Alcides Troncoso

Prevention of foodborne listeriosis

Listeria monocytogenes is a foodborne pathogen that can cause serious invasive illness, mainly in certain well-defined high-risk groups, including elderly and immunocompromised patients, pregnant women, newborns and infants. L. monocytogenes primarily causes abortion, septicemia or meningitis. Contaminated meats (such as hot dogs, delicatessen meats and patiota), dairy products and seafood have all been implicated in outbreaks of listeriosis. The public health importance of listeriosis is not always recognized, particularly because listeriosis is a relatively rare disease compared with other common foodborne illnesses such as salmonellosis or botulism. However, because of its high case fatality rate, listeriosis ranks among the most frequent causes of death due to foodborne illness, ranking second after salmonellosis. L. monocytogenes emerged as an important foodborne pathogen in the latter part of the 20th century. Extensive work has been performed in many countries during the last decade to prevent outbreaks and decrease the incidence of listeriosis. An important reduction occurred in listeriosis incidence in some of these countries during the 90s, suggesting a relationship between preventive measures and incidence decrease of human listeriosis.

Listeria monocytogenes outbreaks: A review of the routes that favor bacterial presence

Listeria monocytogenes is a foodborne pathogen that causes serious invasive illness, mainly in certain well-defined high-risk groups, including immunocompromised patients, pregnant women and neonates. L. monocytogenes primarily causes abortion, septicaemia or infections of the central nervous systems. Listeriosis outbreaks have mostly been linked to consumption of raw milk or cheese made of unpasteurized milk. Previous outbreaks of listeriosis have been linked to a variety of foods especially processed meats (such as hot dogs, deli meats, and páté). The public health importance of listeriosis is not always recognized, particularly since listeriosis is a relatively rare disease compared with other common foodborne illnesses such as salmonellosis or botulism. However, because of its high case fatality rate, listeriosis ranks among the most frequent causes of death due to foodborne illness: second after salmonellosis. Changes in the manner food is produced, distributed and stored have created the potential for widespread outbreaks involving many countries. The pasteurization of raw milk, which destroys L. monocytogenes, does not eliminate later risk of L. monocytogenes contamination in dairy products. Extensive work has been ongoing in many countries during the last decade to prevent outbreaks and decrease the incidence of listeriosis. A marked reduction has occurred in its incidence in some of these countries during the 1990s, suggesting a relationship between preventive measures and reduction on human cases listeriosis.

Diagnosis of Mycobacterium tuberculosis using molecular biology technology

OBJECTIVE To present an integrated molecular biology dedicated system for tuberculosis diagnosis. METHODS One hundred and five sputum specimens from patients strongly suspected by clinical parameters of tuberculosis were studied by Ziehl-Neelsen staining, by cultivation on solid medium and by a balanced heminested fluorometric PCR system (Orange G3TB) that could preserve worker safety and produce a rather pure material free of potential inhibitors. DNA amplification was performed in a low cost tuberculosis termocycler-fluorometer. Produced double stranded DNA was flurometrically detected. The whole reaction was conducted in one single tube which would not be opened after adding the processed sample in order to minimize the risk of cross contamination with amplicons. RESULTS The assay was able to detect 30 bacillus per sample mL with 99.8% interassay variation coefficient. PCR was positive in 23 (21.9%) tested samples (21 of them were smear negative). In our study it showed a preliminary sensitivity of 94.5% for sputum and an overall specificity of 98.7%. CONCLUSIONS Total run time of the test is 4 h with 2.5 real working time. All PCR positive samples are also positive by microbiological culture and clinical criteria. Results show that it could be a very useful tool to increase detection efficiency of tuberculosis disease in low bacilus load samples. Furthermore, its low cost and friendly using make it feasible to run in poor regions.

Strongyloides stercoralis Hyperinfection in a Patient With AIDS

Strongyloides stercoralis is a prevalent cause of severe infection and death in many areas of the world where fecal contamination of soil or water is common. The nematode is endemic in tropical and subtropical regions of the world, including northeastern Argentina, where infection rates may exceed 30% of the population. Strongyloides infections are often light and associated with few or no signs and symptoms, particularly during initial migration through the body. However, certain persons are at risk of severe, clinically significant disease developing. The manifestations of hyperinfection syndrome are divided, based on the system of origin, into intestinal and extraintestinal disease mainly involving the respiratory tract. Unfortunately, S stercoralis hyperinfection is seldom diagnosed until late in the course of the disease, which contributes to a high death rate. In patients with the hyperinfection syndrome and massive Strongyloides infection, adult respiratory distress syndrome with pulmonary insufficiency that requires intubation and mechanical ventilation may also develop. We report a case of S stercoralis hyperinfection in an HIV-infected patient, which resulted in death.

CNS Cryptococcoma in an HIV-Positive Patient

This is the first case of brain cryptococcoma in an AIDS patient reported in Argentina. The patient was a 28-year-old white heterosexual man with AIDS who presented with altered mental status, seizures, visual hallucinations, headache, and fever without significant focal neurological deficit. He had a lumbar puncture, and was treated for cryptococcal meningitis. Subsequent brain CT scanning and MRI disclosed a mass lesion in the occipital lobe. Histopathological examination of biopsy was compatible with cryptococcoma, and tissue culture revealed Cryptococcus neoformans. Resolution of the mass and edema resulted after treatment with intravenous amphotericin B for six weeks, which was followed with maintenance oral fluconazole. Intracranial mass is an uncommon complication in AIDS patients with cryptococcosis, and cryptococcoma should be considered as differential diagnosis of brain mass lesion in these patients. The etiologic diagnosis is necessary because central nervous system (CNS) toxoplasmosis, lymphoma, and tuberculoma can produce similar clinical syndromes and MRI or CT findings to cryptococcoma. Also, these pathologies may coexist with meningeal cryptococcosis.

Infections and inequalities: anemia in AIDS, the disadvantages of poverty.

OBJECTIVE To study anemia in AIDS patients and its relation with socioeconomic, employment status and educational levels. METHODS A total number of 442 patients who visited the Infectious Diseases University Hospital in Buenos Aires, Argentina were included in the study. Patients were dividied into two groups, i.e. one with anemia and the other without anemia. Anemia epidemiology and its relationship with educational level, housing, job situation, monthly income, total daily caloric intake and weekly intake of meat were evaluated. RESULTS Anemia was found in 228 patients (54%). Comparing patients with or without anemia, a statistically significant difference was found (P<0.000 1) in those whose highest educational level reached was primary school, who lived in a precarious home, who had no stable job or were unable to work, whose income was less than 30 dollars per month, whose meat consumption was less than twice a week or received less than 8 000 calories per day. CONCLUSIONS The high prevalence of anemia found in poor patients with AIDS suggests that poverty increases the risk to suffer from this hematological complication. The relationship between economic development policies and AIDS is complex. Our results seem to point to the fact that AIDS epidemic may affect economic development and in turn be affected by it. If we consider that AIDS affects the economically active adult population, despite recent medical progress it usually brings about fatal consequences, especially within the poorest sectors of society where the disease reduces the average life expectancy, increases health care demand and tends to exacerbate poverty and iniquity.

Ebola outbreak in West Africa: a neglected tropical disease

Neglected tropical diseases (NTDs) are remediable injustices of our times. Poverty is the starting point, and the ultimate outcome, of NTD. Ebola is just one of many NTDs that badly need attention. Ebola exacerbates West Africas poverty crisis. The virus spreading in Guinea, Liberia and Sierra Leone has led to food shortages and neglect of other devastating tropical illnesses. A health crisis that was ignored for months until it was out of control is now beginning to get the attention required, if not the resources. So far, the worlds nations have contributed far less than the

Giemsa and Grocott in the recognition of Histoplasma capsulatum in blood smears

1 billion. The U.N. estimates would need to control the epidemic before it becomes endemic. Past outbreaks of Ebola have flared up in remote, forested communities, disconnected from much of the outside world. But the outbreak in West Africa has not slowed yet, and it worsens there the chances of it spreading to other countries. Ebola draws attention to NTD. Ebola is not only a health emergency, but also its a poverty crisis. The current Global Ebola crisis presents a multitude of challenges in terms of our capacity to respond; the future is even less predictable. Ebola outbreak represents inequity in health as the occurrence of health differences considered unnecessary, avoidable, unfair, and unjust, thus adding a moral and ethical dimension to health inequalities. Health equity does not refer only to the fairness in the distribution of health or the provision of health care; rather, it is linked with the larger issues of fairness and justice in social arrangements.

Enfermedades transmitidas por los alimentos: Análisis del riesgo microbiológico

OBJECTIVE To facilitate the recognition of intracellular yeasts of Histoplasma capsulatum and differentiate it from Leishmania amastigotes and other parasites, using the combination of Giemsa and a rapid modification of Grocott stains to peripheral blood smears in a hematological study. METHODS The combination of both stains was applied consecutively (first Grocott and then Giemsa) to previously fixed peripheral blood smears. Microscopy was performed with 400× and 1 000×, the latter using immersion oil. RESULTS The yeasts of Histoplasma capsulatum were observed into the cytoplasm of leukocytes as brownish oval elements, with 3-4 µm in diameter. CONCLUSIONS The combination of both techniques is a simple and fast method to facilitate recognition of intracellular yeasts and it is different from intracellular parasitic elements. Moreover, it allows distinguishing the cell elements that are in the microscopic preparations. It may be very helpful in those cases in which the presumptive diagnosis of histoplasmosis has not been established yet and where other more sophisticated methods are not available.

Genital manifestations in women with AIDS.

Las metas basicas del analisis de riesgo incluyen las siguientes: identificar las situaciones potencialmente peligrosas, aplicar los metodos apropiados para estimar la probabilidad que un peligro ocurra, y en la incertidumbre en esa estimacion, proporcionar las soluciones alternativas para reducir el riesgo, estimar la eficacia de esas soluciones, proporcionar la informacion sobre las que se base una decision de la gestion de riesgos, y estimar la incertidumbre asociada a la evaluacion. El analisis de riesgos constituye un sistema de referencia coherente para reunir y analizar indicios sobre los factores de riesgo, y tambien para presentar los resultados de modo inteligible y obrar despues eficazmente. Pero los progresos realizados no pueden excusar la arrogancia. La presente revision no pretende sentar catedra sobre el analisis de riesgo microbiano, mas bien esta pensado como una etapa mas de un proceso necesario y permanente, como un jalon que describe el estado de cosas en 2010.