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Morphological and Biological Characteristics of Staphylococcus aureus Biofilm Formed in the Presence of Plasma.

ABSTRACT: Characteristics of Staphylococcus aureus infections include biofilm formation, leading to the spread of bacteria to the bloodstream causing sepsis and metastatic infections. In particular, in methicillin-resistant S. aureus (MRSA) infections, biofilm formation critically hampers treatment and causes poor prognosis. We explored the biofilm formation of MRSA in the presence or absence of plasma and compared morphological characteristics, accumulation of antibiotics, and resistance to bactericidal activity, using continuous optimizing confocal reflection microscopy. Addition of plasma significantly increased biofilm formation, which is characterized by an uneven surface and aggregation of bacteria (hereafter plasma biofilm). The flow-cell system, which enabled a continuous supply of plasma, accelerated biofilm formation in both the tested strains of MRSA (BAA1556 and N315). Accumulation of green fluorescence-labeled vancomycin was observed within 5 minutes in the plasma-free biofilm, but not in the plasma biofilm. Delay of accumulation was also observed for daptomycin in plasma biofilm. Plasma biofilm bacteria were more resistant to anti-MRSA antibiotics than plasma-free biofilm bacteria. These data demonstrate that the plasma biofilm of S. aureus is substantially different from the plasma-free biofilm. Plasma biofilm, especially in the flow-cell system, could be a clinically relevant model to analyze MRSA infections and treatment.

SUBMITTER: Sato A

PROVIDER: S-EPMC6555173 | biostudies-literature | 2019 Jun

REPOSITORIES: biostudies-literature

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Morphological and Biological Characteristics of Staphylococcus aureus Biofilm Formed in the Presence of Plasma.

Sato Ayami A Yamaguchi Tetsuo T Hamada Masakaze M Ono Daisuke D Sonoda Shiro S Oshiro Takashi T Nagashima Makoto M Kato Keisuke K Okazumi Shinichi S Katoh Ryoji R Ishii Yoshikazu Y Tateda Kazuhiro K

Microbial drug resistance (Larchmont, N.Y.) 20190517 5

Characteristics of Staphylococcus aureus infections include biofilm formation, leading to the spread of bacteria to the bloodstream causing sepsis and metastatic infections. In particular, in methicillin-resistant S. aureus (MRSA) infections, biofilm formation critically hampers treatment and causes poor prognosis. We explored the biofilm formation of MRSA in the presence or absence of plasma and compared morphological characteristics, accumulation of antibiotics, and resistance to ...[more]

PMID: 31099708

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Project description:IntroductionStaphylococcus aureus is an important pathogen that can form biofilms on food contact surfaces (FCS) in the dairy industry, posing a serious food safety, and quality concern. Biofilm is a complex system, influenced by nutritional-related factors that regulate the synthesis of the components of the biofilm matrix. This study determines the prevalence of biofilm-associated genes and evaluates the development under different growth conditions and compositions of biofilms produced by S. aureus.MethodsBiofilms were developed in TSB, TSBG, TSBNaCl, and TSBGNaCl on stainless-steel (SS), with enumeration at 24 and 192 h visualized by epifluorescence and scanning electron microscopy (SEM). The composition of biofilms was determined using enzymatic and chemical treatments and confocal laser scanning microscopy (CLSM).Results and discussionA total of 84 S. aureus (SA1-SA84) strains were collected from 293 dairy industry FCS (FCS-stainless steel [n = 183] and FCS-polypropylene [n = 110]) for this study. The isolates harbored the genes sigB (66%), sar (53%), agrD (52%), clfB/clfA (38%), fnbA/fnbB (20%), and bap (9.5%). 99. In particular, the biofilm formed by bap-positive S. aureus onto SS showed a high cell density in all culture media at 192 h in comparison with the biofilms formed at 24 h (p < 0.05). Epifluorescence microscopy and SEM revealed the metabolically active cells and the different stages of biofilm formation. CLSM analysis detected extracellular polymeric of S. aureus biofilms on SS, such as eDNA, proteins, and polysaccharides. Finally, the level of detachment on being treated with DNase I (44.7%) and NaIO 4(42.4%) was greater in the biofilms developed in TSB compared to culture medium supplemented with NaCl at 24 h; however, there was no significant difference when the culture medium was supplemented with glucose. In addition, after treatment with proteinase K, there was a lower level of biomass detachment (17.7%) of the biofilm developed in TSBNaCl (p < 0.05 at 24 h) compared to that in TSB, TSBG, and TSBGNaCl (33.6, 36.9, and 37.8%, respectively). These results represent a deep insight into the composition of S. aureus biofilms present in the dairy industry, which promotes the development of more efficient composition-specific disinfection strategies.

Project description:Biofilm communities contain distinct microniches that result in metabolic heterogeneity and variability in gene expression. Previously, these niches were visualized within Staphylococcus aureus biofilms by observing differential expression of the cid and lrg operons during tower formation. In the present study, we examined early biofilm development and identified two new stages (designated "multiplication" and "exodus") that were associated with changes in matrix composition and a distinct reorganization of the cells as the biofilm matured. The initial attachment and multiplication stages were shown to be protease sensitive but independent of most cell surface-associated proteins. Interestingly, after 6 h of growth, an exodus of the biofilm population that followed the transition of the biofilm to DNase I sensitivity was demonstrated. Furthermore, disruption of the gene encoding staphylococcal nuclease (nuc) abrogated this exodus event, causing hyperproliferation of the biofilm and disrupting normal tower development. Immediately prior to the exodus event, S. aureus cells carrying a nuc::gfp promoter fusion demonstrated Sae-dependent expression but only in an apparently random subpopulation of cells. In contrast to the existing model for tower development in S. aureus, the results of this study suggest the presence of a Sae-controlled nuclease-mediated exodus of biofilm cells that is required for the development of tower structures. Furthermore, these studies indicate that the differential expression of nuc during biofilm development is subject to stochastic regulatory mechanisms that are independent of the formation of metabolic microniches. Importance: In this study, we provide a novel view of four early stages of biofilm formation by the human pathogen Staphylococcus aureus. We identified an initial nucleoprotein matrix during biofilm development that is DNase I insensitive until a critical point when a nuclease-mediated exodus of the population is induced prior to tower formation. Unlike the previously described dispersal of cells that occurs after tower development, we found that the mechanism controlling this exodus event is dependent on the Sae regulatory system and independent of Agr. In addition, we revealed that the gene encoding the secreted staphylococcal nuclease was expressed in only a subpopulation of cells, consistent with a model in which biofilms exhibit multicellular characteristics, including the presence of specialized cells and a division of labor that imparts functional consequences to the remainder of the population.

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Morphological and Biological Characteristics of Staphylococcus aureus Biofilm Formed in the Presence of Plasma.

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Morphological and Biological Characteristics of <i>Staphylococcus aureus</i> Biofilm Formed in the Presence of Plasma.

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