Antimicrobial Bacterial Metabolites: Properties, Applications and Loading in Liposomes for Site-specific Delivery.

The high levels of antibiotic resistance registered worldwide have become a serious health problem, threatening the currently available treatments for a series of infectious diseases. With antibiotics becoming less and less effective, it is becoming increasingly difficult and, in some cases, impossible to treat patients with even common infectious diseases, such as pneumonia. The inability to meet the ever-increasing demand to control microbial infection requires both the search for new antimicrobials and improved site-specific delivery. On the one hand, bacterial secondary metabolites are known for their diverse structure and antimicrobial potential and have been in use for a very long time in diverse sectors. A good deal of research is produced annually describing new molecules of bacterial origin with antimicrobial properties and varied applications. However, very few of these new molecules reach the clinical phase and even fewer are launched in the market for use. In this review article, we bring together information on these molecules with potential for application, in particular, for human and veterinary medicine, and the potential added value of the use of liposomes as delivery systems for site-specific delivery of these drugs with the synergistic effect to overcome the risk of antibiotic resistance.

Synthesis of chalcone derivatives by Claisen-Schmidt condensation and in vitro analyses of their antiprotozoal activities.

Chalcone is a molecule with known biological activities. Based on this, a series of chalcone derivatives bearing methyl, phenyl or furanyl substituents at different positions of A and B rings were synthesised, characterised, and evaluated regarding antiprotozoal activity. Molecules were synthesised via base catalyzed Claisen-Schmidt condensation and characterised by IR and NMR spectral data. Antiprotozoal activity against Phytomonas serpens, Leishmania amazonensis and Acanthamoeba polyphaga was performed. All compounds inhibited more than 50% of the growth of P. serpens while five had this effect on L. amazonensis and all of them no more than 35% of inhibition on A. polyphaga. Remarkably interesting antiprotozoal effects were recorded with compound 5, with IC50 of 1.59 µM for P. serpens and 11.49 µM for L. amazonensis. The addition of a naphthyl group to the B ring can be postulated to be the cause of the 10 times increase observed in its trypanocidal activity.

The role of IgA in gastrointestinal helminthiasis: A systematic review.

Immunoglobulin-A (IgA) is an important mediator of immunity and has been associated with protection against several pathogens, although its role in gastrointestinal infections remains unclear. Then, the aim of this systematic review was to synthesize qualitative evidence in respect of IgA as mediator of protective immunity against gastrointestinal helminths. Following recommended guidelines, we searched for articles published between January 1990 and October 2019 that evaluated IgA levels and their association with gastrointestinal helminth infections. Twenty-five articles were included after screening 1,546 titles and abstracts, as well as reading in full 52 selected articles. Consistent associations between higher IgA levels and lower parasitological parameters were only found in mice, rats, and sheep. However, the role of IgA in other host species remains uncertain, making it difficult to create a consensus. Therefore, it is too soon to claim that IgA is an effective protective factor against gastrointestinal helminths, and further studies are still needed.

Genomic features of mecA-positive methicillin-resistant Mammaliicoccus sciuri causing fatal infections in pets admitted to a veterinary intensive care unit.

Methicillin-resistant staphylococci have become leading cause of infectious diseases in humans and animals, being categorized as high priority pathogens by the World Health Organization. Although methicillin-resistant Staphylococcus sciuri (recently moved to Mammaliicoccus sciuri) has been widely reported in companion animals, there is scarce information regarding their clinical impact and genomic features. Herein, we reported the occurrence and genomic characteristics of methicillin-resistant M. sciuri recovered from fatal infections in pets admitted to an intensive care unit of a veterinary hospital, in Brazil. Two M. sciuri strains were isolated from bronchoalveolar lavage samples collected from dog (strain SS01) and cat (strain SS02) presenting with sepsis and acute respiratory distress syndrome. Both isolates displayed a multidrug-resistant profile, whereas whole-genome sequencing analysis confirmed the presence of the mecA gene, along to genetic determinant conferring resistance to macrolides, streptogramins, aminoglycosides, and trimethoprim. For both strains, the mec and crr gene complex shared high identity (≥97%) with analogue sequences from a M. sciuri isolated from a human wound infection, in the Czech Republic. Strains were assigned to the sequence type ST52 and the novel ST74. Phylogenomic analysis revealed a broad host range association of these strains with several hosts and sources, including humans, animals, food, and the environment through different years and geographic locations. Our findings demonstrate that infections caused by mecA-positive M. sciuri strains can be a serious threat for veterinary intensive care patients and the medical staff, with additional implications for One Health approaches.

Bacillus thuringiensis: From biopesticides to anticancer agents.

Bacillus thuringiensis (Bt) is a ubiquitous bacterium that produces several proteins that are toxic to different invertebrates such as insects, nematodes, mites, and also some protozoans. Among these, Cry and Cyt proteins are most explored as biopesticides for their action against agricultural pests and vectors of human diseases. In 2000, a group of researchers from Japan isolated parasporal inclusion proteins from B. thuringiensis, and reported their cytotoxic action against human leukemia. Later, other proteins with similar antitumor properties were also isolated from this bacterium and these cytotoxic proteins with specific activity against human cancer cells were named parasporins. At present, nineteen different parasporins are registered and classified in six families. These parasporins have been described to have specific in vitro antitumor activity against several cancer cell lines. The antitumor activity makes parasporins possible candidates as anticancer agents. Various research groups around the world are involved in isolating and characterizing in vitro antitumor activity of these proteins and many articles reporting such activities in detail have been published. However, there are virtually no data regarding the antitumor activity of parasporins in vivo. This review summarizes the properties of these potentially useful antitumor agents of natural origin, focusing on their in vivo activity thus also highlighting the importance of testing these proteins in animal models for a possible application in clinical oncology.

Bioactive compounds and hepatoprotective effect of Hancornia speciosa gomes fruit juice on acetaminophen-induced hepatotoxicity in vivo.

Hancornia speciosa Gomes (HS) is a Brazilian fruit tree used in inflammatory disorders by folk medicine. Here we sought to investigate the antioxidant and hepatoprotective properties of HS fruit juice in acetaminophen-induced hepatoxicity model in rats, as well as to perform a comprehensive chemical characterization of phenolics and metals by mass spectrometry. HS showed hepatoprotective and antioxidant activity by decreasing MDA and liver injury markers at healthy control levels. In addition, liver histopathological analysis revealed that HS decreases hepatocellular degeneration. Chemical characterization revealed 16 different phenolics, being chlorogenic acid (150 ± 5 µg/g) and rutin (120 ± 8 µg/g) the major phenolics in HS. Among the 14 micronutrients we identified, zinc and boron were the most abundant metals detected in HS. In line with previous studies involving liver diseases, our data supports evidence that such phenolics and metals present in HS may prevent liver injury induced by acetaminophen.

Epidemiological and diagnostic aspects of feline leishmaniasis with emphasis on Brazil: a narrative review.

The leishmaniases are a group of diseases caused by the protozoan parasite belonging to the genus Leishmania. In the New World, although dogs are considered the main parasite reservoir, in the last two decades, several studies have confirmed the role of cats (Felis catus) in the epidemiology of the disease and feline leishmaniasis (FeL) is now considered to be an emerging disease. The present review summarizes the current knowledge about FeL, focusing on important immunopathological aspects, epidemiology, and diagnostic methods applied for felines in Brazil. Cats are infected with the same species of Leishmania found in dogs (i.e., Leishmania infantum). Like dogs, skin lesions are the most common in cats with clinical FeL, mainly affecting the cephalic region and less frequently the legs which may be accompanied by generalized signs or visceral involvement. Information on the immune response of cats to Leishmania infection is scarce; however, efficient infection control is seen in most cases. For diagnosis, generally, the same methods as those in dogs are used, mainly serological tools. But there is a lack of studies focusing the performance of these methods for diagnosing FeL. The estimated overall prevalence of FeL in Brazil is 8%, with L. infantum being the most prevalent species. However, infections with Leishmania braziliensis and Leishmania amazonensis have also been reported. In conclusion, although there has been an increase in the publication related to FeL in Brazil in recent years, there is a lack of research relating immune response and diagnosis of these animals. Cats have been shown to be competent hosts for Leishmania parasites, and their role in the epidemiology of the disease cannot be underestimated, especially in areas of Brazil where the disease is historically endemic.

Intestinal polyparasitism and levels of mucosal anthelmintic SIgA in children from endemic areas in Northeastern Brazil.

Interactions between parasites during co-infections are often complex and can impact immunization and treatment programmes, as well as disease outcomes and morbidity. However, little is known about these interactions and the mechanisms involved. In this study, a coproparasitological survey was carried out in school-age children living in endemic areas of parasitic infection in the state of Sergipe, Northeastern Brazil. Anti-helminth-specific and total secretory immunoglobulin-A (SIgA) levels were measured in stool and saliva samples and were compared in children presenting monoparasitism, polyparasitism (helminths and/or intestinal protozoa) and no infections. The survey showed that protozoa were more prevalent than helminths, and that there was a high frequency of polyparasitism in the studied population, mainly from combinations of protozoan species. Although less frequent, combinations between species of protozoa and helminths were also observed. The levels of salivary SIgA in these co-infected individuals were lower than the average observed in infections with helminths alone. Although the children participating in this survey were asymptomatic, and it was, therefore, not possible to evaluate the impact of salivary SIgA reduction on the diseases, and the study highlights the need for further investigations of co-infections by intestinal parasites and the effects on immune response induced by the interactions between different parasites.

Anti-leishmanial compounds from microbial metabolites: a promising source.

Leishmania is a complex disease caused by the protozoan parasites and transmitted by female phlebotomine sandfly. The disease affects some of the poorest people on earth with an estimated 700,000 to 1 million new cases annually. The current treatment for leishmaniasis is toxic, long, and limited, in view of the high resistance rate presented by the parasite, necessitating new perspectives for treatment. The discovery of new compounds with different targets can be a hope to make the treatment more efficient. Microbial metabolites and their structural analogues with enormous scaffold diversity and structural complexity have historically played a key role in drug discovery. We found thirty-nine research articles published between 1999 and 2021 in the scientific database (PubMed, Science Direct) describing microbes and their metabolites with activity against leishmanial parasites which is the focus of this review. KEY POINTS: • Leishmania affects the poorest regions of the globe • Current treatments for leishmaniasis are toxic and of limited efficacy • Microbial metabolites are potential sources of antileishmania drugs.

Exploring Innovative Leishmaniasis Treatment: Drug Targets from Pre-Clinical to Clinical Findings.

Leishmaniasis is a group of tropical diseases caused by parasitic protozoa belonging to the genus Leishmania. The disease is categorized in cutaneous leishmaniasis (CL), mucocutaneous leishmaniasis (MCL), and visceral leishmaniasis (VL). The conventional treatment is complex and can present high toxicity and therapeutic failures. Thus, there is a continuing need to develop new treatments. In this review, we focus on the novel molecules described in the literature with potential leishmanicidal activity, categorizing them in pre-clinical (in vitro, in vivo), drug repurposing and clinical research.

Are Nanobiosensors an Improved Solution for Diagnosis of Leishmania?

Leishmaniasis is one of the deadliest neglected tropical diseases affecting 12-15 million people worldwide, especially in middle- and low-income countries. Rapid and accurate diagnosis of the disease is important for its adequate management and treatment. Several techniques are available for the diagnosis of leishmaniasis. Among these, parasitological and immunological tests are most widely used. However, in most cases, the utilized diagnostic techniques are not good enough, showing cross-reactivity and reduced accuracy. In recent years, many new methods have been reported with potential for improved diagnosis. This review focuses on the diagnosis of Leishmania exploring the biosensors and nanotechnology-based options for their detection. New developments including the use of nanomaterials as fluorophores, fluorescence quenchers as reducing agents and as dendrimers for signal improvement and amplification, together with the use of aptamers to replace antibodies are described. Future research opportunities to overcome the current limitations on the available diagnostic approaches are also discussed.

Changes in the epidemiological profile of intestinal parasites after a school-based large-scale treatment for soil-transmitted helminths in a community in northeastern Brazil: Epidemiological profile after large-scale school-based treatment for STH.

Intestinal parasites cause a significant public health problem worldwide due to the associated morbidities, mainly in infected school-aged children (SAC). The strategy of large-scale deworming in SAC to control the transmission of soil-transmitted helminths (STH) has been advocated by the World Health Organization and was recently adopted in Brazil; however, the long-term effects of mass deworming on the larger parasitological profile have been less studied. After a five-year period of school-based large-scale treatment for STH using an annual single dose of albendazole in a community of Sergipe state, Brazil, a marked reduction in prevalence was observed (15.4%% vs.7.4% for Ascaris sp., 6.0%%  vs. 0.4% for hookworm, and 12.8%%  vs. 4.5%% for Trichuris trichiura), with the exception of Strongyloides stercoralis, which had no statistically significant change in prevalence. There was, however, an increase in the prevalence of intestinal protozoans, specifically Entamoeba histolytica/E. dispar (0.0%% vs. 36.0%), Blastocystis hominis (0.0%%  vs. 40.1%), and Giardia duodenalis (5.6%% vs. 14.5%). Although the findings showed a dramatic reduction in the prevalence of STH after four rounds of preventive chemotherapy, there was an increase in intestinal protozoan infections, indicating a change in the epidemiological profile.

VanA-type vancomycin-resistant Enterococcus faecium ST1336 isolated from mussels in an anthropogenically impacted ecosystem.

We report the occurrence and genomic features of multidrug-resistant vancomycin-resistant Enterococcus faecium vanA belonging to a novel sequence type (designated ST1336), carrying a Tn1546-like element, in marine brown mussels (Perna perna) from anthropogenically affected coastal waters of the Atlantic coast of Brazil, highlighting a potential source of dissemination for related ecosystems, with additional consequences for seafood safety and quality.

Genomic analysis of MCR-1 and CTX-M-8 co-producing Escherichia coli ST58 isolated from a polluted mangrove ecosystem in Brazil.

OBJECTIVES: Genomic surveillance studies monitoring the dissemination of multidrug-resistant Enterobacteriaceae in polluted aquatic ecosystems are urgently required. The aim of this study was to report the draft genome sequence of an MCR-1 and CTX-M-8 co-producing Escherichia coli isolated from a polluted mangrove ecosystem in Northeast Brazil. METHODS: Total genomic DNA was sequenced on an Illumina NextSeq platform and was assembled using CLC Genomics Workbench. The whole-genome sequence was evaluated through bioinformatics tools available from the Center of Genomic Epidemiology as well as additional in silico analysis. RESULTS: The genome size was calculated at 5089467bp, comprising a total of 5068 protein-coding sequences. The strain was assigned to sequence type 58 (ST58) and revealed the presence of mcr-1, blaCTX-M-8 and other clinically significant genes responsible for conferring resistance to colistin, ß-lactams, trimethoprim and quinolones. In addition, genes conferring resistance to silver (silR) and quaternary ammonium compounds (sugE) were identified. CONCLUSION: These data provide valuable information for comparative genomic analysis regarding the dissemination of MCR-1-producing E. coli at the human-animal-environment interface.

Leishmanicidal Activity and Structure-Activity Relationships of Essential Oil Constituents.

Several constituents of essential oils have been shown to be active against pathogens such as bacteria, fungi, and protozoa. This study demonstrated the in vitro action of ten compounds present in essential oils against Leishmania amazonensis promastigotes. With the exception of p-cymene, all evaluated compounds presented leishmanicidal activity, exhibiting IC50 between 25.4 and 568.1 µg mL-1. Compounds with the best leishmanicidal activity presented a phenolic moiety (IC50 between 25.4 and 82.9 µg mL-1). Alicyclic alcohols ((-)-menthol and isoborneol) and ketones ((-)-carvone) promoted similar activity against the parasite (IC50 between 190.2 and 198.9 µg mL-1). Most of the compounds showed low cytotoxicity in L929 fibroblasts. Analysis of the structure-activity relationship of these compounds showed the importance of the phenolic structure for the biological action against the promastigote forms of the parasite.

Acute norovirus gastroenteritis in children in a highly rotavirus-vaccinated population in Northeast Brazil.

BACKGROUND: Gastroenteritis is one of the most important causes of morbidity and mortality in children and an important etiological agent is norovirus. OBJECTIVE: We describe the occurrence and characteristics of norovirus diarrhoea in children from Sergipe, Northeast-Brazil, over two consecutive periods of three years following rotavirus vaccine introduction. STUDY DESIGN: A cross sectional hospital-based survey conducted from October-2006 to September-2009 and from July-2011 to January-2013. Acute diarrhoea cases had a stool sample collected and tested for norovirus by RT-PCR and positive samples were sequenced. RESULTS: In total 280 (19.6%) of 1432 samples were norovirus positive, including 204 (18.3%) of 1113 samples collected during the first period and 76 (23.9%) of 318 collected during the second period. The proportion of children with norovirus infection increased significantly through the second study period (χ2 for trend=6.7; p=0.009), was more frequent in rotavirus vaccinated and in younger children (p<0.001). Of 280 norovirus-positive specimens, 188 (67.1%) were sequenced. Of these, 12 were genogroup I and 176 genogroup II. The main genotype was GII.4 (149/188, 79.3%), followed by GII.2 (6, 3.2%) and GII.6 (5, 2.6%). CONCLUSION: Norovirus annual detection rates increased over the study period. The detection of norovirus was higher among young children.

Incidence of rotavirus and circulating genotypes in Northeast Brazil during 7 years of national rotavirus vaccination.

BACKGROUND AND AIMS: Rotavirus causes severe diarrhoea and Brazil introduced the Rotarix G1P[8] vaccine in 2006. We aimed to describe changes in rotavirus incidence and diarrhoea epidemiology before and after vaccine introduction. DESIGN: (i) hospital-based survey of children with diarrhoea (2006-2012); (ii) diarrhea-mortality and hospitalization surveillance (1999-2012). SETTING: (i) Aracaju and (ii) state and national level. RESULTS: 1841 children were enrolled and 231 (12.5%) had rotavirus. Rotavirus was less frequent from January-June than from July-December (9.4% versus 20.9%, p<0.01), but the seasonal variation was less defined after 2009. Very few rotavirus cases (8-3.9%) were detected in 2011, with an increase in 2012 (13-18.5%). In 2006, unvaccinated children were more likely to have rotavirus, but thereafter unvaccinated and vaccinated children had equally low incidence. Older children and those with rotavirus were more likely to have severe diarrhea episodes. The most frequent genotype from 2006 to 2010 was G2P[4]; except in 2009, when most cases were G1P[8]. Very few G2P[4] were detected from 2011 and 50% cases in 2012 were G8P[4]. Diarrhoea-hospitalizations decreased nationally from 89,934 (2003) to 53,705 (2012; 40.3% reduction) and in the state from 1729 to 748 (56.7% reduction). Diarrhoea-deaths decreased nationally from 4368 in 1999 to 697 in 2012 (84% reduction, p<0.001) and in the state from 132 to 18 (86% reduction). These changes were much larger after vaccine introduction. CONCLUSIONS: The vaccine was associated with substantial reductions in rotavirus incidence and diarrhoea-hospitalizations and deaths. The G2P[4] genotype predominance disappeared over time and may be replaced by other heterotypic genotypes.

Underreporting of Dengue-4 in Brazil due to low sensitivity of the NS1 Ag test in routine control programs.

We have identified fifty-eight samples that were positive for Dengue-4 among 119 samples with negative diagnoses for dengue via the Platelia™ dengue NS1 Ag in Aracaju, State of Sergipe, Brazil. We determined that the low sensitivity of the NS1 Ag test could be related to secondary dengue infections in the studied population. Therefore, we concluded that the sensitivity and specificity of the Platelia™ dengue NS1 Ag test as a screening method for monitoring circulating dengue serotypes must be reevaluated. In addition, regional endo-epidemic profiles should also be considered due to the prevalence of secondary responses.

Amoebic liver abscess production by Entamoeba dispar.

Although Entamoeba dispar displays a similar morphology to Entamoeba histolytica, cellular and molecular studies have revealed significant differences between these two amoebae, including the former being characterized as non-pathogenic and the later as pathogenic. However, recent in vivo and in vitro experiments have shown that E. dispar strains of different origin are capable of causing liver damage and destroying cell culture lines in the presence of common intestinal bacteria. These results suggested that E. dispar may present pathogenic behavior according to the specific E. dispar strain, culture and environmental conditions. To investigate this possibility, we carried out in vivo and in vitro studies using a xenic strain E. dispar (ICB-ADO) isolated from a symptomatic non-dysenteric Brazilian patient. This strain was able to induce liver necrosis in a hamster model that was more severe than that produced by E. histolytica. The ICB-ADO isolate also caused significantly more destruction of cultured MDCK cells and increased loss of transepithelial resistance than did the E. histolytica. Xenic E. dispar exhibited high proteolytic activity, which was partially inhibited by the addition of cysteine-protease inhibitors. Based on our biochemical and molecular characterization of E. dispar (ICB-ADO) xenic culture and its ability to produce liver abscesses, we conclude that this specific strain can indeed produce tissue damage, distinct from the frequently used non- pathogenic E. dispar SAW 760 strain.

Prevalence of intestinal parasites in children from public daycare centers in the city of Belo Horizonte, Minas Gerais, Brazil.

The objective of this study was to verify the occurrence of intestinal parasites in 3 to 6-year-old children from daycare centers maintained by the municipal government of Belo Horizonte, Minas Gerais, Brazil. Coproparasitological tests performed in 472 children have shown that 24.6% of them had some type of parasites, 6.6% of the children having more than one type. Among protozoa, Entamoeba coli (14.0%) and G. duodenalis (9.5%) were the most prevalent, whereas Ascaris lumbricoides (3.0%) and Trichuris trichiura (1.1%) were the most frequent among the helminths. Thus, we can observe that intestinal parasites still represent a serious public health problem in Belo Horizonte, especially among children and in areas where the socioeconomic conditions are less favorable.