scholarly journals Clearance of Staphylococcus aureus Nasal Carriage Is T Cell Dependent and Mediated through Interleukin-17A Expression and Neutrophil Influx

2013 ◽  
Vol 81 (6) ◽  
pp. 2070-2075 ◽  
Author(s):  
Nathan K. Archer ◽  
Janette M. Harro ◽  
Mark E. Shirtliff
Keyword(s):  
Staphylococcus Aureus ◽  
Immune Response ◽  
T Cell ◽  
Immune Responses ◽  
Neutrophil Migration ◽  
Nasal Carriage ◽  
Causal Connection ◽  
Content Type ◽  
Neutrophil Influx ◽  
Increased Risk

ABSTRACTThe anterior nares of humans are the major reservoir forStaphylococcus aureuscolonization. Approximately 20% of the healthy human population is persistently and 80% is intermittently colonized withS. aureusin the nasal cavity. Previous studies have shown a strong causal connection betweenS. aureusnasal carriage and increased risk of nosocomial infection, as well as increased carriage due to immune dysfunction. However, the immune responses that permit persistence or mediate clearance ofS. aureuson the nasal mucosa are fundamentally undefined. In this study, we developed a carriage model in C57BL/6J mice and showed that clearance begins 14 days postinoculation. In contrast, SCID mice that have a deficient adaptive immune response are unable to eliminateS. aureuseven after 28 days postinoculation. Furthermore, decolonization was found to be T cell mediated but B cell independent by evaluating carriage clearance in T-cell receptor β/δ (TCR-β/δ) knockout (KO) and IgH-μ KO mice, respectively. Upregulation of the cytokines interleukin 1β (IL-1β), KC (also termed CXC ligand 1 [CXCL1]), and IL-17A occurred following inoculation with intranasalS. aureus. IL-17A production was crucial for clearance, since IL-17A-deficient mice were unable to effectively eliminateS. aureuscarriage. Subsequently, cell differential counts were evaluated from nasal lavage fluid obtained from wild-type and IL-17A-deficient colonized mice. These counts displayed IL-17A-dependent neutrophil migration. Antibody-mediated depletion of neutrophils in colonized mice caused reduced clearance compared to that in isotype-treated controls. Our data suggest that the Th17-associated immune response is required for nasal decolonization. This response is T cell dependent and mediated via IL-17A production and neutrophil influx. Th17-associated immune responses may be targeted for strategies to mitigate distal infections originating from persistentS. aureuscarriage in humans.

scholarly journals Induction of Multifunctional Broadly Reactive T Cell Responses by a Plasmodium vivax Circumsporozoite Protein Recombinant Chimera

2015 ◽  
Vol 83 (9) ◽  
pp. 3749-3761 ◽  
Author(s):  
Monica Cabrera-Mora ◽  
Jairo Andres Fonseca ◽  
Balwan Singh ◽  
Joseli Oliveira-Ferreira ◽  
Josué da Costa Lima-Junior ◽  
...  
Keyword(s):  
Immune Response ◽  
T Cell ◽  
Immune Responses ◽  
Plasmodium Vivax ◽  
Vaccine Candidate ◽  
Chimeric Protein ◽  
Plasmodium Yoelii ◽  
Circumsporozoite Protein ◽  
Soluble Form ◽  
Content Type

Plasmodium vivaxis the most widespread species ofPlasmodium, causing up to 50% of the malaria cases occurring outside sub-Saharan Africa. An effective vaccine is essential for successful control and potential eradication. A well-characterized vaccine candidate is the circumsporozoite protein (CSP). Preclinical and clinical trials have shown that both antibodies and cellular immune responses have been correlated with protection induced by immunization with CSP. On the basis of our reported approach of developing chimericPlasmodium yoeliiproteins to enhance protective efficacy, we designed PvRMC-CSP, a recombinant chimeric protein based on theP. vivaxCSP (PvCSP). In this engineered protein, regions of the PvCSP predicted to contain human T cell epitopes were genetically fused to an immunodominant B cell epitope derived from the N-terminal region I and to repeat sequences representing the two types of PvCSP repeats. The chimeric protein was expressed in soluble form with high yield. As the immune response to PvCSP has been reported to be genetically restricted in the murine model, we tested the immunogenicity of PvRMC-CSP in groups of six inbred strains of mice. PvRMC-CSP was able to induce robust antibody responses in all the mouse strains tested. Synthetic peptides representing the allelic forms of theP. vivaxCSP were also recognized to a similar extent regardless of the mouse strain. Furthermore, the immunization regimen induced high frequencies of multifunctional CD4+and CD8+PvRMC-CSP-specific T cells. The depth and breadth of the immune responses elicited suggest that immunization with PvRMC-CSP can circumvent the genetic restriction of the immune response toP. vivaxCSP. Interestingly, PvRMC-CSP was also recognized by naturally acquired antibodies from individuals living in areas where malaria is endemic. These features make PvRMC-CSP a promising vaccine candidate for further development.

scholarly journals NP108, an Antimicrobial Polymer with Activity against Methicillin- and Mupirocin-Resistant Staphylococcus aureus

2017 ◽  
Vol 61 (9) ◽  
Author(s):  
Derry K. Mercer ◽  
Laura K. Katvars ◽  
Fiona Hewitt ◽  
Daniel W. Smith ◽  
Jennifer Robertson ◽  
...  
Keyword(s):  
Staphylococcus Aureus ◽  
Surgical Site Infections ◽  
Standard Of Care ◽  
Nasal Carriage ◽  
Building Blocks ◽  
Water Soluble ◽  
Current Standard ◽  
Content Type ◽  
Increased Risk ◽  
Clinically Significant

ABSTRACT Staphylococcus aureus is a clinically significant human pathogen that causes infectious diseases ranging from skin and soft tissue infections (SSTI) and health care-associated infections (HAI) to potentially fatal bacteremia and endocarditis. Nasal carriage of S. aureus, especially for persistent carriage, is associated with an increased risk of subsequent infection, particularly nosocomial and surgical site infections (SSI), usually via autoinfection. NP108 is a cationic antimicrobial polymer composed of generally recognized as safe (GRAS) amino acid building blocks. NP108 is broad spectrum and rapidly bactericidal (3-log kill in ≤3 h), killing bacteria by membrane disruption and cell lysis. NP108, contrary to many antibiotics, shows equally effective antimicrobial activity against a variety of S. aureus (MIC100 = 8 to 500 mg/liter) and S. epidermidis (MIC100 = 4 to 8 mg/liter) isolates, whether exponentially growing or in stationary phase. NP108 is antimicrobially active under nutrient-limiting conditions similar to those found in the anterior nares (MIC100 = 8 mg/liter) and kills antibiotic-resilient small colony variants (MIC100 = 32 mg/liter) and S. aureus biofilms (prevention, MIC100 = 1 to 4 mg/liter; eradication, MIC100 ≥ 31.25 mg/liter). NP108 is active against isolates of S. aureus resistant to the current standard-of-care decolonization agent, mupirocin, with no significant increase in the MIC100. NP108 is water soluble and has been formulated into compatible aqueous gel vehicles for human use in which antimicrobial efficacy is retained (2.0% [wt/vol]). NP108 is a potential nonantibiotic antimicrobial alternative to antibiotics for the nasal decolonization of S. aureus, with clear advantages in its mechanism of action over the existing gold standard, mupirocin.

scholarly journals Population Analysis of Staphylococcus aureus Reveals a Cryptic, Highly Prevalent Superantigen SElW That Contributes to the Pathogenesis of Bacteremia

mBio ◽  
2020 ◽  
Vol 11 (5) ◽  
Author(s):  
Manouk Vrieling ◽  
Stephen W. Tuffs ◽  
Gonzalo Yebra ◽  
Marleen Y. van Smoorenburg ◽  
Joana Alves ◽  
...  
Keyword(s):  
Staphylococcus Aureus ◽  
Immune Response ◽  
T Cell ◽  
Bacterial Load ◽  
Host Immune Response ◽  
Start Codon ◽  
Dependent Manner ◽  
Epidemic Clone ◽  
Content Type

ABSTRACT Staphylococcal superantigens (SAgs) are a family of secreted toxins that stimulate T cell activation and are associated with an array of diseases in humans and livestock. Most SAgs produced by Staphylococcus aureus are encoded by mobile genetic elements, such as pathogenicity islands, bacteriophages, and plasmids, in a strain-dependent manner. Here, we carried out a population genomic analysis of >800 staphylococcal isolates representing the breadth of S. aureus diversity to investigate the distribution of all 26 identified SAg genes. Up to 14 SAg genes were identified per isolate with the most common gene selw (encoding a putative SAg, SElW) identified in 97% of isolates. Most isolates (62.5%) have a full-length open reading frame of selw with an alternative TTG start codon that may have precluded functional characterization of SElW to date. Here, we demonstrate that S. aureus uses the TTG start codon to translate a potent SAg SElW that induces Vβ-specific T cell proliferation, a defining feature of classical SAgs. SElW is the only SAg predicted to be expressed by isolates of the CC398 lineage, an important human and livestock epidemic clone. Deletion of selw in a representative CC398 clinical isolate, S. aureus NM001, resulted in complete loss of T cell mitogenicity in vitro, and in vivo expression of SElW by S. aureus increased the bacterial load in the liver during bloodstream infection of SAg-sensitive HLA-DR4 transgenic mice. Overall, we report the characterization of a novel, highly prevalent, and potent SAg that contributes to the pathogenesis of S. aureus infection. IMPORTANCE Staphylococcus aureus is an important human and animal pathogen associated with an array of diseases, including life-threatening necrotizing pneumonia and infective endocarditis. The success of S. aureus as a pathogen has been linked in part to its ability to manipulate the host immune response through the secretion of toxins and immune evasion molecules. The staphylococcal superantigens (SAgs) have been studied for decades, but their role in S. aureus pathogenesis is not well understood, and an appreciation for how SAgs manipulate the host immune response to promote infection may be crucial for the development of novel intervention strategies. Here, we characterized a widely prevalent, previously cryptic, staphylococcal SAg, SElW, that contributes to the severity of S. aureus infections caused by an important epidemic clone of S. aureus CC398. Our findings add to the understanding of staphylococcal SAg diversity and function and provide new insights into the capacity of S. aureus to cause disease.

scholarly journals CD4 T Cell Antigens from Staphylococcus aureus Newman Strain Identified following Immunization with Heat-Killed Bacteria

2012 ◽  
Vol 19 (4) ◽  
pp. 477-489 ◽  
Author(s):  
Paulraj K. Lawrence ◽  
Bachra Rokbi ◽  
Nadège Arnaud-Barbe ◽  
Eric L. Sutten ◽  
Junzo Norimine ◽  
...  
Keyword(s):  
Staphylococcus Aureus ◽  
T Cell ◽  
Reverse Genetics ◽  
Vaccine Development ◽  
Protein A ◽  
Cd4 T Cell ◽  
Content Type ◽  
Intramammary Infections ◽  
T Cell Antigens ◽  
Ifn Γ

ABSTRACTStaphylococcus aureusis a commensal bacterium associated with the skin and mucosal surfaces of humans and animals that can also cause chronic infection. The emergence of antibiotic-resistant strains such as methicillin-resistantS. aureus(MRSA) and strains causing chronic intramammary infections (IMI) in cows results in severe human and livestock infections. Conventional approaches to vaccine development have yielded only a few noneffective vaccines against MRSA or IMI strains, so there is a need for improved vaccine development. CD4 T lymphocytes are required for promoting gamma interferon (IFN-γ) mediated immunoglobulin isotype switching in B lymphocytes to produce high-affinity IgG antibodies and IFN-γ-mediated phagocyte activation for an effective resolution of bacterial infection. However, the lack of known CD4 T cell antigens fromS. aureushas made it difficult to design effective vaccines. The goal of this study was to identifyS. aureusproteins recognized by immune CD4 T cells. Using a reverse genetics approach, 43 antigens were selected from theS. aureusNewman strain. These included lipoproteins, proteases, transcription regulators, an alkaline shock protein, conserved-domain proteins, hemolysins, fibrinogen-binding protein, staphylokinase, exotoxin, enterotoxin, sortase, and protein A. Screening of expressed proteins for recall T cell responses in outbred, immune calves identified 13 proteins that share over 80% sequence identity among MRSA or IMI strains. These may be useful for inclusion in a broadly protective multiantigen vaccine against MRSA or IMI.

scholarly journals Safety and Immunogenicity of a Novel Staphylococcus aureus Vaccine: Results from the First Study of the Vaccine Dose Range in Humans

2010 ◽  
Vol 17 (12) ◽  
pp. 1868-1874 ◽  
Author(s):  
Clayton Harro ◽  
Robert Betts ◽  
Walter Orenstein ◽  
Eun-Jeong Kwak ◽  
Howard E. Greenberg ◽  
...  
Keyword(s):  
Staphylococcus Aureus ◽  
Immune Response ◽  
Adverse Events ◽  
Immune Responses ◽  
Geometric Mean ◽  
Dose Range ◽  
Vaccine Dose ◽  
Double Blind Study ◽  
Mean Concentration ◽  
Positive Immune Response

ABSTRACT Merck V710 is a novel vaccine containing the conserved Staphylococcus aureus iron surface determinant B shown to be protective in animal models. A phase I, multicenter, double-blind study of the dose range was conducted to assess the immunogenicity and safety of an adjuvanted liquid formulation of V710. A total of 124 adults (18 to 55 years of age) were randomized 1:1:1:1 to receive one 0.5-ml intramuscular injection of V710 (5 μg, 30 μg, or 90 μg) or saline placebo. A positive immune response was defined as at least a 2-fold increase in IsdB-specific IgG levels from baseline levels. Local and systemic adverse events were assessed for 5 and 14 days, respectively, following vaccination. Positive immune responses were detected in 12 (67%) of the 18 subjects in the groups receiving 30 and 90 μg V710 tested at day 10. At day 14, a significantly greater proportion of subjects manifested a positive immune response with higher geometric mean concentrations in the V710 30-μg (86%; geometric mean concentration of 116 μg/ml) and 90-μg (87%; geometric mean concentration of 131 μg/ml) dose groups than in the V710 5-μg (29%; geometric mean concentration of 51 μg/ml) or placebo (4%; geometric mean concentration of 23 μg/ml) groups. Immune responses were durable through day 84. Subjects <40 and ≥40 years of age had comparable immune responses. The most common adverse events were injection-site pain, nausea, fatigue, and headache, usually of mild intensity. No immediate reactions or serious adverse events were reported. In this first study of V710 in humans, a single 30-μg or 90-μg dose was more immunogenic than the 5-μg dose or placebo. Immune responses were evident by 10 to 14 days after vaccination in most responders.

scholarly journals Failure To Recruit Anti-Inflammatory CD103+Dendritic Cells and a Diminished CD4+Foxp3+Regulatory T Cell Pool in Mice That Display Excessive Lung Inflammation and Increased Susceptibility to Mycobacterium tuberculosis

2012 ◽  
Vol 80 (3) ◽  
pp. 1128-1139 ◽  
Author(s):  
Chaniya Leepiyasakulchai ◽  
Lech Ignatowicz ◽  
Andrzej Pawlowski ◽  
Gunilla Källenius ◽  
Markus Sköld
Keyword(s):  
Immune Response ◽  
Dendritic Cells ◽  
Mycobacterium Tuberculosis ◽  
T Cell ◽  
Bacterial Growth ◽  
Lung Inflammation ◽  
Chronic Infection ◽  
Host Immune Response ◽  
Content Type ◽  
Tnf Α

Susceptibility toMycobacterium tuberculosisis characterized by excessive lung inflammation, tissue damage, and failure to control bacterial growth. To increase our understanding of mechanisms that may regulate the host immune response in the lungs, we characterized dendritic cells expressing CD103 (αEintegrin) (αE-DCs) and CD4+Foxp3+regulatory T (Treg) cells duringM. tuberculosisinfection. In resistant C57BL/6 and BALB/c mice, the number of lung αE-DCs increased dramatically duringM. tuberculosisinfection. In contrast, highly susceptible DBA/2 mice failed to recruit αE-DCs even during chronic infection. Even though tumor necrosis factor alpha (TNF-α) is produced by multiple DCs and macrophage subsets and is required for control of bacterial growth, αE-DCs remained TNF-α negative. Instead, αE-DCs contained a high number of transforming growth factor beta-producing cells in infected mice. Further, we show that Tregcells in C57BL/6 and DBA/2 mice induce gamma interferon during pulmonary tuberculosis. In contrast to resistant mice, the Tregcell population was diminished in the lungs, but not in the draining pulmonary lymph nodes (PLN), of highly susceptible mice during chronic infection. Tregcells have been reported to inhibitM. tuberculosis-specific T cell immunity, leading to increased bacterial growth. Still, despite the reduced number of lung Tregcells in DBA/2 mice, the bacterial load in the lungs was increased compared to resistant animals. Our results show that αE-DCs and Tregcells that may regulate the host immune response are increased inM. tuberculosis-infected lungs of resistant mice but diminished in infected lungs of susceptible mice.

scholarly journals Dairy Heifers Naturally Exposed toFasciola hepaticaDevelop a Type 2 Immune Response and Concomitant Suppression of Leukocyte Proliferation

2017 ◽  
Vol 86 (1) ◽  
Author(s):  
John Graham-Brown ◽  
Catherine Hartley ◽  
Helen Clough ◽  
Aras Kadioglu ◽  
Matthew Baylis ◽  
...  
Keyword(s):  
Immune Response ◽  
Immune Responses ◽  
Peripheral Blood ◽  
Serum Antibody ◽  
Enzyme Linked Immunosorbent Assay ◽  
Mixed Effect ◽  
Content Type ◽  
Grazing Season ◽  
Type 2 Immune Response

ABSTRACTFasciola hepaticais a parasitic trematode of global importance in livestock. Control strategies reliant on anthelmintics are unsustainable due to the emergence of drug resistance. Vaccines are under development, but efficacies are variable. Evidence from experimental infection suggests that vaccine efficacy may be affected by parasite-induced immunomodulation. Little is known about the immune response toF. hepaticafollowing natural exposure. Hence, we analyzed the immune responses over time in calves naturally exposed toF. hepaticainfection. Cohorts of replacement dairy heifer calves (n= 42) with no prior exposure toF. hepatica, on three commercial dairy farms, were sampled over the course of a grazing season. Exposure was determined through anF. hepatica-specific serum antibody enzyme-linked immunosorbent assay (ELISA) and fluke egg counts. Concurrent changes in peripheral blood leukocyte subpopulations, lymphocyte proliferation, and cytokine responses were measured. Relationships between fluke infection and immune responses were analyzed by using multivariable linear mixed-effect models. All calves from one farm showed evidence of exposure, while cohorts from the remaining two farms remained negative over the grazing season. A type 2 immune response was associated with exposure, with increased interleukin-4 (IL-4) production, IL-5 transcription, and eosinophilia. Suppression of parasite-specific peripheral blood mononuclear cell (PBMC) proliferation was evident, while decreased mitogen-stimulated gamma interferon (IFN-γ) production suggested immunomodulation, which was not restricted to parasite-specific responses. Our findings show that the global immune response is modulated toward a nonproliferative type 2 state following natural challenge withF. hepatica. This has implications in terms of the timing of the administration of vaccination programs and for host susceptibility to coinfecting pathogens.

scholarly journals Optimized Adenovirus-Antibody Complexes Stimulate Strong Cellular and Humoral Immune Responses against an Encoded Antigen in Naïve Mice and Those with Preexisting Immunity

2011 ◽  
Vol 19 (1) ◽  
pp. 84-95 ◽  
Author(s):  
Jin Huk Choi ◽  
Joe Dekker ◽  
Stephen C. Schafer ◽  
Jobby John ◽  
Craig E. Whitfill ◽  
...  
Keyword(s):  
Immune Response ◽  
T Cell ◽  
Immune Responses ◽  
Neutralizing Antibodies ◽  
T Cell Responses ◽  
Transduction Efficiency ◽  
Virus Antibody ◽  
Cell Responses

ABSTRACTThe immune response to recombinant adenoviruses is the most significant impediment to their clinical use for immunization. We test the hypothesis that specific virus-antibody combinations dictate the type of immune response generated against the adenovirus and its transgene cassette under certain physiological conditions while minimizing vector-induced toxicity.In vitroandin vivoassays were used to characterize the transduction efficiency, the T and B cell responses to the encoded transgene, and the toxicity of 1 × 1011adenovirus particles mixed with different concentrations of neutralizing antibodies. Complexes formed at concentrations of 500 to 0.05 times the 50% neutralizing dose (ND50) elicited strong virus- and transgene-specific T cell responses. The 0.05-ND50formulation elicited measurable anti-transgene antibodies that were similar to those of virus alone (P= 0.07). This preparation also elicited very strong transgene-specific memory T cell responses (28.6 ± 5.2% proliferation versus 7.7 ± 1.4% for virus alone). Preexisting immunity significantly reduced all responses elicited by these formulations. Although lower concentrations (0.005 and 0.0005 ND50) of antibody did not improve cellular and humoral responses in naïve animals, they did promote strong cellular (0.005 ND50) and humoral (0.0005 ND50) responses in mice with preexisting immunity. Some virus-antibody complexes may improve the potency of adenovirus-based vaccines in naïve individuals, while others can sway the immune response in those with preexisting immunity. Additional studies with these and other virus-antibody ratios may be useful to predict and model the type of immune responses generated against a transgene in those with different levels of exposure to adenovirus.

scholarly journals Protection againstStaphylococcus aureusColonization and Infection by B- and T-Cell-Mediated Mechanisms

mBio ◽  
2018 ◽  
Vol 9 (5) ◽  
Author(s):  
Fan Zhang ◽  
Olivia Ledue ◽  
Maria Jun ◽  
Cibelly Goulart ◽  
Richard Malley ◽  
...  
Keyword(s):  
T Cell ◽  
Soft Tissue ◽  
Bacterial Infections ◽  
Vaccine Development ◽  
Pathological Condition ◽  
Treatment Options ◽  
Immune Defense ◽  
Invasive Infection ◽  
Content Type ◽  
Increased Risk

ABSTRACTStaphylococcus aureusis a major cause of morbidity and mortality worldwide.S. aureuscolonizes 20 to 80% of humans at any one time and causes a variety of illnesses. Strains that are resistant to common antibiotics further complicate management.S. aureusvaccine development has been unsuccessful so far, largely due to the incomplete understanding of the mechanisms of protection against this pathogen. Here, we studied the role of different aspects of adaptive immunity induced by anS. aureusvaccine in protection againstS. aureusbacteremia, dermonecrosis, skin abscess, and gastrointestinal (GI) colonization. We show that, depending on the challenge model, the contributions of vaccine-inducedS. aureus-specific antibody and Th1 and Th17 responses to protection are different: antibodies play a major role in reducing mortality duringS. aureusbacteremia, whereas Th1 or Th17 responses are essential for prevention ofS. aureusskin abscesses and the clearance of bacteria from the GI tract. Both antibody- and T-cell-mediated mechanisms contribute to prevention ofS. aureusdermonecrosis. Engagement of all three immune pathways results in the most robust protection under each pathological condition. Therefore, our results suggest that eliciting multipronged humoral and cellular responses toS. aureusantigens may be critical to achieve effective and comprehensive immune defense against this pathogen.IMPORTANCES. aureusis a leading cause of healthcare- and community-associated bacterial infections.S. aureuscauses various illnesses, including bacteremia, meningitis, endocarditis, pneumonia, osteomyelitis, sepsis, and skin and soft tissue infections.S. aureuscolonizes between 20 and 80% of humans; carriers are at increased risk for infection and transmission to others. The spread of multidrug-resistant strains limits antibiotic treatment options. Vaccine development againstS. aureushas been unsuccessful to date, likely due to an inadequate understanding about the mechanisms of immune defense against this pathogen. The significance of our work is in illustrating the necessity of generating multipronged B-cell, Th1-, and Th17-mediated responses toS. aureusantigens in conferring enhanced and broad protection againstS. aureusinvasive infection, skin and soft tissue infection, and mucosal colonization. Our work thus, provides important insights for future vaccine development against this pathogen.

scholarly journals Nasal carriage of Staphylococcus aureus in farm animals and breeders in North of Morocco

2020 ◽  
Author(s):  
Nadira Mourabit ◽  
Abdelhay Arakrak ◽  
Mohammed Bakkali ◽  
Zeineb Zian ◽  
Joaira Bakkach ◽  
...  
Keyword(s):  
Staphylococcus Aureus ◽  
Antimicrobial Susceptibility ◽  
Virulence Genes ◽  
Nasal Carriage ◽  
High Rate ◽  
Farm Animals ◽  
Carriage Rate ◽  
Increased Risk ◽  
Significant Difference ◽  
Mrsa Strains

Abstract Background: The objectives of this study were to determine for the first time, in Morocco, the nasal carriage rate, antimicrobial susceptibility profiles and virulence genes of Staphylococcus. aureus isolated from animals and breeders in close contact.Methods: From 2015 to 2016, 421 nasal swab samples were collected from 26 different livestock areas in Tangier. Antimicrobial susceptibility phenotypes were determined by disk diffusion according to EUCAST 2015. The presence of nuc , mec A, mec C, lukS/F-PV, and tst genes were determined by Polymerase Chain Reaction (PCR) for all isolates.Results: The overall S. aureus nasal carriage rate was low in animals (9.97%) and high in breeders (60%) with a statistically significant difference, (OR= 13.536; 95% CI = 7.070- 25.912; p< 0.001). In general, S. aureus strains were susceptible to the majority of antibiotics and the highest resistance rates were found against tetracycline (16.7% in animals and 10% in breeders). No Methicillin-Resistant S. aureus (MRSA) was detected in animals and breeders. A high rate of tst and lukS/F-PV genes has been recovered only from animals (11.9% and 16.7%, respectively).Conclusion: Despite the lower rate of nasal carriage of S. aureus and the absence of MRSA strains in our study, S. aureus strains harbored a higher frequency of tst and lukS/F-PV virulence genes, which is associated to an increased risk of infection dissemination in humans. This highlights the need for further larger and multi-center studies to better define the transmission of the pathogenic S. aureus between livestock, environment, and humans.

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