Antimicrobial use and resistance in animals

Antibiotic resistance and virulence of Escherichia coli strains isolated from animal rendering plant

Processing of animal carcasses and other animal wastes in rendering plants is a significant source of antibiotic resistant microorganisms. The main goal of this study was to investigate the resistance to 18 antibacterial agents including β-lactams, fluoroquinolones, colistin and virulence factors (iss, tsh, cvaC, iutA, papC, kps and ibeA genes) in 88 Escherichia coli strains isolated from a rendering plant over 1 year period. ESBL (Extended-spectrum beta-lactamases) and plasmid-mediated Amp were screened by interpretative reading of MIC. ESBL phenotype was detected in 20.4% of samples and high level of resistance to fluoroquinolone was found in 27.2% of strains. Cephalosporinase CTX-M1, cephamycinase CMY-2, integrase 1 and transposon 3 genes were detected by PCR. Furthermore, there were found three CMY-2 producing E. coli with O25b-ST131, resistant to the high level of enrofloxacin and containing the gene encoding the ferric aerobactin receptor (iutA). One enrofloxacin resistant E. coli strain possessed iss, ibeA, kps and papC virulence genes also with CMY-2, integrase1 and Tn3. ST131 E. coli with CMY-2 has a zoonotic potential and presents a serious health risk to humans.

Enhanced Antibacterial Activity of Silver Nanoparticles Combined with Hydrogen Peroxide Against Multidrug-Resistant Pathogens Isolated from Dairy Farms and Beef Slaughterhouses in Egypt

Purpose

The last few decades have witnessed a rapid and global increase in multidrug-resistant bacteria (MDR) emergence.

Methods

The aim of the current study is to isolate the most common MDR bacteria from dairy farms and beef slaughterhouses followed by evaluation of their antimicrobial resistance pattern and assessment of the antibacterial activity of AgNPs-H₂O₂ as an alternative to conventional antibiotics. In this regard, 200 samples were collected from two dairy farms and one beef slaughterhouse located in Dakhliya Governorate, Egypt.

Results

Interestingly, out of 120 collected samples from dairy farms, the prevalence of the isolated strains was 26.7, 23.3, 21.7, 16.7, and 11.7% for S. typhimurium, E. coli O157:H7, L. monocytogenes, K. pneumoniae and P. aeruginosa, respectively. Meanwhile, the overall prevalence was 30, 25, 22.5, 17.5, and 5% for E. coli O157:H7, L. monocytogenes, S. typhimurium, P. aeruginosa, and K. pneumoniae, respectively, for the 80 samples collected from a beef slaughterhouse. The antimicrobial susceptibility pattern elucidated that all isolated strains exhibited resistance to at least four of the tested antimicrobials, with multiple-antibiotic resistance index values (MAR) ranging between 0.44 and 0.88. Furthermore, the commercial AgNPs-H₂O₂ product was characterized by transmission electron microscopy (TEM) and zeta potential that showed spherical particles with a surface charge of -0.192 mV. The antimicrobial activity of synergized nano-silver (AgNP) with H₂O₂ product toward MDR strains was assessed via measuring minimum inhibitory concentration (MIC), minimum bactericidal concentration (MBC), and time-kill curve.

Conclusion

The present data report high prevalence rates of MDR pathogens in dairy farms and abattoirs. More importantly, AgNPs-H₂O₂ exerted broad-spectrum bactericidal activity toward MDR bacterial strains, suggesting their promising usage as safe, ecofriendly, cost-effective antibacterial agents. To our knowledge, this study is a pioneer in investigating the potential alternative antimicrobial role of silver nanoparticles for control of multiple drug-resistant pathogens in Egypt.

Understanding Antibiotic Residues and Pathogens Flow in Wastewater from Smallholder Pig Farms to Agriculture Field in Ha Nam Province, Vietnam

BACKGROUND

Contact with livestock wastewater on farms and in communities can pose a risk to human and animal health.

METHODS

This cross-sectional study was conducted in 180 households and 24 pig farms (96 wastewater samples) to explore information about pig production, livestock waste management, antibiotic use, and to analyze antibiotic residues and microbial contamination, respectively.

RESULTS

Of the 120 households raising pigs, biogas systems were the most commonly used to treat animal waste (70%), followed by compositing (19%), and the remaining respondents discharged waste directly into drains or ponds (11%). The majority of respondents (78%) used antibiotics to treat and prevent disease in pigs, but 32% of them did not know of any disadvantages of antibiotic abuse. ELISA assays were performed on half of the wastewater samples (n = 48), demonstrating that residues of flouroquinolones and sulfonamides were present in 6.3% (3/48) and 22.9% (11/48) of tested samples, respectively. The average residual level of sulfamethazine was 27.8 ug/l. Further, E. coli concentrations exceeding regulatory levels in Vietnam were found in nearly all samples. Salmonella spp. was also found in 57.3% of samples, though prevalence rates varied across the different sites. Finally, G. lamblia was found in 8.4% of samples, and C. parvum was found in 5.2% of samples.

CONCLUSIONS

This study suggests that livestock wastewater carried potential harmful pathogens and antibiotic residues that could come into contact with humans in the community. Thus, appropriate operation and application of livestock wastewater treatment (such as biogas or composting) and management should be a continued focused.

Effects of concentrated poultry operations and cropland manure application on antibiotic resistant Escherichia coli and nutrient pollution in Chesapeake Bay watersheds

Manure from poultry operations is typically applied to nearby cropland and may affect nutrient loading and the spread of antibiotic resistance (ABR). We analyzed the concentrations of nitrogen and phosphorus and the occurrence of ABR in Escherichia coli (E. coli) and extra-intestinal pathogenic E. coli isolates from streams draining 15 small (<19 km²) watersheds of the Chesapeake Bay with contrasting levels of concentrated poultry operations. Total nitrogen and nitrate plus nitrite concentrations increased with poultry barn density with concentrations two and three times higher, respectively, in watersheds with the highest poultry barn densities compared to those without poultry barns. Analysis of N and O isotopes in nitrate by mass spectrometry showed an increase in the proportion of ¹⁵N associated with an increase in barn density, suggesting that the nitrate associated with poultry barns originated from manure. Phosphorus concentrations were not correlated with barn density. Antibiotic susceptibility testing of putative E. coli isolates was conducted using the disk diffusion method for twelve clinically important antibiotics. Of the isolates tested, most were completely susceptible (67%); 33% were resistant to at least one antibiotic, 24% were resistant to ampicillin, 13% were resistant to cefazolin, and 8% were multi-drug resistant. Resistance to three cephalosporin drugs was positively associated with an index of manure exposure estimated from poultry barn density and proportion of cropland in a watershed. The proportion of E. coli isolates resistant to cefoxitin, cefazolin, and ceftriaxone, broad-spectrum antibiotics important in human medicine, increased by 18.9%, 16.9%, and 6.2%, respectively, at the highest estimated level of manure exposure compared to watersheds without manure exposure. Our results suggest that comparisons of small watersheds could be used to identify geographic areas where remedial actions may be needed to reduce nutrient pollution and the public health risks of ABR bacteria.

Influence of vaccination of broiler chickens against Escherichia coli with live attenuated vaccine on general properties of E. coli population, IBV vaccination efficiency, and production parameters-a field experiment

Poultry colibacillosis has been one of the major causes behind economic losses in the poultry production; however, no effective method for its prevention has been developed so far. Vaccination against colibacillosis is capturing increasing interest. The aim of this study was to demonstrate benefits from using a live, aroA gene–deleted vaccine against colibacillosis in broiler chickens and its potential impact on reduced use of antibiotics, the efficacy of vaccination against infectious bronchitis (IB), and the structure and properties of Escherichia coli population in broilers under commercial farm conditions. In 2 experiments, carried out on 3 farms, broiler chickens of one chicken house from each farm were vaccinated against Escherichia coli (E. coli), whereas birds of other chicken houses of each farm were not vaccinated against E. coli. In experiment 1, which was carried out on 2 farms, for 3 consecutive production cycles, spray vaccination of day-old broilers against E. coli decreased the number of E. coli isolates from internal organs but not from the respiratory system in the sixth week of birds' life. In experiment 1, E. coli–vaccinated broilers did not receive the antimicrobials until 14 d after the vaccination. Escherichia coli isolates from the E. coli–vaccinated birds were more susceptible to the antimicrobials. Escherichia coli vaccination had no impact on the IB vaccination efficiency; it has reduced the mean number of days of the antimicrobial treatment and improved broiler production parameters. In experiment 2, chickens of both houses received the antimicrobials for the first 4 d of their life. Birds of chicken house 1 were vaccinated against E. coli on the ninth day of life, whereas birds of chicken house 2 were not vaccinated. In both houses, further antimicrobial usage was the same, and antimicrobials were not used until 14 d after E. coli vaccination. Similar to experiment 1, in experiment 2, vaccination decreased the number of E. coli isolates, and these isolates were more susceptible to the antimicrobials. Vaccination of broilers against E. coli should be considered in terms of routine immunoprophylaxis.

Prevalence of Multidrug-Resistant Foodborne Pathogens and Indicator Bacteria from Edible Offal and Muscle Meats in Nashville, Tennessee

This study investigated the prevalence of antimicrobial-resistant bacteria in retail edible offal and muscle meats in Nashville, Tennessee. A total of 348 retail meats (160 edible offal and 188 muscle) were analyzed for Salmonella enterica serovar, Campylobacter, Escherichia coli, E. coli O157:H7, and enterococci. Bacteria was identified using biochemical and PCR methods. Salmonella enterica serovar (4.4% and 4.3%), Campylobacter (1.9% and 1.1%), E. coli (79.4% and 89.4%), and enterococci (88.1% and 95.7%) was detected in offal and muscle meats, respectively. Chicken liver (9.7%) was most frequently contaminated with Salmonella enterica serovar, followed by ground chicken (6.9%) and chicken wings (4.2%). No Salmonella enterica serovar was detected in beef liver, beef tripe, and ground beef. The prevalence of Campylobacter was 6.9%, 2.3%, and 1.4% in beef liver, ground beef, and ground chicken, respectively. None of the meats were positive for E. coli O157:H7. Resistance of isolates was significantly (p < 0.05) highest in erythromycin (98.3%; 99.1%), followed by tetracycline (94%; 98.3%), vancomycin (88.8%; 92.2%) as compared to chloramphenicol (43.1%; 53.9%), amoxicillin/clavulanic (43.5%; 45.7%), and ciprofloxacin (45.7%; 55.7%) in offal and muscle meats, respectively. Imipenem showed the lowest resistance (0%; 0.9%). A total of 41 multidrug-resistant patterns were displayed. Edible offal could be a source of antibiotic-resistant bacteria.

Antimicrobial resistance pattern in domestic animal - wildlife - environmental niche via the food chain to humans with a Bangladesh perspective; a systematic review

BACKGROUND

Antimicrobial resistance (AMR) is a growing concern globally, but the impact is very deleterious in the context of Bangladesh. Recent review article on the AMR issue demonstrates the scenario in human medicine; unfortunately, no attempt was taken to address this as One Health issue. The antimicrobial resistance bacteria or genes are circulating in the fragile ecosystems and disseminate into human food chain through direct or indirect ways. In this systematic review we are exploring the mechanism or the process of development of resistance pathogen into human food chain via the domestic animal, wildlife and environmental sources in the context of One Health and future recommendation to mitigate this issue in Bangladesh.

RESULTS

Tetracycline resistance genes were presenting in almost all sample sources in higher concentrations against enteric pathogen Escherichia coli. The second most significant antibiotics are amino-penicillin that showed resistant pattern across different source of samples. It is a matter of concerns that cephalosporin tends to acquire resistance in wildlife species that might be an indication of this antibiotic resistance gene or the pathogen been circulating in our surrounding environment though the mechanism is still unclear.

CONCLUSIONS

Steps to control antibiotic release and environmental disposal from all uses should be immediate and obligatory. There is a need for detailed system biology analysis of resistance development in-situ.

Association of antimicrobial usage with faecal abundance of aph(3')-III, ermB, sul2 and tetW resistance genes in veal calves in three European countries

BACKGROUND

High antimicrobial use (AMU) and antimicrobial resistance (AMR) in veal calves remain a source of concern. As part of the EFFORT project, the association between AMU and the abundance of faecal antimicrobial resistance genes (ARGs) in veal calves in three European countries was determined.

METHODS

In 2015, faecal samples of veal calves close to slaughter were collected from farms located in France, Germany and the Netherlands (20 farms in France, 20 farms in the Netherlands and 21 farms in Germany; 25 calves per farm). Standardized questionnaires were used to record AMU and farm characteristics. In total, 405 faecal samples were selected for DNA extraction and quantitative polymerase chain reaction to quantify the abundance (16S normalized concentration) of four ARGs [aph(3')-III, ermB, sul2 and tetW] encoding for resistance to frequently used antimicrobials in veal calves. Multiple linear mixed models with random effects for country and farm were used to relate ARGs to AMU and farm characteristics.

RESULTS

A significant positive association was found between the use of trimethoprim/sulfonamides and the concentration of sul2 in faeces from veal calves. A higher weight of calves on arrival at the farm was negatively associated with aph(3')-III and ermB. Lower concentrations of aph(3')-III were found at farms with non-commercial animals present. Furthermore, farms using only water for the cleaning of stables had a significantly lower abundance of faecal ermB and tetW compared with other farms.

CONCLUSION

A positive association was found between the use of trimethoprim/sulfonamides and the abundance of sul2 in faeces in veal calves. Additionally, other relevant risk factors associated with ARGs in veal calves were identified, such as weight on arrival at the farm and cleaning practices.

The incidence of antibiotic resistance within and beyond the agricultural ecosystem: A concern for public health

The agricultural ecosystem creates a platform for the development and dissemination of antimicrobial resistance, which is promoted by the indiscriminate use of antibiotics in the veterinary, agricultural, and medical sectors. This results in the selective pressure for the intrinsic and extrinsic development of the antimicrobial resistance phenomenon, especially within the aquaculture‐animal‐manure‐soil‐water‐plant nexus. The existence of antimicrobial resistance in the environment has been well documented in the literature. However, the possible transmission routes of antimicrobial agents, their resistance genes, and naturally selected antibiotic‐resistant bacteria within and between the various niches of the agricultural environment and humans remain poorly understood. This study, therefore, outlines an overview of the discovery and development of commonly used antibiotics; the timeline of resistance development; transmission routes of antimicrobial resistance in the agro‐ecosystem; detection methods of environmental antimicrobial resistance determinants; factors involved in the evolution and transmission of antibiotic resistance in the environment and the agro‐ecosystem; and possible ways to curtail the menace of antimicrobial resistance.

High-Throughput Detection and Characterization of Antimicrobial Resistant Enterococcus sp. Isolates from GI Tracts of European Starlings Visiting Concentrated Animal Feeding Operations

Antimicrobial resistant enteric bacteria can easily contaminate the environment and other vehicles through the deposition of human and animal feces. In turn, humans can be exposed to these antimicrobial resistant (AMR) bacteria through contaminated food products and/or contaminated drinking water. As wildlife are firmly established as reservoirs of AMR bacteria and serve as potential vectors in the constant spread of AMR, limiting contact between wildlife and livestock and effective tracking of AMR bacteria can help minimize AMR dissemination to humans through contaminated food and water. Enterococcus spp., which are known opportunistic pathogens, constantly found in gastrointestinal tracts of mammalian and avian species, swiftly evolve and cultivate AMR genotypes and phenotypes, which they easily distribute to other bacteria, including several major bacterial pathogens. In this study, we evaluated the use of high throughput detection and characterization of enterococci from wildlife [European starlings (Sturnus vulgaris)] by matrix-assisted laser desorption ionization time-of-flight mass spectrometry (MALDI-TOF MS) following culture-based isolation. MALDI-TOF MS successfully identified 658 Enterococcus spp. isolates out of 718 presumptive isolates collected from gastrointestinal tracts of European starlings, which were captured near livestock operations in Colorado, Iowa, Kansas, Missouri, and Texas; antimicrobial susceptibility testing was then performed using 13 clinically significant antibiotics.

Some aspects of the acute phase immune response to a lipopolysaccharide (LPS) challenge are mitigated by supplementation with a Saccharomyces cerevisiae fermentation product in weaned beef calves

This study was conducted to determine if feeding a Saccharomyces cerevisiae fermentation product (SCFP) to calves would alter the acute phase response to a lipopolysaccharide (LPS) challenge. Crossbred steer calves [n = 32; 274 ± 1.9 kg body weight (BW)] were randomly allotted to two treatment diets for 21 d: 1) control, fed RAMP (Cargill, Dalhart, TX) and 2) SCFP, fed the control ration supplemented with NaturSafe at 12 g/hd/d mixed into the TMR (NaturSafe, Diamond V, Cedar Rapids, IA). On day 22, steers were fitted with indwelling jugular catheters and rectal temperature monitoring devices and placed in individual bleeding stalls. On day 23, steers were challenged i.v. with 0.25 µg/kg BW LPS. Blood samples were collected at 0.5-h (serum) or 2-h (complete blood counts) intervals from -2 to 8 h and again at 24 h relative to the LPS challenge at 0 h. Sickness behavior scores (SBS) were recorded after the collection of each blood sample. Rectal temperatures were greater in SCFP steers from 6 to 11 h, at 13 h, from 15 to 20 h, and from 22 to 24 h following the LPS challenge compared to Control steers (treatment × time: P = 0.01). Additionally, SCFP-supplemented steers had reduced (P < 0.01) SBS compared to Control steers. Platelet concentrations remained greater in SCFP-supplemented steers compared to Control steers throughout the study (P = 0.05), while there was a tendency (P = 0.09) for SCFP steers to have greater white blood cells and eosinophils concentrations than Control steers. There was a treatment × time interaction for serum cortisol and glucose (P < 0.01). Specifically, cortisol was greater at 0.5 and 2 h postchallenge but was reduced at 3 h for SCFP steers compared to Control steers. Glucose was greater in SCFP steers at -0.5, 2, and 7.5 h compared to Control steers. Serum amyloid A was reduced in SCFP steers at 0.5 h, yet greater at 1 and 7.5 h postchallenge compared to Control steers (treatment × time: P < 0.01). Fibrinogen concentrations were greater (P < 0.01) in SCFP compared to Control steers. There was a treatment × time interaction (P < 0.01) for tumor necrosis factor-α (TNF-α) such that concentrations were reduced in SCFP steers from 1 to 2 h postchallenge compared to Control steers. Overall, these data suggest that supplementing calves with SCFP may have primed the innate immune response prior to the challenge, particularly platelets, which resulted in an attenuated sickness behavior and TNF-α response to LPS.

Bird-livestock interactions associated with increased cattle fecal shedding of ciprofloxacin-resistant Escherichia coli within feedlots in the United States

This research study was conducted to determine if bird depredation in feedlots is associated with the prevalence of ciprofloxacin-resistant Escherichia coli in cattle and to determine if removal of invasive bird species could be an effective management strategy to help reduce ciprofloxacin-resistant E. coli in cattle within the United States. European starlings (Sturnus vulgaris) were collected from feedlots within multiple geographic regions within the United States and European starlings within all regions tested positive for ciprofloxacin-resistant E. coli, but prevalence differed by region. Total number of birds on feedlots were positively associated with increased cattle fecal shedding of ciprofloxacin-resistant E. coli. Targeted control of invasive European starlings reduced bird numbers on feedlots by 70.4%, but decreasing populations of European starlings was not associated with corresponding reductions in bovine fecal prevalence of ciprofloxacin-resistant E. coli. These data provide evidence for the role of wild bird depredation in feedlots contributing to fecal shedding of ciprofloxacin-resistant E. coli, but a single month of European starling control in feedlots was not sufficient to impact the fecal carriage of this organism in cattle.

Application of median lethal concentration (LC50) of pathogenic microorganisms and their antigens in vaccine development

OBJECTIVE

Lack of ideal mathematical models to qualify and quantify both pathogenicity, and virulence is a dreadful setback in development of new antimicrobials and vaccines against resistance pathogenic microorganisms. Hence, the modified arithmetical formula of Reed and Muench has been integrated with other formulas and used to determine bacterial colony forming unit/viral concentration, virulence and immunogenicity.

RESULTS

Microorganisms' antigens tested are Staphylococcus aureus, Streptococcus pneumoniae, Pseudomonas aeruginosa in mice and rat, Edwardsiella ictaluri, Aeromonas hydrophila, Aeromonas veronii in fish, New Castle Disease virus in chicken, Sheep Pox virus, Foot-and-Mouth Disease virus and Hepatitis A virus in vitro, respectively. The LC50s for the pathogens using different routes of administrations are 1.93 × 103(sheep poxvirus) and 1.75 × 1010 for Staphylococcus aureus (ATCC29213) in rat, respectively. Titer index (TI) equals N log10 LC50 and provides protection against lethal dose in graded fashion which translates to protection index. N is the number of vaccine dose that could neutralize the LC50. Hence, parasite inoculum of 103 to 1011 may be used as basis for determination of LC50 and median bacterial concentrations (BC50).Pathogenic dose for immune stimulation should be sought at concentration about LC10.

Microcin J25 Exhibits Inhibitory Activity Against Salmonella Newport in Continuous Fermentation Model Mimicking Swine Colonic Conditions

Microcin J25 (MccJ25), a 21-amino acid bacteriocin produced by Escherichia coli (E. coli), is a potent inhibitor of Enterobacteriaceae, including pathogenic E. coli, Salmonella, and Shigella. Its lasso structure makes it highly stable and therefore of interest as a possible antimicrobial agent in foods or as an alternative to antibiotics in livestock production. In the present study, we aimed to evaluate in vitro the inhibitory activity of MccJ25 against Salmonella enterica subsp. enterica serovar Newport ATCC 6962 (Salmonella Newport) used as a model pathogen under conditions simulating those of the swine proximal colon. The growth inhibition activity of MccJ25 against Salmonella Newport was examined in lysogeny broth (LB) and in modified MacFarlane medium that allows miming the swine colonic conditions. The MccJ25 activity was further determined using the Polyfermentor intestinal model (PolyFermS), an in vitro continuous fermentation model that permits deciphering the activity of any antimicrobial molecule in real colon fermentation conditions using selected microbiota. It was set up here to simulate the porcine proximal colon fermentation. In these conditions, the inhibition activity of MccJ25 was compared to those of two antimicrobial agents, reuterin and rifampicin. The minimal inhibitory concentration (MIC) of MccJ25 was determined at 0.03 μM in LB medium, compared to 1,079 and 38 μM for reuterin and rifampicin, respectively, showing a significantly higher potency of MccJ25. Total inhibition of Salmonella Newport was observed in LB medium over 24 h of incubation at concentrations starting from the MIC. In the PolyFermS model, MccJ25 induced a significantly stronger inhibition of Salmonella Newport growth than reuterin or rifampicin. A specific and sensitive LC-MS method allowed to detect and quantify MccJ25 in the PolyFermS fermentation system, showing that MccJ25 remains stable and active against Salmonella in conditions mimicking those found in swine colon. This study paves the way for further exploring the potential of this bacteriocin as an alternative to antibiotics in livestock.

Poor mental health of livestock farmers in Africa: a mixed methods case study from Ghana

Background

Agriculture represents the mainstay of African economies and livestock products are essential to the human population’s nutritional needs. However, in many developing countries, including Ghana, livestock production fails to meet demand due to population growth and negative effects of climate change. One of the challenges to production is livestock loss affecting farmers. However, despite stressful events experienced, livestock farmers’ mental health is poorly documented. This study aims to identify the root causes of livestock losses and their influence on pastoralists’ mental health.

Methods

We conducted a mixed methods study in two districts in the Northern and Southern Belts of Ghana. Using the Depression Anxiety and Stress Scale–21 and guided interviews, we collected quantitative and qualitative data from 287 livestock farmers and 24 key-informants respectively. Mental health scores were categorized using standard guidelines. We evaluated the factors that explained variations in mental wellbeing using general linear models (α = 0.05).

Results

About 85% (240/287) of the livestock farmers lost cattle within 1 year. Of these, 91% lost cattle to animal diseases, 50% to theft and 27% to pasture shortages. Qualitative findings reveal that due to poor access to veterinary services, farmers treat livestock diseases themselves with drugs from unregulated sources and often sell diseased cows for meat to recover losses. Findings showed that 60% of livestock farmers had poor mental health. Of those, 72% were depressed, 66% anxious and 59% stressed. Mental wellbeing was negatively associated with the number of adverse events experienced, proportion of livestock lost to most of the major loss factors, emotional attachment to livestock and self-reported physical illnesses in farmers, but positively associated with increasing herd size [F (8,278) = 14.18, p < 0.001, R² = 0.29].

Conclusions

Livestock diseases are the leading cause of losses to livestock farmers, whose mental wellbeing is negatively affected by these losses. Although an adaptive strategy by farmers to compensate for poor veterinary services, the arbitrary use of veterinary drugs and sale of diseased cattle pose health risks to the public. Further research to evaluate the performance of veterinary services in Ghana, mental health problems and risk to human health due to potential high-risk meat entering the food chain, is needed.

Evolution of Salmonella enterica serotype Typhimurium driven by anthropogenic selection and niche adaptation

Salmonella enterica serotype Typhimurium (S. Typhimurium) is a leading cause of gastroenteritis and bacteraemia worldwide, and a model organism for the study of host-pathogen interactions. Two S. Typhimurium strains (SL1344 and ATCC14028) are widely used to study host-pathogen interactions, yet genotypic variation results in strains with diverse host range, pathogenicity and risk to food safety. The population structure of diverse strains of S. Typhimurium revealed a major phylogroup of predominantly sequence type 19 (ST19) and a minor phylogroup of ST36. The major phylogroup had a population structure with two high order clades (α and β) and multiple subclades on extended internal branches, that exhibited distinct signatures of host adaptation and anthropogenic selection. Clade α contained a number of subclades composed of strains from well characterized epidemics in domesticated animals, while clade β contained multiple subclades associated with wild avian species. The contrasting epidemiology of strains in clade α and β was reflected by the distinct distribution of antimicrobial resistance (AMR) genes, accumulation of hypothetically disrupted coding sequences (HDCS), and signatures of functional diversification. These observations were consistent with elevated anthropogenic selection of clade α lineages from adaptation to circulation in populations of domesticated livestock, and the predisposition of clade β lineages to undergo adaptation to an invasive lifestyle by a process of convergent evolution with of host adapted Salmonella serotypes. Gene flux was predominantly driven by acquisition and recombination of prophage and associated cargo genes, with only occasional loss of these elements. The acquisition of large chromosomally-encoded genetic islands was limited, but notably, a feature of two recent pandemic clones (DT104 and monophasic S. Typhimurium ST34) of clade α (SGI-1 and SGI-4).

Development and selection of low-level multi-drug resistance over an extended range of sub-inhibitory ciprofloxacin concentrations in Escherichia coli

To better combat bacterial antibiotic resistance, a growing global health threat, it is imperative to understand its drivers and underlying biological mechanisms. One potential driver of antibiotic resistance is exposure to sub-inhibitory concentrations of antibiotics. This occurs in both the environment and clinic, from agricultural contamination to incorrect dosing and usage of poor-quality medicines. To better understand this driver, we tested the effect of a broad range of ciprofloxacin concentrations on antibiotic resistance development in Escherichia coli. We observed the emergence of stable, low-level multi-drug resistance that was both time and concentration dependent. Furthermore, we identified a spectrum of single mutations in strains with resistant phenotypes, both previously described and novel. Low-level class-wide resistance, which often goes undetected in the clinic, may allow for bacterial survival and establishment of a reservoir for outbreaks of high-level antibiotic resistant infections.

Antimicrobial Resistance Pattern of Escherichia coli Isolated from Frozen Chicken Meat in Bangladesh

Escherichia coli is known as one of the most important foodborne pathogens in humans, and contaminated chicken meat is an important source of foodborne infection with this bacterium. The occurrence of extended-spectrum β-lactamase (ESBL)-producing E. coli (ESBL-Ec), in particular, in chicken meat is considered a global health problem. This study aimed to determine the magnitude of E. coli, with special emphasis on ESBL-Ec, along with their phenotypic antimicrobial resistance pattern in frozen chicken meat. The study also focused on the determination of ESBL-encoding genes in E. coli. A total of 113 frozen chicken meat samples were purchased from 40 outlets of nine branded supershops in five megacities in Bangladesh. Isolation and identification of E. coli were done based on cultural and biochemical properties, as well as PCR assay. The resistance pattern was determined by the disc diffusion method. ESBL-encoding genes were determined by multiplex PCR. The results showed that 76.1% of samples were positive for E. coli, of which 86% were ESBL producers. All the isolates were multidrug-resistant (MDR). Resistance to 9-11 and 12-13 antimicrobial classes was observed in 38.4% and 17.4% isolates, respectively, while only 11.6% were resistant to 3-5 classes. Possible extensive drug resistance (pXDR) was found in 2.3% of isolates. High single resistance was observed for oxytetracycline (93%) and amoxicillin (91.9%), followed by ampicillin (89.5%), trimethoprim-sulfamethoxazole, and pefloxacin (88.4%), and tetracycline (84.9%). Most importantly, 89.6% of isolates were resistant to carbapenems. All the isolates were positive for the blaTEM gene. However, the blaSHV and blaCTX-M-2 genes were identified in two ESBL-non producer isolates. None of the isolates carried the blaCTX-M-1 gene. This study provided evidence of the existence of MDR and pXDR ESBL-Ec in frozen chicken meat in Bangladesh, which may pose a risk to human health if the meat is not properly cooked or pickled raw only. This emphasizes the importance of the implementation of good slaughtering and processing practices by the processors.

A systematic review of the efficacy of antibiotics for the prevention of swine respiratory disease

Prevention and control of respiratory disease is a major contributor to antibiotic use in swine. A systematic review was conducted to address the question, 'What is the comparative efficacy of antimicrobials for the prevention of swine respiratory disease?' Eligible studies were controlled trials published in English evaluating prophylactic antibiotics in swine, where clinical morbidity, mortality, or total antibiotic use was assessed. Four databases and the gray literature were searched for relevant articles. Two reviewers working independently screened titles and abstracts for eligibility followed by full-text articles, and then extracted data and evaluated risk of bias for eligible trials. There were 44 eligible trials from 36 publications. Clinical morbidity was evaluated in eight trials where antibiotics were used in nursery pigs and 10 trials where antibiotics were used in grower pigs. Mortality was measured in 22 trials in nursery pigs and 12 trials in grower pigs. There was heterogeneity in the antibiotic interventions and comparisons published in the literature; thus, there was insufficient evidence to allow quantification of the efficacy, or relative efficacy, of antibiotic interventions. Concerns related to statistical non-independence and quality of reporting were noted in the included trials.

Antimicrobial resistance genes in bacteria from animal-based foods

Antimicrobial resistance is a worldwide public health threat. Farm animals are important sources of bacteria containing antimicrobial resistance genes (ARGs). Although the use of antimicrobials in aquaculture and livestock has been reduced in several countries, these compounds are still routinely applied in animal production, and contribute to ARGs emergence and spread among bacteria. ARGs are transmitted to humans mainly through the consumption of products of animal origin (PAO). Bacteria can present intrinsic resistance, and once antimicrobials are administered, this resistance may be selected and multiply. The exchange of genetic material is another mechanism used by bacteria to acquire resistance. Some of the main ARGs found in bacteria present in PAO are the bla, mcr-1, cfr and tet genes, which are directly associated to antibiotic resistance in the human clinic.

Use of antimicrobials in beef cattle: an observational study in the north of Italy

Antimicrobial resistance is a worldwide issue whereby a more prudent use of medications is needed, especially for those antimicrobials (AM) classified as 'highest priority critically important antimicrobials' (HPCIAs) which are likely contributors to the development of resistance. So far, data on antimicrobial use (AMU) in EU are mainly reported at sales level while information on real use, mostly in beef production, is poor. The most reliable indicator to measure AMU is the treatment incidence (TI100) calculated by using the Defined Daily Dose Animal (DDDA) as stated by the European Medicines Agency (EMA). Although Italy ranks second among EU countries with regard to the AM sales in livestock production, data on AMU of the Italian beef production is still lacking, whereby the aim of this study was to provide information on the current scenario of AMU in Italian beef cattle. Data were collected from January 2016 to April 2019 from specialized beef fattening farms located in the north of Italy yielding a final dataset of 1376 batches. Data on performance and AM agents used in the study were collected and TI100 indexes per batch were calculated according to both Italian and EMA's DDDA. A Kruskal-Wallis test was used to check for differences between years and seasons. Results showed a significant variation between years and seasons with a reduction of TI100 based on Italian DDDA as time progressed (P < 0.05). However, about 40% of the total amount of treatments administered were HPCIAs with macrolides accounting for the 27.7% of the total amount. The most common reasons of administration of AM were respiratory diseases (68.9%) and lameness (17.6%). Penicillins was the class of AM used on the highest proportion of batches (84.4%) showing that broad-spectrum AM were widely exploited among herds. In summary, despite a general reduction of AMU in beef cattle over time, a great use of HPCIAs was still observed suggesting that AM stewardship for Italian beef production should pay particular emphasis on the reduction of HPCIAs use. This shows how overall knowledge on where efforts need to be optimized is important to develop targeted strategies for a more responsible AM stewardship. Results of the current study may also contribute to define national and EU benchmark criteria for AMU, as a comparison with studies carried out in other countries or on other food-producing sectors is still challenging to achieve.

Toward Antibiotic Stewardship: Route of Antibiotic Administration Impacts the Microbiota and Resistance Gene Diversity in Swine Feces

Oral antibiotics are a critical tool for fighting bacterial infections, yet their use can have negative consequences, such as the disturbance of healthy gut bacterial communities and the dissemination of antibiotic residues in feces. Altering antibiotic administration route may limit negative impacts on intestinal microbiota and reduce selective pressure for antimicrobial resistance genes (ARG) persistence and mobility. Thus, a study was performed in pigs to evaluate route of therapeutic oxytetracycline (oxytet) administration, an antibiotic commonly used in the U.S. swine industry, on intestinal microbial diversity and ARG abundance. Given that oral antibiotics would be in direct contact with intestinal bacteria, we hypothesized that oral administration would cause a major shift in intestinal bacterial community structure when compared to injected antibiotic. We further postulated that the impact would extend to the diversity and abundance of ARG in swine feces. At approximately 3 weeks-of-age, piglets were separated into three groups (n = 21–22 per group) with two groups receiving oxytet (one via injection and the second via feed) and a third non-medicated group. Oxytet levels in the plasma indicated injected antibiotic resulted in a spike 1 day after administration, which decreased over time, though oxytet was still detected in plasma 14 days after injection. Conversely, in-feed oxytet delivery resulted in lower but less variable oxytet levels in circulation and high concentrations in feces. Similar trends were observed in microbial community changes regardless of route of oxytet administration; however, the impact on the microbial community was more pronounced at all time points and in all samples with in-feed administration. Fecal ARG abundance was increased with in-feed administration over injected, with genes for tetracycline and aminoglycoside resistance enriched specifically in the feces of the in-feed group. Sequencing of plasmid-enriched samples revealed multiple genetic contexts for the resistance genes detected and highlighted the potential role of small plasmids in the movement of antibiotic resistance genes. The findings are informative for disease management in food animals, but also manure management and antibiotic therapy in human medicine for improved antibiotic stewardship.

Weaning affects the glycosidase activity towards phenolic glycosides in the gut of piglets

Phenolic compounds in pig diets, originating either from feed ingredients or additives, may occur as glycosides, that is conjugated to sugar moieties. Upon ingestion, their bioavailability and functionality depend on hydrolysis of the glycosidic bond by endogenous or microbial glycosidases. Hence, it is essential to map the glycosidase activities towards phenolic glycosides present along gut. Therefore, the activity of three key glycosidases, that is α-glucosidase (αGLU), β-glucosidase (βGLU) and β-galactosidase (βGAL), was quantified in small intestinal mucosa and digesta of piglets at different gastrointestinal sites (stomach, three parts of small intestine, caecum and colon) and at different ages around weaning (10 days before and 0, 2, 5, 14 and 28 days after weaning). Activity assays were performed with p-nitrophenyl glycosides at neutral pH. The αGLU activities in mucosa and digesta were low (overall means 1.4 and 60 U respectively) as compared to βGLU (15.2 and 199 U) and βGAL (23.4 and 298 U; p < .001). Moreover, αGLU activity in mucosa was unaffected by age. Conversely, βGLU and βGAL activities dropped significantly after weaning. Minimal levels, ranging between 18% and 54% of the pre-weaning values, were reached at 5 days post-weaning. Similarly, in small intestinal digesta, reductions from 60% up to 90% were observed for the three enzyme activities on day five post-weaning as compared to pre-weaning levels. In caecal contents, activities were lowest at 14 days post-weaning, while in stomach and colon no clear weaning-induced effects were observed. Our data suggest that weaning affects the glycosidase activity in mucosa (mainly endogenous origin) and digesta (primarily bacterial origin) with the most pronounced effects occurring 5 days post-weaning. Moreover, differences in activities exist between different glycosidases and between gut locations. These insights can facilitate the prediction of the fate of existing and newly synthetized glycosides after oral ingestion in piglets.

The technical and economic impact of veterinary interventions aimed at reducing antimicrobial use on broiler farms

Antimicrobial resistance is a global threat for both human and animal health. One of the main drivers of antimicrobial resistance is inappropriate antimicrobial use in livestock production. The aim of this study was to examine the technical and economic impact of tailor-made interventions, aimed at reducing antimicrobial use in broiler production. Historical (i.e., before intervention) and observational (i.e., after intervention) data were collected at 20 broiler farms. Results indicate that average daily gain and mortality generally increased after intervention, whereas feed conversion and antimicrobial use decreased. Economic performance after interventions was generally higher than before the interventions. Sensitivity analyses on price changes confirm the robustness of the findings.

A critical review on antibiotics and hormones in swine wastewater: Water pollution problems and control approaches

Swine wastewater (SW) is an important source of antibiotics and hormones (A&H) in the environment due to their large-scale application in swine industry. A&H in SW can be released into the water environment through the direct discharge of SW, effluent from SW treatment plants, and runoff and leaching from farmland polluted by swine wastes. The presence of A&H in the water environment has become an increasing global concern considering their adverse effects to the aquatic organism and human. This review critically discusses: (i) the occurrence of A&H in global water environment and their potential risks to water organisms and human; (ii) the management and technical approaches for reducing the emission of A&H in SW to the water environment. The development of antibiotic alternatives and the enhanced implementation of vaccination and biosecurity are promising management approaches to cut down the consumption of antibiotics during swine production. Through the comparison of different biological treatment technologies for removing A&H in SW, membrane-based bioprocesses have relatively higher and more stable removal efficiencies. Whereas, the combined system of bioprocesses and AOPs is expected to be a promising technology for elimination and mineralization of A&H in swine wastewater. Further study on this system is therefore necessary.

Antimicrobial Resistance in Veterinary Medicine: An Overview

Antimicrobial resistance (AMR) represents one of the most important human- and animal health-threatening issues worldwide. Bacterial capability to face antimicrobial compounds is an ancient feature, enabling bacterial survival over time and the dynamic surrounding. Moreover, bacteria make use of their evolutionary machinery to adapt to the selective pressure exerted by antibiotic treatments, resulting in reduced efficacy of the therapeutic intervention against human and animal infections. The mechanisms responsible for both innate and acquired AMR are thoroughly investigated. Commonly, AMR traits are included in mobilizable genetic elements enabling the homogeneous diffusion of the AMR traits pool between the ecosystems of diverse sectors, such as human medicine, veterinary medicine, and the environment. Thus, a coordinated multisectoral approach, such as One-Health, provides a detailed comprehensive picture of the AMR onset and diffusion. Following a general revision of the molecular mechanisms responsible for both innate and acquired AMR, the present manuscript focuses on reviewing the contribution of veterinary medicine to the overall issue of AMR. The main sources of AMR amenable to veterinary medicine are described, driving the attention towards the indissoluble cross-talk existing between the diverse ecosystems and sectors and their cumulative cooperation to this warning phenomenon.

Occurrence and Characteristics of Mobile Colistin Resistance (mcr) Gene-Containing Isolates from the Environment: A Review

The emergence and spread of mobile colistin (COL) resistance (mcr) genes jeopardize the efficacy of COL, a last resort antibiotic for treating deadly infections. COL has been used in livestock for decades globally. Bacteria have mobilized mcr genes (mcr-1 to mcr-9). Mcr-gene-containing bacteria (MGCB) have disseminated by horizontal/lateral transfer into diverse ecosystems, including aquatic, soil, botanical, wildlife, animal environment, and public places. The mcr-1, mcr-2, mcr-3, mcr-5, mcr-7, and mcr-8 have been detected in isolates from and/or directly in environmental samples. These genes are harboured by Escherichia coli, Enterobacter, Klebsiella, Proteus, Salmonella, Citrobacter, Pseudomonas, Acinetobacter, Kluyvera, Aeromonas, Providencia, and Raulotella isolates. Different conjugative and non-conjugative plasmids form the backbones for mcr in these isolates, but mcr have also been integrated into the chromosome of some strains. Insertion sequences (IS) (especially ISApl1) located upstream or downstream of mcr, class 1–3 integrons, and transposons are other drivers of mcr in the environment. Genes encoding multi-/extensive-drug resistance and virulence are often co-located with mcr on plasmids in environmental isolates. Transmission of mcr to/among environmental strains is clonally unrestricted. Contact with the mcr-containing reservoirs, consumption of contaminated animal-/plant-based foods or water, international animal-/plant-based food trades and travel, are routes for transmission of MGCB.

Development of a green fluorescence protein (GFP)-based bioassay for detection of antibiotics and its application in milk

Antibiotics are one of the most widely used types of drugs in pharmaceutics. However, efficiency of these drugs has decreased recently owing to the threat of antibiotic resistance. One of the important factors causing antibiotic resistance is the excessive use of antibacterials in animals. Therefore, detection of antibiotics in foods of animal origin is crucial. The aim of this study was to develop a novel whole-cell based bioassay to be used for detection of some antibiotics. Green fluorescent protein (GFP)-expressing Escherichia coli cells were used as a recognition agent, and antibiotic detection was carried out by pursuing the inhibition rate of fluorescence intensity as a result of the inhibition of viable cells by the time of progress. The performance of bioassay was tested for different antibiotics, and the obtained results showed that the developed method can be used successfully for detection of ampicillin, benzylpenicillin, gentamicin, neomycin, and tetracycline with the limit of detection (LOD) values of 3.33, 0.29, 28.00, 618.36, and 33.17 µg/L, respectively. The assay was also tested with antibiotic spiked milk samples (skimmed UHT, full-fat UHT, and whole raw milk). According to obtained recovery values, developed method was successful for all samples. The precision and bias values of the method were found between the range of 1.30% to 7.54% and -8.00% to 0.64%, respectively. The developed method, which is inexpensive and simple with detection limits in line with the regulatory limits, is promising for use in milk quality monitoring. Method has potential to be used as a screening method after comprehensive validation. PRACTICAL APPLICATION: This method could be used in animal husbandry to check whether the antibiotic prescribed for the treatment of sick animals is still present in their milk as residual. For dairy industry, detection of residual antibiotics in milk is crucial because of their inhibition effects on the fermentation processes. Therefore, the proposed method can be used for routine analysis of raw milk reception in dairy industries. In addition, it is considered to have a wide range of applications for all foods.

The relation between technical farm performance and antimicrobial use of broiler farms

The aim of the present study was to explore the relation between both farm performance and antimicrobial use (AMU) of broiler farms. Farm performance was expressed as technical efficiency, obtained by using a bootstrap data envelopment analysis. AMU was expressed as treatment incidence. Cluster analysis is used to obtain groups of farms with similar characteristics regarding technical farm performance and AMU. Results indicate that the farms within the different clusters combine different technical farm performance and different levels of AMU. Between the clusters, significant differences were found in technical farm performance, AMU, the resource intensity of the number of animals at set-up, the number of antimicrobial treatments, the number of antimicrobial treatments related to either gut health or combined problems, and the number of antimicrobial treatments with either yellow or orange active substances. Farmers who combine high levels of AMU with high technical farm performance are likely to overestimate the real economic value of AMU. Proper coordination between the farmer and the veterinarian can be crucial in that case for reducing AMU. Farms with low performance are likely to have poor farm conditions. Improving those farm conditions can help reducing the need for AMU on this kind of farms. The farm-specific conditions have to be considered in future policies aimed at reducing AMU in livestock production.

Prevalence and antimicrobial-resistance phenotypes and genotypes of Escherichia coli isolated from raw milk samples from mastitis cases in four regions of China

OBJECTIVES

The objective was to find the differences in the prevalence and resistance of Escherischia coli isolated from raw milk samples from mastitis cases in four regions of China.

METHODS

A total of 750 bovine raw milk samples from mastitis cases were collected from four regions of China over two seasons. Antimicrobial resistance against 29 antimicrobial agents was determined, and 27 drug-resistant genes were tested.

RESULTS

Eighty-three strains (11.1%) of E. coli were isolated and identified. No significant differences in the number of E. coli isolates were observed between the two sampling seasons in the same regions (P>0.05). However, a significant difference in E. coli prevalence was found among the four different regions (P<0.01). The isolates were most frequently resistant to penicillin (100%), acetylspiramycin (100%), lincomycin (98.8%), oxacillin (98.8%) and sulphamethoxazole (53%). All the E. coli strains were multiresistant to at least three antimicrobial classes, and the most frequent multidrug-resistance patterns for the isolates were resistant to three (36.1%) or four (39.8%) classes of drugs simultaneously. The blaTEM gene (n=69; 83.1%) was the most frequently detected resistance gene. The most frequent gene combinations were a four-gene pattern of blaCTX-M-sulII-blaTEM-sulI (n=13; 15.7%) and a three-gene pattern of blaCTX-M-aph (3)-II-blaTEM (n=11; 13.3%).

CONCLUSIONS

This study indicated that there is a high incidence of E. coli with a great variation in resistance patterns and resistance genes; this is a matter of great concern for public and animal health in China.

Bactericidal Effect of Clove Oil against Multidrug-Resistant Streptococcus suis Isolated from Human Patients and Slaughtered Pigs

Streptococcus suis is a zoonotic pathogen that is currently considered an emerging multidrug-resistant (MDR). Increasing antibiotic resistance can lead to the unsuccessful treatment of S. suis infection. Recently, many investigations of medicinal plants were conducted for the treatment of infection as a result of the increase of antibiotic-resistant bacteria. The aims of this study were to determine the chemical composition of essential oil from Syzygium aromaticum (L.) Merr. & L.M. Perry and the antibacterial activities of clove oil on MDR S. suis. Using gas chromatography coupled to a mass spectrometer, eugenol (97.76%) was found to be the major active ingredient of clove oil. In vitro antibacterial activities of clove oil against MDR S. suis were evaluated. Using the agar disc diffusion test, the clove oil showed a maximum zone of inhibition at 15% (v/v) oil concentration. In a broth microdilution method, the minimum bactericidal concentration of clove oil against all MDR S. suis isolates was 0.1% (v/v). A time-kill analysis was performed, and the killing kinetics of clove oil showed that MDR S. suis was completely reduced after 15 min of exposure to clove oil. In addition, clove oil exhibited a strong antibacterial activity at all pH values applied following incubation of MDR S. suis in pH-adjusted media with clove oil. Moreover, scanning electron microscopy revealed the nonviable S. suis isolates clearly showed atypical form and cell membrane lysis after incubation with clove oil. This study confirms the efficacy of clove oil as a natural antimicrobial against MDR S. suis and suggests the possibility of employing it as a promising alternative product for control of infectious diseases caused by S. suis in animal and human patients.

Effects of Dietary Chicory (Chicorium intybus L.) and Probiotic Blend as Natural Feed Additives on Performance Traits, Blood Biochemistry, and Gut Microbiota of Broiler Chickens

The experiment was designed to determine the effect of different levels of chicory (Chicorium intybus L.) powder and a probiotic blend (PrimaLac^®) on productive performance, blood biochemical parameters, and ileal microbiota in broiler chickens. A total of 225 one-day-old broilers (Ross 308) were used in a completely randomized design with five experimental diets as follows: 1—basal-diet without supplements (control-group); 2—basal-diet including probiotic blend; 3— basal-diet including 0.10% chicory; 4—basal-diet including 0.15% chicory; 5—basal-diet including 0.20% chicory. At 42 days of age, representative birds per replicate were randomly selected for blood samples and carcass measurements. Results showed that the body weight gain of broilers fed the probiotic blend or 0.10% chicory was significantly (P < 0.05) higher than those fed on the other treatments. The abdominal fat pad was significantly (P < 0.05) lower in birds fed diets including chicory compared with control or probiotic. Blood triglycerides and LDL levels were reduced (P < 0.05) and HDL increased (P < 0.05) when fed probiotic or chicory whereas no significant effect on the other serum parameters was found. Broiler ileal microflora from the control group had significantly (P < 0.05) higher count of E. coli and lower Lactobacillus than those from the other groups. From findings, it is possible to conclude that dietary chicory powder supported positively growth performance and improved gut microbiota in broiler chickens. However, more research is needed on this subject to better understand the mode of action of feed additives used.

Dissecting the Antimicrobial Composition of Honey

Honey is a complex sweet food stuff with well-established antimicrobial and antioxidant properties. It has been used for millennia in a variety of applications, but the most noteworthy include the treatment of surface wounds, burns and inflammation. A variety of substances in honey have been suggested as the key component to its antimicrobial potential; polyphenolic compounds, hydrogen peroxide, methylglyoxal and bee-defensin 1. These components vary greatly across honey samples due to botanical origin, geographical location and secretions from the bee. The use of medical grade honey in the treatment of surface wounds and burns has been seen to improve the healing process, reduce healing time, reduce scarring and prevent microbial contamination. Therefore, if medical grade honeys were to be included in clinical treatment, it would reduce the demand for antibiotic usage. In this review, we outline the constituents of honey and how they affect antibiotic potential in a clinical setting. By identifying the key components, we facilitate the development of an optimally antimicrobial honey by either synthetic or semisynthetic production methods.

Biosecurity practices in Belgian veal calf farming: Level of implementation, attitudes, strengths, weaknesses and constraints

The shift from cure toward prevention in veterinary medicine involves the implementation of biosecurity. In cattle farming, the application of biosecurity measures has been described to a limited degree, yet no data on biosecurity on veal farms is available. A high degree of commingling of veal calves from multiple farms causes frequent disease outbreaks, and thereby high antimicrobial usage and increased risk of antimicrobial resistance. Therefore, this study aimed to describe the current implementation of biosecurity on veal farms in Belgium. To this extent, a list of the most important calf diseases (n = 34) was created, and risk factors and related biosecurity measures for these diseases were determined and included in a questionnaire. Herd visits and face-to-face interviews were conducted on 20 randomly selected veal farms, comprising 8.3% of the target population. A categorical principal component and clustering analysis were performed to determine the influence of the veal companies on the farms' biosecurity level. Awareness of biosecurity was very low among the farmers. All farms used an "all-in, all-out" production system with calves originating from multiple farms without quarantine. On average, farms were filled in 11.4 days (range 2-52). The degree of commingling for these farms was 1.24, meaning that, on average, 124 calves originated from 100 farms. Veterinarians wore farm-specific boots on eight farms (40%) and farm-specific clothes on six farms (30%), while technical advisors wore farm-specific boots on six farms (30%) and farm-specific clothes on four farms (20%). Disinfection footbaths were only used in five farms (25%) despite being present in all farms in the sample. Concerning internal biosecurity, none of the farmers isolated sick animals; only one farmer (5%) had a physically separated hospital pen, and only 11 farmers (55%) both cleaned and disinfected the stables after each production cycle. In most farms, animals were of comparable age. Healthy calves generally remained in the same compartment during the entire production cycle, limiting the risks associated with the movement of animals. No influence of the integrations on the biosecurity level could be determined. It can be concluded that a few biosecurity measures, such as "'all-in, all-out" and compartmentation, are implemented relatively well, while other measures, such as good cleaning and disinfection and proper entrance measures for visitors and personnel can easily be improved. The improvement of measures regarding the introduction of animals of different origins will require more fundamental changes in the veal industry.

PA. Review of Antibiotic Resistance, Ecology, Dissemination, and Mitigation in U.S. Broiler Poultry Systems

Since the onset of land application of poultry litter, transportation of microorganisms, antibiotics, and disinfectants to new locations has occurred. While some studies provide evidence that antimicrobial resistance (AMR), an evolutionary phenomenon, could be influenced by animal production systems, other research suggests AMR originates in the environment from non-anthropogenic sources. In addition, AMR impacts the effective prevention and treatment of poultry illnesses and is increasingly a threat to global public health. Therefore, there is a need to understand the dissemination of AMR genes to the environment, particularly those directly relevant to animal health using the One Health Approach. This review focuses on the potential movement of resistance genes to the soil via land application of poultry litter. Additionally, we highlight impacts of AMR on microbial ecology and explore hypotheses explaining gene movement pathways from U.S. broiler operations to the environment. Current approaches for decreasing antibiotic use in U.S. poultry operations are also described in this review.

Bacterial antibiotic resistance development and mutagenesis following exposure to subminimal inhibitory concentrations of fluoroquinolones in vitro: a systematic literature review protocol

INTRODUCTION

Antibiotic resistance (AR) is among the most pressing global health challenges. Fluoroquinolones are a clinically important group of antibiotics that have wide applicability in both humans and animals. While many drivers of AR are known, the impact of medicine quality on AR remains largely unknown. The aim of this review is to systematically evaluate the evidence of the impact of in vitro subinhibitory antibiotic exposure, a major tenet of substandard antibiotics, on the development of AR and mutagenesis, using fluoroquinolones as a case study.

METHODS AND ANALYSIS

EMBASE, Web of Science and PubMed will be systematically searched for primary experimental in vitro studies, from earliest available dates within each database (1947, 1965 and 1966, respectively) through 2018, related to subinhibitory fluoroquinolone exposure and AR. A specifically developed non-weighted tool will be used to critically assess the evidence. Subgroup analyses will be performed for different variables and outcomes.

ETHICS AND DISSEMINATION

Ethical approval is not required as no primary data are to be collected. The completed systematic review will be disseminated through conference meeting presentations and a peer-reviewed publication.

In vitro and in vivo Synergistic Effects of Florfenicol and Thiamphenicol in Combination Against Swine Actinobacillus pleuropneumoniae and Pasteurella multocida

Potential synergism between florfenicol (FF) and thiamphenicol (TAP) was investigated for in vitro efficacy against Actinobacillus pleuropneumoniae and/or Pasteurella multocida as well as in vivo efficacy in swine. Among isolates of A. pleuropneumoniae (n = 58) and P. multocida (n = 79) from pigs in Taiwan that were tested, high percentages showed resistance to FF (52 and 53%, respectively) and TAP (57 and 53%, respectively). Checkerboard microdilution assay indicated that synergism [fractional inhibitory concentration index (FICI) ≤ 0.5] was detected in 17% of A. pleuropneumoniae (all serovar 1) and 24% of P. multocida isolates. After reconfirming the strains showing FICI ≤ 0.625 with time kill assay, the synergism increased to around 32% against both bacteria and the number could further increase to 40% against resistant A. pleuropneumoniae and 65% against susceptible P. multocida isolates. A challenge-treatment trial in pigs with P. multocida showed that the FF + TAP dosage at ratios correspondent to their MIC deduction was equally effective to the recommended dosages. Further on the combination, the resistant mutation frequency is very low when A. pleuropneumoniae is grown with FF + TAP and similar to the exposure to sub-inhibitory concentration of FF or TAP alone. The degree of minimum inhibitory concentration (MIC) reduction in FF could reach 75% (1/4 MIC) or more (up to 1/8 MIC for P. multocida, 1/16 for A. pleuropneumoniae) when combined with 1/4 MIC of TAP (or 1/8 for A. pleuropneumoniae). The synergism or FICI ≤ 0.625 of FF with oxytetracycline (47%), doxycycline (69%), and erythromycin (56%) was also evident, and worth further investigation for FF as a central modulator facilitating synergistic effects with these antimicrobials. Taken together, synergistic FF + TAP combination was effective against swine pulmonary isolates of A. pleuropneumoniae and P. multocida both in vitro and in vivo. Thus, this study may offer a potential alternative for the treatment of A. pleuropneumoniae and P. multocida infections and has the potential to greatly reduce drug residues and withdrawal time.

Microbial diversity and antibiotic resistome in swine farm environments

Swine feedlots are recognized as a reservoir of antibiotic resistance genes (ARGs). However, the microbiome and antibiotic resistome in swine wastewater and its impact on receiving environments remain to be further explored by culture independent metagenomics. We investigated the microbial diversity of swine wastewater and the receiving environments in three swine farms by 16S rRNA gene sequencing. Metagenomic sequencing was utilized to further study the antibiotic resistome in the different depths of soils in vegetable fields, which had been fertilized with swine wastewater for at least 24 years. The 16S rRNA gene sequencing showed that the microbiome of the well water, fishpond, vegetables and the field soils was affected by the respective swine farms. Significant positive correlations were found between 20 ARGs and 41 genus of bacteria across all environmental samples. The metagenomic sequencing showed that a total of 79 types of ARGs were found in soil cores (at depth of 0-20 cm, 20-40 cm and 40-70 cm) and the irrigation water (swine wastewater). Antibiotics were detected in vertical soil profiles and wastewater. Compared with the vegetable fields without animal manure application, the soils irrigated with swine wastewater harbored higher diversity of ARGs and contained higher concentrations of antibiotics. Co-occurrence of integron-related scaffolds was found in different depths of soil cores and the swine wastewater. The results suggest that environmental microbiome was changed under the impact of swine farms, and long-term manure/wastewater application have resulted in the accumulation of ARGs in deeper soils Prudent use of antibiotics and reasonable management of animal wastes in livestock feedlots should therefore be considered to reduce the dissemination of antibiotic resistance to the environment.

A survey of free-range egg farmers in the United Kingdom: Knowledge, attitudes and practices surrounding antimicrobial use and resistance

Antimicrobial resistance (AMR) is a significant global challenge affecting human health and attention has been drawn to practices of all stakeholders involved in antimicrobial prescription and administration, including in the livestock sector. This survey of free-range egg farmers (n = 117) was conducted to investigate knowledge, attitudes and practices surrounding antimicrobial use, and identify farmer-led solutions towards responsible antimicrobial use. Most participants proved knowledgeable of AMR and selected treatments based on principles of responsible medicine use. 'Worms' and 'infectious diseases' were the most common reasons for medicine use. Farms with a higher number of poultry houses, younger flock ages at depopulation and farms visited by a vet less than once a year or 3-4 times a year (compared to annually or twice a year) were more likely to select 'ANTIBIOTICS ONLY', as opposed to 'BOTH ANTIBIOTICS AND ANTIPARASITICS' or 'ANTIPARASITICS ONLY' as their most frequently used medicines. Participants from farms with a younger flock age at depopulation, from company-owned farms, and participants purchasing medicines from agricultural merchants instead of veterinary practices were less likely to be taking measures to reduce or replace antimicrobial use. Participants from larger farms and those that had less contact with their vet were less likely to think that they could reduce or replace the amount of antibiotics used. Survey results provided evidence for the important role of veterinarians in guiding antimicrobial stewardship through engagement, collaboration and education. Discussion groups in which farmers share best practices could assist the free-range egg industry in further promoting responsible antimicrobial use.

Antimicrobial use policy change in pre-weaned dairy calves and its impact on antimicrobial resistance in commensal Escherichia coli: a cross sectional and ecological study

Background

This study is based on data collected to investigate the relation of peri-parturient events (colostrum quality, passive transfer of immunity, calving difficulty) on calf health and antimicrobial use. A component of the study was to provide feedback to farm management to identify calves at risk for disease and promote antimicrobial stewardship. At the start of the study (May 2016), a combination of enrofloxacin, penicillin, and sulfamethoxazole was the first treatment given to clinically abnormal calves. Based on feedback and interaction between study investigators, farm management and consulting veterinarians, a new policy was implemented to reduce antimicrobial use in calves. In August, the first treatment was changed to a combination of ampicillin and sulfamethoxazole. In September, the first treatment was reduced to only sulfamethoxazole. We investigated the effects of these policy changes in antimicrobial use on resistance in commensal Escherichia coli.

Results

We enrolled 4301 calves at birth and documented antimicrobial use until weaning. Most calves (99.4%) received antimicrobials and 70.4% received a total of 2–4 treatments. Antimicrobial use was more intense in younger calves (≤ 28 days) relative to older calves. We isolated 544 E. coli from fecal samples obtained from 132 calves. We determined resistance to 12 antimicrobials and 85% of the isolates were resistant to at least 3 antimicrobial classes. We performed latent class analysis to identify underlying unique classes where isolates shared resistance patterns and selected a solution with 4 classes. The least resistant class had isolates that were mainly resistant to only tetracycline and sulfisoxazole. The other 3 classes comprised isolates with resistance to ampicillin, chloramphenicol, aminoglycosides, sulfonamides, tetracycline, in addition to either ceftiofur; or nalidixic acid; or ciprofloxacin plus nalidixic acid and ceftiofur. Overall, E coli from younger calves and calves that received multiple treatments were more likely to have extensive resistance including resistance to fluoroquinolones and ceftiofur. In general, there was a declining trend in resistance to most antimicrobials during and after policy changes were implemented, except for ampicillin, ciprofloxacin, ceftiofur and gentamicin.

Conclusions

Information feedback to farms can influence farm managers to reduce antimicrobial use and this can change endemic farm resistance patterns.

Electronic supplementary material

The online version of this article (10.1186/s12866-019-1576-6) contains supplementary material, which is available to authorized users.

Characterization of a Linezolid- and Vancomycin-Resistant Streptococcus suis Isolate That Harbors optrA and vanG Operons

Linezolid and vancomycin are among the last-resort antimicrobial agents in the treatment of multidrug-resistant Gram-positive bacterial infections. Linezolid- and vancomycin-resistant (LVR) Gram-positive bacteria may pose severe threats to public health. In this study, three optrA- and vanG-positive Streptococcus suis strains were isolated from two farms of different cities. There were only 1 and 343 single-nucleotide polymorphisms in coding region (cSNPs) of HCB4 and YSJ7 to YSJ17, respectively. Mobilome analysis revealed the presence of vanG, erm(B), tet(O/W/32/O), and aadE-apt-sat4-aphA3 cluster on an integrative and conjugative element, ICESsuYSJ17, and erm(B), aphA3, aac(6')-aph(2″), catpC₁₉₄, and optrA on a prophage, ΦSsuYSJ17-3. ICESsuYSJ17 exhibited a mosaic structure and belongs to a highly prevalent and transferable ICESa2603 family of Streptococcus species. ΦSsuYSJ17-3 shared conserved backbone to a transferable prophage Φm46.1. A novel composite transposon, IS1216E-araC-optrA-hp-catpC₁₉₄-IS1216E, which can be circulated as translocatable unit (TU) by IS1216E, was integrated on ΦSsuYSJ17-3. Vancomycin resistance phenotype and vanG transcription assays revealed that the vanG operon was inducible. The LVR strain YSJ17 exhibited moderate virulence in a zebrafish infection model. To our knowledge, this is the first report of LVR isolate, which is mediated by acquired resistance genes optrA and vanG operons in Gram-positive bacteria. Since S. suis has been recognized as an antimicrobial resistance reservoir in the spread of resistance genes to major streptococcal pathogens, the potential risks of disseminating of optrA and vanG from S. suis to other Streptococcus spp. are worrisome and routine surveillance should be strengthened.

Antimicrobial resistance in Campylobacter jejuni and Campylobacter coli isolated from small poultry flocks in Ontario, Canada: A two-year surveillance study

Antimicrobial resistance in Campylobacter, common in poultry, is a global public health issue. The emergence and spread of antimicrobial resistant Campylobacter has been linked to the use of antimicrobials in food animals. Small poultry flocks are becoming increasingly popular not only as a source of food but also as pets, yet not all small flock owners are aware of proper antimicrobial use practices and safe food handling protocols. This trend could contribute to antimicrobial resistance. In order to determine the prevalence of antimicrobial resistance in Campylobacter in small poultry flocks, we analyzed data from birds that had been submitted to a diagnostic laboratory in Ontario between October 2015 and September 2017. A pooled cecal sample was obtained from each submission and cultured for Campylobacter jejuni and Campylobacter coli. Three isolates were recovered from each positive sample and tested for susceptibility to nine antimicrobials using a broth microdilution method. Overall, 176 isolates were recovered (141 chicken, 21 turkey, 6 duck, and 8 game bird). A high frequency of resistance to tetracycline was observed in the C. jejuni isolates from chickens (77%) and turkeys (100%), and in the C. coli isolates from turkeys (50%) and game birds (40%). Campylobacter jejuni isolates had higher odds of resistance to tetracycline (OR = 3.54, P ≤ 0.01) compared to C. coli isolates. Overall, there was a low frequency of resistance to quinolones and a very low frequency of resistance to macrolides. Multidrug resistance was uncommon. The high prevalence of tetracycline resistance emphasizes the importance of prudent antimicrobial use in small flocks. Although low, the presence of resistance to macrolides and quinolones, which are used to treat campylobacteriosis in humans, highlights the need for proper food safety and infection control practices by small flock owners to prevent exposure to antimicrobial resistant Campylobacter.

A simple and rapid sensing strategy based on structure-switching signaling aptamers for the sensitive detection of chloramphenicol

A simple and rapid sensing strategy was proposed for chloramphenicol (CAP) detection based on structure-switching signaling aptamers. In this protocol, the aptamer can bind to both the fluorophore (FAM)-labeled complementary strand and the quencher (BHQ1)-labeled complementary strand, thus leading to the effective quenching of FAM fluorescence by BHQ1. However, when CAP is present, the structure switch is reversed because the aptamer recognizes CAP, resulting in fluorescence recovery. Such a fluorescence-sensing platform can monitor CAP within a good linear range (1-100 ng/mL), with a detection limit of 0.70 ng/mL. Cross-reactivity with other common antibiotics is negligible, indicating the excellent selectivity of the strategy. Moreover, as the aptamers are not modified, this method is simple and low-cost. The present work reveals a new direction for detecting CAP or other target compounds without prior knowledge of the secondary or tertiary structures of the aptamer.

Antibiotic use in food animals worldwide, with a focus on Africa: Pluses and minuses

Antibiotics are frequently used in food animal production in developing countries to promote the well-being and growth of animals. This practice provides some economic benefits to producers and consumers at large. Nevertheless, this practice is also associated with a number of concerns. A major concern has been that repeatedly exposing these animals to small doses of antibiotics contributes significantly to antimicrobial resistance, since a good fraction of the antibiotics used are the same or surrogates of antibiotics used in human therapeutic practices. Studies over decades have shown an explicit relationship between antimicrobial use and antimicrobial resistance in veterinary science. Many antibiotics can be purchased over the counter in African countries, and antibiotic resistance is an important issue to address in this region. This review examines some of the risks and benefits associated with antibiotic use in food animals. We conclude that the use of antibiotics in food animal production constitutes a major contributing factor to the current antimicrobial resistance crisis and that antibiotics should only be used for the treatment of sick animals based on prior diagnosis of disease.

Drug Resistance and the Prevention Strategies in Food Borne Bacteria: An Update Review

Antibiotic therapy is among the most important treatments against infectious diseases and has tremendously improved effects on public health. Nowadays, development in using this treatment has led us to the emergence and enhancement of drug-resistant pathogens which can result in some problems including treatment failure, increased mortality as well as treatment costs, reduced infection control efficiency, and spread of resistant pathogens from hospital to community. Therefore, many researches have tried to find new alternative approaches to control and prevent this problem. This study, has been revealed some possible and effective approaches such as using farming practice, natural antibiotics, nano-antibiotics, lactic acid bacteria, bacteriocin, cyclopeptid, bacteriophage, synthetic biology and predatory bacteria as alternatives for traditional antibiotics to prevent or reduce the emergence of drug resistant bacteria.

Antimicrobial Susceptibility of Streptococci Most Frequently Isolated from Czech Dairy Cows with Mastitis

The aim was to investigate the antimicrobial susceptibility of most frequently isolated streptococci from Czech dairy herds. A total of 3,719 quarter milk samples were collected and cultivated between January 2017 and June 2018 from cows with clinical or subclinical mastitis from 112 farms. Only one isolate of each species, collected from the same farm per six-month period, was included in the susceptibility testing. The susceptibilities of Streptococcus uberis (163 isolates) and S. dysgalactiae (25 isolates) to 10 antimicrobials (penicillin – PEN, amoxicillin/clavulanic acid – AMC, ceftiofur – EFT, clindamycin – CLI, gentamicin – GEN, streptomycin – STR, trimethoprim/sulfamethoxazole – SXT, enrofloxacin – ENR, tetracycline – TET, rifampicin – RIF) from 9 groups were determined by measuring their minimum inhibitory concentrations. The percentages of resistant S. uberis isolates to the antimicrobials were as follows: TET (63.2%), STR (52.1%), CLI (30.1%), and RIF (2.5%). Intermediate susceptibility was found to RIF (63.2%), PEN (35%), ENR (2.5%), EFT (1.8%), and AMC (1.2%). All the S. uberis isolates were susceptible to GEN and SXT (100%). However, only 6.7% of S. uberis isolates were susceptible to all tested antimicrobials, and 38.7% of isolates were multidrug resistant (≥ 3 groups of antimicrobials). All the S. dysgalactiae isolates were susceptible to PEN, AMC, EFT, GEN, SXT, and ENR (100%). Resistant S. dysgalactiae isolates were found to TET (60%), STR (28%), CLI (12%), and intermediate to TET (24%) and RIF (20%). Sixteen percent of S. dysgalactiae isolates were multidrug resistant. The relatively high occurrence of (multiple) resistance, relative to mastitis pathogens, highlights the importance of monitoring this condition in dairy herds.

Monitoring Antibiotic Usage in German Dairy and Beef Cattle Farms-A Longitudinal Analysis

It is well-established that antimicrobial use is a major factor for the development of antimicrobial resistance. To analyze the associations between antimicrobial resistance and usage of antimicrobial agents, data from monitoring and surveillance systems are crucial. Within the project VetCAb (Veterinary Consumption of Antibiotics), antibiotic usage data in German livestock is regularly collected and evaluated. Based on a cross-sectional study in 2011, the project was continued as the longitudinal study VetCAb-Sentinel with ongoing participant recruitment and data collection from 2013. The data collection is based on official German application and delivery forms (ADF), voluntarily provided by veterinarians and farmers. In this study the results of antibiotic usage data of dairy cows, dairy calves and beef cattle were described, using a semi-annual treatment frequency, and 95,944 ADF issued between 2011 and 2015 were analyzed. Results show that the median of the treatment frequency in dairy calf and beef cattle holdings slightly decreased from 0.4 to 0.3 and from 0.2 to 0 days, respectively, whereas the median in dairy cow holdings ranged between 1.9 and 2.3 during the observed period. Temporal changes and the effect of the factors "farm size" and "region" on the treatment frequency were investigated, using multiple linear mixed and logistic regression models. Generally, the factor "time" has a statistically significant impact on the treatment frequency in all production types. In addition, a temporal trend test over the first six half-years shows that an increasing linear trend can be stated in dairy cows and dairy calves (p = 0.017; p = 0.004, respectively). If the time-period is extended to all eight half-years under study, this turns into a quadratic effect (dairy cows: p = 0.006; dairy calves: p < 0.001). In dairy calves and beef cattle the factor "farm size" also has a statistically significant impact. The factor "region," in contrast, shows no statistically significant impact at all. Compared to other livestock populations in Germany, the use of antimicrobials in dairy cows, dairy calves, and beef cattle appears to be low, but varies across several associated factors. Considering these effects, it is recommended that the size of dairy calf and beef cattle holdings is regularly considered in the evaluation of antimicrobial usage data over time.