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The Lancet. Infectious Diseases Jun 2024
Topics: Cholera; Humans; Global Health; Cholera Vaccines; Health Services Accessibility
PubMed: 38795728
DOI: 10.1016/S1473-3099(24)00306-2 -
Microorganisms Apr 2024In contrast to "frank" pathogens, like , , and , that always have a probability of disease, "opportunistic" pathogens are organisms that cause an infectious disease in a... (Review)
Review
In contrast to "frank" pathogens, like , , and , that always have a probability of disease, "opportunistic" pathogens are organisms that cause an infectious disease in a host with a weakened immune system and rarely in a healthy host. Historically, drinking water treatment has focused on control of frank pathogens, particularly those from human or animal sources (like , , or ), but in recent years outbreaks from drinking water have increasingly been due to opportunistic pathogens. Characteristics of opportunistic pathogens that make them problematic for water treatment include: (1) they are normally present in aquatic environments, (2) they grow in biofilms that protect the bacteria from disinfectants, and (3) under appropriate conditions in drinking water systems (e.g., warm water, stagnation, low disinfectant levels, etc.), these bacteria can amplify to levels that can pose a public health risk. The three most common opportunistic pathogens in drinking water systems are , , and . This report focuses on these organisms to provide information on their public health risk, occurrence in drinking water systems, susceptibility to various disinfectants, and other operational practices (like flushing and cleaning of pipes and storage tanks). In addition, information is provided on a group of nine other opportunistic pathogens that are less commonly found in drinking water systems, including , , , , , , , and several free-living amoebae including and species of The public health risk for these microbes in drinking water is still unclear, but in most cases, efforts to manage , mycobacteria, and risks will also be effective for these other opportunistic pathogens. The approach to managing opportunistic pathogens in drinking water supplies focuses on controlling the growth of these organisms. Many of these microbes are normal inhabitants in biofilms in water, so the attention is less on eliminating these organisms from entering the system and more on managing their occurrence and concentrations in the pipe network. With anticipated warming trends associated with climate change, the factors that drive the growth of opportunistic pathogens in drinking water systems will likely increase. It is important, therefore, to evaluate treatment barriers and management activities for control of opportunistic pathogen risks. Controls for primary treatment, particularly for turbidity management and disinfection, should be reviewed to ensure adequacy for opportunistic pathogen control. However, the major focus for the utility's opportunistic pathogen risk reduction plan is the management of biological activity and biofilms in the distribution system. Factors that influence the growth of microbes (primarily in biofilms) in the distribution system include, temperature, disinfectant type and concentration, nutrient levels (measured as AOC or BDOC), stagnation, flushing of pipes and cleaning of storage tank sediments, and corrosion control. Pressure management and distribution system integrity are also important to the microbial quality of water but are related more to the intrusion of contaminants into the distribution system rather than directly related to microbial growth. Summarizing the identified risk from drinking water, the availability and quality of disinfection data for treatment, and guidelines or standards for control showed that adequate information is best available for management of . For , the risk for this organism has been clearly established from drinking water, cases have increased worldwide, and it is one of the most identified causes of drinking water outbreaks. Water management best practices (e.g., maintenance of a disinfectant residual throughout the distribution system, flushing and cleaning of sediments in pipelines and storage tanks, among others) have been shown to be effective for control of in water supplies. In addition, there are well documented management guidelines available for the control of the organism in drinking water distribution systems. By comparison, management of risks for from water are less clear than for . Treatment of is difficult due to its resistance to disinfection, the tendency to form clumps, and attachment to surfaces in biofilms. Additionally, there are no guidelines for management of in drinking water, and one risk assessment study suggested a low risk of infection. The role of tap water in the transmission of the other opportunistic pathogens is less clear and, in many cases, actions to manage (e.g., maintenance of a disinfectant residual, flushing, cleaning of storage tanks, etc.) will also be beneficial in helping to manage these organisms as well.
PubMed: 38792751
DOI: 10.3390/microorganisms12050916 -
Microorganisms Apr 2024Bacteriophages are currently considered one of the most promising alternatives to antibiotics under the 'One Health' approach due to their ability to effectively combat...
Bacteriophages are currently considered one of the most promising alternatives to antibiotics under the 'One Health' approach due to their ability to effectively combat bacterial infections. This study aimed to characterize species in hatchery water samples collected from an aquaculture farm and investigate the biocontrol potential of their bacteriophages. spp. ( = 32) isolates confirmed by LNA probe-based qPCR were used as hosts. Three phages were isolated. IKEM_vK exhibited a broad host range, infecting ( = 8), ( = 2), ( = 1), and ( = 1). IKEM_v5 showed lytic activity against ( = 4) and ( = 1), while IKEM_v14 was specific to ( = 4). The morphological appearance of phages and their lytic effects on the host were visualized using scanning electron microscopy (SEM). All three phages remained relatively stable within the pH range of 6-11 and up to 60 °C. The lytic activities and biofilm inhibition capabilities of these phages against planktonic cells support their potential applications in controlling vibriosis in aquaculture systems.
PubMed: 38792725
DOI: 10.3390/microorganisms12050895 -
Microorganisms Apr 2024Amid growing concerns about antibiotic resistance, innovative strategies are imperative in addressing bacterial infections in aquaculture. Quorum quenching (QQ), the...
Amid growing concerns about antibiotic resistance, innovative strategies are imperative in addressing bacterial infections in aquaculture. Quorum quenching (QQ), the enzymatic inhibition of quorum sensing (QS), has emerged as a promising solution. This study delves into the QQ capabilities of the probiotic strain D-18 and its products, particularly in 507 communication and biofilm formation. MK was used as a biomarker in this study, and the results confirmed that D-18 effectively inhibits QS. Further exploration into the QQ mechanism revealed the presence of lactonase activity by D-18 that degraded both long- and short-chain acyl homoserine lactones (AHLs). PCR analysis demonstrated the presence of a homologous lactonase-producing gene, ytnP, in the genome of D-18. The study evaluated the impact of D-18 on 507 growth and biofilm formation. The probiotic not only controls the biofilm formation of but also significantly restrains pathogen growth. Therefore, D-18 demonstrates substantial potential for preventing diseases in aquaculture through its QQ capacity. The ability to disrupt bacterial communication and control biofilm formation positions D-18 as a promising eco-friendly alternative to conventional antibiotics in managing bacterial diseases in aquaculture.
PubMed: 38792721
DOI: 10.3390/microorganisms12050890 -
Microorganisms Apr 2024Bacteria in the genus are ubiquitous in estuarine and coastal waters. Some species (including and are known human pathogens causing ailments like cholera, diarrhea,...
Bacteria in the genus are ubiquitous in estuarine and coastal waters. Some species (including and are known human pathogens causing ailments like cholera, diarrhea, or septicemia. Notably, can also cause a severe systemic infection (known as vibriosis) in eels raised in aquaculture facilities. Water samples were periodically collected from the estuary of the Asahi River, located in the southern part of Okayama City, Japan. These samples were directly plated onto CHROMagar Vibrio plates, and colonies displaying turquoise-blue coloration were selected. Thereafter, polymerase chain reaction was used to identify and . A total of 30 strains and 194 strains were isolated during the warm season when the water temperature (WT) was higher than 20 °C. Concurrently, an increase in coliforms was observed during this period. Notably, has two genotypes, designated as genotype 1 and genotype 2. Genotype 1 is pathogenic to humans, while genotype 2 is pathogenic to both humans and eels. The loop-mediated isothermal amplification method was developed to rapidly determine genotypes at a low cost. Of the 194 strains isolated, 80 (41.2%) were identified as genotype 1 strains. Among the 41 strains isolated when the WTs were higher than 28 °C, 25 strains (61.0%) belonged to genotype 1. In contrast, of the 32 strains isolated when the WTs were lower than 24 °C, 27 strains (84.4%) belonged to genotype 2. These results suggest that the distribution of the two genotypes was influenced by WT.
PubMed: 38792707
DOI: 10.3390/microorganisms12050877 -
International Journal of Molecular... May 2024With the increasing rate of the antimicrobial resistance phenomenon, natural products gain our attention as potential drug candidates. Apart from being used as... (Review)
Review
With the increasing rate of the antimicrobial resistance phenomenon, natural products gain our attention as potential drug candidates. Apart from being used as nutraceuticals and for biotechnological purposes, microalgae and phytoplankton have well-recognized antimicrobial compounds and proved anti-infectious potential. In this review, we comprehensively outline the antimicrobial activity of one genus of cyanobacteria (, formerly ) and of eukaryotic microalgae (). Both, especially , are mostly used as nutraceuticals and as a source of antioxidants for health supplements, cancer therapy and cosmetics. Their diverse bioactive compounds provide other bioactivities and potential for various medical applications. Their antibacterial and antifungal activity vary in a broad range and are strain specific. There are strains of with very potent activity and minimum inhibitory concentrations (MICs) as low as 2-15 µg/mL against bacterial fish pathogens including and spp. sp. has demonstrated an inhibition zone (IZ) of 50 mm against . Remarkable is the substantial amount of in vivo studies of showing it to be very promising for preventing vibriosis in shrimp and infection and for wound healing. The innovative laser irradiation of the chlorophyll it releases can cause photodynamic destruction of bacteria. has exhibited MIC values lower than 300 µg/mL and an IZ value of 25.4 mm on different bacteria, while has demonstrated MIC values of 25 and 50 μg/mL against some spp. These values fulfill the criteria for significant antimicrobial activity and sometimes are comparable or exceed the activity of the control antibiotics. The bioactive compounds which are responsible for that action are fatty acids including PUFAs, polysaccharides, glycosides, peptides, neophytadiene, etc. Cyanobacteria, such as , also particularly have antimicrobial flavonoids, terpenes, alkaloids, saponins, quinones and some unique-to-them compounds, such as phycobiliproteins, polyhydroxybutyrate, the peptide microcystin, etc. These metabolites can be optimized by using stress factors in a two-step process of fermentation in closed photobioreactors (PBRs).
Topics: Spirulina; Anti-Infective Agents; Microbial Sensitivity Tests; Humans; Animals; Anti-Bacterial Agents; Microalgae; Chlorophyta
PubMed: 38791586
DOI: 10.3390/ijms25105548 -
Applied Microbiology and Biotechnology May 2024Isolates of Vibrio splendidus are ubiquitously presented in various marine environments, and they can infect diverse marine culture animals, leading to high mortality...
Isolates of Vibrio splendidus are ubiquitously presented in various marine environments, and they can infect diverse marine culture animals, leading to high mortality and economic loss. Therefore, a control strategy of the infection caused by V. splendidus is urgently recommended. Tryptanthrin is a naturally extracted bioactive chemical with antimicrobial activity to other bacteria. In this study, the effects of tryptanthrin on the bacterial growth and virulence-related factors of one pathogenic strain V. splendidus AJ01 were determined. Tryptanthrin (10 μg/mL) could completely inhibit the growth of V. splendidus AJ01. The virulence-related factors of V. splendidus AJ01 were affected in the presence of tryptanthrin. Tryptanthrin resulted an increase in biofilm formation, but lead to reduction in the motility and hemolytic activity of V. splendidus cells. In the cells treated with tryptanthrin, two distinctly differentially expressed extracellular proteins, proteases and flagellum, were identified using SDS-PAGE combined with LC-MS. Real-time reverse transcriptase PCR confirmed that the genes involved in the flagellar formation and hemolysin decreased, whereas specific extracellular proteases and the genes involved in the biofilm formation were upregulated. Two previously annotated luxO genes were cloned, and their expression levels were analyzed at different cell densities. Molecular docking was performed to predict the interaction between LuxO and ATP/tryptanthrin. The two sigma-54-dependent transcriptional regulators showed similar ATP or tryptanthrin binding capacity but with different sites, and the direct competitive binding between ATP and tryptanthrin was present only in their binding to LuxO. These results indicated that tryptanthrin can be used as a bactericide of V. splendidus by inhibiting the growth, bacterial flagella, and extracellular proteases, but increasing the biofilm. Sigma-54-dependent transcriptional regulator, especially the quorum sensing regulatory protein LuxO, was determined to be the potential target of tryptanthrin. KEY POINTS: • Tryptanthrin inhibited the growth of V. splendidus in a dose-dependent manner. • The effect of tryptanthrin on the virulence factors of V. splendidus was characterized. • LuxO was the potential target for tryptanthrin based on molecular docking.
Topics: Biofilms; Vibrio; Anti-Bacterial Agents; Quinazolines; Virulence Factors; Molecular Docking Simulation; Bacterial Proteins; Flagella; Hemolysis; Animals; Microbial Sensitivity Tests; Gene Expression Regulation, Bacterial
PubMed: 38789572
DOI: 10.1007/s00253-024-13158-7 -
The Lancet. Infectious Diseases Jun 2024
Topics: Humans; Cholera; Cholera Vaccines; Disease Outbreaks
PubMed: 38789155
DOI: 10.1016/S1473-3099(24)00301-3 -
Microbiological Research Aug 2024Vibrio alginolyticus is one of the most common opportunistic pathogens in marine animals and humans. In this study, A transposon mutation library of the V. alginolyticus...
Vibrio alginolyticus is one of the most common opportunistic pathogens in marine animals and humans. In this study, A transposon mutation library of the V. alginolyticus E110 was used to identify motility-related genes, and we found three flagellar and one capsular polysaccharide (CPS) synthesis-related genes were linked to swarming motility. Then, gene deletion and complementation further confirmed that CPS synthesis-related gene ugd is involved in the swarming motility of V. alginolyticus. Phenotype assays showed that the Δugd mutant reduced CPS production, decreased biofilm formation, impaired swimming ability, and increased cytotoxicity compared to the wild-type strain. Transcriptome analysis showed that 655 genes (15%) were upregulated and 914 genes (21%) were downregulated in the Δugd strain. KEGG pathway and heatmap analysis revealed that genes involved in two-component systems (TCSs), chemotaxis, and flagella assembly pathways were downregulated in the Δugd mutant. On the other hand, genes involved in pathways of human diseases, biosynthesis ABC transporters, and metabolism were upregulated in the Δugd mutant. The RT-qPCR further validated that ugd-regulated genes are associated with motility, biofilm formation, virulence, and TCSs. These findings imply that ugd may be an important player in the control of some physiological processes in V. alginolyticus, highlighting its potential as a target for future research and potential therapeutic interventions.
Topics: Vibrio alginolyticus; Gene Expression Regulation, Bacterial; Biofilms; Bacterial Proteins; Flagella; Bacterial Capsules; Polysaccharides, Bacterial; Virulence; Animals; Gene Expression Profiling; Gene Deletion; Humans; Vibrio Infections
PubMed: 38788350
DOI: 10.1016/j.micres.2024.127775 -
Tropical Medicine and Infectious Disease May 2024Cholera is highly endemic in many sub-Saharan African countries. The bacterium is responsible for this severe dehydrating diarrheal disease that accounts for over...
Cholera is highly endemic in many sub-Saharan African countries. The bacterium is responsible for this severe dehydrating diarrheal disease that accounts for over 100,000 deaths each year globally. In recent years, the pathogen has been found to invade intestinal layers and translocate into the bloodstream of humans. The non-toxigenic strains of . (non-O1/O139), also known as NOVC, which do not cause epidemic or pandemic cases of cholera, are the major culprits of . bacteremia. In non-cholera-endemic regions, clinical reports on NOVC infection have been noted over the past few decades, particularly in Europe and America. Although low-middle-income countries are most susceptible to cholera infections because of challenges with access to clean water and inappropriate sanitation issues, just a few cases of . bloodstream infections have been reported. The lack of evidence-based research and surveillance of bacteremia in Africa may have significant clinical implications. This commentary summarizes the existing knowledge on the host risk factors, pathogenesis, and diagnostics of NOVC bacteremia.
PubMed: 38787036
DOI: 10.3390/tropicalmed9050103