Browsing by Author "Carvalho, Patricia ALmeida"
Now showing 1 - 2 of 2
Results Per Page
Sort Options
- Bacterial biofilms: a story of persistence and invasionPublication . Sousa, Sara; Bandeira, Maria; Carvalho, Patricia ALmeida; Duarte, Aida; Jordão, LuísaBiofilms are described as colonies of microorganisms that are attached to each other and to a surface, in an irreversible mode. These structures are virtualy everywhere: natural and humanized environments, as well as within living beings (humans and animals). For a long time biofilms where regarded as a bacterial survival strategie. Nowadays, in the industrialized world, the impact of acute bacterial infections caused by rapidly proliferating planktonic cells have gradually decreased in comparison to chronic infections owing to environmental organisms growing as biofilms. The major concern in this field is the healthcare-associated infections (HAIs). In 2012, HAIs estimated cases reached 6.7 million either in long-term care facilities or acute-care hospitals from which result 37,000 deaths configuring a serious public health problem [1]. The etiological agents are diverse being often resistant to antimicrobials and able to assemble biofilms both in abiotic and biotic surfaces. Here we evaluated the ability of different bacteria to assemble biofilms on a model surface and materials mimicking surfaces present either on healthcare units or medical devices. All bacteria were able to assemble biofilmls although following different kinetics and exhibiting different structural features assessed by electron microscopy. Additionally a link was established between bacteria ability to assemble biofilms and increased antibiotic resistance [2]. 1. ECDC Europe; (2012), Annual epidemiological report 2011 2. Bandeira M; (2014), Pathogens (doi:10.3390/pathogens3030720)
- Using new scanning electron microscopy (SEM) approaches to elucidate bacterial biofilm architecturePublication . Bandeira, Maria; Duarte, Aida; Carvalho, Patricia ALmeida; Jordão, LuisaHealthcare-associated infections (HAI) are a major public health problem being Klebsiella pneumoniae and nontuberculous mycobacteria, both with high antibiotic resistance rates, among their etiological agent. Since biofilme assembly is pointed as one of the mechanisms involved in emergence of antibiotic resistance understanding bacteria organization within the biofilm and the identification of differences between planktonic and sessile forms of bacteria will be a step forward to fight HAI. In the present work we used SEM as a tool to characterize the internal structure of biofilm assembled on different surfaces. For SEM analysis, biofilms were allowed to form either on six-well cell culture plates, silicon or metallic disks placed inside the wells for different incubation periods at 37 °C. The biofilm assembled on the cell culture dish was for both secondary and backscattered electron analysis as described before. Biofilms assembled on silicon disks instead of being sectioned were prepared as metallographic samples, by grinding with grit SIC paper and polishing with diamond particles. Samples were cleaned (70% ethanol), dried with hot air, further coated and analysed. A preliminary study using FIB-SEM has been performed to access the ultrastructure of biofilms assembled on metallic surfaces. The results obtained showed that the same bacteria assembled biofilms with different ratios of biomass and extracellular matrix depending on the surface. SEM performed on thin sections of biofilms is a powerful tool to elucidate biofilm structure allowing the quantification of the major components. FIB-SEM is also a promising tool in this field.