Industrial food animal production, antimicrobial resistance, and human health

Rapid screening for specific glycosylation and pathogen interactions on a 78 species avian egg white glycoprotein microarray

There is an urgent need for discovery of novel antimicrobials and carbohydrate-based anti-adhesive strategies are desirable as they may not promote resistance. Discovery of novel anti-adhesive molecules from natural product libraries will require the use of a high throughput screening platform. Avian egg white (EW) provides nutrition for the embryo and protects against infection, with glycosylation responsible for binding certain pathogens. In this study, a microarray platform of 78 species of avian EWs was developed and profiled for glycosylation using a lectin panel with a wide range of carbohydrate specificities. The dominating linkages of sialic acid in EWs were determined for the first time using the lectins MAA and SNA-I. EW glycosylation similarity among the different orders of birds did not strictly depend on phylogenetic relationship. The interactions of five strains of bacterial pathogens, including Escherichia coli, Staphylococcus aureus and Vibrio cholera, identified a number of EWs as potential anti-adhesives, with some as strain- or species-specific. Of the two bacterial toxins examined, shiga-like toxin 1 subunit B bound to ten EWs with similar glycosylation more intensely than pigeon EW. This study provides a unique platform for high throughput screening of natural products for specific glycosylation and pathogen interactions. This platform may provide a useful platform in the future for discovery of anti-adhesives targeted for strain and species specificity.

The Prevalence of Extended-Spectrum Beta-Lactamase-Producing Multidrug-Resistant Escherichia Coli in Poultry Chickens and Variation According to Farming Practices in Punjab, India

BACKGROUND

Agricultural use of antimicrobials in subtherapeutic concentrations is increasing in response to the rising demand for food animal products worldwide. In India, the use of antimicrobials in food animal production is unregulated. Research suggests that many clinically important antimicrobials are used indiscriminately. This is the largest study to date in India that surveys poultry production to test for antimicrobial resistance and the occurrence of extended-spectrum β-lactamases (ESBLs) modulated by farming and managerial practices.

OBJECTIVES

Our goal was to survey poultry production for resistance to eleven clinically relevant antimicrobials and phenotypic occurrence of ESBLs as modulated by farming and managerial practices.

METHODS

Eighteen poultry farms from Punjab were surveyed, and 1,556 Escherichia coli isolates from 530 birds were tested for susceptibility to 11 antimicrobials using the disk diffusion method and validated using VITEK 2 (bioMérieux, Marcy-L’Étoile, France). Samples from 510 of these birds were phenotypically tested for ESBL production using the combination disk method and confirmed using VITEK 2. Generalized linear mixed models were used to infer differences in resistance profiles associated with different farming practices and facility types.

RESULTS

Resistance profiles were significantly different between broiler and layer farms. Broiler farms were 2.2 [ampicillin (AMP), p=0.017] to 23 [nalidixic acid (NX), p<0.001] times more likely to harbor resistant E. coli strains than layer farms. Adjusting for farm type (broiler vs. layer), the odds of resistance (although not statistically significant) to all antimicrobials except nitrofurantoin (NIT) were higher in independent facilities (IUs) as compared to contracted facilities (CFs). Increased prevalence of multidrug resistance (MDR; 94% compared to 60% in layers), including prevalence of ESBL-producing strains (87% compared to 42% in layers), was observed in broiler farms.

CONCLUSIONS

Our findings suggest that unregulated use of clinically relevant antimicrobials in Indian broiler and layer farms may contribute to the emergence of resistance and support the need to curb the nontherapeutic use of medically important antimicrobials in food animal production. https://doi.org/10.1289/EHP292.

Size, Composition, and Source Profiles of Inhalable Bioaerosols from Colorado Dairies

Particulate matter emissions from agricultural livestock operations contain both chemical and biological constituents that represent a potential human health hazard. The size and composition of these dusts, however, have not been well described. We evaluated the full size distribution (from 0 to 100 μm in aerodynamic diameter) and chemical/biological composition of inhalable dusts inside several Colorado dairy parlors. Four aerodynamic size fractions (<3, 3-10, 10-30, and >30 μm) were collected and analyzed using a combination of physiochemical techniques to understand the structure of bacterial communities and chemical constituents. Airborne particulate mass followed a bimodal size distribution (one mode at 3 μm and a second above 30 μm), which also correlated with the relative concentrations of the following microbiological markers: bacterial endotoxin, 3-hydroxy fatty acids, and muramic acid. Sequencing of the 16S-rRNA components of this aerosol revealed a microbiome derived predominantly from animal sources. Bacterial genera included Staphlyococcus, Pseudomonas, and Streptococcus, all of which have proinflammatory and pathogenic capacity. Our results suggest that the size distribution of bioaerosols emitted by dairy operations extends well above 10 μm in diameter and contains a diverse mixture of potentially hazardous constituents and opportunistic pathogens. These findings should inform the development of more effective emissions control strategies.

Whole-Genome Sequencing of Drug-Resistant Salmonella enterica Isolates from Dairy Cattle and Humans in New York and Washington States Reveals Source and Geographic Associations

Multidrug-resistant (MDR) Salmonella enterica can be spread from cattle to humans through direct contact with animals shedding Salmonella as well as through the food chain, making MDR Salmonella a serious threat to human health. The objective of this study was to use whole-genome sequencing to compare antimicrobial-resistant (AMR) Salmonella enterica serovars Typhimurium, Newport, and Dublin isolated from dairy cattle and humans in Washington State and New York State at the genotypic and phenotypic levels. A total of 90 isolates were selected for the study (37 S Typhimurium, 32 S Newport, and 21 S Dublin isolates). All isolates were tested for phenotypic antibiotic resistance to 12 drugs using Kirby-Bauer disk diffusion. AMR genes were detected in the assembled genome of each isolate using nucleotide BLAST and ARG-ANNOT. Genotypic prediction of phenotypic resistance resulted in a mean sensitivity of 97.2 and specificity of 85.2. Sulfamethoxazole-trimethoprim resistance was observed only in human isolates (P < 0.05), while resistance to quinolones and fluoroquinolones was observed only in 6 S Typhimurium isolates from humans in Washington State. S Newport isolates showed a high degree of AMR profile similarity, regardless of source. S Dublin isolates from New York State differed from those from Washington State based on the presence/absence of plasmid replicons, as well as phenotypic AMR susceptibility/nonsusceptibility (P < 0.05). The results of this study suggest that distinct factors may contribute to the emergence and dispersal of AMR S. enterica in humans and farm animals in different regions.IMPORTANCE The use of antibiotics in food-producing animals has been hypothesized to select for AMR Salmonella enterica and associated AMR determinants, which can be transferred to humans through different routes. Previous studies have sought to assess the degree to which AMR livestock- and human-associated Salmonella strains overlap, as well as the spatial distribution of Salmonella's associated AMR determinants, but have often been limited by the degree of resolution at which isolates can be compared. Here, a comparative genomics study of livestock- and human-associated Salmonella strains from different regions of the United States shows that while many AMR genes and phenotypes were confined to human isolates, overlaps between the resistomes of bovine and human-associated Salmonella isolates were observed on numerous occasions, particularly for S Newport. We have also shown that whole-genome sequencing can be used to reliably predict phenotypic resistance across Salmonella isolated from bovine sources.

The Prevalence of Antibiotic-Resistant Staphylococcus aureus Nasal Carriage among Industrial Hog Operation Workers, Community Residents, and Children Living in Their Households: North Carolina, USA

BACKGROUND

Antibiotic use in industrial hog operations (IHOs) can support the emergence of antibiotic-resistant (ABR) Staphylococcus aureus. The extent of ABR S. aureus exposure in IHO workers and children living in their households remains unclear.

OBJECTIVE

We investigated ABR S. aureus nasal carriage prevalence among adults with versus without occupational exposure to IHOs and among children living in their households.

METHODS

In total, 198 IHO worker-child household pairs and 202 community referent (CR) adult-child household pairs completed a questionnaire and provided a nasal swab which was analyzed for S. aureus, methicillin-resistant S. aureus (MRSA), multidrug-resistant S. aureus (MDRSA), absence of scn (putative marker of livestock association), and spa type.

RESULTS

S. aureus nasal carriage prevalence was higher among IHO (53%) compared with CR (31%) adults [adjusted prevalence ratio (aPR): 1.40; 95% confidence interval (CI): 1.07, 1.83], but MRSA nasal carriage prevalence was uncommon (2-3%) in IHO and CR adults. MDRSA nasal carriage prevalence was similar among IHO workers and CR adults (12% vs. 8%; aPR: 1.14; 95% CI: 0.56, 2.29). Nasal carriage prevalence was higher among IHO compared with CR children for S. aureus (49% vs. 31%; aPR: 1.50; 95% CI: 1.13, 1.99), MRSA (14% vs. 6%; aPR: 2.37; 95% CI: 1.14, 4.92), and MDRSA (23% vs. 8%; aPR: 2.64; 95% CI: 1.47, 4.75). We also found suggestive evidence of a higher prevalence of S. aureus, MRSA, and MDRSA among children living with an IHO worker who did versus did not report taking personal protective equipment (PPE) home from the IHO. Livestock-associated S. aureus nasal carriage predominated among IHO workers.

CONCLUSION

Our findings support the importance of further research on the prevalence and potential sources of exposure to ABR S. aureus among children living with IHO workers.

Current and future prospects for nanotechnology in animal production

Nanoparticles have been used as diagnostic and therapeutic agents in the human medical field for quite some time, though their application in veterinary medicine and animal production is still relatively new. Recently, production demands on the livestock industry have been centered around the use of antibiotics as growth promoters due to growing concern over microbial antibiotic resistance. With many countries reporting increased incidences of antibiotic-resistant bacteria, laws and regulations are being updated to end in-feed antibiotic use in the animal production industry. This sets the need for suitable alternatives to be established for inclusion in feed. Many reports have shown evidence that nanoparticles may be good candidates for animal growth promotion and antimicrobials. The current status and advancements of nanotechnological applications in animal production will be the focus of this review and the emerging roles of nanoparticles for nutrient delivery, biocidal agents, and tools in veterinary medicine and reproduction will be discussed. Additionally, influences on meat, egg, and milk quality will be reviewed.

The Food Production Environment and the Development of Antimicrobial Resistance in Human Pathogens of Animal Origin

Food-borne pathogens are a serious human health concern worldwide, and the emergence of antibiotic-resistant food pathogens has further confounded this problem. Once-highly-efficacious antibiotics are gradually becoming ineffective against many important pathogens, resulting in severe treatment crises. Among several reasons for the development and spread of antimicrobial resistance, their overuse in animal food production systems for purposes other than treatment of infections is prominent. Many pathogens of animals are zoonotic, and therefore any development of resistance in pathogens associated with food animals can spread to humans through the food chain. Human infections by antibiotic-resistant pathogens such as Campylobacter spp., Salmonella spp., Escherichia coli and Staphylococcus aureus are increasing. Considering the human health risk due to emerging antibiotic resistance in food animal-associated bacteria, many countries have banned the use of antibiotic growth promoters and the application in animals of antibiotics critically important in human medicine. Concerted global efforts are necessary to minimize the use of antimicrobials in food animals in order to control the development of antibiotic resistance in these systems and their spread to humans via food and water.

Antimicrobial Use and Veterinary Care among Agro-Pastoralists in Northern Tanzania

Frequent and unregulated use of antimicrobials (AM) in livestock requires public health attention as a likely selection pressure for resistant bacteria. Studies among small-holders, who own a large percentage of the world's livestock, are vital for understanding how practices involving AM use might influence resistance. We present a cultural-ecological mixed-methods analysis to explore sectors of veterinary care, loosely regulated AM use, and human exposure to AMs through meat and milk consumption across three rural to peri-urban Tanzanian ethnic groups (N = 415 households). Reported use of self-administered AMs varied by ethnic group (Maasai: 74%, Arusha: 21%, Chagga: 1%) as did consultation with professional veterinarians (Maasai: 36%, Arusha: 45%, Chagga: 96%) and observation of withdrawal of meat and milk from consumption during and following AM treatment (Maasai: 7%, Arusha: 72%, Chagga: 96%). The antibiotic oxytetracycline was by far the most common AM in this sample. Within ethnic groups, herd composition differences, particularly size of small-stock and cattle herds, were most strongly associated with differences in lay AM use. Among the Arusha, proxies for urbanization, including owning transportation and reliance on "zero-grazing" herds had the strongest positive associations with veterinarian consultation, while distance to urban centers was negatively associated. For Maasai, consultation was negatively associated with use of traditional healers or veterinary drug-shops. Observation of withdrawal was most strongly associated with owning technology among Maasai while Arusha observance displayed seasonal differences. This "One-Health" analysis suggests that livelihood and cultural niche factors, through their association with practices in smallholder populations, provide insight into the selection pressures that may contribute to the evolution and dissemination of antimicrobial resistance.

Antibiotic discovery throughout the Small World Initiative: A molecular strategy to identify biosynthetic gene clusters involved in antagonistic activity

The emergence of bacterial pathogens resistant to all known antibiotics is a global health crisis. Adding to this problem is that major pharmaceutical companies have shifted away from antibiotic discovery due to low profitability. As a result, the pipeline of new antibiotics is essentially dry and many bacteria now resist the effects of most commonly used drugs. To address this global health concern, citizen science through the Small World Initiative (SWI) was formed in 2012. As part of SWI, students isolate bacteria from their local environments, characterize the strains, and assay for antibiotic production. During the 2015 fall semester at Bowling Green State University, students isolated 77 soil‐derived bacteria and genetically characterized strains using the 16S rRNA gene, identified strains exhibiting antagonistic activity, and performed an expanded SWI workflow using transposon mutagenesis to identify a biosynthetic gene cluster involved in toxigenic compound production. We identified one mutant with loss of antagonistic activity and through subsequent whole‐genome sequencing and linker‐mediated PCR identified a 24.9 kb biosynthetic gene locus likely involved in inhibitory activity in that mutant. Further assessment against human pathogens demonstrated the inhibition of Bacillus cereus, Listeria monocytogenes, and methicillin‐resistant Staphylococcus aureus in the presence of this compound, thus supporting our molecular strategy as an effective research pipeline for SWI antibiotic discovery and genetic characterization.

Identification of antibiotic-resistant Escherichia coli isolated from a municipal wastewater treatment plant

The emergence and diffusion of antibiotic-resistant bacteria has been a major public health problem for many years now. In this study, antibiotic-resistance of coliforms and Escherichia coli were investigated after their isolation from samples collected in a municipal wastewater treatment plant in the Milan area (Italy) along different points of the treatment sequence: inflow to biological treatment; outflow from biological treatment following rapid sand filtration; and outflow from peracetic acid disinfection. The presence of E. coli that showed resistance to ampicillin (AMP) and chloramphenicol (CAF), used as representative antibiotics for the efficacy against Gram-positive and Gram-negative bacteria, was evaluated. After determining E. coli survival using increasing AMP and CAF concentrations, specific single-resistant (AMP^R or CAF^R) and double-resistant (AMP^R/CAF^R) strains were identified among E. coli colonies, through amplification of the β-lactamase Tem-1 (bla) and acetyl-transferase catA1 (cat) gene sequences. While a limited number of CAF^R bacteria was observed, most AMP^R colonies showed the specific resistance genes to both antibiotics, which was mainly due to the presence of the bla gene sequence. The peracetic acid, used as disinfection agent, showed to be very effective in reducing bacteria at the negligible levels of less than 10 CFU/100 mL, compatible with those admitted for the irrigation use of treated waters.

Linking the Microbiota, Chronic Disease, and the Immune System

Chronic inflammatory diseases (CIDs) are the most important causes of mortality in the world today and are on the rise. We now know that immune-driven inflammation is critical in the etiology of these diseases, though the environmental triggers and cellular mechanisms that lead to their development are still mysterious. Many CIDs are associated with significant shifts in the microbiota toward inflammatory configurations, which can affect the host both by inducing local and systemic inflammation and by alterations in microbiota-derived metabolites. This review discusses recent findings suggesting that shifts in the microbiota may contribute to chronic disease via effects on the immune system.

Discharge of swine wastes risks water quality and food safety: Antibiotics and antibiotic resistance genes from swine sources to the receiving environments

Swine feedlots are widely considered as a potential hotspot for promoting the dissemination of antibiotic resistance genes (ARGs) in the environment. ARGs could enter the environment via discharge of animal wastes, thus resulting in contamination of soil, water, and food. We investigated the dissemination and diversification of 22 ARGs conferring resistance to sulfonamides, tetracyclines, chloramphenicols, and macrolides as well as the occurrence of 18 corresponding antibiotics from three swine feedlots to the receiving water, soil environments and vegetables. Most ARGs and antibiotics survived the on-farm waste treatment processes in the three swine farms. Elevated diversity of ARGs was observed in the receiving environments including river water and vegetable field soils when compared with respective controls. The variation of ARGs along the vertical soil profiles of vegetable fields indicated enrichment and migration of ARGs. Detection of various ARGs and antibiotic residues in vegetables fertilized by swine wastes could be of great concern to the general public. This research demonstrated the contribution of swine wastes to the occurrence and development of antibiotic resistance determinants in the receiving environments and potential risks to food safety and human health.

Anticoccidial effects of herbal extracts on Eimeria tenella infection in broiler chickens: in vitro and in vivo study

Safe alternative anticoccidial drug to chemical feed additives are herbal extracts, because they don't results to tissue residue and drug resistance. In order to evaluate the effects of herbal extracts to control avian coccidiosis, 180 one-day-old broiler chickens were randomly divided into nine equal groups, as follows: (1) Biarum bovei (2) Nectaroscordum tripedale( 3) Dorema aucheri (4) Cichorium intybus (5) Prangos ferulaceae (6) diclazuril (7) Artemisia absinthium (8) infected control (9) uninfected control (each contains two groups). Administration of herbal extracts and supplementation of diclazuril was began 2 days before challenge and lasted for the duration of the experiment. The chicks of all the groups except uninfected control group were inoculated orally with sporulated oocysts (3 × 10(3) oocysts of Eimeria tenella) on the day 22 of age. The criteria employed were: body weight, feed conversion ratio, blood in feces, survival rate, lesion scoring, number of oocyst output per gram feces and histopathological changes. For histopathological evaluation, on day 12 post inoculation three birds from each group were randomly selected and humanly sacrificed. N. tripedale and diclazuril revealed better results in terms of growth performance, lesion score, extent of bloody diarrhea and oocyst count as compared to other herbal extracts. The increase in the severity of lesions was observed in groups of D. aucheri, A. absinthium, B. bovei, P. ferulaceae, C. intybus, diclazuril and N. tripedale, respectively. In conclusion, the current study showed that herbal extracts were effective in control of coccidiosis caused by the E. tenella infection.

Exposure to pathogens among workers in a poultry slaughter and processing plant

BACKGROUND

Working conditions in poultry slaughter/processing plants may expose workers to zoonotic pathogens. We explored exposure to pathogens among poultry slaughter/processing plant workers including job duties as risk factors.

METHODS

We collected questionnaire data on job duties and nasal swabs from 110 workers at one plant in South Carolina. Swabs were tested for Staphylococcus aureus and gram-negative organisms. Isolates were screened for antimicrobial susceptibility.

RESULTS

There was no differences in prevalence of S. aureus carriage based on job duties. As compared with office or packing workers, the adjusted odds of GNO carriage was 6.29 times (95% CI: 1.43, 27.71) higher in slaughter or carcass processing workers and 5.94 times (95% CI: 0.94, 37.50) higher in cleaning or maintenance workers.

CONCLUSIONS

Poultry processing plant workers may have increased exposure to GNOs, depending on job duties. Am. J. Ind. Med. 59:453-464, 2016. © 2016 Wiley Periodicals, Inc.

A review of the influence of treatment strategies on antibiotic resistant bacteria and antibiotic resistance genes

Antibiotic resistant bacteria (ARB) and antibiotic resistance genes (ARG) in the aquatic environment have become an emerging contaminant issue, which has implications for human and ecological health. This review begins with an introduction to the occurrence of ARB and ARG in different environmental systems such as natural environments and drinking water resources. For example, ARG or ARB with resistance to ciprofloxacin, sulfamethoxazole, trimethoprim, quinolone, vancomycin, or tetracycline (e.g., tet(A), tet(B), tet(C), tet(G), tet(O), tet(M), tet(W), sul I, and sul II) have been detected in the environment. The development of resistance may be intrinsic, may be acquired through spontaneous mutations (de novo), or may occur due to horizontal gene transfer from donor bacteria, phages, or free DNA to recipient bacteria. An overview is also provided of the current knowledge regarding inactivation of ARB and ARG, and the mechanism of the effects of different disinfection processes in water and wastewater (chlorination, UV irradiation, Fenton reaction, ozonation, and photocatalytic oxidation). The effects of constructed wetlands and nanotechnology on ARB and ARG are also summarized.

Potential Sources and Transmission of Salmonella and Antimicrobial Resistance in Kampala, Uganda

In sub‒Saharan Africa, non‒typhoidal Salmonellae (NTS) cause invasive disease particularly in children and HIV infected adults, but the disease epidemiology is poorly understood. Between 2012 and 2013, we investigated NTS sources and transmission in Kampala. We detected Salmonella in 60% of the influent and 60% of the effluent samples from a wastewater treatment plant and 53.3% of the influent and 10% of the effluent samples from waste stabilization ponds that serve the human population; 40.9% of flush‒water samples from ruminant slaughterhouses, 6.6% of the poultry fecal samples from live bird markets and 4% of the fecal samples from swine at slaughter; and in 54.2% of the water samples from a channel that drains storm–water and effluents from the city. We obtained 775 Salmonella isolates, identified 32 serovars, and determined resistance to 15 antimicrobials. We genotyped common serovars using multiple‒locus variable number tandem repeats analysis or pulsed‒field gel electrophoresis. In addition, we analyzed 49 archived NTS isolates from asymptomatic livestock and human clinical cases. Salmonella from ruminant and swine sources were mostly pan‒susceptible (95%) while poultry isolates were generally more resistant. Salmonella Kentucky isolated from poultry exhibited extensive drug resistance characterized by resistance to 10 antimicrobials. Interestingly, similar genotypes of S. Kentucky but with less antimicrobial resistance (AMR) were found in poultry, human and environmental sources. The observed AMR patterns could be attributed to host or management factors associated with production. Alternatively, S. Kentucky may be prone to acquiring AMR. The factors driving AMR remain poorly understood and should be elucidated. Overall, shared genotypes and AMR phenotypes were found in NTS from human, livestock and environmental sources, suggesting zoonotic and environmental transmissions most likely occur. Information from this study could be used to control NTS transmission.

Biodiversity and health: Lessons and recommendations from an interdisciplinary conference to advise Southeast Asian research, society and policy

Southeast Asia is an economic, biodiverse, cultural and disease hotspot. Due to rapid socio-economic and environmental changes, the role of biodiversity and ecosystems for human health ought to be examined and communicated to decision-makers and the public. We therefore summarized the lessons and recommendations from an interdisciplinary conference convened in Cambodia in 2014 to advise Southeast Asian societies on current research efforts, future research needs, and to provide suggestions for improved education, training and science-policy interactions. First, we reviewed several examples of the important role of ecosystems as 'sentinels' in the sense that potentially harmful developments for human health become first apparent in ecosystem components. Other ecosystem services which also benefit human well-being are briefly summarized. Second, we summarized the recommendations of the conference's roundtable discussions and added recent developments in the science-policy interface. The recommendations were organized along five themes: Ethical and legal considerations; implementation of the One Health approach; education, training, and capacity building; future research priorities; and potential science-policy interactions. While the role of biodiversity for human health needs further research, especially for zoonoses and emerging diseases, many direct and indirect benefits to human health are already apparent, but have yet to filter down to the science-policy interface in order to influence legislation and enforcement. Therefore, efforts to strengthen the interface in Southeast Asia should become a high priority in order to strengthen the health and resilience of Southeast Asian societies.

Antibiotic Resistance in Animal and Environmental Samples Associated with Small-Scale Poultry Farming in Northwestern Ecuador

In developing countries, small-scale poultry farming employing antibiotics as growth promoters is being advanced as an inexpensive source of protein and income. Here, we present the results of a large ecoepidemiological study examining patterns of antibiotic resistance (AR) in E. coli isolates from small-scale poultry production environments versus domestic environments in rural Ecuador, where such backyard poultry operations have become established over the past decade. Our previous research in the region suggests that introduction of AR bacteria through travel and commerce may be an important source of AR in villages of this region. This report extends the prior analysis by examining small-scale production chicken farming as a potential source of resistant strains. Our results suggest that AR strains associated with poultry production likely originate from sources outside the study area and that these outside sources might be a better place to target control efforts than local management practices.

The effects of animal agriculture on the spread of antibiotic resistance (AR) are cross-cutting and thus require a multidisciplinary perspective. Here we use ecological, epidemiological, and ethnographic methods to examine populations of Escherichia coli circulating in the production poultry farming environment versus the domestic environment in rural Ecuador, where small-scale poultry production employing nontherapeutic antibiotics is increasingly common. We sampled 262 “production birds” (commercially raised broiler chickens and laying hens) and 455 “household birds” (raised for domestic use) and household and coop environmental samples from 17 villages between 2010 and 2013. We analyzed data on zones of inhibition from Kirby-Bauer tests, rather than established clinical breakpoints for AR, to distinguish between populations of organisms. We saw significantly higher levels of AR in bacteria from production versus household birds; resistance to either amoxicillin-clavulanate, cephalothin, cefotaxime, and gentamicin was found in 52.8% of production bird isolates and 16% of household ones. A strain jointly resistant to the 4 drugs was exclusive to a subset of isolates from production birds (7.6%) and coop surfaces (6.5%) and was associated with a particular purchase site. The prevalence of AR in production birds declined with bird age (P < 0.01 for all antibiotics tested except tetracycline, sulfisoxazole, and trimethoprim-sulfamethoxazole). Farming status did not impact AR in domestic environments at the household or village level. Our results suggest that AR associated with small-scale poultry farming is present in the immediate production environment and likely originates from sources outside the study area. These outside sources might be a better place to target control efforts than local management practices.

IMPORTANCE In developing countries, small-scale poultry farming employing antibiotics as growth promoters is being advanced as an inexpensive source of protein and income. Here, we present the results of a large ecoepidemiological study examining patterns of antibiotic resistance (AR) in E. coli isolates from small-scale poultry production environments versus domestic environments in rural Ecuador, where such backyard poultry operations have become established over the past decade. Our previous research in the region suggests that introduction of AR bacteria through travel and commerce may be an important source of AR in villages of this region. This report extends the prior analysis by examining small-scale production chicken farming as a potential source of resistant strains. Our results suggest that AR strains associated with poultry production likely originate from sources outside the study area and that these outside sources might be a better place to target control efforts than local management practices.

Multifunctional Polyphenols- and Catecholamines-Based Self-Defensive Films for Health Care Applications

In an era of relentless evolution of antimicrobial resistance, there is an increasing demand for the development of efficient antimicrobial coatings or surfaces for food, biomedical, and industrial applications. This study reports the laccase-catalyzed room-temperature synthesis of mechanically robust, thermally stable, broad spectrum antimicrobial films employing interfacial interactions between poly(vinyl alcohol), PVA, and 14 naturally occurring catecholamines and polyphenols. The oxidative products of catecholamines and polyphenols reinforce the PVA films and also alter their surface and bulk properties. Among the catecholamines-reinforced films, optimum surface and bulk properties can be achieved by the oxidative products of epinephrine. For polyphenols, structure-property correlation reveals an increase in surface roughness and elasticity of PVA films with increasing number of phenolic groups in the precursors. Interestingly, PVA films reinforced with oxidized/polymerized products of pyrogallol (PG) and epinephrine (EP) display potent antimicrobial activity against pathogenic Gram-positive and Gram-negative strains, whereas hydroquinone (HQ)-reinforced PVA films display excellent antimicrobial properties against Gram-positive bacteria only. We further demonstrate that HQ and PG films retain their antimicrobial efficacy after steam sterilization. With an increasing trend of giving value to natural and renewable resources, our results have the potential as durable self-defensive antimicrobial surfaces/films for advanced healthcare and industrial applications.

The Future of Antibiotics and Meat

This chapter discusses antibiotic use in the livestock industry and potential ramifications for human health. Antibiotics are routinely administered to food animals, primarily at sub-therapeutic levels. The extensive use of antibiotics in global animal husbandry in quantities greater than used for humans is creating antibiotic resistance. There is evidence that antibiotic resistant organisms emerging in food animals transfer to humans through the food chain, environmental contamination, direct association with animals or through mobile resistant genetic elements resulting in co-resistance to other antibiotics. No new classes of antibiotics have been developed since the 1980s. Intensifying use of existing antibiotics for meat production poses new challenges for treating humans, needs to be taken seriously and dealt with urgently. This chapter argues that reduced meat consumption is an under-considered but essential part in any suite of solutions aimed at preserving the use of antibiotics for human treatment.

Amphixenosic Aspects of Staphylococcus aureus Infection in Man and Animals

According to the mode of transmission, Staphylococcus aureus infection between hosts is classified as "direct zoonoses," or infection that is transmitted from an infected vertebrate host to a susceptible host (man) by direct contact, by contact with a fomite or by a mechanical vector. The agent itself undergoes little or no propagative or developmental changes during transmission. According to the reservoir host, staphylococcosis is most precisely defined as "zooanthroponoses" or infections transmitted from man to lower vertebrate animals (e.g., streptococci, diphtheria, Enterobacteriaceae, human tuberculosis in cattle and parrots), but also "anthropozoonoses" or infections transmitted to man from lower vertebrate animals. In particular, actually, the correct definition of S. aureus infections between humans and animals is "amphixenoses" or infections maintained in both man and lower vertebrate animals and transmitted in either direction. S. aureus exhibits tropisms to many distinct animal hosts. While spillover events can occur wherever there is an interface between host species, changes in host tropism only occur with the establishment of sustained transmission in the new host species, leading to clonal expansion. Although the genomic variation underpinning adaptation in S. aureus genotypes infecting bovids and poultry has been well characterized, the frequency of switches from one host to another remains obscure. In this review, we sought to identify the sustained switches in host tropism in the S. aureus population, both anthroponotic and zoonotic, and their distribution over the species phylogeny. S. aureus is an organism with the capacity to switch into and adapt to novel hosts, even after long periods of isolation in a single host species. Based on this evidence, animal-adapted S. aureus lineages exhibiting resistance to antibiotics must be considered a major threat to public health, as they can adapt to the human population.

Vigilance for Salmonella in Feedstuffs Available in Costa Rica: Prevalence, Serotyping and Tetracycline Resistance of Isolates Obtained from 2009 to 2014

Relevant epidemiological information is provided in this report for Salmonella based on data obtained from a Costa Rican surveillance program for animal feeds. In addition to prevalence, a description in terms of serotypes and tetracycline (TET) resistance of the isolates is included. A total of 1725 feed and feed ingredients samples were analyzed during 2009 and 2014, from which 110 Salmonella strains were recovered (76 from poultry, 23 from meat and bone meal [MBM], 3 from pet foods, and 8 from other feed). Retrieved isolates were serotyped and tested for minimum inhibitory concentration (MIC) against TET. Salmonella strains were found mainly from poultry feed (different growth stages, n = 76/110; 69.1%) and MBM (n = 23/109; 21.1%). The rest of the isolates were recovered from feather meal, pet food, fish meal (n = 3/110; 2.3% each) and swine feed (n = 1/110; 0.9%). From the different serotypes recovered (n = 21), the most common were Salmonella Give (n = 18; 13.8%) and Salmonella Rissen (n = 6; 4.6%) for MBM and Salmonella Havana (n = 14; 10.8%), Salmonella Rissen, Salmonella Soerenga, and Salmonella Schwarzengrund (n = 8; 6.2% each) in poultry feed. Recovered strains were regarded to be sensitive or have an intermediate resistance to TET as evidenced by their MIC50 and MIC90 concentrations of 4 and 8 μg/mL for MBM and poultry feed, respectively. Compound feed and MBM samples exhibited strains characterized by 86.8 and 88.9% of the isolates classified (according to CLSI, 2015 ) as sensitive, 7.7 and 3.7% as intermediate, and 5.5% (with >256 μg/mL as the highest concentration) and 7.4% (with 64 μg/mL as the highest concentration) as resistant to TET, respectively. Salmonella serovars Anatum and Havana exhibited the highest resistance profile >256 and 128 μg/mL, respectively. Hence, MBM and poultry feed seem to be a target of interest if Salmonella incidence is to be controlled. Serotypes recovered have in the past demonstrated pathogenic capability; therefore, hereafter a stricter surveillance program may be in order.

Occupational Exposure to Swine, Poultry, and Cattle and Antibody Biomarkers of Campylobacter jejuni Exposure and Autoimmune Peripheral Neuropathy

INTRODUCTION

Foodborne Campylobacter jejuni infection has been associated with an increased risk of autoimmune peripheral neuropathy, but risks of occupational exposure to C. jejuni have received less attention. This study compared anti-C. jejuni IgA, IgG, and IgM antibody levels, as well as the likelihood of testing positive for any of five anti-ganglioside autoantibodies, between animal farmers and non-farmers. Anti-C. jejuni antibody levels were also compared between farmers with different animal herd or flock sizes. The relationship between anti-C. jejuni antibody levels and detection of anti-ganglioside autoantibodies was also assessed.

METHODS

Serum samples from 129 Agricultural Health Study swine farmers (some of whom also worked with other animals) and 46 non-farmers, all from Iowa, were analyzed for anti-C. jejuni antibodies and anti-ganglioside autoantibodies using ELISA. Information on animal exposures was assessed using questionnaire data. Anti-C. jejuni antibody levels were compared using Mann-Whitney tests and linear regression on log-transformed outcomes. Fisher's Exact Tests and logistic regression were used to compare likelihood of positivity for anti-ganglioside autoantibodies.

RESULTS

Farmers had significantly higher levels of anti-C. jejuni IgA (p < 0.0001) and IgG (p = 0.02) antibodies compared to non-farmers. There was no consistent pattern of anti-C. jejuni antibody levels based on animal herd or flock size. A higher percentage of farmers (21%) tested positive for anti-ganglioside autoantibodies compared to non-farmers (9%), but this difference was not statistically significant (p = 0.11). There was no significant association between anti-C. jejuni antibody levels and anti-ganglioside autoantibodies.

CONCLUSIONS

The findings provide evidence that farmers who work with animals may be at increased risk of exposure to C. jejuni. Future research should include longitudinal studies of exposures and outcomes, as well as studies of interventions to reduce exposure. Policies to reduce occupational exposure to C. jejuni should be considered.

Nontherapeutic Use of Antimicrobial Agents in Animal Agriculture: Implications for Pediatrics

Antimicrobial resistance is one of the most serious threats to public health globally and threatens our ability to treat infectious diseases. Antimicrobial-resistant infections are associated with increased morbidity, mortality, and health care costs. Infants and children are affected by transmission of susceptible and resistant food zoonotic pathogens through the food supply, direct contact with animals, and environmental pathways. The overuse and misuse of antimicrobial agents in veterinary and human medicine is, in large part, responsible for the emergence of antibiotic resistance. Approximately 80% of the overall tonnage of antimicrobial agents sold in the United States in 2012 was for animal use, and approximately 60% of those agents are considered important for human medicine. Most of the use involves the addition of low doses of antimicrobial agents to the feed of healthy animals over prolonged periods to promote growth and increase feed efficiency or at a range of doses to prevent disease. These nontherapeutic uses contribute to resistance and create new health dangers for humans. This report describes how antimicrobial agents are used in animal agriculture, reviews the mechanisms of how such use contributes to development of resistance, and discusses US and global initiatives to curb the use of antimicrobial agents in agriculture.

Genetic characterization of antibiotic-resistant Staphylococcus aureus from milk in the North-West Province, South Africa

Food borne diseases are a major public health concern worldwide. Staphylococcus aureus is one of the potential food borne pathogens which causes nosocomial and community acquired infections. In the present study, 74 representative strains of S. aureus isolated and characterized in previous study from different milk samples were subjected to random amplified polymorphic DNA (RAPD) polymerase chain reaction (PCR) and enterobacterial repetitive intergenic consensus (ERIC)-PCR to generate fingerprints to determine the genetic relationships of the isolated strains. A total of 20 RAPD patterns were generated and the number of amplified fragments obtained ranged from 0 to 8 with molecular weight ranging from 250 to 2000 bp. A dendrogram based on fingerprinting pattern grouped isolates into twelve major clusters (I–XII). In the case of ERIC-PCR 9 banding patterns were obtained with amplicons ranging from 1 to 8 and band sizes ranging from 250 to 2000 bp. A total of four major clusters (I–IV) were observed in the dendrogram based on ERIC fingerprints. The discrete banding patterns obtained both from ERIC-PCR and RAPD-PCR showed remarkably the genetic diversity of S. aureus. The findings of this study indicate that raw, bulk and pasteurized milk in the North-West Province was contaminated with toxigenic and multi-drug resistant S. aureus strains. This emphasizes the need to implement appropriate control measures to reduce contamination as well as the spread of virulent S. aureus strains to reduce the burden of disease in humans.

George DM, D’Adamo CR. Evaluation of the Balanced Menus Challenge: a healthy food and sustainability programme in hospitals in Maryland

OBJECTIVE

The Balanced Menus Challenge (BMC) is a national effort to bring the healthiest, most sustainably produced meat available into health-care settings to preserve antibiotic effectiveness and promote good nutrition. The present study evaluated the outcomes of the BMC in the Maryland/Washington, DC region.

DESIGN

The BMC is a cost-effective programme whereby participating hospitals reduce meat purchases by 20 % of their budget, then invest the savings into purchasing sustainably produced meat. A mixed-methods retrospective assessment was conducted to assess (i) utilization of the BMC 'implementation toolkit' and (ii) achievement of the 20 % reduction in meat purchases. Previous survey data were reviewed and semi-structured interviews were conducted.

SETTING

Hospitals located in the Maryland/Washington, DC region, USA, that adopted the BMC.

SUBJECTS

Twelve hospitals signed the BMC in the Maryland/Washington, DC region and six were available for interview.

RESULTS

Three hospitals in the Maryland/Washington, DC region that signed the BMC tracked their progress and two achieved a reduction in meat procurement by ≥20 %. One hospital demonstrated that the final outcome goal of switching to a local and sustainable source for meat is possible to achieve, at least for a portion of the meal budget. The three hospitals that reduced meat purchases also received and used the highest number of BMC implementation tools. There was a positive correlation between receipt and usage of implementation tools (r=0·93, P=0·005).

CONCLUSIONS

The study demonstrates that hospitals in the Maryland/Washington, DC region that sign the BMC can increase the amount of sustainably produced meat purchased and served.

Detection of Antibiotic Resistant Staphylococcus aureus from Milk: A Public Health Implication

The aim of this study was to investigate the occurrence, antibiotic susceptibility profiles, and virulence genes determinants of S. aureus isolated from milk obtained from retail outlets of the North-West Province, South Africa. To achieve this, 200 samples of raw, bulk and pasteurised milk were obtained randomly from supermarkets, shops and some farms in the North-West Province between May 2012 and April 2013. S. aureus was isolated and positively identified using morphological (Gram staining), biochemical (DNase, catalase, haemolysis and rapid slide agglutination) tests, protein profile analysis (MALDI-TOF mass spectrometry) and molecular (nuc specific PCR) methods. The antimicrobial resistance profiles of the isolates were determined using the phenotypic agar diffusion method. Genes encoding enterotoxins, exfoliative toxins and collagen adhesins were also screened using PCR. Among all the samples examined, 30 of 40 raw milk samples (75%), 25 of 85 bulk milk samples (29%) and 10 of 75 pasteurised milk samples (13%) were positive for S. aureus. One hundred and fifty-six PCR-confirmed S. aureus isolates were obtained from 75 contaminated milk samples. A large proportion (60%-100%) of the isolates was resistant to penicillin G, ampicillin, oxacillin, vancomycin, teicoplanin and erythromycin. On the contrary, low level resistance (8.3%-40%) was observed for gentamicin, kanamycin and sulphamethoxazole. Methicillin resistance was detected in 59% of the multidrug resistant isolates and this was a cause for concern. However, only a small proportion (20.6%) of these isolates possessed PBP2a which codes for Methicillin resistance in S. aureus. In addition, 32.7% of isolates possessed the sec gene whereas the sea, seb sed, see, cna, eta, etb genes were not detected. The findings of this study showed that raw, bulk and pasteurised milk in the North-West Province is contaminated with toxigenic and multi-drug resistant S. aureus strains. There is a need to implement appropriate control measures to reduce contamination as well as the spread of virulent S. aureus strains and the burden of disease in humans.

Antimicrobial use in swine production and its effect on the swine gut microbiota and antimicrobial resistance

Antimicrobials have been used in swine production at subtherapeutic levels since the early 1950s to increase feed efficiency and promote growth. In North America, a number of antimicrobials are available for use in swine. However, the continuous administration of subtherapeutic, low concentrations of antimicrobials to pigs also provides selective pressure for antimicrobial-resistant bacteria and resistance determinants. For this reason, subtherapeutic antimicrobial use in livestock remains a source of controversy and concern. The swine gut microbiota demonstrates a number of changes in response to antimicrobial administration depending on the dosage, duration of treatment, age of the pigs, and gut location that is sampled. Both culture-independent and -dependent studies have also shown that the swine gut microbiota contains a large number of antimicrobial resistance determinants even in the absence of antimicrobial exposure. Heavy metals, such as zinc and copper, which are often added at relatively high doses to swine feed, may also play a role in maintaining antimicrobial resistance and in the stability of the swine gut microbiota. This review focuses on the use of antimicrobials in swine production, with an emphasis on the North American regulatory context, and their effect on the swine gut microbiota and on antimicrobial resistance determinants in the gut microbiota.

Carbohydrate scaffolds as glycosyltransferase inhibitors with in vivo antibacterial activity

The rapid rise of multi-drug-resistant bacteria is a global healthcare crisis, and new antibiotics are urgently required, especially those with modes of action that have low-resistance potential. One promising lead is the liposaccharide antibiotic moenomycin that inhibits bacterial glycosyltransferases, which are essential for peptidoglycan polymerization, while displaying a low rate of resistance. Unfortunately, the lipophilicity of moenomycin leads to unfavourable pharmacokinetic properties that render it unsuitable for systemic administration. In this study, we show that using moenomycin and other glycosyltransferase inhibitors as templates, we were able to synthesize compound libraries based on novel pyranose scaffold chemistry, with moenomycin-like activity, but with improved drug-like properties. The novel compounds exhibit in vitro inhibition comparable to moenomycin, with low toxicity and good efficacy in several in vivo models of infection. This approach based on non-planar carbohydrate scaffolds provides a new opportunity to develop new antibiotics with low propensity for resistance induction.

Multiple antibiotic resistance indexing of Escherichia coli to identify high-risk sources of faecal contamination of water

We evaluated the antibiogram profile of Escherichia coli (n = 300) isolated from selected rivers in Osun State, Nigeria. The identities of the E. coli isolates were confirmed by polymerase chain reaction (PCR) technique. Susceptibility of the isolates to 20 antibiotics conventionally used in clinical cases was assessed in vitro by the standardized agar disc-diffusion method. All the isolates were susceptible to imipenem, meropenem, amikacin and gatilofloxacin. The isolates were variously susceptible to the other antibiotics as follows: ciprofloxacin (96 %), kanamycin (95 %), neomycin (92 %), streptomycin (84 %), chloramphenicol (73 %), nalidixic acid (66 %), nitrofurantoin (64 %), gentamycin (63 %), doxycycline (58 %), cefepime (57 %), tetracycline (49 %) and cephalothin (42 %). The multiple antibiotic resistance indexing ranged from 0.50 to 0.80 for all the sampling locations and exceeded the threshold value of 0.2, suggesting the origin of the isolates to be of high antimicrobial usage. Our findings signify an increase in the incidence of antimicrobial resistance of E. coli towards conventionally used antibiotics necessitating proper surveillance programmes towards the monitoring of antimicrobial resistance determinants in water bodies.

Periodontal pathogens and tetracycline resistance genes in subgingival biofilm of periodontally healthy and diseased Dominican adults

Objective

The objective of this study was to compare the periodontopathogen prevalence and tetracycline resistance genes in Dominican patients with different periodontal conditions.

Methods

Seventy-seven samples were collected from healthy, gingivitis, chronic (CP) and aggressive (AgP) periodontitis patients. Porphyromonas gingivalis, Treponema denticola, Tannerella forsythia, Aggregatibacter actinomycetemcomitans, Fusobacterium nucleatum, Prevotella intermedia, Parvimonas micra, Eikenella corrodens and Dialister pneumosintes and 11 resistance genes were studied by PCR. P. gingivalis fimA genotype was determined.

Results

In healthy patients, P. micra and P. intermedia were the most and least frequently detected, respectively. T. forsythia and E. corrodens appeared in 100 % of gingivitis patients. Red complex, D. pneumosintes and E. corrodens were significantly more prevalent in CP compared to healthy patients. F. nucleatum and T. denticola were detected more frequently in AgP. A. actinomycetemcomitans was the most rarely observed in all groups. The fimA II genotype was the most prevalent in periodontitis patients. Seven tetracycline-resistant genes were detected. tet(Q), tet(32) and tet(W) showed the greatest prevalence. tet(32) was significantly more prevalent in CP than in healthy patients.

Conclusions

Red complex bacteria and D. pneumosintes were significantly the most prevalent species among periodontitis patients. T. forsythia was the most frequently detected in this population. To our knowledge, this is the first study describing the tet(32) gene in subgingival biofilm from healthy and periodontally diseased subjects.

Clinical relevance

This study contributes to the knowledge on the subgingival microbiota and its resistance genes of a scarcely studied world region. Knowing the prevalence of resistance genes could impact on their clinical prescription and could raise awareness to the appropriate use of antibiotics.

Electronic supplementary material

The online version of this article (doi:10.1007/s00784-015-1516-2) contains supplementary material, which is available to authorized users.

The Tetracycline Destructases: A Novel Family of Tetracycline-Inactivating Enzymes

Enzymes capable of inactivating tetracycline are paradoxically rare compared with enzymes that inactivate other natural-product antibiotics. We describe a family of flavoenzymes, previously unrecognizable as resistance genes, which are capable of degrading tetracycline antibiotics. From soil functional metagenomic selections, we discovered nine genes that confer high-level tetracycline resistance by enzymatic inactivation. We also demonstrate that a tenth enzyme, an uncharacterized homolog in the human pathogen Legionella longbeachae, similarly inactivates tetracycline. These enzymes catalyze the oxidation of tetracyclines in vitro both by known mechanisms and via previously undescribed activity. Tetracycline-inactivation genes were identified in diverse soil types, encompass substantial sequence diversity, and are adjacent to genes implicated in horizontal gene transfer. Because tetracycline inactivation is scarcely observed in hospitals, these enzymes may fill an empty niche in pathogenic organisms, and should therefore be monitored for their dissemination potential into the clinic.

Genomic Comparison of Non-Typhoidal Salmonella enterica Serovars Typhimurium, Enteritidis, Heidelberg, Hadar and Kentucky Isolates from Broiler Chickens

BACKGROUND

Non-typhoidal Salmonella enterica serovars, associated with different foods including poultry products, are important causes of bacterial gastroenteritis worldwide. The colonization of the chicken gut by S. enterica could result in the contamination of the environment and food chain. The aim of this study was to compare the genomes of 25 S. enterica serovars isolated from broiler chicken farms to assess their intra- and inter-genetic variability, with a focus on virulence and antibiotic resistance characteristics.

METHODOLOGY/PRINCIPAL FINDING

The genomes of 25 S. enterica isolates covering five serovars (ten Typhimurium including three monophasic 4,[5],12:i:, four Enteritidis, three Hadar, four Heidelberg and four Kentucky) were sequenced. Most serovars were clustered in strongly supported phylogenetic clades, except for isolates of serovar Enteritidis that were scattered throughout the tree. Plasmids of varying sizes were detected in several isolates independently of serovars. Genes associated with the IncF plasmid and the IncI1 plasmid were identified in twelve and four isolates, respectively, while genes associated with the IncQ plasmid were found in one isolate. The presence of numerous genes associated with Salmonella pathogenicity islands (SPIs) was also confirmed. Components of the type III and IV secretion systems (T3SS and T4SS) varied in different isolates, which could explain in part, differences of their pathogenicity in humans and/or persistence in broilers. Conserved clusters of genes in the T3SS were detected that could be used in designing effective strategies (diagnostic, vaccination or treatments) to combat Salmonella. Antibiotic resistance genes (CMY, aadA, ampC, florR, sul1, sulI, tetAB, and srtA) and class I integrons were detected in resistant isolates while all isolates carried multidrug efflux pump systems regardless of their antibiotic susceptibility profile.

CONCLUSIONS/SIGNIFICANCE

This study showed that the predominant Salmonella serovars in broiler chickens harbor genes encoding adhesins, flagellar proteins, T3SS, iron acquisition systems, and antibiotic and metal resistance genes that may explain their pathogenicity, colonization ability and persistence in chicken. The existence of mobile genetic elements indicates that isolates from a given serovar could acquire and transfer genetic material. Conserved genes in the T3SS and T4SS that we have identified are promising candidates for identification of diagnostic, antimicrobial or vaccine targets for the control of Salmonella in broiler chickens.

Pattern of multiresistant to antimicrobials and heavy metal tolerance in bacteria isolated from sewage sludge samples from a composting process at a recycling plant in southern Brazil

The composting process is a viable alternative for the recycling of household organic waste and sewage sludge generated during wastewater treatment. However, this technique can select microorganisms resistant to antimicrobials and heavy metals as a result of excess chemicals present in compost windrow. This study evaluates the antimicrobial multiresistant and tolerance to heavy metals in bacteria isolated from the composting process with sewage sludge. Fourteen antimicrobials were used in 344 strains for the resistance profile and four heavy metals (chromium, copper, zinc, and lead) for the minimum biocide concentration assay. The strains used were from the sewage sludge sample (beginning of the process) and the compost sample (end of the process). Strains with higher antimicrobial and heavy metal profile were identified by 16S rRNA gene sequencing. The results showed a multiresistant profile in 48 % of the strains, with the highest percentage of strains resistant to nitrofurantoin (65 %) and β-lactams (58 %). The strains isolated from the sewage sludge and the end of the composting process were more tolerant to copper, with a lethal dose of approximately 900 mg L(-1) for about 50 % of the strains. The genera that showed the highest multiresistant profile and increased tolerance to the metals tested were Pseudomonas and Ochrobactrum. The results of this study may contribute to future research and the revision and regulation of legislation on sewage sludge reuse in soils.

Intensified food production and correlated risks to human health in the Greater Mekong Subregion: a systematic review

BACKGROUND

Intensified food production, i.e. agricultural intensification and industrialized livestock operations may have adverse effects on human health and promote disease emergence via numerous mechanisms resulting in either direct impacts on humans or indirect impacts related to animal and environmental health. For example, while biodiversity is intentionally decreased in intensive food production systems, the consequential decrease in resilience in these systems may in turn bear increased health risks. However, quantifying these risks remains challenging, even if individual intensification measures are examined separately. Yet, this is an urgent task, especially in rapidly developing areas of the world with few regulations on intensification measures, such as in the Greater Mekong Subregion (GMS).

METHODS

We systematically searched the databases PubMed and Scopus for recent studies conducted on the association between agricultural (irrigation, fertilization, pesticide application) and livestock (feed additives, animal crowding) intensification measures and human health risks in the GMS. The search terms used were iteratively modified to maximize the number of retrieved studies with relevant quantitative data.

RESULTS

We found that alarmingly little research has been done in this regard, considering the level of environmental contamination with pesticides, livestock infection with antibiotic resistant pathogens and disease vector proliferation in irrigated agroecosystems reported in the retrieved studies. In addition, each of the studies identified focused on specific aspects of intensified food production and there have been no efforts to consolidate the health risks from the simultaneous exposures to the range of hazardous chemicals utilized.

CONCLUSIONS

While some of the studies identified already reported environmental contamination bearing considerable health risks for local people, at the current state of research the actual consolidated risk from regional intensification measures cannot be estimated. Efforts in this area of research need to be rapidly and considerably scaled up, keeping pace with the current level of regional intensification and the speed of pesticide and drug distribution to facilitate the development of agriculture related policies for regional health promotion.

Global trends in antimicrobial use in food animals

Demand for animal protein for human consumption is rising globally at an unprecedented rate. Modern animal production practices are associated with regular use of antimicrobials, potentially increasing selection pressure on bacteria to become resistant. Despite the significant potential consequences for antimicrobial resistance, there has been no quantitative measurement of global antimicrobial consumption by livestock. We address this gap by using Bayesian statistical models combining maps of livestock densities, economic projections of demand for meat products, and current estimates of antimicrobial consumption in high-income countries to map antimicrobial use in food animals for 2010 and 2030. We estimate that the global average annual consumption of antimicrobials per kilogram of animal produced was 45 mg⋅kg(-1), 148 mg⋅kg(-1), and 172 mg⋅kg(-1) for cattle, chicken, and pigs, respectively. Starting from this baseline, we estimate that between 2010 and 2030, the global consumption of antimicrobials will increase by 67%, from 63,151 ± 1,560 tons to 105,596 ± 3,605 tons. Up to a third of the increase in consumption in livestock between 2010 and 2030 is imputable to shifting production practices in middle-income countries where extensive farming systems will be replaced by large-scale intensive farming operations that routinely use antimicrobials in subtherapeutic doses. For Brazil, Russia, India, China, and South Africa, the increase in antimicrobial consumption will be 99%, up to seven times the projected population growth in this group of countries. Better understanding of the consequences of the uninhibited growth in veterinary antimicrobial consumption is needed to assess its potential effects on animal and human health.

Antimicrobial use in Chinese swine and broiler poultry production

BACKGROUND

Antimicrobial use for growth promotion in food animal production is now widespread. A major concern is the rise of antimicrobial resistance and the subsequent impact on human health. The antimicrobials of concern are used in concentrated animal feeding operations (CAFOs) which are responsible for almost all meat production including swine and poultry in the US. With global meat consumption rising, the CAFO model has been adopted elsewhere to meet this demand. One such country where this has occurred is China, and evidence suggests 70% of poultry production now occurs outside of traditional small farms. Moreover, China is now the largest aggregate consumer of meat products in the world. With this rapid rise in consumption, the Chinese production model has changed along with the use of antimicrobials in feeds. However, the specific antibiotic use in the Chinese food animal production sector is unclear. Additionally, we are aware of high quantities of antimicrobial use because of reports of high concentrations of antimicrobials in animal waste and surface waters surrounding animal feeding operations.

METHODS

In this report, we estimate the volume of antibiotics used for swine and poultry production as these are the two meat sources with the highest levels of production and consumption in China. We adopt a model developed by Mellon et al. in the US for estimating drug use in feed for poultry and swine production to estimate overall antimicrobial use as well as antimicrobial use by class.

RESULTS

We calculate that 38.5 million kg [84.9 million lbs] were used in 2012 in China's production of swine and poultry. By antibiotic class, the highest weights are tetracyclines in swine and coccidiostats in poultry.

CONCLUSIONS

The volume of antimicrobial use is alarming. Although there are limitations to these data, we hope our report will stimulate further analysis and a sense of urgency in assessing the consequences of such high levels of utilization in terms of antibiotic resistance in the food supply and the environment.

Exploitation of plasmin(ogen) by bacterial pathogens of veterinary significance

The plasminogen (Plg) system plays an important homeostatic role in the degradation of fibrin clots, extracellular matrices and tissue barriers important for cellular migration, as well as the promotion of neurotransmitter release. Plg circulates in plasma at physiologically high concentrations (150-200μg ml(-1)) as an inactive proenzyme. Proteins enriched in lysine and other positively charged residues (histidine and arginine) as well as glycosaminoglycans and gangliosides bind Plg. The binding interaction initiates a structural adjustment to the bound Plg that facilitates cleavage by proteases (plasminogen activators tPA and uPA) that activate Plg to the active serine protease plasmin. Both pathogenic and commensal bacteria capture Plg onto their cell surface and promote its conversion to plasmin. Many microbial Plg-binding proteins have been described underpinning the importance this process plays in how bacteria interact with their hosts. Bacteria exploit the proteolytic capabilities of plasmin by (i) targeting the mammalian fibrinolytic system and degrading fibrin clots, (ii) remodeling the extracellular matrix and generating bioactive cleavage fragments of the ECM that influence signaling pathways, (iii) activating matrix metalloproteinases that assist in the destruction of tissue barriers and promote microbial metastasis and (iv) destroying immune effector molecules. There has been little focus on the exploitation of the fibrinolytic system by veterinary pathogens. Here we describe several pathogens of veterinary significance that possess adhesins that bind plasmin(ogen) onto their cell surface and promote its activation to plasmin. Cumulative data suggests that these attributes provide pathogenic and commensal bacteria with a means to colonize and persist within the host environment.