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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