scholarly journals High Cell Density and Antimicrobial Persistence in Streptococcus Pyogenes 

2020 ◽  
Author(s):  
Caroline Martini ◽  
Amada Coronado ◽  
Maria Celeste Melo ◽  
Clarice Gobbi ◽  
Úrsula Lopez ◽  
...  
Keyword(s):  
Gene Expression ◽  
Cell Density ◽  
Streptococcus Pyogenes ◽  
High Cell Density ◽  
Protein Biosynthesis ◽  
Bacterial Load ◽  
Resistance Mechanisms ◽  
High Cell ◽  
Clinical Resistance ◽  
Invasive Infections

Abstract Streptococcus pyogenes (group A Streptococcus-GAS) is an important pathogen for humans. GAS has been associated with severe and invasive diseases. Despite the fact that these bacteria remain universally susceptible to penicillin, therapeutic failures have been reported in some GAS infections. Many hypotheses have been proposed to explain these antibiotic-unresponsive infections, however none of them has fully elucidated this phenomenon. In this study, antimicrobial persistence emerged when GAS strains were grown at high cell density. Strong efflux activity was detected, and gene expression assays by real-time qRT-PCR showed upregulation of some genes associated with efflux pumps in persistent cells arising in the presence of penicillin. Subsequent phenotypic reversion and whole-genome sequencing indicated that this event was due to non-inherited resistance mechanisms. The tiny persistent colonies showed downregulation of genes associated with protein biosynthesis and cell growth, as demonstrated by gene expression assays. Moreover, proteomic analyses showed that susceptible cells express higher levels of ribosome proteins. The generation of persistent cells due to high bacterial load might be an important mechanism of clinical resistance in GAS invasive infections that has been overlooked. The phenomenon described here might shed some light on the origin of therapeutic failures in S. pyogenes infections.

scholarly journals Cellular Growth Arrest and Efflux Pumps Are Associated With Antibiotic Persisters in Streptococcus pyogenes Induced in Biofilm-Like Environments

2021 ◽  
Vol 12 ◽  
Author(s):  
Caroline Lopes Martini ◽  
Amada Zambrana Coronado ◽  
Maria Celeste Nunes Melo ◽  
Clarice Neffa Gobbi ◽  
Úrsula Santos Lopez ◽  
...  
Keyword(s):  
Gene Expression ◽  
Cell Growth ◽  
Streptococcus Pyogenes ◽  
Protein Biosynthesis ◽  
Efflux Pumps ◽  
Resistance Mechanisms ◽  
Cellular Growth ◽  
Abiotic Surfaces ◽  
Invasive Infections ◽  
Group A

Streptococcus pyogenes (group A Streptococcus-GAS) is an important pathogen for humans. GAS has been associated with severe and invasive diseases. Despite the fact that these bacteria remain universally susceptible to penicillin, therapeutic failures have been reported in some GAS infections. Many hypotheses have been proposed to explain these antibiotic-unresponsive infections; however, none of them have fully elucidated this phenomenon. In this study, we show that GAS strains have the ability to form antimicrobial persisters when inoculated on abiotic surfaces to form a film of bacterial agglomerates (biofilm-like environment). Our data suggest that efflux pumps were possibly involved in this phenomenon. In fact, gene expression assays by real-time qRT-PCR showed upregulation of some genes associated with efflux pumps in persisters arising in the presence of penicillin. Phenotypic reversion assay and whole-genome sequencing indicated that this event was due to non-inherited resistance mechanisms. The persister cells showed downregulation of genes associated with protein biosynthesis and cell growth, as demonstrated by gene expression assays. Moreover, the proteomic analysis revealed that susceptible cells express higher levels of ribosome proteins. It is remarkable that previous studies have reported the recovery of S. pyogenes viable cells from tissue biopsies of patients presented with GAS invasive infections and submitted to therapy with antibiotics. The persistence phenomenon described herein brings new insights into the origin of therapeutic failures in S. pyogenes infections. Multifactorial mechanisms involving protein synthesis inhibition, cell growth impairment and efflux pumps seem to play roles in the formation of antimicrobial persisters in S. pyogenes.

scholarly journals Occurrence of antimicrobial persistence in Streptococcus pyogenes

2021 ◽  
Author(s):  
Caroline L. Martini ◽  
Amada Z. Coronado ◽  
Maria Celeste N. Melo ◽  
Clarice N. Gobbi ◽  
Úrsula S. Lopez ◽  
...  
Keyword(s):  
Gene Expression ◽  
Cell Growth ◽  
Streptococcus Pyogenes ◽  
Efflux Pump ◽  
Protein Biosynthesis ◽  
Resistance Mechanisms ◽  
Whole Genome Sequence ◽  
Abiotic Surfaces ◽  
Invasive Infections ◽  
Group A

Abstract Streptococcus pyogenes (group A Streptococcus-GAS) is an important pathogen for humans. GAS has been associated with severe and invasive diseases. Despite the fact that these bacteria remain universally susceptible to penicillin, therapeutic failures have been reported in some GAS infections. Many hypotheses have been proposed to explain these antibiotic-unresponsive infections, however none of them have fully elucidated this phenomenon. In this study, we show that GAS strains have the ability to form antimicrobial-persistent cells when growing on abiotic surfaces in a biofilm-like environment. Our data suggest that efflux activity was possibly involved in this phenomenon. In fact, gene expression assays by real-time qRT-PCR showed upregulation of some genes associated with efflux pumps in persistent cells arising in the presence of penicillin. Phenotypic reversion assay and whole-genome sequence analysis indicated that this event was due to non-inherited resistance mechanisms. The small persistent colonies showed downregulation of genes associated with protein biosynthesis and cell growth, as demonstrated by gene expression assays. Moreover, the proteomic analysis showed that susceptible cells express higher levels of ribosome proteins. It is conceivable to suppose that the generation of persistent cells by S. pyogenes might a mechanism of antimicrobial refractory during the course of real GAS invasive infections, which has been overlooked. Accordingly, the phenomenon described here might shed some light on the origin of therapeutic failures in S. pyogenes infections. Multifactorial mechanisms involving efflux pump activity, protein synthesis inhibition and cell-growth impairment seem to play roles in generation of GAS-persistent cells.

scholarly journals Ethanolamine regulates CqsR quorum-sensing signaling inVibrio cholerae

2019 ◽  
Author(s):  
Samit Watve ◽  
Kelsey Barrasso ◽  
Sarah A. Jung ◽  
Kristen J. Davis ◽  
Lisa A. Hawver ◽  
...  
Keyword(s):  
Gene Expression ◽  
Quorum Sensing ◽  
Vibrio Cholerae ◽  
Cell Density ◽  
High Cell Density ◽  
Chemical Signals ◽  
Communication Process ◽  
Control Group ◽  
Dual Function ◽  
High Cell

ABSTRACTThe pathogen that causes cholera,Vibrio cholerae, uses the cell-cell communication process known as quorum sensing (QS) to regulate virulence factor production and biofilm formation in response to changes in population density and complexity. QS is mediated through the detection of extracellular chemical signals called autoinducers. Four histidine kinases, LuxPQ, CqsS, CqsR and VpsS, have been identified as receptors to activate the key QS regulator LuxO at low cell density. At high cell density, detection of autoinducers by these receptors leads to deactivation of LuxO, resulting in population-wide gene expression changes. While the cognate autoinducers that regulate the activity of CqsS and LuxQ are known, the signals that regulate CqsR have not been determined. Here we show that the common metabolite ethanolamine specifically interacts with the ligand-binding CACHE domain of CqsRin vitroand induces the high cell-density QS response through CqsR kinase inhibition inV. choleraecells. We also identified residues in the CqsR CACHE domain important for ethanolamine detection and signal transduction. Moreover, mutations disrupting endogenous ethanolamine production inV. choleraedelay the onset of, but do not abolish, the high cell-density QS gene expression. Finally, we demonstrate that modulation of CqsR QS response by ethanolamine occurs inside animal hosts. Our findings suggest thatV. choleraeuses CqsR as a dual-function receptor to integrate information from the self-made signals as well as exogenous ethanolamine as an environmental cue to modulate QS response.IMPORTANCEMany bacteria use quorum sensing to regulate cellular processes that are important for their survival and adaptation to different environments. Quorum sensing usually depends on the detection on chemical signals called autoinducers made endogenously by the bacteria. We show here ethanolamine, a common metabolite made by various bacteria and eukaryotes, can modulate the activity of one of the quorum-sensing receptors inVibrio cholerae, the etiological agent of the disease cholera. Our results raise the possibility thatV. choleraeor other quorum-sensing bacteria can combine environmental sensing and quorum sensing to control group behaviors.

scholarly journals Formation of Spherical Palmelloid Colony with Enhanced Lipid Accumulation by Gel Encapsulation of Chlamydomonas debaryana NIES-2212

2019 ◽  
Vol 61 (1) ◽  
pp. 158-168 ◽  
Author(s):  
Toru Yoshitomi ◽  
Saeko Kaminaga ◽  
Naoki Sato ◽  
Masakazu Toyoshima ◽  
Takashi Moriyama ◽  
...  
Keyword(s):  
Gene Expression ◽  
Stationary Phase ◽  
Cell Density ◽  
Lipid Accumulation ◽  
High Cell Density ◽  
Living Cells ◽  
High Cell ◽  
Free Living ◽  
Encapsulated Cells ◽  
Alginate Gel

Abstract Microalgae such as Chlamydomonas reinhardtii accumulate triacylglycerol (TAG), which is a potential source of biofuels, under stress conditions such as nitrogen deprivation, whereas Chlamydomonas debaryana NIES-2212 has previously been identified and characterized as one of the rare species of Chlamydomonas, which massively accumulates TAG in the stationary phase without external stress. As the high density of the cells in the stationary phase was supposed to act as a trigger for the accumulation of TAG in C. debaryana, in this study, C. debaryana was encapsulated in a Ca2+-alginate gel for the culture with high cell density. We discovered that the growth of the encapsulated cells resulted in the formation of spherical palmelloid colonies with high cell density, where daughter cells with truncated flagella remained wrapped within the mother cell walls. Interestingly, gel encapsulation markedly promoted proliferation of C. debaryana cells, and the encapsulated cells reached the stationary phase earlier than that of the free-living cells. Gel encapsulation also enhanced TAG accumulation. Gene expression analysis revealed that two genes of acyltransferases, DGAT1 and DGTT3, were upregulated in the stationary phase of free-living C. debaryana. In addition, the gene expression of these acyltransferases increased earlier in the encapsulated cells than that in the free-living cells. The enhanced production of TAG by alginate gel encapsulation was not found in C. reinhardtii which is known to use a different repertoire of acyltransferases in lipid accumulation.

Sign in / Sign up

Export Citation Format

Share Document