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Acute bacterial skin and skin structure infections Market (ABSSSIs) are common types of skin infections caused by bacteria. These infections primarily involve the superficial layers of the skin, subcutaneous tissue, and sometimes deeper soft tissues. Two of the most common ABSSSIs encountered in clinical practice are cellulitis and wound infections.
Causes
ABSSSIs are usually caused by skin commensal bacteria such as Staphylococcus aureus and Streptococcus pyogenes. These bacteria naturally exist on the skin and in the nose without causing any harm. However, break in the skin either due to injury, cut, burn or surgery provides opportunity for these bacteria to enter deeper tissues and cause infection. Other less common causes of ABSSSIs include gram-negative bacteria like Pseudomonas aeruginosa. Risk factors predisposing to ABSSSIs include diabetes, obesity, smoking, intravenous drug use etc.
Manifestations
The clinical manifestations of ABSSSIs depend on the pathogen involved and the specific site of infection. Cellulitis usually presents as an area of spreading erythema, warmth, tenderness and swelling extending beyond the visible skin defect. Fever and chills may occur. Wound infections typically manifest as increased pain, swelling, purulent drainage and failure of the wound to heal as expected. Necrotizing fasciitis is a severe type of ABSSSI characterized by rapid progressive necrosis of fascia and soft tissues.
Diagnosis
The diagnosis of ABSSSI is usually made based on clinical examination findings along with relevant medical history. Blood tests like complete blood count may reveal leukocytosis. Pus or fluid aspirated from the affected site can be sent for microbiological evaluation to identify the causative organism. Imaging like ultrasonography helps to assess the extent and severity of soft tissue infections like necrotizing fasciitis. Blood cultures are indicated if systemic symptoms like fever, chills are present.
Treatment
Most ABSSSIs can be treated with antibiotic therapy alone without requiring surgical intervention. Choice of antibiotic depends on the suspected pathogen, its antibiotic susceptibility pattern and severity of infection. For suspected MSSA or streptococcal infections, first-line agents include cephalexin, dicloxicillin or clindamycin. For MRSA, doxycycline, trimethoprim-sulfamethoxazole, linezolid, vancomycin are some of the recommended agents. Severe infections and those caused by Pseudomonas require IV antibiotics along with surgical debridement.
Complications
Untreated or inappropriately treated ABSSSIs can lead to various complications like extensive skin and soft tissue necrosis as seen in necrotizing fasciitis or myositis. Secondary infection of deeper fascial planes or muscle compartments may occur. Spread of infection to bloodstream (bacteremia), lungs (pneumonia), heart (endocarditis) or joints (septic arthritis) can ensue leading to life threatening situations. Other complications include chronic non-healing wounds, contractures, Amputations and long term disfigurement may develop in severe cases.
Prevention
Some measures that help prevent ABSSSIs include good hygiene, proper care of wounds and injuries, wearing protective gloves/clothing during risky activities, vaccination against S. aureus for high risk patients etc. Care of indwelling medical devices and regular screening of hospitalized patients also helps prevent skin and soft tissue infections in health care settings. Prompt treatment of existing infections lessens the chance of complications and spread.
Cellulitis
Cellulitis is one of the most common clinical manifestations of ABSSSIs. It involves diffuse superficial infection and inflammation of the dermis and subcutaneous tissues. The most frequently isolated pathogen is Staphylococcus aureus followed by Streptococcus pyogenes and other gram-positive/negative bacteria.
Risk factors for developing cellulitis include skin breaks, venous insufficiency, obesity, diabetes, prior episodes of cellulitis etc. The typical presentation is of acute-onset erythema, warmth and pain spreading from a skin lesion or area of trauma. Systemic symptoms like fever and chills may accompany severe infection. Differential diagnosis includes erysipelas, deep venous thrombosis, panniculitis, etc.
Emergency treatment involves hospital admission, intravenous antibiotics and fluid resuscitation if indicated. First-line antibiotics consist of antistaphylococcal penicillins or cephalosporins with coverage against beta-hemolytic streptococci as well. Inpatient treatment is guided by response and continued till clinical signs and symptoms resolve fully followed by a suitable oral course to complete therapy. Preventive measures include management of predisposing conditions, surgical debridement of infected ulcers or abscesses. Recurrences, if any, usually respond to longer antibiotic courses. Prognosis is excellent with prompt diagnosis and appropriate treatment.
Wound Infections
Surgical site, traumatic and diabetic foot wound infections constitute the bulk of postsurgical/posttraumatic ABSSSIs. The infecting pathogens are often patient’s endogenous skin flora mainly comprising S. aureus and streptococci. Gram-negative organisms are common in severe and chronic lesions. Biofilm production by the organisms within wounds aids evasion of host immune response and antimicrobial resistance.
The diagnosis is based on clinical findings of worsening pain, erythema, swelling, purulent drainage and delayed healing at the wound site. Wound sampling and microbial culture help identify the offending pathogen/s. Systemic inflammatory signs depend on extent and depth of infection. Treatment consists of surgical debridement to remove necrotic and infected tissues. Appropriate empirical antibiotics are initiated till culture and sensitivity report guides definitive therapy. Factors like wound size, site, presence of necrosis or systemic toxicity determine need for inpatient management. Effective management helps achieve complete wound healing and prevents long term sequelae.
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1. Source: Coherent Market Insights, Public sources, Desk research
2. We have leveraged AI tools to mine information and compile it
