What Is STSS (Streptococcal Toxic Shock Syndrome)?

Introduction

STSS (streptococcal toxic shock syndrome) is a severe disease linked with non-invasive or invasive group A streptococcal (Streptococcus pyogenes) infection. The infection may occur at any location but is mainly connected with infection of cutaneous lesions.

What Is the Etiology?

The causative organism for STSS is Streptococcus pyogenes or Group A Streptococcus. Streptococcus pyogenes are Gram-positive cocci that grow in chains. These bacteria show complete hemolysis (beta hemolysis) when grown on blood agar plates.

There exist more than eighty serologically different types of S. pyogenes, these can result in a wide range of diseases ranging from mild ones like pharyngitis (inflammation of the pharynx, commonly called sore throat) to severe infections like STSS and septicemia (a life-threatening condition in which bloodstream is infected with bacteria).

Any S. pyogenes infection can progress to STSS. The bacterium enters the body through a compromised barrier (like a skin injury) or the mucous membrane. From the point of entry, the bacterium then reaches the deeper tissues and, from there, enters the bloodstream.

The main sites of invasion are:

• Mucosa.

• Vagina.

• Larynx.

• Soft tissue.

The entry route has yet to be discovered in about half of the cases. Transmission occurs by direct contact with secretions from infected persons. Secondary cases among healthcare professionals and close contacts have been reported rarely. The incubation period varies depending on the site of entry. After the appearance of initial symptoms, hypotension develops within a day or two.

What Are the Risk Factors?

The risk factors include:

• Chronic Illness - Chronic illnesses like diabetes and alcohol use disorder increase the risk of developing STSS.

• Age - STSS is more prevalent in individuals above 65 years of age.

• Skin Breakdown or Injury - Individuals who have recently undergone surgery, skin injury, viral infections that cause open sores like varicella infection, etc, have increased risk.

What Are the Initial Symptoms?

The initial symptoms are flu-like symptoms and include:

• Nausea.

• Vomiting.

• Fever.

• Muscle pain.

• Chills.

These symptoms then rapidly progress to sepsis with hypotension (low blood pressure), rapid breathing (tachypnea), increased heart rate (tachycardia), and organ failure. The following organs are affected:

• Lung.

• Kidney.

• Liver.

• Blood.

What Is the Clinical Case Definition?

The clinical case definition for STSS is:

A disease associated with non-invasive or invasive group A Streptococcal infection with the following clinical manifestations:

• Hypotension:

The systolic blood pressure is equal to or lower than 90 mm of Hg for adults. For children less than 16 years, systolic blood pressure is lower than the 5th percentile by age of the child.

• Multi-organ Involvement:

Involvement of multiple organs characterized by 2 or more of the following:

• Renal Impairment - Creatinine level is equal to or greater than 2 mg/dL for adults. In individuals with pre-existing renal conditions, greater than twofold increase from baseline.

• Liver Involvement - Aspartate aminotransferase, alanine aminotransferase, or total bilirubin level is equal to or greater than twice the upper limit of baseline for the patient’s age. In individuals with pre-existing liver conditions, greater than twofold increase from baseline.

• Coagulopathy - Platelet count is equal to less than one lakh per millimeter cube of blood, or intravascular coagulation characterized by low fibrinogen level, presence of fibrin degradation products, and increased clotting time.

• Acute Respiratory Distress Syndrome - Characterized by sudden onset hypoxemia (low blood oxygen levels) and diffuse pulmonary infiltrates in the absence of cardiac failure.

• Rash - Generalized erythematous macular (red flat skin lesions) rash that desquamate.

• Necrosis - Soft tissue necrosis (cell death) like necrotizing fasciitis (a rare and serious bacterial infection that affects tissues and fascia), myositis, or gangrene (localized tissue death due to prolonged disruption of blood supply to the region).

How Is the Condition Diagnosed?

Blood culture gives positive results for S. pyogenes in more than half of the cases. Culture results from the site of infection are mostly positive and remain positive for many days, even after initiation of anti-microbial therapy.

Case classification:

• Probable - a probable case fulfills the clinical case definition for STSS without an identified cause for the illness and isolation of group A Streptococcus from a non-sterile location.

• Confirmed - a confirmed case fulfills the clinical case definition for STSS, isolating group A Streptococcus from an otherwise sterile location.

How Is the Condition Treated?

Treatment requires hospitalization. Due to the rapidly progressive nature of the condition and the fatality associated, early disease recognition is important. Penicillin is effective in treating infections; clindamycin may also be administered in cases that do not respond to Penicillin. Patient progress is analyzed frequently. In case of deep infections, surgical debridement may be needed. Fluid resuscitation and supportive care are also provided. Intravenous immunoglobulins are administered in the case of severely ill individuals.

What Are the Infection Control Measures That Are Taken?

The infection control measures to prevent patient-to-personnel transmission are:

• Proper adherence to standard precautions.

• Adherence to transmission precautions.

• Personnel should properly wash hands after patient contact.

• Use personnel protective equipment like gloves, gowns, etc, when handling harmful secretions, infective materials, etc.

The infection control measures to prevent personnel-to-patient transmission are:

• Disease transmission mostly occurs through droplet spread or direct contact. The transmission mostly occurs through carries in the delivery or operating room.

• Personnel with GAS (group A Streptococcal) infections should be restricted from patient care activities until a day after receiving proper therapy.

The infection control measures to be taken in preschools and daycare centers are:

• The most important measure in controlling infection is proper identification and management of infection.

• Kids with GAS infection should not return to preschools and daycare centers until at least a day after beginning antimicrobial therapy.

What Are the Complications?

STSS results in complications like organs shutting down and the body entering into shock (a life-threatening condition that occurs due to insufficient blood flow); complications include:

• Surgical removal of limb.

• Surgical removal of infected tissues can result in severe scarring.

• STSS is a deadly condition; out of 10 people affected, 3 can die due to infection even after treatment.

Conclusion

STSS is a severe bacterial infection that starts with “flu-like” symptoms and then rapidly progresses to serious complications like shock and multiple organ failures. Even after aggressive treatment, the mortality rate of the condition ranges from 30 to 70 percent. The mortality rate is lower in kids. Treatment requires hospitalization along with antimicrobial therapy, supportive care, and fluid resuscitation. Taking proper infection control measures reduces disease transmission.