Browsing by Issue Date, starting with "2014-02-20"
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- Role of inter-species recombination of the ftsI gene in the dissemination of altered penicillin-binding-protein-3-mediated resistance in Haemophilus influenzae and Haemophilus haemolyticusPublication . Witherden, E.A.; Bajanca-Lavado, Maria Paula; Tristram, S.G.; Nunes, A.Objectives: To screen the ftsI gene sequences obtained from clinical isolates of non-typeable H. influenzae (NTHi), and Haemophilus haemolyticus for the presence of mosaic ftsI gene structures, and to evaluate the role homologous recombination of the ftsI gene has on the formation and distribution of resistant ftsI genes in NTHi. Methods: The ftsI genes of 100 Haemophilus isolates comprising genetically defined β-lactamase-negative ampicillin-susceptible (gBLNAS) and β-lactamase-negative ampicillin-resistant (gBLNAR) isolates of NTHi (n=50) and H. haemolyticus (n=50) were analyzed in this study. The full-length ftsI gene sequences of all study isolates were screened for mosaic ftsI gene structures using H. influenzae Rd and H. haemolyticus ATCC 33390 as reference parental sequences, and were subjected to recombination analysis using bioinformatics software Mega5 and Simplot. Results: Of the 100 clinical isolates analyzed 34% (34/100) harbored mosaic ftsI gene structures containing distinct ftsI gene fragments similar to both reference parental sequences. Inter-species recombination events were predominantly encountered in the ftsI gene of gBLNAR isolates of NTHi and H. haemolyticus, and were always associated with the formation of a mosaic fragment at the 3’ end of the ftsI gene. There was no evidence supporting the horizontal gene transfer (HGT) of the entire ftsI gene among the clinical isolates in vivo. Conclusion: We provide evidence for the HGT and inter-species recombination of the ftsI gene among isolates of NTHi and H. haemolyticus in a clinical setting, highlighting the importance recombination of the ftsI gene has on the emergence of altered PBP3s and BLNAR mediated resistance.
- Fungal contamination in two portuguese wastewater treatment plantsPublication . Viegas, C.; Faria, T.; Gomes, A.Q.; Sabino, R.; Seco, A.; Viegas, S.The presence of filamentous fungi was detected in wastewater and air collected at wastewater treatment plants (WWTP) from several European countries. The aim of the present study was to assess fungal contamination in two WWTP operating in Lisbon. In addition, particulate matter (PM) contamination data was analyzed. To apply conventional methods, air samples from the two plants were collected through impaction using an air sampler with a velocity air rate of 140 L/min. Surfaces samples were collected by swabbing the surfaces of the same indoor sites. All collected samples were incubated at 27◦C for 5 to 7 d. After lab processing and incubation of collected samples, quantitative and qualitative results were obtained with identification of the isolated fungal species. For molecular methods, air samples of 250 L were also collected using the impinger method at 300 L/min airflow rate. Samples were collected into 10 ml sterile phosphate-buffered saline with 0.05% Triton X-100, and the collection liquid was subsequently used for DNA extraction. Molecular identification of Aspergillus fumigatus and Stachybotrys chartarum was achieved by real-time polymerase chain reaction (RT-PCR) using the Rotor-Gene 6000 qPCR Detection System (Corbett). Assessment of PM was also conducted with portable direct-reading equipment (Lighthouse, model 3016 IAQ). Particles concentration measurement was performed at five different sizes: PM0.5, PM1, PM2.5, PM5, and PM10. Sixteen different fungal species were detected in indoor air in a total of 5400 isolates in both plants. Penicillium sp. was the most frequently isolated fungal genus (58.9%), followed by Aspergillus sp. (21.2%) and Acremonium sp. (8.2%), in the total underground area. In a partially underground plant, Penicillium sp. (39.5%) was also the most frequently isolated, also followed by Aspergillus sp. (38.7%) and Acremonium sp. (9.7%). Using RT-PCR, only A. fumigatus was detected in air samples collected, and only from partial underground plant. Stachybotrys chartarum was not detected in any of the samples analyzed. The distribution of particle sizes showed the same tendency in both plants; however, the partially underground plant presented higher levels of contamination, except for PM2.5. Fungal contamination assessment is crucial to evaluating the potential health risks to exposed workers in these settings. In order to achieve an evaluation of potential health risks to exposed workers, it is essential to combine conventional and molecular methods for fungal detection. Protective measures to minimize worker exposure to fungi need to be adopted since wastewater is the predominant internal fungal source in this setting.
- Assessment of fungal contamination in waste sorting and incineration-case study in PortugalPublication . Viegas, C.; Gomes, Q.; Abegão, J.; Sabino, R.; Graça, T.; Viegas, S.Organic waste is a rich substrate for microbial growth, and because of that, workers from waste industry are at higher risk of exposure to bioaerosols. This study aimed to assess fungal contamination in two plants handling solid waste management. Air samples from the two plants were collected through an impaction method. Surface samples were also collected by swabbing surfaces of the same indoor sites. All collected samples were incubated at 27◦C for 5 to 7 d. After lab processing and incubation of collected samples, quantitative and qualitative results were obtained with identification of the isolated fungal species. Air samples were also subjected to molecular methods by real-time polymerase chain reaction (RT PCR) using an impinger method to measure DNA of Aspergillus flavus complex and Stachybotrys chartarum. Assessment of particulate matter (PM) was also conducted with portable direct-reading equipment. Particles concentration measurement was performed at five different sizes (PM0.5; PM1; PM2.5; PM5; PM10). With respect to the waste sorting plant, three species more frequently isolated in air and surfaces were A. niger (73.9%; 66.1%), A. fumigatus (16%; 13.8%), and A. flavus (8.7%; 14.2%). In the incineration plant, the most prevalent species detected in air samples were Penicillium sp. (62.9%), A. fumigatus (18%), and A. flavus (6%), while the most frequently isolated in surface samples were Penicillium sp. (57.5%), A. fumigatus (22.3%) and A. niger (12.8%). Stachybotrys chartarum and other toxinogenic strains from A. flavus complex were not detected. The most common PM sizes obtained were the PM10 and PM5 (inhalable fraction). Since waste is the main internal fungal source in the analyzed settings, preventive and protective measures need to be maintained to avoid worker exposure to fungi and their metabolites.