scholarly journals VraSR Regulatory System Contributes to the Virulence of Community-Associated Methicillin-Resistant Staphylococcus aureus (CA-MRSA) in a 3D-Skin Model and Skin Infection of Humanized Mouse Model

Biomedicines ◽  
2021 ◽  
Vol 10 (1) ◽  
pp. 35
Author(s):  
Nilakshi Barua ◽  
Ying Yang ◽  
Lin Huang ◽  
Margaret Ip
Keyword(s):  
Staphylococcus Aureus ◽  
Skin Lesion ◽  
Regulatory System ◽  
Lesion Size ◽  
Skin Model ◽  
Humanized Mouse ◽  
Humanized Mouse Model ◽  
Mrsa Infection ◽  
3D Skin

The vancomycin-resistance associated sensor/regulator, VraSR two-component regulatory-system (VraSR), regulates virulence and the response of Staphylococcus aureus (SA) to environmental stress. To investigate the role of VraSR in SA skin and soft tissue infections (SSTI), we inactivated the VraSR of a clinical CA-MRSA ST30 strain by insertional mutation in vraR gene using the TargeTron-Gene Knockout System. We constructed an organotypic keratinocyte fibroblast co-culture (3D-skin model) and a humanized mouse as SSTI infection models. In the 3D-skin model, inactivation of VraSR in the strains ST30 and USA300 showed 1-log reduction in adhesion and internalization (p < 0.001) compared to the respective wildtype. The mutant strains of ST30 (p < 0.05) and USA300-LAC (p < 0.001) also exhibited reduced apoptosis. The wildtype ST30 infection in the humanized mouse model demonstrated increased skin lesion size and bacterial burden compared to BALB/c mice (p < 0.01). The response of the humanized mouse towards the MRSA infection exhibited human similarity indicating that the humanized mouse SSTI model is more suitable for evaluating the role of virulence determinants. Inactivation of VraSR in ST30 strain resulted in decreased skin lesion size in the humanized mouse SSTI model (p < 0.05) and reduction in apoptotic index (p < 0.01) when compared with the wildtype. Our results reveal that inactivating the VraSR system may be a potent anti-virulence approach to control MRSA infection.

scholarly journals Comparative Study of Two-Dimensional (2D) vs. Three-Dimensional (3D) Organotypic Kertatinocyte-Fibroblast Skin Models for Staphylococcus aureus (MRSA) Infection

2021 ◽  
Vol 23 (1) ◽  
pp. 299
Author(s):  
Nilakshi Barua ◽  
Lin Huang ◽  
Carmen Li ◽  
Ying Yang ◽  
Mingjing Luo ◽  
...  
Keyword(s):  
Staphylococcus Aureus ◽  
Cell Death ◽  
Apoptotic Index ◽  
Tunel Assay ◽  
Hacat Cells ◽  
Skin Model ◽  
Mrsa Infection ◽  
The Difference ◽  
Mrsa Strains ◽  
3D Skin

The invasion of skin tissue by Staphylococcus aureus is mediated by mechanisms that involve sequential breaching of the different stratified layers of the epidermis. Induction of cell death in keratinocytes is a measure of virulence and plays a crucial role in the infection progression. We established a 3D-organotypic keratinocyte-fibroblast co-culture model to evaluate whether a 3D-skin model is more effective in elucidating the differences in the induction of cell death by Methicillin-resistant Staphylococcus aureus (MRSA) than in comparison to 2D-HaCaT monolayers. We investigated the difference in adhesion, internalization, and the apoptotic index in HaCaT monolayers and our 3D-skin model using six strains of MRSA representing different clonal types, namely, ST8, ST30, ST59, ST22, ST45 and ST239. All the six strains exhibited internalization in HaCaT cells. Due to cell detachment, the invasion study was limited up to two and a half hours. TUNEL assay showed no significant difference in the cell death induced by the six MRSA strains in the HaCaT cells. Our 3D-skin model provided a better insight into the interactions between the MRSA strains and the human skin during the infection establishment as we could study the infection of MRSA in our skin model up to 48 h. Immunohistochemical staining together with TUNEL assay in the 3D-skin model showed co-localization of the bacteria with the apoptotic cells demonstrating the induction of apoptosis by the bacteria and revealed the variation in bacterial transmigration among the MRSA strains. The strain representing ST59 showed maximum internalization in HaCaT cells and the maximum cell death as measured by Apoptotic index in the 3D-skin model. Our results show that 3D-skin model might be more likely to imitate the physiological response of skin to MRSA infection than 2D-HaCaT monolayer keratinocyte cultures and will enhance our understanding of the difference in pathogenesis among different MRSA strains.

Abstract 5465: Role of CYP2A13 in NNK bioactivation and lung tumorigenesis:In vivostudies using a CYP2A13-humanized mouse model

2012 ◽  
Author(s):  
Vandana Megaraj ◽  
Xin Zhou ◽  
Zhihua Liu ◽  
Fang Xie ◽  
Jaime D'Agostino ◽  
...  
Keyword(s):  
Mouse Model ◽  
Humanized Mouse ◽  
Humanized Mouse Model

scholarly journals In Vivo Activity of Ceftobiprole in Murine Skin Infections Due to Staphylococcus aureus and Pseudomonas aeruginosa

2009 ◽  
Vol 54 (1) ◽  
pp. 116-125 ◽  
Author(s):  
Jeffrey Fernandez ◽  
Jamese J. Hilliard ◽  
Darren Abbanat ◽  
Wenyan Zhang ◽  
John L. Melton ◽  
...  
Keyword(s):  
Staphylococcus Aureus ◽  
Pseudomonas Aeruginosa ◽  
Bacterial Load ◽  
Lesion Size ◽  
Infection Model ◽  
Lesion Volume ◽  
Infection Models ◽  
Mrsa Infection ◽  
Response Profiles

ABSTRACT Ceftobiprole, a broad-spectrum cephalosporin with activity against methicillin-resistant Staphylococcus aureus (MRSA) (P. Hebeisen et al., Antimicrob. Agents Chemother. 45:825-836, 2001), was evaluated in a subcutaneous skin infection model with Staphylococcus aureus Smith OC 4172 (methicillin-susceptible S. aureus [MSSA]), S. aureus OC 8525 (MRSA), Pseudomonas aeruginosa OC 4351 (having an inducible AmpC β-lactamase), and P. aeruginosa OC 4354 (overproducing AmpC β-lactamase). In the MSSA and MRSA infection models, ceftobiprole, administered as the prodrug ceftobiprole medocaril, was more effective in reducing CFU/g skin (P < 0.001) than were cefazolin, vancomycin, or linezolid based on the dose-response profiles. Skin lesion volumes in MSSA-infected animals treated with ceftobiprole were 19 to 29% lower than those for cefazolin-, vancomycin-, or linezolid-treated animals (P < 0.001). In MRSA infections, lesion size in ceftobiprole-treated mice was 34% less than that with cefazolin or linezolid treatment (P < 0.001). Against P. aeruginosa, ceftobiprole at similar doses was as effective as meropenem-cilastatin in reductions of CFU/g skin, despite 8- and 32-fold-lower MICs for meropenem; both treatments were more effective than was cefepime (P < 0.001) against the inducible and overproducing AmpC β-lactamase strains of P. aeruginosa. Ceftobiprole was similar to meropenem-cilastatin and 47 to 54% more effective than cefepime (P < 0.01) in reducing the size of the lesion caused by either strain of P. aeruginosa in this study. These studies indicate that ceftobiprole is effective in reducing both bacterial load and lesion volume associated with infections due to MSSA, MRSA, and P. aeruginosa in this murine model of skin and soft tissue infection.

scholarly journals Development of a Humanized Mouse Model to Study the Role of Macrophages in Allograft Injury

2009 ◽  
Vol 87 (2) ◽  
pp. 189-197 ◽  
Author(s):  
Nancy C. Kirkiles-Smith ◽  
Martha J. Harding ◽  
Benjamin R. Shepherd ◽  
Stacey A. Fader ◽  
Tai Yi ◽  
...  
Keyword(s):  
Mouse Model ◽  
Humanized Mouse ◽  
Humanized Mouse Model

scholarly journals Household Transmission of Community-Associated Methicillin-Resistant Staphylococcus Aureus

2021 ◽  
Vol 9 ◽  
Author(s):  
Feiteng Zhu ◽  
Hemu Zhuang ◽  
Shujuan Ji ◽  
Er Xu ◽  
Lingfang Di ◽  
...  
Keyword(s):  
Staphylococcus Aureus ◽  
Methicillin Resistant ◽  
Household Transmission ◽  
Environmental Surfaces ◽  
Mass Spectrometry Identification ◽  
Colonization Dynamics ◽  
Mrsa Infection ◽  
Household Members ◽  
Mrsa Colonization

Currently, the mechanism of community-associated methicillin-resistant Staphylococcus aureus (CA-MRSA) transmission mechanism is unclear; however, it must be considered in conjunction with asymptomatic S. aureus strains colonization dynamics. This epidemiological study aimed to determine the role of the household in CA-MRSA transmission in China. Five patients with culture-confirmed CA-MRSA infection and five control patients were recruited from the Sir Run Run Shaw Hospital in Zhejiang, China, between December 2019 and January 2020. The household members of the patients, their pets, and environmental surfaces were sampled and screened for MRSA colonization. Mass spectrometry identification and antimicrobial susceptibility testing were performed on the MRSA isolates. Whole-genome sequencing and core genome multilocus sequence typing (cgMLST) were performed to determine the origin and transmission of the MRSA isolates in the households. Overall, 14 S. aureus-positive specimens (14.1%, 14/99) were obtained from the five households of patients with CA-MRSA infections, of which 12 (85.7%) were MRSA. The overall positivity of MRSA was 12.1% (12/99) among the samples from the CA-MRSA households, while no MRSA isolates were detected in the five control households. Most MRSA isolates belonged to epidemic CA-MRSA clones, such as ST59 (15/35, 42.9%) and ST508 (15/35, 42.9%). The cgMLST results confirmed that MRSA was transmitted among patients, contacts, and pets in the households and was present on environmental surfaces in the CA-MRSA patients' households. In conclusion, the study revealed that the home environment was an important MRSA reservoir. Therefore, focusing on MRSA decolonization in patients alone is not sufficient for infection control of CA-MRSA.

scholarly journals Role of VraSR in Antibiotic Resistance and Antibiotic-Induced Stress Response in Staphylococcus aureus

2006 ◽  
Vol 50 (10) ◽  
pp. 3424-3434 ◽  
Author(s):  
S. Gardete ◽  
S. W. Wu ◽  
S. Gill ◽  
A. Tomasz
Keyword(s):  
Staphylococcus Aureus ◽  
Cell Wall ◽  
Stress Response ◽  
Critical Role ◽  
Regulatory System ◽  
Experimental System ◽  
Cell Wall Synthesis ◽  
Beta Lactam ◽  
Active Inhibitor

ABSTRACT Exposure of Staphylococcus aureus to cell wall inhibitors induces massive overexpression of a number of genes, provided that the VraSR two-component sensory regulatory system is intact. Inactivation of vraS blocks this transcriptional response and also causes a drastic reduction in the levels of resistance to beta-lactam antibiotics and vancomycin. We used an experimental system in which the essential cell wall synthesis gene of S. aureus, pbpB, was put under the control of an isopropyl-β-d-thiogalactopyranoside-inducible promoter in order to induce reversible perturbations in cell wall synthesis without the use of any cell wall-active inhibitor. Changes in the level of transcription of pbpB were rapidly followed by parallel changes in the vraSR signal, and the abundance of the pbpB transcript was precisely mirrored by the abundance of the transcripts of vraSR and some additional genes that belong to the VraSR regulon. Beta-lactam resistance in S. aureus appears to involve a complex stress response in which VraSR performs the critical role of a sentinel system capable of sensing the perturbation of cell wall synthesis and allowing mobilization of genes that are essential for the generation of a highly resistant phenotype. One of the sites in cell wall synthesis “sensed” by the VraSR system appears to be a step catalyzed by PBP 2.

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