Application of Campylobacter jejuni Phages: Challenges and Perspectives

A broad host phage, CP6, for combating multidrug-resistant Campylobacter prevalent in poultry meat

Campylobacter is a major cause of bacterial foodborne diarrhea worldwide. Consumption of raw or undercooked chicken meat contaminated with Campylobacter is the most common causative agent of human infections. Given the high prevalence of contamination in poultry meat and the recent rise of multi-drug-resistant (MDR) Campylobacter strains, an effective intervention method of reducing bird colonization is needed. In this study, the Campylobacter-specific lytic phage CP6 was isolated from chicken feces. Phage CP6 exhibited a broad host range against different MDR Campylobacter isolates (97.4% of strains were infected). Some biological characteristics were observed, such as a good pH (3-9) stability and moderate temperature tolerance (<50 ℃). The complete genome sequence revealed a linear double-stranded DNA (178,350 bp, group II Campylobacter phage) with 27.51% GC content, including 209 predicted open reading frames, among which only 54 were annotated with known functions. Phylogenetic analysis of the phage major capsid protein demonstrated that phage CP6 was closely related to Campylobacter phage CPt10, CP21, CP20, IBB35, and CP220. CP6 phage exerted good antimicrobial effects on MDR Campylobacter in vitro culture and reduced CFUs of the host cells by up to 1-log compared with the control in artificially contaminated chicken breast meat. Our findings suggested the potential of CP6 phage as a promising antimicrobial agent for combating MDR Campylobacter in food processing.

Campylobacter prophage diversity reveals pervasive recombination between prophages from different Campylobacter species

IMPORTANCE

Prophages play an important role in shaping the genetic diversity and evolution of their hosts. Acquisition or loss of prophages can lead to genomic variations, including changes in the bacterial phenotype promoted by recombination events, genetic repertoire exchanges and dissemination of virulence factors, and antibiotic resistance. By studying prophages in Campylobacter species, scientists can gain insights into the evolutionary patterns, pathogenicity mechanisms, epidemiology, and population dynamics of these species. This has implications for public health, antibiotic resistance surveillance, and the development of targeted therapeutic approaches.

Study of Combined Effect of Bacteriophage vB3530 and Chlorhexidine on the Inactivation of Pseudomonas aeruginosa

BACKGROUND

Chlorhexidine (CHG) is a disinfectant commonly used in hospitals. However, it has been reported that the excessive use of CHG can cause resistance in bacteria to this agent and even to other clinical antibiotics. Therefore, new methods are needed to alleviate the development of CHG tolerance and reduce its dosage. This study aimed to explore the synergistic effects of CHG in combination with bacteriophage against CHG-tolerant Pseudomonas aeruginosa (P. aeruginosa) and provide ideas for optimizing disinfection strategies in clinical environments as well as for the efficient use of disinfectants.

METHODS

The CHG-tolerant P. aeruginosa strains were isolated from the First Affiliated Hospital of Wenzhou Medical University in China. The bacteriophage vB3530 was isolated from the sewage inlet of the hospital, and its genome was sequenced. Time-killing curve was used to determine the antibacterial effects of vB3530 and chlorohexidine gluconate (CHG). The phage sensitivity to 16 CHG-tolerant P. aeruginosa strains and PAO1 strain was detected using plaque assay. The emergence rate of resistant bacterial strains was detected to determine the development of phage-resistant and CHG-tolerant strains. Finally, the disinfection effects of the disinfectant and phage combination on the surface of the medical devices were preliminarily evaluated.

RESULTS

The results showed that (1) CHG combined with bacteriophage vB3530 significantly inhibited the growth of CHG-resistant P. aeruginosa and reduced the bacterial colony forming units (CFUs) after 24 h. (2) The combination of CHG and bacteriophage inhibited the emergence of phage-resistant and CHG-tolerant strains. (3) The combination of CHG and bacteriophage significantly reduced the bacterial load on the surface of medical devices.

CONCLUSIONS

In this study, the combination of bacteriophage vB3530 and CHG presented a combined inactivation effect to CHG-tolerant P. aeruginosa and reduced the emergence of strains resistant to CHG and phage. This study demonstrated the potential of bacteriophage as adjuvants to traditional disinfectants. The use of bacteriophage in combination with commercial disinfectants might be a promising method for controlling the spread of bacteria in hospitals.

Avian campylobacteriosis, prevalence, sources, hazards, antibiotic resistance, poultry meat contamination, and control measures: a comprehensive review

Avian campylobacteriosis is a vandal infection that poses human health hazards. Campylobacter is usually colonized in the avian gut revealing mild signs in the infected birds, but retail chicken carcasses have high contamination levels of Campylobacter spp. Consequently, the contaminated avian products constitute the main source of human infection with campylobacteriosis and result in severe clinical symptoms such as diarrhea, abdominal pain, spasm, and deaths in sensitive cases. Thus, the current review aims to shed light on the prevalence of Campylobacter in broiler chickens, Campylobacter colonization, bird immunity against Campylobacter, sources of poultry infection, antibiotic resistance, poultry meat contamination, human health hazard, and the use of standard antimicrobial technology during the chicken processing of possible control strategies to overcome such problems.

Full-scale industrial phage trial targeting Salmonella on pork carcasses

Phages have been suggested as promising biocontrol agents in food, but trials demonstrating the efficiency of phage treatment under industrial settings are missing. Here we performed a full-scale industrial trial to evaluate the efficacy of a commercial phage product to reduce the prevalence of naturally occurring Salmonella on pork carcasses. A total of 134 carcasses from potentially Salmonella positive finisher herds were chosen to be tested at the slaughterhouse based on the level of antibodies in the blood. During five consecutive runs, carcasses were directed into a cabin spraying phages, resulting in a dosage of approximately 2 × 107 phages per cm2 carcass surface. To evaluate the presence of Salmonella, a predefined area of one half of the carcass was swabbed before phage application and the other half 15 min after. A total of 268 samples were analysed by Real-Time PCR. Under these optimized test conditions, 14 carcasses were found positive before phage application, while only 3 carcasses were positive after. This work shows that phage application allows to achieve approximatively 79% reduction of Salmonella-positive carcasses and demonstrates that implementation of phage application in industrial settings can be used as an additional strategy to control foodborne pathogens.

Antimicrobial Drug Resistance in Poultry Production: Current Status and Innovative Strategies for Bacterial Control

The world population’s significant increase has promoted a higher consumption of poultry products, which must meet the specified demand while maintaining their quality and safety. It is well known that conventional antimicrobials (antibiotics) have been used in livestock production, including poultry, as a preventive measure against or for the treatment of infectious bacterial diseases. Unfortunately, the use and misuse of these compounds has led to the development and dissemination of antimicrobial drug resistance, which is currently a serious public health concern. Multidrug-resistant bacteria are on the rise, being responsible for serious infections in humans and animals; hence, the goal of this review is to discuss the consequences of antimicrobial drug resistance in poultry production, focusing on the current status of this agroeconomic sector. Novel bacterial control strategies under investigation for application in this industry are also described. These innovative approaches include antimicrobial peptides, bacteriophages, probiotics and nanoparticles. Challenges related to the application of these methods are also discussed.

Role of Bacteriophages for Optimized Health and Production of Poultry

The poultry sector is facing infections from Salmonella, Campylobacter, Listeria and Staphylococcus spp., and Escherichia coli, that have developed multidrug resistance aptitude. Antibiotics cause disturbances in the balance of normal microbiota leading to dysbiosis, immunosuppression, and the development of secondary infections. Bacteriophages have been reported to lower the colonization of Salmonella and Campylobacter in poultry. The specificity of bacteriophages is greater than that of antibiotics and can be used as a cocktail for enhanced antibacterial activity. Specie-specific phages have been prepared, e.g., Staphylophage (used against Staphylococcus bacteria) that specifically eliminate bacterial pathogens. Bacteriophage products, e.g., BacWash^TM and Ecolicide PX have been developed as antiseptics and disinfectants for effective biosecurity and biosafety measures. The success of phage therapy is influenced by time to use, the amount used, the delivery mechanism, and combination therapy with other therapeutics. It is a need of time to build a comprehensive understanding of the use of bacteriophages in poultry production. The current review thus focuses on mechanisms of bacteriophages against poultry pathogens, their applications in various therapeutics, impacts on the economy, and current challenges.

Campylobacter jejuni in Poultry: Pathogenesis and Control Strategies

C. jejuni is the leading cause of human foodborne illness associated with poultry, beef, and pork consumption. C. jejuni is highly prevalent in commercial poultry farms, where horizontal transmission from the environment is considered to be the primary source of C. jejuni. As an enteric pathogen, C. jejuni expresses virulence factors regulated by a two-component system that mediates C. jejuni's ability to survive in the host. C. jejuni survives and reproduces in the avian intestinal mucus. The avian intestinal mucus is highly sulfated and sialylated compared with the human mucus modulating C. jejuni pathogenicity into a near commensal bacteria in poultry. Birds are usually infected from two to four weeks of age and remain colonized until they reach market age. A small dose of C. jejuni (around 35 CFU/mL) is sufficient for successful bird colonization. In the U.S., where chickens are raised under antibiotic-free environments, additional strategies are required to reduce C. jejuni prevalence on broilers farms. Strict biosecurity measures can decrease C. jejuni prevalence by more than 50% in broilers at market age. Vaccination and probiotics, prebiotics, synbiotics, organic acids, bacteriophages, bacteriocins, and quorum sensing inhibitors supplementation can improve gut health and competitively exclude C. jejuni load in broilers. Most of the mentioned strategies showed promising results; however, they are not fully implemented in poultry production. Current knowledge on C. jejuni's morphology, source of transmission, pathogenesis in poultry, and available preharvest strategies to decrease C. jejuni colonization in broilers are addressed in this review.

From Farm to Fork: Streptococcus suis as a Model for the Development of Novel Phage-Based Biocontrol Agents

Bacterial infections of livestock threaten the sustainability of agriculture and public health through production losses and contamination of food products. While prophylactic and therapeutic application of antibiotics has been successful in managing such infections, the evolution and spread of antibiotic-resistant strains along the food chain and in the environment necessitates the development of alternative or adjunct preventive and/or therapeutic strategies. Additionally, the growing consumer preference for “greener” antibiotic-free food products has reinforced the need for novel and safer approaches to controlling bacterial infections. The use of bacteriophages (phages), which can target and kill bacteria, are increasingly considered as a suitable measure to reduce bacterial infections and contamination in the food industry. This review primarily elaborates on the recent veterinary applications of phages and discusses their merits and limitations. Furthermore, using Streptococcus suis as a model, we describe the prevalence of prophages and the anti-viral defence arsenal in the genome of the pathogen as a means to define the genetic building blocks that are available for the (synthetic) development of phage-based treatments. The data and approach described herein may provide a framework for the development of therapeutics against an array of bacterial pathogens.

Systematic review of products with potential application for use in the control of Campylobacter spp. in organic and free-range broilers

Campylobacter spp. are some of the most important food-borne zoonoses in Europe and broiler meat is considered the main source of Campylobacter infections. Organic and free-range broilers have access to outdoor reservoirs of Campylobacter and are more frequently infected at slaughter than the conventional broiler flocks. Limitations to biosecurity and treatment options in these production types calls for additional solutions. This review examines intervention methods with sufficient strength and quality, which are able to reduce the load of Campylobacter safely and efficiently and discuss their applicability in organic and free-range broiler production. Four different products passed the inclusion criteria and their quality examined: ferric tyrosine chelate, a prebiotic fermentation product of Saccharomyces cerevisiae, short-chain fatty acid butyrate coated on microbeads added to feed, and a mix of organic acids added to the drinking water. Though potential candidates for reducing Campylobacter in broilers were identified, there is a lack of large scale intervention studies that demonstrate an effect under field conditions of a free-range broiler production.

Application and challenge of bacteriophage in the food protection

In recent years, foodborne diseases caused by pathogens have been increasing. Therefore, it is essential to control the growth and transmission of pathogens. Bacteriophages (phages) have the potential to play an important role in the biological prevention, control, and treatment of these foodborne diseases due to their favorable advantages. Phages not only effectively inhibit pathogenic bacteria and prolong the shelf life of food, but also possess the advantages of specificity and an absence of chemical residues. Currently, there are many cases of phage applications in agriculture, animal disease prevention and control, food safety, and the treatment of drug-resistant disease. In this review, we summarize the recent research progress on phages against foodborne pathogenic bacteria, including Escherichia coli, Salmonella, Campylobacter, Listeria monocytogenes, Shigella, Vibrio parahaemolyticus, and Staphylococcus aureus. We also discuss the main issues and their corresponding solutions in the application of phages in the food industry. In recent years, although researchers have discovered more phages with potential applications in the food industry, most researchers use these phages based on their host spectrum, and the application environment is mostly in the laboratory. Therefore, the practical application of these phages in different aspects of the food industry may be unsatisfactory and even have some negative effects. Thus, we suggest that before using these phages, it is necessary to identify their specific receptors. Using their specific receptors as the selection basis for their application and combining phages with other phages or phages with traditional antibacterial agents may further improve their safety and application efficiency. Collectively, this review provides a theoretical reference for the basic research and application of phages in the food industry.

Phage Products for Fighting Antimicrobial Resistance

Antimicrobial resistance (AMR) has become a global public health issue and antibiotic agents have lagged behind the rise in bacterial resistance. We are searching for a new method to combat AMR and phages are viruses that can effectively fight bacterial infections, which have renewed interest as antibiotic alternatives with their specificity. Large phage products have been produced in recent years to fight AMR. Using the “one health” approach, this review summarizes the phage products used in plant, food, animal, and human health. In addition, the advantages and disadvantages and future perspectives for the development of phage therapy as an antibiotic alternative to combat AMR are also discussed in this review.

Phage-based technologies for highly sensitive luminescent detection of foodborne pathogens and microbial toxins: A review

Foodborne pathogens and microbial toxins are the main causes of foodborne illness. However, trace pathogens and toxins in foods are difficult to detect. Thus, techniques for their rapid and sensitive identification and quantification are urgently needed. Phages can specifically recognize and adhere to certain species of microbes or toxins due to molecular complementation between capsid proteins of phages and receptors on the host cell wall or toxins, and thus they have been successfully developed into a detection platform for pathogens and toxins. This review presents an update on phage-based luminescent detection technologies as well as their working principles and characteristics. Based on phage display techniques of temperate phages, reporter gene detection assays have been designed to sensitively detect trace pathogens by luminous intensity. By the host-specific lytic effects of virulent phages, enzyme-catalyzed chemiluminescent detection technologies for pathogens have been exploited. Notably, these phage-based luminescent detection technologies can discriminate viable versus dead microbes. Further, highly selective and sensitive immune-based assays have been developed to detect trace toxins qualitatively and quantitatively via antibody analogs displayed by phages, such as phage-ELISA (enzyme-linked immunosorbent assay) and phage-IPCR (immuno-polymerase chain reaction). This literature research may lead to novel and innocuous phage-based rapid detection technologies to ensure food safety.

Campylobacter Bacteriophage Cocktail Design Based on an Advanced Selection Scheme

Campylobacteriosis is a worldwide-occurring disease and has been the most commonly reported zoonotic gastrointestinal infection in the European Union in recent years. The development of successful phage-based intervention strategies will require a better understanding of phage–bacteria interactions to facilitate advances in phage cocktail design. Therefore, this study aimed to investigate the effects of newly isolated group II and group III phages and their combinations on current Campylobacter field strains. A continuous workflow for host range and efficiency of plating (EOP) value determination was combined with a qPCR-based phage group identification and a liquid-based planktonic killing assay (PKA). An advanced analysis scheme allowed us to evaluate phage cocktails by their efficacy in inhibiting bacterial population growth and the resulting phage concentrations. The results of this study indicate that data obtained from PKAs are more accurate than host range data based on plaque formation (EOP). Planktonic killing assays with Campylobacter appear to be a useful tool for a straightforward cocktail design. Results show that a group II phage vB_CcM-LmqsCP218-2c2 and group III phage vB_CjM-LmqsCP1-1 mixture would be most promising for practical applications against Campylobacter coli and Campylobacter jejuni.

Application of Bacteriophages to Limit Campylobacter in Poultry Production

Campylobacter is a major foodborne pathogen with over a million United States cases a year and is typically acquired through the consumption of poultry products. The common occurrence of Campylobacter as a member of the poultry gastrointestinal tract microbial community remains a challenge for optimizing intervention strategies. Simultaneously, increasing demand for antibiotic-free products has led to the development of several alternative control measures both at the farm and in processing operations. Bacteriophages administered to reduce foodborne pathogens are one of the alternatives that have received renewed interest. Campylobacter phages have been isolated from both conventionally and organically raised poultry. Isolated and cultivated Campylobacter bacteriophages have been used as an intervention in live birds to target colonized Campylobacter in the gastrointestinal tract. Application of Campylobacter phages to poultry carcasses has also been explored as a strategy to reduce Campylobacter levels during poultry processing. This review will focus on the biology and ecology of Campylobacter bacteriophages in poultry production followed by discussion on current and potential applications as an intervention strategy to reduce Campylobacter occurrence in poultry production.

Isolation and Characterization of Group III Campylobacter jejuni-Specific Bacteriophages From Germany and Their Suitability for Use in Food Production

Campylobacter spp. are a major cause of bacterial foodborne diarrhea worldwide. While thermophilic Campylobacter species asymptomatically colonize the intestines of chickens, most human infections in industrial countries have been attributed to consumption of chicken meat or cross-contaminated products. Bacteriophages (phages) are natural predators of bacteria and their use at different stages of the food production chain has been shown to reduce the public health burden of human campylobacteriosis. However, regarding regulatory issues, the use of lytic phages in food is still under discussion and evaluation. This study aims to identify lytic phages suitable for reducing Campylobacter bacteria along the food production chain. Therefore, four of 19 recently recovered phages were further characterized in detail for their lytic efficacy against different Campylobacter field strains and their suitability under food production settings at different temperatures and pH values. Based on the results of this study, the phages vB_CjM-LmqsCP1-4 and vB_CjM-LmqsCP1-5 appear to be promising candidates for the reduction of Campylobacter jejuni in food production settings.

Campylobacter phages use hypermutable polyG tracts to create phenotypic diversity and evade bacterial resistance

Phase variation is a common mechanism for creating phenotypic heterogeneity of surface structures in bacteria important for niche adaptation. In Campylobacter, phase variation occurs by random variation in hypermutable homonucleotide 7-11 G (polyG) tracts. To elucidate how phages adapt to phase-variable hosts, we study Fletchervirus phages infecting Campylobacter dependent on a phase-variable receptor. Our data demonstrate that Fletcherviruses mimic their host and encode hypermutable polyG tracts, leading to phase-variable expression of two of four receptor-binding proteins. This creates phenotypically diverse phage populations, including a sub-population that infects the bacterial host when the phase-variable receptor is not expressed. Such population dynamics of both phage and host promote co-existence in a shared niche. Strikingly, we identify polyG tracts in more than 100 phage genera, infecting more than 70 bacterial species. Future experimental work may confirm phase variation as a widespread strategy for creating phenotypically diverse phage populations.

Distribution of CRISPR Types in Fluoroquinolone-Resistant Campylobacter jejuni Isolates

To aid development of phage therapy against Campylobacter, we investigated the distribution of the clustered regularly interspaced short palindromic repeats (CRISPR) systems in fluoroquinolone (FQ)-resistant Campylobacter jejuni. A total of 100 FQ-resistant C. jejuni strains from different sources were analyzed by PCR and DNA sequencing to determine resistance-conferring mutation in the gyrA gene and the presence of various CRISPR systems. All but one isolate harbored 1-5 point mutations in gyrA, and the most common mutation was the Thr86Ile change. Ninety-five isolates were positive with the CRISPR PCR, and spacer sequences were found in 86 of them. Among the 292 spacer sequences identified in this study, 204 shared 93-100% nucleotide homology to Campylobacter phage D10, 44 showed 100% homology to Campylobacter phage CP39, and 3 had 100% homology with Campylobacter phage CJIE4-5. The remaining 41 spacer sequences did not match with any phages in the database. Based on the results, it was inferred that the FQ-resistant C. jejuni isolates analyzed in this study were potentially resistant to Campylobacter phages D10, CP39, and CJIE4-5 as well as some unidentified phages. These phages should be excluded from cocktails of phages that may be utilized to treat FQ-resistant Campylobacter.

Survival and Control of Campylobacter in Poultry Production Environment

Campylobacter species are Gram-negative, motile, and non-spore-forming bacteria with a unique helical shape that changes to filamentous or coccoid as an adaptive response to environmental stresses. The relatively small genome (1.6 Mbp) of Campylobacter with unique cellular and molecular physiology is only understood to a limited extent. The overall strict requirement of this fastidious microorganism to be either isolated or cultivated in the laboratory settings make itself to appear as a weak survivor and/or an easy target to be inactivated in the surrounding environment of poultry farms, such as soil, water source, dust, surfaces and air. The survival of this obligate microaerobic bacterium from poultry farms to slaughterhouses and the final poultry products indicates that Campylobacter has several adaptive responses and/or environmental niches throughout the poultry production chain. Many of these adaptive responses remain puzzles. No single control method is yet known to fully address Campylobacter contamination in the poultry industry and new intervention strategies are required. The aim of this review article is to discuss the transmission, survival, and adaptation of Campylobacter species in the poultry production environments. Some approved and novel control methods against Campylobacter species throughout the poultry production chain will also be discussed.

Isolation, host specificity and genetic characterization of Campylobacter specific bacteriophages from poultry and swine sources

The isolation and characterization of 304 Campylobacter specific bacteriophage isolates from broiler and swine sources is reported in this study. Genome size characterization determined by PFGE classified these isolates,called CAM1-CAM304, within the campylophages group II (n = 18) and group III (n = 286). Host range analyses showed a high host specificity and similar lytic spectrum among isolates of the same group. Campylophages of group II infected C. jejuni, C. coli and even a C. fetus strain whereas those of group III only infected C. jejuni strains. The most promising 59 campylophage candidates were selected according to their lytic activity and their genetic diversity was analyzed by RFLP using SmiI and HhaI endonucleases for group II and III campylophages, respectively. Moreover, RAPD-PCR technique was for the first time assessed in the genetic characterization of campylophages and it was shown to be effective only for those of group II. Bacteriophage isolates grouped in a same genotype displayed different host ranges, therefore, 13 campylophages of group II and eight of group III were differentiated considering all the approaches assayed. An in-depth analysis of these bacteriophages will be performed to confirm their promising potential for the biocontrol of Campylobacter within the farm to fork process.

Campylobacter sp.: Pathogenicity factors and prevention methods-new molecular targets for innovative antivirulence drugs?

Infections caused by bacterial species from the genus Campylobacter are one of the four main causes of strong diarrheal enteritis worldwide. Campylobacteriosis, a typical food-borne disease, can range from mild symptoms to fatal illness. About 550 million people worldwide suffer from campylobacteriosis and lethality is about 33 million p.a. This review summarizes the state of the current knowledge on Campylobacter with focus on its specific virulence factors. Using this knowledge, multifactorial prevention strategies can be implemented to reduce the prevalence of Campylobacter in the food chain. In particular, antiadhesive strategies with specific adhesion inhibitors seem to be a promising concept for reducing Campylobacter bacterial load in poultry production. Antivirulence compounds against bacterial adhesion to and/or invasion into the host cells can open new fields for innovative antibacterial agents. Influencing chemotaxis, biofilm formation, quorum sensing, secretion systems, or toxins by specific inhibitors can help to reduce virulence of the bacterium. In addition, the unusual glycosylation of the bacterium, being a prerequisite for effective phase variation and adaption to different hosts, is yet an unexplored target for combating Campylobacter sp. Plant extracts are widely used remedies in developing countries to combat infections with Campylobacter. Therefore, the present review summarizes the use of natural products against the bacterium in an attempt to stimulate innovative research concepts on the manifold still open questions behind Campylobacter towards improved treatment and sanitation of animal vectors, treatment of infected patients, and new strategies for prevention. KEY POINTS: • Campylobacter sp. is a main cause of strong enteritis worldwide. • Main virulence factors: cytolethal distending toxin, adhesion proteins, invasion machinery. • Strong need for development of antivirulence compounds.

Looking into the future of phage-based control of zoonotic pathogens in food and animal production

Using bacteriophages (phages) to control zoonotic pathogens in food and animal production is a realistic and promising antimicrobial approach. Recent studies have demonstrated their efficacy and safety, yet bringing phage products on the market remains a challenge. Here we summarize the procedure for advancing phage applications from the laboratory to simplified model systems and testing in pilot scale, to farms and food industries. We highlight the most important contributions concerning phages in food matrices and animal guts, and propose directions for future research required to understand interactions in such complex systems. Finally, we propose a holistic approach combining a data repository with modelling, multi-omic techniques and data analysis to modernize phage-based control of zoonotic pathogens.

New and alternative strategies for the prevention, control, and treatment of antibiotic-resistant Campylobacter

Campylobacter is an enteric pathogen and a leading bacterial cause of diarrhea worldwide. It is widely distributed in food animal species and is transmitted to humans primarily through the foodborne route. While generally causing self-limited diarrhea in humans, Campylobacter may induce severe or systemic infections in immunocompromised or young/elderly patients, which often requires antibiotic therapy with the first-line antibiotics including fluoroquinolones and macrolides. Over the past decades, Campylobacter has acquired resistance to these clinically significant antibiotics, compromising the effectiveness of antibiotic treatments. To address this concern, many studies have been conducted to advance novel and alternative measures to control antibiotic-resistant Campylobacter in animal reservoirs and in the human host. Although some of these undertakings have yielded promising results, efficacious and reliable alternative approaches are yet to be developed. In this review article, we will describe Campylobacter-associated disease spectrums and current treatment options, discuss the state of antibiotic resistance and alternative therapies, and provide an evaluation of various approaches that are being developed to control Campylobacter infections in animal reservoirs and the human host.

Molecular Mechanisms and Epidemiology of Fosfomycin Resistance in Staphylococcus aureus Isolated From Patients at a Teaching Hospital in China

Staphylococcus aureus is a major cause of hospital- and community-acquired infections placing a significant burden on the healthcare system. With the widespread of multidrug-resistant bacteria and the lack of effective antibacterial drugs, fosfomycin has gradually attracted attention as an "old drug." Thus, investigating the resistance mechanisms and epidemiology of fosfomycin-resistant S. aureus is an urgent requirement. In order to investigate the mechanisms of resistance, 11 fosfomycin-resistant S. aureus isolates were analyzed by PCR and sequencing. The genes, including fosA, fosB, fosC, fosD, fosX, and tet38, as well as mutations in murA, glpT, and uhpT were identified. Quantitative real-time PCR (qRT-PCR) was conducted to evaluate the expression of the target enzyme gene murA and the efflux pump gene tet38 under the selection pressure of fosfomycin. Furthermore, multilocus sequence typing (MLST) identified a novel sequence type (ST 5708) of S. aureus strains. However, none of the resistant strains carried fosA, fosB, fosC, fosD, and fosX genes in the current study, and 12 distinct mutations were detected in the uhpT (3), glpT (4), and murA (5) genes. qRT-PCR revealed an elevated expression of the tet38 gene when exposed to increasing concentration of fosfomycin among 8 fosfomycin-resistant S. aureus strains and reference strain ATCC 29213. MLST analysis categorized the 11 strains into 9 STs. Thus, the mutations in the uhpT, glpT, and murA genes might be the primary mechanisms underlying fosfomycin resistance, and the overexpression of efflux pump gene tet38 may play a major role in the fosfomycin resistance in these isolates.