Agents Of Infections Research Articles

Genomic analysis of Ralstonia pickettii reveals the genetic features for potential pathogenicity and adaptive evolution in drinking water.

Ralstonia pickettii, the most critical clinical pathogen of the genus Ralstonia, has been identified as a causative agent of numerous harmful infections. Additionally, Ralstonia pickettii demonstrates adaptability to extreme environmental conditions, such as those found in drinking water. In this study, we conducted a comprehensive genomic analysis to investigate the genomic characteristics related to potential pathogenicity and adaptive evolution in drinking water environments of Ralstonia pickettii. Through phylogenetic analysis and population genetic analysis, we divided Ralstonia pickettii into five Groups, two of which were associated with drinking water environments. The open pan-genome with a large and flexible gene repertoire indicated a high genetic plasticity. Significant differences in functional enrichment were observed between the core- and pan-genome of different groups. Diverse mobile genetic elements (MGEs), extensive genomic rearrangements, and horizontal gene transfer (HGT) events played a crucial role in generating genetic diversity. In drinking water environments, Ralstonia pickettii exhibited strong adaptability, and the acquisition of specific adaptive genes was potentially facilitated by genomic islands (GIs) and HGT. Furthermore, environmental pressures drove the adaptive evolution of Ralstonia pickettii, leading to the accumulation of unique mutations in key genes. These mutations may have a significant impact on various physiological functions, particularly carbon metabolism and energy metabolism. The presence of virulence-related elements associated with macromolecular secretion systems, virulence factors, and antimicrobial resistance indicated the potential pathogenicity of Ralstonia pickettii, making it capable of causing multiple nosocomial infections. This study provides comprehensive insights into the potential pathogenicity and adaptive evolution of Ralstonia pickettii in drinking water environments from a genomic perspective.

Immunological aspects of vaccination in HIV-infected patients

Until recently, HIV infection does not lose its relevance. In 2022, 630 000 people died and 1.3 million people became infected with the human immunodeficiency virus (HIV). HIV-positive persons develop more infectious diseases than healthy people do; the causative agents are mainly opportunistic microorganisms. Streptococcus pneumoniae is the main causative agent of infection in the lungs in HIV-infected persons. In order to prevent the development of severe pneumococcal infections and to overcome antibiotic resistance, vaccines have been developed. There are polysaccharide (PPV) and conjugate (PCV) vaccines. According to clinical recommendations, vaccination of previously unvaccinated HIV-infected patients is carried out regardless of T-helper cell level. However, no data were found on the effect of PCV13 on immunological memory cells. The purpose of this study is to assess an effect of PCV13 vaccination on the immune system in HIV-infected subjects.
 Materials and methods. The study included 200 patients with HIV infection, which were divided into two groups: I — received a dose of PCV13 (n = 100) and control group (n = 100). During the first visit, immunological and microbiological studies were carried out. On the second visit, a PCV13 was injected into the deltoid muscle. The third visit was made a year later, where immunological and microbiological studies were repeated. Participants were divided into 4 subgroups depending on CD4+ T cell level. The microbial study was done using a swab collected from the back of the throat.
 Results. During the immunological examination at visit 1, abnormalities were detected in all examined populations and immune cell subsets. At 12 months post-vaccination, the median levels of CD3+CD4+ and CD45RO+ T lymphocytes in the immunized group were higher than pre-vaccination levels compared to control group, in which the values changed insignificantly. Our data confirm the immunological effectiveness of PCV13 administration in HIV-infected patients. In patients with peripheral blood CD19+ lymphocyte deficiency, had increased microbial detection rate (p = 0.003).
 Conclusion. As a result, due to the high risk of pneumococcal pneumonia, HIV-infected patients should be immunized with a 13-valent pneumococcal conjugate vaccine.

Epizootological situation and epidemiological risks for natural focal infections in the territory of new subjects of the Russian Federation (Donetsk People's Republic, Lugansk People's Republic, Zaporozhye and Kherson regions)

An epizootological inspection of the liberated territories of the Donetsk and Lugansk People's Republics, Zaporozhye and Kherson regions was carried out. It was established that the faunal complex of small mammals, hare-like and ectoparasites, as well as their number, make it possible to ensure the circulation of natural focal infections identified by the results of laboratory studies: tularemia, Crimean hemorrhagic fever (CHF), West Nile fever (WNF), ixodic tick-borne borreliosis (ITB), rickettsiosis, human granulocytic anaplasmosis (HGA), leptospirosis, hemorrhagic fever with renal syndrome (HFRS), Q fever, intestinal yersiniosis, Batai, Inco, Sindbis, Tyaginya fevers. For the first time, the PCR method in field material from the Zaporozhye region (Berdyansk and Melitopol regions) detected the Crimean-Congo hemorrhagic fever virus, on the territory of the Donetsk and Lugansk People's Republics in the populations of small mammals (rodents and insectivores), the circulation of viruses Inco, Sindbis, Tyagin, Batai was established. In the territories of Kherson and Zaporozhye regions, the presence of combined and conjugated natural foci of ixodic tick-borne borreliosis, rickettsiosis and human granulocytic anaplasmosis is determined. According to the results of molecular genetic analysis, it was shown that the causative agents of natural focal infections (Crimean hemorrhagic fever, West Nile fever, ixodic tick-borne borreliosis, rickettsiosis) identified in 2023 are genetically close to strains circulating in the regions of the south European part of Russia.

Impact of the COVID-19 Pandemic on Diabetic Foot Patients: A Shift in the Infectious Agent Profile Toward Nonfermentative Gram-Negative Bacilli.

Diabetes foot infection is a very important public health problem that causes serious health problems, mortality, and high health expenditures, and is one of the most important complications of diabetes mellitus. There are concerns that approaches such as limited personal visits to doctors, avoidance of hospitals, and restrictions on nonemergency surgical procedures during the coronavirus disease of 2019 pandemic pose a threat to those with diabetic foot problems, including diabetic foot ulcers (DFUs), ischemia, and infection, resulting in increased limb loss and mortality. This multicenter, retrospective, cross-sectional study was conducted in 14 tertiary care hospitals from various regions of Turkey. A total of 1,394 patient records were evaluated, 794 of which were between January 1, 2019, and January 30, 2020 (prepandemic [Pre-P]), and 605 of which were between February 1, 2020, and February 28, 2021 (pandemic period [PP]). During the PP, diabetic foot patient follow-up decreased by 23.8%. In addition, the number of hospitalizations attributable to DFU has decreased significantly during the PP (P = .035). There was no difference between the groups regarding patient demographics, medical history, DFU severity, biochemical and radiologic findings, or comorbidities, but the mean duration of diabetes mellitus years was longer in patients in the Pre-P than in those in the PP (15.1 years versus 13.7 years). There was no difference between the two groups in terms of major complications such as limb loss and mortality, but infection recurrence was higher in the PP than in the Pre-P (12.9% versus 11.4%; P < .05). The prevalence of nonfermentative gram-negative bacteria as causative agents in DFU infections increased during the PP. In particular, the prevalence of carbapenem-resistant Pseudomonas spp. increased statistically during the PP. The rapid adaptation to the pandemic with the measures and changes developed by the multidisciplinary diabetic foot care committees may be the reasons why there was no increase in complications because of DFU during the pandemic in Turkey.

Change of epidemiological characteristics of four respiratory viral infections in children before and during COVID-19 pandemic

ObjectivesViruses are the main infectious agents of acute respiratory infections (ARIs) in children. We aim to describe the changes in epidemic characteristics of viral ARIs in outpatient children before and during the COVID-19 pandemic. Patients and methodsFrom 2017 to 2022, the results of viral detection in oral pharyngeal swabs in 479,236 children with ARIs in the outpatient department of Children’s Hospital, Zhejiang University School of Medicine, were retrospectively analyzed. Viral antigens, including adenovirus (ADV), influenza A (FLUA), influenza B (FLUB) and respiratory syncytial virus (RSV) were detected by the colloidal gold method. ResultsThe median age was 3.4 (1.6–5.6) years. Among all the children, 159,895 cases (33.4 %) were positive for at least one virus. The total positive rate for ADV, FLUA and FLUB during the pandemic period was lower than during the pre-pandemic period in every season (pre-pandemic period vs. pandemic period11.7 % vs. 4.7 %, 13.9 % vs. 9.2 %, 7.0 % vs. 5.2 %, respectively, with overall p value < 0.001). However, the positive rate fir RSV was not significantly different between the pre-pandemic period and the pandemic period (5.6 % vs. 5.8 %, p = 0.117). Atypical timing of RSV (summer-autumn 2021) and FLUA (summer 2022) was noted. ConclusionsPublic health interventions for different pathogens are maximally effective. While positive rates for ADV, FLUA and FLUB decreased during the COVID-19 pandemic period, positive rates for RSV remained similar. In RSV and FLUA, off-season outbreaks were observed. Measures need to be taken to protect children from possible infection surges due to immunity debt having accrued over the last three years.

Lessons from the coronavirus pandemic: a review of how the disease spreads in indoor spaces

Abstract In the post-coronavirus era, it is important to understand how infections spread in the indoor environment. The modes of transmission that are of interest to this research are droplet-borne and airborne transmission. In these transmission cases, there is a dependency on air to transport pathogens. The buoyancy of pathogens depends on the mass of the particles or droplets, volume of the indoor space and air velocity. Understanding this is key to reaching a sound methodology for control. The case studies consist of two main groups: the first group is research based published prior to the onset of the pandemic, and the second group is based on studies of actual infection cases subsequent to the onset of the pandemic. When examining the cases, it is apparent that the three main factors that are constantly recurrent are population density, airflow rate and air recirculation. In a lot of cases, air stagnation and lack of air change are conclusive causative factors of infection transmission, while in a couple of cases, it was shown that infective agents can travel more than 3 m, another factor to be taken into consideration. When there is a total lack of airflow and air change, population density becomes the main causative factor. This research presents a set of guidelines for the ventilation of spaces in different types of indoor environment through exploring the role of the built environment in the transmission of infection and how building design can effect change on public health.

Unlocking Opportunities for Mycobacterium leprae and Mycobacterium ulcerans.

In the recent decade, scientific communities have toiled to tackle the emerging burden of drug-resistant tuberculosis (DR-TB) and rapidly growing opportunistic nontuberculous mycobacteria (NTM). Among these, two neglected mycobacteria species of the Acinetobacter family, Mycobacterium leprae and Mycobacterium ulcerans, are the etiological agents of leprosy and Buruli ulcer infections, respectively, and fall under the broad umbrella of neglected tropical diseases (NTDs). Unfortunately, lackluster drug discovery efforts have been made against these pathogenic bacteria in the recent decade, resulting in the discovery of only a few countable hits and majorly repurposing anti-TB drug candidates such as telacebec (Q203), P218, and TB47 for current therapeutic interventions. Major ignorance in drug candidate identification might aggravate the dramatic consequences of rapidly spreading mycobacterial NTDs in the coming days. Therefore, this Review focuses on an up-to-date account of drug discovery efforts targeting selected druggable targets from both bacilli, including the accompanying challenges that have been identified and are responsible for the slow drug discovery. Furthermore, a succinct discussion of the all-new possibilities that could be alternative solutions to mitigate the neglected mycobacterial NTD burden and subsequently accelerate the drug discovery effort is also included. We anticipate that the state-of-the-art strategies discussed here may attract major attention from the scientific community to navigate and expand the roadmap for the discovery of next-generation therapeutics against these NTDs.

Positive Blood Culture Results Predominantly Unrevealed among Adults Patients with Sepsis

Sepsis is increasing every year and can be life-threatening. In the diagnosis of sepsis, it is challenging to identify the causative agent of infection. This research aims to determine the proportion of positive blood culture in sepsis patients at Hasanuddin University Hospital, Makassar. Blood cultures were collected from 98 adult patients with sepsis manifestations. This research design is cross-sectional with a descriptive observation approach. The data analysed in descriptive statistics were utilised to summarise patient demographics, treatments, and outcomes. Thirteen of 98 samples were positive for microbial pathogens (13.26%). The elderly group had the highest percentage (76.5%); eighty-seven patients (88.77%) were treated with antibiotic therapy prior to blood culture collection. Cephalosporins are the most administered antibiotics (72.4%). Administration of empirical therapy prior to blood culture collection may decrease the sensitivity of culture results. The culture of the infectious focus should be done to assist in the consideration of antimicrobial treatment.

Dermatophytes and ringworm infection

For both people and animals, superficial fungal infections affecting the keratinized layers of skin and its appendages are usually referred to as "ringworm." All layers of the skin can be penetrated by ringworm fungi, or dermatophytes, although they are usually limited to cornified areas of the skin “stratum corneum”. Dermatophytosis is the name for a medical condition caused by dermatophytes. Virtually, there is no human population free from these mycotic diseases and about 25% of the world population are infected by derrmatophytosis. Three genera, Microsporum, Epidermophyton, and Trichophyton (Fungi Imperfecti) in Hyphomycetes, the anamorphic class of the Deuteromycota, are the causative agents of dermatophytosis. Trichophyton rubrum appears to be the most common causative agent of ringworm infections, followed by Trichophyton interdigitale and Microsporum canis. It is critical to advance our understanding of fungal biology and pathology and to raise public awareness of the importance of these infections by providing accurate epidemiological data. Ecological groupings, pathogenic potential, clinical manifestation and therapy “chemical and natural” for dermatophytosis are reviewed.

Estimation of Optimal Lock-Down and Vaccination Rate of a Stochastic SIR Model: A Mathematical Approach

This paper utilizes a stochastic Susceptible-Infected-recovered (SIR) model with a nonlinear incidence rate to estimate the optimal lock-down intensity and vaccination rate under the COVID-19 pandemic environment. We use a Feynman-type path integral control approach to determine a Fokker-Plank type equation of this system. Since we assume the availability of information on the COVID-19 pandemic is complete and perfect, we show the existence of a unique fixed point. A non-linear incidence rate is used because, it can be raised from saturation effects that if the proportion of infected agents is very high so that exposure to the pandemic is inevitable, then the transmission rate responds slower than linearity to the increase in the number of infections. The simulation study shows that with higher diffusion coefficients susceptible and recovery curves keep the downward trends while the infection curve becomes ergodic. Finally, we perform a data analysis using UK data at the beginning of 2021 and compare it with our theoretical results.

Genetic characteristics and potential pathogenic agents in Campylobacter upsaliensis based on genomic analysis

ABSTRACT Campylobacter upsaliensis was the most common Campylobacter species in pets’ gastrointestinal tracts and has been isolated from patients with bacteremia, hemolytic-uremic syndrome, spontaneous abortion, and Guillain-Barré syndrome. However, the genetic characteristics and the full extent of its significance as a human pathogen remain to be fully understood. This study involved an investigation for genomic analysis of 154 strains from different sources and additional antimicrobial resistance profiles of 26 strains for this species. The genomes contained 1,558–1,971 CDS and the genome sizes were estimated to vary from 1.53 Mb to 1.86 Mb, with an average GC content of 34.71%. The entire analyzed genomes could be divided into three clades (A, B, and C) based on ANI and phylogenomic analysis. Significantly, nearly all strains in Clade B were isolated from patient samples, and the virulence-related sequences FlgD, GmhA, and CdtC might serve as determining factors for the classification of Clade B. Half of the tested isolates had MIC values over 64 μg mL−1 for nalidixic acid, gentamicin, and streptomycin. Isolates from pets in China carried more resistant elements in the genomes. This study both provided a comprehensive profile of C. upsaliensis for its genomic features and suggested some pathogenic agents for human infection with this species.

Identification of novel serological agents for porcine deltacoronavirus infection based on the immunogenic accessory protein NS6

Porcine deltacoronavirus (PDCoV) is a swine enteropathogenic CoV that causes severe vomiting, diarrhea and dehydration in suckling piglets, leading to economic losses in the swine industry. There is a great need for a convenient method to detect circulating antibodies and help in accurate diagnosis and disease control. Previously, we demonstrated that a unique PDCoV accessory protein, NS6, is expressed during PDCoV infection in pigs and is incorporated into PDCoV virions; thus, we deduced that NS6 is likely an immunogenic target that can be used for the diagnosis of PDCoV infection. In this study, we first confirmed that NS6 is immunogenic in PDCoV-infected pigs by performing a serum western blot. Furthermore, we developed a novel NS6-based indirect enzyme-linked immunosorbent assay (iELISA) method and compared it to an established S1-based iELISA for the survey of anti-PDCoV IgG or IgA in pigs of different ages in China. The NS6-iELISA has high specificity for the detection of IgG antibodies and no cross-reactivity with other porcine enteric CoVs (transmissible gastroenteritis coronavirus, porcine epidemic diarrhea virus, or swine acute diarrhea syndrome coronavirus). This NS6 serology-based method has great sensitivity and good repeatability, making it a new and cost-saving option for the rapid diagnosis and immunosurveillance of PDCoV, which may also be important for the prevention and control of deltacoronavirus-related infection in pigs and other animals.

Ralstoniapickettii bloodstream infection in the patient with Guillain-Barre syndrome under plasmapheresis

Ralstonia pickettii is a rare Gram-negative opportunistic bacterium that causes rare infections such as bacteremia, neonatal sepsis, endocarditis, and meningitis in hospitalized or immunocompromised patients. In this study, we identified and reported bloodstream infection caused by R. pickettii in a 15 -year-old boy patient with an autoimmune disease, Guillain-Barré syndrome, under plasmapheresis and intravenous immune globulin (IVIG) therapy. He was referred for admission to the neurology center of the teaching hospital of Shiraz, Iran for inability to walk, and lower extremity muscle weakness. After he was treated with plasmapheresis once during hospitalization, and after severe fever besides shivering blood cultures using BACT/ALERT®3D instrument were positive for R. pickettii.According to antibiotic susceptibility test reports, Ciprofloxacin (5 μg) was prescribed. Fortunately, after starting antibiotic treatment, blood culture results reported no growth after 5 days. Indeed, the patient was infected with nosocomial hepatitis A and URSOBIL (300 mg/BID/Po) was administered. Hence, after reporting the infection occurrence to the hospital infection control unit, initial and possible measures such as device infection control, replacement of potentially polluted plasmapheresis fluids, disinfecting the environment and replacing old sterile washing water with new sources were carried out in plasmapheresis unit. In conclusion, R. pickettii is a rare nosocomial infection that is responsible for the contamination of medical equipment, especially in hemodialysis, plasmapheresis devices and sterile solutions. Also, it is suggested that the role and importance of rare environmental bacteria as the causative agents of human infections should not be ignored in medical centers.

Rare Cause of Soft Tissue Infection: Shewanella algae

Abstract Shewanella algae is a common microorganism in nature, but a rare pathogen in humans. It is a causative agent of skin and soft tissue infections, especially in patients with skin ulcers or trauma. S. algae can enter the body through the eyes, ears, gastrointestinal tract, or respiratory tract. Immunocompromised individuals are at increased risk of developing bacteremia and sepsis from the infection. This report presents a case of posttraumatic soft tissue infection caused by S. algae in an 18-year-old male after swimming in the sea. The bacteria were cultured from the wound site.

Inducible Clindamycin Resistance in Staphylococcus aureus Isolates in Kermanshah, Iran

Background: Staphylococcus aureus is the most common agent of nosocomial infections. Macrolide Lincosamide-Streptogramin B (MLSB) antibiotics are the therapeutic choices for treatment of infections due to methicillin resistant S. aureus (MRSA) isolates. The most frequent mechanism for inducible resistance in S. aureus is modification in target site by erm (erythromycin ribosome methylase) genes. Objectives: The aim of this research was to determine inducible MLSB (iMLSB) and detection the erm genes in clinical samples of S. aureus isolated from hospitalized patients in the Imam Reza hospital of Kermanshah, west of Iran. Methods: This study performed on 126 samples of S. aureus. Identification of isolates were performed using microbiological and biochemical procedures. Inducible resistance to clindamycin was tested by D-test. The prevalence of genes, such as femB, mecA, ermA and ermB was assessed by polymerase chain reaction (PCR). Results: Eighty-three cases (65.9%) of isolates were methicillin resistant S. aureus (MRSA). The resistance rate against erythromycin and clindamycin was 67.4% and 52.2%, respectively. Totally, 49 cases (38.9%) of isolates were resistant to both erythromycin and clindamycin indicating constitutive MLSB phenotype (cMLSB); 20 cases (15.9%) isolates showed positive D test indicating inducible MLSB phenotype (iMLSB), while 16 cases (12.7%) were negative for D test indicating MS phenotype. Among 20 cases with iMLSB phenotype, ermC and ermA genes were showed in 7 cases (35%) and 4 cases (20%) isolates, respectively. The ermB gene is not detected in any cases and 9 cases (45%) isolates did not have any erm genes. Conclusions: In general, findings of this study showed high frequency of resistance to clindamycin and erythromycin among S. aureus isolates and cMLSB to be the most pattern phenotype and ermC gene is the most common gene in iMLSB phenotype. Because variation of antimicrobial resistance pattern in geographic regions obtaining local results is useful for detecting and more appropriate control of nosocomial infection due to S. aureus isolates.

Exosomes derived from bladder epithelial cells infected with uropathogenic Escherichia coli increase the severity of urinary tract infections (UTIs) by impairing macrophage function.

Uropathogenic Escherichia coli (UPEC) is the primary causative agent of urinary tract infections (UTIs) in humans. Moreover, as one of the most common bacterial pathogens, UPEC imposes a substantial burden on healthcare systems worldwide. Epithelial cells and macrophages are two major components of the innate immune system, which play critical roles in defending the bladder against UPEC invasion. Yet, the routes of communication between these cells during UTI pathogenesis are still not fully understood. In the present study, we investigated the role of membrane-bound nanovesicles (exosomes) in the communication between bladder epithelial cells and macrophages during UPEC infection, using an array of techniques such as flow cytometry, miRNA profiling, RNA sequencing, and western blotting. Moreover, our in vitro findings were validated in a mouse model of UPEC-induced cystitis. We found that UPEC infection induced the bladder epithelial MB49 cell line to secrete large numbers of exosomes (MB49-U-Exo), which were efficiently absorbed by macrophages both in vivo and in vitro. Assimilation of MB49-U-Exo induced macrophages to produce proinflammatory cytokines, including tumor necrosis factor (TNF)α. Exposure of macrophages to MB49-U-Exo reduced their phagocytic activity (by downregulating the expression of phagocytosis-related genes) and increased their rate of apoptosis. Mechanistically, we showed that MB49-U-Exo were enriched in miR-18a-5p, which induced TNFα expression in macrophages by targeting PTEN and activating the MAPK/JNK signaling pathway. Moreover, administration of the exosome secretion inhibitor GW4869 or a TNFα-neutralizing antibody alleviated UPEC-mediated tissue damage in mice with UPEC-induced cystitis by reducing the bacterial burden of the bladder and dampening the associated inflammatory response. Collectively, these findings suggest that MB49-U-Exo regulate macrophage function in a way that exacerbates UPEC-mediated tissue impairment. Thus, targeting exosomal -release or TNFα signaling during UPEC infection may represent promising non-antibiotic strategies for treating UTIs.

Impact of airborne algicidal bacteria on marine phytoplankton blooms.

Ocean microbes are involved in global processes such as nutrient and carbon cycling. Recent studies indicated diverse modes of algal-bacterial interactions, including mutualism and pathogenicity, which have a substantial impact on ecology and oceanic carbon sequestration, and hence, on climate. However, the airborne dispersal and pathogenicity of bacteria in the marine ecosystem remained elusive. Here, we isolated an airborne algicidal bacterium, Roseovarius nubinhibens, emitted to the atmosphere as primary marine aerosol (referred also as sea spray aerosols) and collected above a coccolithophore bloom in the North Atlantic Ocean. The aerosolized bacteria retained infective properties and induced lysis of Gephyrocapsa huxleyi cultures.This suggests that the transport of marine bacteria through the atmosphere can effectively spread infection agents over vast oceanic regions, highlighting its significance in regulating the cell fate in algal blooms.

Modulation of Staphylococcus aureus Biofilm Formation through Subinhibitory Concentrations of Biogenic Silver Nanoparticles and Simvastatin

Staphylococcus aureus is a causative agent of nosocomial infections and its antibiotic-resistant strains give cause for concern. Solutions are being explored to improve treatment for these infections, including repositioning drugs such as statins and using nanoparticles with antimicrobial properties. This study evaluated the antimicrobial effects of simvastatin (SIM) and biologically synthesized silver nanoparticles (bio-AgNPs) in isolate form and in combination using assays of minimum inhibitory concentration (MIC), an in vitro biofilm model, and the association of antimicrobials against clinical strains of S. aureus. Bio-AgNPs showed a 53.8 ± 1.23 nm mean diameter and standard deviation, a 0.23 polydispersity index, and a −25.66 ± 2.19 mV mean potential and standard deviation. Transmission electron microscopy confirmed the formation of nanoparticles, and the presence of Ag0 and AgCl. S. aureus strains were sensitive to bio-AgNPs and SIM, showing 31.88–187.5 and 74.66–149.32 μM concentrations, respectively. The association assay showed 2.0 fractional inhibitory concentration indices (i.e., indifferent for clinical strains) and 0.32 values for the standard ATCC 29213 strain (synergy). Biofilm inhibition assays with isolated SIM and bio-AgNPs showed decreased biofilm formation 4× to ⅛ MICs concentrations, showing no synergism in association. These findings evince that simvastatin and bio-AgNPs at subinhibitory concentrations can serve as antimicrobial agents against S. aureus biofilm.

Double-Stranded RNA Targeting White Mold Sclerotinia sclerotiorum Argonaute 2 for Disease Control via Spray-Induced Gene Silencing.

Sclerotinia sclerotiorum, the causal agent of white mold infection, is a cosmopolitan fungal pathogen that causes major yield losses in many economically important crops. Spray-induced gene silencing has recently been shown to be a promising alternative method for controlling plant diseases. Based on our prior research, we focused on developing a spray-induced gene silencing approach to control white mold by silencing S. sclerotiorum argonaute 2 (SsAgo2), a crucial part of the fungal small RNA pathway. We compared the lesion size as a result of targeting each ∼500-bp segment of SsAgo2 from the 5' to the 3' end and found that targeting the PIWI/RNaseH domain of SsAgo2 is most effective. External application of double-stranded RNA (dsRNA)-suppressed white mold infection using either in vitro or in vivo transcripts was determined at the rate of 800 ng/0.2 cm2 area with a downregulation of SsAgo2 from infected leaf tissue confirmed by RT-qPCR. Furthermore, magnesium/iron-layered double hydroxide nanosheets loaded with in vitro- and in vivo-transcribed dsRNA segments significantly reduced the rate of S. sclerotiorum lesion expansion. In vivo-produced dsRNA targeting the PIWI/RNaseH domain of the SsAgo2 transcript showed increased efficacy in reducing the white mold symptoms of S. sclerotiorum when combined with layered double hydroxide nanosheets. This approach is promising to produce a large scale of dsRNA that can be deployed as an environmentally friendly fungicide to manage white mold infections in the field.

Challenges for developing bacterial CA inhibitors as novel antibiotics.

Acetazolamide, methazolamide, ethoxzolamide and dorzolamide, classical sulfonamide carbonic anhydrase (CA) inhibitors (CAIs) designed for targeting human enzymes, were also shown to effectively inhibit bacterial CAs and were proposed for repurposing as antibacterial agents against several infective agents. CAs belonging to the α-, β- and/or γ-classes from pathogens such as Helicobacter pylori, Neisseria gonorrhoeae, vacomycin resistant enterococci (VRE), Vibrio cholerae, Mycobacterium tuberculosis, Pseudomonas aeruginosa and other bacteria were considered as drug targets for which several classes of potent inhibitors have been developed. Treatment of some of these pathogens with various classes of such CAIs led to an impairment of the bacterial growth, reduced virulence and for drug resistant bacteria, a resensitization to clinically used antibiotics. Here I will discuss the strategies and challenges for obtaining CAIs with enhanced selectivity for inhibiting bacterial versus human enzymes, which may constitute an important weapon for addressing the drug resistance to β-lactams and other clinically used antibiotics.