scholarly journals Comparative profiling of biofilm-production, quorum sensing system and virulence genes in human and ovine non-aureus staphylococci

2021 ◽  
Author(s):  
Elisa Azara ◽  
Carla Maria Longheu ◽  
Sonia Attene ◽  
Silvana Sanna ◽  
Marco Sale ◽  
...  
Keyword(s):  
Quorum Sensing ◽  
Health Care Professionals ◽  
Virulence Genes ◽  
Pcr Amplification ◽  
Accessory Gene ◽  
Genetic Characteristics ◽  
Adhesive Matrix ◽  
Accessory Gene Regulator ◽  
Biofilm Production ◽  
Toxic Shock Syndrome Toxin

Abstract Background: This study assessed the genetic characteristics shared by non-aureus staphylococci (NAS) responsible for human infections and those causing mastitis in dairy ewes. In a collaboration between animal and human health care professionals, we collected and identified 125 ovine and 70 human NAS isolates and compared them for biofilm production, presence of autolysins, microbial surface components recognizing adhesive matrix molecules (MSCRAMMS), pyrogenic toxins, and agr alleles regulating quorum-sensing systems. Ovine NAS included: S. epidermidis (57), S. chromogenes (29), S. haemolyticus (17), S. simulans (8), S. caprae (6), S. warneri (5), S. saprophyticus, S. intermedius, and S. muscae (1 each) while human NAS included: S. haemolyticus (28), S. epidermidis (26), S. hominis (4), S. lugdunensis (4), S. capitis (3), S. warneri (2), S. xylosus, S. pasteuri, and S. saprophyticus subsp. bovis (1 each).Results: Based on colony characteristics on Congo Red Agar, 4 (3.2%) ovine, and 49 (70%) human isolates produced biofilm. Few S. epidermidis isolates harbored the icaA/D genes coding for the polysaccharide intercellular adhesin (PIA) and the bhp, aap, and embp genes coding biofilm accumulation proteins. PCR amplification of the genes coding for autolysins (atlE and aae), microbial surface components recognizing adhesive matrix molecules (MSCRAMMs, sdrG and sdrF), enterotoxins (sea, seb, sec, sed, and see), and the toxic shock syndrome toxin (tsst), revealed that 40%, 39.2%, 47.2% and 52.8% of the sheep isolates carried atlE, aae, sdrF and sdrG, respectively, against 37.1%, 42.8%, 32.8%, and 60% of human isolates. Enterotoxins and tsst were not detected. Fifty-nine sheep isolates (all S. epidermidis, 1 S. chromogenes, and 1 S. haemolyticus) and 27 human NAS (all S. epidermidis and 1 S. warneri) were positive for the accessory gene regulator (agr), responsible for the regulation of virulence factors: agr-3se (57.8%) followed by agr-1se (36.8%) predominated in sheep, while agr-1se (65.4%), followed by agr-2se (34.6%) predominated in humans.Conclusions: This comparative study provided a detailed characterization of the putative virulence genes present in human and ovine NAS and indicated that the ability to form biofilms, observed mainly in human S. epidermidis, could be a major virulence factor facilitating colonization, infection, diffusion, and resistance.

Regulation of toxic shock syndrome toxin‐1 by the accessory gene regulator in Staphylococcus aureus is mediated by the repressor of toxins

2019 ◽  
Vol 112 (4) ◽  
pp. 1163-1177 ◽  
Author(s):  
Stephen W. Tuffs ◽  
Christine A. Herfst ◽  
Miren L. Baroja ◽  
Vladyslav A. Podskalniy ◽  
Erica N. DeJong ◽  
...  
Keyword(s):  
Staphylococcus Aureus ◽  
Toxic Shock Syndrome ◽  
Toxic Shock ◽  
Accessory Gene ◽  
Accessory Gene Regulator ◽  
Toxic Shock Syndrome Toxin

What role does the quorum-sensing accessory gene regulator system play during Staphylococcus aureus bacteremia?

2014 ◽  
Vol 22 (12) ◽  
pp. 676-685 ◽  
Author(s):  
Kimberley L. Painter ◽  
Aishwarya Krishna ◽  
Sivaramesh Wigneshweraraj ◽  
Andrew M. Edwards
Keyword(s):  
Staphylococcus Aureus ◽  
Quorum Sensing ◽  
Accessory Gene ◽  
Accessory Gene Regulator ◽  
Staphylococcus Aureus Bacteremia

scholarly journals Prevalence of Agr phase variants in Staphylococcus aureus

2020 ◽  
Vol 2 (7A) ◽  
Author(s):  
Vishal Gor ◽  
Mitsuaki Hoshi ◽  
Aya Takemura ◽  
Masato Higashide ◽  
Veronica Romero ◽  
...  
Keyword(s):  
Staphylococcus Aureus ◽  
Quorum Sensing ◽  
Virulence Factors ◽  
Human Pathogen ◽  
Accessory Gene ◽  
Accessory Gene Regulator ◽  
Inversion Event ◽  
First Time ◽  
Phase Variants ◽  
Phenotypic Reversion

Staphylococcus aureus is an important human pathogen whose success is largely attributed to its vast arsenal of virulence factors that facilitate its invasion into, and survival within, the human host. The expression of these virulence factors is controlled by the quorum sensing Accessory Gene Regulator (Agr) system. However, a large proportion of clinical S. aureus isolates are consistently found to have a mutationally inactivated Agr system. These mutants have a survival advantage in the host but are considered irreversible mutants. Here we show, for the first time, that a fraction of Agr-negative mutants can revert their Agr activity. By serially passaging Agr negative strains and screening for phenotypic reversion of haemolysis and subsequent sequencing, we identified two mutational events responsible for reversion: a genetic duplication plus inversion event and a poly(A) tract alteration. Additionally, we demonstrate that one clinical Agr-negative MRSA isolate could reproducibly generate Agr-revertant colonies with a poly(A) tract genetic mechanism. We also show that these revertants activate their Agr system upon phagocytosis. To assess the significance of our findings we screened a series of primary clinical isolates, which had undergone minimal handling post-isolation, and successfully identified a fraction which were Agr phase variants. Taken together, we propose a model where some Agr-negative S. aureus strains are phase variants who can revert their Agr activity and may act as a cryptic insurance strategy against host-mediated stress.

scholarly journals Key driving forces in the biosynthesis of autoinducing peptides required for staphylococcal virulence

2015 ◽  
Vol 112 (34) ◽  
pp. 10679-10684 ◽  
Author(s):  
Boyuan Wang ◽  
Aishan Zhao ◽  
Richard P. Novick ◽  
Tom W. Muir
Keyword(s):  
Quorum Sensing ◽  
Driving Forces ◽  
Side Chain ◽  
Accessory Gene ◽  
Accessory Gene Regulator ◽  
C Terminus ◽  
In Vitro Reconstitution ◽  
Intimate Link ◽  
Autoinducing Peptides

Staphylococci produce autoinducing peptides (AIPs) as quorum-sensing signals that regulate virulence. These AIPs feature a thiolactone macrocycle that connects the peptide C terminus to the side chain of an internal cysteine. AIPs are processed from ribosomally synthesized precursors [accessory gene regulator D (AgrD)] through two proteolytic events. Formation of the thiolactone is coupled to the first of these and involves the activity of the integral membrane protease AgrB. This step is expected to be thermodynamically unfavorable, and therefore, it is unclear how AIP-producing bacteria produce sufficient amounts of the thiolactone-containing intermediate to drive quorum sensing. Herein, we present the in vitro reconstitution of the AgrB-dependent proteolysis of an AgrD precursor from Staphylococcus aureus. Our data show that efficient thiolactone production is driven by two unanticipated features of the system: (i) membrane association of the thiolactone-containing intermediate, which stabilizes the macrocycle, and (ii) rapid degradation of the C-terminal proteolysis fragment AgrDC, which affects the reaction equilibrium position. Cell-based studies confirm the intimate link between AIP production and intracellular AgrDC levels. Thus, our studies explain the chemical principles that drive AIP production, including uncovering a hitherto unknown link between quorum sensing and peptide turnover.

scholarly journals Identification of a Staphylococcal AgrB Segment(s) Responsible for Group-Specific Processing of AgrD by Gene Swapping

2004 ◽  
Vol 186 (20) ◽  
pp. 6706-6713 ◽  
Author(s):  
Linsheng Zhang ◽  
Guangyong Ji
Keyword(s):  
Quorum Sensing ◽  
Transmembrane Protein ◽  
Specific Interaction ◽  
Accessory Gene ◽  
Sensing System ◽  
Accessory Gene Regulator ◽  
Group I ◽  
Quorum Sensing System ◽  
Group Ii ◽  
Α Helix

ABSTRACT The four gene products of the accessory gene regulator (agr) P2 operon of Staphylococcus aureus assemble a quorum-sensing system: AgrA and AgrC resemble a two-component signal transduction system, and AgrB and AgrD are required to produce an autoinducing peptide. Upon activation, this quorum-sensing system positively regulates the transcription of the P2 operon as well as the P3 operon, whose transcript, RNAIII, regulates the expression of virulence genes. Four groups of S. aureus have been identified based on the agr sequences and the group-specific interaction between the autoinducing peptide and AgrC. AgrB is a transmembrane protein involved in the processing of AgrD propeptide, and its interaction with AgrD is also group specific. In this study, a series of chimeric AgrBs were constructed by swapping between group I and group II AgrBs, and these mutants were used to analyze the group-specific segment(s) in AgrB that was responsible for AgrD processing. Our results revealed that the first transmembrane α-helix and the extracellular loop 1 of group I AgrB were decisive in the specific processing of group I AgrD. In contrast, two hydrophilic segments of group II AgrB played a crucial role in the group-specific processing of group II AgrD. We also found that several chimeric AgrBs were capable of processing AgrD from both groups, suggesting that all AgrB homologues may utilize the same or a similar mechanism in the processing of AgrDs.

scholarly journals Quorum Sensing in Staphylococcus aureus Biofilms

2004 ◽  
Vol 186 (6) ◽  
pp. 1838-1850 ◽  
Author(s):  
Jeremy M. Yarwood ◽  
Douglas J. Bartels ◽  
Esther M. Volper ◽  
E. Peter Greenberg
Keyword(s):  
Staphylococcus Aureus ◽  
Quorum Sensing ◽  
Biofilm Formation ◽  
Time Lapse ◽  
Confocal Scanning Laser Microscopy ◽  
Accessory Gene ◽  
Fluorescent Reporter ◽  
Accessory Gene Regulator ◽  
Confocal Scanning Laser ◽  
Biofilm Development

ABSTRACT Several serious diseases are caused by biofilm-associated Staphylococcus aureus, infections in which the accessory gene regulator (agr) quorum-sensing system is thought to play an important role. We studied the contribution of agr to biofilm development, and we examined agr-dependent transcription in biofilms. Under some conditions, disruption of agr expression had no discernible influence on biofilm formation, while under others it either inhibited or enhanced biofilm formation. Under those conditions where agr expression enhanced biofilm formation, biofilms of an agr signaling mutant were particularly sensitive to rifampin but not to oxacillin. Time lapse confocal scanning laser microscopy showed that, similar to the expression of an agr-independent fluorescent reporter, biofilm expression of an agr-dependent reporter was in patches within cell clusters and oscillated with time. In some cases, loss of fluorescence appeared to coincide with detachment of cells from the biofilm. Our studies indicate that the role of agr expression in biofilm development and behavior depends on environmental conditions. We also suggest that detachment of cells expressing agr from biofilms may have important clinical implications.

scholarly journals Quorum Sensing and Toxin Production in Staphylococcus aureus Osteomyelitis: Pathogenesis and Paradox

Toxins ◽  
2020 ◽  
Vol 12 (8) ◽  
pp. 516
Author(s):  
Casey E. Butrico ◽  
James E. Cassat
Keyword(s):  
Staphylococcus Aureus ◽  
Quorum Sensing ◽  
Toxin Production ◽  
High Morbidity ◽  
Invasive Infection ◽  
Accessory Gene ◽  
Accessory Gene Regulator ◽  
Production Factors ◽  
Regulatory Systems ◽  
Skeletal Homeostasis

Staphylococcus aureus is a Gram-positive pathogen capable of infecting nearly every vertebrate organ. Among these tissues, invasive infection of bone (osteomyelitis) is particularly common and induces high morbidity. Treatment of osteomyelitis is notoriously difficult and often requires debridement of diseased bone in conjunction with prolonged antibiotic treatment to resolve infection. During osteomyelitis, S. aureus forms characteristic multicellular microcolonies in distinct niches within bone. Virulence and metabolic responses within these multicellular microcolonies are coordinated, in part, by quorum sensing via the accessory gene regulator (agr) locus, which allows staphylococcal populations to produce toxins and adapt in response to bacterial density. During osteomyelitis, the Agr system significantly contributes to dysregulation of skeletal homeostasis and disease severity but may also paradoxically inhibit persistence in the host. Moreover, the Agr system is subject to complex crosstalk with other S. aureus regulatory systems, including SaeRS and SrrAB, which can significantly impact the progression of osteomyelitis. The objective of this review is to highlight Agr regulation, its implications on toxin production, factors that affect Agr activation, and the potential paradoxical influences of Agr regulation on disease progression during osteomyelitis.

A novel role for SarX in Staphylococcus epidermidis biofilm regulation

Microbiology ◽  
2011 ◽  
Vol 157 (4) ◽  
pp. 1042-1049 ◽  
Author(s):  
Sarah E. Rowe ◽  
Vivienne Mahon ◽  
Stephen G. Smith ◽  
James P. O'Gara
Keyword(s):  
Staphylococcus Epidermidis ◽  
Immunoblot Analysis ◽  
Extracellular Proteins ◽  
Pcr Analysis ◽  
Wild Type ◽  
Rt Pcr ◽  
Accessory Gene ◽  
Accessory Gene Regulator ◽  
Specific Effects ◽  
Biofilm Production

Biofilm production by staphylococci is an important virulence determinant mediated by the icaADBC-encoded polysaccharide intercellular adhesin (PIA) or by surface and extracellular proteins. Deletion of the Staphylococcus accessory regulator sarX significantly reduced biofilm-forming capacity in Staphylococcus epidermidis CSF41498, whereas multicopy sarX complemented the sarX mutant and increased wild-type biofilm production. In Staphylococcus aureus, SarX negatively regulates the accessory gene regulator (Agr) system, which in turn has strain-specific effects on biofilm regulation. Here we found that purified S. epidermidis SarX protein bound specifically to the agr P3 promoter. However RT-PCR analysis revealed that both mutation of sarX and multicopy sarX activated RNAIII transcription, making it difficult to correlate sarX-mediated biofilm regulation with altered agr activity. In contrast, RT-PCR and immunoblot analysis revealed that icaA transcription and PIA expression were decreased in the sarX mutant, whereas multicopy sarX increased ica and PIA expression. Furthermore, multicopy sarX did not promote biofilms in an icaC mutant. Finally, purified SarX protein bound specifically to the ica operon promoter. Taken together, these data reveal that the S. epidermidis SarX protein regulates the transcriptional activity of the agr and ica loci and controls the biofilm phenotype, primarily by regulating icaADBC transcription and PIA production.

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