Infection of bones n joint Flashcards
3 bone and joint Infections
- Infectious Arthritis
- Osteomyelitis
- Infections with Prostheses of Bones and Joints
Clinical features of acute infection
•90% monoarticular
•60-80% fever-usually mild
•Knee most common site, then hip
•sternoclavicular-consider IVDA
•10% polyarticular-underlying RA
Clinical presentation acute
•JOINT EFFUSION
•JOINT CONTRACTURE
FLEXION
•PAINFUL MOTION
•TEMP 39-40 Celcius
Laboratory finding for bone and joints infections
• elevated ESR
• synovial fluid
– turbid
•–>50K WBC, 75%PMN’s,
– low glucose-bacterial, also RA,
crystaline disease
Laboratory findings
•Bacteriology
–joint fluid gram stain + 1/3
–joint fluid culture + >90%
–blood culture + 10-60%
–synovial tissue culture-mycobacteria,fungi
Etiology and causes of infections
most common:
Staphylococcus aureus
• adults <30 Gonococcal
• children - H. influenzae, Salmonella
• neonates, elderly, DM, Group B Streptococcus
• elderly,chronic disease,
•UTI Gram negative rods
• IVDA - P.aeruginosa, sternoclavicular joints
Etiology
•Bite
•human-oral strep, anaerobes
•cat,dog-Pasteurella
•rat-Streptobacilus moniliformisl
–Intermittent, migratory polyarthritis, knee
•Lyme (chronic), GC (faster)
•Chronic
•TB, atypical mycobacteria, fungi-spores, blasto, cocci,histo
What is gonococcal arthritis
Gonococcal arthritis-2 forms
•Disseminated
•–fever,chills
––skin lesions-papules/ petechiae/ pustules
––polyarticular with bacteremia.
––Organism in skin scrapings.
––Negative synovial culture
»Monoarticular
•More like routine bacterial, suppurative infection
•positive synovial culture, may have preceding history like disseminated form
Viral causes of arthritis
Viral Causes of arthritis
•Rubella
–Women, with rash
–Self limited, usually hands
–vaccine induces arthritis in 40% post pubertal women
•Hepatitis B
–up to 20%, symmetric
–early-resolves with onset jaundice
•Mumps
–onset with parotitis
•Parvovirus B19
–women, Erythema infectiosum
–Late winter, spring
–Arthropod borne
–Lymphocytic choriomeningitis virus
–severe flu-like ilness with headache
•HTLV-1
•HIV
Pathogenesis of infectious arthritis
•Usualy hematogenous
•Predisposing factors
•–pre-existing arthritis
•–trauma-interruption of capillary integrity
•–systemic diseases-malignancy, DM, immunosuppressive therapy
Definition osteomyelitis
•Osteomyelitis is a bone infection usually caused by bacteria, including mycobacteria, but is sometimes caused by fungi.
The original site of infection is elsewhere in the body,
and spreads to the bone by the blood.
Pathophysiology of osteomyelitis
- Hematogenous spread
Child- distal femur, proximal tibia
Adult- axial skeleton - Contigunous Spread
- In association with vascular insufficiency
What diagnosis of osteomyelitis ( Radiograph 1)
MRI of the lower extremities of a 45 year old man with several weeks of leg pain and low grade fever. An abscess cavity is evident
Dignosis of osteomyelitis , history and physical examination
History
- Presence if risk factor
- Symptoms of inflammation
Physical examination
- Signs of inflammation
-Decreased range of motion
- Drainage, sinus tract and ulceration
Etiology and causes of osteomyelitis
-Bacteria or fungal spores may infect the bone directly through open fractures, during bone surgery, or from contaminated objects that pierce the bone. Staphylococcus aureus is the bacteria most commonly responsible. Mycobacterium tuberculosis (the main cause of tuberculosis) can infect the vertebrae to cause osteomyelitis
Pathogenesis of infectious arthritis, osteomyelitis
-Usualy hematogenous
•Predisposing factors
•–pre-existing arthritis
•–trauma-interruption of capillary integrity
•–systemic diseases-malignancy, DM, immunosuppressive therapy
Investigations for osteomyelitis
Investigations
•Blood cultures
•Bone biopsy (which is then cultured)
•Bone scan
•Bone x-ray
•C-reactive protein (CRP)
•Erythrocyte sedimentation rate (ESR)
•MRI
•Needle aspiration of the area around affected bones
Laboratory Finding of Osteomyelitis
Laboratory Investigations
•Elevations in the erythrocyte sedimentation rate (ESR—a test that measures the rate at which red blood cells settle to the bottom of a test tube containing blood),
•elevated level of C-reactive protein (a protein that circulates in the blood and dramatically increases in level when there is inflammation usually occur.
• elevated levels of white blood cells.
•these blood tests are not sufficient to diagnose osteomyelitis.
Radiology Investigation osteomyelitis
Radiological Investigation
•An x-ray may show changes characteristic of osteomyelitis, but sometimes not until more than 3 weeks after the first symptoms occur.
• Computed tomography (CT) and magnetic resonance imaging (MRI) can also identify the infected area
-The infected area almost always appears abnormal on bone scans (images of bone made after injecting radioactive technetium),
-llustration of the results of an external wound that
destroys periosteum and allows bacteria to colonize the cortical bone surface. The medullary circulation
What antibiotics use for bone and joints infections
Antibiotics
•MSSA-oxacillin(+ rifampin)
•MRSA-Vancomycin(+ rifampin)
•Enterococcus-ampicillin/vancomycin, plus aminoglycoside for significant part of time
•Gram-(including GC & H Flu)-ceftriaxone/ cefotaxime/ ciprofloxacin
•Pseudomonas-ceftazidime(or pipercillin) + aminoglycoside/ quinolone