Antimony toxicity upon microorganisms from aerobic and anaerobic environments.

Antimony (Sb) is a toxic and carcinogenic metalloid that can be present in contaminated water generated by mining operations and other industrial activities. The toxicity of Sb (III) and Sb (V) to aerobic microorganisms remains limited and unexplored for anaerobic microorganisms involved in hydrogen (H2) and methane (CH4) production. This study aimed to evaluate the toxicity of Sb (III) and Sb (V) upon aerobic and anaerobic microorganisms important in biological wastewater treatment systems. Sb (III) was more toxic than Sb (V) independently of the test and environment evaluated. Under aerobic conditions maintained in the Microtox assay, Sb (V) was not toxic to Allivibrio fischeri at concentrations as high as 500 mg/L, whereas Sb (III) caused just over 50% inhibition at concentration of 250 mg/L after 5 min of exposure. In the respirometry test, for the specific oxygen uptake rate, the concentrations of Sb (III) and Sb (V) displaying 50% inhibition were 0.09 and 56.2 mg/L, respectively. Under anaerobic conditions, exposure to Sb (III) and Sb (V) led to a decrease in microorganisms activity of fermentative and methanogenic processes. The results confirm that the microbial toxicity of Sb depends on its speciation and Sb (III) displays a significantly higher inhibitory potential than Sb (V) in both aerobic and anaerobic environments.

Clinical case of cerebral amebiasis caused by E. histolytica.

Although amebic brain abscess is a rare form of invasive amebiasis, when present, it is frequently lethal. This disorder always begins with the infection of the colon by Entamoeba histolytica trophozoites, which then travel to extra-intestinal tissues through the bloodstream. Amebic brain abscesses are produced when trophozoites invade the central nervous system. Computerized axial tomography scans can be used to diagnose the presence or absence of a brain abscess with a certainty of 100%. However, this diagnostic tool does not reveal the etiological agent of disease. By analyzing the clinical case of a patient that died due to untimely treatment of this malady, the present study aims to identify a diagnostic tool that can give a precise determination of the etiological agent and therefore permit adequate and opportune treatment. Currently, diagnosis of amebic brain abscess is often done by identification of the ameba in a biopsy or autopsy. By immunohistochemistry and immunofluorescence with specific antibodies, we identified the existence of E. histolytica, which presents proteins similar to Naegleria fowleri in its membrane.