alternative approaches must be developed. The objective of this work was the characterization of the probiotic properties of a Ligilactobacillus salivarius strain isolated from sow's milk and its application as an inoculated fermented feed to pregnant sows and piglets. The study was carried in a farm in which metaphylactic use of antimicrobials (including zinc oxide) was eliminated at the time of starting the probiotic intervention, which lasted for 2 years. Feces from 8-week-old piglets were collected before and after the treatment and microbiological and biochemical analyses were performed. The procedure led to an increase in the concentrations of clostridia and lactobacilli-related bacteria. Parallel, an increase in the concentration of butyrate, propionate and acetate was observed and a notable reduction in the presence of antibiotic resistant lactobacilli became apparent. In conclusion, replacement of antimicrobials by a microbiota-friendly approach was feasible and led to positive microbiological and biochemical changes in the enteric environment.

Pollution characteristics of livestock faeces and the key driver of the spread of antibiotic resistance genes

The increasing prevalence of antibiotic resistance genes (ARGs) in livestock and poultry faeces has attracted considerable amounts of attention. However, in the actual breeding environment, the key driver of the spread of ARGs and which bacteria are involved remain unclear. This study investigated 19 antibiotics and 4 heavy metals in 147 animal faeces. The results showed that piglet faeces exhibited the highest levels of antibiotics and heavy metals. Twelve ARGs, 4 mobile genetic elements (MGEs) and bacterial communities of piglet faeces from 6 pig farms were further assessed to determine the key driver and relevant mechanism of the spread of ARGs. Sulphonamides (SAs) explained 36.5% of the variance (P < 0.05) of the bacterial community and were significantly related to 8 genes (P < 0.01), indicating that SAs dominated the spread of ARGs and should be tightly supervised. Structural equation modelling (SEM) indicated that SAs increased the abundance of ARGs via two pathways: horizontal transfer of ARGs (involving 10 genera) and vertical transfer of ARGs (involving 26 genera). These results improve our understanding of the potential hosts involved in the spread of ARGs, suggesting that monitoring of the above potential hosts is also important in animal feeding practice.

Effect of Lactobacillus Species Probiotics on Growth Performance of Dual-Purpose Chicken

Introduction

In-feed probiotics are becoming attractive alternatives to antibiotics in the poultry industry due to the ever-growing strict prohibitions on antibiotic growth promoters (AGP) in animal production.

Methods

The study was conducted to investigate the effects of Lactobacillus paracaseis sparacasei and Lactobacillus rhamnosus on the growth performance of 120 day-olds randomly selected Sasso dual-purpose chicken. They were divided into four groups with two replicates per group and 15 chicks per replicate. The treatments were T₁ (control), T₂ (supplement diet with 4g probiotic), T₃ (supplement diet with 2g probiotic), T₄ (supplement diet with 1g probiotic). The experimental feeding trials were conducted after two weeks adaptation period.

Results

The present findings revealed that the chickens supplemented with Lactobacillus species probiotics during the first week of age have shown higher body weight than control (p < 0.05). The feed intake of week one of T₂ and T₃ were significantly higher (p< 0.05) than the T₁ (control). However, there was no significant difference (p> 0.05) in feed intake in the 2^nd, 3^rd, 4^th, and 5^{t h} weeks of all treatment groups. The present result showed that there was a significant body weight gain (p< 0.05) in all probiotic fed groups than the control group. The highest body weight gain was observed in chickens found in the T4 treatment group. Whereas the body weight gains significantly higher and improved the feed conversion (p<0.05) in the T₂ and T₄ than the T₁ (control). However, the feed conversion ratio was significantly influenced by probiotic inclusion in T₃ as compared to the control group.

Conclusion

Overall, the results suggest that Lactobacillus paracaseis sparacasei and Lactobacillus rhamnosus have a positive effect on the growth performance of broilers.

Comparison of China's and the European Union's Approaches to Antimicrobial Stewardship in the Pork Industry

Antimicrobial resistance (AMR) is a recognized global public health concern. Although the link between antimicrobial usage in food animals and AMR in humans is established, the detailed interactions are unclear. Antimicrobial stewardship (AMS) in livestock was first implemented in Europe with Sweden as the pioneer in 1986. Despite this head start, AMR is still an ongoing challenge for Europe. The European Union (EU) is an established agriculture producer, the second largest pork producer globally, and one of the largest markets for organic food. China is the global leader in both production and consumption of pork. China's rise in prosperity has led to an increase in its pork demand. Chinese producers commonly use antimicrobials during production for disease treatment and prevention to meet this increased demand. China's rising prosperity together with recent publicized food safety scandals, disease outbreaks in domestic livestock products, and increased AMR awareness have resulted in an increased willingness to pay and demand for organic food by Chinese consumers. Responding to the growing concerns of AMR by consumers and the World Health Organization (WHO), the Chinese government introduced a national pilot program in 2016 to reduce unnecessary antimicrobial use. Compared with China, the EU is a different entity as it is a political union comprising diverse countries and although it may have more experience in AMS, both entities face similar issues with AMR and increasing demand for organic food. Increased interest in organic food has arisen due to concerns about AMR, food safety, outbreaks of bacterial food contamination, and animal welfare. This article aims to compare the different AMS strategies employed by each entity, China and the EU, and how the increased demand for organic produce globally also influences the effort to reduce antimicrobial use in these entities' pork industries.

In vitro Assessment of Antiviral Effect of Natural Compounds on Porcine Epidemic Diarrhea Coronavirus

Organic acid and essential oils (EOs), well-known antimicrobials, could also possess antiviral activity, a characteristic which has not been completely addressed up to now. In this study, the effect of two organic acids (formic acid and sodium salt of coconut fatty acid distillates) and two single EO compounds (thymol and cinnamaldehye) was evaluated against porcine epidemic diarrhea virus (PEDV). The concentration used for each compound was established by cytotoxicity assays in Vero cells. The antiviral activity was then evaluated at three multiplicities of infection (MOIs) through visual cytopathic effect (CPE) evaluation and an alamarBlue assay as well as real-time reverse-transcription PCR (RT-qPCR) and viral titration of cell supernatants. Formic acid at at a dose of 1,200 ppm was the only compound which showed antiviral activity, with a weak reduction of CPE caused by PEDV. Through the alamarBlue fluorescence assay, we showed a significant anti-CPE effect of formic acid which could not be observed by using an inverted optical microscope. RT-qPCR and infectivity analysis also showed that formic acid significantly reduced viral RNA and viral titers in a PEDV MOI-dependent manner. Our results suggest that the antiviral activity of formic acid could be associated to its inhibitory effect on viral replication. Further studies are required to explore the anti-PEDV activity of formic acid under field conditions alone or together with other antiviral agents.

Emerging macrolide resistance in Bordetella pertussis in mainland China: Findings and warning from the global pertussis initiative

Whooping cough, or pertussis, is a highly communicable infectious disease caused by the bacterium Bordetella pertussis. Vaccination once reduced the incidence of the disease, but a global resurgence of the infection happened during the past two decades, likely due to the waning immunity of vaccination. Macrolides such as erythromycin and azithromycin are the drugs of primary choice for treatment. In this personal view, we call for attention to macrolide-resistant B. pertussis (MRBP), which has emerged and prevailed in mainland China for years and are exclusively mediated by mutations in the 23S rRNA gene. Whether the prevalence of MRBP in China results from overuse of azithromycin in clinical medicine remains unknown. The incidence of MRBP is low in other countries, but this could be a technical illusion since China employs culture as the mainstream diagnostic method whereas nucleic-acid amplification test being widely used in other countries fail to test antimicrobial susceptibility. Given the increasingly frequent global travel that facilitates microbial transmission worldwide, there is a pressing need to perform international surveillance on MRBP to prevent the potential circulation of the organism. Finding alternative agents that possess good activity against B. pertussis is also urgently required.