Chapter 12: Infection- Dr



Chapter 12: Infection- Dr. Kuhn

Non-Suppurative Infections Suppurative Infections

- Blastomycosis - Brodies’s Abscess

- Coccidioidomycosis - Septic Arthritis

- Maduromycosis - Suppurative Osteomyelitis

- Syphilis

- Tuberculosis

Non-Suppurative Infections

Blastomycosis

Background

• AKA- Gilchrist Disease

• It is produced by the fungus Blastomyces Dermatitidis. This fungus is inhaled by patients into the lungs and causes--- Pneumonitis and asymptomatic Bone Lesion

• Hematogenous transport is the likely means by which infection is disseminated to the skin & osseous structures

• It is endemic to the central & Great lakes regions and the Ohio & MS River Valley

• African –Americans & Native Americans are more common affected

• Men are affected more than women; Ratio 4:1- 15:1

• Infection often develop in people who have contact with:

o Soil, Those Who Work Outside or engage in outdoor activities

Imaging Finding

• Bone is the 3rd most commonly infected site after the pulmonary system and skin

• Bones most commonly affected are:

o Vertebral Bodies, Skull and Ribs

• Features Include:

o Eccentric well-circumscribed lesions

o Punch- Out Lesion occasionally

o Infection may spread along the ALL and skip the Vertebral Level—Also seen in TB

• The Knee is the most commonly infected followed by the:

o Ankle, Elbow, Wrist, and Hand

• Radiographic localization followed by biopsy and culture are the most accurate methods of diagnosis

• Neither Ultrasound, MRI, or Bone Scan can Properly diagnosis Blastomycosis

Clinical Comments

• Signs and Symptoms of Blastomycosis

o Joint and Muscle Pain Chest Pain

o Productive Cough Pleuritic Pain

• Silver Methenamine is used to detect the fungus

o Pt treated for Disease----23% mortality Rate

o Pt untreated for Disease-----80% mortality Rate

Coccidioidomycosis

Background

• AKA—Valley Fever & Desert Rheumatism

• It is a systemic infection caused by the soil fungus---Coccidioides immitis

• It is endemic to the SW of the USA, San Joaquin Valley, and Central & South America

• The Lungs are the primary site of infection by Inhalation

• Patients at risk are:

o People older than 65 and AIDS patients

• Increased risk are seen in:

o Blacks Mexicans

o Pregnant Woman Children younger than 5 yrs

o Adults older than 50 yrs

• When the disease spreads, it most commonly affects

o the skin subcutaneous tissues

o Mediastinum Skeletal System

Imagining Findings

• The Axial Skeletal is a common place for infection with the---Ankle & Knee are the more frequently affected

• Early Signs--- Decreased Joint Space & areas of localized osteopenia

• End Signs of Infection—Ankylosis

• Bone Scan typically can detect the infection in the early stages. These technique should be followed by MRI & CT

• Septic Arthritis

o Is secondary to coccidioidomycosis and usually seen as:

▪ Synovittis w/ Joint Effusion Periarticular Bone Destruction

Clinical Comments

• 1/3 develops symptoms that usually include a self-limiting pneumonitis caused by the inhaled air-borne spores

• Signs & Symptoms of coccidioidomycosis

o Fatigue Fever

o Coughing Night Sweats

• Performing a tissue biopsy and staining biologic samples with Silver Methenamine are diagnostic methods

Maduromycosis (Mycetoma or Eumycetoma)

Background

• Maduromycosis is the most common fungal infection worldwide

• It predominantly affects the Feet, which are infected by a penetrating trauma

• This disease s usually found in the tropic and normally isolated in soil and on thrones.

• Organism Responsible---- Petriellidum Boydii

• Maduromycosis is more common in:

o Mexico South America

o Guatemala

Maduromycosis cont.

Imaging Finding

• Painless Soft tissue swelling & mass are seen in all cases and is a early finding

Clinical Comments

• General Signs and Symptoms

o Multiple crusted nodules surrounded by Hyper pigmented tissue

o Common Triad

▪ Sinus Track

▪ Granules (colonies)

▪ Nodular enlargements of infected body parts

• Disease is almost painless

• The first sign typically is a small bump; the foot then becomes swollen but not painful.

• The affected limb becomes deformed as a result of microbial colonies

• When the disease breaks into the bone in much later stages, it is usually painless

• Treatment consists of antimicrobial agents & amputation.

Syphilis

Background

• Is a chronic systemic infection caused by Treponema pallidum

• Two categories: (1) Congenital and (2) Acquired

• Congenital

o Contracted by transplacental exposure of the fetus to the infection

o Two Types

▪ Early Congenital – Diagnosed in children younger than 2 y.o.a

▪ Late Congenital- Diagnosed in children 2 y.o.a & older

• Acquired

o Contracted by close physical contact with an infected individuals skin lesions or mucous membranes

o Three Types

▪ Primary – Chancre with local lymphadenopathy

▪ Secondary- Systemic Disorders

▪ Tertiary- Gumma formation; Rubbery, soft, destructive lesions

Imagining Findings

• Early Congenital Syphilis

o Early manifestations of Congenital syphilis include:

▪ Osteochondritis

▪ Periostitis

▪ Diaphyseal Osteitis

o Bones involved:

▪ Long Bones Small Tubular Bones

▪ Pelvis Vertebrae

o Metaphyseal abnormalities are seen in more than 90% of infants with symptomatic congenital syphilis

o The Most Common Radiographic Finding

▪ Lucent Metaphyseal Bands

o Wimberger’s Sign

▪ Is the destructive metaphysitis is particularly common along the medial margin of the proximal tibia.

• Late Congenital Syphilis

o Late manifestation of congenital syphilis include Destruction of & Periostitis in the:

▪ Tibia Nose

▪ Skull Maxilla

▪ Jaw Other Superficial Osseous Structures

o These changes are noted in patient in their late teens or early twenties

o Periostitis is most pronounced along the anterior surface of the tibia bilaterally creating a Saber Shin Deformity

o Clutton’s Joints- refer to the joints that undergo this type of destruction.

• Acquired Syphillis

o Radiographic finding are mostly confined to the Tertiary stage of Acquired Syphilis

o Changes mimic those of Late Congenital Syphilis

Clinical Comments

• Congenital Syphilis

o This should be suspected in any newborn whose mother had Positive Serologic evidence of syphilis

o Chronic Signs & Symptoms

▪ Anemia Hepatosplenomegly

▪ Rhinitis Skin Lesions

▪ Low Birth Weight

o Microhemagglunation tests are fundamental to diagnosis

Tuberculosis

Background

• Caused by Mycobacterium tuberculosis, bovis and/or africanum

• Spreads almost exclusively by human to human air borne transmission

• The Lungs are the primary target

• Largest increase of TB has been among Hispanic & African Americans

• Increased incidence are seen in HIV patients

• Skeletal TB

o Slightly more common in Females than Males

o It develops secondary to hematogenous spread of pulmonary infection

Tuberculosis Cont.

Imaging Finding

• Plain film is the best initial imaging for detecting TB often confined to one location

• In Long bones, it begins in the epiphysis and results in a secondary infection of the trabeculae

• The lung lesion is located in the Upper or apical regions

• The spine is affected 50% of cases and the hip & knee 15%

• Phemister Triad- suggest Arthritis

o Juxta-articular Osteoporosis

o Peripherally located osseous erosions

o Gradually Narrowing joint space

• In the Spine

o The anterior portion of the vertebral body is the most commonly affected region

o The most common spinal joint affected is the IVD

• Gibbous Formation

o Is a TB osteomyolitis in the thoracics of T/L Junction the produce a angular kyphosis of 113 degrees

• Subligament spread of TB produces----Scalloping of the Vertebral bodies

• Clinical Comments

o The most remarkable clinical feature of TB can be its lack of symptoms

o Symptoms not specific include;

▪ Anorexia Weight Loss

▪ Night Sweats Afternoon Fever

Suppurative Infection

Brodies’ Abscess

Background

• AKA- Cystic Ostomyelitis is a distinct presentation of sub acute or chronic osteolyelitis.

• Staphylococcus organisms are the most common cause of infection.

• Most affected patients are younger than 25 years than 25 y.o.a., and males are slightly more likely than females to become infected

Imaging Finding

• Plain film radiographic evidence of a Brodie’s abscess consists of a geographic region of osteopenia surrounded by a rim of sclerosis, with lesions that re typically slightly eccentric, metadiaphyseal, and is located in intramedullary bone

• The femur and Tibia are the bones most commonly involved.

Clinical Comments

• Pain in the most common complaint associated with a Brodie’s abscess

• The pain is persistent, but it may increase and decrease in severity and often worsen at night.

• Progressive nocturnal pain that may waken patients are classic features of a Brodie’s abscess

• Aspirin may dramatically relieve the pain, making it more difficult to differentiate an osteoid osteoma form a Brodies Abscess.

• Angiography can be used to confidently distinguish a Brodies Abscess form an osteoid osteoma.

o Osteiod osteomas demonstrate an opaque vascular blush that is not associated with a Brodie’s Abscess

• The classic treatment for a Brodie’s abscess is aseptic drainage, curettae, and administration of systemic antibiotics.

Septic Arthritis

Back Ground

• Is joint infection that is transmitted directly through surgery or trauma, through spread, or most commonly through hematogenous dissemination.

• Septic Arthritis causes joint damage and disability with the:

o Knee Hip Shoulder and Wrist being the most common site.

o Usually one joint is only involved

• Septic Arthritis tends to affect young children and elderly individuals.

• Most Common causative agent----- Staphylococcus aureus

Imaging Finding

• Early Signs

o Distension of the joint capsule

o Soft tissue swelling

o Osteopenia

• Late Signs

o Permeative or moth eaten bone destruction

o Loss of joint space

o Joint derangement

o Bony Ankylosis

Clinical Comments

• Joint infection typically cause

o pain and tenderness,

o loss of function,

o possibly a fever

• Conservative management entails-----Antibiotic therapy

Suppurative Osteomyelitis

Background

• Osteomyelitis is an infection of bone and bone marrow that is usually is caused by bacteria but also can be caused by fungi and other microbes

• Most Common causative agent----- Staphylococcus aureus

• Osteomyelitis tends to affect long bone, particularly those in the lower extremities

• In children,

o hematogenous osteomyelitis usually is located in the metaphyseal region of the long bone with the most commonly affected bones being the femur and tibia

• In Neonates and Adults

o The epiphysis is more commonly involved

• Diabetes mellitus is more commonly associated with osteomyelitis in the lower extremities

• Osteomyelitis is spread by three major routes:

o Hematogenous

▪ Infection of joint or long bones usually are a result of hematogenous spread, with the common primary sources including

• Urinary Tract Infections

• Pneumonia

• Skin abscesses

o Direct-

▪ The two most common types of trauma that produces osteomylitis are:

• Trauma-Open Fracture

• Surgery- surgical Bone reconstruction

o Contiguous

Imaging Finding

• One of the earliest signs of osteomyelitis

o Is deep soft- tissue swelling.

o Distortion or obliteration of fat planes and subcutaneous edema may be evident after the infection

o Focal osteopenia within the medullary cavity typically occurs first, followed by cortical destruction in a focal or multifocal presentation.

• During the middle stage of osteomyelitis,

o a cortical breach develops and leads to perostitis after infection

o Ischemic necrosis hastens the damage and results in pockets of dead bone called-----Sequestra

• In the Late Stages of Osteomyelitis

o The remaining Sequestra my surrounded by a florid periosteal reaction called an------Involucrum

o An opening in the involucrum is called a ------Cloaca. This may connect to a sinus and allow migration of pus and bloody bone debris onto the skin surface

• The bone and joint structures of some young children heal after infection, whereas older patients usually have residual deformities.

• A rare complication of osteomyelitis that can develop in later stages is a Marjolin ulcer-cloaca and sinus tract tissue that has developed into a squamous cell carcinoma

• The latent period for carcinoma development may be as long as 20 to 30 years.

Clinical Comments

• The classical clinical features of hematogenous suppurative osteomyelitis are:

o Chills

o Fever

o Malaise

o Local Pain

o Swelling

• Loss of function or decreased ROM in the affected region often develops

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