Mario C. Salinas-Carmona

Mycetoma Medical Therapy

Medical treatment of mycetoma depends on its fungal or bacterial etiology. Clinically, these entities share similar features that can confuse diagnosis, causing a lack of therapeutic response due to inappropriate treatment. This review evaluates the response to available antimicrobial agents in actinomycetoma and the current status of antifungal drugs for treatment of eumycetoma.

Humoral Immunity through Immunoglobulin M Protects Mice from an Experimental Actinomycetoma Infection by Nocardia brasiliensis

ABSTRACT An experimental model of infection with Nocardia brasiliensis, used as an example of a facultative intracellular pathogen, was tested. N. brasiliensis was injected into the rear foot pads of BALB/c mice to establish an infection. Within 30 days, infected animals developed a chronic actinomycetoma infection. Batch cultures of N. brasiliensis were used to purify P61, P38, and P24 antigens; P61 is a catalase, and P38 is a protease with strong caseinolytic activity. Active and passive immunizations of BALB/c mice with these three purified soluble antigens were studied. Protection was demonstrated for actively immunized mice. However, immunity lasted only 30 days. Other groups of immunized mice were bled at different times, and their sera were passively transferred to naive recipients that were then infected with N. brasiliensis. Sera collected 5, 6, and 7 days after donor immunization conferred complete, long-lasting protection. The protective effect of passive immunity decreased when sera were collected 2 weeks after donor immunization. However, neither the early sera (1-, 2-, and 3-day sera) nor the later sera (30- or 45-day sera) prevented the infection. Hyperimmune sera with the highest levels of immunoglobulin G (IgG) to N. brasiliensis antigens did not protect at all. The antigens tested induced two IgM peaks. The first peak was present 3 days after immunization but was not antigen specific and did not transfer protection. The second peak was evident 7 days after immunization, was an IgM response, was antigen specific, and conferred protection. This results clearly demonstrate that IgM antibodies protect the host against a facultative intracellular bacterium.

Soluble RAGE as a severity marker in community acquired pneumonia associated sepsis

BackgroundCommunity-acquired pneumonia (CAP) is considered the most important cause of death from infectious disease in developed countries. Severity assessment scores partially address the difficulties in identifying high-risk patients. A lack of specific and valid pathophysiologic severity markers affect early and effective sepsis therapy. HMGB-1, sRAGE and RAGE have been involved in sepsis and their potential as severity markers has been proposed. The aim of this study was to evaluate HMGB-1, RAGE and sRAGE levels in patients with CAP-associated sepsis and determine their possible association with clinical outcome.MethodWe evaluated 33 patients with CAP-associated sepsis admitted to the emergency room and followed in the medical wards. Severity assessment scores (CURB-65, PSI, APACHE II, SOFA) and serologic markers (HMGB-1, RAGE, sRAGE) were evaluated on admission.ResultsThirty patients with a diagnosis of CAP-associated sepsis were enrolled in the study within 24 hours after admission. Fourteen (46.6%) had pandemic (H1N1) influenza A virus, 2 (6.6%) had seasonal influenza A and 14 other diagnoses. Of the patients in the study group, 16 (53.3%) had a fatal outcome. ARDS was observed in 17 (56.6%) and a total of 22 patients had severe sepsis on admission (73%). The SOFA score showed the greatest difference between surviving and non-surviving groups (P = .003) with similar results in ARDS patients (P = .005). sRAGE levels tended to be higher in non-surviving (P = .058) and ARDS patients (P = .058). Logistic regression modeling demonstrated that SOFA (P = .013) and sRAGE (P = .05) were the only variables that modified the probability of a fatal outcome.ConclusionThe association of elevated sRAGE with a fatal outcome suggests that it may have an independent causal effect in CAP. SOFA scores were the only clinical factor with the ability to identify surviving and ARDS patients.

Spontaneous arthritis in MRL/lpr mice is aggravated by Staphylococcus aureus and ameliorated by Nippostrongylus brasiliensis infections

Rheumatoid arthritis is an autoimmune disease that affects human beings worldwide. Infections have been associated to autoimmune diseases because their ability to induce a dominant cytokine response. Joint inflammation has been related to Th1 response because they induce high expression of proinflammatory cytokines TNF-α, IL-1, IFN-γ. MRL/lpr mice spontaneously develop an autoimmune disease affecting joints, kidneys, etc. We compared incidence and severity of arthritis, antibody response, cytokine production, in mice infected with bacteria or helminthes in the Murphy Roths Large (MRL)lpr mice. Infections with helminthes Heligmosomoides polygyrus, Nippostrongylus brasiliensis or bacteria Nocardia brasiliensis and Staphylococcus aureus were studied. IL-4, IFN-γ and IgG1, IgG2a antibody productions were determined. IFN-γ was increased in all groups, the highest production was observed after bacterial infection; IL-4 production was higher after helminthes infection. IgG1 sera levels were increased in the helminthes infected group. IgG2a sera concentration was stimulated by bacterial infection. The histopathology showed that 100% of bacterial infected mice developed arthritis and severe tissue damage such as cartilage erosion and bone destruction. Animals infected with parasites showed a decreased incidence and severity of arthritis. Severity of tissue damage in joints is correlated with increased numbers of lymphocytes and macrophages immunoreactive to proinflammatory cytokines.

Immunosuppressive drugs have different effect on B lymphocyte subsets and IgM antibody production in immunized BALB/c mice

Infections are frequently associated with immunosuppressive therapy currently used to prevent organ rejection or treat autoimmune diseases. Such drugs suppress antibody production despite having different mechanisms of action. Antibodies are produced by a non-homogenous population of B lymphocyte subsets. B-1 cells produce natural antibodies and protect immediately after infection, while B2 cells produce antigen-specific IgM antibodies in a later response to infection. To understand how the immunosuppressive drugs affect antibody production by B cell populations, we immunized BALB/c mice with different antigens followed by administration of various immunosuppressive drugs. B-1a and B-1b lymphocytes from spleens of sacrificed animals were analyzed by flow cytometry, natural and antigen –specific IgG and IgM antibodies were determined by nephelometry and ELISA assays. Results showed that prednisone (PDN), cyclophosphamide (CYC), methotrexate (MTX), mycophenolate mofetil (MMF) and azathioprine (AZA) decreased more than 60% of B-1a lymphocytes while cyclosporine (CsA) had little effect. Three drugs PDN, AZA and CYC suppressed the B-2 cells on day 30, while MTX affected this subpopulation early on day 5. Antigen-specific IgM antibodies were dramatically suppressed after 15 days of immunization in animals receiving PDN, CYC or AZA, while MMF, CsA and MTX showed little effect. Natural antibodies were equally decreased in all animals regardless of the specific drug used in treatment. These results will help to choose single or combinations of immunosuppressive drugs in the clinical setting.

Current treatment for nocardia infections

Introduction: Nocardiosis is an infectious actinomycetic disease with a variable clinical spectrum that makes it difficult to diagnose. It mainly affects immunosuppressed individuals. Advances in molecular genomic technology have helped in identifying new pathogenic Nocardia species. This has made identification of their specific antimicrobial sensitivity possible. Areas covered: It is important to know the taxonomy, clinical features, diagnosis and precise species identification because of the multitude of pathogenic species involved and the different antibiotic susceptibility patterns. The authors review sulfonamides, aminoglycosides, penicillin derivatives, tetracyclines, glycylcyclines, oxazolidinones, carbapenems and the association of other potential drugs, the therapeutic effectiveness of traditional antimicrobials and new monotherapy and combined treatment alternatives. New oxazolidinones and the benzothiazinones are compounds that have been found effective in vitro and in experimental models. Expert opinion: Clinicians should be aware of nocardiosis in patients with different forms of immunosuppression. The identification of organisms, their patterns of antibiotic susceptibility and the adverse effects related to these drugs must be considered. Treatments can vary from traditional schemes with trimethoprim–sulfamethoxazole to other combination therapies and new antibiotics and treatment modalities depending on the organ or site involved, the severity of infection and the presence of comorbidities.

Development of a novel trap for the collection of black flies of the Simulium ochraceum complex.

Background Human landing collections are currently the standard method for collecting onchocerciasis vectors in Africa and Latin America. As part of the efforts to develop a trap to replace human landing collections for the monitoring and surveillance of onchocerciasis transmission, comprehensive evaluations of several trap types were conducted to assess their ability to collect Simulium ochraceum sensu lato, one of the principal vectors of Onchocerca volvulus in Latin America. Methodology/Principal Findings Diverse trap designs with numerous modifications and bait variations were evaluated for their abilities to collect S. Ochraceum s.l. females. These traps targeted mostly host seeking flies. A novel trap dubbed the “Esperanza window trap” showed particular promise over other designs. When baited with CO2 and BG-lure (a synthetic blend of human odor components) a pair of Esperanza window traps collected numbers of S. Ochraceum s.l. females similar to those collected by a team of vector collectors. Conclusions/Significance The Esperanza window trap, when baited with chemical lures and CO2 can be used to collect epidemiologically significant numbers of Simulium ochraceum s.l., potentially serving as a replacement for human landing collections for evaluation of the transmission of O. volvulus.

Nocardia brasiliensis Cell Wall Lipids Modulate Macrophage and Dendritic Responses That Favor Development of Experimental Actinomycetoma in BALB/c Mice

ABSTRACT Nocardia brasiliensis is a Gram-positive facultative intracellular bacterium frequently isolated from human actinomycetoma. However, the pathogenesis of this infection remains unknown. Here, we used a model of bacterial delipidation with benzine to investigate the role of N. brasiliensis cell wall-associated lipids in experimental actinomycetoma. Delipidation of N. brasiliensis with benzine resulted in complete abolition of actinomycetoma without affecting bacterial viability. Chemical analyses revealed that trehalose dimycolate and an unidentified hydrophobic compound were the principal compounds extracted from N. brasiliensis with benzine. By electron microscopy, the extracted lipids were found to be located in the outermost membrane layer of the N. brasiliensis cell wall. They also appeared to confer acid-fastness. In vitro, the extractable lipids from the N. brasiliensis cell wall induced the production of the proinflammatory cytokines interleukin-1β (IL-1β), IL-6, and CCL-2 in macrophages. The N. brasiliensis cell wall extractable lipids inhibited important macrophage microbicidal effects, such as tumor necrosis factor alpha (TNF-α) and nitric oxide (NO) production, phagocytosis, bacterial killing, and major histocompatibility complex class II (MHC-II) expression in response to gamma interferon (IFN-γ). In dendritic cells (DCs), N. brasiliensis cell wall-associated extractable lipids suppressed MHC-II, CD80, and CD40 expression while inducing tumor growth factor β (TGF-β) production. Immunization with delipidated N. brasiliensis induced partial protection preventing actinomycetoma. These findings suggest that N. brasiliensis cell wall-associated lipids are important for actinomycetoma development by inducing inflammation and modulating the responses of macrophages and DCs to N. brasiliensis.

Expression of CD64, CD206, and RAGE in Adherent Cells of Diabetic Patients Infected with Mycobacterium tuberculosis

BACKGROUND CD64 and CD206 receptors play an important role in the internalization of Mycobacterium tuberculosis into macrophages. RAGE, described in diabetes (a predisposing factor for tuberculosis), captures glycosylated proteins. METHODS Four groups of 15 patients with type 2 diabetes mellitus (DM2), pulmonary tuberculosis (PTB), type 2 diabetes and pulmonary tuberculosis (DM2-PTB), and controls (CG) were studied. Blood was obtained and mononuclear cells (MNC) isolated and cultured to obtain adherent cells (AC) and then stimulated with M. tuberculosis H37Rv lipids. Expression of CD64, CD206 and RAGE was measured by flow cytometry. RESULTS In the groups without stimulus, PTB and DM2-PTB expressed greater mean fluorescence intensity (MFI) of CD64 and CD206 compared to CG. DM2-PTB showed a decrease in expression compared to PTB. After lipid stimulation no significant difference between groups occurred. In AC without stimulus, RAGE expression was significantly greater in DM2, PTB and DM2-PTB. When DM2-PTB was compared to PTB, a significant decrease in expression occurred. After lipid stimulation, only DM2 cells showed greater MFI. CONCLUSIONS Diabetes affects expression of the three receptors. PTB cells significantly increase them. Diabetes and tuberculosis infection decrease expression compared to PTB alone. Diabetes did not alter CD64 and CD206 expression in infected patients. RAGE expression increases in patients with PTB as well as in diabetics. This suggests that RAGE could also behave as a receptor for M. tuberculosis.

Antibody response to Nocardia brasiliensis antigens in man.

A crude extract from N. brasiliensis cells grown in brain heart infusion culture was analyzed. It showed a complex mixture of at least 37 bands when resolved with the discontinuous buffer system of Laemmli in a gradient SDS-PAGE. Western blot analysis of 16 sera from N. brasiliensis-infected individuals always showed the recognition of six bands of 61, 49, 45, 42, 26, and 24 kilodaltons (kDa). Some other bands also reacted but with less intensity. Sera from tuberculosis and leprosy patients reacted strongly with the 49, 45, and 42 kDa bands but weakly or not at all with the 61, 26, and 24 kDa. Sera from healthy control volunteers reacted with some bands but little or not at all with those three identified by the sera from mycetoma patients. These three immunodominant antigens (61, 26 and 24 kDa) may be of clinical value in the serodiagnosis of mycetoma by N. brasiliensis.