Remarkable enhancement of cinnamaldehyde antimicrobial activity encapsulated in capped mesoporous nanoparticles: A new "nanokiller" approach in the era of antimicrobial resistance

Combating antimicrobial resistance is one of the biggest health challenges because of the ineffectiveness of standard biocide treatments. This challenge could be approached using natural products, which have demonstrated powerful therapeutics against multidrug-resistant microbes. In the present work, a nanodevice consisting of mesoporous silica nanoparticles loaded with an essential oil component (cinnamaldehyde) and functionalized with the polypeptide ε-poly-l-lysine is developed and used as an antimicrobial agent. In the presence of the corresponding stimuli (i.e., exogenous proteolytic enzymes from bacteria or fungi), the polypeptide is hydrolyzed, and the cinnamaldehyde delivery is enhanced. The nanodevice's release mechanism and efficacy are evaluated in vitro against the pathogenic microorganisms Escherichia coli, Staphylococcus aureus, and Candida albicans. The results demonstrate that the new device increases the delivery of the cinnamaldehyde via a biocontrolled uncapping mechanism triggered by proteolytic enzymes. Moreover, the nanodevice notably improves the antimicrobial efficacy of cinnamaldehyde when compared to the free compound, ca. 52-fold for E. coli, ca. 60-fold for S. aureus, and ca. 7-fold for C. albicans. The enhancement of the antimicrobial activity of the essential oil component is attributed to the decrease of its volatility due to its encapsulation in the porous silica matrix and the increase of its local concentration when released due to the presence of microorganisms.

An explicit review and proposal of an integrated framework system to mitigate the baffling complexities induced by road dust-associated contaminants

Road dust-associated contaminants (RD-AC) are gradually becoming a much thornier problem, as their monotonous correlations render them carcinogenic, mutagenic, and teratogenic. While many studies have examined the harmful effects of road dust on both humans and the environment, few studies have considered the co-exposure risk and gradient outcomes given the spatial extent of RD-AC. In this spirit, this paper presents in-depth elucidation into the baffling complexities induced by both major and emerging contaminants of road dust through a panorama-to-profile up-to-date review of diverse studies unified by the goal of advancing innovative methods to mitigate these contaminants. The paper thoroughly explores the correlations between RD-AC and provides insights to understand their potential in dispersing saprotrophic microorganisms. It also explores emerging challenges and proposes a novel integrated framework system aimed at thermally inactivating viruses and other pathogenic micro-organisms commingled with RD-AC. The main findings are: (i) the co-exposure risk of both major and emerging contaminants add another layer of complexity, highlighting the need for more holistic framework strategies, given the geospatial morphology of these contaminants; (ii) road dust contaminants show great potential for extended prevalence and severity of viral particles pollution; (iii) increasing trend of environmentally persistent free radicals (EPFRs) in road dust, with studies conducted solely in China thus far; and (iv) substantial hurdle exists in acquiring data concerning acute procedural distress and long-term co-exposure risk to RD-ACs. Given the baffling complexities of RD-ACs, co-exposure risk and the need for innovative mitigation strategies, the study underscore the significance of establishing robust systems for deep road dust contaminants control and future research efforts while recognizing the interconnectivity within the contaminants associated with road dust.

First report of Anaplasma spp., Ehrlichia spp., and Rickettsia spp. in Amblyomma gervaisi ticks infesting monitor lizards (Varanus begalensis) of Pakistan

Ticks pose significant health risks to both wildlife and humans due to their role as vectors for various pathogens. In this study, we investigated tick infestation patterns, tick-associated pathogens, and genetic relationships within the tick species Amblyomma gervaisi, focusing on its prevalence in monitor lizards (Varanus bengalensis) across different districts in Pakistan. We examined 85 monitor lizards and identified an overall mean intensity of 19.59 ticks per infested lizard and an overall mean abundance of 11.98 ticks per examined lizard. All collected ticks (n = 1019) were morphologically identified as A. gervaisi, including 387 males, 258 females, 353 nymphs, and 21 larvae. The highest tick prevalence was observed in the Buner district, followed by Torghar and Shangla, with the lowest prevalence in Chitral. Lizard captures primarily occurred from May to October, correlating with the period of higher tick infestations. Molecular analysis was conducted on tick DNA, revealing genetic similarities among A. gervaisi ticks based on 16S rDNA and ITS2 sequences. Notably, we found the absence of A. gervaisi ITS2 sequences in the NCBI GenBank, highlighting a gap in existing genetic data. Moreover, our study identified the presence of pathogenic microorganisms, including Ehrlichia sp., Candidatus Ehrlichia dumleri, Anaplasma sp., Francisella sp., Rickettsia sp., and Coxiella sp., in these ticks. BLAST analysis revealed significant similarities between these pathogenic sequences and known strains, emphasizing the potential role of these ticks as vectors for zoonotic diseases. Phylogenetic analyses based on nuclear ITS2 and mitochondrial 16S rDNA genes illustrated the genetic relationships of A. gervaisi ticks from Pakistan with other Amblyomma species, providing insights into their evolutionary history. These findings contribute to our understanding of tick infestation patterns, and tick-borne pathogens in monitor lizards, which has implications for wildlife health, zoonotic disease transmission, and future conservation efforts. Further research in this area is crucial for a comprehensive assessment of the risks associated with tick-borne diseases in both wildlife and humans.

Quantitative risk assessments of Salmonella spp. in domestic pork in China

Pork is one of the most commonly consumed meats, and its safety has always been a concern. Recently, safety incidents caused by chemical or biological contamination such as drug residues, heavy metals, and pathogenic microorganisms in pork have been reported, and the safety of pork is a cause for concern. Salmonella spp. is one of the important foodborne pathogens that threaten human health. Pork is a high-risk vector food for Salmonella spp. infection. The assessment of the safety risk of Salmonella spp. in pork is conducive to the prevention of related foodborne diseases. In this paper, risk assessment models for Salmonella spp. in meat were developed. The quantitative risk assessment model for Salmonella spp. based on the pork supply chain showed that the annual number of cases of salmonellosis due to pork consumption in China is approximately 27 per 10,000 males and 24 per 10,000 females. Sensitivity analysis showed that the main factors affecting the risk of Salmonella spp. in pork were the display temperature, display time, and Salmonella spp. contamination concentration in pork at the sale.

Recent advances in electrochemical aptasensors and genosensors for the detection of pathogens

In recent years, pathogenic microorganisms have caused significant mortality rates and antibiotic resistance and triggered exorbitant healthcare costs. These pathogens often have high transmission rates within human populations. Rapid diagnosis is crucial in controlling and reducing the spread of pathogenic infections. The diagnostic methods currently used against individuals infected with these pathogens include relying on outward symptoms, immunological-based and, some biomolecular ones, which mainly have limitations such as diagnostic errors, time-consuming processes, and high-cost platforms. Electrochemical aptasensors and genosensors have emerged as promising diagnostic tools for rapid, accurate, and cost-effective pathogen detection. These bio-electrochemical platforms have been optimized for diagnostic purposes by incorporating advanced materials (mainly nanomaterials), biomolecular technologies, and innovative designs. This review classifies electrochemical aptasensors and genosensors developed between 2021 and 2023 based on their use of different nanomaterials, such as gold-based, carbon-based, and others that employed other innovative assemblies without the use of nanomaterials. Inspecting the diagnostic features of various sensing platforms against pathogenic analytes can identify research gaps and open new avenues for exploration.

Bacteriophage Endolysin: A Powerful Weapon to Control Bacterial Biofilms

Bacterial biofilms are widespread in the environment, and bacteria in the biofilm are highly resistant to antibiotics and possess host immune defense mechanisms, which can lead to serious clinical and environmental health problems. The increasing problem of bacterial resistance caused by the irrational use of traditional antimicrobial drugs has prompted the search for better and novel antimicrobial substances. In this paper, we review the effects of phage endolysins, modified phage endolysins, and their combination with other substances on bacterial biofilms and provide an outlook on their practical applications. Phage endolysins can specifically and efficiently hydrolyze the cell walls of bacteria, causing bacterial lysis and death. Phage endolysins have shown superior bactericidal effects in vitro and in vivo, and no direct toxicity in humans has been reported to date. The properties of phage endolysins make them promising for the prevention and treatment of bacterial infections. Meanwhile, endolysins have been genetically engineered to exert a stronger scavenging effect on biological membranes when used in combination with antibiotics and drugs. Phage endolysins are powerful weapons for controlling bacterial biofilms.

A "safety cap" for improving hospital sanitation and reducing potential disease transmission

BACKGROUND

During endotracheal intubation, extubation, tracheotomy, and tracheotomy tube replacement, the splashed airway secretions of patients will increase the risk of transmission of SARS-CoV-2 and many other potential viral and bacterial diseases, such as influenza virus, adenovirus, respiratory syncytial virus, rhinovirus, Middle East respiratory coronavirus syndrome (MERS-CoV), Streptococcus pneumoniae, and Mycobacterium tuberculosis. Therefore, it is necessary to establish a barrier between patients and medical workers to reduce the risk of operators' infection with potentially pathogenic microorganisms.

METHODS

We designed a "safety cap" that can be connected to the opening of an endotracheal tube or tracheotomy tube to reduce the diffusion area of respiratory secretions during the process of endotracheal intubation, extubation and tracheotomy tube replace, so as to reduce the infection risk of medical workers.

RESULTS

Through a series of hydrodynamic simulation analysis and experiments, we demonstrated that the use of "safety cap" can substantially limit the spatter of airway secretions, so as to improve the hospital sanitation.

CONCLUSION

The "safety cap" can effectively limit the dissemination of patients' respiratory secretions, thus reducing the risk of potential diseases transmission and may have certain application prospects.

Characteristics of bacterial and fungal communities and their impact during cow manure and agroforestry biowaste co-composting

Microbial communities and environmental conditions are both of great importance for efficient utilization of agroforestry resources. Nevertheless, knowledge about the role of soluble nutrients and enzymatic properties, and their inner links with microbial communities remain limited. This is especially the case for the co-composting of agricultural and forestry biowaste. Here, we investigate the succession of key microbes during co-composting (sawdust + cow manure, SA; straw + cow manure, ST), employing amplicon sequencing, enzyme assays, and physicochemical analyses. N-fixing bacteria (Pseudomonas) and C-degrading fungi (Acaulium) have been identified as dominant taxa during such co-composting. Although eight antibiotic resistance genes were found to persist during composting, pathogenic microbes declined with composting time. NO₃^--N content was screened as a determinant structuring the bacterial and fungal communities, with importance also shown for C-degrading enzymes such as cellulose, laccase, and peroxidase activity. These results identify the key microbial taxa and their main interactive environmental factors, which are potentially valuable for the development of a mixed microbial inoculant to accelerate the maturation of agroforestry biowastes composting.

Value of digital PCR in the early diagnosis of sepsis: A systematic review and meta-analysis

BACKGROUND

We systematically assessed whether a digital polymerase chain reaction (PCR) could detect pathogenic microorganisms in patients with sepsis early and accurately.

METHODS

We searched the Cochrane Library, MEDLINE, Embase, CNKI, CBM, and Wanfang Data databases for eligible studies to compare the detection of pathogenic microorganisms in blood samples by digital PCR with the gold standard. The Quality Assessment of Diagnostic Accuracy Studies 2 was used to evaluate bias risk, and a random-effects meta-analysis approach was used for sensitivity and specificity calculations.

RESULTS

Among the eight articles, there were eight identified studies with a total of 1278 subjects. The pooled sensitivity of digital PCR was 94% (95% confidence interval [CI], 85%-98%), the specificity was 87% (95% CI, 76%-94%), the positive likelihood ratio was 7.3 (95% CI, 3.8-14.2), the negative likelihood ratio was 0.07 (95% CI, 0.03-0.17), the positive predictive value was 84.7%, the negative predictive value was 89.2%, the diagnostic odds ratio was 105 (95% CI, 37-303), and the area under the receiver operating characteristic curve was 0.97 (95% CI, 0.95-1.00). Digital PCR can shorten the detection time of pathogenic microorganisms in patients with sepsis.

CONCLUSIONS

Digital PCR can detect pathogenic microorganisms in patients with sepsis earlier than blood culture. Therefore, digital PCR can be used as a potential strategy for the detection of pathogenic microorganisms in patients with sepsis.

Access and benefit-sharing of the pathogenic microorganisms such as SARS-CoV-2

With the outbreak of coronavirus disease 2019 (COVID-19), it is essential to share pathogens and their data information safely, transparently, and timely. At the same time, it is also worth exploring how to share the benefits of using the provided pathogenic microorganisms fairly and equitably. There are some mechanisms for the management and sharing of pathogenic microbial resources in the world, such as the World Health Organization (WHO), the United States, the Europe, and China. This paper studies these mechanisms and puts forward "PICC" principles, including public welfare principle, interests principle, classified principle, and category principle, to strengthen cooperation, improve efficiency, and maintain biosafety.

The environment, epidemics, and human health

In this editorial piece, the Editors of the Virtual Special Issue (VSI) "The environment, epidemics, and human health" comment on the papers accepted for publication, which were selected after peer-reviewing among all those manuscripts submitted to the Special Issue. In view of the title of the VSI, it is clear that its aim goes beyond the COVID-19 pandemic, trying to explore relations among environmental aspects, any kind of epidemics, and human health. However, COVID-19 is still hitting as a global and current main issue, causing that manuscripts dealing with this disease and the SARS-CoV-2 virus are of high relevance in the whole set of research papers published.

Inhibition of microbial pathogens in farmed fish

Aquaculture, also known as aqua farming, is defined as farming fish, crustaceans, mollusks, aquatic plants, algae, and other marine organisms. It includes cultivating fresh- and saltwater populations under controlled conditions compared to commercial fishing or wild fish harvesting. Worldwide, carp, salmon, tilapia, and catfish are the most common fish species used in fish farming in descending order. Disinfectants prevent and/or treat different infections in aquatic animals. The current review indicates the uses of different disinfectants against some important pathogens in aquaculture, with particular reference to tilapia (Oreochromis niloticus) farming. A single review cannot cover all aspects of disinfection throughout aquaculture, so the procedures and principles of disinfection in tilapia farming/aquaculture have been chosen for illustration purposes.

In-situ chemical attenuation of pharmaceutically active compounds using CaO2: Influencing factors, mechanistic modeling, and cooperative inactivation of water-borne microbial pathogens

Water polluted by pharmaceutically active compounds (PhACs) and water-borne pathogens urgently need to develop eco-friendly and advanced water treatment techniques. This paper evaluates the potential of using calcium peroxide (CaO₂), a safe and biocompatible oxidant both PhACs (thiamphenicol, florfenicol, carbamazepine, phenobarbital, and primidone) and pathogens (Escherichia coli, Staphylococcus aureus) in water. This paper evaluates the potential of using calcium peroxide (CaO₂) as a safe and biocompatible oxidant to remove both PhACs (thiamphenicol, florfenicol, carbamazepine, phenobarbital, and primidone) and pathogens (Escherichia coli, Staphylococcus aureus) in water. The increased CaO₂ dosage increased efficiencies of PhACs attenuation and pathogens inactivation, and both exhibited pseudo-first-order degradation kinetics (R² > 0.90). PhACs attenuation were mainly via oxidization (H₂O₂, •OH/O^•-, and O₂^•-) and alkaline hydrolysis (OH^-) from CaO₂. Moreover, concentrations of these reactive species and their contributions to PhACs attenuation were quantified, and mechanistic model was established and validated. Besides, possible transformation pathways of target PhACs except primidone were proposed. As for pathogen indicators, the suitable inactivation dosage of CaO₂ was 0.1 g L^-1. The oxidability (18-64%) and alkalinity (82-36%) generated from CaO₂ played vital roles in pathogen inactivation. In addition, CaO₂ at 0.01-0.1 g L^-1 can be applied in remediation of SW contaminated by PhACs and pathogenic bacteria, which can degrade target PhACs with efficiencies of 21-100% under 0.01 g L^-1 CaO₂, and inactivate 100% of test bacteria under 0.1 g L^-1 CaO₂. In short, capability of CaO₂ to remove target PhACs and microbial pathogens reveals its potential to be used as a representative technology for the advanced treatment of waters contaminated by organic compounds and microbial pathogens.

Machine learning to predict dynamic changes of pathogenic Vibrio spp. abundance on microplastics in marine environment

Microplastics are widely found in the marine environment. Recent studies have shown that pathogenic microorganisms can hitchhike on microplastics, which might act as a vector for the spread of pathogens. Vibrio spp. are known to be pathogenic to humans and can cause serious foodborne diseases. In this study, using datasets from an estuary and a mariculture zone in China, five machine learning models were established to predict the relative abundance of Vibrio spp. on microplastics. The results showed that deep neural network (DNN) model and RandomForest algorithm achieved the best predictive performance. Different data sources, data sampling, and processing methods had a little impact on the prediction performance of DNN and RandomForest models. SHapley Additive exPlanations (SHAP) indicated that salinity and temperature are the primary factors affecting the relative abundance of Vibrio spp. The prediction performances of the five machine learning models were further improved by feature selection, providing information to support future experimental research. The results of this study could help establish a long-term and dynamic monitoring system for the relative abundance of Vibrio spp. on microplastics in response to environmental factors as well as provide useful information for assessing the potential health impacts of microplastics on marine ecology and humans.

GBDR: a Bayesian model for precise prediction of pathogenic microorganisms using 16S rRNA gene sequences

BACKGROUND

Recent evidences have suggested that human microorganisms participate in important biological activities in the human body. The dysfunction of host-microbiota interactions could lead to complex human disorders. The knowledge on host-microbiota interactions can provide valuable insights into understanding the pathological mechanism of diseases. However, it is time-consuming and costly to identify the disorder-specific microbes from the biological "haystack" merely by routine wet-lab experiments. With the developments in next-generation sequencing and omics-based trials, it is imperative to develop computational prediction models for predicting microbe-disease associations on a large scale.

RESULTS

Based on the known microbe-disease associations derived from the Human Microbe-Disease Association Database (HMDAD), the proposed model shows reliable performance with high values of the area under ROC curve (AUC) of 0.9456 and 0.8866 in leave-one-out cross validations and five-fold cross validations, respectively. In case studies of colorectal carcinoma, 80% out of the top-20 predicted microbes have been experimentally confirmed via published literatures.

CONCLUSION

Based on the assumption that functionally similar microbes tend to share the similar interaction patterns with human diseases, we here propose a group based computational model of Bayesian disease-oriented ranking to prioritize the most potential microbes associating with various human diseases. Based on the sequence information of genes, two computational approaches (BLAST+ and MEGA 7) are leveraged to measure the microbe-microbe similarity from different perspectives. The disease-disease similarity is calculated by capturing the hierarchy information from the Medical Subject Headings (MeSH) data. The experimental results illustrate the accuracy and effectiveness of the proposed model. This work is expected to facilitate the characterization and identification of promising microbial biomarkers.

Microbiological quality analysis of inoculants based on Bradyrhizobium spp. and Azospirillum brasilense produced "on farm" reveals high contamination with non-target microorganisms

The use of inoculants carrying diazotrophic and other plant growth-promoting bacteria plays an essential role in the Brazilian agriculture, with a growing use of microorganism-based bioproducts. However, in the last few years, some farmers have multiplied microorganisms in the farm, known as "on farm" production, including inoculants of Bradyrhizobium spp. for soybean (Glycine max L. Merrill.) and Azospirillum brasilense for corn (Zea mays L.) or co-inoculation in soybean. The objective was to assess the microbiological quality of such inoculants concerning the target microorganisms and contaminants. In the laboratory, 18 samples taken in five states were serial diluted and spread on culture media for obtaining pure and morphologically distinct colonies of bacteria, totaling 85 isolates. Molecular analysis based on partial sequencing of the 16S rRNA gene revealed 25 genera of which 44% harbor species potentially pathogenic to humans; only one of the isolates was identified as Azospirillum brasilense, whereas no isolate was identified as Bradyrhizobium. Among 34 isolates belonging to genera harboring species potentially pathogenic to humans, 12 had no resistance to antibiotics, six presented intrinsic resistance, and 18 presented non-intrinsic resistance to at least one antibiotic. One of the samples analyzed with a shotgun-based metagenomics approach to check for the microbial diversity showed several genera of microorganisms, mainly Acetobacter (~ 32% of sequences) but not the target microorganism. The samples of inoculants produced on farm were highly contaminated with non-target microorganisms, some of them carrying multiple resistances to antibiotics.

SARS-CoV-2 and other pathogens in municipal wastewater, landfill leachate, and solid waste: A review about virus surveillance, infectivity, and inactivation

This review discusses the techniques available for detecting and inactivating of pathogens in municipal wastewater, landfill leachate, and solid waste. In view of the current COVID-19 pandemic, SARS-CoV-2 is being given special attention, with a thorough examination of all possible transmission pathways linked to the selected waste matrices. Despite the lack of works focused on landfill leachate, a systematic review method, based on cluster analysis, allows to analyze the available papers devoted to sewage sludge and wastewater, allowing to focalize the work on technologies able to detect and treat pathogens. In this work, great attention is also devoted to infectivity and transmission mechanisms of SARS-CoV-2. Moreover, the literature analysis shows that sewage sludge and landfill leachate seem to have a remote chance to act as a virus transmission route (pollution-to-human transmission) due to improper collection and treatment of municipal wastewater and solid waste. However due to the incertitude about virus infectivity, these possibilities cannot be excluded and need further investigation. As a conclusion, this paper shows that additional research is required not only on the coronavirus-specific disinfection, but also the regular surveillance or monitoring of viral loads in sewage sludge, wastewater, and landfill leachate. The disinfection strategies need to be optimized in terms of dosage and potential adverse impacts like antimicrobial resistance, among many other factors. Finally, the presence of SARS-CoV-2 and other pathogenic microorganisms in sewage sludge, wastewater, and landfill leachate can hamper the possibility to ensure safe water and public health in economically marginalized countries and hinder the realization of the United Nations' sustainable development goals (SDGs).

The characteristics of multi-substrates (low and high C/N) anaerobic digestion: focus on energy recovery and the succession of methanogenic pathway

Anaerobic digestion of common rural wastes (human feces (HF), food waste (FW) and lawn grass (LG)) were studied considering the specific methane yield, process parameters and microbial characteristics (mainly microbial community and pathogenic bacteria). The results showed that co-digestion of multiple substrates obtained high digestion performance when the total solid (TS) was 4%. The optimal co-digestion ratio of HF, FW, and LG was 33-56%, 21-38% and 20-40%, respectively. The digestion system containing HF underwent ammonia inhibition, which leads to the succession of the methanogenesis pathway from the acetoclastic pathway to the hydrogenotrophic pathway. Simultaneously, the dominant methanogenic archaea changed from Methanosaeta to Methanobacterium and Methanosarcina. Co-digestion reduced Salmonella's absolute concentration. The recovered energy and nitrogen could meet 52-109 % energy demand of rural community and all nitrogen demand in lawn fertilization, respectively. The main rural organic wastes could be recycled by anaerobic digestion, considering the flexibility of substrate ratio.

Inactivation and risk control of pathogenic microorganisms in municipal sludge treatment: A review

The rapid global spread of coronavirus disease 2019 (COVID-19) has promoted concern over human pathogens and their significant threats to public health security. The monitoring and control of human pathogens in public sanitation and health facilities are of great importance. Excessive sludge is an inevitable byproduct of sewage that contains human and animal feces in wastewater treatment plants (WWTPs). It is an important sink of different pollutants and pathogens, and the proper treatment and disposal of sludge are important to minimize potential risks to the environment and public health. However, there is a lack of comprehensive analysis of the diversity, exposure risks, assessment methods and inactivation techniques of pathogenic microorganisms in sludge. Based on this consideration, this review summarizes the control performance of pathogenic microorganisms such as enterovirus, Salmonella spp., and Escherichia coli by different sludge treatment technologies, including composting, anaerobic digestion, aerobic digestion, and microwave irradiation, and the mechanisms of pathogenic microorganism inactivation in sludge treatment processes are discussed. Additionally, this study reviews the diversity, detection methods, and exposure risks of pathogenic microorganisms in sludge. This review advances the quantitative assessment of pathogenic microorganism risks involved in sludge reuse and is practically valuable to optimize the treatment and disposal of sludge for pathogenic microorganism control.

How to study SARS-CoV-2 in soils?

Wastewater based epidemiology is increasingly being considered as a potentially useful tool for early warning about eventual new COVID-19 outbreaks. In addition, some authors are investigating on the detection and quantification of SARS-CoV-2 in sewage sludge. However, no paper has been published up to date indicating how this virus could be quantified in soil samples. In view of that, we review available data searching for methodological approaches that could guide on the quantification of SARS-CoV-2 (and even other pathogenic microorganisms) in soils.

Detection of Salmonella by the 3M Molecular Detection Assays: MDS® Method

Developed by 3M Company, 3M ™ Molecular Detection Assays-3M MDS-enable detection of Salmonella from advanced isothermal DNA amplification and bioluminescence detection technology. It can be used for a wide variety of products, including poultry, eggs, pet foods, and environmental samples, and results are obtained within about 24 h. In this chapter, all steps of the 3M MDS™ method for detection of Salmonella are described and detailed.

Evaluation of Chemical and Microbiological Contaminants in Fresh Fruits and Vegetables from Peasant Markets in Cundinamarca, Colombia

ABSTRACT

In this study, chemical and microbiological contaminants were detected in fresh fruits and vegetables in peasant markets in the Department of Cundinamarca to assess food safety. At least one pesticide was detected in 63% of the samples evaluated (n = 100, including fruits and vegetables), and in 41% of these, pesticides exceeded the maximum residue limit. Within the pesticides found, 60% do not use a registry from the Instituto Colombiano Agropecuario to be applied on the crops where they were detected and are included in the toxicological categories "highly toxic" (category IB) and "moderately toxic" (category II). Heavy metals were found in 45% of the samples, with cadmium (38%) and lead (14%) being the most frequent. The pathogenic microorganisms Escherichia coli O157:H7, Listeria monocytogenes, Salmonella, and Campylobacter sp. were detected in 4, 2, 1, and 0% of the samples, respectively. Factors concerning integrated crop management, contaminated inputs with chemicals and microorganisms, and the lack of hygiene in the postharvest stage favor the presence of pesticide residues, heavy metals, and the appearance of pathogenic microorganisms. The results suggest the need to strengthen the implementation of integrated management strategies that guarantee the safety of fresh fruits and vegetables in the country.

HIGHLIGHTS

An approach to the photocatalytic mechanism in the TiO2-nanomaterials microorganism interface for the control of infectious processes

The approach of this timely review considers the current literature that is focused on the interface nanostructure/cell-wall microorganism to understand the annihilation mechanism. Morphological studies use optical and electronic microscopes to determine the physical damage on the cell-wall and the possible cell lysis that confirms the viability and microorganism death. The key parameters of the tailoring the surface of the photoactive nanostructures such as the metal functionalization with bacteriostatic properties, hydrophilicity, textural porosity, morphology and the formation of heterojunction systems, can achieve the effective eradication of the microorganisms under natural conditions, ranging from practical to applications in environment, agriculture, and so on. However, to our knowledge, a comprehensive review of the microorganism/nanomaterial interface approach has rarely been conducted. The final remarks point the ideal photocatalytic way for the effective prevention/eradication of microorganisms, considering the resistance that the microorganism could develop without the appropriate regulatory aspects for human and ecosystem safety.

An approach to the photocatalytic mechanism in the TiO2-nanomaterials microorganism interface for the control of infectious processes

The approach of this timely review considers the current literature that is focused on the interface nanostructure/cell-wall microorganism to understand the annihilation mechanism. Morphological studies use optical and electronic microscopes to determine the physical damage on the cell-wall and the possible cell lysis that confirms the viability and microorganism death. The key parameters of the tailoring the surface of the photoactive nanostructures such as the metal functionalization with bacteriostatic properties, hydrophilicity, textural porosity, morphology and the formation of heterojunction systems, can achieve the effective eradication of the microorganisms under natural conditions, ranging from practical to applications in environment, agriculture, and so on. However, to our knowledge, a comprehensive review of the microorganism/nanomaterial interface approach has rarely been conducted. The final remarks point the ideal photocatalytic way for the effective prevention/eradication of microorganisms, considering the resistance that the microorganism could develop without the appropriate regulatory aspects for human and ecosystem safety.

Microbiological Reduction Strategies of Irrigation Water for Fresh Produce

ABSTRACT

Irrigation water can be a source of pathogenic contamination of fresh produce. Controlling the quality of the water used during primary production is important to ensure food safety and protect human health. Several measures to control the microbiological quality of irrigation water are available for growers, including preventative and mitigation strategies. However, clear guidance for growers on which strategies could be used to reduce microbiological contamination is needed. This study evaluates pathogenic microorganisms of concern in fresh produce and water, the microbiological criteria of water intended for agricultural purposes, and the preventative and mitigative microbial reduction strategies. This article provides suggestions for control measures that growers can take during primary production to reduce foodborne pathogenic contamination coming from irrigation water. Results show that controlling the water source, regime, and timing of irrigation may help to reduce the potential exposure of fresh produce to contamination. Moreover, mitigation strategies like electrolysis, ozone, UV, and photocatalysts hold promise either as a single treatment, with pretreatments that remove suspended material, or as combined treatments with another chemical or physical treatment(s). Based on the literature data, a decision tree was developed for growers, which describes preventative and mitigation strategies for irrigation-water disinfection based on the fecal coliform load of the irrigation water and the water turbidity. It helps guide growers when trying to evaluate possible control measures given the quality of the irrigation water available. Overall, the strategies available to control irrigation water used for fresh produce should be evaluated on a case-by-case basis because one strategy or technology does not apply to all scenarios.

HIGHLIGHTS

The role of reactive oxygen species in the biological activity of antimicrobial agents: An updated mini review

Antimicrobial resistance remains a serious problem that results in high mortality and increased healthcare costs globally. One of the major issues is that resistant pathogens decrease the efficacy of conventional antimicrobials. Accordingly, development of novel antimicrobial agents and therapeutic strategies is urgently needed to overcome the challenge of antimicrobial resistance. A potential strategy is to kill pathogenic microorganisms via the formation of reactive oxygen species (ROS). ROS are defined as a number of highly reactive molecules that comprise molecular oxygen (O₂), superoxide anion (O₂^•-), hydrogen peroxide (H₂O₂) and hydroxyl radicals (^•OH). ROS exhibit antimicrobial actions against a broad range of pathogens through the induction of oxidative stress, which is an imbalance between ROS and the ability of the antioxidant defence system to detoxify ROS. ROS-dependent oxidative stress can damage cellular macromolecules, including DNA, lipids and proteins. This article reviews the antimicrobial action of ROS, challenges to ROS hypothesis, work to solidify ROS-mediated antimicrobial lethality hypothesis, recent developments in antimicrobial agents using ROS as an antimicrobial strategy, safety concerns related to ROS, and future directions in ROS research.

Design of a bioaugmented multistage biofilter for accelerated municipal wastewater treatment and deactivation of pathogenic microorganisms

Biological treatment of municipal wastewater for reuse in irrigation is highly required, especially with the current global financial and water shortage crises. Bioaugmentation is a simple and cost-effective technology which could be a useful tool in alleviating this challenge. Thus, this study aimed to enhance the biological treatment of municipal wastewater using a bioaugmented substance supplemented in a three-stages bio-filter consisting of a sedimentation step followed by gravel biofiltration and then sand biofiltration at a laboratory scale. Also, a toxicity assay, the antimicrobial effect of the bioaugmented substance against pathogenic microorganisms, and identification of the synergistic effect of the bacterial consortium involved in the bioaugmented substance were studied. The bioaugmented substance was nontoxic and had an antimicrobial effect against the tested potentially pathogenic microorganisms (Escherichia coli, Pseudomonas aeruginosa, Listeria monocytogenes, Staphylococcus aureus, and Candida albicans). The minimum effective concentration of the bioaugmented substance for organic, inorganic and microbial pollutants removal from high strength wastewater was 2.5 ppm with a contact time of 6-8 h. The removal efficiencies of H₂S, COD, BOD₅, total solids (TS), total dissolved solids, total suspended solids, ammonia, nitrate, phosphorus, and oil and grease reached 85, 93.4, 83.5, 37, 49.2, 93.4, 100, 55.7, 76.6 and 76.6%, respectively in the treated effluent after sand biofiltration. The physicochemical parameters of the treated wastewater effluent were below the Egyptian recommended limits (Law 84/1984) for use in irrigation. However, COD and BOD values were 90.33 and 38.46 mgO₂/L, respectively, and were still above the regulations (COD ≤60 and BOD ≤20). The high fecal coliforms count in the wastewater influent (8.4 × 10⁸ MPN-index/100 mL) were 95.1% removed after the sedimentation stage, and 99.99% removal was achieved after gravel and sand biofiltration. Thus, this study successfully designed a bioaugmented multistage biofiltration system for the effective removal of pollutants from wastewater, especially in resource-limited areas.

Antimicrobial and antibiofilm activities of prenylated flavanones from Macaranga tanarius

BACKGROUND

The emergence of antibiotic resistant microorganisms presents a worldwide problem that requires novel antibiotic and non-antibiotic strategies, and biofilm formation is a mechanism of drug resistance utilized by diverse microorganisms. The majority of microorganisms live in biofilms that help their survival against starvation, antimicrobial agents, and immunological defense systems. Therefore, it is important novel compounds be identified that inhibit biofilm formation and cell survival without drug resistance.

STUDY DESIGN

In this study, the antimicrobial and antibiofilm activities of five prenylated flavanones (Okinawan propolins) isolated from fruits of Macaranga tanarius (L.) were investigated against 14 microorganisms including 10 pathogens.

RESULTS

Of these five propolins, propolin D at 5-10 µg/ml significantly inhibited biofilm formation by three Staphylococcus aureus strains, a Staphylococcus epidermidis strain, and a Candida albicans with MICs from 10 to 50 µg/ml, and in C. albicans, propolin D was found to inhibit biofilm formation by reducing cell aggregation and downregulated the expressions of hypha/biofilm-related genes including ECE1 and HWP1. Interestingly, at sub-MIC concentrations (10-50 µg/ml), propolin D significantly inhibited biofilm formation by enterohemorrhagic E. coli O157:H7, uropathogenic E. coli O6:H1, and Acinetobacter baumannii without affecting planktonic cell growth, but did not inhibit biofilm formation by a commensal E. coli K-12 strain, three probiotic Lactobacillus plantarum strains, or two Pseudomonas aeruginosa strains. And, propolin D reduced fimbriae production by E. coli O157:H7 and repressed gene expression of curli fimbriae genes (csgA and csgB). Also, propolin D was minimally toxic in a Caenorhabditis elegans nematode model.

CONCLUSION

These findings show that prenylated flavanones, especially propolin D from Macaranga tanarius (Okinawan propolis), should be considered potential candidates for the development of non-toxic antibacterial and antifungal agents against persistent microorganisms.

The synthesis of novel chromogenic enzyme substrates for detection of bacterial glycosidases and their applications in diagnostic microbiology

The preparation and evaluation of chromogenic substrates for detecting bacterial glycosidase enzymes is reported. These substrates are monoglycoside derivatives of the metal chelators catechol, 2,3-dihydroxynaphthalene (DHN) and 6,7-dibromo-2,3-dihydroxynaphthalene (6,7-dibromo-DHN). When hydrolysed by appropriate bacterial enzymes these substrates produced coloured chelates in the presence of ammonium iron(III) citrate, thus enabling bacterial detection. A β-d-riboside of DHN and a β-d-glucuronide derivative of 6,7-dibromo-DHN were particularly effective for the detection of S. aureus and E. coli respectively.

Bird feathers as potential sources of pathogenic microorganisms: a new look at old diseases

This article describes methods of treatment for avian zoonoses, modern antibiotic therapy and drug resistance of selected pathogens, which pose a threat to the population’s health. A tabular form has been used to present the current data from the European Union from 2011 to 2017 regarding human morbidity and mortality and the costs incurred by national health systems for the treatment of zoonoses occurring in humans and animals. Moreover, the paper includes descriptions of selected diseases, which indirectly affect birds. Scientists can obtain information regarding the occurrence of particular diseases, their aetiology, epidemiology, incubation period and symptoms caused by dangerous microorganisms and parasites. This information should be of particular interest for people who have frequent contact with birds, such as ornithologists, as well as veterinarians, farm staff, owners of accompanying animals and zoological workers. This paper presents a review used for identification and genetic characterization of bacterial strains isolated from a variety of environmental sources, e.g., bird feathers along with their practical application. We describe the bacterial, viral and fungal serotypes present on avian feathers after the slaughter process. This review also enables us to effectively identify several of the early stages of infectious diseases from heterogeneous avian research material.

Chitosan and chitooligosaccharides from shrimp shell waste: characterization, antimicrobial and shelf life extension in bread

Chitosan and chitooligosaccharides were extracted from white-leg shrimp shells by chemical treatment. Low molecular weight (13 kDa) and a high degree of deacetylation (54.83%) in chitooligosaccharides led to high water solubility compared to chitosan. Antimicrobial assays indicated that chitosan and chitooligosaccharides exhibited marked inhibitory activity against food-borne pathogenics, spoilage bacterial, and fungal strains tested. However, chitooligosaccharides revealed greater inhibitory effects than chitosan on tested microorganisms. The substitution of flour by chitosan or chitooligosaccharides in bread formulation (1 g/100 g total weight basis) showed antimicrobial effects against Bacillus cereus and Rhizopus sp. growth. Also, the fruity odor in bread containing chitosan or chitooligosaccharides was delayed. Interestingly, the bread containing chitooligosaccharides showed a stronger inhibitory effect against B. cereus and Rhizopus sp. compared to bread containing chitosan and control, where B. cereus and Rhizopus sp. were observed growing on the surface of bread after 4 days of incubation at 30 °C.

An Overview of Occupational Risks From Climate Change

Changes in atmosphere and temperature are affecting multiple environmental indicators from extreme heat events to global air quality. Workers will be uniquely affected by climate change, and the occupational impacts of major shifts in atmospheric and weather conditions need greater attention. Climate change-related exposures most likely to differentially affect workers in the USA and globally include heat, ozone, polycyclic aromatic hydrocarbons, other chemicals, pathogenic microorganisms, vector-borne diseases, violence, and wildfires. Epidemiologic evidence documents a U-, J-, or V-shaped relationship between temperature and mortality. Whereas heat-related morbidity and mortality risks are most evident in agriculture, many other outdoor occupational sectors are also at risk, including construction, transportation, landscaping, firefighting, and other emergency response operations. The toxicity of chemicals change under hyperthermic conditions, particularly for pesticides and ozone. Combined with climate-related changes in chemical transport and distribution, these interactions represent unique health risks specifically to workers. Links between heat and interpersonal conflict including violence require attention because they pose threats to the safety of emergency medicine, peacekeeping and humanitarian relief, and public safety professionals. Recommendations for anticipating how US workers will be most susceptible to climate change include formal monitoring systems for agricultural workers; modeling scenarios focusing on occupational impacts of extreme climate events including floods, wildfires, and chemical spills; and national research agenda setting focusing on control and mitigation of occupational susceptibility to climate change.

Use of an Ex Vivo Porcine Mucosal Model to Study Superantigen Penetration

In vitro perfusion studies are frequently used to determine the penetration of compounds through skin and mucosa. Porcine tissue has been shown to be an excellent model for human tissue in terms of structure, function, and reactivity. We describe the use of porcine tissue ex-vivo in a continuous flow perfusion system to study the behavior of superantigens in this model.

Post-industrial river water quality-Fit for bathing again?

For the Ruhr River, bathing has been prohibited for decades. However, along with significant improvements of the hygienic water quality, there is an increasing demand of using the river for recreational purposes, in particular for bathing. In the "Safe Ruhr" interdisciplinary research project, demands, options and chances for lifting the bathing ban for the Ruhr River were investigated. As being the prominent reason for persisting recreational restrictions, microbiological water quality was in the focus of interest. Not only the faecal indicator organisms (FIOs) as required by the European Bathing Water Directive were considered, but also pathogens such as Salmonella, Pseudomonas aeruginosa, Legionella pneumophila, Campylobacter, Leptospira, enteroviruses and protozoan parasites. In this introductory paper, we firstly relate current recreational desires to historical experiences of river bathing. After recapitulating relevant microbial river contamination sources (predominantly sewage treatment plants, combined sewer overflows, and surface runoffs), we review existing knowledge about the relationships of FIOs and pathogens in rivers designated for recreational purposes, and then trace the evolution, rationale and validity of recreational freshwater quality criteria which are, despite obvious uncertainties, mostly relying on the FIO paradigm. In particular, the representativeness of FIOs is critically discussed. The working programme of Safe Ruhr, aiming at initiating and facilitating a process towards legalisation of Ruhr River bathing, is outlined. Sources of contamination can be technically handled which leaves the actual measures to political decisions. As contaminations are transient, only occasionally exceeding legal limits, a flexible bathing site management, warning bathers of non-safe situations, may amend technical interventions and offer innovative solutions. As a result, a situation-adapted system for lifting of the bathing ban for Ruhr River appears realistic.

Using microbiological tracers to assess the impact of winter land use restrictions on the quality of stream headwaters in a small catchment

Diverse land use activities can elevate risk of microbiological contamination entering stream headwaters. Spatially distributed water quality monitoring carried out across a 17 km(2) agricultural catchment aimed to characterize microbiological contamination reaching surface water and investigate whether winter agricultural land use restrictions proved effective in addressing water quality degradation. Combined flow and concentration data revealed no significant difference in fecal indicator organism (FIO) fluxes in base flow samples collected during the open and prohibited periods for spreading organic fertilizer, while relative concentrations of Escherichia coli, fecal streptococci and sulfite reducing bacteria indicated consistently fresh fecal pollution reached aquatic receptors during both periods. Microbial source tracking, employing Bacteroides 16S rRNA gene markers, demonstrated a dominance of bovine fecal waste in river water samples upstream of a wastewater treatment plant discharge during open periods. This contrasted with responses during prohibited periods where human-derived signatures dominated. Differences in microbiological signature, when viewed with hydrological data, suggested that increasing groundwater levels restricted vertical infiltration of effluent from on-site wastewater treatment systems and diverted it to drains and surface water. Study results reflect seasonality of contaminant inputs, while suggesting winter land use restrictions can be effective in limiting impacts of agricultural wastes to base flow water quality.

Sewage sludge, compost and other representative organic wastes as agricultural soil amendments: Benefits versus limiting factors

Nine different samples of sewage sludges, composts and other representative organic wastes, with potential interest to be used as agricultural soil amendments, were characterized: municipal sewage sludge (SS1 and SS2), agro industrial sludge (AIS), municipal slaughterhouse sludge (MSS), mixed municipal solid waste compost (MMSWC), agricultural wastes compost (AWC), compost produced from agricultural wastes and sewage sludge (AWSSC), pig slurry digestate (PSD) and paper mill wastes (PMW). The characterization was made considering their: (i) physicochemical parameters, (ii) total and bioavailable heavy metals (Cd, Cr, Cu, Ni, Pb, Zn and Hg), (iii) organic contaminants, (iv) pathogenic microorganisms and (v) stability and phytotoxicity indicators. All the sludges, municipal or other, comply with the requirements of the legislation regarding the possibility of their application to agricultural soil (with the exception of SS2, due to its pathogenic microorganisms content), with a content of organic matter and nutrients that make them interesting to be applied to soil. The composts presented, in general, some constraints regarding their application to soil, and their impairment was due to the existence of heavy metal concentrations exceeding the proposed limit of the draft European legislation. As a consequence, with the exception of AWSSC, most compost samples were not able to meet these quality criteria, which are more conservative for compost than for sewage sludge. From the results, the composting of sewage sludge is recommended as a way to turn a less stabilized waste into a material that is no longer classified as a waste and, judging by the results of this work, with lower heavy metal content than the other composted materials, and without sanitation problems.

Methods for the discovery of emerging pathogens

Recently, there has been a steady increase in the number of recognized pathogenic microorganisms, specifically bacteria. The development of genetic technologies, MALDI-TOF mass spectrometry and new culturing techniques has significantly widened the repertoire of known microorganisms and therefore pathogenic microorganisms. The repertoire of infectious agents has been studied in various environments including water, soil, pets, livestock, wildlife and arthropods. Using different methods, many known pathogens can be identified in these samples; therefore, the impact of emergent pathogens on humans can be examined and novel pathogens can be identified. In this special issue, we discuss the identification of emerging pathogens in the environment and animals.

High resolution melting (HRM) analysis of DNA--its role and potential in food analysis

DNA based methods play an increasing role in food safety control and food adulteration detection. Recent papers show that high resolution melting (HRM) analysis is an interesting approach. It involves amplification of the target of interest in the presence of a saturation dye by the polymerase chain reaction (PCR) and subsequent melting of the amplicons by gradually increasing the temperature. Since the melting profile depends on the GC content, length, sequence and strand complementarity of the product, HRM analysis is highly suitable for the detection of single-base variants and small insertions or deletions. The review gives an introduction into HRM analysis, covers important aspects in the development of an HRM analysis method and describes how HRM data are analysed and interpreted. Then we discuss the potential of HRM analysis based methods in food analysis, i.e. for the identification of closely related species and cultivars and the identification of pathogenic microorganisms.

Preliminary safety evaluation of photodynamic therapy for blood purification: an animal study

Photodynamic therapy (PDT) has been shown to inactivate blood-borne pathogenic microorganisms in vitro. The method may be used to purify blood in the body, kill pathogenic microorganisms, and treat difficult diseases. Our aim was to investigate the safety of photodynamic blood purification (PBP) therapy using an in vivo blood circulation experiment in an animal model. Twenty-four New Zealand rabbits were used as experimental subjects; 12 received PDT and 12 served as negative controls. Extracorporeal blood bypass was established using the femoral artery and vein. A sterile disposable irradiation chamber was connected in the bypass pathway. Hematoporphyrin monomethyl ether was injected intravenously as a photosensitizer with an initial bolus of 3.7 mg, followed by a continuous infusion at 24 mg/h during PDT administration. Five minutes after initial injection, a laser beam was vertically focused on the irradiation chamber side wall, with a 9.5 cm(2) spot area, 1 h exposure time, and 20 mW/cm(2) power density. Six animals received a single PDT application, and six received PDT every other day for three applications. The 12 control group animals underwent extracorporeal blood circulation but did not receive the photosensitizer or light treatment. Blood samples were taken 20 min, 1 day, 4 days, and 7 days after PDT treatment for analysis of cell counts, coagulation, liver and renal function, and other biochemical changes. On the 7th day, animals were sacrificed, and parenchymal organs were evaluated for morphological changes. There were no significant differences in white blood cells, red blood cells, or destroyingplatelets after PDT compared with the control group. There was a little significant difference in alanine aminotransferase, aspartate aminotransferase, alkaline phosphatase, γ-glutamyl transpeptidase, uric acid, blood urea nitrogen, and creatinine in the PDT group compared with the control group, except at individual time points. We found no significant damage in the heart, liver, spleen, lungs, kidneys, or other organs after PDT. This short-duration, fixed-strength PBP method did not cause changes in blood parameters or in the structure or function of major organs in an animal model. These findings suggest that PBP is safe in vivo and has potential as a new therapy for inactivating blood-borne microorganisms.

Antimicrobial activity of saquayamycins produced by Streptomyces spp. PAL114 isolated from a Saharan soil

A new strain of actinomycete designated PAL114, producing antimicrobial compounds, was isolated from a Saharan soil in Ghardaïa, Algeria. Morphological and chemical studies showed that this strain belonged to the genus Streptomyces. Two bioactive compounds, named P41A and P41B, were extracted by dichloromethane from the cell-free supernatant broth of strain PAL114 and were purified by HPLC. Minimum inhibitory concentrations of the pure antibiotics were determined against yeasts, filamentous fungi and bacteria, most of which are pathogenic or toxigenic for human and multiresistant to antibiotics. The strongest activities were observed against Candida albicans M3 and Bacillus subtilis ATCC 6633. The chemical structures of the compounds were determined by spectroscopic analysis of UV-visible and 1H and 13C NMR spectra and spectrometric analysis of mass spectrum. The compounds P41A and P41B were identified as saquayamycins A and C, respectively. These compounds belong to the aquayamycin-group antibiotics, which are known in the literature for their anticancer and antibacterial activities.

Pathogenic Microorganisms Associated with Fresh Produce

The presence of numerous genera of spoilage bacteria, yeasts and molds, and an occasional pathogen on fresh produce has been recognized for many years. Several outbreaks of human gastroenteritis have been linked to the consumption of contaminated fresh vegetables and, to a lesser extent, fruits. Salads containing raw vegetables have been identified as vehicles of traveler's diarrhea, an illness sometimes experienced by visitors to developing countries. Enterotoxigenic Escherichia coli is the most common cause of this illness. Enterohemorrhagic E. coli , specifically serotype O157:H7, has been implicated as the causative agent in an outbreak of gastroenteritis resulting from the consumption of cantaloupes. Outbreaks of salmonellosis in humans have been attributed to consumption of contaminated tomatoes, mustard cress, bean sprouts, cantaloupe, and watermelon. An onion-associated outbreak of Shigella flexneri gastroenteritis has recently been reported in the United States. Outbreaks of human listeriosis have been epidemiologically linked to the consumption of fresh cabbage and lettuce. Gastrointestinal illness caused by the consumption of raw vegetable seed sprouts contaminated by Bacillus cereus has been documented. The ability of Aeromonas hydrophila and Aeromonas sobria to produce several virulence factors has been documented and their fairly common occurrence in water raises concern over public health risks that may be associated with the consumption of salad vegetables, although their role as agents in foodborne illness has not been fully confirmed. Viruses are not likely to grow on contaminated vegetables and fruits but can survive long enough to cause life-threatening illness in humans. An increased per capita consumption of fresh and lightly processed produce in the United States and other countries, coupled with an increase in importation of produce to these countries from regions where standards for growing and handling produce may be compromised, has resulted in heightened interest in outbreaks of human gastroenteritis that may be attributed to contaminated fresh produce, particularly salad vegetables. Likewise methods of handling, processing, packaging, and distribution of fresh produce on a regional or local scale within countries are receiving attention in terms of identifying and controlling microbiological hazards. Hazard analysis critical control point (HACCP) programs are being developed in an effort to minimize the risk of illness associated with consumption of fresh produce. Examples of pathogenic microorganisms associated with fresh produce as well as procedures that can be used to reduce their incidence at the point of consumption are discussed.