Opportunistic Infections Research Articles

Irrigation Scheduling Impacts Vegetative Growth, Seed Yield, and Fungal Diseases of Spinach Seed Crops in a Maritime Mediterranean Climate

Although irrigation scheduling has been studied for diverse vegetable crops, much less attention has been given to irrigation scheduling for the seed crops on which these production systems rely. In spinach, for which irrigation scheduling needs are likely to vary greatly between seed and leaf production, this leaves seed producers without adequate resources to make irrigation scheduling decisions. Our research sought to fill this gap by evaluating two alternative irrigation scheduling strategies (a publicly available decision-support tool and soil moisture sensors) and four soil moisture thresholds for irrigation for their impacts on vegetative growth, marketable seed yield, seed quality, and the severity of Stemphylium leaf spot (caused by Stemphylium vesicarium and Stemphylium beticola), a common foliar disease of spinach, under sprinkler irrigation. We found that in all 3 years of the study, earlier and more frequent irrigation increased vegetative growth. However, marketable seed yield only increased relative to the control treatment based on farmers’ standard irrigation practices in 1 of the 3 years—a year with an abnormally late planting date. This indicates that vegetative growth is more responsive than seed yield to earlier and more frequent irrigation, and that increases in vegetative growth do not translate directly to increased marketable seed yield. Contrary to the expected increase in Stemphylium leaf spot severity with increasing irrigation, the severity decreased in both years it was measured, likely as a result of the small stature of the spinach seed parent lines used in our study and opportunistic pathogenicity on moisture-stressed plants. These results provide a useful foundation from which spinach seed producers can make irrigation management decisions for their crops that underpin a valuable global industry.

Multiple Myeloma: A Review of the Literature and a Case Report Highlighting the Immunocompromised State of Myeloma Patients.

Multiple myeloma (MM), a malignancy involving plasma cells, disproportionately affects older adults with an average age of diagnosis of about 70 years. Oftentimes, the therapies used in the treatment of MM are associated with a risk for immunotoxicity, lowering the ability of the immune system to fight off opportunistic infections. This is an important relationship for clinicians to realize as the incidence of opportunistic infections in myeloma patients is increasing. As an example, we present a case of a patient with MM who subsequently developed a cryptococcal infection. Our paper will highlight the key details of the case as well as shed light on the importance of understanding the immunodeficiencies in this patient population. We highlight important aspects of the current literature related to MM and relate them to the associated case.

Advances in Mechanism of HIV-1 Immune Reconstitution Failure: Understanding Lymphocyte Subpopulations and Interventions for Immunological Nonresponders.

In individuals diagnosed with AIDS, the primary method of sustained suppression of HIV-1 replication is antiretroviral therapy, which systematically increases CD4+ T cell levels and restores immune function. However, there is still a subset of 10-40% of people living with HIV who not only fail to reach normal CD4+ T cell counts but also experience severe immune dysfunction. These individuals are referred to as immunological nonresponders (INRs). INRs have a higher susceptibility to opportunistic infections and non-AIDS-related illnesses, resulting in increased morbidity and mortality rates. Therefore, it is crucial to gain new insights into the primary mechanisms of immune reconstitution failure to enable early and effective treatment for individuals at risk. This review provides an overview of the dynamics of key lymphocyte subpopulations, the main molecular mechanisms of INRs, clinical diagnosis, and intervention strategies during immune reconstitution failure, primarily from a multiomics perspective.

Disasters pile up on the rubbing heel: Sporothrix globosa as secondary infection to Mycobacterium chelonae infection

Mycobacterium chelonae and Sporothrix globosa, both of which are opportunistic pathogens, have been proved to be possible multidrug resistant. However, are all recurring symptoms in chronic infections related to decreasing susceptibility? Here we report a case of sporotrichosis secondary to M. chelonae infection. In addition, we find that the blackish-red spots under the dermoscopic view can be employed as a signal for the early identification and regression of sub-cutaneous fungal infection.

ENTEROCOCCUS FAECALIS AS AN ETIOLOGICAL FACTOR OF PURULENT PROCESSES IN SURGICAL PATIENTS: ANALYSIS OF BACTERIOLOGICAL RESEARCH RESULTS

Introduction. Opportunistic infections are often caused by microorganisms that are part of the normal human body microflora. Studying the role of microbiota in infectious pathology and the mechanisms of interaction between opportunistic microorganisms in microbial associations is crucial. Enterococcus faecalis is one such microorganism found in bacterial associations. The purpose of this study was to investigate the frequency of detecting E. faecalis in monoculture and as part of associations, the qualitative and quantitative composition of these associations, and the analysis of the variability in the pathogen’s susceptibility to antibiotics. Results and discussion. Out of 123 samples studied, Enterococcus bacteria were cultured in 38 cases, accounting for 30.9%. E. faecalis was isolated in monoculture in only 24.2% of all cultures of this species. Moreover, it was isolated in clinically significant concentrations (≥105 bacterial cells per 1 ml of the studied material) in only four out of eight cases. There is a difference in the susceptibility of cultures for groups of isolates where the concentration of microorganisms in the test material is <105 and ≥105 microbial cells per 1 ml. Conclusion. E. faecalis was present in 26.8% of isolates obtained from patients in the surgical department with purulent-inflammatory diseases. E. faecalis is mainly found in microbial associations. The susceptibility of E. faecalis to most of the antibiotics used in the study is higher in the group of isolates where this species of microorganism was present in concentrations equal to or higher than 105 microbial cells per 1 ml of the test material.

Widespread form of Majocchi's granuloma in a kidney transplant recipient.

Kidney transplantation is the encouraged kidney replacement therapy due to providing more prolonged survival with a better quality of life. Unfortunately, kidney transplant recipients are susceptible to infections because of long-term utilization of immunosuppression. Despite dermatophyte infections are generally not life-threatening, the clinical significance has been recently enhanced by an increasing number of immunocompromised patients. We have presented a rare dermatophytosis course, Majocchi's granuloma, that spreads to all extremities during the early post-transplant period. A young kidney transplant recipient was exposed to intensive immunosuppression therapy due to acute rejection in the early period of post-transplantation. After four months, numerous nodular skin lesions were raised on various body parts. An invasive fungal infection was identified in the skin biopsy. Also, Trichophyton rubrum was isolated in the tissue cultures. Consequently, the patient was diagnosed with Majocchi's granuloma. An effectual treatment was attained with an oral terbinafine tablet. Majocchi's granuloma is a distinct form of dermatophytosis characterized by the spreading of infection into the dermis. In this unexpected case, we alerted physicians to opportunistic infections in the kidney transplant recipient.

Drug Persistence and Incidence of Active Tuberculosis of Tumor Necrosis Factor Alpha Inhibitors Versus Tocilizumab as the First-Line Biological Treatment in Patients with Rheumatoid Arthritis: A Nationwide Population-Based Retrospective Cohort Analysis.

Drug persistence may be a surrogate marker that reflects both long-term efficacy and safety in clinical settings, and tuberculosis (TB) is considered as one of the most important opportunistic infections after the biological treatment in rheumatoid arthritis (RA). We aimed to compare drug persistence and incidence of TB between tumor necrosis factor alpha (TNFα) inhibitors and tocilizumab in patients with RA using data from the Korean Health Insurance Review and Assessment Service database. In this analysis, 5449 patients with RA who started TNFα inhibitors, such as adalimumab, etanercept, infliximab, and golimumab or tocilizumab, as the first-line biological therapy between January 2014 and December 2017 were analyzed and followed up until December 2019. Drug persistence was defined as the duration from initiation to first discontinuation, and TB was defined as the prescription of > 2 anti-TB medications after the initiation of biologics. TNFα inhibitors and tocilizumab were prescribed in 4202 (adalimumab, 1413; etanercept, 1100; infliximab, 769; golimumab 920) and 1247 patients with RA, respectively. During the analysis period, 2090 (49.7%) and 477 (38.3%) patients with RA discontinued TNFα inhibitors and tocilizumab, respectively, and 42 patients with RA developed TB (TNFα inhibitors, 33; tocilizumab, 9). After adjustment for confounding factors, TNFα inhibitors were significantly associated with a higher risk of discontinuation compared with tocilizumab (hazard ratio (HR) 1.63, p < 0.001). In subgroup analysis, all types of TNFα inhibitors, except for infliximab, demonstrated a significantly lower persistence rate compared with tocilizumab. There was no significant difference in TB incidence between tocilizumab and TNFα inhibitors. In subgroup analysis, infliximab has a significantly higher risk of TB compared with tocilizumab (HR2.84, p = 0.02). In this analysis, tocilizumab had longer persistence than TNFα inhibitors with a similar incidence of TB. Our analysis has limitations: (1) The HIRA database lacks clinical details like disease activity and joint damage extent, potentially influencing the analysis results. (2) Reasons for discontinuing biological agents were not available. (3) TB diagnoses may be inaccurate because of missing microbiological results. (4) We did not analyze the impact of treating latent TB infection on TB development post-biological treatment, despite mandatory screening in Korea.

Biologics Versus JAK Inhibitors. Part I: Cancer Risk. A Narrative Review.

Biological drugs (BD) and Janus kinase inhibitors (JAKi) have revolutionized the treatment of diverse dermatoses. However, there are concerns regarding their safety, especially the risk of cancer and opportunistic infections. Here, we discuss the risk of cancer associated with the BD and JAKi used in dermatology. A narrative review was carried out. All relevant articles evaluating the risk of cancer associated with BD or JAKi and published between January 2010 and February 2024 were selected. Multiple large studies have evaluated the association between BD, JAKi and cancer risk. However, there is a lack of prospective, comparative studies. Overall, patients undergoing BD and JAKi present a cutaneous cancer incidence similar to that in the general population. The drugs more strongly associated with non-skin cancer risk were anti-tumor necrosis factor (anti-TNFs) agents and JAKi (especially tofacitinib and oral ruxolitinib). This risk appears to increase with age, the presence of other factors (such as chronic immunosuppression from previous drugs or other comorbidities), and specific diseases such as rheumatoid arthritis (RA) and myelodysplastic syndrome. Conversely, BD such as interleukin (IL)-17 and IL-23 inhibitors may even reduce the risk of some visceral and hematological malignancies. In patients with dermatological conditions such as psoriasis and atopic dermatitis, the risk of malignancies may be lower than in other subgroups, and probably comparable to the general population. The incidence of cancer in patients undergoing BD or JAKi is generally low. This incidence can be higher in elderly patients with RA or myelodysplastic syndrome, and in those undergoing prolonged therapy with tofacitinib or ruxolitinib (oral), or anti-TNF agents.

Pneumocystis murina lesions in lungs of experimentally infected Cd40l-/- mice.

The Cd40l-/- mouse is a well-established model of X-linked hyper-immunoglobulin M (IgM) syndrome, an immunodeficiency disorder of human beings characterized by the lack of expression of the CD40 ligand (CD40L) on activated T-cells, predisposing to infections with opportunistic pathogens like Pneumocystis jirovecii. The aim of our study was to describe the pulmonary lesions in Cd40l-/- mice experimentally infected with Pneumocystis murina, in comparison with naturally infected severe combined immunodeficient (SCID) mice. Formalin-fixed paraffin-embedded lungs from 26 Cd40l-/-, 11 SCID, and 5 uninfected Cd40l-/- mice were examined by histology and immunohistochemistry for the presence of the pathogen and for leukocyte populations (CD3, CD4, CD45R/B220, CD8a, Iba-1, Ly-6G, CD206, MHC II, and NKp46/NCR1). Infection was confirmed by immunohistochemistry in 18/26 (69%) Cd40l-/- mice and in 11/11 (100%) SCID mice. Fourteen out of 26 (54%) Cd40l-/- mice had interstitial pneumonia. Twenty-three out of 26 (88%) Cd40l-/- mice had peribronchiolar/perivascular lymphoplasmacytic infiltrates, rich in B-cells and Mott cells. Acidophilic macrophage pneumonia was additionally found in 20/26 (77%) Cd40l-/- mice. Only 4/11 (36%) SCID mice had interstitial pneumonia, but no peribronchiolar/perivascular infiltrates or acidophilic macrophage pneumonia were observed in this strain. This study represents the first description of pulmonary histopathological lesions in Cd40l-/- mice infected with P. murina. We speculate that the singular characteristics of the inflammatory infiltrates observed in Cd40l-/- mice could be explained by the specific immune phenotype of the model.

Molecular Screening for Digital Dermatitis-Associated Treponemes in Bovine Ischaemic Teat Necrosis Lesions and Milk in Dairy Cattle

Bovine ischaemic teat necrosis (ITN) is a disease affecting the skin of the teats of dairy cows with an unknown aetiopathogenesis. Digital dermatitis (DD)-associated treponemes have previously been suggested as a potential aetiological agent in ITN, although the sample size was small. The current study, using established PCR techniques, aimed to examine the association with the presence of DD-associated treponemes in a large number of ITN samples from a wider geographical area, and surveyed the potential of milk as an infection reservoir. From 95 ITN lesions, 35.8% (n = 34) were positive for at least one DD-associated treponeme compared with only 5.6% (n = 1) of 18 non-lesioned teats from cows with ITN lesions on a different teat using a nested PCR approach. All 10 age- and production-matched control cows were negative for DD-associated treponemes via PCR. No DD-associated treponemes could be detected from foremilk of cows with (n = 19) and without (n = 31) a DD lesion on the hind feet. DD-associated treponemes could be detected via PCR after incubation in milk for up to 2 h. Therefore, milk does not appear to be a competent reservoir for transmission of DD-associated treponemes. Moreover, in the current study DD-associated treponemes were only detected in a subset of ITN samples, so it is unlikely these opportunistic skin-associated pathogens are the major or sole agent of ITN.

Understanding the Role of Candida Abicans in the Development of Cancer Cells, its Progression Mechanism, Possible Preventive Measures and Treatment

As a common human commensal fungus, Candida albicans may play an active part in cancer progression rather than just being present by chance in people who have cancer. A lot of research has shown that having Candida albicans in your body can make you more likely to get oral, esophageal, intestinal, and maybe even skin cancers. But more research needs to be done to find out exactly how this opportunistic pathogen adds to the development of cancer. The purpose of this review is to summarize the current data and possible ways that Candida albicans may be linked to cancer. The fungus may help tumors grow by using its cytochrome system to make DNA-damaging benzopyrene molecules. In addition, it can change the immune system by causing inflammation while blocking antitumor reactions. Candida albicans is a dimorphic fungus, which means it can change between yeast forms with only one cell and hyphal forms that invade host cells and help them spread. The pathogen may be protected by its biofilms, which may change the native microbiota makeup in ways that make people more likely to get cancer. Infected tissues could also have oncogenic signaling turned on by fungus virulence factors. Assuming that the link between Candida and cancer is a direct one, Candida albicans could be a useful way to tell which people are most likely to get cancer. Taking aim at the fungus is also a fresh way to make present cancer treatments better. But well-planned prospective clinical studies are still needed to make sure that the results of research on associations and animal models are correct. Getting clear on the molecular processes will help us understand how tumors grow and find new ways to treat them that focus on how the host and pathogen interact.

Landscape of invasive fusariosis in pediatric cancer patients: Results of a multicenter observational study from Latin America

Abstract Invasive fusariosis (IF) is a life-threatening opportunistic infection that affects vulnerable hosts. We conducted a multicenter and multinational retrospective study to characterize the natural history and clinical management of IF in pediatric cancer patients. We selected patients under 18 years who were sequentially hospitalized in ten Latin American medical centers with a diagnosis of IF between 2002 and 2021. Data were collected using an electronic case report form complemented by a dictionary of terms. We assessed mortality at 30, 60, and 90 days. We collected data from 60 episodes of IF (median age of 9.8 years) that were mostly documented in hematologic malignancies (70%). Other risk conditions found were lymphopenia (80%), neutropenia (76.7%), and corticosteroid exposure (63.3%). IF was disseminated in 55.6% of patients. Skin lesions was present in 58.3% of our patients, followed by pulmonary involvement in 55%, sinusitis in 21.7%, bone/joint in 6.7% and one case each of endocarditis and brain abscess. Positive blood and skin biopsy cultures were detected in 60% and 48.3% of cases, respectively. Fusarium solani complex was the most commonly identified agent (66.6%). The majority of patients received monotherapy within the first 72h hours (71.6%), either with voriconazole or amphotericin B formulation. The mortality rates at 30, 60, and 90 days were 35%, 41.6% and 45%, respectively. Important factor impacting mortality appears to be disseminated disease. The high percentage of patients with fungal involvement in multiple organs and systems highlights the need for extensive work-up for additional sites of infection in severely immunocompromised children.

Rapid detection of virulence-related genes by multiplex PCR in five pathogenic bacteria of mulberry bacterial wilt

Mulberry bacterial wilt is a devastating disease that is difficult to control and causes serious economic losses to the sericulture industry. This disease is mostly caused by a diverse group of pathogenic and opportunistic bacteria including, Ralstonia pseudosolanacearum, Pantoea ananatis, Enterobacter cloacae complex (ECC), Klebsiella pneumoniae species complex (KpSC), and K. oxytoca complex (KoC). Due to the lack of a rapid and reliable test to simultaneously detect these complex pathogens of mulberry wilt, we developed a multiplex PCR (mPCR) assay to detect five virulence-related genes carried by the pathogenic bacteria of mulberry bacterial wilt disease. The primers were designed for the virulence-related genes: pleD (GGDF structural domain-containing protein), yjfP (esterase), pelY (peripheral pectate lyase), ampD (N-acetyl-anhydromuranmyl-L-alanine amidase), and ripW (type III effector). Overall, the developed mPCR assay showed highly specific, sensitive and reproducible detection of target pathogens. Briefly, the results showed that the mPCR was highly specific in individual reactions, and the lowest detection concentration of the five pathogenic bacteria was 1.87 × 103 CFU/mL (DNA = 2.45 pg/μL). From 46 natural mulberry wilt samples, the mPCR detection rates of P. ananatis, ECC, KpSC, KoC and R. pseudosolanacearum were 8.69, 91.3, 34.7, 23.9 and 65.21%, respectively. The traditional culture media isolation methods showed comparable results. The pathogenicity test of 84 suspected pathogenic bacteria revealed that the morbidity (average morbidity level) caused by the pathogenic bacteria detected by mPCR was ≥ 65.5%, while the morbidity of the undetected pathogenic bacteria was ≤ 35.5%. Based on these results, we believe that the mPCR developed in the present study will be useful in rapid, reproducible, and sensitive detection of the pathogenic bacteria causing mulberry bacterial wilt including, R. pseudosolanacearum, P. ananatis, ECC, KpSC, and KoC.Graphical abstract

PREVENTION OF INTESTINAL INFECTIONS OF BACTERIAL ETIOLOGY IN PIGS

Intestinal infections of bacterial etiology are among the most common diseases in pigs of different age groups. Healthy gastrointestinal tract is the basis for successful pig farming. Therefore, the prevention and control of major gastrointestinal infections is a key to farm profitability. Intestinal infections are caused by both pathogenic and opportunistic pathogenic bacteria. The most common diseases caused by pathogenic microorganisms include dysentery, ileitis and salmonellosis. Their causative agents are the bacteria Brachyspira spp., Lawsonia spp. and Salmonella spp. respectively. The most common opportunistic pathogenic bacteria are: Escherichia coli, Clostridium spp. and Proteus spp. Bacterial intestinal infections are diverse and widespread, and therefore cause significant economic losses for livestock farms. They suffer significant losses due to animal mortality, reduced productivity and, as a result, increased treatment costs. Therefore, the efforts of scientists should be aimed at creating innovative approaches and effective therapeutic agents that would not only treat but also prevent bacterial intestinal infections. The article presents data on traditional and innovative approaches to the prevention of bacterial intestinal infections in pigs. The advantages of using feed additives for the prevention and treatment of bacterial intestinal infections in pigs are described.

The genes mgtE and spoVG are involved in zinc tolerance of Staphylococcus aureus.

Staphylococcus aureus is an opportunistic pathogen causing tremendous public health burden and high mortality in invasive infections. Treatment is becoming increasingly difficult due to antimicrobial resistances. The use of metals in animal husbandry and aquaculture to reduce bacterial growth and subsequent acquisition of metal resistances has been shown to co-select for antimicrobial resistance. Therefore, understanding adaptive mechanisms that help S. aureus to survive metal exposure is essential. Using a screening approach, we were able to identify two genes encoding the transporter MgtE and the transcriptional regulator SpoVG, which conferred increased tolerance to specific metals such as zinc when inactivated. Further testing showed that the deletion of mgtE leads to reduced intracellular zinc levels, suggesting a role in zinc uptake. The accumulation of mutations in these genes when exposed to other metals suggests that inactivation of these genes could be a common mechanism for intrinsic tolerance to certain metals.

Paint It Black: Staining of the Yeast Cryptococcus Neoformans with India Ink

Aims: To rectify the application of negative staining using India Ink dye in order to visualize the opportunistic yeast, Cryptococcus neoformans and its capsule. Discussion: The yeast C. neoformans is generally considered an opportunistic fungal pathogen due to its propensity to infect immunocompromised hosts, particularly those with HIV (+). This yeast responsible for causing severe disseminated Cryptococcus meningoencephalitis (CM) in humans. The type of clinical sample commonly sent for laboratory analysis of suspected patients is the cerebrospinal fluid (CSF) that usually obtained from spinal tap or lumbar puncture procedure. laboratory analysis to confirm CM initially by direct visualization of Cryptococci via light microscopy. Visualization of capsule, as the hallmark of C. neoformans is easy when appropriate number of yeasts are available in the clinical sample. India Ink is the dye of choice to stain C. neoformans and its capsule. The pathognomonic resemblance of its capsule is that of a halo appearance, whether thin or thick, surrounding the cell made visible by suspending the yeast in India ink preparations. Conclusion: India ink stain is still widely used for the detection of cryptococci in CSF, particularly in resource-limited laboratory/health service. Its sensitivity can be improved.

Associations of plant-based foods, red and processed meat, and dairy with gut microbiome in Finnish adults.

Population-based studies on the associations of plant-based foods, red meat or dairy with gut microbiome are scarce. We examined whether the consumption of plant-based foods (vegetables, potatoes, fruits, cereals), red and processed meat (RPM) or dairy (fermented milk, cheese, other dairy products) are related to gut microbiome in Finnish adults. We utilized data from the National FINRISK/FINDIET 2002 Study (n = 1273, aged 25-64 years, 55% women). Diet was assessed with 48-hour dietary recalls. Gut microbiome was analyzed using shallow shotgun sequencing. We applied multivariate analyses with linear models and permutational ANOVAs adjusted for relevant confounders. Fruit consumption was positively (beta = 0.03, SE = 0.01, P = 0.04), while a dairy subgroup including milk, cream and ice-creams was inversely associated (beta=-0.03, SE 0.01, P = 0.02) with intra-individual gut microbiome diversity (alpha-diversity). Plant-based foods (R2 = 0.001, P = 0.03) and dairy (R2 = 0.002, P = 0.01) but not RPM (R2 = 0.001, P = 0.38) contributed to the compositional differences in gut microbiome (beta-diversity). Plant-based foods were associated with several butyrate producers/cellulolytic species including Roseburia hominis. RPM associations included an inverse association with R. hominis. Dairy was positively associated with several lactic producing/probiotic species including Lactobacillus delbrueckii and potentially opportunistic pathogens including Citrobacter freundii. Dairy, fermented milk, vegetables, and cereals were associated with specific microbial functions. Our results suggest a potential association between plant-based foods and dairy or their subgroups with microbial diversity measures. Furthermore, our findings indicated that all the food groups were associated with distinct overall microbial community compositions. Plant-based food consumption particularly was associated with a larger number of putative beneficial species.

Phytochemicals as Adjuvant Therapies in RND Efflux Mediated Multidrug Resisting Pseudomonas Aeruginosa Infections and Evaluations Techniques of Efflux Inhibitory Activities in Bacteria:

Abstract: One of the top-listed opportunistic pathogens that are frequently found in medical devices such as ventilation systems is Pseudomonas aeruginosa. These bacteria often cause infections in the lungs (pneumonia), blood after surgery, and other parts of the body. Extreme susceptibility to P. aeruginosa infection primarily exists in immunosuppressed individuals, and long-term evolution has led to the development of genetic resistance mechanisms that have high genetic flexibility against damaging antibiotics. Several lines of research evidence point to efflux as the primary reason for the organism's effectiveness against antibiotic treat-ment in infections caused by this bacterium. Drug Efflux pumps play a crucial role in medicine because they expulse a variety of unique and unrelated chemical structures with either antibi-otics or antimicrobials before they reach the concentration necessary to kill bacteria, confer-ring multiple resistance to more than one class of antibiotics. Targeting this mechanism for example by blocking the most active efflux pump MexAB-orpM would probably lead to the discovery of new ways to circumvent the bacterial system of antibiotic resistance and boost treatment effectiveness.

A Label-Free Approach for Relative Spatial Quantitation of c-di-GMP in Microbial Biofilms.

Microbial biofilms represent an important lifestyle for bacteria and are dynamic three-dimensional structures. Cyclic dimeric guanosine monophosphate (c-di-GMP) is a ubiquitous signaling molecule that is known to be tightly regulated with biofilm processes. While measurements of global levels of c-di-GMP have proven valuable toward understanding the genetic control of c-di-GMP production, there is a need for tools to observe the local changes of c-di-GMP production in biofilm processes. We have developed a label-free method for the direct detection of c-di-GMP in microbial colony biofilms using matrix-assisted laser desorption/ionization mass spectrometry imaging (MALDI-MSI). We applied this method to the enteric pathogen Vibrio cholerae, the marine symbiont V. fischeri, and the opportunistic pathogen Pseudomonas aeruginosa PA14 and detected spatial and temporal changes in c-di-GMP signal that accompanied genetic alterations in factors that synthesize and degrade the compound. We further demonstrated how this method can be simultaneously applied to detect additional metabolites of interest from a single sample.

DETERMINATION OF THE SENSITIVITY OF DERMATOMYCOSIS CAUSES TO FUNGICIDES

A microbiological study of the affected areas of the skin of dogs and cats was carried out for the detection of microscopic fungi. The following microscopic fungi were isolated from the pathological material: Candida spp., Aspergillus brasiliensis, Epidermophyton spp., Microsporum spp., Mucor spp., Trichophyton spp., Mallasseria spp., Sporotrich spp. Isolated microscopic fungi of the genus Malassezia spp. belong to the superficial mycoses (keratomycoses) and affect the surface layers of the skin and fur. Epidermatophytes: Trichophyton spp., Epidermophyton spp., Microsporum spp. affect the epidermis, skin, and coat. In addition, opportunistic fungi of the genus Aspergillus brasiliensis were found in the studied samples. It was established that the sensitivity of fungi isolated from the affected areas of the skin of dogs and cats to a 1% solution of ketonazole and clotrimazole is different. In particular, a 1% solution of ketonazole showed significantly higher activity compared to a 1% solution of clotrimazole. Thus, when determining the fungicidal effect of ketonazole, the growth retardation zone of the dermatophyte Trichophyton spp. was 34.3±0.6 mm, and the 1% clotrimazole solution was 21.3±0.3 mm. Ketonazol also showed higher fungicidal activity against the microscopic fungi Aspergillus brasiliensis and Candida spp., compared to clotrimazole. Thus, the activity of ketonazole was, respectively, 55.7 and 48.4% higher compared to clotrimazole. Clotrimazole showed the lowest fungicidal effect on Aspergillus brasiliensis, Mallasseria spp., Mucor spp., and Epidermophyton spp., the growth retardation zones of microscopic fungi were, respectively, 14.3±0.3, 14.3±0.6, 14.6± 0.6 and 16.6±0.3 mm.