Aspergillus fumigatus, an opportunistic fungal pathogen that causes invasive aspergillosis in immunosuppressed patients, is considered to be the world's most dangerous mould. It is widely distributed in the environment, and airborne asexual conidia serve as the main mode of transport for pulmonary lung infection. It is important to monitor seasonal airborne conidia levels when assessing the risk of acquiring this infection. In this study, air was sampled for total viable fungal spores and viable A. fumigatus conidia monthly over a 2-year period (2009 and 2010) close to Manchester, UK, city center. Total viable airborne fungal counts varied seasonally, peaking in the summer and autumn for both years and reaching levels of approximately 1100-1400 colony-forming units (CFU)/m(3); counts were strongly positively correlated to mean temperature (R(2) = 0.697). By contrast, A. fumigatus viable airborne counts were not seasonally associated; persistent low levels were between 3 and 20 CFU/m(3) and were not correlated with mean temperature (R(2) = 0.018). A total of 220 isolates of A. fumigatus were recovered on potato dextrose agar (PDA) at 45°C, and internal transcribed spacer sequencing and restriction digestion of a partial polymerase chain reaction amplicon of the β-tubulin gene (benA) of 34 randomly selected isolates were used to confirm the isolates as A. fumigatus. When the colony radial growth rates (Kr) were determined, the highest rates were observed on PDA, followed by Vogel's medium supplemented with phosphatidylcholine and Vogel's medium alone. Clinical isolates had a significantly higher mean colony Kr on PDA compared with environmental isolates.
Environmental populations of the opportunistic pathogen Aspergillus fumigatus have been shown to be genotypically diverse and to contain a range of isolates with varying pathogenic potential. In this study, we combined two RAPD primers to investigate the genetic diversity of environmental isolates from Manchester collected monthly over 1 year alongside Dublin environmental isolates and clinical isolates from patients. RAPD analysis revealed a diverse genotype, but with three major clinical isolate clusters. When the pathogenicity of clinical and Dublin isolates was compared with a random selection of Manchester isolates in a Galleria mellonella larvae model, as a group, clinical isolates were significantly more pathogenic than environmental isolates. Moreover, when relative pathogenicity of individual isolates was compared, clinical isolates were the most pathogenic, Dublin isolates were the least pathogenic and Manchester isolates showed a range in pathogenicity. Overall, this suggests that the environmental population is genetically diverse, displaying a range in pathogenicity, and that the most pathogenic strains from the environment are selected during patient infection. INTRODUCTIONAspergillus fumigatus is an opportunistic fungal pathogen that can cause aspergillosis in immunocompromised patients, such as those with neutropenia or on immunosuppressive therapy following solid organ transplantation (Abad et al., 2010;Ben-Ami et al., 2010;Dagenais & Keller, 2009;Latgé, 1999;Rementeria et al., 2005). The principal route of infection is through the inhalation of airborne spores, which due to their small spore size are able to reach the alveoli (Dagenais & Keller, 2009;Ibrahim-Granet et al., 2003;Latgé, 1999;O'Gorman, 2011;Philippe et al., 2003). While other aspergilli can cause opportunistic infections (such as Aspergillus terreus and Aspergillus flavus), A. fumigatus accounts for~90 % of all cases despite airborne spore numbers only accounting for ,1 % of all Aspergillus spores (Rementeria et al., 2005). A number of studies have shown a high degree of genetic variation within the A. fumigatus population, and whilst some studies have indicated potential geographical subgroups, comparisons between clinical isolates and environmental isolates have largely been unable to distinguish these populations (Araujo et al., 2010;Aufauvre-Brown et al., 1992;Balajee et al., 2008;Chazalet et al., 1998;Denning et al., 1990;Duarte-Escalante et al., 2009; Leenders et al., 1999;Menotti et al., 2005). Moreover, epidemiological studies have largely failed to match genotypes in infected patients with genotypes found in hospitals, in part due to the high level of genetic diversity in the environmental populations (Araujo et al., 2010;Bart-Delabesse et al., 1999;Chazalet et al., 1998;Guinea et al., 2011; Leenders et al., 1999;de Valk et al., 2007), and similar findings have been reported in avian populations (Arné et al., 2011;Lair-Fulleringer et al., 2003;Olias et al., 2011). Whilst genotyping of isolates from some individual patient...
Alpha-1 antitrypsin (AAT) is an acute phase protein produced in hepatocytes. Its deficiency affects the lungs and liver. A case–control study was carried out to determine the prevalence of 2 common deficiency alleles, PI∗S and PI∗Z, for alpha-1 antitrypsin deficiency (AATD) in both healthy and chronic obstructive pulmmonary disease (COPD)-affected Saudi populations and to clarify the importance of genetic tests in the screening of people at risk for COPD.One thousand blood samples from healthy individuals and 1000 from COPD-affected Saudi individuals were genotyped for the above-mentioned alleles, using real-time polymerase chain reaction (PCR), with the exclusion of any other nationalities. Data were analyzed by determining the allele and genotype frequencies through gene counting and its confidence intervals. The allele frequencies, derived by the Hardy–Weinberg equilibrium method, were analyzed by Pearson Chi-squared tests. The confidence intervals for genotype frequencies were calculated using exploratory software for confidence intervals.Of the 1000 COPD patients included in our study, the prevalence of PI∗S and PI∗Z was 21.8% and 7.7%, respectively, while within the 1000 normal samples, these alleles occurred in 8.9% of patients for PI∗S and 1.6% for PI∗Z. The AAT deficiency genotype frequencies (PI∗ZZ, PI∗SS, and PI∗SZ) were 6.5 per 1000 and 87 per 1000 for normal and COPD-affected Saudi individuals.Our results indicated a high prevalence of AATD alleles in the normal Saudi population and an association between AAT deficiency and pulmonary disease development. Additionally, our research confirms the importance of genetic screening to achieve early and accurate diagnosis of AATD.
Industrial antimicrobials have been extensively used to control unwanted microbial growth by incorporation into a variety of products such as plastics and paints, reducing biodeterioration and biofouling and extending the lifespan of the product. Industrial antimicrobials generally have broad sites of action affecting core cellular functions such as central metabolism, enzyme function, cell wall or DNA synthesis and can either be biocidal or biostatic. In addition, susceptibility can be affected by the metabolic state of the microbe, with metabolically inactive cells generally more resistant than metabolically active cells. Previously it was demonstrated that cytosolically expressed green fluorescent protein could be used as a real-time viability indicator in the yeast Aureobasidium pullulans based on the pH dependent fluorescence of GFP and the collapse of the proton gradient across the cell membrane during cell death. In this study we report on the development and validation of an equivalent GFP fluorescence viability assay in Escherichia coli and used this assay to study the effect of five antimicrobials commonly used in plastics; 4,5-dichloro-2-octyl-isothiazol-3-one (DCOIT), sodium pyrithione, 1,2-benzisothiazol-3-one (BIT), 2-octyl-isothiazol-3-one (OIT) and n-butyl-1,2-benzisothiazol-3-one (BBIT). The results demonstrate broad differences amongst the antimicrobials in both relative efficacy, rate of effect and for some antimicrobials, marked differences in sensitivity toward growing and non-growing cells.
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