Osteomyelitis Flashcards
What causes Osteomyelitis
- Methicillin-resistant Staphylococcus aureus (MRSA)
- Human Bites
- Tetanus
Any strain of S. aureus that has developed multiple drug resistance(s) to beta-lactam antibiotics.
These antibiotics include methicillin and other more common antibiotics such as oxacillin, penicillin, and amoxicillin
MRSA
Any strain of S. aureus susceptible (abled to be killed by) beta-lactam antibiotics.
MSSA
Most common clinical manifestation of MRSA
SSTIs, specifically furuncles, carbuncles, and abscesses, are the most frequently reported clinical manifestations of MRSA.
Treatment of MRSA
Incision, drainage, & irrigation is the mainstay of therapy for any fluctuant lesion, followed by proper packing of the wound, daily dressing changes, and oral antibiotics.
Antibiotics for MRSA
- TMP-SMX (160mg/800mg) PO BID x 5-10 days
- Clindamycin 300 – 600mg PO BID x 5-10 days
- Doxycycline 100mg PO BID x 10 days
Disposition of MRSA
Unless complications develop, most cases of MRSA should be retained onboard.
3rd most common bite wound after dog and cat bites
Human bites
- Typically sustained when a clenched fist strikes the teeth of another person
- Highly prone to infection given the proximity of the skin over the knuckles to the joint capsule
Clenched fist injury
Location:
- Typically dorsal aspect of 3rd, 4th or 5th MCP joint
Patho-anatomy:
- Teeth lacerate overlying skin and penetrate capsule of MCP joint during kinetic impact
- Mouth flora (bacteria) enter joint
- Bacteria are trapped under extensor tendon and/or joint capsule as fist is released from clenched position
Clenched Fist Injury (Fight Bite)
Treatment of Clenched Fist Injury (Fight Bite)
- Initial wound care is the primary factor in preventing infection:
- Control bleeding, clean wound with soap & water, sterile saline, povidone iodine, or CHX.
- Let it bleed for minute or 2 unless its arterial, better to let the blood push it out since all of your interventions will be pushing in.
- Assess for foreign body, tendon injury (frequently missed), and neurovascular integrity.
- Human bite wounds should not be closed due to high risk of developing infection
- Consider antibiotics
- Dress/bandage to prevent secondary infection.
- Follow up in 24h for reassessment
Do Trivial human bites that do not break the skin or are very superficial require prophylaxis
No
When would a human bite warrant prophylactic
- Lacerations undergoing partial closure and wounds requiring surgical repair
- Wounds on the hand(s), face, or genital area
- Wounds near a bone or joint
- Wounds in areas of underlying venous and/or lymphatic compromise
- Wounds in immunocompromised hosts (including diabetes)
- Wounds with associated crush injury
Which medications should not be used for human bite prophylactic
- ABX without activity against E. corrodens should be avoided
Meaning you cannot use: - Cephalexin (keflex)
- PRPs (dicloxacillin)
- Macrolides (erythromycin & azithromycin)
What antibiotic should be used for human bites
Amoxicillin-clavulanate 875/125mg PO BID x 5 days
Deep infection of fight bite
- Pain with passive movement
- Pain out of proportion to exam
- Joint swelling
- Crepitus
- Systemic illness (fever and hemodynamic instability)
Antibiotics needed to cover S.aureus and streptococci
- Augmentin 875/125mg BID for 3-5 days
If penicillin allergy: - Doxycycline 100mg BID for 3-5 days PLUS
- Clindamycin 300mg TID for 3-5 days
Labs for fight bites
- Aerobic and anaerobic wound culture
- CBC
- ESR and CRP if concern for osteomyelitis
- Blood culture if there are signs of systemic illness
Rads for fight bite
- Hx of clench fist injury warrant imaging
- Rule out foreign body and fracture
When is MEDADVICE warranted for human bites
- Clenched-fist wounds
- Complex facial lacerations
- Deep wounds, especially if significant avulsion or amputation present (likely Medevac)
- Wounds associated with neurovascular compromise (likely Medevac)
- An acute or chronic inflammatory process involving bone & structures secondary to infection with pyogenic organisms, including bacteria, fungi, and mycobacteria.
Osteomyelitis
When would younger adults get osteomyelitis
trauma (penetrating injury i.e. stepping on nail) and related surgery
When would older adults get osteomyelitis
infection to bone from adjacent soft tissues and joints (ie. diabetic foot wounds, decubitus ulcers).
Osteomyelitis most affects which area in adults
- Affects the vertebrae of the spine and/or the hips.
- However, extremities are frequently involved due to skin wounds, trauma and surgeries.
- Patients present with dull pain at the involved site, with or without movement.
- Local findings (tenderness, warmth, erythema, and swelling)
- Systemic symptoms (fever, rigors) may also be present.
- involving the hip, vertebrae, or pelvis tend to manifest few signs or symptoms other than pain.
Osteomyelitis
Labs for osteomyelitis
CBC may have leukocytosis, blood cultures may be positive, erythrocyte sedimentation rate (ESR) elevation, C-reactive protein (CRP) elevation
What is an essential component in the evaluation of suspected osteomyelitis
- Plain radiographs, magnetic resonance imaging (MRI), and technetium-99 bone scintigraphy.
- A plain radiograph typically initial imaging of choice but may have a delay of about 14 days before appearance/findings suggestive of OM.
- Radiographs are often used to R/O other potential causes such as metastasis or osteoporotic fractures.
Treatment of osteomyelitis
- 2 pillars of OM Tx are surgical containment & prolonged ABx therapy
- Surgical Containment:
Surgical debridement of all diseased bone is often required due to poor antibiotic penetration - Prolonged antibiotic therapy cornerstone of treatment for OM
- Results of C&S should guide antibiotic treatment, however, empiric ABx therapy consists of IV Vancomycin & IV Ceftriaxone.
Disposition of osteomyelitis
Patient needs to be evacuated to higher level MTF
- Widely distributed in soil, and the intestines & feces of farm animals. In agricultural areas, a significant number of adults may harbor the organism.
- Bacterium itself is sensitive to heat & cannot survive in the presence of oxygen (obligate anaerobe), however, c. tetani spores are very heat-resistant & resistant to many of the most common antiseptics:
Tetanus
- Acute, often fatal, exotoxin-mediated disease produced by gram-positive, spore-forming anaerobic rod, Clostridium tetani.
Tetanus
What temperature can tetanus survive at for autoclaving
Spores can survive autoclaving at 249.8°F for 10-15 minutes & are relatively resistant to phenol & other chemical agents.
Tetanus toxin is what causes the symptoms of tetanus and is one of the most potent toxins known, how much to keel
Minimum lethal dose in humans is approximately 2.5 ng per kg.
227.5 nanograms of tetanus toxin drops (kills) a 200-pound man.
Commonly presents first in a descending pattern:
- Typically the first sign is trismus or lockjaw, sardonic smile, followed by nuchal rigidity, dysphagia, and rigidity of abdominal muscles.
- Muscle spasms may occur frequently (q10-15 min) and may last upwards of several minutes each episode.
- Other symptoms include hyperthermia, diaphoresis, hypertension, and episodic tachycardia
Tetanus
Common late symptoms are:
- Periods of apnea due to contraction of thoracic muscles or pharyngeal muscle contraction
- Fracture of long bones/ vertebrae during muscle spasms
- Nosocomial infections secondary to long-term hospitalization, aspiration pneumonia
- Death typically occurs secondary to respiratory arrest
Tetanus
Prevention of tetanus
- All Wounds are either considered:
Clean vs. contaminated/dirty - Superficial vs. deep/penetrating.
- Dirty wounds increased risk for tetanus; wounds are dirty if:
- Contaminated with dirt, soil, feces, or saliva (animal or human bites).
- Penetrating or puncture wounds = Potential risk for the development of tetanus.
- Wounds containing:
- Devitalized tissue (necrotic or gangrenous wounds), frostbite, crush injuries, avulsion fractures, and burns are particularly conducive for proliferation of C. tetani.
When should TDAP be given
- No documentation or questionable TDAP HX = NO TDAP.
- TDAP was > 5 years ago:
Treatment of tetanus
- Immediate transfer to nearest MTF (urgent MedEvac)
- Clean/debride wounds as best as possible
Supportive therapy and airway protection
Antibiotics: - Metronidazole 500mg IV Q6-8H for 7-10 days (preferred)
- Pen G 2-4Mil Units IV Q4-6hrs (alternate)
- Neutralization of unbound toxin:
- Tetanus Immune Globulin (TIG); Human Tetanus Immune Globulin (HTIG):
500 units IM at different sites from the Tetanus Toxoid, part of the dose should be infiltrated around the wound
How long is recovery for tetanus
Recovery after tetanus infection is notoriously prolonged (multiple months to a year in some cases).
