Source Of Transmission Research Articles

Microbiological Hazards in the Food Chain of Fish and Products, a Focus on Klebsiella spp.

Feeding is an elementary human need from which we obtain the energy and nutrients necessary for development and survival. Health heavily depends on food, which can be a means of different microbial hazards when contaminated at any stage of the food chain, compromising food safety and consumer health. Fish are considered widely produced foods (fishing or aquaculture) and are marketed worldwide; they are also a basic element of the human diet because they are a source of proteins and lipids. On the other hand, owing to their chemical properties (neutral pH and water activity), fish are highly susceptible to contamination by saprophytic and pathogenic microorganisms related to spoilage and risk to human health. Among the contaminating microorganisms in fish are bacteria of the genus Klebsiella, which are considered important in human and animal health worldwide due to their opportunistic pathogenicity, resistance to various antimicrobials, and association with numerous infections at the community and hospital levels, where foods such as fish and other products can serve as important sources of transmission. Therefore, this document presents a bibliographic review focused on describing, in a general way, the genus Klebsiella and its relationship with human health, aquatic animal health, and the safety of fish and products, as well as laboratory analysis procedures and identification of control and prevention measures of this biological hazard in fish and products to safeguard public health.

Outbreak of multi-drug resistant Staphylococcus haemolyticus ST29 in a French neonatal unit

Staphylococcus haemolyticus is a clinically relevant coagulase-negative staphylococcus frequently responsible for hospital-acquired infections, especially in premature newborns. To describe an outbreak of multidrug-resistant S. haemolyticus in a neonatal department. The outbreak was investigated using classical methods, including screening of the patients, genotyping of the isolates and environmental survey. Numerous infection control measures were implemented. In 2022 and 2023, a clonal outbreak of multidrug-resistant S.haemolyticus ST29 (40 infections and 71 carriages) occurred in the neonatology department of a University Hospital in France. The infection control measures implemented only partially controlled the outbreak. Although our investigation did not clearly identify the source and mode of transmission, a reservoir constituted by patients and transmission by healthcare workers are the most likely. This episode occurred in a context of countrywide outbreaks of S.haemolyticus ST29 in several French neonatology departments. This prolonged outbreak of S.haemolyticus ST29 accounted for the increase in the incidence of S.haemolyticus-related infections in French neonatology departments. Implementation of proactive measures is crucial to limit the spread of such pathogens in neonatal ICUs.

P-374. Bacterial Outbreak Investigations Associated with Drug Diversion by U.S. Healthcare Personnel, 1990-2023

Abstract Background Diversion of injectable medications by healthcare personnel (HCP) is widely recognized as a source of bloodborne pathogen transmission. Drug diversion can also cause bloodstream infections (BSIs) but may not be identified as a transmission source due to the myriad of potential etiologies of bacterial outbreaks in healthcare settings. Here, we describe characteristics of drug diversion-related bacterial outbreaks to inform identification and control. Methods We searched PubMed using the key terms “outbreak” or “cluster” and “diversion” to identify outbreaks reported from 1990-2023. Publication references were reviewed to identify additional reports. We excluded outbreaks outside the US and those caused by non-bacterial pathogens. We compiled patient- and outbreak-level data, including infection type, pathogen, length of stay, healthcare setting, diversion mechanism, and epidemiologic investigation strategies. Results We identified six drug diversion-related bacterial outbreaks published between 1991-2019, involving 80 patients. 93% (n=74) of patients presented with BSIs; 93% (n=74) were identified after surgery or procedure; 24% (n=18) of patients with a BSI had a polymicrobial infection. Median outbreak duration was 119 days (range: 38-288). All outbreaks involved water-associated bacteria (Table) and four outbreaks reported BSI onset within 48 hours of admission for at least one patient. Outbreaks necessitated multiple epidemiologic strategies, including routine approaches (e.g., case-control study [n=4]) and techniques specific to medication tampering (e.g., medication concentration testing [n=4]). At least three patients (range: 3-24) in each outbreak had related isolates by molecular typing or whole genome sequencing. Four outbreaks reported tampering with opioids administered by patient-controlled analgesia (PCA) pumps. Conclusion Certain features of healthcare BSI outbreaks, including involvement of water-associated bacteria, post-surgical populations, or rapid infection onset, should prompt consideration of drug diversion as a potential route of transmission. Multifaceted strategies, including evaluation for medication tampering, are needed to identify outbreaks from drug diversion. Disclosures All Authors: No reported disclosures

Transmission patterns of hepatitis E virus.

Hepatitis E virus (HEV) causes sporadic cases in industrialized countries and endemic outbreaks in areas with lower sanitation standards. The wide host reservoir of HEV makes it a potential source of new zoonotic transmission and dissemination in humans. Thus, the perception of HEV as a confined ailment has shifted to one of global concern. Considering HEV's environmental stability and heterogeneity in the host range of HEV's genotypes, various transmission pathways and sources for HEV infections are plausible. Here, we provide an overview on HEV's transmission routes and discuss the role of HEV as a foodborne zoonosis, as well as preventive measures and open research questions.

P-265. No Flu in the Loo: Efficacy of a novel, automated far ultraviolet-C light technology for decontamination of surfaces and aerosolized viral particles in bathrooms

Abstract Background Aerosols generated during toilet flushing are a potential source for transmission of viral and bacterial pathogens in bathrooms. However, manual decontamination of bathrooms after each use is not feasible. Log 10 reduction of organisms on steel disk carriers after 2 hours of far UV-C light exposure* MRSA, methicillin-resistant Staphylococcus aureus; VRE, vancomycin-resistant enterococci; E. coli, Escherichia coli, MS2, bacteriophage MS2 *, 5 of 9 test sites shown Methods We tested the efficacy of a wall-mounted far ultraviolet-C (UV-C) light technology that only delivers far UV-C when people are not present for decontamination of surfaces and aerosolized viral particles in unoccupied hospital bathrooms. A quantitative disk carrier test method was used to test efficacy against organisms on steel disk carriers placed in 9 sites in the bathrooms with an exposure time of 2 hours; Clostridioides difficile spores were exposed for 24 hours. Efficacy against aerosolized bacteriophage MS2 was tested with a 45-minute exposure. Results The far UV-C technology reduced methicillin-resistant Staphylococcus aureus (MRSA), vancomycin-resistant enterococci (VRE), Candida auris, Escherichia coli, and bacteriophage MS2 on disk carriers by >1.9 log 10 at all test sites in 2 hours (Figure), and reduced C. difficile spores by >1.7 log 10 in 24 hours. Aerosolized bacteriophage MS2 was reduced by 4 log 10 plaque-forming units in 45 minutes. The technology consistently turned off when people entered the bathroom and resumed far UV-C delivery after they exited. Conclusion The novel far UV-C light technology could potentially be useful for automated decontamination of bathrooms in healthcare and community settings. Disclosures Curtis Donskey, MD, Clorox: Grant/Research Support|Pfizer: Grant/Research Support

P-254. The Effect of Disinfection with 222-nm Ultraviolet C on Surfaces Contaminated with Clostridioides difficile and Vancomycin-resistant Enterococci in the Bathrooms of Isolation Patients

Abstract Background Contaminated environmental surfaces are important sources of transmission for healthcare-associated pathogens, including Clostridioides difficile (CD) and vancomycin-resistant enterococci (VRE). Toilet surfaces are easily contaminated by pathogens excreted in stools. In this study, we investigated the efficacy of a 222-nm ultraviolet C (UVC) disinfection device, Care222®, for removing bacterial contamination in the bathrooms of isolated patients. Methods This study was conducted in the rooms of five patients diagnosed with C. difficile infection and in the rooms of five patients colonized with VRE. The Care222® device is mounted on a mobile cart and fixed at a 45-degree downward angle. The Care222® emission window was placed 1 m from the farthest end of the toilet seat and at a height of 1.1 m from the floor. At this position, UVC irradiation was performed for 45 min at a total 222-nm UVC fluence of 27 mJ/cm2. Before and after UVC irradiation, samples were collected from the toilet seat and control panel of the electric warm-water bidet toilet seat, in each room, and colony-forming units (CFUs) were determined. Results Disinfection with 222-nm UVC resulted in a significant decrease in the number of CD CFUs compared to the number of CFUs before disinfection (Median CFUs (range), 8 (0–51) vs. 1 (0-5), P=0.004). It also resulted in a significant decrease in the number of VRE CFUs compared to the number of CFUs before disinfection (Median CFUs (range), 7 (1–32) vs. 1 (0-3), P=0.001). Conclusion The disinfection with the 222-nm UVC device significantly reduced CD and VRE surface contamination in the bathrooms of isolated patients. Further studies are required to investigate the effectiveness of 222-nm UVC disinfection for reducing environmental pathogen contamination. Disclosures All Authors: No reported disclosures

The circulating plasma microRNA signature in human visceral leishmaniasis.

Visceral leishmaniasis (VL) is a vector-borne disease caused by the obligate intracellular protozoan Leishmania donovani in India. VL can be complicated by post-kala-azar dermal leishmaniasis (PKDL), a macular or nodular rash that develops in 10%-20% of patients after treatment of VL in India. Patients with PKDL are infectious to sand flies, promoting further transmission of the parasite. MicroRNAs (miRNAs) are 18-25 nt, non-coding RNAs that simultaneously regulate the expression of several or many target transcripts. This study was based on the hypothesis that the host response to L. donovani is modified by distinct sets of miRNAs in VL or PKDL and that these might differ from healthy controls. We investigated this hypothesis using a NanoString panel to profile the miRNAs expressed in the plasma of patients with VL or PKDL diagnosed at a hospital in Bihar, India. We compared these to plasma microRNAs of healthy control individuals from the same endemic villages. miRNAs hsa-miR-223-3p, hsa-miR-191-5p, hsa-miR-23a-3p, and hsa-1285-5p were significantly higher in the plasma samples from patients with VL compared to either PKDL or endemic controls. Prediction programs highlighted potential mRNA targeted by these miRNAs, among which we verified the down-modulation of several transcripts belonging to the NFκB and NLRP3 inflammasome pathways in circulating leukocytes of VL patients. By contrast, miRNA patterns in subjects with PKDL were similar to control subjects, possibly suggesting that the pathogenic immune response during PKDL is primarily localized in the skin.IMPORTANCEInfection of humans with the protozoan Leishmania donovani can be asymptomatic or it can cause fatal visceral leishmaniasis (VL), sometimes followed by the cutaneous complication PKDL. Parasites are spread through sand fly bites in endemic regions, and parasites in post-kala-azar dermal leishmaniasis (PKDL) skin lesions are a source of prolonged parasite transmission to sand flies, compromising disease eradication efforts. Since microRNAs can simultaneously modify the expression of multiple genes, we examined microRNAs in the blood that might be partial determinants of pathogenic responses leading to VL or PKDL. Our studies revealed several miRNAs expressed that are elevated in the plasma of patients with VL, which suppress some of the inflammatory responses that promote parasite killing. However, miRNA profiles were very similar between PKDL patients and controls, raising the possibility that major factors that lead to prolonged retention of parasites in the skin during PKDL are not systemic but are localized in the skin.

High-throughput analysis of microbiomes in a meat processing facility: are food processing facilities an establishment niche for persisting bacterial communities?

BackgroundMicrobial spoilage in meat impedes the development of sustainable food systems. However, our understanding of the origin of spoilage microbes is limited. Here, we describe a detailed longitudinal study that assesses the microbial dynamics in a meat processing facility using high-throughput culture-dependent and culture-independent approaches to reveal the diversity, dispersal, persistence, and biofilm formation of spoilage-associated microbes.ResultsCulture-dependent and culture-independent approaches revealed a large diversity of microbes within the meat facility, including 74 undescribed bacterial taxa and multiple spoilage-associated microbes. Ten out of 10 reconstituted microbial communities formed biofilms, and the biofilm biomass was generally higher at 4 °C than at 25 °C. Isolates obtained at different sampling times or from different sampling sites that differed in fewer than 10 genome-wide single-nucleotide polymorphisms were considered the same (persistent) strains. Strains of Carnobacterium maltaromaticum and Rahnella rivi persisted over a period of 6 months across sampling sites and time, stemming from floor drains in the cooler room. Meat isolates of Carnobacterium divergens, Rahnella inusitata, and Serratia proteamaculans originated from food contact and non-food contact environments of the packaging area.ConclusionsCulture-dependent isolation, complemented by culture-independent analyses, is essential to fully uncover the microbial diversity in food processing facilities. Microbial populations permanently resided within the meat processing facility, serving as a source of transmission of spoilage microbes. The ability of these microbes to coexist and form biofilms facilitates their persistence. Our data together with prior data on persistence of Listeria monocytogenes indicates that microbial persistence in food processing facilities is the rule rather than an exception.-75cynRBG-ecg4-DNt8vX5Video

Waiting areas in tertiary-care hospitals in Pakistan, a major risk for airborne infections

Dear Madam, An airborne infection is any disorder transmitted through the air and caused by microorganisms including bacteria, viruses, and fungi. The most common disorders transmitted by this route include Tuberculosis, Influenza, Measles, Mumps, Coronavirus, MERS-Co V, Smallpox, Chickenpox, Aspergillosis, Blastomycosis, etc. According to the World Health Organization, “Airborne transmission of infectious agents refers to the transmission of disease caused by the dissemination of droplet nuclei that remain infectious when suspended in air over long distance and time” (1). In Pakistan, infections spread in this way also contribute to one of the major factors in the overall prevalence ratio of airborne diseases. Activities such as coughing, sneezing, and talking, which generate aerosolised particles can cause transmission. as. The possibility of spreading contagious disorders tremendously increases when susceptible individuals are placed together with index cases within confined spaces. Hospital waiting areas are among the most common confined spaces that could lead to airborne infections among individuals. (2) Personnel including patients, visitors and working staff are the most likely contributors of transmission sources in hospital boundaries. Other possible sources within the hospitals include dust or aerosols from the floor or furniture, potted plants or flowers, sinks, showers, or aspirating devices. Dust or infective aerosols from contaminated air-conditioning systems may also be a source of airborne infections (3). Airborne transmission in waiting areas of hospitals in Pakistan can be substantially reduced by taking a multi-faceted approach including environmental controls, administrative measures, usage of modern technologies, and personal protective strategies. The best way to prevent airborne infection in waiting areas is by using masks and hand sanitisers. Hand sanitisers should be placed at all the entrance and exit points of waiting areas. Improvement in the ventilatory system through natural and mechanical means plays a significant role in reducing airborne infections. Using extra doors and windows for better airflow is one of the natural ways to reduce infection. Mechanical ways to reduce airborne infection include installing high-efficiency particulate filters and air purifiers in waiting areas. The physical distance of the patients should be increased by increasing the space between seating arrangements. Separate waiting areas should be created for patients with respiratory infections and those without. Implementing screening checkpoints at the hospital entrance to separate patients with infectious diseases is also beneficial. In short, there is a need to resolve this issue for the betterment of health of patients as well as their families.

From Traditional Typing to Genomic Precision: Whole-Genome Sequencing of Listeria monocytogenes Isolated from Refrigerated Foods in Chile.

Ready-to-eat (RTE) foods are the most common sources of Listeria monocytogenes transmission. Whole-genome sequencing (WGS) enhances the investigation of foodborne outbreaks by enabling the tracking of pathogen sources and the prediction of genetic traits related to virulence, stress, and antimicrobial resistance, which benefit food safety management. The aim of this study was to evaluate the efficacy of WGS in the typing of 16 L. monocytogenes strains isolated from refrigerated foods in Chile, highlighting its advantages in pathogen identification and the improvement of epidemiological surveillance and food safety. Using cgMLST, a cluster was identified comprising 2 strains with zero allele differences among the 16 strains evaluated. Ninety-four percent of the isolates (15/16) were serotype 1/2b, and 88% of them (14/16) were ST5. All strains shared identical virulence genes related to adhesion (ami, iap, lapB), stress resistance (clpCEP), invasion (aut, iapcwhA, inlAB, lpeA), toxin production (hly), and intracellular regulation (prfA), with only 13 strains exhibiting the bcrBC and qacJ gene, which confer resistance to quaternary ammonium. The pCFSAN010068_01 plasmids were prevalent, and insertion sequences (ISLs) and composite transposons (cns) were detected in 87.5% of the strains. The presence of various antibiotic resistance genes, along with resistance to thermal shocks and disinfectants, may provide L. monocytogenes ST5 strains with enhanced environmental resistance to the hygiene treatments used in the studied food production plant.

Outbreak of Norovirus Infection in the Hematology Department of a Children's Multidisciplinary Hospital

Relevance. Noroviruses are currently considered the most common cause of sporadic cases and community-acquired outbreaks of acute gastroenteritis (AGE) worldwide [1]. However, outbreaks of healthcare-associated infections (HAI) are also often caused by norovirus etiology [2], including in the Russian Federation [3].Aim. Analysis of key aspects of prevention and anti-epidemic measures against norovirus infection (NVI) in the hematology department.Materials and methods. The following epidemiological research methods were used: descriptive (intensity, dynamics, spatial characteristics of the NVI outbreak); analytical – longitudinal cohort study of the epidemic process of HAI – assessment of hypotheses about the causes and conditions, risk factors and routes of transmission of norovirus among patients and caregivers in the oncohematology department of the children's multidisciplinary hospital.Results and discussion. An outbreak of acute norovirus gastroenteritis of an imported nature was identified in the oncohematology department of a children's multidisciplinary hospital in February 2023, an analysis of the spread of NVI was carried out: the presumed source and mechanism of transmission of norovirus infection was established; the chronology of the spread of norovirus among patients and their caregivers is shown, a list of anti-epidemic measures taken to stop the outbreak is presented, and the difficulties of verifying the epidemiological diagnosis of HAI are reflected (based on the efficiency of laboratory testing of material from patients).Conclusion. Based on the results of the activities carried out, recommendations were proposed for improving preventive and anti-epidemic measures for acute gastroenteritis (AGE) in children's oncohematology departments.

Isolation and identification of causal agents associated with duck mortality in Haor areas of Bangladesh

The duck population is concentrated mostly in the north and northeast wetland areas in Bangladesh. They are reared in close contact with domestic fowls and can be a potential source of many bacterial and viral diseases, as sudden death of ducks is frequently evident. This study aimed to identify the causal agents behind the mortality of ducks in the haor areas of Bangladesh. In total, 66 dead ducks were collected from several locations of different haors in Mymensingh, Kishoreganj, and Netrokona districts. Internal organs of ducklings (n=21) and adult ducks (n=45) were collected as samples. Part of each sample was enriched in nutrient broth for the growth of bacteria, followed by culture in specific media, staining, and biochemical tests were conducted for the primary confirmation of the bacterial isolates. Additionally, inoculum was prepared to propagate viruses in duck embryos. Specific primers were used for the detection of bacterial and viral isolates by PCR. Overall, Escherichia coli (75.75%), Salmonella spp. (12.12%), Staphylococcus spp. (7.57%), Pasteurella spp. (12.12%) and duck plague virus (13.64%) were detected by PCR. All the bacterial and viral isolates were found to be the cause of different duck diseases and major agents for duck mortality in the haor areas. However, they can also be a potential source of pathogen transmission to other domestic fowls. Res. Agric. Livest. Fish. Vol. 11, No. 3, December 2024: 343-352

Human mobility and malaria risk in peri-urban and rural communities in the Peruvian Amazon.

While the global burden of malaria cases has decreased over the last two decades, the disease remains a major international threat, even on the rise in many regions. More than 85% of Peruvian malaria cases are in the Amazonian region of Loreto. Internal mobility primarily related to occupation is thought to be primarily responsible for maintaining endemicity and introducing and reintroducing malaria parasites into areas of anophelism, a challenge for malaria eradication. This study focuses on identifying the sources of malaria transmission and patterns of human mobility in order to understand the movement and transmission of the parasite. The assessment of connectivity produced by human mobility was evaluated in three districts of Loreto, through 10 cross-sectional population screening from 2018 to 2020. We used social network analysis (SNA) to obtain weighted and unweighted degrees of connectivity and explore its variability by socio-demographic characteristics. In addition, we integrated travel history and malaria incidence data to estimate parasite connectivity due to internal human mobility between locations. Finally, we used logistic multivariate regressions to explore the factors associated with Plasmodium spp. infection in mobile individuals. We found that internal human mobility results in high connectivity between communities from the Mazan, Iquitos, and San Juan Bautista districts. We identified nearby destinations that may act as sinks or sources for malaria transmission, including densely populated towns and rural campsites. In addition, we found that being a male, traveling to rural campsites, and working outdoors are associated with Plasmodium spp. infection in travelers from the Mazan district. We provide compelling evidence about how human mobility connects rural communities in the Peruvian Amazon. Using SNA, we uncovered district-specific patterns and destinations, providing further evidence of human mobility heterogeneity in the region. To address the challenge of human mobility and malaria in this setting, geographic heterogeneity of malaria transmission must be considered.

Bag Technique

Home care clinicians have transported equipment and supplies to their patients' homes for decades using a bag that's been referred to as a “nursing bag” or “medical bag,” among others. Regardless of what the bag is called, how it and its contents are managed is essential to prevent the transmission of potentially pathogenic microorganisms from one patient's home to another when making home visits. Bag technique is a component of the standard precautions implemented in home care and an essential practice that applies to all patients receiving in-home care, regardless of their suspected or confirmed infectious state. It is a strategy deployed of infection prevention and control measures to minimize the risk of the home care bag and its contents serving as a source for pathogen transmission. Properly managing the bag and its contents reduces the risk of pathogen transmission.

Assessing the Biosecurity Risk of Footwear as a Fomite for Transmission of Adventitious Infectious Agents to Mice

The soles of staff shoes accessing vivaria can become contaminated on urban streets, potentially serving as a source of fomite-mediated transmission of adventitious agents to laboratory rodents. While shoe covers may mitigate this risk, donning them can lead to hand contamination. Staff accessing our vivaria use motor-driven shoe cleaners hundreds of times daily to remove and collect particulates via a vacuum collection system from the top, sole, and sides of shoes instead of shoe covers. Shoe cleaner debris (SCD) and contact media (CM) exposed to SCD from shoe cleaners in 5 vivaria were assessed by PCR for 84 adventitious agents. SCD and CM samples tested positive for 33 and 37 agents, respectively, and a combined 39 agents total. To assess SCD infectivity, NSG (NOD.Cg-Prkdcscid Il2rgtm1Wjl/SzJ) and Swiss outbred mice were housed for 7 d in direct contact with SCD and oronasally inoculated with a suspension created from SCD collected from each of the 5 vivaria. Mice were tested by PCR and serology at 3, 7, 14, and 63 d postinoculation. All mice remained healthy until the study’s end and tested negative for all agents found in SCD/CM except murine astrovirus 1, Staphylococcus xylosus, and Candidatus Savagella, agents known to be enzootic in the experimental mouse source colony. In a follow-up study, the soles of 27 staff street shoes were directly sampled using CM. Half of CM was used for PCR, while the other half was added as bedding material to a cage containing NSG and Swiss outbred mice. While CM tested positive for 11 agents, all mice were healthy at 63 d postexposure and again positive for only enzootic agents. These results suggest that shoe debris might not be a significant biosecurity risk to laboratory mice, questioning the need for shoe covers or cleaners when entering experimental barrier vivaria.

Presence of multidrug-resistant bacteria on ready-to-use laryngoscope blades and handles: A cross-sectional study.

The presence of microorganisms in laryngoscopes emphasizes the risk to patient safety during orotracheal intubations. A cross-sectional study was carried out in university hospital in the inpatient, emergency, intensive care, and surgical center sectors. Microorganisms were recovered from the blades using a filter membrane and from the handles using swab. They were then sown on blood agar plates and incubated at 35°C (±2°C) for a maximum of 5days. Microorganisms were identified by mass spectrometry, antimicrobial susceptibility tests were carried out for pathogenic bacteria. Associations were made using χ² and Fisher exact tests, and Poisson regression model. A total of 158 blades and 45 handles were analyzed. Microbial growth was observed on 59.5% of the blades and 64.4% of the handles, with fungi and bacteria isolated, such as Enterococcus faecium, Staphylococcus aureus, Klebsiella pneumoniae, Acinetobacter baumannii, Pseudomonas aeruginosa, and Enterobacter sp. Multidrug-resistant bacteria, producing extended-spectrum β-lactamases and carbapenemases, were found. Multidrug-resistant bacteria were found on ready-to-use laryngoscopes. In the surgical center, there was lower probability of microbial growth, while the intensive care sector showed higher probability. This study reinforces the warning that this equipment is a potential source of transmission of microorganisms, especially multiresistant strains.

Influence of Red Blood Cells on Channel Characterization in Cylindrical Vasculature.

Molecular communication via diffusion (MCvD) expects Brownian motions of the information molecules to transmit information. However, the signal propagation largely depends on the geometric characteristics of the assumed flow model, i.e., the characteristics of the environment, design, and position of the transmitter and receiver, respectively. These characteristics are assumed to be lucid in many ways by either consideration of one-dimensional diffusion, unbounded environment, or constant drift. In reality, diffusion often occurs in blood-vessel-like channels. To this aim, we try to study the effect of the biological environment on channel performance. The Red-Blood Cells (RBCs) found in blood vessels enforces a higher concentration of molecules towards the vessel walls, leading to better reception. Therefore, in this paper we derive an analytical expression of Channel Impulse Response (CIR) for a dispersion-advection-based regime, contemplating the influence of RBCs in the model and considering a point source transmitter and a realistic design of the receiver.

Development and Clinical Detection of Rapid Molecular Diagnostic System for Pathogenic Dermatophytes of Tinea Capitis of Multiple Centres in China.

Tinea capitis remains a common fungal infection in children worldwide. Species identification is critical for determining the source of infection and reducing transmission. In conventional methods, macro- and microscopic analysis is time-consuming and results in slow fungal growth or low specificity. We propose a rapid real-time diagnostic PCR method that allows species-specific identification of dermatophytes, including the Microsporum canis complex, Trichophyton mentagrophytes complex, Trichophyton rubrum complex and Trichophyton tonsurans, in patients with tinea capitis. Hair and scrapings samples were collected from 231 patients with tinea capitis who were positive for fungal elements via direct microscopy with potassium hydroxide. Each sample was subjected to a two-step real-time PCR (RT-PCR) assay, which was designed on the basis of differences in the DNA fragments of the internal transcribed spacer (ITS) and β-tubulin covering the Microsporum canis complex, T. mentagrophyte complex, T. rubrum complex, T. tonsurans, T. verrucosum, T. schoenleinii and N. gypseum. In total, 186/231 samples (80.52%) were positive for fungal culture. The two-step RT-PCR was positive in 215/231 samples (93.07%), among which 179 were culture positive. The combined efficacy was 96.81%, which was significantly different when the RT-PCR assays were performed in parallel with fungal culture. A total of 126 samples (54.55%) were identified as Microsporum canis by fungal culture, among which the positive rate of M. canis complex RT-PCR was 97.62% (123/126). A total of 45 samples were negative for fungal culture, of which 80.0% (36/45) were positive by RT-PCR, and the percentage of M. canis complex-positive samples was 53.33% (24/45). The RT-PCR assays were negative for 16/231 samples, among which 7 were culture positive, including M. canis (n = 3), T. violaceum (n = 3) and N. gypseum (n = 1). We developed a new diagnostic assay system using a rapid real-time TaqMan PCR assay with specific primers that can be applied in routine laboratory practice for hair and skin samples of tinea capitis to detect dermatophytes and increase diagnostic efficiency.

Campylobacter jejuni/coli Infection: Is It Still a Concern?

Campylobacteriosis is a leading cause of infectious diarrhea and foodborne illness worldwide. Campylobacter infection is primarily transmitted through the consumption of contaminated food, especially uncooked meat, or untreated water; contact with infected animals or contaminated environments; poultry is the primary reservoir and source of human transmission. The clinical spectrum of Campylobacter jejuni/coli infection can be classified into two distinct categories: gastrointestinal and extraintestinal manifestations. Late complications are reactive arthritis, Guillain–Barré syndrome, and Miller Fisher syndrome. In the pediatric population, the 0–4 age group has the highest incidence of campylobacteriosis. Regarding the use of specific antimicrobial therapy, international guidelines agree in recommending it for severe intestinal infections. Host factors, including malnutrition, immunodeficiency, and malignancy, can also influence the decision to treat. The Centers for Disease Control and Prevention (CDC) has identified antibiotic resistance in Campylobacter as a ‘significant public health threat’ due to increasing resistance to FQs or macrolides. Although numerous vaccines have been proposed in recent years to reduce the intestinal colonization of poultry, none have shown sufficient efficacy to provide a definitive solution.

Free-Space to SMF Integration and Green to C-Band Conversion Based on PPLN.

In this study, we experimentally demonstrate a PPLN-based free-space to SMF (single-mode fiber) conversion system capable of efficient long-wavelength down-conversion from 518 nm, optimized for minimal loss in highly turbid water, to 1540 nm, which is ideal for low-loss transmission in standard SMF. Leveraging the nonlinear optical properties of periodically poled lithium niobate (PPLN), we achieve a wavelength conversion efficiency of 1.6% through difference frequency generation while maintaining a received optical signal-to-noise ratio of 10.4 dB. Our findings underscore the potential of integrating PPLN-based wavelength conversion with fiber optic networks, offering a viable solution for next-generation optical sensor systems that demand real-time, low-latency, and reliable data transmission. This work represents a significant advancement in developing robust and efficient optical sensor technologies, addressing the challenges associated with long-distance transmission and broad-linewidth light sources in optical remote sensing applications.