Download Chapter 104 Cecil notes

Chapter 104 Cecil’s
Acute arthritis
 Usually caused by septic arthritis which is usually caused by joint trauma leading to the
disruption of capillaries during unrecognized and transient bacteremia aloowing bacteria to spill
into the joint fluid resulting in the initiation of infection
 Microbiology:
o staph aureus-most common cause
o pseudomonas aeruginosa-important cause amongst drug users
o other gram negative bacilli-common amongst elderly
o Neisseria gonorrhoeae-adults younger than 30 years
o Viral-hep B, rubella, mumps, parvovirus
 Clinical presentation
o Fever, joint swelling; May be difficult to see if patient has rheumatoid arthritis and on
corticosteroids
 Differential diagnosis of acute monoarticular or oligoarticular arthritis
o Radiographs- pseudogout
o Synovial fluid-cultured
o Gram stain prep and wet mound
 Check for crystals
 Synovial fluid leukocytes greater than 100000/uL suggests either infection or
crystal induced disease
o Blood culture if septic arthritis suspected
 Treatment
o Drainage-needle aspiration to remove fluid
o Antibiotics
 Staphylococcal-vancomycin, linezolid or daptomycin; penicillase-resistant
penicillin used for sensitive strains
 Gonococcal infection-ceftriaxone
 Gram negative rods-aminoglycoside or quinolone (ciprofloxacin) and
cephalosporin or piperacillin for P. aeruginosa
 S. aureus and gram negative bacilli-treated for 4-6weeks versus other bacteria
2-3 weeks is fine
Polyarticular arthritis
 Involves multiple joints and usually involves an immunologically mediated process
 Acute rheumatic fever-delayed immune mediated response to group A streptococcal infection,
asymmetrical arthritis of the joints
 Anti-strepotolysin O, anti-DNAse, and antihyaluronidase antibodies are usually present
Chronic arthritis
 Mycobacteria and fungi may produce slowly progressing incluing only one joint or contiguous
joints such as arm and hand
 Cultures of fluid may be negative
 Fungal arthritis should be treated with debridement and drainage with antifungal agents
 Spirochete, Borrelia burgdorferi- Lyme disease; tick bite; rash of erythema chronicum
migransarthritis with large effusions involving one or more joints; treat with ceftriaxone halts
progression of disease and treatment with amoxicillin or doxycycline will prevent later
development
Septic Bursitis
 S. aureus and involves olecranon or prepatellar bursa
 Needle aspiration to find out which bacteria
Osteomyelitis
 Hematogenous osteomyelitiso Infection occurs most commonly in the long bones or vertebral bodies
o Factors predisposing:
 S. aureus and pseudomonas aeruginosa-injection drug users
 S. aureus, Staph epidermidis, Candida species- intravenous catheters
 Enterobacteriaceae-U.T.I
o History of trauma like septic
o Range of motion is preserved in osteomyelitis as opposed to in septic arthritis
o MRI-used in diagnosis
 Bone erosion with decreased signal intensity on T1-weighted images
 Bone erosion with increased signal intensity on T2
 Erythrocyte sedimentation rate is high
o Spinal cord involvement if bowel or bladder strength weird
o Blood cultures
 If causative agent not identified: consider mycobacterial infection
 If ordinary bacterial infection still remains, treat with vancomycin for MRSA
o Treatment: acute spinal abscess surgery
o Diagnosis needed before neurological symptoms show up
Osteomyelitis secondary to extension of local infection
 Staph aureus and aerobic gram-negative bacilli-surgery and trauma
 Cat or dog bites-pasteurella multocida
 Human bite-mixed anaerobic
 Periodontal infections-mixed anaerobic
 Cutaneous ulcers-mixed anaerobic and aerobic
 Debridement and antibiotics
 Look for: ulcer, ESR: more than 70mm/hr and abnormal plain radiographdiabetes neg MRI
with all these others negativeprobably not osteomyelitis
Chronic osteomyelitis
 Untreated osteomyelitis results in avascular necrosis of the bone and formation of islands
known as sequestra
 Intermittent episodes od increased loca pain and drainage of infected material through sinus
tract
 Diagnosis: fluorodeoxyglucose positron emission tomography
 S. Aureus most commonly responsible
 Sickle cell patients-samonella most common cause
 Mycobacterium tuberculosis-affects anterior portion of vertebral bodies (paravertebral abscess
may complicate this infection because lacks signs)
 Diagnosis-histologic examination and culture of biopsy material