Causal relationship between gut microbiota and prostate cancer contributes to the gut-prostate axis: insights from a Mendelian randomization study

BACKGROUND

Changes in gut microbiota abundance have been linked to prostate cancer development. However, the causality of the gut-prostate axis remains unclear.

METHODS

The genome-wide association study (GWAS) data for gut microbiota sourced from MiBioGen (n = 14,306), alongside prostate cancer summary data from PRACTICAL (n = 140,254) and FinnGen Consortium (n = 133,164). Inverse-variance-weighted (IVW) was mainly used to compute odds ratios (OR) and 95% confidence intervals (Cl), after diligently scrutinizing potential sources of heterogeneity and horizontal pleiotropy via the rigorous utilization of Cochran's Q test, the MR-PRESSO method, and MR-Egger. We used meta-analysis methods in random effects to combine the Mendelian randomization (MR) estimates from the two sources.

RESULTS

The pooled analyses of MR results show that genus Eubacterium fissicatena (OR = 1.07, 95% CI 1.01 to 1.13, P = 0.011) and genus Odoribacter (OR = 1.14, 95% CI 1.01 to 1.27, P = 0.025) were positively associated with prostate cancer. However, genus Adlercreutzia (OR = 0.89, 95% CI 0.83 to 0.96, P = 0.002), Roseburia (OR = 0.90, 95% CI 0.83 to 0.99, P = 0.03), Holdemania (OR = 0.92, 95% CI 0.86 to 0.97, P = 0.005), Flavonifractor (OR = 0.85, 95% CI 0.74 to 0.98, P = 0.024) and Allisonella (OR = 0.93, 95% CI 0.89 to 0.98, P = 0.011) seems to be a protective factor for prostate cancer. Sensitivity analysis found no significant heterogeneity, horizontal pleiotropy, or reverse causal links in all causal associations.

CONCLUSION

This MR study lends support to a causal relationship between genetically predicted gut microbiota and prostate cancer. Research on the gut-prostate axis, along with further multi-omics analyses, holds significant implications for the prevention and treatment of prostate cancer.

Evidence of Methicillin Resistant Staphylococcus Aureus (MRSA) in Pet and Stray Dogs Within Sokoto Metropolis, Nigeria

Methicillin Resistant Staphylococcus aureus (MRSA) is an important zoonotic pathogen capable of causing life threatening disease conditions in humans. A cross-sectional study was conducted to investigate the presence of MRSA in both pet and stray dogs within the Sokoto metropolis. A total of 100 oral swabs comprising 50 each from pet and stray dogs were collected and analyzed using routine bacteriological cultures and molecular identifications. Out of the 100 samples examined, 15 % (15/100) were positive for MRSA with varying detection rates of 9/50 (18 %) and 6/50 (12 %) for the pet and stray dogs respectively. The statistical analysis showed no significant association between the occurrence of MRSA and the dogs (P = 0.401). The study revealed the presence of MRSA in dogs within the Sokoto metropolis, which presents health risks to pet dog owners, veterinarians, dog catchers and other individuals who may come into close contact with these dogs.

Pilot Study on Alteration of LA-MRSA Status of Pigs during Fattening Period on Straw Bedding by Two Types of Cleaning

In countries with professional pig husbandry in stables, the prevalence of livestock-associated (LA) methicillin-resistant Staphylococcus aureus (MRSA) on farms has remained high or has further increased in recent years. Simple measures to reduce LA-MRSA among pigs have not yet been successfully implemented. The aim of this pilot study is twofold: first, to examine how the LA-MRSA status of LA-MRSA positive fattening pigs at the date of housing changes over the fatting period on straw bedding and, second, whether this change could be influenced by the quality of cleaning and disinfection (C&D). For this purpose, 122 animals are individually tested for LA-MRSA carriage at five sequential time points comparing pigs housed on a farm using straw bedding plus C&D (n = 59) vs. straw bedding plus simple cleaning (n = 63). At the time of housing, all animals in both groups are LA-MRSA positive. This status changes to 0% in the group with simple cleaning until the end of fattening and 28% in the C&D group. LA-MRSA in environmental and air samples is also reduced over the fattening period. The results indicate that keeping pigs on straw might be one way to reduce LA-MRSA during the fattening period with simple cleaning appearing to be more beneficial than C&D. Further investigations are necessary to determine the influencing factors more precisely.

Molecular survey of mcr1 and mcr2 plasmid mediated colistin resistance genes in Escherichia coli isolates of animal origin in Iran

Objectives

The emergence of colistin-resistant Enterobacteriaceae from human and animal sources is one of the major public health concerns as colistin is the last-resort antibiotic for treating infections caused by multidrug-resistant Gram-negative bacteria. We aimed to determine the prevalence of the prototype widespread colistin resistance genes (mcr-1 and mcr-2) among commensal and pathogenic Escherichia coli strains isolated from food-producing and companion animals in Iran.

Results

A total of 607 E. coli isolates which were previously collected from different animal sources between 2008 and 2016 used to uncover the possible presence of plasmid-mediated colistin resistance genes (mcr-1 and mcr-2) by PCR. Overall, our results could not confirm the presence of any mcr-1 or mcr-2 positive E. coli among the studied isolates. It is concluded that despite the important role of food-producing animals in transferring the antibiotic resistance, they were not the main source for carriage of mcr-1 and mcr-2 in Iran until 2016. This study suggests that the other mcr variants (mcr-3 to mcr-9) might be responsible for conferring colistin resistance in animal isolates in Iran. The possible linkage between pig farming industry and high level of mcr carriage in some countries needs to be clarified in future prospective studies.

Single Blinded Study on the Feasibility of Decontaminating LA-MRSA in Pig Compartments under Routine Conditions

： In countries with intensive pig husbandry in stables, the prevalence of livestock-associated (LA) methicillin-resistant Staphylococcus aureus (MRSA) on such farms has remained high in the last few years or has also further increased. Simple measures to reduce the LA-MRSA among pigs have not yet been successfully implemented. Earlier publications showed a decontamination of LA-MRSA was only possible with great effort. The aim of this study is to determine the suitability of routine cleaning and disinfection (C&D) for adequate LA-MRSA decontamination. For this purpose, at least 115 locations in a piglet-rearing compartment were examined before and after cleaning and disinfection. The sample locations were stratified according to accessibility for pigs and the difficulty of cleaning. The cleaning work was carried out routinely by farm employees, who were not informed about the sampling (single blinded). While before cleaning and disinfection, 85% of the samples from the surfaces were LA-MRSA positive, while only 2% were positive thereafter. All LA-MRSA-positive samples after cleaning and disinfection were outside the animal area. Air samples also showed no LA-MRSA after cleaning and disinfection. Conclusion: In well-managed livestock farms, decontamination of the LA-MRSA barn is quite possible; after C&D no LA-MRSA was detectable at animal height.

Extended-spectrum beta-lactamase (ESBL)-producing Enterobacteriaceae in cattle production - a threat around the world

Food producing animal is a global challenge in terms of antimicrobial resistance spread. Extended-spectrum beta-lactamase (ESBL)-producing Enterobacteriaceae are relevant opportunistic pathogens that may spread in many ecological niches of the One Health approach as human, animal and environment due to intestinal selection of antimicrobial resistant commensals in food production animals. Cattle production is a relevant ecological niche for selection of commensal bacteria with antimicrobial resistance from microbiota. Enterobacteriaceae show importance in terms of circulation of resistant-bacteria and antimicrobial resistance genes via food chain creating a resistance reservoir, setting up a threat for colonization of humans and consequent health risk. ESBL-producing Enterobacteriaceae are a threat in terms of human health responsible for life threatening outbreaks and silent enteric colonization of community populations namely the elder population. Food associated colonization is a risk difficult to handle and control. In a time of globalization of food trading, population intestinal colonization is a mirror of food production and in that sense this work aims to make a picture of ESBL-producing Enterobacteriaceae in animal production for food over the world in order to make some light in this reality of selection of resistant threats in food producing animal.

Regrowth of Microcosm Biofilms on Titanium Surfaces After Various Antimicrobial Treatments

Objectives: Our aim of this work was to investigate the regrowth of implant-related biofilms after various antimicrobial treatments in vitro. Methods: Saliva-derived microcosm biofilms were grown on titanium discs in an active attachment model. Treatments including hydrogen peroxide (HP), citric acid (CA), chlorhexidine (CHX), and distilled water (control), at different concentrations, were applied to 2-day biofilms for 1 or 5 min. The viability, lactic acid production, and composition of the biofilms were followed for 3 days. The biofilm composition was analyzed by 16S rDNA amplicon sequencing. Results: The short treatments of CA, CHX, and HP resulted in a 2-3 log reduction in biofilm viability and lactic acid production immediately. However, both parameters returned to the pre-treatment level within 2 days due to biofilm regrowth. The alpha diversity of the regrown biofilms in antimicrobial-treated groups tended to decrease, whereas the diversity of those in water-treated group increased. The composition of the regrown biofilms altered compared to those before treatments. Streptococcus and Enterobacteriaceae were enriched in the regrown biofilms. Conclusions: Although the antimicrobial treatments were efficient, the multi-species biofilms were indeed able to regrow within 2 days. The regrown biofilms display an altered microbial diversity and composition, which in the oral cavity may lead to an aggressive infection.

Routine antibiotic therapy in dogs increases the detection of antimicrobial-resistant faecal Escherichia coli

Background

Antimicrobial resistance (AMR) is a critical health problem, with systemic antimicrobial therapy driving development of AMR across the host spectrum.

Objectives

This study compares longitudinal carriage, at multiple timepoints, of AMR faecal Escherichia coli in dogs undergoing routine antimicrobial treatment.

Methods

Faecal samples (n = 457) from dogs (n = 127) were examined pretreatment, immediately after treatment and 1 month and 3 months post-treatment with one of five antimicrobials. Isolates were tested for susceptibility to a range of antimicrobials using disc diffusion for each treatment group at different timepoints; the presence/absence of corresponding resistance genes was investigated using PCR assays. The impact of treatment group/timepoint and other risk factors on the presence of resistance [MDR, fluoroquinolone resistance, third-generation cephalosporin resistance (3GCR) and ESBL and AmpC production] was investigated using multilevel modelling. Samples with at least one AMR E. coli from selective/non-selective agar were classed as positive. Resistance was also assessed at the isolate level, determining the abundance of AMR from non-selective culture.

Results

Treatment with β-lactams or fluoroquinolones was significantly associated with the detection of 3GCR, AmpC-producing, MDR and/or fluoroquinolone-resistant E. coli, but not ESBL-producing E. coli, immediately after treatment. However, 1 month post-treatment, only amoxicillin/clavulanate was significantly associated with the detection of 3GCR; there was no significant difference at 3 months post-treatment for any antimicrobial compared with pretreatment samples.

Conclusions

Our findings demonstrated that β-lactam and fluoroquinolone antibiotic usage is associated with increased detection of important phenotypic and genotypic AMR faecal E. coli following routine therapy in vet-visiting dogs. This has important implications for veterinary and public health in terms of antimicrobial prescribing and biosecurity protocols, and dog waste disposal.

The human gastrointestinal microbiota and prostate cancer development and treatment

The human gastrointestinal microbiome contains commensal bacteria and other microbiota that have been gaining increasing attention in the context of cancer development and response to treatment. Microbiota play a role in the maintenance of host barrier surfaces that contribute to both local inflammation and other systemic metabolic functions. In the context of prostate cancer, the gastrointestinal microbiome may play a role through metabolism of estrogen, an increase of which has been linked to the induction of prostatic neoplasia. Specific microbiota such as Bacteroides, Streptococcus, Bacteroides massiliensis, Faecalibacterium prausnitzii, Eubacterium rectalie, and Mycoplasma genitalium have been associated with differing risks of prostate cancer development or extensiveness of prostate cancer disease. In this Review, we discuss gastrointestinal microbiota's effects on prostate cancer development, the ability of the microbiome to regulate chemotherapy for prostate cancer treatment, and the importance of using Next Generation Sequencing to further discern the microbiome's systemic influence on prostate cancer.

Extended-spectrum beta-lactamase and ampicillin Class C beta lactamase-producing Escherichia coli from food animals: A review

Antimicrobial resistance has gained global notoriety due to its public health concern, the emergence of multiple drug-resistant bacteria, and lack of new antimicrobials. Extended-spectrum beta-lactamase (ESBL)/ampicillin Class C (AmpC)- producing Escherichia coli and other zoonotic pathogens can be transmitted to humans from animals either through the food chain, direct contact or contamination of shared environments. There is a surge in the rate of resistance to medically important antibiotics such as carbapenem, ESBL, aminoglycosides, and fluoroquinolones among bacteria of zoonotic importance. Factors that may facilitate the occurrence, persistence and dissemination of ESBL/AmpC-Producing E. coli in humans and animal includes; 1). o ral administration of antimicrobials to humans primarily (by physician and health care providers) and secondarily to animals, 2). importation of parent stock and day-old chickens, 3). farm management practice and lack of water acidification in poultry, 4). contamination of feed, water and environment, 5). contamination of plants with feces of animals. Understanding these key factors will help reduce the level of resistance, thereby boosting the therapeutic effectiveness of antimicrobial agents in the treatment of animal and human infections. This review highlights the occurrence, risk factors, and public health importance of ESBL/AmpC-beta-lactamase producing E. coli isolated from livestock.

Wound Healing Activity of Plants from the Convolvulaceae Family

Significance: Compounds derived from plants are gaining importance for the treatment of several diseases. Many plants from the Convolvulaceae family contain compounds that have demonstrated wound healing and antidiabetic activity. Such compounds can be effectively used as a part of treatments to promote wound healing in diabetics and used in combination with antimicrobial therapy to reduce the likelihood of drug resistance and allergic reactions. Novel strategies for developing herbal formulations such as nanoparticles and adhesive patches can improve the delivery of plant-based therapeutic agents. Recent Advances: Studies have confirmed the antidiabetic and wound healing activities of Merremia tridentata, Argyreia speciosa, and Ipomoea batatas, whereas Evolvulus alsinoides, Evolvulus nummularius, Argyreia cuneata, and Ipomoea carnea have wound healing activity. Critical Issues: Drug resistance is a major problem associated with antimicrobial therapy and can affect wound healing processes. Phytoconstituents can facilitate healing processes and reduce reliance on antibiotics. Future Directions: Plants from the Convolvulaceae family have had frequent traditional uses, and all plants selected for this study have antimicrobial, antidiabetic, and wound healing properties. Detailed phytochemical studies of these plants can help develop novel wound healing therapies.

Reservoirs and Transmission Pathways of Resistant Indicator Bacteria in the Biotope Pig Stable and along the Food Chain: A Review from a One Health Perspective

The holistic approach of “One Health” includes the consideration of possible links between animals, humans, and the environment. In this review, an effort was made to highlight knowledge gaps and various factors that contribute to the transmission of antibiotic-resistant bacteria between these three reservoirs. Due to the broad scope of this topic, we focused on pig production and selected “indicator bacteria”. In this context, the role of the bacteria livestock-associated methicillin-resistant Staphylococcus aureus (LA-MRSA) and extended spectrum beta-lactamases carrying Escherichia coli (ESBL-E) along the pig production was particularly addressed. Hotspots of their prevalence and transmission are, for example, pig stable air for MRSA, or wastewater and manure for ESBL-E, or even humans as vectors in close contact to pigs (farmers and veterinarians). Thus, this review focuses on the biotope “stable environment” where humans and animals are both affected, but also where the end of the food chain is not neglected. We provide basic background information about antibiotics in livestock, MRSA, and ESBL-bacteria. We further present studies (predominantly European studies) in tabular form regarding the risk potentials for the transmission of resistant bacteria for humans, animals, and meat differentiated according to biotopes. However, we cannot guarantee completeness as this was only intended to give a broad superficial overview. We point out sustainable biotope approaches to try to contribute to policy management as critical assessment points in pig housing conditions, environmental care, animal health, and food product safety and quality as well as consumer acceptance have already been defined.

Detection and Characterization of Extended-Spectrum Beta-Lactamases-Producing Escherichia coli in Animals

The detection of multidrug-resistant bacteria is a growing problem; however, the role of domesticated animals in the propagation of antimicrobial resistance has barely been studied. The aim of this study was to identify extended-spectrum beta-lactamase (ESBL)-producing Escherichia coli strains in domestic animal feces to assess their antimicrobial resistance profile and carry out molecular characterization of the β-lactamases. A total of 325 samples were collected from eight animal species. Of these, 34 bacterial isolates were identified as E. coli. The antibiotic resistance profile of the E. coli strains was as follows: 100% resistant to amoxicillin, aztreonam, and cephalosporins; 58.8% resistant to nalidixic acid, ciprofloxacin, and trimethoprim/sulfamethoxazole; 41.2% resistant to gentamicin and tobramycin; 11.8% resistant and 32.4% intermediate to cefoxitin; 97.1% sensible and 2.9% intermediate to amoxicillin/clavulanate; and 100% sensible to ertapenem, minocycline, imipenem, meropenem, amikacin, nitrofurantoin, fosfomycin, and colistin. All 34 E. coli strains met criteria for ESBL production. In total, 46 β-lactamase genes were detected: 43.5% bla_TEM, 30.4% bla_CTX-M (23.9% bla_CTX-M-1 and 6.5% bla_CTX-M-9), and 26.1% bla_SHV (17.4% bla_SHV-5 and 8.7% bla_SHV-12). All the β-lactamases were found in dogs except for four bla_SHV found in falcons. No plasmidic AmpC genes were found. The high prevalence of ESBL-producing E. coli strains in animals could become a zoonotic transmission vector.

Antimicrobial use and antimicrobial resistance in food animals

Antimicrobials have been widely used in food animals for growth promotion since the 1950s. Antimicrobial resistance emerges in animal production settings and frequently spreads to humans through the food chain and direct contact. There have been international efforts to restrict or ban antimicrobials used for both humans and animals. Denmark has taken positive strides in the development of a comprehensive database DANMAP to track antimicrobial usage and resistance. Although food animals are sources of antimicrobial resistance, there is little evidence that antimicrobial resistance originates from food animals. This review comprehensively introduces the history and trends of antimicrobial use, the emergence and spread of antimicrobial resistance in food animals provides suggestions to tackle the problems of the spread of antimicrobial resistance.

Prevalence and Characterization of β-Lactamases Genes and Class 1 Integrons in Multidrug-Resistant Escherichia coli Isolates from Chicken Meat in Korea

Antimicrobial resistance has become a serious public health threat throughout the world, and therapeutic options for several infectious diseases are currently limited by the presence of multidrug-resistant (MDR) bacteria. This study was designed to examine the drug resistance patterns, the prevalence of the β-lactamases, and class 1 integrons in MDR Escherichia coli isolates from chicken meat in Korea. Among 200 chicken meat samples, 101 isolates were observed to be positive for E. coli, of which 57 were identified as MDR E. coli. Among 57 MDR E. coli isolates, the prevalence of bla gene, bla_CTX-M-1, bla_CTX-M-14, and bla_TEM-1, were identified in 2, 4, and 16 E. coli strains, respectively; only 1 E. coli strain had both, bla_TEM-1 and bla_CTX-M-1 genes. Twenty-one of the 57 MDR E. coli isolates also carried class 1 integrons, and 5 different gene cassette arrangements were found in 14 of the 21 class 1 integron-positive isolates. The β-lactamase-producing E. coli and integron-positive E. coli had significantly higher resistance to 16 antimicrobial drugs than the non-β-lactamase-producing E. coli and the integron-negative E. coli (p < 0.05). Our findings suggest that β-lactamase and class 1 integrons are widely distributed in E. coli isolates from chicken meat, and directly contribute to resistance to diverse antimicrobial agents. Therefore, continuous investigation of integron gene cassette arrays will provide useful information regarding antimicrobial resistance mechanisms.

Fluoroquinolone Restriction as an Effective Antimicrobial Stewardship Intervention

PURPOSE OF REVIEW

Fluoroquinolones are a commonly prescribed antibiotic class that has come under scrutiny in recent years due to mounting evidence of association between adverse drug events, C. difficile infection and isolation of antibiotic-resistant bacteria.

RECENT FINDINGS

Inpatient antimicrobial stewardship (AMS) programs have a toolbox of potential interventions to curb inappropriate antibiotic use, prevent antibiotic-associated adverse drug events, and avoid unnecessary costs of care. Fluoroquinolone restriction policies in the acute care setting have demonstrated beneficial effects, including decreased rates of C. difficile infection and ESBL-producing Enterobacteriaceae. However, a simple blanket restriction policy may "squeeze the antibiotic balloon" and will likely be insufficient if not implemented in conjunction with other AMS interventions. There is a growing body of evidence to support formulary restriction of fluoroquinolones in the acute care setting to decrease rates of C. difficile infection and development of ESBL-producing organisms. Data on how to best implement these restrictions or how to implement outside of acute care settings is limited.

Global epidemiology of CTX-M β-lactamases: temporal and geographical shifts in genotype

Globally, rates of ESBL-producing Enterobacteriaceae are rising. We undertook a literature review, and present the temporal trends in blaCTX-M epidemiology, showing that blaCTX-M-15 and blaCTX-M-14 have displaced other genotypes in many parts of the world. Explanations for these changes can be attributed to: (i) horizontal gene transfer (HGT) of plasmids; (ii) successful Escherichia coli clones; (iii) ESBLs in food animals; (iv) the natural environment; and (v) human migration and access to basic sanitation. We also provide explanations for the changing epidemiology of blaCTX-M-2 and blaCTX-M-27. Modifiable anthropogenic factors, such as poor access to basic sanitary facilities, encourage the spread of blaCTX-M and other antimicrobial resistance (AMR) genes, such as blaNDM, blaKPC and mcr-1. We provide further justification for novel preventative and interventional strategies to reduce transmission of these AMR genes.

A Novel Methicillin-Resistant Staphylococcus aureus t11469 and a Poultry Endemic Strain t002 (ST5) Are Present in Chicken in Ebonyi State, Nigeria

Background

The changing epidemiology of methicillin-resistant Staphylococcus aureus (MRSA) from a hospital-associated pathogen to an organism commonly found in the community and in livestock reflects an organism well-equipped to survive in diverse environments and adjust to different environmental conditions including antimicrobial use.

Methods

We investigated the molecular epidemiology of S. aureus and MRSA in poultry in Ebonyi State, Nigeria. Samples were collected from 1800 birds on 9 different farms within the state. Positive isolates were tested for antibiotic susceptibility and molecular typing.

Results

Prevalence in birds was 13.7% (247/1800). MRSA prevalence in poultry was 0.8%. The prevalence of MRSA in broilers and layers was 1.2% and 0.4%, respectively. All tested isolates were susceptible to vancomycin. Molecular analysis of the isolates revealed 3 spa types: t002, t084, and a novel spa type, t11469. The novel spa type t11469 belonged to sequence type ST5.

Conclusion

The detection of t002 in chicken suggests the presence of livestock-associated MRSA in poultry in Ebonyi State. The detection of the new spa type t11469 in poultry that has not been characterised to ascertain its pathogenic potential remains a cause for concern, especially as some were found to carry PVL genes, a putative virulence factor in staphylococcal infection.

Carriage frequency, phenotypic, and genotypic characteristics of methicillin-resistant Staphylococcus aureus isolated from dental health-care personnel, patients, and environment

There is limited data on methicillin-resistant Staphylococcus aureus (MRSA) carriage in dental clinics. 1300 specimens from patients, health personnel, and environmental surfaces of a dental clinic in Egypt were tested for MRSA. Antibiotic susceptibility, biofilm formation, Staphylococcal protein A (spa) typing, SCCmec typing, and PCR-based assays were used to detect mecA, mecC, vanA, Panton-Valentine Leukocidin toxin (PVL), and toxic shock syndrome toxin-1 (tst) genes. Among 34 mecA-positive MRSA isolates, five (14.7%) were PVL-positive, seventeen (50%) were tst-positive, ten (29.4%) were vanA-positive, while none harboured mecC. MRSA hand carriage rates in patients, nurses, and dentists were 9.8%, 6.6%, and 5%. The respective nasal colonization rates were 11.1%, 6.7%, and 9.7%. 1.3% of the environmental isolates were MRSA-positive. Strong and moderate biofilm-forming isolates represented 23.5% and 29.4% of MRSA isolates. 24 MRSA isolates (70.6%) were multi-resistant and 18 (52.9%) harboured SCCmec IV. Among eight spa types, t223 (26.5%), t267 (23.5%), and t14339 (23.5%) were predominant. We noted an alarming genetic relatedness between 7 (20.6%) MRSA isolates and the epidemic EMRSA-15 clone, as well as a combined occurrence of tst and PVL in 3 (8.8%) isolates. Results suggest high MRSA pathogenicity in dental wards highlighting the need for more efficient surveillance/infection control strategies.

Bacteria from Animals as a Pool of Antimicrobial Resistance Genes

Antimicrobial agents are used in both veterinary and human medicine. The intensive use of antimicrobials in animals may promote the fixation of antimicrobial resistance genes in bacteria, which may be zoonotic or capable to transfer these genes to human-adapted pathogens or to human gut microbiota via direct contact, food or the environment. This review summarizes the current knowledge of the use of antimicrobial agents in animal health and explores the role of bacteria from animals as a pool of antimicrobial resistance genes for human bacteria. This review focused in relevant examples within the ESC(K)APE (Enterococcus faecium, Staphylococcus aureus, Clostridium difficile (Klebsiella pneumoniae), Acinetobacter baumannii, Pseudomonas aeruginosa, and Enterobacteriaceae) group of bacterial pathogens that are the leading cause of nosocomial infections throughout the world.

vanA Gene Harboring Enterococcal and Non-enterococcal Isolates Expressing High Level Vancomycin and Teicoplanin Resistance Reservoired in Surface Waters

Untreated wastewaters and treated effluents even after final disinfection contain antibiotic resistant bacteria and resistance genes before they are released into surface waters. A correlation between resistant bacteria and antibiotics in surface waters has been found, as have antibiotic resistance genes. Of particular interest are vancomycin-resistant enterococci harboring vanA gene that confers high level of resistance to glycopeptide antibiotics including teicoplanin. Therefore, in this study, river water samples were analysed to investigate vancomycin- and teicoplanin-resistant bacterial isolates harboring vanA gene. Out of 290, 15 surface water isolates displayed resistance to both antibiotics. These glycopeptide resistant enterococcal and non-enterococcal isolates, identified by 16S rRNA sequencing, were found to harbor vanA gene with sequence similarities of 50 % to 100 %. The presence of D-alanine-D-lactate ligase encoded by vanA gene was also shown for all vancomycin- and teicoplanin-resistant isolates through western blot analysis. Due to reuse of treated wastewater and release of untreated wastewaters to water bodies, antibiotic resistant bacteria and resistance genes are being introduced into surface waters and present human health risks. Therefore, surface waters are not only hot spots for vanA harboring enterococcal isolates but also non-enterococcal isolates due to gene dissemination and require special scientific consideration.

The Host Microbiome Regulates and Maintains Human Health: A Primer and Perspective for Non-Microbiologists

Humans consider themselves discrete autonomous organisms, but recent research is rapidly strengthening the appreciation that associated microorganisms make essential contributions to human health and well being. Each person is inhabited and also surrounded by his/her own signature microbial cloud. A low diversity of microorganisms is associated with a plethora of diseases, including allergy, diabetes, obesity, arthritis, inflammatory bowel diseases, and even neuropsychiatric disorders. Thus, an interaction of microorganisms with the host immune system is required for a healthy body. Exposure to microorganisms from the moment we are born and appropriate microbiome assembly during childhood are essential for establishing an active immune system necessary to prevent disease later in life. Exposure to microorganisms educates the immune system, induces adaptive immunity, and initiates memory B and T cells that are essential to combat various pathogens. The correct microbial-based education of immune cells may be critical in preventing the development of autoimmune diseases and cancer. This review provides a broad overview of the importance of the host microbiome and accumulating knowledge of how it regulates and maintains a healthy human system. Cancer Res; 77(8); 1783-812. ©2017 AACR.

Impact of a United Kingdom-wide campaign to tackle antimicrobial resistance on self-reported knowledge and behaviour change

BACKGROUND

As part of the 2014 European Antibiotic Awareness Day plans, a new campaign called Antibiotic Guardian (AG) was launched in the United Kingdom, including an online pledge system to increase commitment from healthcare professionals and members of the public to reduce antimicrobial resistance (AMR). The aim of this evaluation was to determine the impact of the campaign on self-reported knowledge and behaviour around AMR.

METHODS

An online survey was sent to 9016 Antibiotic Guardians (AGs) to assess changes in self-reported knowledge and behaviour (outcomes) following the campaign. Logistic regression models, adjusted for variables including age, sex and pledge group (pledging as member of public or as healthcare professional), were used to estimate associations between outcomes and AG characteristics.

RESULTS

2478 AGs responded to the survey (27.5 % response rate) of whom 1696 (68.4 %) pledged as healthcare professionals and 782 (31.6 %) as members of public (similar proportions to the total number of AGs). 96.3 % of all AGs who responded had prior knowledge of AMR. 73.5 % of participants were female and participants were most commonly between 45 and 54 years old. Two thirds (63.4 %) of participants reported always acting according to their pledge. Members of the public were more likely to act in line with their pledge than professionals (Odds Ratio (OR) =3.60, 95 % Confidence Interval (CI): 2.88-4.51). Approximately half of participants (44.5 %) (both healthcare professionals and members of public) reported that they acquired more knowledge about AMR post-campaign. People that were confused about AMR prior to the campaign acquired more knowledge after the campaign (OR = 3.10, 95 % CI: 1.36-7.09). More participants reported a sense of personal responsibility towards tackling AMR post-campaign, increasing from 58.3 % of participants pre-campaign to 70.5 % post-campaign.

CONCLUSION

This study demonstrated that the campaign increased commitment to tackling AMR in both healthcare professional and member of the public, increased self-reported knowledge and changed self-reported behaviour particularly among people with prior AMR awareness. Online pledge schemes can be an effective and inexpensive way to engage people with the problem of AMR especially among those with prior awareness of the topic.

A review of the effects of dietary organic acids fed to swine

Animal production depends on nutrient utilization and if done there is an accelerated momentum towards growth with a low cost to feed ratio Public concern over the consumption of pork with antibiotic residues of the animals fed with antibiotic growth promoters (AGP) has paved the way to use other additives like herbs and their products, probiotics, prebiotics etc. Numerous feed additives are in vogue for achieving this target and one such classical example is the usage of organic acids and their salts. Usage of organic acids was in progress for over four decades. Early weaned piglets are (3–4 weeks age) exposed to stress with a reduced feed intake, little or no weight gain. This post weaning lag period is due to a limited digestive and absorptive capacity due to insufficient production of hydrochloric acid, pancreatic enzymes and sudden changes in feed consistency and intake. Lowering dietary pH by weak organic acids was found to overcome these problems. The main activity of organic acids is associated with a reduction in gastric pH converting the inactive pepsinogen to active pepsin for effective protein hydrolysis. Organic acids are both bacteriostatic and bactericidal. Lactic acid has been reported to reduce gastric pH and delay the multiplication of an enterotoxigenic E. coli. These acids are the intermediary products in Kreb’s cycle and thus act as an energy source preventing the tissue breakdown resulting from gluconeogenesis and lipolysis. Excretion of supplemental minerals and nitrogen are minimized with organic acids as these form complexes with minerals and aids for their bio-availability. Short chain fatty cids like acetic, propionic and n-butyric acid produced by microbial fermentation of dietary fibre in the large intestines may increase the proliferation of epithelial cells and have stimulatory effects on both endocrine and exocrine pancreatic secretions in pigs. Organic acids also enhances apparent total tract digestibility and improves growth performance. It is concluded that organic acids and their salts increase the protein utilization especially in weaner pigs and improves production indices.

Eradication of methicillin-resistant Staphylococcus aureus and of Enterobacteriaceae expressing extended-spectrum beta-lactamases on a model pig farm

Colonization of livestock with bacteria resistant to antibiotics is considered a risk for the entry of drug-resistant pathogens into the food chain. For this reason, there is a need for novel concepts to address the eradication of drug-resistant commensals on farms. In the present report, we evaluated the decontamination measures taken on a farm contaminated with methicillin-resistant Staphylococcus aureus (MRSA) and Enterobacteriaceae expressing extended-spectrum β-lactamases (ESBL-E). The decontamination process preceded the conversion from piglet breeding to gilt production. Microbiological surveillance showed that the decontamination measures eliminated the MRSA and ESBL-E strains that were detected on the farm before the complete removal of pigs, cleaning and disinfection of the stable, and construction of an additional stable meeting high-quality standards. After pig production was restarted, ESBL-E remained undetectable over 12 months, but MRSA was recovered from pigs and the environment within the first 2 days. However, spa (Staphylococcus aureus protein A gene) typing revealed acquisition of an MRSA strain (type t034) that had not been detected before decontamination. Interestingly, we observed that a farmworker who had been colonized with the prior MRSA strain (t2011) acquired the new strain (t034) after 2 months. In summary, this report demonstrates that decontamination protocols similar to those used here can lead to successful elimination of contaminating MRSA and ESBL-E in pigs and the stable environment. Nevertheless, decontamination protocols do not prevent the acquisition of new MRSA strains.

Antimicrobial Resistance, Extended-Spectrum β-Lactamase Productivity, and Class 1 Integrons in Escherichia coli from Healthy Swine

Administration of antimicrobials to food-producing animals increases the risk of higher antimicrobial resistance in the normal intestinal flora of these animals. The present cross-sectional study was conducted to investigate antimicrobial susceptibility and extended-spectrum β-lactamase (ESBL)-producing strains and to characterize class 1 integrons in Escherichia coli in healthy swine in Thailand. All 122 of the tested isolates had drug-resistant phenotypes. High resistance was found to ampicillin (98.4% of isolates), chloramphenicol (95.9%), gentamicin (78.7%), streptomycin (77.9%), tetracycline (74.6%), and cefotaxime (72.1%). Fifty-four (44.3%) of the E. coli isolates were confirmed as ESBL-producing strains. Among them, blaCTX-M (45 isolates) and blaTEM (41 isolates) were detected. Of the blaCTX-M-positive E. coli isolates, 37 carried the blaCTX-M-1 cluster, 12 carried the blaCTX-M-9 cluster, and 5 carried both clusters. Sequence analysis revealed blaTEM-1, blaTEM-135, and blaTEM-175 in 38, 2, and 1 isolate, respectively. Eighty-seven (71%) of the 122isolates carried class 1 integrons, and eight distinct drug-resistance gene cassettes with seven different integron profiles were identified in 43 of these isolates. Gene cassettes were associated with resistance to aminoglycosides (aadA1, aadA2, aadA22, or aadA23), trimethoprim (dfrA5, dfrA12, or dfrA17), and lincosamide (linF). Genes encoding β-lactamases were not found in class 1 integrons. This study is the first to report ESBL-producing E. coli with a class 1 integron carrying the linF gene cassette in swine in Thailand. Our findings confirm that swine can be a reservoir of ESBL-producing E. coli harboring class 1 integrons, which may become a potential health risk if these integrons are transmitted to humans. Intensive analyses of animal, human, and environmental isolates are needed to control the spread of ESBL-producing E. coli strains.

Agriculture and food animals as a source of antimicrobial-resistant bacteria

One of the major breakthroughs in the history of medicine is undoubtedly the discovery of antibiotics. Their use in animal husbandry and veterinary medicine has resulted in healthier and more productive farm animals, ensuring the welfare and health of both animals and humans. Unfortunately, from the first use of penicillin, the resistance countdown started to tick. Nowadays, the infections caused by antibiotic-resistant bacteria are increasing, and resistance to antibiotics is probably the major public health problem. Antibiotic use in farm animals has been criticized for contributing to the emergence of resistance. The use and misuse of antibiotics in farm animal settings as growth promoters or as nonspecific means of infection prevention and treatment has boosted antibiotic consumption and resistance among bacteria in the animal habitat. This reservoir of resistance can be transmitted directly or indirectly to humans through food consumption and direct or indirect contact. Resistant bacteria can cause serious health effects directly or via the transmission of the antibiotic resistance traits to pathogens, causing illnesses that are difficult to treat and that therefore have higher morbidity and mortality rates. In addition, the selection and proliferation of antibiotic-resistant strains can be disseminated to the environment via animal waste, enhancing the resistance reservoir that exists in the environmental microbiome. In this review, an effort is made to highlight the various factors that contribute to the emergence of antibiotic resistance in farm animals and to provide some insights into possible solutions to this major health issue.

Biosensors, antibiotics and food

Antibiotics are medicine's leading asset for fighting microbial infection, which is one of the leading causes of death worldwide. However, the misuse of antibiotics has led to the rapid spread of antibiotic resistance among bacteria and the development of multiple resistant pathogens. Therefore, antibiotics are rapidly losing their antimicrobial value. The use of antibiotics in food production animals is strictly controlled by the European Union (EU). Veterinary use is regulated to prevent the spread of resistance. EU legislation establishes maximum residue limits for veterinary medicinal products in foodstuffs of animal origin and enforces the establishment and execution of national monitoring plans. Among samples selected for monitoring, suspected noncompliant samples are screened and then subjected to confirmatory analysis to establish the identity and concentration of the contaminant. Screening methods for antibiotic residues are typically based on microbiological growth inhibition, whereas physico-chemical methods are used for confirmatory analysis. This chapter discusses biosensors, especially whole-cell based biosensors, as emerging screening methods for antibiotic residues. Whole-cell biosensors can offer highly sensitive and specific detection of residues. Applications demonstrating quantitative analysis and specific analyte identification further improve their potential as screening methods.

Inappropriate use of antibiotics in hospitals: the complex relationship between antibiotic use and antimicrobial resistance

Hospitals are considered an excellent compartment for the selection of resistant and multi-drug resistant (MDR) bacteria. The overuse and misuse of antimicrobial agents are considered key points fuelling this situation. Antimicrobial stewardship programs have been designed for better use of these compounds to prevent the emergence of resistant microorganisms and to diminish the upward trend in resistance. Nevertheless, the relationship between antibiotic use and antimicrobial resistance is complex, and the desired objectives are difficult to reach. Various factors affecting this relationship have been advocated including, among others, antibiotic exposure and mutant selection windows, antimicrobial pharmacodynamics, the nature of the resistance (natural or acquired, including mutational and that associated with horizontal gene transfer) and the definition of resistance. Moreover, antimicrobial policies to promote better use of these drugs should be implemented not only in the hospital setting coupled with infection control programs, but also in the community, which should also include animal and environmental compartments. Within hospitals, the restriction of antimicrobials, cycling and mixing strategies and the use of combination therapies have been used to avoid resistance. Nevertheless, the results have not always been favorable and resistant bacteria have persisted despite the theoretical benefits of these strategies. Mathematical models as well as microbiological knowledge can explain this failure, which is mainly related to the current scenario involving MDR bacteria and overcoming the fitness associated with resistance. New antimicrobials, rapid diagnostic and antimicrobial susceptibility testing and biomarkers will be useful for future antimicrobial stewardship interventions.

Antibiotic resistance gene discovery in food-producing animals

Numerous environmental reservoirs contribute to the widespread antibiotic resistance problem in human pathogens. One environmental reservoir of particular importance is the intestinal bacteria of food-producing animals. In this review I examine recent discoveries of antibiotic resistance genes in agricultural animals. Two types of antibiotic resistance gene discoveries will be discussed: the use of classic microbiological and molecular techniques, such as culturing and PCR, to identify known genes not previously reported in animals; and the application of high-throughput technologies, such as metagenomics, to identify novel genes and gene transfer mechanisms. These discoveries confirm that antibiotics should be limited to prudent uses.

The pqqC gene is essential for antifungal activity of Pseudomonas kilonensis JX22 against Fusarium oxysporum f. sp. lycopersici

Strain JX22, exhibiting a broad range of antimicrobial activities to fungal pathogens, was isolated and classified as representing Pseudomonas kilonensis. In this study, the mutant JX22MT1 was obtained by the EZ-Tn5 transposon mutation and showed no antifungal activity against Fusarium oxysporum f. sp. lycopersici as compared with wild-type strain JX22. The pqqC gene was disrupted in the mutant. Antifungal activity at the wild-type level was restored from the mutant JX22MT1 with the introduction of the functional pqqC gene, which encodes pyrroloquinoline-quinone synthesis protein C. The results suggest that pqqC is essential for antifungal activity of P. kilonensis JX22 against F. oxysporum f. sp. lycopersici.

Efficacy of 5-day parenteral versus intramammary benzylpenicillin for treatment of clinical mastitis caused by gram-positive bacteria susceptible to penicillin in vitro

The efficacy of parenteral (intramuscular) or intramammary (IMM) benzylpenicillin treatment for clinical mastitis caused by gram-positive bacteria susceptible to penicillin in vitro was investigated. Cows with clinical mastitis in 1 udder quarter were randomly placed into 2 treatment groups. The preliminary bacteriological diagnosis of intramammary infection (IMI) was based on on-farm culturing, and the bacteriological diagnoses were later confirmed by a quantitative PCR assay. Clinical mastitis caused by gram-positive bacteria susceptible to benzylpenicillin was treated with penicillin via either the parenteral route (20mg/kg) or IMM route (600mg) once per day for 5d. The outcome of the treatment was evaluated 3 to 4wk after the onset of the treatment. The affected quarter was examined to assess the clinical cure, and milk samples were collected from the affected quarter to determine the bacteriological cure and milk N-acetyl-β-d-glucosaminidase activity. The survival and the composite milk somatic cell counts of the treated cows were followed up for 6 and 3mo after treatment, respectively. A total of 140 cows with clinical mastitis were included in the study, 61 being treated with benzylpenicillin parenterally and 79 via the IMM route. From all quarters treated, 108 of 140 (77.1%) were cured clinically and 77 of 140 (55.0%) were cured bacteriologically. The route of treatment did not significantly affect the outcome of the treatment; 80.3% of the quarters with parenteral treatment and 74.7% of the quarters with IMM treatment showed a clinical cure, and 54.1 and 55.7% a bacteriological cure, respectively. The milk N-acetyl-β-d-glucosaminidase activity was significantly lower in the quarters with a clinical or bacteriological cure than in the quarters with no cure. The 6-mo survival and the proportion of cows with composite milk somatic cell counts <200,000/mL among the treated cows during the 3-mo follow-up period did not significantly differ between the treatment groups. In conclusion, the outcome of either parenteral or IMM benzylpenicillin treatment of clinical mastitis caused by penicillin-susceptible bacteria was similar.

Comparison of broad-spectrum cephalosporin-resistant Escherichia coli isolated from dogs and humans in Hokkaido, Japan

Resistance to broad-spectrum cephalosporins (BSCs) in Enterobacteriaceae in companion animals has become a great concern for public health. To estimate the dissemination of BSC-resistant bacteria between dog and human, we examined the BSC-resistance determinants of and genetic similarities between 69 BSC-resistant Escherichia coli isolates derived from canine rectal swabs (n = 28) and human clinical samples (n = 41). Some E. coli isolates possessed blaTEM-1b (14 canine and 16 human isolates), blaCTx-M-2 (6 human isolates), blaCTx-M-14 (3 canine and 14 human isolates), blaCTx-M-27 (1 canine and 15 human isolates), and blaCMY-2 (11 canine and 3 human isolates). The possession of CTX-M-type β-lactamases was significantly more frequent in human isolates, whereas CMY-2 was more common in canine isolates. Bacterial typing methods (phylogenetic typing, O-antigen serotyping, and pulsed-field gel electrophoresis) showed little clonal relationship between canine isolates and human isolates. Plasmid analysis and Southern blotting indicated that the plasmids encoding CMY-2 were similar among canine and human isolates. Based on the differences in the major β-lactamase and the divergence of bacterial types between canine and human isolates, it seems that clonal dissemination of BSC-resistant E. coli between canines and humans is limited. The similarity of the CMY-2-encoding plasmid suggests that plasmid-mediated β-lactamase gene transmission plays a role in interspecies diffusion of BSC-resistant E. coli between dog and human.

Detection and molecular characterization of Escherichia coli CTX-M-15 and Klebsiella pneumoniae SHV-12 β-lactamases from bovine mastitis isolates in the United Kingdom

Recent reports raised concerns about the role that farm stock may play in the dissemination of extended-spectrum β-lactamase (ESBL)-producing bacteria. This study characterized the ESBLs in two Escherichia coli and three Klebsiella pneumoniae subsp. pneumoniae isolates from cases of clinical bovine mastitis in the United Kingdom. Bacterial culture and sensitivity testing of bovine mastitic milk samples identified Gram-negative cefpodoxime-resistant isolates, which were assessed for their ESBL phenotypes. Conjugation experiments and PCR-based replicon typing (PBRT) were used for characterization of transferable plasmids. E. coli isolates belonged to sequence type 88 (ST88; determined by multilocus sequence typing) and carried blaCTX-M-15 and blaTEM-1, while K. pneumoniae subsp. pneumoniae isolates carried blaSHV-12 and blaTEM-1. Conjugation experiments demonstrated that blaCTX-M-15 and blaTEM-1 were carried on a conjugative plasmid in E. coli, and PBRT identified this to be an IncI1 plasmid. The resistance genes were nontransferable in K. pneumoniae subsp. pneumoniae isolates. Moreover, in the E. coli isolates, an association of ISEcp1 and IS26 with blaCTX-M-15 was found where the IS26 element was inserted upstream of both ISEcp1 and the blaCTX-M promoter, a genetic arrangement highly similar to that described in some United Kingdom human isolates. We report the first cases in Europe of bovine mastitis due to E. coli CTX-M-15 and also of bovine mastitis due to K. pneumoniae subsp. pneumoniae SHV-12 β-lactamases in the United Kingdom. We also describe the genetic environment of blaCTX-M-15 and highlight the role that IncI1 plasmids may play in the spread and dissemination of ESBL genes, which have been described in both human and cattle isolates.

Comparative analysis of ESBL-positive Escherichia coli isolates from animals and humans from the UK, The Netherlands and Germany

The putative virulence and antimicrobial resistance gene contents of extended spectrum β-lactamase (ESBL)-positive E. coli (n=629) isolated between 2005 and 2009 from humans, animals and animal food products in Germany, The Netherlands and the UK were compared using a microarray approach to test the suitability of this approach with regard to determining their similarities. A selection of isolates (n=313) were also analysed by multilocus sequence typing (MLST). Isolates harbouring bla_{CTX-M-group-1} dominated (66%, n=418) and originated from both animals and cases of human infections in all three countries; 23% (n=144) of all isolates contained both bla_{CTX-M-group-1} and bla_OXA-1-like genes, predominantly from humans (n=127) and UK cattle (n=15). The antimicrobial resistance and virulence gene profiles of this collection of isolates were highly diverse. A substantial number of human isolates (32%, n=87) did not share more than 40% similarity (based on the Jaccard coefficient) with animal isolates. A further 43% of human isolates from the three countries (n=117) were at least 40% similar to each other and to five isolates from UK cattle and one each from Dutch chicken meat and a German dog; the members of this group usually harboured genes such as mph(A), mrx, aac(6’)-Ib, catB3, bla_OXA-1-like and bla_{CTX-M-group-1.} forty-four per cent of the MLST-typed isolates in this group belonged to ST131 (n=18) and 22% to ST405 (n=9), all from humans. Among animal isolates subjected to MLST (n=258), only 1.2% (n=3) were more than 70% similar to human isolates in gene profiles and shared the same MLST clonal complex with the corresponding human isolates. The results suggest that minimising human-to-human transmission is essential to control the spread of ESBL-positive E. coli in humans.

Four-year epidemiological study of extended-spectrum β-lactamase-producing Enterobacteriaceae in a French teaching hospital

Since the end of the last century resistance to oxyimino β-lactams has steadily increased in Enterobacteriaceae. In the present work we studied extended-spectrum β-lactamase (ESBL)-producing Enterobacteriaceae strains isolated in the teaching hospital of Clermont-Ferrand, France, between 2006 and 2009. A total of 1368 ESBL-producing isolates were collected. Most of these isolates (69%) were CTX-M-producing Escherichia coli. During the study, the clinical incidence increased by more than 400%, even in the emergency department, and especially in community-acquired infections, as is the case elsewhere in the world. Most of the ESBL-producing isolates remained susceptible to furans and fosfomycin, but only 50% to fluoroquinolons. In conclusion, ESBL-producing bacteria constantly increased during the study period. Unlike many studies, this increase was associated with the wide dissemination of three different CTX-M enzymes: CTX-M-14, CTX-M-15 and CTX-M-1.

Resistant gram-negative infections in the outpatient setting in Latin America

Latin America has a high rate of community-associated infections caused by multidrug-resistant Enterobacteriaceae relative to other world regions. A review of the literature over the last 10 years indicates that urinary tract infections (UTIs) by Escherichia coli, and intra-abdominal infections (IAIs) by E. coli and Klebsiella pneumoniae, were characterized by high rates of resistance to trimethoprim/sulfamethoxazole, quinolones, and second-generation cephalosporins, and by low levels of resistance to aminoglycosides, nitrofurantoin, and fosfomycin. In addition, preliminary data indicate an increase in IAIs by Enterobacteriaceae producing extended-spectrum β-lactamases, with reduced susceptibilities to third- and fourth-generation cephalosporins. Primary-care physicians in Latin America should recognize the public health threat associated with UTIs and IAIs by resistant Gram-negative bacteria. As the number of therapeutic options become limited, we recommend that antimicrobial prescribing be guided by infection severity, established patient risk factors for multidrug-resistant infections, acquaintance with local antimicrobial susceptibility data, and culture collection.

Detection of New Delhi metallo-beta-lactamase and extended-spectrum beta-lactamase genes in Escherichia coli isolated from mastitic milk samples

In this study, eight Escherichia coli isolates were obtained from milk samples of dairy cattle suffering from clinical/subclinical mastitis. Isolates were characterized for antimicrobial resistance traits and virulence genes. Results revealed that one isolate was harbouring New Delhi metallo-beta-lactamase gene (blaNDM ). Cloning and sequencing of the PCR amplicon confirmed the identity of the gene (GenBank accession no. KC769583) having 100% homology with blaNDM-5 (GenBank accession no. JN104597.1), and this isolate was susceptible to colistin, chloramphenicol and tetracycline only. Moreover, another isolate carried extended-spectrum beta-lactamase (ESBL) gene - blaCTX-M , and all isolates possessed blaTEM gene. Of the eight isolates, only one isolate was positive for shiga toxin gene (stx2), and none were harbouring stx1 gene. Occurrence of New Delhi metallo-beta-lactamase (blaNDM ) in one E. coli isolate and ESBL genes in other isolates poses a potential threat to human health following possible entry and spread through food chain.

Antimicrobial susceptibility profiles of human and piglet Clostridium difficile PCR-ribotype 078

In the last decade, outbreaks of nosocomial Clostridium difficile infections (CDI) occurred worldwide. A new emerging type, PCR-ribotype 027, was the associated pathogen. Antimicrobial susceptibility profiles of this type were extensively investigated and used to partly explain its spread. In Europe, the incidence of C. difficile PCR-ribotype 078 recently increased in humans and piglets. Using recommendations of the European Committee on Antimicrobial Susceptibility Testing (EUCAST) and the Clinical and Laboratory Standards Institute (CLSI) we studied the antimicrobial susceptibility to eight antimicrobials, mechanisms of resistance and the relation with previously prescribed antimicrobials in human (n=49) and porcine (n=50) type 078 isolates. Human and porcine type 078 isolates showed similar antimicrobial susceptibility patterns for the antimicrobials tested. In total, 37% of the isolates were resistant to four or more antimicrobial agents. The majority of the human and porcine isolates were susceptible to amoxicillin (100%), tetracycline (100%) and clindamycin (96%) and resistant to ciprofloxacin (96%). More variation was found for resistance patterns to erythromycin (76% in human and 59% in porcine isolates), imipenem (29% in human and 50% in porcine isolates) and moxifloxacin (16% for both human and porcine isolates). MIC values of cefuroxim were high (MICs >256 mg/L) in 96% of the isolates. Resistance to moxifloxacin and clindamycin was associated with a gyr(A) mutation and the presence of the erm(B) gene, respectively. A large proportion (96%) of the erythromycin resistant isolates did not carry the erm(B) gene. The use of ciprofloxacin (humans) and enrofloxacin (pigs) was significantly associated with isolation of moxifloxacin resistant isolates. Increased fluoroquinolone use could have contributed to the spread of C. difficile type 078.

Extended-spectrum cephalosporin-resistant Gram-negative organisms in livestock: an emerging problem for human health?

Escherichia coli, Salmonella spp. and Acinetobacter spp. are important human pathogens. Serious infections due to these organisms are usually treated with extended-spectrum cephalosporins (ESCs). However, in the past two decades we have faced a rapid increasing of infections and colonization caused by ESC-resistant (ESC-R) isolates due to production of extended-spectrum-β-lactamases (ESBLs), plasmid-mediated AmpCs (pAmpCs) and/or carbapenemase enzymes. This situation limits drastically our therapeutic armamentarium and puts under peril the human health. Animals are considered as potential reservoirs of multidrug-resistant (MDR) Gram-negative organisms. The massive and indiscriminate use of antibiotics in veterinary medicine has contributed to the selection of ESC-R E. coli, ESC-R Salmonella spp. and, to less extent, MDR Acinetobacter spp. among animals, food, and environment. This complex scenario is responsible for the expansion of these MDR organisms which may have life-threatening clinical significance. Nowadays, the prevalence of food-producing animals carrying ESC-R E. coli and ESC-R Salmonella (especially those producing CTX-M-type ESBLs and the CMY-2 pAmpC) has reached worryingly high values. More recently, the appearance of carbapenem-resistant isolates (i.e., VIM-1-producing Enterobacteriaceae and NDM-1 or OXA-23-producing Acinetobacter spp.) in livestock has even drawn greater concerns. In this review, we describe the aspects related to the spread of the above MDR organisms among pigs, cattle, and poultry, focusing on epidemiology, molecular mechanisms of resistance, impact of antibiotic use, and strategies to contain the overall problem. The link and the impact of ESC-R organisms of livestock origin for the human scenario are also discussed.

Approaching zero: temporal effects of a restrictive antibiotic policy on hospital-acquired Clostridium difficile, extended-spectrum β-lactamase-producing coliforms and meticillin-resistant Staphylococcus aureus

A restrictive antibiotic policy banning routine use of ceftriaxone and ciprofloxacin was implemented in a 450-bed district general hospital following an educational campaign. Monthly consumption of nine antibiotics was monitored in defined daily doses (DDDs) per 1000 patient-occupied bed-days (1000 pt-bds) 9 months before until 16 months after policy introduction. Hospital-acquired Clostridium difficile, meticillin-resistant Staphylococcus aureus (MRSA) and extended-spectrum β-lactamase (ESBL)-producing coliform cases per month/1000 pt-bds were identified and reviewed throughout the hospital. Between the first and final 6 months of the study, average monthly consumption of ceftriaxone reduced by 95% (from 46.213 to 2.129 DDDs/1000 pt-bds) and that for ciprofloxacin by 72.5% (109.804 to 30.205 DDDs/1000 pt-bds). Over the same periods, hospital-acquisition rates for C. difficile reduced by 77% (2.398 to 0.549 cases/1000 pt-bds), for MRSA by 25% (1.187 to 0.894 cases/1000 pt-bds) and for ESBL-producing coliforms by 17% (1.480 to 1.224 cases/1000 pt-bds). Time-lag modelling confirmed significant associations between ceftriaxone and C. difficile cases at 1 month (correlation 0.83; P<0.005), and between ciprofloxacin and ESBL-producing coliform cases at 2 months (correlation 0.649; P=0.002). An audit performed 3 years after the policy showed sustained reduction in C. difficile rates (0.259 cases/1000 pt-bds), with additional decreases for MRSA (0.409 cases/1000 pt-bds) and ESBL-producing coliforms (0.809 cases/1000 pt-bds). In conclusion, banning two antibiotics resulted in an immediate and profound reduction in hospital-acquired C. difficile, with possible longer-term effects on MRSA and ESBL-producing coliform rates. Antibiotic stewardship is fundamental in the control of major hospital pathogens.

Improving ante mortem diagnosis of Erysipelothrix rhusiopathiae infection by use of oral fluids for bacterial, nucleic acid, and antibody detection

Swine erysipelas is an economically important disease caused by Erysipelothrix rhusiopathiae. Pen-based collection of oral fluids has recently been utilized for monitoring infection dynamics in swine operations. The diagnostic performance of bacterial isolation, real-time PCR, and antibody detection by enzyme-linked immunosorbent assay (ELISA) and fluorescent microbead-based immunoassay (FMIA) methods were evaluated on pen-based oral fluid samples from pigs experimentally infected with E. rhusiopathiae (n=112) and from negative controls (n=32). While real-time PCR was a sensitive method with an overall detection rate of 100% (7/7 pens) one day post inoculation (dpi), E. rhusiopathiae was successfully isolated in only 28.6% (2/7 pens). Anti-Erysipelothrix IgM and IgG antibodies in pen-based oral fluids were detected at 4 to 5 dpi by FMIA and at 5 and 8 dpi by ELISA. The number of infected animals per pen, and in particular the timing of antimicrobial treatment administration impacted bacterial isolation and ELISA results. In oral fluid field samples, E. rhusiopathiae DNA was found in 23.3% of the samples while anti-E. rhusiopathiae IgG and IgM antibodies were found in 59.6% and 5.5% of the samples, respectively. The results suggest that an algorithm integrating oral fluids as specimen and real-time PCR and FMIA as detection methods is effective for earlier detection of an erysipelas outbreak thereby allowing for a more effective treatment outcome.