Pathogens, Volume 7, Issue 3 (September 2018) – 19 articles

Limited data are available on susceptibilities of these organisms to some of the recently made accessible antimicrobial agents. The in vitro activities of newer antibiotics, such as, ceftolozane/tazobactam (C/T) and ceftazidime/avibactam (CZA) along with some “older” antibiotics, for example fosfomycin (FOS) and colistin (CL) were determined against selected strains (resistant to $\ge 3$ antimicrobial agents) of Escherichia coli, Klebsiella pneumoniae, and Pseudomonas aeruginosa. Minimum inhibitory concentrations (MIC) were determined by Clinical and Laboratory Standards Institute microbroth dilution. 133 isolates: 46 E. coli, 39 K. pneumoniae, and 48 P. aeruginosa were tested. Results showed that E. coli isolates with MIC_50/90, 0.5/1 $\mathsf{\mu }\mathrm{g}/\mathrm{mL}$ for CL; 4/32 $\mathsf{\mu }\mathrm{g}/\mathrm{mL}$ for FOS; 0.25/32 $\mathsf{\mu }\mathrm{g}/\mathrm{mL}$ for C/T; 0.25/8 $\mathsf{\mu }\mathrm{g}/\mathrm{mL}$ for CZA, exhibited susceptibility rates of 95.7%, 97.8%, 76.1%, and 89.1%, respectively. On the other hand, K. pneumoniae strains with MIC_50/90, 0.5/1 $\mathsf{\mu }\mathrm{g}/\mathrm{mL}$ for CL; 256/512 $\mathsf{\mu }\mathrm{g}/\mathrm{mL}$ for FOS; 2/128 $\mathsf{\mu }\mathrm{g}/\mathrm{mL}$ for C/T; 0.5/128 $\mathsf{\mu }\mathrm{g}/\mathrm{mL}$ for CZA showed susceptibility rates of 92.3%, 7.7%, 51.3%, and 64.1%, respectively. P. aeruginosa isolates with MIC_50/90, 1/1 $\mathsf{\mu }\mathrm{g}/\mathrm{mL}$ for CL; 128/128 $\mathsf{\mu }\mathrm{g}/\mathrm{mL}$ for C/T; 32/64 $\mathsf{\mu }\mathrm{g}/\mathrm{mL}$ for CZA presented susceptibility rates of 97.9%, 33.3%, and 39.6%, respectively. Higher MICs were demonstrated against most of the antibiotics. However, CL retained efficacy at low MICs against most of the isolates tested. Full article

The fungus Pyrenophora tritici-repentis (Ptr) causes tan spot of wheat crops, which is an important disease worldwide. Based on the production of the three known necrotrophic effectors (NEs), the fungal isolates are classified into eight races with race 4 producing no known NEs. From a laboratory cross between 86–124 (race 2 carrying the ToxA gene for the production of Ptr ToxA) and DW5 (race 5 carrying the ToxB gene for the production of Ptr ToxB), we have obtained some Ptr isolates lacking both the ToxA and ToxB genes, which, by definition, should be classified as race 4. In this work, we characterized virulence of two of these isolates called B16 and B17 by inoculating them onto various common wheat (Triticum aestivum L.) and durum (T. turgidum L.) genotypes. It was found that the two isolates still caused disease on some genotypes of both common and durum wheat. Disease evaluations were also conducted in recombinant inbred line populations derived from two hard red winter wheat cultivars: Harry and Wesley. QTL mapping in this population revealed that three genomic regions were significantly associated with disease, which are different from the three known NE sensitivity loci. This result further indicates the existence of other NE-host sensitivity gene interactions in the wheat tan spot disease system. Full article

Takayasu arteritis (TAK) is a chronic vasculitis that mainly affects the aorta, its major branches, and the pulmonary arteries. Since the description of the first case by Mikito Takayasu in 1908, several aspects of this rare disease, including the epidemiology, diagnosis, and the appropriate clinical assessment, have been substantially defined. Nevertheless, while it is well-known that TAK is associated with a profound inflammatory process, possibly rooted to an autoimmune disorder, its precise etiology has remained largely unknown. Efforts to identify the antigen(s) that trigger autoimmunity in this disease have been unsuccessful, however, it is likely that viruses or bacteria, by a molecular mimicry mechanism, initiate or propagate the auto-immune process in this disease. In this article, we summarize recent advances in the understanding of TAK, with emphasis on new insights related to the pathogenesis of this entity that may contribute to the design of novel therapeutic approaches. Full article

An immunocompetent 82-year-old female was admitted to our hospital due to fever without clear origin and hyponatremia. In the following days, an acute and bilateral pulmonary infiltrate appeared with a progressive worsening in respiratory function. Chest x-ray and CT (Computed tomography) showed bilateral reticulonodular infiltrates. Bronchoscopic aspiration and bronchoalveolar lavage (BAL), and transbronchial lung biopsy (TBBX) studies did not reveal microbiological and histopathological diagnosis. Broad-spectrum antibiotics were non-effective, and the patient died due to respiratory failure. Necropsy study revealed a miliary tuberculosis affecting lungs, liver, bone marrow, spleen, kidney, arteries, pancreas, and adrenal glands. Some weeks after the patient´s death, mycobacterial cultures from sputum, BAL and TBBX samples were positive for Mycobacterium tuberculosis. Full article

In healthcare facilities, environmental surfaces may be a reservoir of infectious agents even though cleaning and disinfection practices play a role in the control of healthcare-associated infections. In this study, the effectiveness of cleaning/disinfection procedures has been evaluated in two hospital areas, which have different risk category classifications. According to the contract with the cleaning service, after the daily ambulatory activities, the housekeeping staff apply an alcohol-based detergent followed by a chlorine-based disinfectant (2% Antisapril, Angelini; 540 mg/L active chlorine), properly diluted and sprayed. The contract provides for the use of disposable microfiber wipes which must be replaced with new ones in each health out-patient department. Surface contamination was analyzed using cultural methods and ATP detection, performed with a high-sensitivity luminometer. The values 100 CFU/cm² and 40 RLU/cm² were considered as the threshold values for medium-risk category areas, while 250 CFU/cm² and 50 RLU/cm² were defined for the low-risk category ones. Air quality was evaluated using active and passive sampling microbiological methods and particle count (0.3 μm–10 μm) detection. The cleaning/disinfection procedure reduced the medium bacterial counts from 32 ± 56 CFU/cm² to 2 ± 3 CFU/cm² in the low-risk area and from 25 ± 40 CFU/cm² to 7 ± 11 CFU/cm² in the medium-risk one. Sample numbers exceeding the threshold values decreased from 3% and 13% to 1% and 5%, respectively. RLU values also showed a reduction in the samples above the thresholds from 76% to 13% in the low-risk area. From the air samples collected using the active method, we observed a reduction of 60% in wound care and 53% in an ambulatory care visit. From the air samples collected using the passive method, we highlighted a 71.4% and 50% reduction in microbial contamination in the medium-risk area and in the low-risk one, respectively. The 10 μm size particle counts decreased by 52.7% in wound care and by 63% in the ambulatory care visit. Correct surface sanitation proved crucial for the reduction of microbial contamination in healthcare settings, and plays an important role in ensuring air quality in hospital settings. Full article

Zika Virus (ZIKV) is primarily transmitted through mosquito bites. It can also be transmitted during sexual intercourse and in utero from mother to fetus. To gain preliminary insight into ZIKV pathology and immune responses on route of transmission, rhesus macaques (RMs) were inoculated with ZIKV (PRVABC59) via intravaginal (IVAG) (n = 3) or subcutaneous (sub Q) (n = 2) routes. Systemic ZIKV infection was observed in all RMs, regardless of the route of inoculation. After 9 days postinfection (dpi), ZIKV was not detected in the plasma of IVAG- and sub-Q-inoculated RMs. Importantly, RMs harbored ZIKV up to 60 dpi in various anatomical locations. Of note, ZIKV was also present in several regions of the brain, including the caudate nucleus, parietal lobe, cortex, and amygdala. These observations appear to indicate that ZIKV infection may be systemic and persistent regardless of route of inoculation. In addition, we observed changes in key immune cell populations in response to ZIKV infection. Importantly, IVAG ZIKV infection of RMs is associated with increased depletion of CD11C hi myeloid cells, reduced PD-1 expression in NK cells, and elevated frequencies of Ki67⁺ CD8⁺ central memory cells as compared to sub Q ZIKV-infected RMs. These results need to interpreted with caution due to the small number of animals utilized in this study. Future studies involving large groups of animals that have been inoculated through both routes of transmission are needed to confirm our findings. Full article

The Toxoplasma gondii cellular cycle has been widely studied in many lifecycle stages; however, the egress event still is poorly understood even though different types of molecules were shown to be involved. Assuming that there is no purpose or intentionality in biological phenomena, there is no such question as “Why does the parasite leaves the host cell”, but “Under what conditions and how?”. In this review we aimed to summarize current knowledge concerning T. gondii egress physiology (signalling pathways), structures, and route. Full article

Japanese encephalitis virus (JEV), a mosquito-borne zoonotic flavivirus, is an enveloped positive-strand RNA virus that can cause a spectrum of clinical manifestations, ranging from mild febrile illness to severe neuroinvasive disease. Today, several killed and live vaccines are available in different parts of the globe for use in humans to prevent JEV-induced diseases, yet no antivirals are available to treat JEV-associated diseases. Despite the progress made in vaccine research and development, JEV is still a major public health problem in southern, eastern, and southeastern Asia, as well as northern Oceania, with the potential to become an emerging global pathogen. In viral replication, the entry of JEV into the cell is the first step in a cascade of complex interactions between the virus and target cells that is required for the initiation, dissemination, and maintenance of infection. Because this step determines cell/tissue tropism and pathogenesis, it is a promising target for antiviral therapy. JEV entry is mediated by the viral glycoprotein E, which binds virions to the cell surface (attachment), delivers them to endosomes (endocytosis), and catalyzes the fusion between the viral and endosomal membranes (membrane fusion), followed by the release of the viral genome into the cytoplasm (uncoating). In this multistep process, a collection of host factors are involved. In this review, we summarize the current knowledge on the viral and cellular components involved in JEV entry into host cells, with an emphasis on the initial virus-host cell interactions on the cell surface. Full article

Zika virus (ZIKV) is primarily transmitted to humans by Aedes aegypti and Ae. albopictus. Vector–virus interactions influencing vector competence vary and depend on biological and environmental factors. A mosquito’s chronological age may impact its immune response against virus infection. Insecticides, source reduction, and/or public education are currently the best defense against mosquitoes that transmit ZIKV. This study assessed the effects of a mosquito’s chronological age at time of infection on its response to ZIKV infection. We exposed young (6–7 d post-emergence) and old (11–12 d post-emergence) Ae. albopictus to a sublethal dose of bifenthrin prior to oral exposure to blood meals containing ZIKV (7-day incubation period). Old mosquitoes experienced a significantly (p < 0.01) higher rate of mortality than young mosquitoes. Significantly higher ZIKV body titers (p < 0.01) were observed in the old control group compared to the young control group. Significantly higher (p < 0.01) ZIKV dissemination rates and leg titers (p < 0.01) were observed in old bifenthrin-exposed mosquitoes compared to old control mosquitoes or young bifenthrin-exposed or control mosquitoes. Hence, bifenthrin exposure may increase the potential for virus transmission; however, the degree of these impacts varies with mosquito age. Impacts of insecticides should be considered in risk assessments of potential vector populations. Full article

Zika virus (ZIKV) is a single-stranded RNA virus belonging to the arthropod-borne flaviviruses (arboviruses) which are mainly transmitted by blood-sucking mosquitoes of the genus Aedes. ZIKV infection has been known to be rather asymptomatic or presented as febrile self-limited disease; however, during the last decade the manifestation of ZIKV infection has been associated with a variety of neuroimmunological disorders including Guillain–Barré syndrome, microcephaly and other central nervous system abnormalities. More recently, there is accumulating evidence about sexual transmission of ZIKV, a trait that has never been observed in any other mosquito-borne flavivirus before. This article reviews the latest information regarding the latter and emerging role of ZIKV, focusing on the consequences of ZIKV infection on the male reproductive system and the epidemiology of human-to-human sexual transmission. Full article

The aim of this study was to evaluate the occurrence of parasitic infections in solid organ transplant (SOT) recipients. We conducted a systematic review of literature records on post-transplant parasitic infections, published from 1996 to 2016 and available on PubMed database, focusing only on parasitic infections acquired after SOT. The methods and findings of the present review have been presented based on the Preferred Reporting Items for Systematic Reviews and Meta-Analysis (PRISMA) checklist. From data published in the literature, the real burden of parasitic infections among SOT recipients cannot really be estimated. Nevertheless, publications on the matter are on the increase, probably due to more than one reason: (i) the increasing number of patients transplanted and then treated with immunosuppressive agents; (ii) the “population shift” resulting from immigration and travels to endemic areas, and (iii) the increased attention directed to diagnosis/notification/publication of cases. Considering parasitic infections as emerging and potentially serious in their evolution, additional strategies for the prevention, careful screening and follow-up, with a high level of awareness, identification, and pre-emptive therapy are needed in transplant recipients. Full article

Staphylococcus aureus (S. aureus) is a commensal bacteria on the human skin, which causes serious skin inflammation. Several immune cells, especially effector T cells (Teff), have been identified as key players in S. aureus-derived skin inflammation. However, the bacterial component that induces dramatic host immune responses on the skin has not been well characterized. Here, we report that S. aureus lipoprotein (SA-LP) was recognized by the host immune system as a strong antigen, so this response induced severe skin inflammation. SA-LP activated dendritic cells (DCs), and this activation led to Teff accumulation on the inflamed skin in the murine intradermal (ID) injection model. The skin-accumulated Teff pool was established by IFN-ɤ-producing CD4⁺ and CD8⁺T (Th1 and Tc1). SA-LP activated dermal DC (DDC) in a dominant manner, so that these DCs were presumed to possess the strong responsibility of SA-LP-specific Teff generation in the skin-draining lymph nodes (dLN). SA-LP activated DC transfer into the mice ear, which showed similar inflammation, accompanied with Th1 and Tc1 accumulation on the skin. Thus, we revealed that SA-LP has a strong potential ability to establish skin inflammation through the DC-Teff axis. This finding provides novel insights not only for therapy, but also for the prevention of S. aureus-derived skin inflammation. Full article

Cancer genome studies of Epstein-Barr virus (EBV)-associated tumors, including lymphoepithelioma-like carcinomas (LELC) of nasopharyngeal (NPC), gastric (EBVaGC) and lung tissues, and natural killer (NK)/T-cell lymphoma (NKTCL), reveal a unique feature of genomic alterations with fewer gene mutations detected than other common cancers. It is known now that epigenetic alterations play a critical role in the pathogenesis of EBV-associated tumors. As an oncogenic virus, EBV establishes its latent and lytic infections in B-lymphoid and epithelial cells, utilizing hijacked cellular epigenetic machinery. EBV-encoded oncoproteins modulate cellular epigenetic machinery to reprogram viral and host epigenomes, especially in the early stage of infection, using host epigenetic regulators. The genome-wide epigenetic alterations further inactivate a series of tumor suppressor genes (TSG) and disrupt key cellular signaling pathways, contributing to EBV-associated cancer initiation and progression. Profiling of genome-wide CpG methylation changes (CpG methylome) have revealed a unique epigenotype of global high-grade methylation of TSGs in EBV-associated tumors. Here, we have summarized recent advances of epigenetic alterations in EBV-associated tumors (LELCs and NKTCL), highlighting the importance of epigenetic etiology in EBV-associated tumorigenesis. Epigenetic study of these EBV-associated tumors will discover valuable biomarkers for their early detection and prognosis prediction, and also develop effective epigenetic therapeutics for these cancers. Full article

Poly (dl-lactide-co-glycolide) (PLGA) microspheres were synthesized as delivery system for the natural anti-parasitic compounds, Periglaucine A (PGA) and Betulinic acid (BA). Periglaucine A and Betulinic acid were encapsulated in PLGA nanoparticles by single emulsion method with an average particle size of approximately 100–500 nm. Periglaucine A and Betulinic acid encapsulation efficiency was observed to be 90% and 35% respectively. Anti-Acanthamoeba property of Periglaucine A and Betulinic acid remained intact after encapsulation. PGA-PLGA and BA-PLGA nanoparticles demonstrated inhibition in viability of Acanthamoeba triangularis trophozoites by 74.9%, 59.9%, 49.9% and 71.2%, 52.2%, 88% respectively at concentration of 100 µg/mL, 50 µg/mL and 25 µg/mL. Cytotoxicity of PGA-PLGA and BA-PLGA nanoparticles has been evaluated against lung epithelial cell line and showed dose dependent cytotoxicity value of IC₅₀ 2 µg/mL and 20 µg/mL respectively. Futher, increased viability was observed in lung epithelial cell line in higher doses of synthesized polymeric nanoparticles. Results indicate that poly (dl-lactide-co-glycolide) (PLGA) nanoparticles could be exploratory delivery systems for natural products to improve their therapeutic efficacy. Full article

An approach to manage seed-transmitted Fusarium crown-foot-root rot (FCR, Fusarium spp.) and common root rot (CRR, Bipolaris sorokiniana) on wheat, avoiding environmental risks of chemicals, is seed treatments with microbial metabolites. F. sambucinum strain FS-94 that induces resistance to tomato wilt was shown by this study to be a source of non-fungitoxic wheat-protecting metabolites, which were contained in a mycelium extract purified by gel-chromatography and ultrafiltration. Plant-protecting effect of the purified mycelial extract (PME) was demonstrated in vegetation experiments using a rolled-towel assay and by small-plot field trials. To elucidate mechanisms putatively underlying PME protective activity, tests with cultured Triticum aestivum and T. kiharae cells, particularly the extracellular alkalinization assay, as well as gene expression analysis in germinated wheat seeds were used. Pre-inoculation treatments of seeds with PME significantly decreased the incidence (from 30 to 40%) and severity (from 37 to 50%) of root rots on seedlings without any inhibition of the seed germination and potentiation of deoxynivalenol (DON), DON monoacetylated derivatives and zearalenon production in FCR agents. In vegetation experiments, reductions in the DON production were observed with doses of 0.5 and 1 mg/mL of PME. Pre-sowing PME application on seeds of two spring wheat cultivars naturally infected with FCR and CRR provided the mitigation of both diseases under field conditions during four growing seasons (2013–2016). PME-induced ion exchange response in cultured wheat cells, their increased survivability, and up-regulated expression of some defensins’ genes in PME-exposed seedlings allow the suggestion of the plant-mediated character of disease-controlling effect observed in field. Full article

Propionate is a common food preservative and one of the major fermentation acids in the intestines. Therefore, exposure to propionate is frequent for foodborne pathogens and likely takes place under suboxic conditions. However, it is not clear whether the absence of oxygen affects how pathogens respond to propionate. Here, we investigated how propionate exposure affects Listeria monocytogenes growth and virulence factor production under aerobic or anaerobic conditions and showed that oxygen indeed plays a key role in modulating L. monocytogenes response to propionate. Under aerobic conditions, propionate supplementations had no effect on planktonic growth but resulted in decreased adherent growth. Under anaerobic conditions, propionate supplementations resulted in a pH-dependent inhibition of planktonic growth and increased adherent growth. Cultures grown with propionate accumulated higher levels of acetoin under aerobic conditions but lower levels of ethanol under both aerobic and anaerobic conditions. Metabolic perturbations by propionate were also evident by the increase in straight chain fatty acids. Finally, propionate supplementations resulted in increased listeriolyin O (LLO) production under anaerobic conditions but decreased LLO production under aerobic conditions. These results demonstrate for the first time that the presence or absence of oxygen plays a critical role in shaping L. monocytogenes responses to propionate. Full article

Pathogenic viruses have evolved to manipulate the host cell utilising a variety of strategies including expression of viral proteins to hijack or mimic the activity of cellular functions. DNA tumour viruses often establish latent infection in which no new virions are produced, characterized by the expression of a restricted repertoire of so-called latent viral genes. These latent genes serve to remodel cellular functions to ensure survival of the virus within host cells, often for the lifetime of the infected individual. However, under certain circumstances, virus infection may contribute to transformation of the host cell; this event is not a usual outcome of infection. Here, we review how the Epstein–Barr virus (EBV), the prototypic oncogenic human virus, modulates host cell functions, with a focus on the role of the EBV latent genes in classical Hodgkin lymphoma. Full article

Fusarium head blight (FHB) is a highly detrimental disease of wheat. A quantitative trait locus for FHB resistance, Qfhb1, is the most utilized source of resistance in wheat-breeding programs, but very little is known about its resistance mechanism. In this study, we elucidated a prospective FHB resistance mechanism by investigating the proteomic signatures of Qfhb1 in a pair of contrasting wheat near-isogenic lines (NIL) after 24 h of inoculation of wheat florets by Fusarium graminearum. Statistical comparisons of the abundances of protein spots on the 2D-DIGE gels of contrasting NILs (fhb1+ NIL = Qfhb1 present; fhb1- NIL = Qfhb1 absent) enabled us to select 80 high-ranking differentially accumulated protein (DAP) spots. An additional evaluation confirmed that the DAP spots were specific to the spikelet from fhb1- NIL (50 spots), and fhb1+ NIL (seven spots). The proteomic data also suggest that the absence of Qfhb1 makes the fhb1- NIL vulnerable to Fusarium attack by constitutively impairing several mechanisms including sucrose homeostasis by enhancing starch synthesis from sucrose. In the absence of Qfhb1, Fusarium inoculations severely damaged photosynthetic machinery; altered the metabolism of carbohydrates, nitrogen and phenylpropanoids; disrupted the balance of proton gradients across relevant membranes; disturbed the homeostasis of many important signaling molecules induced the mobility of cellular repair; and reduced translational activities. These changes in the fhb1- NIL led to strong defense responses centered on the hypersensitive response (HSR), resulting in infected cells suicide and the consequent initiation of FHB development. Therefore, the results of this study suggest that Qfhb1 largely functions to either alleviate HSR or to manipulate the host cells to not respond to Fusarium infection. Full article

The mammalian gut is colonized by a large variety of microbes, collectively termed ‘the microbiome’. The gut microbiome undergoes rapid changes during the first few years of life and is highly variable in adulthood depending on various factors. With the gut being the largest organ of immune responses, the composition of the microbiome of the gut has been found to be correlated with qualitative and quantitative differences of mucosal and systemic immune responses. Animal models have been very useful to unravel the relationship between gut microbiome and immune responses and for the understanding of variations of immune responses to vaccination in different childhood populations. However, the molecular mechanisms underlying optimal immune responses to infection or vaccination are not fully understood. The gut virome and gut bacteria can interact, with bacteria facilitating viral infectivity by different mechanisms. Some gut bacteria, which have a beneficial effect on increasing immune responses or by overgrowing intestinal pathogens, are considered to act as probiotics and can be used for therapeutic purposes (as in the case of fecal microbiome transplantation). Full article