Staphylococcus pathogenesis

Staphylococcus pathogenesis. ) Staphylococcus is usually either beta hemolytic or not hemolytic at all (called gamma hemolysis). aureus mastitis remains a major Apr 11, 2024 · The symptoms of an S. Oct 23, 2018 · Staphylococcus caprae (S. aureus May 3, 2023 · the family Staphylococcaceae with a spherical shape that forms grape-like clusters, is a. It consists of clustered cocci and forms white circular colonies when grown on blood agar. Polymicrobial infections involving Staphylococcus aureus exhibit enhanced disease severity and morbidity. Although herd management programs have helped to reduce the number of clinical cases, S. Staphylococcus aureus causes many types of human infections and syndromes-most notably skin and soft tissue infections. Dec 28, 2023 · Staphylococcus aureus stands as one of the most pervasive pathogens given its morbidity and mortality worldwide due to its roles as an infectious agent that causes a wide variety of diseases ranging from moderately severe skin infections to fatal pneumonia and sepsis. The outcome is pathogen proliferation, but not commensal. The organism produces coagulase, which helps to differentiate it from other species of the same genus. epidermidis is capable of establishing a lifelong commensal relationship with humans that begins early in life. However, in hospitals, it can also grow in biofilms that form on catheters, implants, or other devices that Dec 13, 2022 · Ecology and Pathogenesis Staphylococcus borealis is coagulase negative which means it colonizes different niches of the human skin and is a part of the commensal human host microbiota. [1] These results suggest that key aspects of S. equorum that are generally inconspicuous regarding clinical occurrences. aureus are the most frequent causes of nosocomial infections and infections on indwelling medical devices, which characteristically involve biofilms. carnosus, S. pyogenes infections can result in the postinfectious sequela acute rheumatic fever and post-streptococcal glomerulonephritis. aureus) and also the emerging CoNS, including Staphylococcus epidermidis ( S. The chapter also discusses the role of coagulase-negative species in both human and veterinary Staphylococcus aureus is the most pathogenic; it typically causes skin infections and sometimes pneumonia, endocarditis, and osteomyelitis. (See "Infection due to coagulase-negative staphylococci: Clinical manifestations" and "Infection due to coagulase-negative staphylococci: Treatment" . Most pathogenic strains are capsulated. epidermidis is a member of the normal microbiota of the skin, where it is generally avirulent. commensal that is often present asymptomatically on parts of the human body [. Indeed, the ability to limit toxin production may provide an important mechanism for persistence, dissemination, and development of invasive disease within an individual human host. Pathogenesis augmentation can be mediated by particulate cell wall peptidoglycan, reducing the Abstract. Coagulase: Staphylococcus aureus produces two types of coagulases, bound coagulase and free coagulase. aureus infection, including MRSA, depend on the part of the body that is infected. However, the incidence of infections due to Staphylococcus epidermidis (S epidermidis) and other coagulase-negative staphylococci (CoNS) also has been steadily rising. caprae) is a catalase-positive, coagulase-negative organism that was first isolated from goat milk, and was later found to colonize healthy human skin, nails, and nasal mucosa. Although many antibiotics and phages are used to control S. Some strains of this group are used in the food industry and can be graded as non-pathogenic. May 5, 2016 · Abstract. aureus forms a complex structure of extracellular polymeric biofilm that provides a fully secured and functional environment for the formation of microcolonies, their sustenance and Jul 16, 2021 · Staphylococcus aureus is a nosocomial bacterium causing different infectious diseases, ranging from skin and soft tissue infections to more serious and life-threatening infections such as septicaemia. Unlike other CoNS, however, S. Besides the highly and medium-pathogenic staphylococci, the genus comprises also species like S. Staphylococcus aureus, an important pathogen of humans and other warm-blooded animals, is also capable of killing the nematode Caenorhabditis elegans. A major contribution to the success of S. These various species of Staphylococcus are clinically important as 30% of the healthy human population is colonized with various Staphylococcus spp. In predisposed patients, there is a high risk of transformation of BSI episodes to sepsis. Like most other coagulase-negative Staphylococci, S. intermedius is limited. aureus) is a Gram-positive pathogenic bacterium and is a major cause of different infectious illnesses in humans and animals [1,2]. Mar 24, 2022 · Staphylococcus aureus is a leading cause of bovine mastitis worldwide. Oct 10, 2019 · Staphylococcus aureus endocarditis is a deadly, but understudied heart disease. aureus has a high level of antibiotic resistance and is a common cause of infections in hospitals and the community. The study was to determine S. Painful. Learn about its pathogenesis, antimicrobial resistance, and treatment options from this comprehensive review article. We recently published a transposon sequencing (Tn-seq) screen in a mouse acute pneumonia model and identified a hypothetical gene (SAUSA300_1902, pgl) with similarity to a lactonase of Escherichia coli involved in the pentose This overview addresses current knowledge of the pathogenesis of infections due to CoNS and particularly focuses on virulence factors of the species Staphylococcus epidermidis. S. Despite its clinical importance, our understanding of the population genetics and pathogenesis of S. Despite some improved understanding of disease pathogenesis, progress towards new methods for the control of intramammary infections (IMI) has been limited, particularly in the field Here we show that the virulence of the human pathogen Staphylococcus aureus is augmented by native, polymicrobial, commensal skin flora and individual species acting as 'proinfectious agents'. Westin. lugdunensis in humans ranges from a harmless skin commensal to a life-threatening pathogen (as with infective endocarditis). It is also a commensal bacterium colonizing up to two-thirds of the human population, depending upon patient characteristics The epidemiology, microbiology, and pathogenesis of CoNS will be reviewed here. These illnesses may range from simple skin and soft tissue infections to more serious and life threatening conditions such as blood infections (bacteraemia Jun 23, 2021 · Staphylococcus aureus is a nosocomial bacterium causing different infectious diseases, ranging from skin and soft tissue infections to more serious and life-threatening infections such as septicaemia. For this reason, vancomycin, a glycopeptide antibiotic, is commonly used to combat MRSA. aureus-related infectious diseases Jan 19, 2017 · Staphylococcus aureus is an eminent human pathogen that can colonize the human host and cause severe life-threatening illnesses. Staphylococcus aureus. Mar 4, 2015 · Staphylococcus aureus causes many types of human infections and syndromes—most notably skin and soft tissue infections. Some strains elaborate toxins that cause gastroenteritis, scalded skin syndrome, and toxic shock syndrome. Pathogenesis. However, a direct involvement of lipase in the pathogenesis of S. Diagnosis is by Gram stain and culture. Staphylococcus epidermidis is a permanent member of the normal human microbiota, commonly found on skin, and mucous membranes. Most pathogenic strains have been coagulase-positive; however, coagulase-negative Staphylococcus May 25, 2022 · Septic arthritis. aureus skin infections, including MRSA, appear as a bump or infected area on the skin that might be: Red. Staphylococcus epidermidis and S. Staphylococcus aureus is a major pathogen of the eye able to infect the tear duct, eyelid, conjunctiva, cornea, anterior and posterior chambers, and the vitreous chamber. El-Gazzar. Aug 12, 2020 · 2. Moreover, it causes invasive infections like Aug 8, 2023 · Staphylococcus aureus (S. [1] Infections are common both in community-acquired as well as hospital-acquired settings and treatment remains challenging to manage due to the emergence of multi-drug resistant strains such as MRSA (Methicillin-Resistant Staphylococcus aureus). aureus remains to be demonstrated. By adhering to tissue surface moieties of the host via specific adhesins, S. Staphylococcus aureus is an opportunistic Gram-positive pathogen that often causes hospital- and community-acquired infections. aureus, this pathogen has the excellent ability to defend itself best [[23], [24], [25]]. The numerous virulence factors and toxins Oct 20, 2019 · A similar analysis of predicted virulence factors, revealed that several genes associated with pathogenesis (including, for example, ica, nuc, and ssp), which are commonly found in the genomes of pathogenic staphylococci such as Staphylococcus haemolyticus (SH) and Staphylococcus saprophyticus (SS), are observed also in the SAR strains for Aug 14, 2015 · Staphylococcus aureus, a bacterial commensal of the human nares and skin, is a frequent cause of soft tissue and bloodstream infections. aureus is found in the May 18, 2021 · Over time, numerous Staphylococcus species were discovered, consisting of more than 45 staphylococcal species and 24 subspecies classified using molecular methods . Staphylococci are common bacterial colonizers of the skin and mucous membranes of humans and other mammals 4. Treatment of S. haemolyticus is its ability to form biofilms, which play an essential role in the establishment of Jan 10, 2018 · Abstract. Most cases of pneumonia are secondary to inhalation of the infecting agent. The expression of these. The mechanisms that S. Warm to the touch. Mar 23, 2012 · During infection, Staphylococcus aureus produces multiple enzymes that enable it to invade and destroy host tissues and metastasize to other sites. Severe pain in the affected joint. A hallmark of staphylococcal infections is their frequent 3. Gram-positive and Gram-negative bacteria have the ability to sense and respond to the environment through two-component regulatory systems, which classically consist of a histidine kinase and a response regulator []. This bacterium can reside in and infect a wide range of host tissues, ranging from superficial surfaces like the skin to deeper tissues such as in the gastrointestinal tract, heart and bones. 1. epidermidis) and S. Staphylococcus epidermidis, on the other hand, is an opportunistic pathogen that is among the most frequent causes of nosocomial disease. aureus produces a variety of exotoxins that serve as important virulence factors in S. haemolyticus, especially strains that cause nosocomial infections, are more resistant to antibiotics than other Apr 18, 2024 · Staphylococcal infections usually are caused by Staphylococcus aureus (S aureus). Oct 31, 2013 · Staphylococcus epidermidis is the most frequently encountered member of the coagulase-negative staphylococci on human epithelial surfaces. It may also present in immunocompromised adults or those with severe renal disease. epidermidis uses to survive during infection are in general of a passive Methicillin-resistant Staphylococcus aureus (MRSA, often pronounced / ˈmɜːrsə / or / ɛm ɑːr ɛs eɪ / ), is one of a number of greatly feared strains of S. Staphylococci are among the most frequent human microbiota components associated with the high level of bloodstream infection (BSI) episodes. 7 MAC may also explain the anatomical predilection of S hyicus to destroy the annulus whilst sparing the valve. aureus, the history and epidemiology of S. Staphylococcus aureus is a major human pathogen that causes a wide range of clinical infections. aureus. Feb 22, 2019 · Abstract. These toxins kill the polymorphonuclear phagocytes (PMNs), disrupt epithelial and endothelial barriers, and lyse erythrocytes to provide iron for bacterial growth. In general, bacterial cells need to survive and remain stable to propagate Staphylococcus aureus is a gram-positive coccus that looks like cluster of grapes under the microscope. Polymorphonuclear leukocytes (neutrophils) are the primary cellular host defense Mar 9, 2020 · Members of the genus Staphylococcus still represent a topic of great relevance due to the numerous types of infections they cause in humans and animals. ]. Apr 25, 2024 · Staphylococcus lugdunensis is a coagulase-negative staphylococcus (CoNS). In its natural environments such as the human skin or mucosa, they are usually harmless. aureus which have become resistant to most β-lactam antibiotics. It is also a catalase-positive and facultative anaerobe. Staphylococci have emerged as important pathogens for both nosocomial and community-acquired infections in people. Infections occur frequently as a consequence of S. This review aims to work out the differences between Feb 15, 2022 · Fig. The presence of diabetes is also a risk factor for S. The image below depicts embolic lesions in patient with S aureus endocarditis. aureus infections is complicated by antibiotic resistance and a working May 3, 2023 · Staphylococcus aureus, a Gram-positive, coagulase-positive pathogen belonging to the family Staphylococcaceae with a spherical shape that forms grape-like clusters, is a commensal that is often present asymptomatically on parts of the human body [ 1 ]. hominis is also known to cause various nosocomial or hospital-acquired infections and Oct 11, 2017 · Staphylococcus lugdunensis ( S. The genus Staphylococcus contains dozens of species, but S aureus is the most pathogenic. aureus die over the course of several days in a process that is correlated with the accumulation of bacteria within the nematode Jan 27, 2023 · Invasive Staphylococcus aureus infections are common, causing high mortality, compounded by the propensity of the bacterium to develop drug resistance. The bacteria often target the knees, shoulders, hips, and fingers or toes. hyicus is a known animal pathogen. One such enzyme, lipase, has been recognized for its relationship in the virulence of S. Microbes that were frequently recovered from the infection site with S. Staphylococcus epidermidis is a common member of the human epithelial microflora and one of the most frequent nosocomial pathogens. . haemolyticus [ 6 ]. Some of the important enzymes produced by Staphylococcus aureus include: 1. haemolyticus) constitutes the main part of the human skin microbiota. aureus is also a major human pathogen able to adapt to diverse hosts and environmental Staphylococcus aureus, a Gram-positive bacterium colonizing nares, skin, and the gastrointestinal tract, frequently invades the skin, soft tissues, and bloodstreams of humans. Signs and symptoms may include: Joint swelling. Apr 15, 2022 · This case demonstrated endocarditis in an immunocompetent man; underlying MAC may have been instrumental in the pathogenesis. Staphylococcus aureus is the most dangerous of all of the many common staphylococcal bacteria. Blood agar (BAP) is made with 5% sheep blood. [1] Ineffective treatment of S. It is typically considered to be a component of the normal flora of the skin. Alternatively, in the upper airway, viral infection damages mucosal linings and predisposes PATHOGENESIS. aureus and the different “approaches” of these two related bacteria to evade human immune defenses during colonization and infection. It has been associated with disordered patterns of immunological response and impaired epithelial barrier integrity. Polymorphonuclear leukocytes (neutro …. epidermidis in particular is the most frequently isolated species from human epithelia. More than a century after the first descriptions of Staphylococcus were written, we now understand it to be at the forefront of many disease processes, one of which is staphylococcal pneumonia Here, I will present molecular factors that are involved in the success of S. Owing to our insufficient understanding of its pathogenesis, the occurrence and outcome of endocarditis has not improved over the last decades. At that time, it was better recognized as a cause of sepsis and abscess formation. It usually presents 48 hours after birth and is rare in children older than six years. aureus) in acne vulgaris. Courtesy of Dr. We reviewed the nature of polymicrobial interactions between S. epidermidis uses to survive during infection are in general of a passive Jul 7, 2016 · Infection of foot ulcers is a common, often severe and costly complication in diabetes. Aug 2, 2023 · Staphylococcus xylosus is a commensal of murine skin, but can become pathogenic when there are disruptions to the skin barrier and/or when the host immune response is compromised. Mohamed M. It is a leading cause of bacteremia and infective endocarditis as well as osteoarticular, skin and soft tissue, pleuropulmonary, and device-related infections. Staphylococcus hyicus is a Gram-positive, facultatively anaerobic bacterium in the genus Staphylococcus. aureus (CA-MRSA), combined with the S. S aureus is a gram-positive, catalase-positive, coccoid bacteria that appears in grape-like clusters on stained smears. Previous. Staphylococcus aureus , a Gram-positive bacterium colonizing nares, skin, and the gastrointestinal tract, frequently invades the skin, soft tissues, and bloodstreams of humans. Broken skin, such as when there are scrapes or cuts, is often the site of a MRSA infection. aureus is an excellent case study of the S. Severe respiratory infection due to staphylococci has been increasing due to the prevalence of more virulent USA300 CA-MRSA strains in the general population. [5] Jul 16, 2021 · Pathogenesis in Staphylococcus aureus is a result of the expression of differ ent virulence. Staphylococcus aureus is a leading cause of human infections worldwide. It commonly leads to abscess formation. 5 S. Diabetic foot infections (DFI) are mainly polymicrobial, and Staphylococcus aureus is the most frequent pathogen isolated. 2: Staphylococcus aureus pathogenesis in osteomyelitis. Staphylococcus aureus employs a variety of pathogenic mechanisms during skeletal infection. Fever. These features predispose the patients to robust colonization of skin lesions by Staphylococcus aureus. The rising prevalence of community-acquired methicillin-resistant S. Like other CoNS, S. xylosus, and S. factors such as toxins, immunomodulators and exoenzymes [47]. Here, we show that C. Staphylococcus aureus causes many types of human infections and syndromes—most notably skin and soft tissue infections. Aug 2, 2017 · Introduction. S epidermidis has been identified as a major cause of nosocomial infections, especially in patients with predisposing factors such as indwelling or implanted foreign Sep 1, 2016 · Toxin production clearly contributes to the pathogenesis of Staphylococcus aureus, but that does not mean it is always in the best interest of the pathogen. Artificial joints may also be at risk of infection. aureus pneumonia, which classically presents a week after onset of influenza infection. xylosus infections. This chapter discusses the molecular biology and genome characteristics of S. Jan 1, 2008 · Abstract. Staphylococcus aureus is a virulent pathogen that is currently the most common cause of infections in hospitalized patients. It colonizes predominantly the axillae, head, and nares 5. Multilo Jul 17, 2023 · Staphylococcus aureus is a major bacterial human pathogen that causes a wide variety of clinical manifestations. It has emerged as an important nosocomial pathogen, especially in infections of indwelling medical devices. Apr 27, 2023 · Staphylococcus epidermidis is a coagulase-negative, gram-positive cocci bacteria that form clusters. epidermidis as a colonizer and pathogen, with a specific focus on the interaction with S. Toxin production clearly contributes to the pathogenesis of Staphylococcus aureus, but that does not mean it is always in the best interest of the pathogen. caprae has been implicated in a variety of human infections, with the highest incidence being in bone and joint infections Mar 24, 2022 · Staphylococcus aureus is a leading cause of bovine mastitis worldwide. aureus inoculation into an open wound. [1] S. In the case-control study, a total of 324 people were screened for nasal carriage Abstract. [2][3] S. Jan 1, 2018 · The opportunistic pathogen Staphylococcus aureus is a common colonizer of the human skin, but, once overcoming the skin barrier, it may cause a variety of pyogenic and systemic infections, acute and chronic infections, and toxin-mediated syndromes in both health care and community settings. S. Both bacterial and host factors are crucial for the outcomes of BSI and sepsis. Staphylococcus is a gram-positive coccus that mediates many toxin and adhesin factors [21, 22]. lugdunensis) is a coagulase-negative staphylococcus organism. At the same time, this pathogen is one of the leading causes of life-threatening bloodstream infections, such as sepsis and endocarditis. The secretion of coagulases, proteins that Aug 30, 2020 · These bacterial infections are usually caused by the coagulase-positive Staphylococcus aureus ( S. Jul 25, 2023 · Staphylococcal Scalded Skin Syndrome, also known as Ritter disease is a disease characterized by denudation of the skin caused by exotoxin producing strains of the Staphylococcus species, typically from a distant site. This pathogen can cause a wide variety of diseases, ranging from moderately severe skin infections to fatal pneumonia and sepsis. Mar 9, 2022 · Staphylococcus hominis is a Gram-positive coagulase-negative member of Staphylococci that exists as a commensal on the human body, especially in the areas with apocrine glands, axillae, and the pubic region. aureus forms a complex structure of extracellular polymeric biofilm that provides a fully secured and functional environment for the formation May 31, 2022 · Staphylococcus haemolyticus (S. Of these infections, those involving the cornea (keratitis) or the inner chambers of the eye (endophthalmitis) are the most threatening because of their potential to Mar 24, 2022 · Staphylococcus aureus is a leading cause of bovine mastitis worldwide. Of these infections, those involving the cornea (keratitis) or the inner chambers of the eye (endophthalmitis) are the most threatening because of their potential to cause a loss in visual acuity or even blindness. These gram-positive, sphere-shaped (coccal) bacteria (see figure ) often cause skin infections but can cause pneumonia, heart valve infections, and bone infections and may be resistant to treatment with some antibiotics. Staphylococcus aureus is a common human pathogen highly evolved as both a component of the commensal flora and as a major cause of invasive infection. Indeed, how bacteria are able to thrive in the turbulent environment of the heart remains elusive. Atopic dermatitis is a common, recurrent pruritic dermatosis with a complex pathogenesis. 2. A characteristic feature of S. aureus and other bacterial, fungal, and viral cocolonizers. For example, USA300 is a predominant community-associated methicillin Jan 31, 2021 · Staphylococcus aureus is one of the most frequent worldwide causes of morbidity and mortality due to an infectious agent. 9 Staphylococcus aureus, like many pathogenic bacteria, produces a variety of enzymes that contribute to its virulence and ability to cause infections. aureus infection can involve any organ system. aureus are Haemophilus influenzae Infections. Jul 31, 2023 · Streptococcus pyogenes is a major human-specific bacterial pathogen that causes a wide array of manifestations ranging from mild localized infections to life-threatening invasive infections. The term staphylococcus, generally used for all the species, refers to the cells’ habit of aggregating in grapelike clusters. In this review we will present the current understanding of the pathogenesis of these invasive May 3, 2024 · staphylococcus, (genus Staphylococcus ), group of spherical bacteria, the best-known species of which are universally present in great numbers on the mucous membranes and skin of humans and other warm-blooded animals. However, more recently, it has also been identified as a pathogen in a variety of infections, particularly in skin and soft tissue [ 1 ]. Abstract. aureus skin and soft tissue infections and are formed, in part, to contain the nidus of infection. Nov 11, 2019 · The role of infective agents in autoimmune diseases (ADs) development has been historically investigated, but in the last years has been strongly reconsidered due to the interest in the link between the microbiome and ADs. is also a Jul 16, 2021 · Staphylococcus aureus (also denoted as Staph. Abscesses are a frequent manifestation of S. 1 Staphylococcus aureus. Swollen. aureus) is a pathogen that has been published in the literature since the 1800s. Staphylococcus epidermidis is the most frequently encountered member of the coagulase-negative staphylococci on human epithelial surfaces. elegans organisms that are fed S. May 3, 2023 · Staphylococcus aureus is a common and dangerous bacterium that can cause various infections in humans. Issues related to clinical manifestations and treatment of CoNS infections are discussed separately. They are the most common coagulase-negative Staphylococcus species that live on the human skin. Together with the gut, the skin microbiome is characterized by the presence o … Jul 13, 2023 · Staphylococcus aureus is an important pathogen that leads to significant disease through multiple routes of infection. Each of . Staphylococcus aureus is an opportunistic pathogen that normally colonizes the human anterior nares. aureus is a formidable pathogen capable of causing infections in different sites of the body in a variety of vertebrate animals, including humans and livestock. Even with surgical and antibiotic therapy, bloodstream infections are associated with significant mortality. Most S. Pathogenic Staphylococci can produce a variety of virulence factors, including toxins,coagulase, leucocidins, and hydrolytic enzymes that can damage host tissues. [1] Many times, these coagulase-negative staph species Abstract. Staphylococcus aureus is an opportunistic pathogen and the major causative agent of numerous hospital- and community-acquired infections. Rarely, this commensal organism can become pathogenic in humans. Despite some improved understanding of disease pathogenesis, progress towards new methods for the control of intramammary infections (IMI) has been limited, particularly in the field of vaccination. Conserved Mechanisms of Two-Component Systems Apply to Quorum-Mediated Virulence Regulation in S. Aug 19, 2022 · These are Staphylococcus aureus, associated with infections of cattle, poultry, and rabbits, Staphylococcus hyicus, the main causative agent of greasy pig disease, and Staphylococcus pseudintermedius, the main causative agent of canine pyoderma. This is a valuable resource for researchers, clinicians, and students interested in staphylococcal infections. Septic arthritis is often caused by a staph infection. epidermidis is mostly involved with indwelling medical There is considerable evidence which suggests a possible pathogenetic role for Staphylococcus aureus (S. Since it has a lack of the virulence factor coagulase, this is known for being less pathogenic than S. It can cause various types of diseases, some of which are life-threatening, such as staphylococcal bacteremia, sepsis, and toxic shock syndrome [ ]. Dec 14, 2023 · Staphylococcus aureus is an important pathogen responsible for a broad range of clinical manifestations ranging from relatively benign skin infections to life-threatening conditions such as endocarditis and osteomyelitis. It is widespread in hospitals and among medical staff, resulting in being an emerging microbe causing nosocomial infections. Sep 23, 2021 · Staphylococcus aureus is a clinically important pathogen that causes a wide range of human infections, from minor skin infections to severe tissue infection and sepsis. aureus as a pathogen is the plethora of virulence factors that manipulate the host’s innate and adaptive immune responses. It causes disease in poultry, [2] cattle, [3] horses, [4] and pigs. aureus or S. Staphylococcus intermedius has been long regarded as the common cause of pyoderma in dogs and other animals. lugdunensis can cause severe disease reminiscent of the virulent infections frequently Nov 1, 2020 · Staphylococcus aureus. Staphylococcus is a genus of Gram-positive bacteria in the family Staphylococcaceae from the order Bacillales. aureus pathogenesis have been conserved, irrespective of the host, and that specific C. Staphylococcus species are facultative anaerobic organisms (capable of growth both aerobically and anaerobically). Sep 18, 2018 · Cytolytic pore-forming toxins including alpha hemolysin (Hla) and bicomponent leukotoxins play an important role in the pathogenesis of Staphylococcus aureus. elegans host factors can alter susceptibility to this gram-positive human pathogen. Recent advances in staphylococcal molecular biology have provided more detailed insight into the basis of biofilm formation in these opportunistic pathogens. Alternatively, in the upper airway, viral infection damages mucosal linings and predisposes the host to S. aureus colonization and antibiotic susceptibility patterns in patients with acne and of healthy people. Under the microscope, they appear spherical ( cocci ), and form in grape -like clusters. vp qy yj dg vt wu dj yw te ck