Antibiotics: Has the magic gone?

The emergence of antibiotic resistant bacteria has diminished the efficacy of several antibiotics that were used to treat infectious diseases in humans and animals. In recent years, the problem of antibiotic resistance has become more apparent as increasing numbers of bacteria have acquired resistance to multiple antibiotics. Antibiotics inhibit bacterial growth through a variety of mechanisms including inhibition of cell wall or protein synthesis, interference with DNA (or RNA) replication, and disruption of metabolic pathways or cell membrane. Bacteria develop resistance through genetic mutations or by acquiring resistant genes involved in the production of antibiotic degrading enzymes, overproduction of target molecules, efflux pumps to drain out antibiotics, and/or altered cell wall permeability to survive adverse physiological conditions. Published literature suggests that sub‐therapeutic feeding of food animals for growth promotion along with casual use of antibiotics in household products such as soaps and creams is contributing to increased antimicrobial resistance in the environment. If steps are not taken to minimize selective pressure on bacteria, the effectiveness of antibiotics (hailed as ‘magic bullets’) may be marginalized. Important steps in the judicious use of antibiotics on the farm are: (1) education of farmers on the pitfalls of using antibiotics sub‐therapeutically in the production of food animals; (2) development of animal production practices that reduce dependence on antibiotics; and (3) development of manure disposal practices that minimize the spread of residual antibiotics and antibiotic resistant bacteria into the environment. In addition, educating the general public on the use and misuse of antibiotics in daily life is also important if there is to be any significant impact on reducing the environmental spread of antibiotic resistance. Copyright © 2006 Society of Chemical Industry     

Antimicrobial resistance: A global emerging threat to public health systems

Antimicrobial resistance (AMR) became in the last two decades a global threat to public health systems in the world. Since the antibiotic era, with the discovery of the first antibiotics that provided consistent health benefits to human medicine, the misuse and abuse of antimicrobials in veterinary and human medicine have accelerated the growing worldwide phenomenon of AMR. This article presents an extensive overview of the epidemiology of AMR, with a focus on the link between food producing-animals and humans and on the legal framework and policies currently implemented at the EU level and globally. The ways of responding to the AMR challenges foresee an array of measures that include: designing more effective preventive measures at farm level to reduce the use of antimicrobials; development of novel antimicrobials; strengthening of AMR surveillance system in animal and human populations; better knowledge of the ecology of resistant bacteria and resistant genes; increased awareness of stakeholders on the prudent use of antibiotics in animal productions and clinical arena; and the public health and environmental consequences of AMR. Based on the global nature of AMR and considering that bacterial resistance does not recognize barriers and can spread to people and the environment, the article ends with specific recommendations structured around a holistic approach and targeted to different stakeholders.     

Characterisation of anti‐Staphylococcus aureus activity of quercetin

Although many antibiotics are available for the treatment of bacterial infections, the emergence and global spread of antibiotic‐resistant bacteria is a community‐wide problem. To overcome this problem, we must explore alternative antimicrobials. This study investigated the antibacterial properties of quercetin, a flavonoid present in vegetables and fruits. Quercetin was tested against gram‐positive and gram‐negative bacteria and was found to exert selective antibacterial activity against Staphylococcus aureus, including methicillin‐resistant S. aureus (MRSA), and Staphylococcus epidermidis. Some clinical MRSA strains showed remarkable susceptibility to quercetin. In combination with antibiotics, such as oxacillin, ampicillin, vancomycin, gentamicin, and erythromycin, quercetin showed markedly enhanced antibacterial activity against MRSA. We also report quercetin‐induced aggregation of S. aureus cells; the morphological changes in these cells, as assessed by electron microscopy; and the colony‐spreading ability of quercetin‐sensitive MRSA, all of which revealed the unique antibacterial properties of quercetin against S. aureus.     

Antibiotic resistance mechanism and diagnosis of common foodborne pathogens based on genotypic and phenotypic biomarkers

The emergence of antibiotic-resistant bacteria due to the overuse or inappropriate use of antibiotics has become a significant public health concern. The agri-food chain, which serves as a vital link between the environment, food, and human, contributes to the large-scale dissemination of antibiotic resistance, posing a concern to both food safety and human health. Identification and evaluation of antibiotic resistance of foodborne bacteria is a crucial priority to avoid antibiotic abuse and ensure food safety. However, the conventional approach for detecting antibiotic resistance heavily relies on culture-based methods, which are laborious and time-consuming. Therefore, there is an urgent need to develop accurate and rapid tools for diagnosing antibiotic resistance in foodborne pathogens. This review aims to provide an overview of the mechanisms of antibiotic resistance at both phenotypic and genetic levels, with a focus on identifying potential biomarkers for diagnosing antibiotic resistance in foodborne pathogens. Furthermore, an overview of advances in the strategies based on the potential biomarkers (antibiotic resistance genes, antibiotic resistance-associated mutations, antibiotic resistance phenotypes) for antibiotic resistance analysis of foodborne pathogens is systematically exhibited. This work aims to provide guidance for the advancement of efficient and accurate diagnostic techniques for antibiotic resistance analysis in the food industry.     

Phages and their lysins: Toolkits in the battle against foodborne pathogens in the postantibiotic era

Worldwide, foods waste caused by putrefactive organisms and diseases caused by foodborne pathogens persist as public health problems even with a plethora of modern antimicrobials. Our over reliance on antimicrobials use in agriculture, medicine, and other fields will lead to a postantibiotic era where bacterial genotypic resistance, phenotypic adaptation, and other bacterial evolutionary strategies cause antimicrobial resistance (AMR). This AMR is evidenced by the emergence of multiple drug-resistant (MDR) bacteria and pan-resistant (PDR) bacteria, which produces cross-contamination in multiple fields and poses a more serious threat to food safety. A “red queen premise” surmises that the coevolution of phages and bacteria results in an evolutionary arms race that compels phages to adapt and survive bacterial antiphage strategies. Phages and their lysins are therefore useful toolkits in the design of novel antimicrobials in food protection and foodborne pathogens control, and the modality of using phages as a targeted vector against foodborne pathogens is gaining momentum based on many encouraging research outcomes. In this review, we discuss the rationale of using phages and their lysins as weapons against spoilage organisms and foodborne pathogens, and outline the targeted conquest or dodge mechanism of phages and the development of novel phage prospects. We also highlight the implementation of phages and their lysins to control foodborne pathogens in a farm–table–hospital domain in the postantibiotic era.     

噬菌体控制主要食源性致病菌的研究进展

食源性细菌疾病是当今世界上最广泛的公共卫生问题之一。由抗生素滥用导致的耐药菌株出现,以及抗生素禁用,使得人们对食源性细菌疾病的控制更加困难。噬菌体是细菌的天敌,具有感染并裂解细菌的功能,与抗生素相比,噬菌体制剂具有特异性强、自我增殖快、抗菌能力强、研发时间短等优点,因此近年来有关噬菌体作为抗菌制剂的研究受到普遍关注。本文就噬菌体在食源性病原微生物控制方面的应用研究进展作一综述,以期为噬菌体及其制剂在保障动物性食品安全领域的深入研究提供一定的参考。     

The emergence and spread of antibiotic resistance in food-borne bacteria

Since the early 1990s there has been a dramatic increase in resistance to antimicrobial drugs in Salmonella enterica and Campylobacter spp., and to a lesser extent in Vero cytotoxin-producing Escherichia coli O157 from cases of human infection in developed countries. For S. Typhimurium a particularly important aspect of this increase has been the widespread dissemination of a multiply drug-resistant (MR) strain of definitive phage type (DT) 104 in food animals since the early 1990s. The use of antimicrobials for prophylaxis in food producing animals has been an important factor in the emergence of strains with resistance to certain antimicrobials. It is hoped that recently introduced Codes of Practice for the prophylactic use of antimicrobials in food animals will result in a decline in the occurrence of drug resistant strains in the food chain.     

Antibiotic susceptibility of Bifidobacterium thermophilum and Bifidobacterium pseudolongum isolates from animal sources

The widespread use of antimicrobial substances has led to resistant populations of microorganisms in several ecosystems. In animal husbandry, the application of antibiotics has contributed to resistance development in pathogenic and commensal bacteria. These strains or their resistance genes can be spread along several ecological routes, including the food chain. Antibiotic resistance is important in terms of the safety of industrial strains, such as probiotics for food and feed. Bifidobacterium thermophilum and Bifidobacterium pseudolongum are known to comprise the major part of the bifidobacterial microbiota in the gut and feces of cattle and pigs. In this study, the antimicrobial susceptibility in bifidobacterial isolates of these species was investigated. Isolates from the beef and pork production chain were identified and typed to strain level, and the antimicrobial susceptibility level was tested to a set of antibiotics. Isolates with low susceptibility levels were screened by PCR for already described resistance genes. Strains atypically resistant to clindamycin, erythromycin, and tetracycline were determined. The resistance genes tet(O), tet(W), and erm(X) were detected in the bifidobacterial species that were examined.     

Emergence and Transfer of Antibacterial Resistance

There is increased public and scientific interest regarding the administration of therapeutic and subtherapeutic antimicrobials to animals. This is due primarily to the emergence and dissemination of multiple antibiotic resistant zoonotic bacterial pathogens. The debate regarding antimicrobial use in animals and subsequent human health implications has been going on for over 30 yr. This was initiated by the release of the Swann report in the United Kingdom in 1969. While this issue has triggered a tremendous controversy, there is still no agreement on the significance of antimicrobial use in animals and (or) resistance in bacterial isolates from animals on the development and dissemination of antibiotic resistance among human bacterial pathogens. Contributing to the controversy is the isolation of bacterial pathogens of animal and human origin that are increasingly resistant to most frontline antibiotics, including third-generation cephalosporins, aminoglycosides, and even fluoroquinolones. Recent studies have demonstrated that the majority of these multiple antimicrobial resistant phenotypes are obtained by the acquisition of external genes that may provide resistance to an entire class of antimicrobials. A number of these resistance genes have been associated with large, transferable, extra-chromosomal DNA elements, called plasmids, on which may be other DNA mobile elements, termed transposons and integrons. These DNA mobile elements have been shown to possess genetic determinants for several different antimicrobial resistance mechanisms are largely responsible for the rapid dissemination of resistance genes among different bacterial genera and species. Although the impact of a dairy practitioner or producer may seem small with regards to the emergence and dissemination of bacterial antimicrobial resistance, it is critical that we understand the importance of appropriate antimicrobial therapy from a broader perspective in the dairy production environment.     

High prevalence of antimicrobial‐resistant Escherichia coli from animals at slaughter: a food safety risk

BACKGROUND: There has been concern about the increase of antimicrobial resistant bacteria and protection of animal and public health, along with food safety. In the present study, we evaluate the incidence of antimicrobial resistance among 192 strains of Escherichia coli isolated from faecal samples of healthy food‐producing animals at slaughter in Portugal. RESULTS: Ninety‐seven % of the pig isolates, 74% from sheep and 55% from cattle were resistant to one or more antimicrobial agents, with the resistances to ampicillin, streptomycin, tetracycline and trimethoprim–sulfamethoxazole the most common phenotype detected. Genes encoding resistance to antimicrobial agents were detected in most of the resistant isolates. Ninety‐three % of the resistant isolates were included in the A or B1 phylogenetic groups, and the virulence gene fimA (alone or in association with papC or aer genes) was detected in 137 of the resistant isolates. Five isolates from pigs belonging to phylogroup B2 and D were resistant to five different antimicrobial agents. CONCLUSION: Our data shows a high percentage of antibiotic resistance in E. coli isolates from food animals, and raises important questions in the potential impact of antibiotic use in animals and the possible transmission of resistant bacteria to humans through the food chain. © 2012 Society of Chemical Industry     

2004—2012年分离自北京口岸进出口食品的沙门菌耐药性分析

目的 了解北京口岸进出口食品中分离沙门菌的耐药状况及耐药谱情况,分析耐药趋势,为制定食品安全监管措施和抗生素的使用提供依据。方法 对65株本实验室分离的沙门菌以及17株参比菌株,共82株沙门菌采用Kindy-Bauer(KB)法检测其对15种抗生素的敏感性,根据美国临床实验室标准化研究所(CLSI)标准进行判断,并对药敏试验结果进行数据分析。结果 65株沙门菌分离株除对头孢吡肟、头孢曲松、阿米卡星、头孢噻肟全部敏感外,对其余11种抗生素均有不同程度的耐药,其中氨苄西林耐药率最高为16.9%(11/65),其次为哌拉西林(13.8%,9/65)、四环素(13.8%,9/65)、卡那霉素(9.2%,6/65)和链霉素(7.7%,5/65)。在所有65株沙门菌分离株中,对1种抗生素耐药的菌株共11株,占16.9%(11/65),对2种抗生素耐药的菌株为1株,占1.5%(1/65),对3种及以上抗生素耐药的多重耐药株为7株,多重耐药率为10.8%(7/65)。结论 北京口岸进出口食品中分离的沙门菌对多种抗生素耐药。     

Spread of Antibiotic Resistant Bacteria from Food of Animal Origin to Humans and Vice Versa

Food-related bacteria are a very diverse population. They can be found in environment where food and feed is produced and handled. Nowadays, the foodborne zoonoses of greatest concern are campylobacteriosis, salmonellosis and Verotoxigenic Escherichia coli, and antibiotic resistance in these pathogens is an emerging health issue. Studies have been published about antibiotic resistant bacteria in different ecological niches. In our study, we found 40% of samples from food of animal origin contained bacteria resistant to one or more antibiotics. Without the interdisciplinary concept “one world one medicine one health”, bacteria will continue to produce offspring that are multiresistant to antibiotics.     

Phenotypic and Genotypic Antimicrobial Resistance Traits of Foodborne Staphylococcus aureus Isolates from Shanghai

Staphylococcus aureus is a recognized pathogen in humans, which causes nosocomial infections and food poisoning. The transmission of antibiotic resistant S. aureus (ARSA), especially methicillin‐resistant S. aureus, between food products and humans has become a serious problem. Hence, it is necessary to monitor S. aureus through the food supply chain. In this study, the disk diffusion method and epsilometer test were performed to determine the prevalence of ARSA in 78 foodborne isolates using 18 antibiotics. The highest resistance frequency was found for penicillin G (74.4%), followed by erythromycin (59.0%) and clindamycin (44.9%), whereas no vancomycin‐resistant isolates were found. The 78 isolates could be subtyped into 31 resistance profiles and 11 clusters based on their antimicrobial susceptibility. Furthermore, Polymerase chain reaction (PCR) screening for the presence of 13 genes conferring antibiotic resistance was conducted. The presence of resistance genes was relatively high: bla_TEM (80.8%), ermB (41.0%), grlA (38.5%), ermC (35.9%), and aac6’/aph2” (35.9%). The incidence of antibiotic resistance was significantly correlated to food types (p = 0.018), with isolates from meat and raw milk more resistant to antibiotics than those from frozen food and vegetables.     

Emergence of Antibiotic Resistance in Listeria monocytogenes Isolated from Food Products: A Comprehensive Review

Listeria monocytogenes is an opportunistic pathogen that has been involved in several deadly illness outbreaks. Future outbreaks may be more difficult to manage because of the emergence of antibiotic resistance among L. monocytogenes strains isolated from food products. The present review summarizes the available evidence on the emergence of antibiotic resistance among L. monocytogenes strains isolated from food products and the possible ways this resistance has developed. Furthermore, the resistance of food L. monocytogenes isolates to antibiotics currently used in the treatment of human listeriosis such as penicillin, ampicillin, tetracycline, and gentamicin, has been documented. Acquisition of movable genetic elements is considered the major mechanism of antibiotic resistance development in L. monocytogenes. Efflux pumps have also been linked with resistance of L. monocytogenes to some antibiotics including fluoroquinolones. Some L. monocytogenes strains isolated from food products are intrinsically resistant to several antibiotics. However, factors in food processing chains and environments (from farm to table) including extensive or sub‐inhibitory antibiotics use, horizontal gene transfer, exposure to environmental stresses, biofilm formation, and presence of persister cells play crucial roles in the development of antibiotic resistance by L. monocytogenes.     

中国食源性单核细胞增生李斯特菌耐药特征分析

目的研究中国22个省市自治区9类食品中分离的单核细胞增生李斯特菌的耐药特征。方法采用微量肉汤稀释法测定了1 069株单核细胞增生李斯特菌对庆大霉素、氨苄西林、青霉素、四环素、强力霉素、亚胺培南、红霉素、环丙沙星、左旋氧氟沙星、头孢噻吩、利福平、万古霉素、氯霉素、氨苄西林/舒巴坦酸和复方新诺明15种抗生素的耐药性。结果 1 069株单核细胞增生李斯特菌耐药率为6.92%,主要耐受的抗生素有四环素、强力霉素、红霉素、氯霉素和环丙沙星,并出现了多重耐药株。在不同食品来源中,分离自速冻米面制品的菌株耐药率最高,为9.64%。在22个省市自治区中,耐药率前3位的是:甘肃、吉林、福建,分别为27.3%、20.4%和17.4%。结论中国食源性单核细胞增生李斯特菌的耐药率较低,不同地区、不同食物来源耐药率差异较大,仍要加强对生产和临床使用抗生素的管理,减缓单核细胞增生李斯特菌耐药趋势的上升。     

The effects of sublethal doses of essential oils and their constituents on antimicrobial susceptibility and antibiotic resistance among food-related bacteria: A review

BackgroundEssential oils (EOs) and their individual constituents (ICs) have demonstrated strong and wide-spectrum antimicrobial activities against food-related bacteria. Frequently, the concentrations of EOs or ICs required to inhibit bacteria in foods are higher than those that are organoleptically acceptable, and their use at sublethal concentrations in combination with other preservation technologies has been proposed.Scope and approachBacteria have the capacity to develop physiological responses to sublethal growth conditions, which can lead to decreased susceptibility toward the same or other stressing agents, including resistance to antibiotics. Despite this knowledge, studies regarding the efficacy of EOs and ICs have mostly focused on doses that inactivate target bacteria in laboratorial media or in real foods, while less is known about the implications of their use at sublethal concentrations on bacterial susceptibility to antimicrobials, physical processes and antibiotic resistance. This review presents the available studies focused on the effects of the exposure of food-related bacteria to EOs or ICs at sublethal concentrations on alterations in susceptibility to homologous or heterologous stressing agents, including antibiotic-resistance, and related physiological responses in bacteria experiencing these stresses.Key findings and conclusionsThe findings of the available studies show that changes in susceptibility to antimicrobials and physical procedures as well as in antibiotic resistance vary with the target bacterium and the applied stress condition. Moreover, the observed stress-induced physiological responses have been varied. Notably, for the majority of the studies, the exposure of food-related bacteria to these stresses has not resulted in relevant changes in the sensitivity of the bacteria to antimicrobials, physical processes or antibiotics, which indicate that changes in bacterial sensitivity are not a major problem when considering the use of EOs or ICs in food preservation.     

抗菌材料在食品包装中的研究进展

食品抗菌包装可以有效抑制被包装食品所处环境中微生物的生长,延长食品的货架期,保证食品品质,在食品领域的地位越发重要。本文阐述了抗菌材料作用机理,介绍了常用的有机抗菌剂、无机抗菌剂和天然抗菌剂,并对食品抗菌包装的5 种实现方式进行了比较。对国内外近年来抗菌材料的研究进展,特别是对天然抗菌剂的应用做了详细说明。最后,结合目前抗菌包装膜和抗菌纸的生产现状,对食品抗菌包装的未来发展趋势和研究重点进行展望。     

抗菌肽对于病原微生物的抗菌及耐药机制

抗菌肽作为多种生物抵抗病原体的第一道防线,可以作为生物体内的天然免疫屏障,也可以在食品工业中用作天然防腐剂。该文叙述了抗菌肽杀灭细菌的作用机制以及微生物耐受抗菌肽的基本原理。无论是抗菌肽对病原微生物的抗菌作用还是病原微生物的耐抗性,其主要机制都与膜的生理功能和胞质成分变化有关。对于抗菌,主要是通过阻碍或破坏细胞壁的形成、与胞内靶位点结合以及抑制主要的脱氧核糖核酸（DNA）复制酶从而达到抗菌效果。微生物对于抗菌肽耐药性的实现主要是有机体通过先天的组成型抗性和后期的诱导型抗性。这些信息可能有助于选择最佳的抗菌肽,并建立有效的使用途径。     

Antimicrobial activity of whey protein isolate edible films with essential oils against food spoilers and foodborne pathogens

The use of antimicrobial edible film is proposed as a means of improving food safety and extending the shelf-life of food systems by controlling the release of antimicrobials on food surfaces. In this work we first selected and studied 8 different essential oils (EOs) from plants, namely, oregano, clove, tea tree, coriander, mastic thyme, laurel, rosemary, and sage as natural antimicrobials against 2 gram-positive bacteria (Listeria innocua and Staphylococcus aureus) and 2 gram-negative bacteria (Salmonella enteritidis and Pseudomona fragi) by using the agar disk diffusion method. EOs from oregano, clove, and tea tree produced the largest surfaces of inhibition against the growth of the 4 bacterial strains tested. Second and following the assessment of compatibility, stable antimicrobial edible films based on whey protein isolate (WPI) with increasing concentrations (0.5% to 9%) of the 8 EOs were developed and tested for antimicrobial activity against the same gram-positive and gram-negative bacteria. WPI-edible films incorporating oregano or clove EO were found to have the most intense inhibitory effect of microbial growth. The bacterial strain gram-negative P. fragi presented the less susceptibility to the effect of those films. Moreover, only the edible films based on these 2 EOs were active against all 4 studied microorganisms. On the other hand, the edible films incorporating tea tree, coriander, mastic thyme, laurel, rosemary, or sage EOs even at high concentrations (7% to 9%) did not cause any antimicrobial effect against the pathogens S. aureus or S. enteritidis. PRACTICAL APPLICATION: Potential applications of this technology can introduce direct benefits to the food industry by improving safety and microbial product quality. The results of this research have direct application in the food industry with potential applications in various foodstuffs, including meat and poultry products where the control of spoilage bacteria such as P. fragi throughout their chilled storage or the improvement of food safety by controlling pathogens such as S. enteritidis are topics of particular interest for the industry.     

安全的天然食品防腐剂细菌素

细菌素是细菌产生的可以杀死或抑制别的细菌生长的抗菌蛋白。许多乳酸菌(LAB)产生各种各样的细菌素，其中的尼生素是唯一的在食品中作为防腐剂广泛使用的细菌素。文章综述了以尼生素为重点对细菌素与抗生素的区别、活性细菌素分子的形成以及其在食品中的应用，并比较了这两种类型的分子的合成、作用模式、抵抗力和安全性。