Staphylococcus Aureus Infection Clinical Presentation

Updated: Jul 27, 2021
  • Author: Elizabeth P Baorto, MD, MPH; Chief Editor: Russell W Steele, MD  more...
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Skin and soft tissue (impetigo)

Typically, this starts as a small area of erythema that progresses into bullae (filled with cloudy fluid) that rupture and heal with the formation of a honey-colored crust. Although group A Streptococcus was once considered the primary agent, Staphylococcus aureus has become the major pathogen since the 1980s. [105] S aureus exclusively causes bullous impetigo, which is observed less frequently in the United States. This form of disease seems to arise from healthy-appearing skin. The bullae rupture, leaving a denuded area with a varnish-like coating.

Scalded skin syndrome (Ritter disease)

An exfoliative toxin (see Toxin-mediated disease) causes this relatively rare syndrome, which takes the form of superficial fragile blisters that burst, leaving a tender base. The patient is often febrile and, occasionally, has mucopurulent eye discharge. This diagnosis should be made carefully, because scalded skin syndrome may be mistaken for erythema multiforme or toxic epidermal necrolysis, which can be treated with corticosteroids. Misdiagnosis delays treatment and allows exfoliation to progress, and corticosteroid therapy may potentiate bacterial superinfection. Although the mortality rate is low in children with this entity, most fatalities are associated with delay in diagnosis.

Folliculitis, furuncle, and carbuncle

These are increasingly severe staphylococcal skin infections. Folliculitis is a tender pustule that involves the hair follicle. A furuncle involves both the skin and the subcutaneous tissues in areas with hair follicles, such as the neck, axillae, and buttocks. They are actually small abscesses characterized by exuding purulent material from a single opening. A carbuncle is an aggregate of connected furuncles and has several pustular openings. Skin infections may be self-limited, but they can also disseminate hematogenously and cause life-threatening septicemia. [106, 107]

Bone infections (osteomyelitis)

Children often present with sudden onset of fever and bony tenderness or a limp. The pain may be throbbing and severe; however, presentation in neonates can be subtle. Infants may appear well except for failure to move an extremity or pain on movement. Redness or swelling indicates that infection has spread into the subperiosteal space. Rupture of a focus of osteomyelitis into joint space can result in septic arthritis. This is often observed in neonates.

Children with vertebral osteomyelitis present with back pain, and those younger than 3 years present with refusal to walk or with a limp. Occasionally, children with vertebral osteomyelitis present with incontinence. Children with discitis tend to present with less fever and often appear less ill than children with vertebral osteomyelitis.

Septic arthritis

Typical findings include decreased range of motion, warmth, erythema, and tenderness of the joint with constitutional symptoms and fever. Infants (in whom the hip is the most commonly involved joint) are an exception, as these signs may be absent. The child typically lies with the involved joint abducted and externally rotated. Because pain fibers are located within the joint capsule, movements that compress the head of the femur into the acetabulum (eg, changing a diaper) cause pain. A portal of infection is almost never found, and the infection is nearly always unilateral. Patients with infection of the sacroiliac joint present with tenderness elicited during digital rectal examination and with pain during flexion, abduction, and external rotation of the hip.


The initial presentation of patients with S aureus endocarditis is fever and malaise. However, the disease has a more rapid onset than that caused by less virulent pathogens. Notably, on initial presentation, the usual physical stigmata are absent. Endocarditis may also involve healthy valves. For more detail, please see Pediatric Bacterial Endocarditis.

Toxic shock syndrome (TSS)

Staphylococcal TSS is a potentially life-threatening systemic bacterial intoxication. Case definition includes fever, diffuse macular erythema, and hypotension, with involvement of 3 or more organ systems.

Emesis or diarrhea appears at the time of illness. Diarrhea is secretory and profuse, and is found in almost all patients with TSS but is uncommon in patients in septic shock.

Severe myalgia or elevated creatine kinase (CK) levels are observed. Myalgia may be one of the earliest manifestations of the disease.

Elevation of BUN or creatinine levels or more than 5 WBCs per high-power field in the absence of a urinary tract infection is observed.

Hepatic levels of bilirubin, serum glutamic-oxaloacetic transaminase (aspartate aminotransferase), and serum glutamic-pyruvic transaminase (alanine aminotransferase) are twice the upper limit of the reference range.

The platelet count is less than 100,000/μL.

Features include disorientation and alteration in consciousness with the absence of focal neurologic signs when fever and hypotension are absent.

A probable case of TSS involves 5 of the above 6 findings. A confirmed case of TSS involves all 6 findings.

The most striking aspect of the disease is the rapidity with which it can progress in a previously healthy individual of any age. This is especially true in postsurgical patients, particularly following nasal surgery, because this is an area commonly colonized with S aureus. Late-onset dermatologic findings include a red and pruritic maculopapular rash, desquamation of the fingers and toes, and telogen effluvium (see Toxic Shock Syndrome).


Cases of rapidly progressive and fatal staphylococcal pneumonia still occur, although they were much more common in the 1950s and early 1960s, when S aureus phage type 80/81 caused frequent disease in infants. Staphylococcal pneumonia most commonly occurs in infants, young children, and patients who are debilitated. This is a rapidly progressive disease. Patients with primary staphylococcal pneumonia present with a short prodrome of fever followed by rapid onset of respiratory distress, which may include tachypnea, retractions, and cyanosis. Patients may also have prominent GI tract symptoms. Staphylococcal pneumonia may also develop after influenza infection, which seems to occur preferentially among young adults (in whom mortality reaches 50%). Typically, the child seems to recover from a febrile illness only to once again develop an increasing fever and the symptoms mentioned above. In the CA-MRSA era, staphylococcal pneumonia is becoming more prevalent. [108]


Usually occurring in a hospitalized patient, thrombophlebitis is characterized by fever, pain, and, occasionally, erythema at the insertion site of an intravenous catheter. Occasionally, pus is expressed. Severe suppurative thrombophlebitis may occur in burn patients, with fewer than half of diagnoses made while the patients are alive.

Deep tissue abscess and infection

Muscles (myositis and pyomyositis) [109, 1, 2, 3] and organs can become infected, including the parotid gland, eyes, liver, spleen, kidneys, and central nervous system. [4] Deep abscesses also may occur. [5] These infections typically cause fever with or without localizing pain.



Skin and soft tissue (impetigo)

The infection initially appears as a small area of erythema. Bullae (ie, blister-like lesions filled with cloudy fluid) appear as the disease progresses. As bullae heal, a honey-colored crust develops.

Scalded skin syndrome (Ritter disease)

Examination reveals superficial, fragile blisters that burst, leaving a tender base. Skin sloughs easily when touched, a condition termed the Nikolsky sign. Fever is often present, and mucopurulent eye discharge may be observed. As discussed above, the infection is often mistaken for erythema multiforme or toxic epidermal necrolysis. Misdiagnosis must be avoided.

Folliculitis, furuncle, and carbuncle

Folliculitis is the appearance of a tender pustule involving a hair follicle. A furuncle is an apparent small abscess that exudes purulent material from a single opening. A carbuncle is an aggregate of furuncles with several openings. Blistering distal dactylitis is a superficial infection of the pad of the distal digit. [110]

Bone infections (osteomyelitis)

Fever, bony tenderness, or a limp indicates bone infections. Infants may appear well except for failure to move an extremity or pain on movement. Children with vertebral osteomyelitis present with back pain, and those younger than 3 years present with refusal to walk or with a limp. Occasionally, children with vertebral osteomyelitis have incontinence as a presenting symptom. Children with discitis tend to present with less fever and often appear less ill than children with vertebral osteomyelitis.

Septic arthritis

Examination reveals warmth, erythema, and tenderness of the joint. Constitutional symptoms and fever are frequently observed. These findings may be absent in an infant. Children with infection of the sacroiliac joint present with tenderness elicited during digital rectal examination.


The clinical syndrome widely varies and may involve multiple organs. S aureus infection usually results in an acute course but may involve subacute disease. Most patients present with high fever. Chills and sweats and a new or worsened murmur may occur. Peripheral emboli such as Osler nodes, subungual hemorrhages, Janeway lesions, and Roth spots may be present. Other embolic phenomena may occur.


TSS involves a fever of 38.9°C or higher. Hypotension occurs, either with blood pressure below the fifth percentile for age or with an orthostatic (lying to sitting) drop in diastolic blood pressure greater than or equal to 15 mm Hg. A diffuse, erythroderma-like rash is present. Conjunctival or vaginal hyperemia may be present. Patients may have altered sensorium, even when normotensive, or may be delirious, disoriented, or agitated without focal signs. Reddened lips and tongue may be observed. Later, on recovery, desquamation of hands and feet may occur; occasionally, alopecia occurs later.


Fever is present. Findings of respiratory distress include tachypnea, cyanosis, grunting, and retractions. Vomiting and abdominal distension occur. Clinical deterioration is rapid.


Patients usually have a fever and, occasionally, have cutaneous involvement such as erythema, induration, or tenderness. Occasionally, pus is expressed at the insertion site of the catheter. The exit site often does not show signs of infection. Establishing infection of an intravascular device as the cause of fever in a hospitalized patient is a diagnosis of exclusion.

Deep tissue abscess and infection

Localizing tenderness may be present, as may signs of inflammation.



Skin and soft tissue (impetigo)

Often occurring in young children, impetigo is spread within families and through close physical contact. Impetigo is more prevalent in warm, humid climates because of more opportunities for insect bites and cutaneous trauma. Impetigo may also be a complication of varicella. Diagnosis is usually made based on the characteristic appearance of the lesions. Bullous impetigo may also occur in endemic and epidemic patterns. Nursery outbreaks have been described, and some cases in infants have progressed to scalded skin syndrome or Ritter disease (described in History).

Folliculitis, furuncle, and carbuncle

Recurrent staphylococcal skin infections develop in certain patients, such as those with impaired neutrophil function (eg, those with chronic granulomatous disease), patients with atopy and chronic eczema, and those with impaired circulation and diabetes mellitus. However, most patients with recurrent furunculosis are colonized with CA-MRSA but are otherwise healthy. Thus, an evaluation of the immune system in these individuals is seldom useful.

Bone and joint infections (osteomyelitis)

Osteomyelitis typically occurs in children prior to the age of epiphyseal closure. Osteomyelitis typically originates in the metaphysis of long bones in the region of most rapid growth. Osteomyelitis usually involves (in order of frequency) the lower end of the femur, the upper end of the tibia and humerus, and the radius. Most bone and joint infections result from hematogenous spread, but significant blunt trauma is a preceding event in approximately one third of cases. In addition, penetrating wounds, compound fractures, and orthopedic appliances may introduce microbial infection directly into bone. Notably, the male-to-female ratio of skeletal infections is 2:1, mostly because boys are more likely to experience traumatic events.

Septic arthritis

Staphylococci are frequent etiologic agents of septic arthritis and, since the era of successful vaccination for Haemophilus influenzae, are now more predominant in younger age groups. The USA300 genotype is the most common clone in staphylococcal septic arthritis in children. [111] Bacteria can enter the joint space through hematogenous spread, direct inoculation, or contiguous spread of infection. Because the synovial membrane has a high effective blood flow, a large number of bacteria may be delivered to the joint during a period of bacteremia. Inoculation can occur when a joint is punctured with a contaminated object, and many clinical studies reveal that the knee is more likely to be punctured. In the postantibiotic era, contiguous spread has been rare, with the exception of neonatal osteomyelitis.


Fortunately, S aureus endocarditis is rare in pediatric patients. It often involves adolescent intravenous drug users who do not have antecedent valvular disease. These patients usually present with right-sided disease with evidence of pulmonary disease, such as pulmonary abscesses or shifting infiltrates. In children with preexisting heart disease, endocarditis is often temporally related to cardiac surgery or catheterization. Children with prosthetic valves are particularly vulnerable because of the organism’s propensity to adhere to foreign materials. In addition, patients with indwelling vascular access devices are at risk, because infections from the skin can seed the catheter, resulting in catheter-related blood stream infection and its consequences. [112]


Infection with toxin-producing S aureus in the absence of protective antibody is an antecedent. Younger patients may be at increased risk because they lack the protective antibodies to the enterotoxins and other exotoxins responsible for producing this clinical syndrome. However, other factors may be involved; Jacobsen et al demonstrated in a small study that not all patients without antibody develop true TSS when infected with a toxin-producing strain of the organism. [113]

The erythroderma of TSS depends on preexisting T-cell hypersensitivity and the toxin superantigen for amplification. [114]

Approximately 25% of all S aureus strains are toxigenic, and, at any time, roughly 4-10% of healthy individuals are colonized with these strains. In the 1980s, the disease was associated with the use of highly absorbent tampons in women during menstruation. Currently, many cases observed are nonmenstrual (eg, localized infections, surgery, infected varicella lesions, insect bites), and these now account for one third of all cases. These patients carry a higher mortality rate than those with menstrual TSS.


The primary form occurs without an extrapulmonary focus, presumably through direct inoculation to the lungs, and the secondary form results from hematogenous seeding of the lungs during endocarditis or bacteremia. Predisposing factors include infancy, chronic illness, and viral respiratory disease such as influenza. Patients with head injury and trauma who have nasopharyngeal carriage of S aureus are at increased risk of S aureus pneumonia.


The causes are associated with infusion, including infected intravenous catheters and needles. The common point of entry for infection related to intravascular devices is the insertion site along the outside of the device.

Deep tissue abscess and infection

These typically result from hematogenous seeding, although myositis or pyomyositis can result from contiguous spread of infection and endophthalmitis can follow trauma (injury or iatrogenic), for example.

Differential diagnosis

The differential diagnoses of staphylococcal infections include the following:

  • Impetigo - None

  • Bullous impetigo

    • Pemphigus

    • Pemphigoid

    • Burn

    • Stevens-Johnson syndrome

    • Dermatitis herpetiformis

  • Scalded skin syndrome (Ritter disease)

    • Nonaccidental injury

    • Scalding

    • Abrasion trauma

    • Sunburn

    • Erythema multiforme

    • Toxic epidermal necrolysis

  • Bone and joint infections

    • Bone infarction (in patients with sickle cell disease)

    • Toxic synovitis

    • Leukemia

  • Septic arthritis

    • Trauma

    • Deep cellulitis

    • Henoch-Schönlein purpura

    • Slipped capital femoral epiphysis

    • Legg-Calve-Perthes disease

    • Leukemia

    • Toxic synovitis

    • Metabolic diseases affecting joints (Ochronosis)

  • Endocarditis - Bacteremia

  • TSS

    • Staphylococcal scalded skin syndrome

    • Meningococcemia

    • Rubeola

    • Adenoviral infections

    • Dengue fever

    • Severe allergic drug reactions