A survey of chlortetracycline concentration in feed and its residue in chicken egg in commercial layer farms

Review of antibiotic use and resistance in food animal production in WHO South-East Asia Region

Antimicrobial resistance is an emerging global threat to public health. The resistant bacteria in food animals can be transferred to humans through the food chain. Limited information on antimicrobial usage and resistance in food animals is available in Southeast Asia due to inadequate monitoring or surveillance systems. A literature review was conducted on antimicrobial use and resistance in food animal production in Southeast Asia for the period 2011-2020, to assess the scope and extent of antibiotic use and resistance. The countries included in the study were Bangladesh, Bhutan, Democratic People's Republic of Korea, India, Indonesia, Maldives, Myanmar, Nepal, Sri Lanka, Thailand and Timor-Leste. The information was categorised by country, production type and findings regarding antibiotic use and resistance. A total of 108 publications were included in the review. Results showed widespread use of critically and highly important antibiotics in livestock, poultry and aquacultured fish and their products. To curb the growing threat of antibiotic resistance, Southeast Asian countries need to strengthen surveillance and regulatory controls of antimicrobial use in food animal production through "One Health" approach.

Social demographics determinants for resistome and microbiome variation of a multiethnic community in Southern Malaysia

The prevalence of antibiotic-resistant bacteria in Southeast Asia is a significant concern, yet there is limited research on the gut resistome and its correlation with lifestyle and environmental factors in the region. This study aimed to profile the gut resistome of 200 individuals in Malaysia using shotgun metagenomic sequencing and investigate its association with questionnaire data comprising demographic and lifestyle variables. A total of 1038 antibiotic resistance genes from 26 classes were detected with a mean carriage rate of 1.74 ± 1.18 gene copies per cell per person. Correlation analysis identified 14 environmental factors, including hygiene habits, health parameters, and intestinal colonization, that were significantly associated with the resistome (adjusted multivariate PERMANOVA, p < 0.05). Notably, individuals with positive yeast cultures exhibited a reduced copy number of 15 antibiotic resistance genes. Network analysis highlighted Escherichia coli as a major resistome network hub, with a positive correlation to 36 antibiotic-resistance genes. Our findings suggest that E. coli may play a pivotal role in shaping the resistome dynamics in Segamat, Malaysia, and its abundance is strongly associated with the community's health and lifestyle habits. Furthermore, the presence of yeast appears to be associated with the suppression of antibiotic-resistance genes.

Occurrence of veterinary drugs and resistance genes during anaerobic digestion of poultry and cattle manures

In the present paper, the mesophilic (35 °C) and thermophilic (55 °C) biomethanization of poultry and cattle manures were investigated using biochemical methane potential (BMP) tests. Specific methane production (SMP), 24 pharmaceutical compounds (PhACs), and five antibiotic resistance genes (ARGs) (bla_KPC, ermB, qnrS, sul1 and tetW) together with the microbial community were analyzed. Mesophilic BMP tests resulted in the highest SMP when poultry manure was used (285.5 mL CH₄/g VSS with poultry vs 239.6 mL CH₄/g VSS with cattle manure) while thermophilic temperatures led to the highest SMP with cattle manure (231.2 mL CH₄/g VSS with poultry vs 238.0 mL CH₄/g VSS with cattle manure). Higher removals of veterinary pharmaceuticals were detected at 55 °C with both manures indicating that thermophilic digestion is better suited for the removal of these compounds. Tylosin, tilmicosin, chlortetracycline, and sulfamethoxazole presented removals higher than 50%, being the first two completely removed under mesophilic and thermophilic conditions. When comparing the relative abundance of ARGs at the end of each treatment, the most significant removal was found for qnrS which was not detected after the anaerobic treatment. The remaining ARGs did not suffer significant changes. Finally, microbial composition analysis showed that temperature affected the final microbial population more than the microorganisms present in the substrate or inoculum.

The gut microbiome of healthy Vietnamese adults and children is a major reservoir for resistance genes against critical antimicrobials

Antimicrobials are a key group of therapeutic agents. Given the animal/human population density and high antimicrobial consumption rate in Southeast Asia, the region is a focal area for monitoring antimicrobial resistance (AMR). Hypothesizing that the gastrointestinal tract of healthy individuals in Vietnam is a major source of AMR genes that may be transferred to pathogens, we performed shotgun metagenomic sequencing on fecal samples from 42 healthy Vietnamese people (21 children and 21 adults). We compared their microbiome profiles by age group and determined the composition of AMR genes. An analysis of the taxonomic profiles in the gut microbiome showed a clear differentiation by age, with young children (age <2 years) exhibiting a unique structure in comparison to adults and older children. We identified a total of 132 unique AMR genes, with macrolide, lincosamide, and streptogramin class resistance genes (ermB and lnuC) and tetracycline resistance genes being almost ubiquitous across the study population. Notably, samples from younger children were significantly associated with a greater number of AMR genes than other age groups, including key signature genes associated with AMR pathogens (eg, bla_CTX-M, mphA). Our data suggest that the gut microbiome of those living in Vietnam, particularly young children, is a substantial reservoir of AMR genes, which can be transferred to circulating enteric pathogens. Our data support the generation of longitudinal cohort studies of those living in urban and rural areas of developing countries to understand the behavior of these AMR reservoirs and their role in generating multidrug-resistant and extensively drug-resistant pathogens.

Trace Analysis of Multiclass Antibiotics in Food Products by Liquid Chromatography-Tandem Mass Spectrometry: Method Development

It is commonly known that the widespread use of antibiotics has led to their existence in food products as residues and ingestion of these food products may create a selection pressure on bacteria inhabiting the human body. In this study, an optimized method for the analysis of antibiotic residues in different food groups, including cereals, meat, eggs, milk, vegetables, and fruits, was developed using solvent extraction, solid-phase extraction cleanup, and liquid chromatography-mass spectrometry (LC-MS/MS). The limits of detection (LODs) were achieved as 0.007-1.1, 0.008-0.46, 0.002-0.67, 0.007-0.63, 0.001-0.098, and 0.005-0.26 ng/g in ng/g in cereals, meat, eggs, milk, vegetables, and fruits, respectively. The overall average recoveries at three spiking levels of the 81 antibiotics (5, 25, and 50 ng/g dry weight) were 82 ± 26, 77 ± 26, 70 ± 34, 69 ± 31, 73 ± 29, and 62 ± 37% in cereals, meat, eggs, milk, vegetables, and fruits, respectively. The method was then applied to the analysis of the targets in the collected wheat flour, mutton, chicken egg, boxed milk, cabbage, and banana samples, with the total concentration of the antibiotics detected being 4.4, 2.3, 36, 5.5, 2.7, and 14 ng/g, respectively. This work suggests that the developed method provides a time- and cost-effective method to identify and quantify antibiotic residues in common food products.

Synthesis and evaluation of bisulfate/mesylate-conjugated chlortetracycline with high solubility and bioavailability

The aim of this work is to improve the solubility and bioavailability of chlortetracycline and the function of the immune response. Chlortetracycline bisulfate and chlortetracycline mesylate were successfully synthesized and characterized with several techniques, including spectroscopy, chromatography and mass spectrometry, which demonstrated that the C4-dimethylamino group of chlortetracycline can accept a proton from sulfuric acid and methanesulfonic acid to form the corresponding salts. In addition, chlortetracycline bisulfate and chlortetracycline mesylate were more soluble in water than chlortetracycline hydrochloride, but the antibacterial activity was not enhanced. The influences of chlortetracycline hydrochloride, chlortetracycline bisulfate and chlortetracycline mesylate on chlortetracycline and immunoglobulin concentrations in mouse serum were also investigated. These results suggested that the chlortetracycline bisulfate and chlortetracycline mesylate have good bioavailability and strong immune response and have potential applications in animal breeding and formulation technologies.

Phenotypic and genotypic drug resistance profile of Salmonella serovars isolated from poultry farm and processing units located in and around Mumbai city, India

BACKGROUND AND AIM

The extensive use of antimicrobials in poultry has led to an increase in bacterial multidrug resistance, and the emergence of multidrug-resistant nontyphoidal Salmonella is a global problem. This study was performed to detect antibiotic-resistant Salmonella serovars in poultry farming and processing environment.

MATERIALS AND METHODS

A total of 956 various samples, comprising 432 farm origin, 324 poultry processing stage wise and environmental, and 154 product processing stages and environmental samples, were collected from poultry farms and processing units located in and around Mumbai city. Of a total of 71 recovered isolates, 42 randomly selected Salmonella isolates were subjected for antibiotic susceptibility testing by disk diffusion method and serotyping. A total of 31 serotypically confirmed isolates were characterized for the presence of tetA, tetB, bla TEM, and CTX-M gene.

RESULTS

Higher resistance was recorded against Doxycycline (100%), followed by Oxytetracycline (97.62%), Neomycin (88.10%), Erythromycin (83.33%), Tetracycline (78.57%), and Ceftizoxime (35.71%). Resistance from 0.00 to 26.19 percent was found to antimicrobials, namely Norfloxacin (26.19%), Ampicillin (21.43%), Azithromycin (21.43%), Ciprofloxacin (19.05%), Colistin (4.76%), Streptomycin (16.67%), Cefotaxime (14.19%), Enrofloxacin (14.29%), Amoxyclav (14.29%), Gentamicin (7.14%), Chloramphenicol (4.76%), Amikacin (4.76%), and Ceftazidime (0.0%). Results demonstrate that the Salmonella Virchow dominated and all serotypes were found to carry Tetracycline resistance gene tetA, 5 isolates were found to be positive for blaTEM , whereas none of the isolates were carrying tetB and CTX-M gene.

CONCLUSION

This study revealed that there is a significant rise of Tetracycline resistance with the presence of tetA gene in Salmonella spp. which indicates selective pressure for adopting resistance against tetracycline group of antibiotics.

Antimicrobial Consumption in Medicated Feeds in Vietnamese Pig and Poultry Production

Antimicrobials are extensively used as growth promoters in animal feeds worldwide, but reliable estimates are lacking. We conducted an internet-based survey of commercial chicken and pig feed products officially approved for sale in Vietnam over the period March-June 2015. Information on the antimicrobial contents in feed products, alongside animal production data, was used to estimate in-feed antimicrobial consumption to produce one kilogram of live animal (chicken, pig), as well as to estimate country-wide antimicrobial consumption through animal feeds. A total of 1462 commercial feed formulations were examined. The survey-adjusted estimated antimicrobial contents were 25.7 and 62.3 mg/kg in chicken and pig feeds, respectively. Overall, it was estimated that 77.4 mg [95% CI 48.1-106.8] and 286.6 mg [95% CI 191.6-418.3] of in-feed antimicrobials were used to raise 1 kg of live chicken and pig, respectively. Bacitracin (15.5% feeds), chlortetracycline (11.4%), and enramycin (10.8%) were the most common antimicrobials present in chicken feed formulations, whereas bacitracin (24.8%), chlortetracycline (23.9%), and florfenicol (17.4%) were the most common in pig feed formulations. Overall, 57% of the total quantitative usage consisted of antimicrobials regarded by WHO of importance for human medicine, including amoxicillin, colistin, tetracyclines, neomycin, lincomycin, and bacitracin. These figures confirm a very high magnitude of in-feed consumption of antimicrobials, especially in pig production. Results from this study should encourage further monitoring of antimicrobials used in animal production, and foster discussion about existing policies on inclusion of antimicrobials in animal feed rations.

Natural environments, ancestral diets, and microbial ecology: is there a modern "paleo-deficit disorder"? Part II

Famed microbiologist René J. Dubos (1901–1982) was an early pioneer in the developmental origins of health and disease (DOHaD) construct. In the 1960s, he conducted groundbreaking research concerning the ways in which early-life experience with nutrition, microbiota, stress, and other environmental variables could influence later-life health outcomes. He recognized the co-evolutionary relationship between microbiota and the human host. Almost 2 decades before the hygiene hypothesis, he suggested that children in developed nations were becoming too sanitized (vs. our ancestral past) and that scientists should determine whether the childhood environment should be “dirtied up in a controlled manner.” He also argued that oft-celebrated growth chart increases via changes in the global food supply and dietary patterns should not be equated to quality of life and mental health. Here in the second part of our review, we reflect the words of Dubos off contemporary research findings in the areas of diet, the gut-brain-axis (microbiota and anxiety and depression) and microbial ecology. Finally, we argue, as Dubos did 40 years ago, that researchers should more closely examine the relevancy of silo-sequestered, reductionist findings in the larger picture of human quality of life. In the context of global climate change and the epidemiological transition, an allergy epidemic and psychosocial stress, our review suggests that discussions of natural environments, urbanization, biodiversity, microbiota, nutrition, and mental health, are often one in the same.