Selenium Removal from Wastewater by Microbial Transformation and Volatilization.

Selenium (Se) is a naturally occurring trace element that is nutritionally essential for humans and animals, but becomes toxic at high concentrations. This laboratory study explored the role of microbes in Se removal from contaminated wastewater via biological transformation and volatilization processes. Microbes could immobilize water-soluble selenate (SeO42-) and selenite (SeO32-) to water-insoluble elemental Se (Se0) and transform Se into volatile Se compounds found in the atmosphere. Results of this laboratory study showed that Bacillus cereus, a bacterial strain isolated from wheat straw and biosolid-WTR-sand substrates showed a significant biotransformation ability of reducing selenate and selenite to elemental Se and forming volatile Se organic compounds in wastewater. Overall, microbial Se chemical reduction, methylation, and volatilization are important processes in bioremediation of Se-contaminated wastewater.

Topographic constraints on the distribution of selenium in the supergene environment: A case study at Yutangba, China.

The local topography and leaching conditions significantly affect the spatial distribution of selenium (Se) in the local environment. However, the driving factors controlling Se distribution have not been well addressed. In this paper, taking Yutangba, a village known for human selenosis in China, as an example, we demonstrate how topographic factors influence the spatial distribution of Se in soils and plants. In the scenarios of slope ≤25°, the correlations among slope and soil/extractable/plant Se are significantly negative (P < 0.05), whereas they become weak or unclear when the slope is > 25°, suggesting that 25° of slope is a critical transition boundary. Similar observations were further verified by the soil erosion modulus (SEM) and the surface runoff intensity index (SRI), indicating that Se transport via soil erosion is limited and accounts for 11.2-17% of the soil Se, while surface runoff plays a dominant role in the Se distribution, accounting for 83-88.1%. Soil extractable Se is negatively correlated with SRI (Pearson r = -0.87 at slope < 25°), showing that the migration capacity of Se is higher at steep terrain and controlled by topography through soil erosion and surface runoff. The positive relationship between plant Se and soil/extractable Se demonstrates that topography indirectly influences plant Se through soil Se bioavailability. Abnormally local Se enrichment observed at the elevated steep hillside (>25°) in northwestern Yutangba primarily was resulted from the weathering of Se-rich rocks. These observations confirm that the topographic slope gradient influences the transport and spatial distribution of soil Se, implying that topography should be considered when studying the spatial distribution of soil Se at a regional scale, especially for the Se-poor belt in China.

Synergistic Effect of Melatonin and Selenium Improves Resistance to Postharvest Gray Mold Disease of Tomato Fruit.

Melatonin (MT) is a ubiquitous hormone molecule that is commonly distributed in nature. MT not only plays an important role in animals and humans but also has extensive functions in plants. Selenium (Se) is an essential micronutrient for animals and humans, and is a beneficial element in higher plants at low concentrations. Postharvest diseases caused by fungal pathogens lead to huge economic losses worldwide. In this study, tomato fruits were treated with an optimal sodium selenite (20 mg/L) and melatonin (10 µmol/L) 2 h and were stored for 7 days at room temperature simulating shelf life, and the synergistic effects of Se and MT collectively called Se-Mel on gray mold decay in tomato fruits by Botrytis cinerea was investigated. MT did not have antifungal activity against B. cinerea in vitro, while Se significantly inhibited gray mold development caused by B. cinerea in tomatoes. However, the interaction of MT and Se showed significant inhibition of the spread and growth of the disease, showing the highest control effect of 74.05%. The combination of MT with Se treatment enhanced the disease resistance of fruits by improving the activities of superoxide dismutase (SOD), peroxidase (POD), and catalase (CAT), as well as increasing the gene expression level of pathogenesis-related (PR) proteins. Altogether, our results indicate that the combination of MT and Se would induce the activation of antioxidant enzymes and increase the expression of PR proteins genes that might directly enhance the resistance in tomato fruit against postharvest pathogenic fungus B. cinerea.

Selenium Effect Threshold for Soil Nematodes Under Rice Biofortification.

Crop biofortification with inorganic selenium (Se) fertilizer is a feasible strategy to improve the health of residents in Se-deficient areas. For eco-friendly crop Se biofortification, a comprehensive understanding of the effects of Se on crop and soil nematodes is vital. In this study, a rice pot experiment was carried out to test how selenite supply (untreated control (0), 5, 10, 15, 20, 25, 30, 35, 40, 45, 50, 100, or 200 mg Se kg-1) in soil affected rice growth, rice Se accumulation, and soil nematode abundance and composition. The results showed that selenite supply (5-200 mg kg-1) generally increased the number of rice tillers, rice yield, and Se concentrations in rice grains. In soil under 10 mg kg-1 Se treatment, the genus composition of nematodes changed significantly compared with that in the control soil. With increased Se level (> 10 mg kg-1), soil nematode abundance decreased significantly. Correlation analysis also demonstrated the positive relationships between soil Se concentrations (total Se and bioavailable Se) with rice plant parameters (number of rice tillers, rice yield, and grain Se concentration) and negative relationships between soil Se concentrations (total Se and bioavailable Se) with soil nematode indexes (nematode abundance and relative abundance of Tobrilus). This study provides insight into balancing Se biofortification of rice and soil nematode community protection and suggests the effective concentrations for total Se (1.45 mg kg-1) and bioavailable Se (0.21 mg kg-1) to soil nematode abundances at 20% level (EC20) as soil Se thresholds. At Se concentrations below these thresholds, rice plant growth and Se accumulation in the grain will still be promoted, but the disturbance of the soil nematodes would be negligible.

Zero-Valent Iron Nanoparticles Remediate Nickel-Contaminated Aqueous Solutions and Biosolids-Amended Agricultural Soil.

Nickel (Ni+2) accumulation in wastewater treatment sludge poses a potential environmental risk with biosolids-land application. An incubation experiment was conducted to evaluate the effect of nanoparticles of zero-valent iron (nZVI) on Ni+2 sorption in biosolids-treated agricultural soils. Two application rates of biosolids (0, 5%, w/w) and four treatment levels (0, 1, 5, and 10 g/kg) of nZVI were examined, either separately or interactively. The results of this study showed significant differences in Ni+2 sorption capacity between different nZVI treatments. The initial Ni+2 concentration in biosolids-amended soil significantly affected Ni sorption in the soil treated with nZVI. The "H-shape" of sorption isotherm in nZVI-treated soil reflects strong interaction between the Ni concentration and the nZVI treatment, while the C-shape of sorption isotherm in biosolids-amended soil without the nZVI treatment indicates intermediate affinity for Ni+2 sorption. Nickel retention in soil was increased with the increase of nZVI levels. The removal efficiency of Ni+2 by nZVI from solution was increased with the increase of pH from 5 to 11 and reached a maximum of 99.56% at pH 11 and nZVI treatment of 10 g/kg. The Ni+2 desorption rate decreased from 92 to 7, 4, and 1% with increasing nZVI treatment levels from 0 to 1, 5, and 10 g/kg, respectively, with a soil Ni+2 concentration of 50 mg/L. The maximum adsorption capacity (?max) of 10 g/kg nZVI-treated soil was 333.3 mg/g, which was much higher than those from the other treatments of 0 (5 mg/g), 1 (25 mg/g), and 5 g/kg (125 mg/g). The underlying mechanism for Ni+2 immobilization using nZVI in an aquatic environment is controlled by a sorption process, reduction of metal ion to zero-valent metal, as well as (co)precipitation. Moreover, increasing the nZVI treatment level in biosolids-amended soil significantly decreased bioavailable Ni+2 concentrations in the soil.

[Clinical features and treatment of macrolide-resistant Mycoplasma pneumoniae pneumonia in children].

OBJECTIVE: To study the clinical features of macrolide-resistant Mycoplasma pneumoniae pneumonia and its treatment regimens in children. METHODS: The samples of throat swab or bronchoalveolar lavage fluid were collected from 136 children with Mycoplasma pneumoniae pneumonia. Quantitative real-time PCR was used to detect 2063/2064 A:G mutation in 23S rRNA, and according to such results, the children were divided into drug-resistance group with 81 children and sensitive group with 55 children. The two groups were compared in terms of age composition, respiratory symptoms, extrapulmonary complications, laboratory markers, imaging changes, treatment regimens, and length of hospital stay. RESULTS: Compared with the sensitive group, the drug-resistance group had significantly longer duration of pyrexia and severe fever, a significantly higher percentage of children with reduced blood oxygen saturation, and significantly higher levels of alanine aminotransferase (ALT) and lactate dehydrogenase (LDH) (P<0.05). The conventional azithromycin treatment had a good clinical effect in the sensitive group, while corticosteroid therapy was usually needed in the drug-resistance group. CONCLUSIONS: Macrolide-resistant Mycoplasma pneumoniae infection cannot be identified based on a single clinical feature, but prolonged duration of pyrexia and severe fever, reduced blood oxygen saturation, and increased ALT and LDH can suggest the presence of this disease. Azithromycin combined with glucocorticoids may be a good treatment regimen for children with macrolide-resistant Mycoplasma pneumoniae pneumonia.

Selenium speciation in seleniferous agricultural soils under different cropping systems using sequential extraction and X-ray absorption spectroscopy.

Selenium (Se) speciation in soil is critically important for understanding the solubility, mobility, bioavailability, and toxicity of Se in the environment. In this study, Se fractionation and chemical speciation in agricultural soils from seleniferous areas were investigated using the elaborate sequential extraction and X-ray absorption near-edge structure (XANES) spectroscopy. The speciation results quantified by XANES technique generally agreed with those obtained by sequential extraction, and the combination of both approaches can reliably characterize Se speciation in soils. Results showed that dominant organic Se (56-81% of the total Se) and lesser Se(IV) (19-44%) were observed in seleniferous agricultural soils. A significant decrease in the proportion of organic Se to the total Se was found in different types of soil, i.e., paddy soil (81%) > uncultivated soil (69-73%) > upland soil (56-63%), while that of Se(IV) presented an inverse tendency. This suggests that Se speciation in agricultural soils can be significantly influenced by different cropping systems. Organic Se in seleniferous agricultural soils was probably derived from plant litter, which provides a significant insight for phytoremediation in Se-laden ecosystems and biofortification in Se-deficient areas. Furthermore, elevated organic Se in soils could result in higher Se accumulation in crops and further potential chronic Se toxicity to local residents in seleniferous areas.

Indications of Selenium Protection against Cadmium and Lead Toxicity in Oilseed Rape (Brassica napus L.).

The present study investigated the beneficial role of selenium (Se) in protecting oilseed rape (Brassica napus L.) plants from cadmium (Cd+2) and lead (Pb+2) toxicity. Exogenous Se markedly reduced Cd and Pb concentration in both roots and shoots. Supplementation of the medium with Se (5, 10, and 15 mg kg-1) alleviated the negative effect of Cd and Pb on growth and led to a decrease in oxidative damages caused by Cd and Pb. Furthermore, Se-enhanced superoxide free radicals ([Formula: see text]), hydrogen peroxide (H2O2), and lipid peroxidation, as indicated by malondialdehyde accumulation, but decreased superoxide dismutase and glutathione peroxidase activities. Meanwhile, the presence of Cd and Pb in the medium affected Se speciation in shoots. The results suggest that Se could alleviate Cd and Pb toxicity by preventing oxidative stress in oilseed rape plant.

Biofortification and phytoremediation of selenium in China.

Selenium (Se) is an essential trace element for humans and animals but at high concentrations, Se becomes toxic to organisms due to Se replacing sulfur in proteins. Selenium biofortification is an agricultural process that increases the accumulation of Se in crops, through plant breeding, genetic engineering, or use of Se fertilizers. Selenium phytoremediation is a green biotechnology to clean up Se-contaminated environments, primarily through phytoextraction and phytovolatilization. By integrating Se phytoremediation and biofortification technologies, Se-enriched plant materials harvested from Se phytoremediation can be used as Se-enriched green manures or other supplementary sources of Se for producing Se-biofortified agricultural products. Earlier studies primarily aimed at enhancing efficacy of phytoremediation and biofortification of Se based on natural variation in progenitor or identification of unique plant species. In this review, we discuss promising approaches to improve biofortification and phytoremediation of Se using knowledge acquired from model crops. We also explored the feasibility of applying biotechnologies such as inoculation of microbial strains for improving the efficiency of biofortification and phytoremediation of Se. The key research and practical challenges that remain in improving biofortification and phytoremediation of Se have been highlighted, and the future development and uses of Se-biofortified agricultural products in China has also been discussed.

Effect of Selenium on Control of Postharvest Gray Mold of Tomato Fruit and the Possible Mechanisms Involved.

Selenium (Se) has important benefits for crop growth and stress tolerance at low concentrations. However, there is very little information on antimicrobial effect of Se against the economically important fungus Botrytis cinerea. In the present study, using sodium selenite as Se source, we investigated the effect of Se salts on spore germination and mycelial growth of the fungal pathogen in vitro and gray mold control in harvested tomato fruit. Se treatment at 24 mg/L significantly inhibited spore germination of the fungal pathogen and effectively controlled gray mold in harvested tomato fruit. Se treatment at 24 mg/L seems to induce the generation of intracellular reactive oxygen species in the fungal spores. The membrane integrity damage was observed with fluorescence microscopy following staining with propidium iodide after treatment of the spores with Se. These results suggest that Se has the potential for controlling gray mold rot of tomato fruits and might be useful in integrated control against gray mold disease of postharvest fruits and vegetables caused by B. cinerea. The mechanisms by which Se decreased gray mold decay of tomato fruit may be directly related to the severe damage to the conidia plasma membrane and loss of cytoplasmic materials from the hyphae.

Inhibitory effect of selenium against Penicillium expansum and its possible mechanisms of action.

Some organic and inorganic salts could inhibit the growth of many pathogens. Selenium (Se), as an essential micronutrient, was effective in improving the plant resistance and antioxidant capacity at a low concentration. Penicillium expansum is one of the most important postharvest fungal pathogens, which can cause blue mold rot in various fruits and vegetables. In this study, the inhibitory effect of Se against P. expansum was evaluated. The result showed that Se strongly inhibited spore germination, germ tube elongation, and mycelial spread of P. expansum in the culture medium. The inhibitory effect was positively related to the concentration of Se used. Fluorescence microscopy observation of P. expansum conidia stained with propidium iodide (PI) indicated that the membrane integrity decreased to 37 % after the conidia were treated with Se (20 mg/l) for 9 h. With the use of an oxidant-sensitive probe 2,7-dichlorofluorescin (DCHF-DA), we found that Se at 15 mg/l could induce the generation of intracellular reactive oxygen species (ROS). Furthermore, methane dicarboxylic aldehyde (MDA) content, hydrogen peroxide (H2O2), and superoxide anion (O2 (-)) production rate in P. expansum spores exposed to Se increased markedly. Compared with the control, the activities of superoxide dismutase (SOD) and the content of glutathione (GSH) were reduced, confirming that damage of Se to cellular oxygen-eliminating system is the main reason. These results suggest that Se might serve as a potential alternative to synthetic fungicides for the control of the postharvest disease of fruit and vegetables caused by P. expansum.

Development of a constructed wetland water treatment system for selenium removal: incorporation of an algal treatment component.

On the basis of the fact that algae have the ability to volatilize substantial quantities of selenium (Se), we investigated the concept of including an algal pretreatment unit into a constructed wetland system for the removal of Se from river water entering the Salton Sea. Of six different algal strains tested, the most effective in terms of Se volatilization and Se removal from the water column was a Chlorella vulgaris strain (designated Cv). Cv removed 96% of Se (supplied as selenate) from the microcosm water column within 72 h, with up to 61% being removed by volatilization to the atmosphere. X-ray absorption spectroscopy revealed that the major forms of Se likely to be accumulated in an algal-wetland system are selenomethionine, a precursor of volatile Se formation, and elemental Se. Our results suggest that the inclusion of an algal pretreatment unit within a constructed wetland water treatment system should not only enhance the efficiency of Se removal but also significantly reduce the risk of the buildup of ecotoxic forms of Se by promoting the biological volatilization of Se.

A novel selenocystine-accumulating plant in selenium-mine drainage area in Enshi, China.

Plant samples of Cardamine hupingshanesis (Brassicaceae), Ligulariafischeri (Ledeb.) turcz (Steraceae) and their underlying top sediments were collected from selenium (Se) mine drainage areas in Enshi, China. Concentrations of total Se were measured using Hydride Generation-Atomic Fluorescence Spectrometry (HG-AFS) and Se speciation were determined using liquid chromatography/UV irradiation-hydride generation-atomic fluorescence spectrometry (LC-UV-HG-AFS). The results showed that C. hupingshanesis could accumulate Se to 239±201 mg/kg DW in roots, 316±184 mg/kg DW in stems, and 380±323 mg/kg DW in leaves, which identifies it as Se secondary accumulator. Particularly, it could accumulate Se up to 1965±271 mg/kg DW in leaves, 1787±167 mg/kg DW in stem and 4414±3446 mg/kg DW in roots, living near Se mine tailing. Moreover, over 70% of the total Se accumulated in C. hupingshanesis were in the form of selenocystine (SeCys2), increasing with increased total Se concentration in plant, in contrast to selenomethionine (SeMet) in non-accumulators (eg. Arabidopsis) and secondary accumulators (eg. Brassica juncea), and selenomethylcysteine (SeMeCys) in hyperaccumulators (eg. Stanleya pinnata). There is no convincing explanation on SeCys2 accumulation in C. hupingshanesis based on current Se metabolism theory in higher plants, and further study will be needed.

Single wall carbon nanotube induced inflammation in cruor-fibrinolysis system.

OBJECTIVE: To study single wall carbon nanotubes (SWCNT) and its role in inducing inflammatory cytokines in the cruor-fibrinolysis system of rat. METHODS: Twenty one Wistar rats were divided into four groups: 1) control; 2) low-dose SWCNT (0.15 mg/kg BW); 3) medium-dose SWCNT (0.75 mg/kg BW); 4) high-dose SWCNT (1.5 mg/kg BW). Intratracheal instillation of SWCNT suspensions was administered to rats once per day for 21 days. In order to assess the exposure effect of SWCNT to the rats, activity of Inflammatory cytokine was measured and markers of cruor-fibrinolysis system were studied via ELSIA. Also, change in clotting time was recorded and histopathology was studied. RESULTS: IL-6 and IL-8 concentrations of rats exposed to SWCNT were significantly higher than those in controls (P<0.05). The activity of inflammatory cytokines and histopathological change indicated that oxidative damage occurred. Change in clotting time in rats exposed to SWCNT decreased compared with controls. Meanwhile, t-PA (tissue-tupe plassminogen activator) and AT-III (antithrombin-III) levels in rats exposed to particulates increased or decreased significantly compared with controls (P<0.05). A similar trend was observed for D-dimer (D2D) levels, indicating that SWCNT can impact the cruor-fibrinolysis system of rat. CONCLUSION: The results from our study suggest that an increased procoagulant activity and reduced fibrinolytic activity in rats exposed to SWCNT can cause pulmonary oxidative stress and inflammation, due to the release of pro-thrombotic and inflammatory cytokines into the blood circulation of rat.

Impact of traffic emissions on local air quality and the potential toxicity of traffic-related particulates in Beijing, China.

OBJECTIVE: Air-borne particulates from different sources could have different physicochemical properties and inflammatory potentials. This study aims to characterize the chemical compositions and the toxicity of ambient particulate matter (PM) associated with traffic emissions. METHODS: The concentrations of trace elements, organic carbon (OC), elemental carbon (EC) and polycyclic aromatic hydrocarbons (PAHs) in PM2.5 and PM10 were measured in samples collected at sites in Beijing, China. Their toxic effects on the pulmonary system of rats were investigated. Biochemical parameters (LDH, T-AOC, TP) and inflammatory cytokine(IL-6, IL-1, TNF-a) levels were measured in the lungs of rats exposed to traffic-related PM. Oxidative damage was observed. PM samples were taken from a near road site and an off road site in summer time in 2006. RESULTS: The concentrations of the USEPA priority pollutant PAHs in both PM10 and PM2.5 were higher (299.658 and 348.412) at the near road site than those (237.728 and 268.472) at the off road site. The similar trend was observed for the concentrations of trace elements in PM. Compared to coarse particles (PM10), fine particles (PM2.5) have a greater adsorption capacity to enrich toxic elements than inhalable particles. Decrease in antioxidant capacity and an increase in the amount of lipid peroxidation products in rat lung tissues was observed. CONCLUSION: The findings of the present study suggest that the differing inflammatory responses of PM collected from the two road sites might have been mediated by the differing physicochemical characteristics.

Human Health Risk Assessment of 16 Priority Polycyclic Aromatic Hydrocarbons in Soils of Chattanooga, Tennessee, USA.

South Chattanooga has been home to foundries, coke furnaces, chemical, wood preserving, tanning and textile plants for over 100 years. Most of the industries were in place before any significant development of residential property in the area. During the 1950s and 1960s, however, the government purchased inexpensive property and constructed public housing projects in South Chattanooga. Many neighborhoods that surround the Chattanooga Creek were previous dumping grounds for industry. Polycyclic aromatic hydrocarbons (PAHs) comprised the largest component of the dumping and airborne industrial emissions. To address the human exposure to these PAHs, a broad study of South Chattanooga soil contaminant concentrations was conducted on 20 sites across the city. Sixteen priority pollutant PAHs were quantified at two depths (0-10cm and 10-20cm) and compared against reference site soils, as well as to soils from industrially-impacted areas in Germany, China, and the US. From these data, the probability that people would encounter levels exceeding EPA Residential Preliminary Remediation Goals (PRG) was calculated. Results indicate that South Chattanooga soils have relatively high concentrations of total PAHs, specifically Benzo[a]pyrene (B[a]P). These high concentrations of B[a]P were somewhat ubiquitous in South Chattanooga. Indeed, there is a high probability (88%) of encountering soil in South Chattanooga that exceeds the EPA PRG for B[a]P. However, there is a low probability (15%) of encountering a site with ∑PAHs exceeding EPA PRG guidelines.

Single-wall carbon nanotubes induce oxidative stress in rat aortic endothelial cells.

Oxidative stress is a major factor contributing to endothelial cell damage. Single-wall carbon nanotubes (SWCNTs) have oxidative properties; however, the oxidative effects of SWCNTs on endothelial cells are not fully understood. In the present study, we investigated the effects of oxidative stress induced by SWCNTs on rat aortic endothelial cells (RAECs). Various markers of cellular damage were assessed, such as biochemical and ES immunity indexes, and DNA and protein damage. Our findings suggest that RAEC endured oxidative damage following SWCNT exposure. Specifically, after SWCNTs exposure, non-enzymatic antioxidant glutathione was activated prior to superoxide dismutase activation in order to defend against oxidative stress. Additionally, it was found that as SWCNT concentration increased, so did the stress protein, heme oxygenase-1 (HO-1), expression levels. These changes may induce RAEC damage, and result in many serious diseases.

Single-walled carbon nanotube induction of rat aortic endothelial cell apoptosis: Reactive oxygen species are involved in the mitochondrial pathway.

The use of nano-sized materials offers exciting new options in technical and medical applications. Single-walled carbon nanotubes are emerging as technologically important in different industries. However, adverse effects on cells have been reported and this may limit their use. We previously found that 200µg/mL of single-walled carbon nanotubes induce apoptosis in rat aorta endothelial cells. The current study aimed to determine the signaling pathway involved in this process. We found that reactive oxygen species generation was involved in activation of the mitochondria-dependent apoptotic pathway. The finding of apoptosis was supported by a number of morphological and biochemical hallmarks, including chromatin condensation, internucleosomal DNA fragmentation, and caspase-3 activation. In conclusion, our results demonstrate that single-walled carbon nanotubes induce apoptosis in rat aorta endothelial cells and that reactive oxygen species are involved in the mitochondrial pathway.

[Linezolid versus vancomycin in the treatment of pneumonia caused by Gram-positive cocci: meta-analysis of randomised controlled trials].

OBJECTIVE: To study the randomised controlled trials on the efficacy and safety in patients with pneumonia caused by Gram-positive cocci treated with linezolid versus with vancomycin. METHODS: The data were collected from the MEDLINE database, EMBASE, OVID, the Cochrane library, and Chinese Biomedical Database, and the references of eligible studies were manually screened. Randomized controlled trials published in the English and Chinese literatures comparing linezolid with vancomycin in patients with pneumonia caused by Gram-positive cocci were eligible for inclusion. RESULTS: Seven randomized controlled studies comparing linezolid with vancomycin were analyzed, focusing on 1425 patients with pneumonia caused by Gram-positive cocci. It was found by meta-analysis that, with respect to clinical treatment success, linezolid was more effective than vancomycin in clinically evaluation patients at the end-of-treatment visit (OR=2.16, 95%CI 1.13-4.16, P<0.05), however, there was no difference in clinical treatment success for clinically evaluation patients (OR=1.11, 95%CI 0.81-1.53, P>0.05) and intention-to-treat patients (OR=1.01, 95%CI 0.78-1.31, P>0.05) at the test-of-cure visit. With respect to microbiological treatment success, linezolid was as effective as vancomycin in microbiologically evaluation patients at the test-of-cure visit (OR=1.31, 95%CI 0.85-2.04, P>0.05). Additionally, empirical treatment with linezolid was not associated with increased eradication rates for aureus strains (OR=1.45, 95%CI 0.84-2.51, P>0.05) and methicillin resistant Staphylococcus aureus strains (OR=1.36, 95%CI 0.51-3.61, P>0.05) in comparison with vancomycin in microbiologically evaluation patients at the test-of-cure visit, and, there was no difference in eradication rates for streptococcal species (OR=4.27, 95%CI 0.01-1365.87, P>0.05) and enterococcal species (OR=0.75, 95%CI 0.03-17.51, P>0.05).Mortality was similar between the groups (OR=0.80, 95%CI 0.59-1.07, P>0.05). Treatment with linezolid was not associated with more adverse effects in general in comparison with vancomycin (OR=1.06, 95%CI 0.68-1.64, P>0.05). CONCLUSIONS: Linezolid is at least as effective as vancomycin for treatment of patients with pneumonia caused by gram-positive cocci although rigorously designed large sample sized, randomized double blind clinical trials are required to further demonstrate and support the conclusion.