RESUMO
In aquatic ecosystems, microplastics are a relatively new anthropogenic substrate that can readily be colonized by biofilm-forming organisms. To examine the effects of substrate type on microbial community assembly, we exposed ambient Baltic bacterioplankton to plastic substrates commonly found in marine environments (polyethylene, polypropylene and polystyrene) as well as native (cellulose) and inert (glass beads) particles for 2 weeks under controlled conditions. The source microbial communities and those of the biofilms were analyzed by Illumina sequencing of the 16S rRNA gene libraries. All biofilm communities displayed lower diversity and evenness compared with the source community, suggesting substrate-driven selection. Moreover, the plastics-associated communities were distinctly different from those on the non-plastic substrates. Whereas plastics hosted greater than twofold higher abundance of Burkholderiales, the non-plastic substrates had a significantly higher proportion of Actinobacteria and Cytophagia. Variation in the community structure, but not the cell abundance, across the treatments was strongly linked to the substrate hydrophobicity. Thus, microplastics host distinct bacterial communities, at least during early successional stages.
Assuntos
Bactérias/isolamento & purificação , Plásticos , Actinobacteria/isolamento & purificação , Bactérias/genética , Bacteroidetes/isolamento & purificação , Biofilmes , Burkholderiales/isolamento & purificação , Interações Hidrofóbicas e Hidrofílicas , Microbiota , Plâncton/genética , Plâncton/isolamento & purificação , RNA Ribossômico 16S/genéticaRESUMO
Staphylococcus epidermidis, a human commensal, is an important opportunistic, biofilm-forming pathogen and the main cause of late onset sepsis in preterm infants, worldwide. In this study we describe the characteristics of S. epidermidis strains causing late onset (>72 h) bloodstream infection in preterm infants and skin isolates from healthy newborns. Attachment and biofilm formation capability were analyzed in microtiter plates and with transmission electron microscopy (TEM). Clonal relationship among strains was studied with pulsed-field gel electrophoresis. Antimicrobial susceptibility testing was performed, as well as the detection of biofilm-associated genes and of the invasiveness marker IS256 with polymerase chain reaction. Blood and skin isolates had similar attachment and biofilm-forming capabilities and biofilm formation was not related to the presence of specific genes. Filament-like membrane structures were seen by TEM early in the attachment close to the device surface, both in blood and skin strains. Nine of the ten blood isolates contained the IS256 and were also resistant to methicillin and gentamicin in contrast to skin strains. S. epidermidis strains causing bloodstream infection in preterm infants exhibit higher antibiotic resistance and are provided with an invasive genetic equipment compared to skin commensal strains. Adhesion capability to a device surface seems to involve bacterial membrane filaments.
Assuntos
Biofilmes/crescimento & desenvolvimento , Portador Sadio/microbiologia , Sepse/microbiologia , Infecções Estafilocócicas/microbiologia , Staphylococcus epidermidis/fisiologia , Técnicas Bacteriológicas , Elementos de DNA Transponíveis , Farmacorresistência Bacteriana , Eletroforese em Gel de Campo Pulsado , Humanos , Recém-Nascido Prematuro , Testes de Sensibilidade Microbiana , Microscopia Eletrônica de Transmissão , Tipagem Molecular , Reação em Cadeia da Polimerase , Staphylococcus epidermidis/classificação , Staphylococcus epidermidis/efeitos dos fármacos , Staphylococcus epidermidis/isolamento & purificação , Fatores de Virulência/genéticaRESUMO
Coagulase-negative staphylococci and its subtype Staphylococcus epidermidis are major indigenous Gram-positive inhabitants of the human skin. Colonization occurs in direct connection with birth and terrestrial adaptation. This study focuses on factors that may influence skin colonization of the newborn infant that relates to the immune status of both the bacteria and the host. Skin is an effective barrier against bacteria, and this function is partly mediated by the presence of antimicrobial peptides including human cathelicidin peptide LL37. Gram-positive bacteria have been described to have adhesive pili on their surface that mediates specific attachment to the host. Here, we identify, by negative staining transmission electron microscopy (EM), two different types of pilus-like structures commonly expressed on S. epidermidis isolated from newborn infants. We also show that the cathelicidin antimicrobial peptide LL37, constitutively expressed in the skin barrier of the newborn, significantly inhibited growth of S. epidermidis indicating its importance for the ecological stability of the skin microbiota. Further studies are required to elucidate molecular mechanisms of host-microbe interactions, both for the maintenance of a mutually beneficial homeostatic relationship and for the protection of self when it results in overt disease.
Assuntos
Antibacterianos/metabolismo , Peptídeos Catiônicos Antimicrobianos/metabolismo , Fímbrias Bacterianas/metabolismo , Staphylococcus epidermidis/citologia , Staphylococcus epidermidis/metabolismo , Proteínas de Bactérias/genética , Proteínas de Bactérias/metabolismo , Biofilmes , Catelicidinas , Feminino , Fímbrias Bacterianas/ultraestrutura , Humanos , Imuno-Histoquímica , Recém-Nascido , Masculino , Testes de Sensibilidade Microbiana , Gravidez , Pele/microbiologia , Infecções Cutâneas Estafilocócicas/metabolismo , Staphylococcus epidermidis/patogenicidadeRESUMO
The intestinal microbiota influences immune maturation during childhood, and is implicated in early-life allergy development. However, to directly study intestinal microbes and gut immune responses in infants is difficult. To investigate how different types of early-life gut microbiota affect immune development, we collected fecal samples from children with different allergic heredity (AH) and inoculated germ-free mice. Immune responses and microbiota composition were evaluated in the offspring of these mice. Microbial composition in the small intestine, the cecum and the colon were determined by 16S rRNA sequencing. The intestinal microbiota differed markedly between the groups of mice, but only exposure to microbiota associated with AH and known future allergy in children resulted in a T helper 17 (Th17)-signature, both systemically and in the gut mucosa in the mouse offspring. These Th17 responses could be signs of a particular microbiota and a shift in immune development, ultimately resulting in an increased risk of allergy.
RESUMO
Canine babesiosis in Hungary has always been a severe and frequent disease, attributed to infection with Babesia canis transmitted by Dermacentor reticulatus. Identification of the disease agent has been based merely on size and morphology of the intraerythrocytic parasites and no evidence has been found concerning the subspecies (genotype) of B. canis. Therefore, a molecular survey on natural Babesia infection of dogs in Hungary using PCR and sequence analysis was attempted to clarify the subspecies (genotype) and to obtain information on the occurrence of B. canis. A total of 44 blood samples from dogs showing clinical signs of babesiosis were collected. A piroplasm-specific PCR amplifying the partial 18S rRNA gene yielded an approximately 450 bp PCR product in 39 (88.6%) samples. Thirteen positive samples originated from Budapest and 26 from 21 other locations. Five PCR products were chosen randomly for sequencing. The partial 18S rDNA sequences were submitted to GenBank (accession numbers AY611729; AY611730; AY611731; AY611732 and AY611733). The sequences showed 100% homology to one another or differed by one nucleotide. BLAST search against GenBank revealed the highest similarity (99.8 or 100%) with Babesia canis canis. The implication of these data, for the further study and diagnosis of canine babesiosis is discussed.