Rhinovirus-associated wheezing and asthma in young children

Human rhinoviruses (HRV) are a common cause of the common cold, and are thought to be associated with asthma exacerbations in both children and adults. Recently, HRV have been identified as a major cause of hospitalization in children \u3c 5 years old. The purpose of this study was too determine whether HRV are a cause of either wheezing and/or hospitalization in children \u3c 2 years old. We used a PCR assay to screen for HRV infection in children \u3c 2 years old: 1) with symptoms of upper or lower respiratory tract disease without wheezing; 2) with wheezing; 3) who were asymptomatic. A group of children who had a respiratory specimen submitted to a diagnostic laboratory for whatever reason and who tested negative for four common viruses in the clinical lab were also screened. All specimens were collected between January 1 and December 31, 2004. Phylogenetic analyses were performed on a majority of HRV isolates. Overall, 28 (17%) of 165 children with symptoms of respiratory traction infection without wheezing; 21 (26.3%) of 80 children with symptoms of respiratory tract infection and wheezing; 3 (3%) of 93 asymptomatic children and 47 (23.3%) of 202 children with specimens submitted to the diagnostic laboratory tested positive for HRV. The difference between the rate of infection in the asymptomatic group and each of the three other groups was statistically significant (p\u3c0.01). Among children with samples submitted to the diagnostic laboratory in whom HRV was the only identified pathogen, 55% were hospitalized. This rate was similar to that observed for respiratory syncytial virus (52.7%) among children of a similar age group and time period (P=0.85). Diverse groups of HRV were circulating during the one-year study period. We conclude that HRV are important pathogens among young children \u3c 2 years old and are responsible for a significant proportion of wheezing this age group. Among a group of children with a respiratory specimen submitted to the diagnostic laboratory in whom a rhinovirus was the only identified pathogen, a majority were hospitalized

Structure of microbial community in soils contaminated with heavy metals assessed by culture and fatty acid approaches

Badano wpływ Cu, Zn i Cd na liczebność, biomasę oraz strukturę ogólnej i zdolnej do wzrostu na podłożach hodowlanych populacji bakterii w warunkach laboratoryjnych. Glebę skażono Cu lub Zn w dawce 1000 lub 2000 pg g oraz Cd w dawce 500 lub 1000 pg g' gleby. Po 15, 60 i 90 dniach od skażenia gleby określono w niej zawartość wymywalnych wodą jonów wprowadzonych metali, ogólną liczebność bakterii na podłożu TSA oraz biomasę bakterii i grzybów na podstawie zawartości wybranych fosfolipidowych kwasów tłuszczowych (PLFA). Strukturę zdolnej do wzrostu frakcji bakterii określano na podstawie profili komórkowych kwasów tłuszczowych (FAMĘ) oraz na podstawie koncepcji r- i K-strategów. Do oceny bioróżnorodności populacji bakterii zastosowano współczynnik ekofizjologiczny (EP) i rozwoju kolonii (CD). Strukturę całego zespołu bakterii glebowych oceniano, opierając się na profilach PLFA izolowanych bezpośrednio z gleby. Zawartość wymywalnych wodą jonów Cu, Zn i Cd stanowiła jedynie kilka procent wprowadzonych do gleby metali i zmniejszała się w czasie trwania doświadczenia. Wykazano, że metale ciężkie mają jedynie krótkotrwały negatywny wpływ na ogólną liczebność bakterii. Po 60 dniach inkubacji nie stwierdzono istotnych różnic pomiędzy liczebnością mikroorganizmów w glebach skażonych a kontroli. Obserwowano natomiast istotny wpływ wprowadzonych metali na biomasę mikroorganizmów. W glebach skażonych wyższymi dawkami metali biomasa bakterii była zawsze niższa w porównaniu z biomasą bakterii w glebie kontrolnej. Wartości parametrów EP i CD wskazują na wyraźne zmiany w strukturze zespołów bakterii zdolnych do wzrostu w glebach skażonych Cu, Zn i Cd. Wszystkie metale powodowały przebudowę struktury zespołów bakterii w kierunku dominacji K-strategów. Największą redukcję bioróżnorodności stwierdzono w glebach skażonych Zn i Cd, w których wartość parametru EP (od 0,518 do 0,553) była istotnie niższa od wartości EP w kontroli (0,707). Profil komórkowych kwasów tłuszczowych (FAMĘ) izolowanych z wyrosłych komórek wskazuje na dominację bakterii Gram-dodatnich zarówno w glebie kontrolnej, jak i skażonej metalami. Nie zaobserwowano istotnych zmian w profilach FAME badanych zespołów, jakkolwiek procentowy udział rozgałęzionych kwasów tłuszczowych w glebach zanieczyszczonych Cu, Zn i Cd był wyższy niż w glebie kontrolnej. Zespoły wyrosłych na podłożu TSA bakterii były mniej zróżnicowane w porównaniu z zespołami mikroorganizmów określanymi za pomocą fosfolipidowych kwasów tłuszczowych, izolowanych bezpośrednio z gleby. Analiza profili tych kwasów wskazuje na wyraźne zmiany w obrębie struktury badanych zespołów bakterii w glebach potraktowanych różnymi metalami i kontrolą. Zmiany w profilu PLFA zależały od rodzaju metalu, jego dawki i czasu, w którym pobierano próbki. Po 90 dniach inkubacji w glebach skażonych Cu, Zn i Cd stwierdzono spadek zawartości rozgałęzionych kwasów tłuszczowych i 14:0 i i 15:0 oraz wzrost ilości kwasów i 17:0 i a 17:0 w stosunku do kontroli. W glebach skażonych metalami wzrosła również ilość kwasu 16:ko7t, natomiast zawartość innych kwasów nienasyconych, jak i kwasów cyklopropanowych zmieniała się w zależności od rodzaju metalu wprowadzonego do gleby. Analiza dendrogramów, utworzonych na podstawie uzyskanych profili PLFA, obrazujących podobieństwa między zespołami bakterii w badanych glebach, wskazuje, że mikroorganizmy w różny sposób reagują na skażenie gleby Cu, Zn i Cd

Molecular basis of active cooper resistance mechanisms in Gram-negative bacteria

Copper is a metallic element that is crucial for cell metabolism; however, in extended concentrations, it is toxic for all living organisms. The dual nature of copper has forced organisms, including bacteria, to keep a tight hold on cellular copper content. This challenge has led to the evolution of complex mechanisms that on one hand enable them to deliver the essential element and on the other to protect cells against its toxicity. Such mechanisms have been found in both eukaryotic and prokaryotic cells. In bacteria a number of different systems such as extra- and intracellular sequestration, enzymatic detoxification, and metal removal from the cell enabling them to survive in the presence of high concentration of copper have been identified. Gram-negative bacteria, due to their additional compartment, need to deal with both cytoplasmic and periplasmic copper. Therefore, these bacteria have evolved intricate and precisely regulated systems which interact with each other. In this review the active mechanisms of copper resistance at their molecular level are discussed

Community structure of ammonia-oxidizing archaea (AOA) and ammonia-oxidizing bacteria (AOB) in soil treated with the insecticide imidacloprid

The purpose of this experiment was to assess the effect of imidacloprid on the community structure of ammonia-oxidizing archaea (AOA) and ammonia-oxidizing bacteria (AOB) in soil using the denaturing gradient gel electrophoresis (DGGE) approach. Analysis showed that AOA and AOB community members were affected by the insecticide treatment. However, the calculation of the richness (S) and the Shannon-Wiener index (H) values for soil treated with the field rate (FR) dosage of imidacloprid (1 mg/kg soil) showed no changes in measured indices for the AOA and AOB community members. In turn, the 10× FR dosage of insecticide (10 mg/kg soil) negatively affected the AOA community, which was confirmed by the decrease of the S and H values in comparison with the values obtained for the control soil. In the case of AOB community, an initial decline followed by the increase of the S and H values was obtained. Imidacloprid decreased the nitrification rate while the ammonification process was stimulated by the addition of imidacloprid. Changes in the community structure of AOA and AOB could be due to an increase in the concentration of N-NH4 +, known as the most important factor which determines the contribution of these microorganisms to soil nitrification

Pyrethroid-Degrading Microorganisms and Their Potential for the Bioremediation of Contaminated Soils: A Review

Pyrethroid insecticides have been used to control pests in agriculture, forestry, horticulture, public health and for indoor home use for more than 20 years. Because pyrethroids were considered to be a safer alternative to organophosphate pesticides (OPs), their applications significantly increased when the use of OPs was banned or limited. Although, pyrethroids have agricultural benefits, their widespread and continuous use is a major problem as they pollute the terrestrial and aquatic environments and affect non-target organisms. Since pyrethroids are not degraded immediately after application and because their residues are detected in soils, there is an urgent need to remediate pyrethroid-polluted environments. Various remediation technologies have been developed for this purpose; however, bioremediation, which involves bioaugmentation and/or biostimulation and is a cost-effective and eco-friendly approach, has emerged as the most advantageous method for cleaning-up pesticide-contaminated soils. This review presents an overview of the microorganisms that have been isolated from pyrethroid-polluted sites, characterized and applied for the degradation of pyrethroids in liquid and soil media. The paper is focused on the microbial degradation of the pyrethroids that have been most commonly used for many years such as allethrin, bifenthrin, cyfluthrin, cyhalothrin, cypermethrin, deltamethrin, fenpropathrin, fenvalerate, and permethrin. Special attention is given to the bacterial strains from the genera Achromobacter, Acidomonas, Bacillus, Brevibacterium, Catellibacterium, Clostridium, Lysinibacillus, Micrococcus, Ochrobactrum, Pseudomonas, Serratia, Sphingobium, Streptomyces, and the fungal strains from the genera Aspergillus, Candida, Cladosporium, and Trichoderma, which are characterized by their ability to degrade various pyrethroids. Moreover, the current knowledge on the degradation pathways of pyrethroids, the enzymes that are involved in the cleavage of pesticide molecules, the factors/conditions that influence the survival of strains that are introduced into soil and the rate of the removal of pyrethroids are also discussed. This knowledge may be useful to optimize the environmental conditions of bioremediation and may be crucial for the effective removal of pyrethroids from polluted soils

Use of the PCR-DGGE method for the analysis of the bacterial community structure in soil treated with the cephalosporin antibiotic cefuroxime and/or inoculated with a multidrug-resistant Pseudomonas putida strain MC1

The widespread use of cefuroxime (XM) has resulted in the increase in its concentration in hospital and domestic wastewaters. Due to the limited removal of antibiotics and antibiotic-resistant genes in conventional systems, the drugs enter the surface water and soils. Moreover, the introduction of XM and/or XM-resistant bacteria into soil may cause a significant modification of the biodiversity of soil bacterial communities. Therefore, the goal of this research was to assess the genetic diversity of a bacterial community in the cefuroxime (XM1-1 mg/kg and XM10-10 mg/kg) and/or antibiotic-resistant Pseudomonas putida strain MC1 (Ps - 1.6 × 107 cells/g)-treated soils as determined by the DGGE (denaturing gradient gel electrophoresis) method. The obtained data were also evaluated using a multivariate analysis and the resistance (RS)/resilience (RL) concept. Strain MC1 was isolated from raw sewage in the presence of XM and was resistant not only to this antibiotic but also to vancomycin, clindamycin and erythromycin. The DGGE patterns revealed that the XM10 and XM10+Ps treatments modified the composition of the bacterial community by the alteration of the DGGE profiles as well as a decline in the DGGE indices, in particular on days 30, 60, and 90. In turn, the XM1 and XM1+Ps or Ps treatments did not affect the values of richness and diversity of the soil bacteria members. A principal component analysis (PCA) also indicated that XM markedly changed the diversity of bacterial assemblages in the second part of the experiment. Moreover, there were differences in the RS/RL of the DGGE indices to the disturbances caused by XM and/or Ps. Considering the mean values of the RS index, the resistance was categorized in the following order: diversity (0.997) > evenness (0.993) > richness (0.970). The soil RL index was found to be negative, thus reflecting the progressing detrimental impact of XM on the genetic biodiversity of bacteria within the experiment. These results indicate that the introduction of XM at higher dosages into the soil environment may exert a potential risk for functioning of microorganis

Antibiotics in the Soil Environment - Degradation and Their Impact on Microbial Activity and Diversity

Antibiotics play a key role in the management of infectious diseases in humans, animals, livestock, and aquacultures all over the world. The release of increasing amount of antibiotics into waters and soils creates a potential threat to all microorganisms in these environments. This review addresses issues related to the fate and degradation of antibiotics in soils and the impact of antibiotics on the structural, genetic and functional diversity of microbial communities. Due to the emergence of bacterial resistance to antibiotics, which is considered a worldwide public health problem, the abundance and diversity of antibiotic resistance genes (ARGs) in soils are also discussed. When antibiotic residues enter the soil, the main processes determining their persistence are sorption to organic particles and degradation/transformation. The wide range of DT50 values for antibiotic residues in soils shows that the processes governing persistence depend on a number of different factors, e.g., physico-chemical properties of the residue, characteristics of the soil, and climatic factors (temperature, rainfall, and humidity). The results presented in this review show that antibiotics affect soil microorganisms by changing their enzyme activity and ability to metabolize different carbon sources, as well as by altering the overall microbial biomass and the relative abundance of different groups (i.e., Gram-negative bacteria, Gram-positive bacteria, and fungi) in microbial communities. Studies using methods based on analyses of nucleic acids prove that antibiotics alter the biodiversity ofmicrobial communities and the presence ofmany types of ARGs in soil are affected by agricultural and human activities. It is worth emphasizing that studies on ARGs in soil have resulted in the discovery of new genes and enzymes responsible for bacterial resistance to antibiotics. However, many ambiguous results indicate that precise estimation of the impact of antibiotics on the activity and diversity of soil microbial communities is a great challenge

Whole cell-derived fatty acid profiles of Pseudomonas sp. JS150 during naphthalene degradation

Changes in cellular fatty acid composition during naphthalene degradation, at the concentrations of 0.5 g lñ1 or 1.0 g lñ1,by Pseudomonas sp. JS150 were investigated. In response to naphthalene exposure an increase in saturated/unsaturatedratio was observed. Additionally, the dynamic changes involved alterations in the contents of hydroxy, cyclopropaneand branched fatty acids. Among the classes of fatty acids tested the most noticeable changes in the abundance ofcyclopropane fatty acids were observed. Since day 4 of incubation these fatty acids were not dectected in bacterial cellsgrowing on naphthalene. In contrast, markedly increased in the percentage of hydroxy fatty acids over time wasobserved. However, the proportions of saturated straight-chain and branched fatty acids did not change such significantly

Non-target impact of fungicide tetraconazole on microbial communities in soils with different agricultural management

Effect of the fungicide tetraconazole on microbial community in silt loam soils from orchard with long history of triazole application and from grassland with no known history of fungicide usage was investigated. Triazole tetraconazole that had never been used on these soils before was applied at the field rate and at tenfold the FR. Response of microbial communities to tetraconazole was investigated during 28-day laboratory experiment by determination of changes in their biomass and structure (phospholipid fatty acids method—PLFA), activity (fluorescein diacetate hydrolysis—FDA) as well as changes in genetic (DGGE) and functional (Biolog) diversity. Obtained results indicated that the response of soil microorganisms to tetraconazole depended on the management of the soils. DGGE patterns revealed that both dosages of fungicide affected the structure of bacterial community and the impact on genetic diversity and richness was more prominent in orchard soil. Values of stress indices—the saturated/monounsaturated PLFAs ratio and the cyclo/monounsaturated precursors ratio, were almost twice as high and the Gram-negative/Gram-positive ratio was significantly lower in the orchard soil compared with the grassland soil. Results of principal component analysis of PLFA and Biolog profiles revealed significant impact of tetraconazole in orchard soil on day 28, whereas changes in these profiles obtained for grassland soil were insignificant or transient. Obtained results indicated that orchards soil seems to be more vulnerable to tetraconazole application compared to grassland soil. History of pesticide application and agricultural management should be taken into account in assessing of environmental impact of studied pesticides