Plasmodium sporozoites trickle out of the injection site

Plasmodium sporozoites make a remarkable journey from the skin, where they are deposited by an infected Anopheline mosquito, to the liver, where they invade hepatocytes and develop into exoerythrocytic stages. Although much work has been done to elucidate the molecular mechanisms by which sporozoites invade hepatocytes, little is known about the interactions between host and parasite before the sporozoite enters the blood circulation. It has always been assumed that sporozoites rapidly exit the injection site, making their interactions with the host at this site, brief and difficult to study. Using quantitative PCR, we determined the kinetics with which sporozoites leave the injection site and arrive in the liver and found that the majority of infective sporozoites remain in the skin for hours. We then performed sub-inoculation experiments which confirmed these findings and showed that the pattern of sporozoite exit from the injection site resembles a slow trickle. Last, we found that drainage of approximately 20% of the sporozoite inoculum to the lymphatics is associated with a significant enlargement of the draining lymph node, a response not observed after intravenous inoculation. These findings indicate that there is ample time for host and parasite to interact at the inoculation site and are of relevance to the pre-erythrocytic stage malaria vaccine effort.

Cloning, characterization, and epitope expression of the major diagnostic antigen of Paracoccidioides brasiliensis

The 43,000-Da glycoprotein (gp43) of Paracoccidioides brasiliensis is an immunodominant antigen for antibody-dependent and immune cellular responses in patients with paracoccidioidomycosis. In order to identify the peptide epitopes involved in the immunological reactivities of the gp43 and to obtain highly specific recombinant molecules for diagnosis of the infection, genomic and cDNA clones representing the entire coding region of the antigen were sequenced. The gp43 open reading frame was found in a 1,329-base pair fragment with 2 exons interrupted by an intron of 78 nucleotides. The gene is present in very few copies per genome, as indicated by Southern blotting and chromosomal megarestriction analysis. A single transcript of 1.5 kilobase pairs was verified in the yeast phase. The gene encodes a polypeptide of 416 amino acids (Mr 45,947) with a leader peptide of 35 residues; the mature protein has a single N-glycosylation site. The deduced amino acid sequence showed similarities of 56-58% with exo-1,3- beta-D-glucanases from Saccharomyces cerevisiae and Candida albicans. However, the gp43 is devoid of hydrolase activity and does not cross-react immunologically with the fungal glucanases. Internal and COOH-terminal gene fragments of the gp43 were expressed as recombinant fusion proteins, which reacted with antibodies elicited against the native antigen.

Evaluation of recombinant antigens for serodiagnosis of Chagas' disease in South and Central America

The commercially available diagnostic tests for Chagas' disease employ whole extracts or semipurified fractions of Trypanosoma cruzi epimastigotes. Considerable variation in the reproducibility and reliability of these tests has been reported by different research laboratories, mainly due to cross-reactivity with other pathogens and standardization of the reagents. The use of recombinant antigens for the serodiagnosis of Chagas' disease is recommended to increase the sensitivity and specificity of serological tests. Expressed in Escherichia coli, as fusion products with glutathione S-transferase, six T. cruzi recombinant antigens (H49, JL7, A13, B13, JL8, and 1F8) were evaluated in an enzyme-linked immunosorbent assay for Chagas' disease. The study was carried out with a panel of 541 serum samples of chagasic and nonchagasic patients from nine countries of Latin America (Argentina, Bolivia, Brazil, Chile, Colombia, El Salvador, Guatemala, Honduras, and Venezuela). The optimal concentration of each recombinant antigen for coating of plates was determined with the help of 125I-labelled recombinant proteins. While the specificity of the epimastigote antigen was 84% because of false positives from leishmaniasis cases, for the recombinant antigens it varied from 96.2 to 99.6%. Recombinant antigens reacted with 79 to 100% of serum samples from chronic chagasic patients. In this way, it is proposed that a mixture of a few T. cruzi recombinant antigens should be employed in a diagnostic kit to minimize individual variation and promote high sensitivity in the diagnosis of Chagas' disease.

Combination of fluconazole with silver nanoparticles produced by Fusarium oxysporum improves antifungal effect against planktonic cells and biofilm of drug-resistant Candida albicans

Silver nanoparticles (AgNPs) have been extensively studied because of their anti-microbial potential. Here, we evaluated the effect of biologically synthesized silver nanoparticles (AgNPbio) alone and in combination with fluconazole (FLC) against planktonic cells and biofilms of FLC-resistant Candida albicans AgNPbio exhibited a fungicidal effect, with a minimal inhibitory concentration (MIC) and fungicidal concentration ranging from 2.17 to 4.35 μg/ml. The combination of AgNPbio and FLC reduced the MIC of FLC around 16 to 64 times against planktonic cells of allC. albicans There was no significant inhibitory effect of AgNPbio on biofilm cells. However, FLC combined with AgNPbio caused a significant dose-dependent decrease in the viability of both initial and mature biofilm. All concentrations of AgNPbio, alone or in combination with FLC, were not cytotoxic to mammalian cells.The results highlight the effectiveness of the combination of AgNPbio with FLC against FLC-resistant C. albicans.

CCR2 receptor is essential to activate microbicidal mechanisms to control Toxoplasma gondii infection in the central nervous system

Chemokines comprise a structurally related family of cytokines that regulate leukocyte trafficking. Because infection with Toxoplasma gondii can induce an important inflammatory reaction that, if left uncontrolled, can lead to death, we investigated the role of the chemokine receptor CCR2 in T. gondii infection. We orally infected CCR2(-/-) mice with five ME-49 T. gondii cysts and monitored morbidity, survival, and immune response thereafter. The CCR2(-/-) mice displayed higher susceptibility to infection as all mice died on day 28 after infection. Despite similar Th1 responses, a more evident anti-inflammatory response was induced in the peripheral organs of CCR2(-/-) mice compared with wild-type C57BL/6 mice. Additionally, CCR2(-/-) mice presented greater parasitism and a milder inflammatory reaction in their peripheral organs with lesser CD4(+) and MAC-1(+) and greater CD8(+) cell migration. The parasite load decreased in these organs in CCR2(-/-) mice but remained uncontrolled in the central nervous system. Additionally, we observed down-regulated inducible nitric oxide synthase expression in peripheral organs from CCR2(-/-) mice that was associated with a small nitric oxide production by spleen macrophages. In conclusion, in the absence of CCR2, another mechanism is activated to control tissue parasitism in peripheral organs. Nevertheless, CCR2 is essential for the activation of microbicidal mediators that control T. gondii replication in the central nervous system.

Commensal Streptococcus agalactiae isolated from patients seen at University Hospital of Londrina, Paraná, Brazil: capsular types, genotyping, antimicrobial susceptibility and virulence determinants

BACKGROUND

Streptococcus agalactiae or Group B Streptococci (GBS) have the ability to access various host sites, which reflects its adaptability to different environments during the course of infection. This adaptation is due to the expression of virulence factors that are involved with survival, invasion and bacterial persistence in the host. This study aimed to characterize GBS isolates from women of reproductive age seen at University Hospital of Londrina, according to capsular typing, genetic relatedness, antimicrobial susceptibility profile and occurrence of virulence determinants.

RESULTS

A total of 83 GBS isolates were enrolled in this study. Capsular types Ia (42.2%), II (10.8%), III (14.5%) and V (30.1%) were identified in most GBS. One isolate each was classified as type IX and non-typeable.A total of 15 multiple locus variable number of tandem repeat analysis (MLVA) types were identified among the isolates, seven were singletons and eight were represented by more than four isolates. All isolates were susceptible to penicillin, ampicillin, cefepime, cefotaxime, chloramphenicol, levofloxacin and vancomycin. Resistance to erythromycin and clindamycin was observed in 19.3 and 13.3% of isolates, respectively. All isolates resistant to clindamycin were simultaneously resistant to erythromycin and were distributed in the capsular types III and V. One isolate showed the constitutive macrolide-lincosamide-streptogramin B (cMLS(B)) phenotype and ten showed the inducible MLS(B) (iMLS(B)) phenotype. The mechanism of resistance to erythromycin and clindamycin more prevalent among these isolates was mediated by the gene ermA, alone or in combination with the gene ermB. The isolates displaying resistance only to erythromycin belonged to capsular type Ia, and showed the M phenotype, which was mediated by the mefA/E gene. All isolates harbored the gene hylB and at least one pilus variant, PI-1, PI-2a or PI-2b. Although cylE was observed in all GBS, four isolates were classified as gamma-hemolytic and carotenoid pigment non-producers.

CONCLUSIONS

Our results indicate the potential virulence of commensal GBS isolates, reinforcing the need for continued screening for this bacterium to prevent infections. The distribution of capsular and pili antigens, and MLVA profiles was also identified, which may contribute to the development of new strategies for the prevention and treatment of GBS infection.

In vitro and in vivo trypanocidal synergistic activity of N-butyl-1-(4-dimethylamino)phenyl-1,2,3,4-tetrahydro-β-carboline-3-carboxamide associated with benznidazole

American trypanosomiasis, or Chagas' disease, is caused by Trypanosoma cruzi and affects around 15 million people throughout the American continent. The available treatment is based on two nitroheterocyclic drugs, nifurtimox and benznidazole, both only partially effective and toxic. In this context, new drugs must be found. In our previous work, the tetrahydro-β-carboline compound N-butyl-1-(4-dimethylamino)phenyl-1,2,3,4-tetrahydro-β-carboline-3-carboxamide, named C4, showed a potent in vitro trypanocidal effect. The goal of this study was to evaluate the in vitro and in vivo trypanocidal effects of the compound C4 associated with other drugs (benznidazole, ketoconazole, and amphotericin B). For this, we used the checkerboard technique to analyze the effect of combinations of C4 reference drugs. C4 was assayed in a murine model alone as well as in association with benznidazole. We also evaluated the parasitemia, mortality, weight, and presence of amastigote nests in cardiac tissue. A synergic effect of C4 plus benznidazole against epimastigote and trypomastigote forms was observed in vitro, and in the murine model, we observed a substantial reduction in parasitemia levels and lowered mortality rates. These findings encourage supplementary investigations of carboline compounds as potential new trypanocidal drugs.

Characterization of a cDNA clone encoding the carboxy-terminal domain of a 90-kilodalton surface antigen of Trypanosoma cruzi metacyclic trypomastigotes

We have cloned and sequenced a cDNA for a metacyclic trypomastigote-specific glycoprotein with a molecular mass of 90 kDa, termed MTS-gp90. By immunoblotting, antibodies to the MTS-gp90 recombinant protein reacted exclusively with a 90-kDa antigen of metacyclic trypomastigotes. The insert of the MTS-gp90 cDNA clone strongly hybridized with a single 3.0-kb mRNA of metacyclic forms, whereas the hybridization signal with epimastigote mRNA was weak and those with RNAs from other developmental stages were negative, indicating that transcription of the MTS-gp90 gene is developmentally regulated. A series of experiments showed that the MTS-gp90 gene is present in multiple copies in the Trypanosoma cruzi genome, arranged in a nontandem manner, and that there are at least 40 copies of the gene per haploid genome. Sequence analysis of recombinant MTS-gp90 revealed 40 to 60% identity at the amino acid level with members of a family of mammalian stage-specific, 85-kDa surface antigens of T. cruzi. However, there are considerable differences in the amino acid compositions outside the homology region.

A recombinant protein based on the Trypanosoma cruzi metacyclic trypomastigote 82-kilodalton antigen that induces and effective immune response to acute infection

To further investigate the immunological properties of the stage-specific 82-kDa glycoprotein (gp82) of Trypanosoma cruzi metacyclic trypomastigotes, previously shown to induce antigen-specific humoral and T-cell responses in mice, we performed a series of experiments with recombinant proteins containing sequences of gp82 fused to glutathione S-transferase. Of five fusion proteins tested, only J18b and J18b1, the carboxyproximal peptides containing amino acids 224 to 516 and 303 to 516, respectively, were recognized by monoclonal antibody 3F6 as well as by various anti-T. cruzi antisera and, when administered to mice, were capable of eliciting antibodies directed to the native gp82. The amino-terminal peptide and other carboxyterminal recombinant proteins lacking the central domain of gp82 (amino acids 224 to 356), which is exposed on the surface of live metacyclic forms, did not display any of these properties. Spleen cells derived from mice immunized with any of the five recombinant proteins proliferated in vitro in the presence of native gp82.J18b was the most stimulatory, whereas J18b3, the peptide containing amino acids 408 to 516, elicited the weakest response. When BALB/c mice immunized with J18b antigen plus A1(OH)3 as adjuvant were challenged 10 5 metacyclic trypomastigotes, 85% of them resisted acute infection, in comparison with control mice that received glutathione S-transferase plus adjuvant. Antibodies induced by J18b protein lacked agglutinating or complement-dependent lytic activity and failed to neutralize parasite infectivity. On the other hand, CD4+T cells from the spleens of J18b-immunized mice displayed an intense proliferative activity upon stimulation with 1.25 microgram of native gp82 per ml, which resulted in increased production of gamma interferon, a cytokine associated with resistance to T. cruzi infection.

Candida species isolated from urban bats of Londrina-Paraná, Brazil and their potential virulence

The aim of this study was to isolate yeasts from the faeces of urban bats inhabiting the city of Londrina, Paraná, Brazil and to determine their potential virulence attributes. Seven (12.3%) of 57 bats screened in this study showed yeasts in their faeces. Five species of the genus Candida were isolated: C. guilliermondii, C. krusei, C. lusitaniae, C. parapsilosis, and C. pelliculosa. No phospholipase activity was detected in the egg yolk plate assay; however, all isolates demonstrated protease secretion in skim milk agar. Yeasts isolated from bats produced biofilm on the surface of polystyrene plates and all were classified as intermediate biofilm producers. Minimal inhibitory concentration (MIC) values for fluconazole in the yeasts varied according to the species. Only one isolate (M34 - C. lusitaniae) was considered susceptible dose-dependent to fluconazole. The yeasts were injected intravenously into Swiss mice, and at 15 days post-infection, the animals were killed and portions of their kidneys cultured on Sabouraud dextrose agar medium. All tissues analysed showed positive cultures of Candida spp. This is the first study evaluating the presence of fungi in the faeces of bats in an urban region, where the yeast species found were shown to be potentially pathogenic. As bats are commonly found in cities, these findings indicate the need for continuous surveillance concerning environmental contamination by their excreta.

Trypanocidal activity of copaiba oil and kaurenoic acid does not depend on macrophage killing machinery

Activity, mechanisms of action, and toxicity of natural compounds have been investigated in a context in which knowledge on which pathway is activated remains crucial to understand the action mechanism of these bioactive substances when treating an infected host. Herein, we showed an ability of copaiba oil and kaurenoic acid to eliminate Trypanosoma cruzi forms by infected macrophages through other mechanisms in addition to nitric oxide, reactive oxygen species, iron metabolism, and antioxidant defense. Both compounds induced an anti-inflammatory response with an increase in IL-10 and TGF-β as well as a decrease in IL-12 production. Despite being able to modulate the immune response in host cells, the antimicrobial activity of copaiba oil and kaurenoic acid seems to be a direct action of the compounds on the parasites, causing their death.

Oral Candida colonization in HIV-infected patients in Londrina-PR, Brazil: antifungal susceptibility and virulence factors

INTRODUCTION

Host colonization by Candida species is an important predisposing factor to candidiasis, which seems to be more frequent in human immunodeficiency virus (HIV)-infected patients. Knowledge about the distribution, antifungal susceptibility, and virulence of oral Candida isolates is important for effective management of candidiasis.

METHODOLOGY

Oral rinses were collected from 242 HIV-infected patients without clinical evidence of candidiasis seen at the AIDS referral center in Londrina, Brazil. Species were identified by standard phenotypic and molecular methods, and characterized in vitro according to antifungal susceptibility, cell surface hydrophobicity, biofilm formation, and enzyme activities.

RESULTS

Oral Candida colonization was detected in 50.4% of patients and combined use of antiretroviral therapy and protease inhibitor had a protective effect against colonization. Candida albicans (75.2%) was the most prevalent species. A high proportion of Candida spp. (39.9%) showed decreased susceptibility to fluconazole. Five isolates were resistant to nystatin. Protease and phospholipase activities were detected in 100% and 36.8% of isolates, respectively. Most isolates displayed a hydrophobic property that was associated with biofilm formation ability.

CONCLUSIONS

A significant number of oral Candida species exhibiting decreased susceptibility to fluconazole were isolated from colonized HIV-infected individuals. Furthermore, all isolates expressed potential virulence attributes in vitro. Given the high incidence and severity of fungal infections in HIV-infected individuals, the results of this study reinforce the importance of antifungal susceptibility testing, which contributes to therapeutic strategies and highlights the need for continuous surveillance of Candida colonization in this population.

Multidrug- and Extensively Drug-Resistant Acinetobacter baumannii in a Tertiary Hospital from Brazil: The Importance of Carbapenemase Encoding Genes and Epidemic Clonal Complexes in a 10-Year Study

This study aimed to characterize the main mechanisms of acquired antimicrobial resistance of 103 multidrug-resistant Acinetobacter baumannii isolated from bloodstream from 2006 to 2016 from a hospital in Londrina, Brazil. All 103 isolates were identified as A. baumannii by amplification of the bla_OXA-51-like and rpoB genes. Mortality was observed in the majority (81.6%) of the patients. High non-susceptibility rates (100.0-10.7%) were obtained for the evaluated antimicrobials, including colistin, polymyxin B, and tigecycline, and most isolates were classified as extensively drug-resistant (78.6%). Carbapenemase production was observed in 92.2% of the isolates. All carbapenem-resistant isolates showed a carbapenem-hydrolyzing class D β-lactamase being either bla_OXA-23-like (97.9%) or bla_OXA-143-like (2.1%). None of the isolates had the genes bla_OXA-24-like, bla_OXA-58-like, bla_OXA-48, bla_KPC, bla_NDM, bla_SPM-1, bla_SIM-1, bla_VIM, bla_IMP, bla_GIM, bla_GES, mcr-1, qnrA, qnrB, qnrC, qnrS, and qnrVc. As a genetic context of the bla_OXA-23-like gene, Tn2006 was predominated (86.0%), and Tn2008 was less frequent (12.9%). Isolates harboring the bla_OXA-143-like gene showed the bla_OXA-253-like variant. A polyclonal profile was observed among the A. baumannii isolates. The presence of the international clonal complexes CC113/79, CC109/1, CC110/25, and CC103/15 was detected, with prevalence of CC113/79 (38.8%). This study provides essential information to understand the antimicrobial resistance patterns of A. baumannii and can be used to strengthen infection control measures in our hospital. Also, the study reinforces the urgent need to develop stewardship programs to avoid the spread and potential outbreaks by this pathogen.

Selective Antiprotozoal Activity of Nitric Oxide-releasing Chitosan Nanoparticles Against Trypanosoma cruzi: Toxicity and Mechanisms of Action

BACKGROUND

Chagas' disease, caused by Trypanosoma cruzi, was described for the first time over a hundred years ago. Nonetheless, clinically available drugs still lack effective and selective properties. Nitric oxide (NO) produced by activated macrophages controls the progression of disease by killing the parasite.

METHODS AND RESULTS

Here, chitosan nanoparticles (CS NPs) were synthesized and mercaptosuccinic acid (MSA), the NO donor precursor, was encapsulated into CS NPs, forming MSA-CS NPs, which had hydrodynamic size of 101.0±2.535 nm. Encapsulated MSA was nitrosated forming NO donor S-nitrosomercaptosuccinic acid-containing nanoparticles (S-nitroso-MSA-CS NPs). Kinetic data revealed a sustained release of NO from the nanoparticles. S-nitroso-MSA-CS NPs inhibited epimastigote proliferation and trypomastigote viability of T. cruzi, with IC50=75.0±6.5 µg·mL-1 and EC50=25.0±5.0 µg·mL-1, respectively. Treatment of peritoneal macrophages with nanoparticles decreased the number of T. cruzi-infected cells and the average number of intracellular replicative amastigotes per infected cells. Besides, the results have showed a selective behaviour of S-nitroso-MSA-CS NPs to parasites. Morphological and biochemical changes induced by these NO-releasing nanoparticles, such as cell shrinkage, cell cycle arrest, mitochondrial membrane depolarization and phosphatidylserine exposure on cell surface indicate that epimastigotes death is associated to the apoptotic pathway.

CONCLUSION

S-nitroso-MSA-CS NPs are promising nanocarriers for the treatment of Chagas's disease.

Fatal sepsis caused by mecA-positive oxacillin-susceptible Staphylococcus aureus: First report in a tertiary hospital of southern Brazil

mecA-positive oxacillin phenotypically susceptible Staphylococcus aureus (OS-MRSA) is increasingly reported worldwide. This bacterium poses a therapeutic threat, as it can be misidentified as an oxacillin-susceptible organism by phenotypic methods that are routinely used in the majority of clinical microbiology laboratories. Herein, we report the first case of fatal sepsis in a 43-year-old female patient caused by an OS-MRSA SCCmec type IVa/ST1/CC1 in a tertiary hospital in southern Brazil, which highlights the difficulties involved in diagnosing this bacterium. Blood cultures and phenotypic susceptibility tests on admission yielded a penicillin-resistant S. aureus. Although vancomycin therapy was initiated, this antibacterial was replaced by oxacillin, based on the susceptibility result. However, the clinical conditions of the patient deteriorated rapidly evolving to fatal septic shock. Clinical microbiology laboratories should consider the use of additional tests to accurately distinguish between various antimicrobial phenotypes of S. aureus.

Isolation and characterisation of genomic and cDNA clones coding for a serine-, alanine-, and proline-rich protein of Trypanosoma cruzi

We report here the isolation and characterisation of genomic and cDNA clones encoding a Serine-, Alanine-, and Proline-rich protein (SAP) of Trypanosoma cruzi metacyclic trypomastigotes. The deduced peptides translated from these clones were characterised by a high content of residues of alanine, proline, serine, glycine, valine, and threonine distributed in several repeats: P(2-4), S(2-3), A(2-3), AS, SA, PA, AP, SP, PS, and TP. The repeats are partially homologous to the serine-, alanine-, and proline-containing motifs of Leishmania major and Leishmania mexicana proteophosphoglycans. Genes coding for SAP are part of a polymorphic family whose members are linked to members of gp85/sialidase and mucin-like gene families. This is consistent with the hypothesis that this genetic organisation could be a means by which T. cruzi co-ordinates the expression of major surface proteins.

Molecular and phenotypic characteristics of methicillin-resistant Staphylococcus aureus isolated from hospitalized patients

INTRODUCTION

Methicillin-resistant Staphylococcus aureus (MRSA) is one of the leading causes of infections acquired in both community and hospital settings. In this study, MRSA isolated from different sources of hospitalized patients was characterized by molecular and phenotypic methods.

METHODOLOGY

A total of 123 S. aureus isolates were characterized according to their genetic relatedness by repetitive element sequence based-PCR (REP-PCR), in vitro antimicrobial susceptibility profile, SCCmec typing and presence of seven virulence factor-encoding genes.

RESULTS

REP-PCR fingerprinting showed low relatedness between the isolates, and the predominance of one specific lineage or clonal group was not observed. All isolates were susceptible to teicoplanin and linezolide. All isolates were resistant to cefoxitin and penicillin, and the majority were also resistant to one or more other antimicrobials. Fifty isolates (41.7%) were intermediately resistant to vancomycin. Most isolates harbored SCCmec type II (53.7%), followed by type I (22.8%), type IV (8.1%) and type III (1.6%). All isolates harbored at least two virulence factor-encoding genes, and the prevalence was as follows: coa, 100%; icaA, 100%; hla, 13.0%; hlb, 91.1%, hld, 91.1%; lukS-PV and lukF-PV, 2.4%; and tst, 34.1%. A positive association with the presence of hla and SCCmec type II, and tst and SCCmec type I was observed.

CONCLUSION

This study showed the high virulence potential of multidrug-resistant MRSA circulating in a teaching hospital. A high prevalence of MRSA showing intermediate vancomycin resistance was also observed, indicating the urgent need to improve strategies for controlling the use of antimicrobials for appropriate management of S. aureus infections.

Trypanosoma cruzi: Inhibition of infection of human monocytes by aspirin

Cell invasion by Trypanosoma cruzi and its intracellular replication are essential for progression of the parasite life cycle and development of Chagas disease. Prostaglandin E2 (PGE₂) and other eicosanoids potently modulate host response and contribute to Chagas disease progression. In this study, we evaluated the effect of aspirin (ASA), a non-selective cyclooxygenase (COX) inhibitor on the T. cruzi invasion and its influence on nitric oxide and cytokine production in human monocytes. The pretreatment of monocytes with ASA or SQ 22536 (adenylate-cyclase inhibitor) induced a marked inhibition of T. cruzi infection. On the other hand, the treatment of monocytes with SQ 22536 after ASA restored the invasiveness of T. cruzi. This reestablishment was associated with a decrease in nitric oxide and PGE₂ production, and also an increase of interleukin-10 and interleukin-12 by cells pre-treated with ASA. Altogether, these results reinforce the idea that the cyclooxygenase pathway plays a fundamental role in the process of parasite invasion in an in vitro model of T. cruzi infection.

Aspirin treatment exacerbates oral infections by Trypanosoma cruzi

Oral transmission of the protozoan parasite Trypanosoma cruzi, the etiological agent of Chagas disease, has been documented in Latin American countries. The reported cases of infection were due to the ingestion of contaminated fresh fruit, juices, or sugar cane juice. There have been few studies on the physiopathology of the disease in oral transmission cases. Gastritis is a common ailment that can be caused by poor dietary habits, intake of alcohol or other gastric irritants, bacterial infection, or by the widespread use of non-steroidal anti-inflammatory drugs (NSAIDs). This study investigated in a mouse model whether gastric mucosal injury, induced by aspirin, would affect the course of disease in animals infected with T. cruzi by the oral route. The CL14 and G strains of T. cruzi, both of low infectivity, were used. To this end, groups of BALB/c mice were treated during 5 days with aspirin (100 mg kg(-1)) before oral infection with T. cruzi metacyclic forms (4 × 10(5) or 5 × 10(7) parasites/mouse). Histological analysis and determination of nitric oxide and TNF-α were performed in gastric samples obtained 5 days after infection. Parasitemia was monitored from the thirteenth day after infection. The results indicate that aspirin treatment of mice injured their gastric mucosa and facilitated invasion by both CL14 and G strains of T. cruzi. Strain CL14 caused more severe infection compared to the G strain, as larger numbers of amastigote nests were found in the stomach and parasitemia levels were higher. Our study is novel in that it shows that gastric mucosal damage caused by aspirin, a commonly used NSAID, facilitates T. cruzi infection by the oral route.