QuEChER method for air microbiological monitoring in hospital environments.

INTRODUCTION: Nosocomial pathogens have become a priority issue for public health, since they are responsible for increased morbidity and mortality in hospitalized patients and the development of multi-resistant microorganisms, as well. Recent studies found strong evidence that airborne transmission plays a key role in many nosocomial infections. Thus, we aim to develop a QuEChER methodology for the characterization of airborne microbial levels, analyzing potential variables that modify the air microbiological load. METHODOLOGY: Particulate matter levels and suspended and settled bioaerosols were determined simultaneously employing optical sensors, Harvard impactors and settle plates, respectively. Environmental variables were also measured at different sites during different working shifts and seasons. RESULTS: We found a straightforward relationship between airborne particles, air exchange rates, and people influx. Levels of suspended microorganisms were related to fine particulate matter concentration, CO2 and ambient temperature. A positive linear relationship (R2 = 0.9356) was also found between fine particulate matter and CO2 levels and air microbial load. CONCLUSION: The QuEChER methodology is an effective methodology that could be used to improve the surveillance of nosocomial pathogens in developing countries hospitals where air quality is scarcely controlled.

Composition and mutagenicity of PAHs associated with urban airborne particles in Córdoba, Argentina.

The comet assay and micronucleous test were used to assess the genotoxicity of organic compounds associated with particulate material collected in the city of Córdoba, Argentina. Samples were collected on fiber glass filters and their organic extracts were analyzed by GC-MS. These extracts were used for the comet assay on human lymphocytes and for the MCN test with Tradescantia pallida. The concentrations of polycyclic aromatic hydrocarbons as well as some of their nitro derivates were higher during winter. Their composition suggested that their main emission sources were gasoline and diesel vehicles. We observed genotoxic effects of these organic extracts due to the presence of both direct and indirect acting mutagens. We found a good agreement between the two test systems employed, which encourages the further use of plant bioassays for air pollution monitoring, especially in developing countries, due to their flexibility, low cost and efficiency.

The effect of airborne particles and weather conditions on pediatric respiratory infections in Cordoba, Argentine.

We studied the effect of estimated PM(10) on respiratory infections in children from Cordoba, Argentine as well as the influence of weather factors, socio-economic conditions and education. We analyzed upper and lower respiratory infections and applied a time-series analysis with a quasi-Poisson distribution link function. To control for seasonally varying factors we fitted cubic smoothing splines of date. We also examined community-specific parameters and differences in susceptibility by sex. We found a significant association between particles and respiratory infections. This relationship was affected by mean temperature, atmospheric pressure and wind speed. These effects were stronger in fall, winter and spring for upper respiratory infections while for lower respiratory infections the association was significant only during spring. Low socio-economic conditions and low education levels increased the risk of respiratory infections. These findings add useful information to understand the influence of airborne particles on children health in developing countries.

Assessment of human health risk related to metals by the use of biomonitors in the province of Córdoba, Argentina.

The evaluation of metal contents in the environment is of vital importance for the assessment of human exposure. Thus the species Usnea amblyoclada, Ramalina celastri and Tillandsia capillaris were tested as bioaccumulators of transition metals in the urban area of Córdoba city, Argentina. The level of metals on biomonitors was compared to that of total deposition samples. All three species discriminated zones within the urban area of Córdoba city with different pollution levels; they revealed high levels of Zn in the downtown area and confirmed high levels of some transition metals in an industrial area. The correlation analysis revealed that the lichen R. celastri had the highest correlation rates with total deposition samples, suggesting it is a valuable biomonitor of atmospheric pollution. A significant relationship was also observed between respiratory diseases in children and the contents of metal accumulated in R. celastri and T. capillaris, indicating their usefulness when assessing human exposure to metals.

Estudio de la relación entre los niveles de deposición atmosférica total y algunos indicadores de salud respiratoria en la ciudad de Córdoba / Relationship between atmospheric deposition levels and some respiratory health indicators in the city of Córdoba

Antecedentes: si bien existe numerosa información sobre los efectos de material particulado en la salud humano, son muy escasos los estudios realizados en países en desarrollo, donde las condiciones socioeconómicas así como el tipo y niveles de contaminantes son muy diferentes de los países desarrollados. Objetivo. Evaluar la relación entre los niveles de deposición atmosférica total (húmeda y seca), los cuales estuvieron expuestos durante 6 meses. El número total de pacientes que fueron atendidos por afecciones respiratorias en los centros de salud localizados cerca de los puntos de muestreo se obtuvo de las bases de datos de la Municipalidad de Córdoba. Con todas las afecciones respiratorias estudiadas, se creó una nueva variable a partir de la suma de sus registros y se calculó su frecuencia. Ésta fue luego relacionada con los valores de deposición total correspondientes a cada sitio de muestreo. Resultados y conclusiones. Se observó una relación significativa entre ambas variables, lo cual sugiere que esta metodología sencilla y de bajo costo podría ser de utilidad para estimar el riesgo de exposición del hombre a material particulado atmosférico.

Effects of the heavy metals Cu2+, Ni2+, Pb2+, and Zn2+ on some physiological parameters of the lichen Usnea amblyoclada.

The effect of Cu2+, Ni2+, Pb2+, and Zn2+ on some physiological parameters of the lichen Usnea amblyoclada and the selective uptake of Cu2+ and Pb2+ was assessed. Fresh thalli were soaked in single or mixed metallic solutions. The concentration of chlorophylls and malondialdehyde; the dry weight/fresh weight ratio as well as the water content and the concentration of Cu, Ni, Pb, and Zn were measured in the treated and control thalli. The exposure to Cu, Ni, and Pb solutions caused several changes on the parameters measured; no differences were found with Zn. A stronger ability for binding Pb2+ was also observed. The results suggest that Cu2+ was the most harmful cation followed by Pb and Ni. Consequently, the damage observed in U. amblyoclada thalli when it is used as a biomonitor in polluted areas is possibly due to the presence of these heavy metals, masking the effect of other gaseous pollutants.

Assessment of heavy metal accumulation in two species of Tillandsia in relation to atmospheric emission sources in Argentina.

The ability of Tillandsia capillaris Ruiz and Pav. f. capillaris and Tillandsia permutata A. Cast. to accumulate heavy metals was evaluated in relation to potential atmospheric emission sources in Argentina. The sampling areas (n=38) were chosen in the province of Córdoba, located in the center of Argentina, and categorized according to land use, anthropogenic activities and/or distance to potential heavy metal emission sources. In each sampling site, pools of 40-50 individuals of each species were made from plants collected along the four cardinal directions. The concentrations of V, Mn, Fe, Co, Ni, Cu, Zn, Pb and Br of these samples were measured by Total Reflection X-Ray Fluorescence (TXRF) analysis with Synchrotron Radiation. Each species was submitted to a cluster analysis in order to discriminate different groups of heavy metals as tracers of natural or anthropogenic sources. A Contamination Factor (CF) was calculated using the concentrations of the elements in each sample compared to their concentrations in the control samples. Finally, the rank coefficients of correlation between the CFs and the categorical variables characteristic of each site (land use and anthropogenic load) were analyzed. A positive correlation was found for T. capillaris between the CFs of V, Mn, Co, Ni, Cu and Zn and the urban-industrial category, whereas the CF values for Zn and Pb were positively correlated with the road category. In T. permutata there was a positive correlation between the CF of Zn and the urban-industrial category and the CF of Pb with the road category. We therefore conclude that T. capillaris is a more efficient metal accumulator in passive biomonitoring studies.

The role of urban air pollutants on the performance of heavy metal accumulation in Usnea amblyoclada.

Lichens incorporate heavy metals according to a selectivity sequence; therefore, their uptake rate can be affected when elements with a high affinity for cell wall exchange sites or that provoke harmful alterations to the metabolism of lichen thalli are present in the environment. The aim of this study was to examine the effect of urban pollutants on the accumulation of some heavy metals in Usnea amblyoclada. Lichen samples were transplanted for 1 month to both a polluted and a nonpolluted area in Cordoba, Argentina. They were then collected and soaked in tridistilled water or in solutions containing different concentrations of Cu, Ni, Pb, and Zn salts. The uptake of Cu2+, Ni2+, Zn2+, and Pb2+, and other parameters indicative of lichen damage were measured in all the lichen samples. The thalli retrieved from the polluted area showed significant increases in both the malonaldehyde content and the electrical conductivity of the water in which they had been immersed. These results indicate that the atmospheric pollutants could be responsible for the significant damage to the lichen's cellular membranes, thus altering several mechanisms related to the uptake of heavy metals. Both the area of transplantation and the concentration of the metallic solutions had significant effects on the levels of Cu, Ni, and Pb measured in lichen thalli; however, no significant differences were observed in Zn concentrations. The highest uptakes corresponded to Pb and Cu, suggesting that they probably have a higher affinity with the lichen cell wall exchange sites. This study confirms the fact that, although lichens can be useful biological indicators, the physiological mechanisms involved in metal uptake should be carefully analyzed. Therefore, when estimating the heavy metal content of an environment, the competitive mechanism for cation uptake should be considered especially in areas where the presence of high levels of metals with a strong binding affinity is suspected. The presence of secondary products in the lichens could be responsible for the selective uptake of cations and for a possible tolerance to their presence.

Biomonitoring of heavy metals and air quality in Cordoba City, Argentina, using transplanted lichens.

The objective of the present study was to test the concentrations of some elements in the transplanted lichen Usnea amblyoclada transplanted in Córdoba, Argentina, and to investigate the relative air quality of the area as indicated by a Pollution Index. Analyses of Cu, Co. Pb, Fe, Ni, Mn, S and Zn in addition to analyses of physiological parameters were performed after the transplantation period. No significant differences were observed among the sampling stations for the physiological parameters, except the dry weight/fresh weight ratio. The concentration of most elements was similar to or lower than those found in non-polluted and even polluted areas. The significant correlation found between Cu, Pb and Zn with the content of hydroperoxy conjugated dienes suggests an important oxidative effect probably caused by these ions. The distribution patterns of the elements were quite similar, with maximum values around a cement plant and the metallurgical industries. The Pollution Index distribution pattern does not coincide with the elements distribution, due to the fact that the index values probably reflected the emissions of gaseous phytotoxic pollutants.