Lecture 2 - Infectious Disorders of the Orbit/Adnexa

What infectious disorders of the orbit/adnexa are covered in this lecture?

Impetigo, Erysipelas, Necrotizing Fasciitis, Orbital Cellulitis, Orbital Mucormycosis, Acute Dacryoadenitis, Acute Dacryocystitis, and Canaliculitis

What is a macule?

A small flat area less than 5 mm in size

What is a patch?

A macule larger than 5 mm

What is a plaque?

A solid elevated lesion that spreads across the skin surface

What is telangiectasia?

Dilated superficial blood vessels

What is a papule?

A small raised lesion less than 5 mm in size

What is a vesicle?

A small elevated blister less than 5 mm that usually contains clear fluid

What is a bulla?

A large vesicle

What are petechiae?

Ruptured capillaries due to prolonged stress that appear as lesions less than 2 mm on the skin or mucous membranes

What is ecchymosis?

A flat bruise larger than 1 cm caused by rupture of a blood vessel with subcutaneous blood spread

What is a hematoma?

A collection of mostly clotted blood caused by rupture of a large blood vessel

What is a papilloma?

A benign sessile or pedunculated lesion that may be single (nonviral) or multiple (viral)

What is erythema?

Redness

What is a pustule?

A focal infected raised accumulation of pus

What is a nodule?

A larger papule

What is an abscess?

A large pustule

What does the Latin root "impetere" mean?

To attack

What does the suffix "-igo" mean?

Disease state

What is impetigo?

A highly contagious bacterial epidermal infection of the face and extremities

What organisms commonly cause impetigo?

Streptococcus pyogenes (GABHS) and Staphylococcus aureus, including MRSA

What does GABHS stand for?

Group A beta-hemolytic streptococcus

Who is most commonly affected by impetigo?

Children and young adults

What is the most common skin infection in children?

Impetigo

What environmental conditions increase the risk of impetigo?

Warm, humid environments

What symptoms are associated with impetigo?

Pruritus, weeping skin lesions, and possible constitutional symptoms such as fever, diarrhea, weakness, and malaise

Is pain common in impetigo?

No, pain is very rare and the lesions usually look worse than they feel

What events may precede impetigo?

Insect bites, lacerations, abrasions, or infections such as varicella

Can impetigo occur as a secondary infection to chickenpox?

Yes

What are the three types of impetigo?

Non-bullous impetigo, bullous impetigo, and ecthyma (deep impetigo)

What is non-bullous impetigo?

The most common form of impetigo that progresses from an erythematous macule to a vesicle or pustule that ruptures

What characteristic crust is seen in non-bullous impetigo?

A honey-colored crust formed by dried serous exudate

How does non-bullous impetigo spread?

By contagious extension or inoculation from scratching

Is regional lymphadenopathy common in non-bullous impetigo?

Yes

Where is non-bullous impetigo located histologically?

In the epidermis and superficial dermis

What is bullous impetigo?

A form of impetigo characterized by fragile superficial bullae

What are collarettes in bullous impetigo?

Remnants of ruptured bullae consisting of raw skin surrounded by dead skin

What findings characterize bullous impetigo?

Fragile bullae, minimal surrounding erythema, clear or yellow fluid, and absence of regional lymphadenopathy

Where is bullous impetigo located histologically?

In the epidermis and superficial dermis

What is ecthyma?

The deep and most severe form of impetigo

Which type of impetigo is least common but most severe?

Ecthyma

How does ecthyma initially present?

Similar to non-bullous impetigo

How do ecthyma crusts differ from those of ordinary impetigo?

They are thicker, harder, and gray-yellow

What is seen when ecthyma crusts are removed?

Indurated ulcers extending into the dermis

Who is most commonly affected by ecthyma?

Children, elderly patients, and immunocompromised patients

Is regional lymphadenopathy common in ecthyma?

Yes

Where is ecthyma located histologically?

In deeper dermal tissue

How is impetigo managed locally?

Gentle cleansing, removal of crusts, antibacterial washes, and wet dressings

What antibiotic class is first-line therapy for impetigo?

Beta-lactam antibiotics such as penicillins and cephalosporins

What antibiotic is specifically listed as first-line treatment for impetigo?

Keflex

What antibiotics are recommended when MRSA is suspected in impetigo?

Trimethoprim-sulfamethoxazole (Bactrim) or clindamycin

What topical antibiotics may be used for impetigo?

Mupirocin (Bactroban) or retapamulin (Altabax)

When may hospitalization be required for impetigo?

Severe bullous impetigo or ecthyma

Why may hospitalization be necessary for severe impetigo?

To provide contact isolation and prevent dehydration or sepsis; IV antibiotics may be necessary

What does the Greek root "erysi-" mean?

Red

What does the Greek root "pella" mean?

Skin

What is erysipelas?

A rapidly advancing bacterial skin infection of the upper dermis that extends into the cutaneous lymphatics

What is another name for erysipelas?

St. Anthony's Fire

What body areas are commonly affected by erysipelas?

The legs and face

What organisms commonly cause erysipelas?

Streptococcus species (especially Streptococcus pyogenes/GABHS), Klebsiella pneumoniae, Haemophilus influenzae, and Moraxella

What is the most common cause of erysipelas?

Streptococcus pyogenes

What age group is most commonly affected by erysipelas?

Adults 60-80 years old

What systemic conditions are associated with erysipelas?

Diabetes, alcohol abuse, HIV infection, nephrotic syndrome, and a vagrant lifestyle

What historical findings may precede erysipelas?

Recent trauma, pharyngitis, malaise, chills, and high fever

What symptoms are associated with erysipelas?

Burning, pruritus, and local tenderness

What are the characteristic signs of erysipelas?

A fiery-red, indurated, tense, shiny plaque with raised sharply demarcated advancing margins

What severe skin findings may occur in erysipelas?

Vesicles, bullae, and skin necrosis

How is erysipelas treated?

Wet dressings and penicillin therapy for 10-20 days

What is the first-line antibiotic treatment for erysipelas?

Penicillin

When should patients with erysipelas be hospitalized?

In severe cases and in infants, elderly patients, or immunocompromised patients

What specialist referral should be considered for erysipelas?

Infectious disease

What does the Greek root "necro-" mean?

Dead or corpse

What does the Latin root "fasci-" mean?

Connective tissue

What is necrotizing fasciitis?

A rapidly progressive soft tissue infection characterized by widespread fascial necrosis

What is another name for necrotizing fasciitis?

Flesh-eating bacteria syndrome

What organisms commonly cause necrotizing fasciitis?

Streptococcus pyogenes and Staphylococcus aureus acting alone or together

What tissues are destroyed in necrotizing fasciitis?

Skin, fat, and muscle fascia

What systemic complication is characteristic of necrotizing fasciitis?

Septicemia with systemic toxicity

What risk factors are associated with necrotizing fasciitis?

Insect bites, burns, lacerations, ocean water exposure, contaminated seafood exposure, intestinal surgery, diabetes, cancer, hepatic disease, renal disease, herpes zoster, and systemic steroid use

What is the hallmark symptom of necrotizing fasciitis?

Intense pain that may be out of proportion to physical findings

What happens to pain as necrotizing fasciitis progresses?

It eventually progresses to local anesthesia

What signs are associated with necrotizing fasciitis?

Edema extending beyond erythema, vesicles, crepitus, tissue necrosis, putrid discharge, bullae, gas production, and rapid spread through fascial planes

What is crepitus?

A crackling sensation caused by air trapped within tissue

Why can necrotizing fasciitis be difficult to recognize initially?

Classical inflammatory signs may be absent

How is necrotizing fasciitis classified medically?

A surgical emergency

How is necrotizing fasciitis treated?

Immediate hospitalization, surgical debridement, high-dose systemic antibiotics, hyperbaric oxygen, and IV immunoglobulin

What antibiotic regimen is listed for necrotizing fasciitis?

Penicillin G plus an aminoglycoside plus clindamycin

When may amputation be necessary in necrotizing fasciitis?

If a limb or organ is extensively involved

What is the mortality rate of necrotizing fasciitis?

Up to 25%

What is the mortality rate if sepsis develops in necrotizing fasciitis?

Approximately 70%

What is the 4th layer of the eyelid?

The orbital septum

What does the orbital septum separate?

The eyelid from the orbital contents

What is cellulitis?

Diffuse subcutaneous inflammation of connective tissue secondary to infection

What is orbital cellulitis?

An acute infection of orbital tissues posterior to the orbital septum

What conditions commonly cause orbital cellulitis?

Hordeolum, preseptal cellulitis, paranasal sinus infection, dental infection, insect bite, surgery, trauma, or immunocompromise

What organisms commonly cause orbital cellulitis?

Children: Haemophilus influenzae; Adults: Staphylococcus aureus and Streptococcus pneumoniae

Why is orbital cellulitis dangerous?

The infection can spread to the brain and can compromise extraocular muscles and the optic nerve

Who is most commonly affected by orbital cellulitis?

Children and young adults

Is orbital cellulitis usually unilateral or bilateral?

Usually unilateral

What symptoms are associated with orbital cellulitis?

Pain, redness, headache or tooth pain, nasal congestion/discharge, decreased vision, and diplopia

What signs are associated with orbital cellulitis?

Eyelid swelling and hyperemia, conjunctival swelling and hyperemia, proptosis, ocular misalignment, ophthalmoplegia, possible RAPD, fever, and malaise