Human Infectious Diseases Research Articles

Cellular senescence in acute human infectious disease: a systematic review

IntroductionAcute infectious disease represents a significant cause of mortality and morbidity in elderly individuals admitted to the hospital. In its extreme, it presents as sepsis, a systematic inflammatory and immunologic response responsible for self-injurious organ injury. As individuals age, a unique set of factors including immunosenescence predispose them to acquiring an infection and a worse clinical prognosis. This systematic review explores the relationship between cellular senescence, an age-related inflammatory phenomenon, with acute human infectious disease.MethodsEmbase via OVID, Scopus, Web of Science, Global Index Medicus, Cochrane Library via Wiley, and ClinicalTrials.gov were queried. Included studies must have compared at least one of the following measures of cellular senescence between patients with an infection and without an infection: cell cycle inhibition measured via levels of p16INK4a and/or p21CIP1, short telomere length, DNA damage via ɣH2AX, high senescence-associated β galactosidase activity, and inflammation via the detection of senescence associated secretory phenotype (SASP). Manuscripts were screened and data collected via two independent reviewers.ResultsA total of 15,828 studies were screened after duplicates were removed. One hundred and fifty-three full-text articles were assessed for eligibility and a total of 16 original articles were included in analysis. Of the 16 original articles included, 12 (75%) articles were centered on SARS-CoV-2, 2 (12.5%) articles utilized patients infected with Leishmania braziliensis, 1 (6.25%) with Plasmodium falciparum, and 1 (6.25%) with Hepatitis C.ConclusionCurrent literature demonstrates robust upregulation of markers of cellular senescence in the setting of acute SARS-CoV-2, P. falciparum, L. braziliensis, and hepatitis C virus, and that markers of senescence correlate with disease severity and persist for months after resolution. Limitations in the number and types of infectious organisms studied, low sample sizes, modest longitudinal sampling, and a lack of consistency in markers measured, the method of measurement, and the definition of normal values represent ongoing gaps in the literature.Systematic Review Registrationhttps://www.crd.york.ac.uk/prospero/display_record.php?RecordID=421473, Identifier CRD42023421473.

Zebrafish (Danio rerio) as a Model System to Investigate the Role of the Innate Immune Response in Human Infectious Diseases

The zebrafish (Danio rerio) has emerged as a valuable model for studying host-pathogen interactions due to its unique combination of characteristics. These include extensive sequence and functional conservation with the human genome, optical transparency in larvae that allows for high-resolution visualization of host cell-microbe interactions, a fully sequenced and annotated genome, advanced forward and reverse genetic tools, and suitability for chemical screening studies. Despite anatomical differences with humans, the zebrafish model has proven instrumental in investigating immune responses and human infectious diseases. Notably, zebrafish larvae rely exclusively on innate immune responses during the early stages of development, as the adaptive immune system becomes fully functional only after 4–6 weeks post-fertilization. This window provides a unique opportunity to isolate and examine infection and inflammation mechanisms driven by the innate immune response without the confounding effects of adaptive immunity. In this review, we highlight the strengths and limitations of using zebrafish as a powerful vertebrate model to study innate immune responses in infectious diseases. We will particularly focus on host-pathogen interactions in human infections caused by various bacteria (Clostridioides difficile, Staphylococcus aureus, and Pseudomonas aeruginosa), viruses (herpes simplex virus 1, SARS-CoV-2), and fungi (Aspergillus fumigatus and Candida albicans).

Characterization and complete genome sequence of highly lytic phage active against methicillin-resistant Staphylococcus aureus (MRSA) isolated from Egypt

BackgroundMethicillin-Resistant Staphylococcus aureus (MRSA) is one of the most resistant bacteria to antibiotics. S. aureus is an important, widespread pathogen that can cause a variety of infectious diseases in humans and animals. Phages have been recognized as natural, safe, highly specific and effective alternatives agents to antibiotics for preventing and treating bacterial infections caused by MRSA. Therefore, this study aims at the characterization of a novel isolated lytic phage, vB_SauP_ASUmrsa123.MethodsIsolates of Staphylococcus aureus MRSA were obtained on Mannitol Salt Agar and Baird Parker Agar plates and confirmed using VITEK 2. Sewage and clinical samples were used to isolate specific phages for S. aureus MRSA, and plaque assays were used for host range determination on Luria-Bertani (LB) media. The phage morphology of the isolated phage was determined by transmission electron microscopy. The phage’s whole genome sequencing was identified.ResultsA total of 25 isolates of Staphylococci were obtained from different clinical sources and showed typical colonies on Baird-Parker and Mannitol Salt Agar plates. The VITEK 2 automated system revealed that all 25 isolates were confirmed as S. aureus (MRSA). Two of the most antibiotics-resistant isolates were further confirmed using 16S ribosomal RNA sequencing. A lytic phage was detected against the MRSA isolates tested In Vitro, namely vB_SauP_ASUmrsa123. The phage belonged to Rountreeviridae family based on morphological properties observed by TEM and the host range of the isolated phage was tested on the 25 clinical MRSA isolates in Vitro. The one-step growth curve of the isolated phage showed that the latent period was about 55 min, and the burst size was estimated at 167 PFU. The whole genome sequencing and annotation of genes revealed that phage vB_SauP_ASUmrsa123 contained a linear dsDNA with a size of about 17,155 bp with predicted 24 ORFs. Analysis of its genome provides valuable information approximately the variety of phages belonging to the staphylococcal phages class I.ConclusionA lytic Podo Phage vB_SauP_ASUmrsa123 was identified against S. aureus MRSA isolates and its genome was sequenced. The phage was found to be eligible for potential application in biocontrol.

Insights into molecular mechanisms of phytochemicals in quorum sensing modulation for bacterial biofilm control.

Biofilm formation is a common mechanism by which bacteria undergo phenotypic changes to adapt to environmental stressors. The formation of biofilms has a detrimental impact in clinical settings by contributing to chronic infections and promoting antibiotic resistance. Delving into the molecular mechanisms, the quorum sensing (QS) system involves the release of chemical signals for bacterial cell-to-cell communication, which activates and regulates the expression of various genes and virulence factors, including those related to biofilm formation. Accordingly, the QS system becomes a potential target for combating biofilm-associated concerns. Natural products derived from plants have a long history of treating infectious diseases in humans due to their antimicrobial properties, making them valuable resources for screening anti-biofilm agents. This review aims to discover the mechanisms by which phytochemical agents inhibit QS, potentially offering promising new therapies for treating biofilm-associated infections. By targeting the QS system, these phytochemical agents can prevent bacterial aggregation and biofilm formation while also diminishing other bacterial virulence factors. Additionally, it is important to focus on the advancement of techniques and experiments to investigate their molecular mechanisms. A thorough understanding of these mechanisms may encourage further studies to evaluate the safety and efficacy of phytochemical agents used alone or in combination with other strategies.

Antioxidant Activity and Suppression of Intracellular Radical Generation of Streptomyces Strains and Genome Analysis of Strain ET3-23

Actinomycetes, predominantly found in soil, represent a remarkable source of natural products. The natural antioxidants obtained from them have been employed for human infectious diseases. In particular, Streptomyces strains serve as significant sources of natural antioxidants with demonstrated health benefits. The in vitro antioxidant activity and the inhibition of intracellular radical generation by crude extracts from various Streptomyces strains were evaluated and the genome sequence of selected strains was analyzed. Strains CT2-10, NE1-12, and ET3-23 showed 16S rRNA gene sequence similarity to Streptomyces capoamus JCM 4734T (98.94%), Streptomyces nigra 452T (99.78%), and Streptomyces morookaense LMG 20074T (99.49%), respectively. The genome analysis of strain ET3-23 had 106 contigs, with a total length of 8121874 bp and an average G+C content of 71.46%. Ethyl acetate extracts of strains CT2-10, ET3-23, and NE1-12 exhibited, 1,1-diphenyl-2-picrylhydrazyl (DPPH) radical scavenging activity with IC50 555.9 µg/mL, 66.5 µg/mL, and 463.3 µg/mL and showed NO scavenging activity, except for CT2-10. Strain NE1-12 significantly inhibited ROS production induced by hydrogen peroxide on macrophage cells, while strains NE1-12 and CT2-10 inhibited NO production induced by lipopolysaccharides with IC50 82.4 µg/mL and 2.3 µg/mL, respectively. These findings suggest their ability to modulate NO production which is crucial in inflammatory responses and tissue injury. The antioxidant activities of Streptomyces strains indicate their potential as valuable sources of bioactive natural products and effective antioxidant agents, warranting further investigation for therapeutic applications.

Leptospira spp. Antibody Seroprevalence in Stray Dogs and Cats: A Study in Milan, Northern Italy

Leptospirosis is a widespread zoonosis recognised as a re-emerging infectious disease in both humans and dogs, yet the actual seroprevalence of Leptospira in pets in Italy is relatively unknown. The aim of this study was to evaluate Leptospira antibody prevalence in dogs and cats from a shelter by the microscopic agglutination test (MAT), the gold standard test in leptospiral serology, and to assess risk factors for Leptospira infection. This seroepidemiological study investigated the prevalence of leptospiral antibodies in a cohort of 106 dogs and 51 cats housed in a municipal shelter in Milan. Blood samples were collected from the animals during two sampling periods: spring/summer 2014 and autumn/winter 2016/2017. Eight serogroups were evaluated: L. Australis, L. Ballum, L. Canicola, L. Grippotyphosa, L. Icterohaemorrhagiae, L. Pomona, L. Sejroe, and L. Tarassovi. Antibody titres ranged from 1:100 to 1:6400. The results indicated that 21.7% of dogs had antibodies against serogroups L. Icterohaemorrhagiae and L. Australis, making them the most often found. Conversely, none of the cats showed any presence of antibodies. Seropositivity was higher in the spring/summer period (32.7%) than in autumn/winter (11.1%), and no statistically significant results were found regarding sex or age. These findings underscore the importance of ongoing serological surveillance and biosecurity measures in shelter environments to mitigate the zoonotic risk posed by leptospirosis.

A-255 Microbiological Profile and Frequency Distribution of Uropathogens in Brazilian Public Hospitals. Data From a Clinical Laboratory (2018-2023)

Abstract Background Urinary tract infections (UTIs) are among the most common infectious diseases in humans and represent a critical health problem, especially due to a significant rise in global antibiotic use in recent years. The purpose of this study was to describe the main uropathogens and determine the antimicrobial resistance profiles among inpatients at public hospitals in the largest city in Brazil, comparing three different epidemiological periods: pre-Covid-19 (2018-2019), Covid-19 (2020-2021) and post-Covid-19 (2022-2023). Methods A 6-year retrospective review of laboratory data from 12 public hospitals of São Paulo city from January 2018 to December 2023. The urine samples were cultivated onto ChromID® CPS agar plates and then incubated at 35°C for 18-24 h. The bacteria identification was performed by MALDI-TOF mass spectrometry (Vitek-MS), and the minimal inhibitory concentrations of antibiotics were determined using the Vitek®2 system. Only positive results with one bacterial species and a colony count ≥ 105 CFU/mL was considered for descriptive analysis. Results In the 6-year period, a total of 58,738 microorganisms from hospitalized patients were included. The frequency of isolates detected during the period were: 33.9% (19,338/58,738) in pre-Covid-19, 30.1% (17,688/58,738) in Covid-19 and 36.9% (21,712/58,738) in post-Covid-19 period. The top ten microorganisms’ prevalence detected in pre-Covid-19, Covid-19 and post-Covid-19 periods were as follow: 23,951 Escherichia coli (47.5%; 37.1%; 37.7%), 9,247 Klebsiella pneumoniae (12.5%; 14.3%; 19.8%), 7,640 Candida spp. (8.8%; 19.2%; 11.7%), 5,476 Enterococcus spp. (8%; 10%; 9.9%), 3,101 Proteus mirabilis (5.56%; 4.9%; 5.4%), 2,166 Pseudomonas aeruginosa (3.3%; 3.5%; 4.1%), 1,252 Coagulase-Negative Staphylococcus (CoNS) (2.5%; 1.6%; 2.2%), 1,166 Enterobacter spp. (2.3%; 2.1%; 1.6%), 1,088 Streptococcus spp. (3.6%; 1.2%; 0.8%) and 758 Acinetobacter spp. (0.8%; 1.5%; 1.5%). Extended spectrum beta-lactamase rates for E. coli were 16.8% and 20.2% and for K. pneumoniae were 65.7% and 65.2% in Covid-19 and Post-Covid-19 periods, respectively. The resistance to carbapenems was observed mainly in Acinetobacter spp. (85.7%, 93.8% and 80.7%), K. pneumoniae (38.3%, 42.6% and 47.3%), Pseudomonas aeruginosa (22.3%, 23.1% and 25%), and Proteus spp. (0.2%, 1.9% and 5%). Between the Gram-positive cocci, the resistance to vancomycin was observed mainly in E. faecium (43.5%, 37.5%, 30.2%) and the resistance to methicillin was detected in S. aureus (30.1%, 35.8%, 34.1%) and CoNS (31.9%, 47.8%, 53.5%). Conclusions In this study, we observed an increase in the incidence of Candida spp. coinciding with the start of the pandemic period. Overall, the frequency of uropathogens isolated from hospital centers increased and exhibited high resistance to various classes of antimicrobial agents. ESBL-producing K. pneumoniae and Carbapenem-resistant Enterobacteriacea, and nonfermenters such as Acinetobacter spp. and P. aeruginosa constitute serious problems in Brazilian hospitals.

A systematic review and guide for using multi-response statistical models in co-infection research.

The simultaneous infection of organisms with two or more co-occurring pathogens, otherwise known as co-infections, concomitant infections or multiple infections, plays a significant role in the dynamics and consequences of infectious diseases in both humans and animals. To understand co-infections, ecologists and epidemiologists rely on models capable of accommodating multiple response variables. However, given the diversity of available approaches, choosing a model that is suitable for drawing meaningful conclusions from observational data is not a straightforward task. To provide clearer guidance for statistical model use in co-infection research, we conducted a systematic review to (i) understand the breadth of study goals and host-pathogen systems being pursued with multi-response models and (ii) determine the degree of crossover of knowledge among disciplines. In total, we identified 69 peer-reviewed primary studies that jointly measured infection patterns with two or more pathogens of humans or animals in natural environments. We found stark divisions in research objectives and methods among different disciplines, suggesting that cross-disciplinary insights into co-infection patterns and processes for different human and animal contexts are currently limited. Citation network analysis also revealed limited knowledge exchange between ecology and epidemiology. These findings collectively highlight the need for greater interdisciplinary collaboration for improving disease management.

Quantifying age-specific household contacts in Aotearoa New Zealand for infectious disease modelling.

Accounting for population age structure and age-specific contact patterns is crucial for accurate modelling of human infectious disease dynamics and impact. A common approach is to use contact matrices, which estimate the number of contacts between individuals of different ages. These contact matrices are frequently based on data collected from populations with very different demographic and socio-economic characteristics from the population of interest. Here we use a comprehensive household composition dataset based on Aotearoa New Zealand census and administrative data to construct a household contact matrix and a synthetic population that can be used for modelling. We investigate the behaviour of a compartment-based and an agent-based epidemic model parametrized using these data, compared with a commonly used contact matrix that was constructed by projecting international data onto New Zealand's population. We find that using the New Zealand household data, either in a compartment-based model or in an agent-based model, leads to lower attack rates in older age groups compared with using the projected contact matrix. This difference becomes larger when household transmission is more dominant relative to non-household transmission. We provide electronic versions of the synthetic population and household contact matrix for other researchers to use in infectious disease models.

A Novel Bifidobacterium longum Subsp. longum T1 Strain from Cow's Milk: Homeostatic and Antibacterial Activity against ESBL-Producing Escherichia coli.

Background/Objectives: The global emergence of antibiotic-resistant zooanthroponotic Escherichia coli strains, producing extended-spectrum beta-lactamases (ESBL-E) and persisting in the intestines of farm animals, has now led to the development of a pandemic of extra-intestinal infectious diseases in humans. The search for innovative probiotic microorganisms that eliminate ESBL-E from the intestines of humans and animals is relevant. Previously, we received three isolates of bifidobacteria: from milk of a calved cow (BLLT1), feces of a newborn calf (BLLT2) and feces of a three-year-old child who received fresh milk from this calved cow (BLLT3). Our goal was to evaluate the genetic identity of BLLT1, BLLT2, BLLT3 isolates using genomic DNA fingerprinting (GDF), to study the tolerance, adhesion, homeostatic and antibacterial activity of BLLT1 against ESBL-E. Methods: We used a complex of microbiological, molecular biological, and immunological methods, including next generation sequencing (NGS). Results: GDF showed that DNA fragments of BLLT2 and BLLT3 isolates were identical in number and size to DNA fragments of BLLT1. These data show for the first time the possibility of natural horizontal transmission of BLLT1 through with the milk of a calved cow into the intestines of a calf and the intestines of a child. BLLT1 was resistant to gastric and intestinal stresses and exhibited high adhesive activity to calf, pig, chicken, and human enterocytes. This indicates the unique ability of BLLT1 to inhabit the intestines of animals and humans. We are the first to show that BLLT1 has antibacterial activity against ESBL-E strains that persist in humans and animals. BLLT1 produced 145 ± 8 mM of acetic acid, which reduced the pH of the nutrient medium from 6.8 to 5.2. This had an antibacterial effect on ESBL-E. The genome of BLLT1 contains ABC-type carbohydrate transporter gene clusters responsible for the synthesis of acetic acid with its antibacterial activity against ESBL-E. BLLT1 inhibited TLR4 mRNA expression induced by ESBL-E in HT-29 enterocytes, and protected the enterocyte monolayers used in this study as a bio-model of the intestinal barrier. BLLT1 increased intestinal alkaline phosphatase (IAP) as one of the main molecular factors providing intestinal homeostasis. Conclusions: BLLT1 shows promise for the creation of innovative functional nutritional products for humans and feed additives for farm animals that will reduce the spread of ESBL-E strains in the food chain.

Molecular detection of Rickettsia aeschlimannii, Candidatus Rickettsia shennongii, Rickettsia sp. and Coxiella burnetii in ticks collected from camels

Tick-borne bacteria of the genera Rickettsia and Coxiella cause several emerging veterinary and human infectious diseases. Ticks of the genus Hyalomma are medically important vectors due to their potential role in the transmission of pathogens to vertebrate hosts. There is an inadequate knowledge on tick-borne Rickettsia spp. and Coxiella spp. in ticks infesting transhumant camels in Pakistan. In this study, we conducted a molecular survey for screening of Rickettsia spp. and Coxiella spp. in ticks infesting camels. Seven hard tick species including Hyalomma dromedarii, Hyalomma anatolicum, Hyalomma scupense, Hyalomma isaaci, Hyalomma turanicum, Hyalomma asiaticum, and Rhipicephalus sanguineus s.l were confirmed on camels in three distinct physiographic regions of Khyber Pakhtunkhwa, Pakistan. A subset of morphologically identified ticks were subjected to molecular assays for the genetic characterization of ticks and the detection and genetic characterization of Rickettsia and Coxiella species using standard genetic markers. Ticks screened for pathogens resulted in the detection of Rickettsia aeschlimannii and Candidatus Rickettsia shennongii and Coxiella burnetii. The molecular analysis further reveals the presences of an undetermined Rickettsia aeschlimannii-like species, that is making a distinct phylogenetic clade with R. aeschlimannii. The detection of pathogens in camel ticks poses potential health hazards as these ticks frequently bites humans. Molecular screening of Rickettsia spp. and Coxiella spp. associated with camel ticks is a preliminary step toward the surveillance of evaluating their zoonotic threats in the region.

Prussian-Blue-Nanozyme-Enhanced Simultaneous Immunochromatographic Control of Two Relevant Bacterial Pathogens in Milk

Salmonella typhimurium and Listeria monocytogenes are relevant foodborne bacterial pathogens which may cause serious intoxications and infectious diseases in humans. In this study, a sensitive immunochromatographic analysis (ICA) for the simultaneous detection of these two pathogens was developed. For this, test strips containing two test zones with specific monoclonal antibodies (MAb) against lipopolysaccharides of S. typhimurium and L. monocytogenes and one control zone with secondary antibodies were designed, and the double-assay conditions were optimized to ensure high analytical parameters. Prussian blue nanoparticles (PBNPs) were used as nanozyme labels and were conjugated with specific MAbs to perform a sandwich format of the ICA. Peroxidase-mimic properties of PBNPs allowed for the catalytic amplification of the colorimetric signal on test strips, enhancing the assay sensitivity. The limits of detection (LODs) of Salmonella and Listeria cells were 2 × 102 and 7 × 103 cells/mL, respectively. LODs were 100-fold less than those achieved due to the ICA based on the traditional gold label. The developed double ICA was approbated for the detection of bacteria in cow milk samples, which were processed by simple dilution by buffer before the assay. For S. typhimurium and L. monocytogenes, the recoveries from milk were 86.3 ± 9.8 and 118.2 ± 10.5% and correlated well with those estimated by the enzyme-linked immunosorbent assay as a reference method. The proposed approach was characterized by high specificity: no cross-reactivity with other bacteria strains was observed. The assay satisfies the requirements for rapid tests: a full cycle from sample acquisition to result assessment in less than half an hour. The developed ICA has a high application potential for the multiplex detection of other foodborne pathogens.

Bridging one health and sustainable analysis: enrofloxacin quantification amid combined therapy and its active metabolite in various matrices using green RP-HPLC

Antibiotics play a crucial role in the treatment of infectious diseases in both humans and animals. However, their extensive utilization has caused significant potential harm to both wildlife and humans. Enrofloxacin (ENR) is a common veterinary antibiotic, which is not approved for human use due to associated toxicities. It is often combined with other antibiotics to expand the antibacterial range. It is crucial to monitor and measure the levels of ENR medication in various matrices. RP-HPLC is highly effective for analyzing antibiotics due to its sensitivity, specificity, and ability to handle complex samples. By adopting eco-friendly solvents, decreasing solvent consumption, and limiting waste we developed a method for determination and quantification of ENR, amoxicillin (AMX), and ENR active metabolite in different matrices. The method utilized a reversed stationary phase and a mobile phase composed of phosphate buffer pH 3.0: ethanol (90:10 v/v) pumped at 1.0 mL/min and UV detection at 254.0 nm. Moreover, a comprehensive assessment of the environmental friendliness of the established method was conducted using various tools including the Green Certificate Classification (GCC) and Analytical Greenness AGREE and RGB12. The method was validated for its accuracy and precision in quantifying ENR, demonstrating its potential for the effective monitoring of ENR and contributing to public health protection.Graphical

Prediction of antimicrobial resistance of Klebsiella pneumoniae from genomic data through machine learning.

Antimicrobials, such as antibiotics or antivirals are medications employed to prevent and treat infectious diseases in humans, animals, and plants. Antimicrobial Resistance occurs when bacteria, viruses, and parasites no longer respond to these medicines. This resistance renders antibiotics and other antimicrobial drugs ineffective, making infections challenging or impossible to treat. This escalation in drug resistance heightens the risk of disease spread, severe illness, disability, and mortality. With datasets now containing hundreds or even thousands of pathogen genomes, machine learning techniques are on the rise for predicting antibiotic resistance in pathogens, prediction based on gene content and genome composition. Aim of this work is to combine and incorporate machine learning methods on bacterial genomic data to predict antimicrobial resistance, we will focus on the case of Klebsiella pneumoniae in order to support clinicians in selecting appropriate therapy.

Highly-Efficient Selection of Aptamers for Quantitative Fluorescence Detecting Multiple IAV Subtypes.

Influenza A virus (IAV) can cause infectious respiratory diseases in humans and animals. IAVs mutate rapidly through antigenic drift and shift, resulting in the emergence of numerous IAV subtypes and significant challenges for IAV detection. Therefore, achieving the simultaneous detection of multiple IAVs is crucial. In this work, three specific aptamers targeting the hemagglutination (HA) protein of the influenza A H5N1, H7N9, and H9N2 viruses were screened using a multichannel magnetic microfluidic chip. The aptamers exhibit nanomolar affinity and excellent specificity for the HA protein of H5N1, H7N9, and H9N2 viruses. Furthermore, three specific aptamers were truncated and labeled with different fluorescence markers to realize fluorescence quantitative detection of influenza A H5N1, H7N9, and H9N2 viruses through an aptamer sandwich assay in 1 h. The limit of detection (LOD) of the developed method is 0.38 TCID50/mL for the H5N1 virus, 0.75 TCID50/mL for the H7N9 virus, and 1.14 TCID50/mL for the H9N2 virus. The detection method has excellent specificity, strong anti-interference ability, and good reproducibility. This work provides a sensitive quantitative detection method for the H5N1, H7N9, and H9N2 viruses, enabling quantitative fluorescence detection for multiple IAV subtypes.

Understanding the transmission of bacterial agents of sapronotic diseases using an ecosystem-based approach: A first spatially realistic metacommunity model.

Pathogens such as bacteria, fungi and viruses are important components of soil and aquatic communities, where they can benefit from decaying and living organic matter, and may opportunistically infect human and animal hosts. One-third of human infectious diseases is constituted by sapronotic disease agents that are natural inhabitants of soil or aquatic ecosystems. They are capable of existing and reproducing in the environment outside of the host for extended periods of time. However, as ecological research on sapronosis is infrequent and epidemiological models are even rarer, very little information is currently available. Their importance is overlooked in medical and veterinary research, as well as the relationships between free environmental forms and those that are pathogenic. Here, using dynamical models in realistic aquatic metacommunity systems, we analyze sapronosis transmission, using the human pathogen Mycobacterium ulcerans that is responsible for Buruli ulcer. We show that the persistence of bacilli in aquatic ecosystems is driven by a seasonal upstream supply, and that the attachment and development of cells to aquatic living forms is essential for such pathogen persistence and population dynamics. Our work constitutes the first set of metacommunity models of sapronotic disease transmission, and is highly flexible for adaptation to other types of sapronosis. The importance of sapronotic agents on animal and human disease burden needs better understanding and new models of sapronosis disease ecology to guide the management and prevention of this important group of pathogens.

Plasmid vector(s) in Bacillus thuringiensis harbor genes for insect pest control and for neglected infectious diseases in humans

Plasmids (circular DNA molecules) represent an ingenious strategy for horizontal gene transfer in prokaryotes and eukaryotic cells. Plasmids harbored in bacteria are responsible for the spread of traits such as antibiotic resistance, virulence factors, and the machinery for the horizontal gene transfer e.g., type IV secretion systems. Remarkably, Bacillus thuringiensis (Bt) cryptic plasmids encode and carry genes that, under the host environment, replicate and concomitate with sporulation, producing parasporal crystalline proteins of two major types, crystalline (Cry) and cytolytic (Cyt), the former toxic against different orders of insects such as Lepidopterans, Coleopterans, and Dipterans (Cry proteins, MW 50–130 KDa); Cyt proteins, produced by B. thuringiensis subspecies israelensis (Bti)(MW 27-kDa) are toxic against Dipterans, i.e., mosquitoes and black flies. The X-Ray tridimensional structure for both types of toxins, formed by three domains, mostly of beta sheets antiparallel (Domain II and Domain III) linked through loops of different lengths. Domain I is a bundle of alpha helices. This structure is characterized by five conserved blocks, implying a conservation in the mode of action. Cyt proteins possess two alpha helices and some beta sheets with a structure similar to the antimicrobial peptides. Indeed, the mode of action proposed is mediated by the toxin-lipid interaction that hypothetically could result in transmembrane ionic channel formation. Several pieces of evidence support the action of both toxins in insects and mammals. The question is to what extent these Bt/Bti plasmid-encoded Cry or Cyt genes can be applied as bioinsecticides individually or in combination with Lysinibacillus sphaericus. The feasibility of being considered a promising and safe biological strategy for crop pests and vector-borne neglected infectious diseases is an issue pinpointed in the present review.

Zebrafish as an effective model for evaluating phage therapy in bacterial infections: a promising strategy against human pathogens.

The escalating prevalence of antibiotic-resistant bacterial infections necessitates urgent alternative therapeutic strategies. Phage therapy, which employs bacteriophages to specifically target pathogenic bacteria, emerges as a promising solution. This review examines the efficacy of phage therapy in zebrafish models, both embryos and adults, which are proven and reliable for simulating human infectious diseases. We synthesize findings from recent studies that utilized these models to assess phage treatments against various bacterial pathogens, including Enterococcus faecalis, Pseudomonas aeruginosa, Mycobacterium abscessus, Staphylococcus aureus, Klebsiella pneumoniae, Acinetobacter baumannii, and Escherichia coli. Methods of phage administration, such as circulation injection and bath immersion, are detailed alongside evaluations of survival rates and bacterial load reductions. Notably, combination therapies of phages with antibiotics show enhanced efficacy, as evidenced by improved survival rates and synergistic effects in reducing bacterial loads. We also discuss the transition from zebrafish embryos to adult models, emphasizing the increased complexity of immune responses. This review highlights the valuable contribution of the zebrafish model to advancing phage therapy research, particularly in the face of rising antibiotic resistance and the urgent need for alternative treatments.

Multidrug Resistance of Escherichia coli in cats and the Level of Understanding of Cat Owners on Antimicrobial Resistance

Multidrug resistance poses a global health risk to humans, animals, and the environment.The impact of this issue is so great that it has gained international attention, ranging from the rising morbidity to the mortality rate of infectious diseases in humans and animals. Because of their peculiar eliminative behavior habit of burying their waste in the ground, cats may contribute to the spread of microorganisms resistant to antibiotics. The purpose of this study was to map the prevalence of antibiotic-resistant E. coli bacteria in cats and to determine the degree of cat owners' comprehension as a risk factor for the development of antimicrobial resistance. In this investigation, 353 cat anal swab samples were found to contain E. coli. The study was carried out in 2023 between March and May. The Mueller Hilton Agar medium was used to test for multidrug resistance to beta-lactam, aminoglycoside, and tetracycline class antibiotics using the diffusion method. Using a questionnaire, the degree of knowledge on antibiotic resistance among 373 cat owners was assessed. Respondent variables include identification, knowledge, demeanor, attitude, and cat care. After that, data were descriptively examined. E. coli was detected in 87.82% (310/353) of the cat anal swab samples (n = 353) in this investigation. Additionally, multidrug resistance was shown in 7.4% (23/310) of the isolates; this frequency was higher in stray cats (8.75%) than in domestic cats (6%). For ampicillin, tetracycline, and streptomycin, the rates of antimicrobial resistance were 28.39% (88/310), 15.81% (49/310), and 14.84% (46/310), in that order. According to an analysis of the questionnaires used to gauge cat owners' comprehension of antimicrobial-resistant events, 64.3% (240/373) of the owners did not know what antimicrobial resistance was. In addition, 72.7% (271/373) of the cat owners were aware of the medications their cats were given, and 66% (246/373) of them knew how to give antibiotics to their pets. These findings are consistent with the findings of another survey that showed 70% (261/373) of cat owners took their sick cats to the veterinarian. Compared to domestic cats, stray cats in this study had a higher rate of multidrug resistance.This is consistent with the relatively positive findings of a survey on cat owners' comprehension of cat maintenance and care; yet, the poor awareness of antimicrobial resistance among cat owners may contribute to its emergence. To raise awareness regarding antimicrobial resistance in cats, cat owners need to get education.

Signal recognition particle RNA is critical for genetic competence and virulence of Streptococcus pneumoniae.

Streptococcus pneumoniae (pneumococcus) causes multiple important infectious diseases in humans. The signal recognition particle (SRP) complex, which comprised 4.5S small cytoplasmic RNA (ScRNA), and the Ffh and FtsY proteins, mediates membrane targeting and translocation of secreted proteins in all organisms. However, the role of SRP and ScRNA has not been characterized during the induction of the competence system for genetic transformation and virulence in pneumococcus. By using a combination of genetic, biochemical, proteomic, and imaging approaches, we demonstrated that the SRP complex plays a significant role in membrane targeting of competence system-regulated effectors important for genetic transformation, virulence during bacteremia and pneumonia infections, and nutritional acquisition.