Infections of the Integumentary System Flashcards

Flashcards on Infections of the Integumentary System

Macules

Flat lesions characterized by change in color of the affected skin

Papules

Raised lesions, solid in consistency of less than 5mm in diameter

Plaques

Flat with elevated surface (plateau-like) with more than 5mm diameter

Nodules

Rounded raised lesions more than 5mm in diameter

Urticaria (Wheals of Hives)

Annular or ring-like papules or plaques with pinkish color

Vesicles

Circumscribed fluid-filled lesions less than 5mm in diameter

Bullae

Circumscribed fluid-filled lesions more than 5mm in diameter

Pustules

Circumscribed, exudate-filled lesion

Purpura - Petechiae

Skin lesions due to bleeding into the skin, less than 3mm diameter

Purpura - Ecchymosis

Skin lesions due to bleeding into the skin, greater than 3mm diameter

Ulcer

Crater-like lesion that may involve the deeper layers of the epidermis and dermis

Eschar

Necrotic ulcer covered with a blackened scab or crust

Staphylococcus aureus

A Gram-positive, spherical (coccoid) bacterium that commonly colonizes the skin and mucous membranes.

Mode of Transmission of Staphylococcus aureus

Transfer via direct contact, fomites, and autoinoculation

Clinical Findings of Staphylococcus aureus infection

Pimples, boils, carbuncles, abscesses, impetigo, cellulitis, folliculitis, and scalded skin syndrome

Complications of Staphylococcus aureus infection

Spread of infection to the bloodstream, abscess formation

Laboratory Diagnosis of Staphylococcus aureus

Microscopic examination showing Gram-positive cocci in clusters.

Treatment of Staphylococcus aureus

Antibiotics depend on susceptibility.

Prevention of Staphylococcus aureus

Good hand hygiene and wound care.

Staphylococcus epidermidis

Part of the normal flora of the skin and is commonly associated with “stitch abscess,” UTI, and endocarditis

Streptococcus pyogenes

A species of Gram-positive, aerotolerant bacteria belonging to the genus Streptococcus.

Mode of Transmission of Streptococcus pyogenes

Transmission can also occur through direct contact with infected skin lesions or contaminated objects (fomites).

Clinical Findings of Streptococcus pyogenes

Includes impetigo, cellulitis, erysipelas, and scarlet fever

Complications of Streptococcus pyogenes

Spread of infection to tonsils, sinuses, skin, blood, and middle ear.

Laboratory Diagnosis of Streptococcus pyogenes

Culture on blood agar showing beta-hemolysis

Treatment of Streptococcus pyogenes

Penicillin or cephalosporins are the first-line antibiotics.

Prevention Strategies for Streptococcus pyogenes

Preventing transmission by good respiratory hygiene

Pseudomonas aeruginosa

A Gram-negative, aerobic (and facultatively anaerobic), rod-shaped bacterium

Mode of Transmission of Pseudomonas aeruginosa

Transmission primarily occurs via contact with contaminated water, soil, or medical equipment.

Clinical Findings of Pseudomonas aeruginosa

Wound and burn infections. Otitis externa (swimmer’s ear). Folliculitis from hot tubs

Complications of Pseudomonas aeruginosa

Necrotizing soft tissue infections. Biofilm formation leads to persistent infections resistant to antibiotics and immune clearance.

Laboratory Diagnosis of Pseudomonas aeruginosa

Culture on selective media such as cetrimide agar producing characteristic blue-green pigment (pyocyanin).

Treatment of Pseudomonas aeruginosa

Antibiotics commonly used include: Antipseudomonal penicillins, Cephalosporins, Carbapenems, Fluoroquinolones, Aminoglycosides.

Prevention of Pseudomonas aeruginosa

Strict adherence to infection control practices in healthcare settings, including hand hygiene.

Clostridium perfringens

A Gram-positive, rod-shaped, anaerobic, spore-forming bacterium

Mode of Transmission of Clostridium perfringens

Spores enter deep wounds contaminated with soil or foreign material, leading to gas gangrene and tissue necrosis

Clinical Findings of Clostridium perfringens

Gas gangrene (clostridial myonecrosis)

Complications of Clostridium perfringens

Gas gangrene: Life-threatening; can cause shock, multi-organ failure, and death if untreated

Laboratory Diagnosis of Clostridium perfringens

Isolation and culture of C. perfringens from wound swabs or tissue samples; a characteristic double zone of hemolysis on blood agar may be observed

Treatment of Clostridium perfringens

Requires urgent surgical debridement of necrotic tissue, high-dose intravenous antibiotics (penicillin is the drug of choice), and supportive care

Prevention of Clostridium perfringens

Clean and debride wounds promptly, especially deep or contaminated wounds

Bacillus anthracis

A Gram-positive, rod-shaped, spore-forming bacterium that causes anthrax

Mode of Transmission of Bacillus anthracis

Through skin abrasions or wounds contaminated with spores

Clinical Findings of Bacillus anthracis

Begins as a painless, itchy papule that progresses to a characteristic black necrotic ulcer (eschar) with surrounding edema

Complications of Bacillus anthracis

Untreated anthrax can rapidly progress to systemic infection, septic shock, multi-organ failure, and death.

Laboratory Diagnosis of Bacillus anthracis

Microscopic examination and Gram stain showing large Gram-positive rods; Dorner stain or Wirtz-Conklin stain.

Treatment of Bacillus anthracis

First-line antibiotics include penicillin, ciprofloxacin, and doxycycline.

Prevention of Bacillus anthracis

Vaccination of at-risk populations such as military personnel and laboratory workers; animal vaccines are used in endemic areas.

Warts Causative Agent

Skin warts are caused by infection with certain strains of the human papillomavirus (HPV), a double-stranded DNA virus

Clinical Findings of Warts

Benign, rough, hyperkeratotic skin growths that can vary in size from 1 millimeter to several centimeters.

Laboratory Diagnosis of Warts

Diagnosis is primarily clinical, based on characteristic appearance.

Treatment of Warts

Topical agents: Salicylic acid, imiquimod, cantharidin.

Prevention of Warts

Avoid direct skin-to-skin contact with warts on others.

Herpes Simplex Causative Agent

Caused by the herpes simplex virus (HSV)

Clinical Findings of Herpes Simplex

Initial (primary) infection may cause painful, grouped vesicles on an erythematous base, which rupture to form ulcers.

Laboratory Diagnosis of Herpes Simplex

Polymerase chain reaction (PCR): Highly sensitive for detecting HSV DNA from lesions or bodily fluids.

Treatment of Herpes Simplex

Acyclovir, valacyclovir, famciclovir are commonly used.

Prevention of Herpes Simplex

Avoid direct contact with active lesions or secretions from infected individuals.

Measles (Rubeola) Etiologic Agent

Caused by the measles virus, a single-stranded, enveloped RNA virus belonging to the Morbillivirus genus within the Paramyxoviridae family

Mode of Transmission of Measles (Rubeola)

The virus spreads through respiratory droplets when an infected person coughs, sneezes, or breathes

Clinical Findings of Measles (Rubeola)

High fever (≥104°F), cough, coryza (runny nose), and conjunctivitis.

Complications of Measles (Rubeola)

Pneumonia (1 in 20 children), encephalitis (1 in 1,000), and hospitalization (1 in 5 unvaccinated individuals).

Laboratory Diagnosis of Measles (Rubeola)

Detection of measles-specific IgM antibodies in serum (collected 3–10 days post-rash).

Treatment of Measles (Rubeola)

Focuses on hydration, fever management, and monitoring for complications.

Prevention of Measles (Rubeola)

Two doses of MMR vaccine are 97% effective. Recommended at 12–15 months and 4–6 years.

Rubella (German Measles) Etiologic Agent

Classified as a single-stranded RNA virus from the Togaviridae family, genus Rubivirus

Mode of Transmission of Rubella (German Measles)

Person-to-person via respiratory droplets

Clinical Findings of Rubella (German Measles)

Includes low-grade fever, malaise, conjunctivitis, lymphadenopathy, and mild upper respiratory symptoms

Complications of Rubella (German Measles)

Deafness, cataracts, congenital heart disease, intellectual disability, growth retardation, and organ inflammation

Laboratory Diagnosis of Rubella (German Measles)

Detection of rubella-specific IgM antibodies (indicates recent infection) or a significant rise in IgG titers between acute and convalescent samples.

Treatment of Rubella (German Measles)

There is no specific antiviral therapy, management includes rest, fluids, and antipyretics

Prevention of Rubella (German Measles)

The MMR (measles, mumps, rubella) vaccine is highly effective and the primary preventive measure.

Roseola Infantum (Exanthem Subitum or Sixth Disease) Etiologic Agent

Primarily caused by human herpesvirus 6B (HHV-6B), with less common cases caused by human herpesvirus 7 (HHV-7)

Mode of Transmission of Roseola Infantum (Exanthem Subitum or Sixth Disease)

Occurs mainly through respiratory secretions such as saliva

Clinical Findings of Roseola Infantum (Exanthem Subitum or Sixth Disease)

Sudden onset of high fever (39.5–40.5°C) lasting 3 to 5 days without localizing symptoms.

Complications of Roseola Infantum (Exanthem Subitum or Sixth Disease)

Febrile seizures are the most common complication.

Laboratory Diagnosis of Roseola Infantum (Exanthem Subitum or Sixth Disease)

Diagnosis is primarily clinical based on characteristic fever and rash pattern in infants.

Treatment of Roseola Infantum (Exanthem Subitum or Sixth Disease)

No specific antiviral therapy is routinely recommended. Treatment is supportive and symptomatic

Prevention of Roseola Infantum (Exanthem Subitum or Sixth Disease)

Prevention relies on good hygiene practices to reduce transmission, such as handwashing

Erythema Infectiosum (Fifth Disease) Etiologic Agent

Caused by human parvovirus B19, a small, single-stranded DNA virus from the Parvoviridae family.

Mode of Transmission of Erythema Infectiosum (Fifth Disease)

Primarily spread via respiratory droplets from infected individuals during close contact

Clinical Findings of Erythema Infectiosum (Fifth Disease)

Characteristic “slapped cheek” rash: bright red erythema on the cheeks lasting 2–4 days.

Complications of Erythema Infectiosum (Fifth Disease)

Anemia or aplastic crisis, Blood transfusions or IVIG may be necessary

Laboratory Diagnosis of Erythema Infectiosum (Fifth Disease)

Serology: Detection of parvovirus B19-specific IgM antibodies indicates recent infection

Treatment of Erythema Infectiosum (Fifth Disease)

Generally self-limited and requires no specific antiviral therapy.Supportive care includes antipyretics and analgesics for fever and arthropathy.

Prevention of Erythema Infectiosum (Fifth Disease)

Prevention focuses on good respiratory hygiene

Monkeypox (Mpox) Causative Agent

Caused by the monkeypox virus (MPXV), a double-stranded DNA virus belonging to the Orthopoxvirus genus

Clinical Findings of Monkeypox (Mpox)

Fever, malaise, headache, sore throat, cough, muscle aches, back pain, chills, and swollen lymph nodes

Laboratory Diagnosis of Monkeypox (Mpox)

The gold standard test, performed on samples from skin lesions or bodily fluids to detect viral DNA

Treatment of Monkeypox (Mpox)

Supportive care: hydration, pain control, treatment of secondary infections

Prevention of Monkeypox (Mpox)

Avoid close contact with infected individuals or animals, especially contact with lesions or bodily fluids

Superficial Mycoses Definition

Fungal infections confined to the outermost layers of the skin, hair, and nails

Common Causative Organisms of Superficial Mycoses

Dermatophytes, Malassezia species, Piedra species

Clinical Manifestations of Pityriasis versicolor

Characterized by hypo- or hyperpigmented scaly patches

Diagnosis of Superficial Mycoses

Microscopic examination of skin scrapings, hair, or nail samples using KOH preparation to identify fungal elements

Treatment of Superficial Mycoses

Topical antifungals are effective for most superficial infections

Cutaneous Mycoses Definition

Fungal infections that affect keratinized tissues such as the skin, hair, and nails

Dermatophytoses

Caused by dermatophyte fungi from the genera Trichophyton, Microsporum, and Epidermophyton

Clinical Presentations of Dermatophytoses

Manifest as ringworm (tinea) infections including tinea capitis (scalp), tinea corporis (body), tinea pedis (athlete’s foot), tinea cruris (jock itch), and onychomycosis (nail infection)

Diagnosis of Cutaneous Mycoses

Direct microscopic examination of skin scrapings, hair, or nail clippings using potassium hydroxide (KOH) preparation to visualize fungal hyphae