Osteomyelitis Flashcards
Methicillin-resistant Staphylococcus Aureus (MRSA)
Predisposing Factors:
Hospitals, prisons, nursing homes, close living quarters, military, athletes, weakened immune systems.
MRSA
Incubation period
Highly variable; typically 4-10 days, but asymptomatic (years)
Any strain of S. aureus that has developed multiple drug resistance(s) to _______________
beta-lactam antibiotics
CA-MRSA definition
Community-acquired MRSA seen in outpatient settings
HA-MRSA definition
Hospital-acquired MRSA, typically nosocomial
MSSA Definition
Any strain of S. aureus susceptible (abled to be killed by) beta-lactam antibiotics
What issue?
SSTIs, specifically furuncles, carbuncles, and abscesses, are the most
frequently reported clinical manifestations.
(a) Patient’s c/c of “spider bite”
(b) Areas of fluctuance and purulent drainage are commonly present
MRSA
What is the mainstay of therapy for any fluctuant lesion secondary to MRSA.
Incision & drainage (I&D)
I&D is followed by
proper packing of the wound, daily dressing changes, and oral antibiotics
What are the antibiotics used to treat a MRSA infection?
(a) TMP-SMX (160mg/800mg)
-1) PO bid x 5-10 days
(b) Clindamycin 300 – 600mg
-1) PO bid x 5-10 days
(c) Doxycycline 100mg
-1) PO bid x 10 days
MRSA – Disposition
Unless complications develop, most cases of MRSA should be
retained onboard and treated by the IDC.
What would these issues necessitate?
(a) SSTI on the face, neck, or head that may require I&D.
(b) Any case of orbital cellulitis, regardless of suspected etiology
(c) Any SSTI unresponsive after 48 hrs. to antibiotics therapy
with activity against MRSA.
(d) Any SSTI with suspicion of transition to osteomyelitis.
(e) Any Necrotizing Soft Tissue Infection consistent with
Necrotizing Fasciitis
An MO should be consulted
MRSA – Disposition
Patients with recurring infections should be
referred to a MO
-May be colonized with MRSA and require decolonization or referral to Dermatology.
What is the 3rd most common bite wound pattern after dog & cat bites?
Human bites
Human bites occur in two basic categories:
a) ____________________
-1) Similar to dog or cat bites; teeth closing over and
breaking the skin
b) _________________________
-1) Skin surface strikes a tooth resulting in damage to skin & underlying structures
(a) Occlusive wounds
(b) Clenched-fist or “fight bites”
Likelihood of infection secondary to human bite determined by depth
& location of wound:
(a) Approximately 2% for ______
(b) <10% for _______
(c) >25% for ____________ or _____________________
a) superficial wounds
b) occlusal bites
c) clenched-fist wounds or other wounds on the hand
What issue?
(1) MOI:
-(a) Often occurs secondary to moderate-to-high speed kinetic impact of clenched-fist with teeth of other individual.
-(b) Occur most commonly in adolescent boys and adult men
(2) Location:
-(a) Typically dorsal aspect of 3rd, 4th or 5th MCP joint
(3) Patho-anatomy:
-(a) Teeth lacerate overlying skin and penetrate capsule of MCP joint during kinetic impact
–i. Mouth flora (bacteria) enter joint.
–ii. Bacteria are trapped under extensor tendon and/or joint capsule as fist is released from clenched position
Clenched Fist Injury (Fight Bite)
Clenched Fist Injury (Fight Bite) Management
– No signs/symptoms of infection
Hand wounds are examined with fingers extended & in the _________ position; wounds can often ‘disappear’ with fingers in extension.
clenched fist
Clenched Fist Injury (Fight Bite) Management
What is the primary factor in preventing infection?
Initial wound care
Clenched Fist Injury (Fight Bite) Management
What is the primary factor in preventing infection?
Initial wound care
Initial wound care steps
(a) Control bleeding, clean wound with soap & water, povidone iodine, or CHX.
(b) Assess for tendon injury & assess neurovascular integrity.
(c) Local anesthesia, irrigation with sterile saline & removal of grossly visible debris.
(d) Careful re-examination of cleaned & anesthetized wound
(e) Determine whether wound closure is appropriate.
(f) Dress/bandage wound to prevent secondary infection or injury. Follow-up in 24hrs.
True/False
Human bites are considered tetanus-prone wounds
True
Clenched Fist Injury (Fight Bite)
Management – No signs/symptoms of infection
(1) Hand wounds are examined with fingers extended & in the clenched fist position
(2) Initial wound care
(3) Assessment of TDAP/HBV/HIV immunization/testing status.
(4) Evaluation for ABx prophylaxis & follow-up/re-evaluation Q24 hrs.
until healed,
True/false
Clinically uninfected bite wounds should not be cultured; results not
predictive of subsequent infection.
True
True/False
In general, human bite wounds can be closed due to the
high risk for the development of infection.
False
SHOULD NOT
Patients who undergo primary closure warrant what?
antibiotic prophylaxis.
What is the exception for closing a bite wound and why?
Facial lacerations where cosmesis is a concern
What bite wounds would warrant prophylactic abx?
(a) Lacerations undergoing partial closure and wounds requiring surgical repair.
(b) Wounds on the hand(s), face, or genital area.
(c) Wounds near a bone or joint.
(d) Wounds in areas of underlying venous and/or lymphatic compromise.
(e) Wounds in immunocompromised hosts (including diabetes).
(f) Wounds with associated crush injury.
Can you use these abx for hum bite wound prophylaxis?
1) Cephalexin (keflex)
2) Penicillinase-resistant penicillins PRPs (dicloxacillin)
3) Macrolides (erythromycin & azithromycin)
No
ABx without activity against Eikenella Corrodens should be avoided.
what is the proffered Prophylactic ABx for human bite wounds?
Amoxicillin clavulanate 875/125mg PO BID x 5 days
What issue
(1) History
-(a) High index of suspicion if involved in a physical altercation
-(b) Patient often unwilling to reveal Hx & may delay presentation until signs/symptoms are intolerable
(2) Symptoms
-(a) Progressive development of pain, edema, erythema, and
drainage over wound.
(3) Physical exam
-(a) Hand wounds are examined with fingers extended & in the clenched-fist position.
-(b) Often presents as a transverse, irregular wound over dorsal aspect of MCP joint
-(c) Typically involves 3rd/4th/5th MCPs, but can involve any digit
-(d) Erythema, warmth, and/or edema overlying wound & joint; ±
purulent drainage
-(e) Possible pain with passive ROM of MCP joint
-(f) Neurovascular status is often preserved
Infected bite wound
Hx of clenched fist injury warrants imaging to r/o what?
body and fracture
Human Bites – Disposition
Med Advice is warranted in what following circumstances?
(a) Clenched-fist wounds
(b) Complex facial lacerations
(c) Deep wounds, especially if significant avulsion or amputation present (likely Medevac)
(d) Wounds associated with neurovascular compromise (likely Medevac)
What issue?
(1) Organism Type: Spore-forming, anaerobic, gram-positive bacterium
(2) Scientific name: Clostridium tetani
(3) Common Name: lockjaw
Tetanus
Predisposing Factors for tetanus
Inadequate TD immunization
no TD booster within 10 years
puncture wound,
penetrating injury with retained foreign body,
untreated necrotic tissue,
crushing injuries
Tetanus Incubation Period:
3 to 21 days, usually about 8 days
True/False
The further the inoculation the site is from CNS the longer the incubation period for tetanus
True
Tetanus
(1) Vaccine Preventable: ___
(2) Reportable: ___
(3) Lethal: ____
(1) Vaccine Preventable: Yes
(2) Reportable: Yes
(3) Lethal: Yes
What issue?
An acute, often fatal, exotoxin-mediated disease produced by gram positive, spore-forming anaerobic rod, Clostridium tetani.
Tetanus
Tetanus Spores can survive autoclaving at ______°F for 10-15
minutes & are relatively resistant to phenol & other chemical agents.
249.8
_____________ conditions allow germination of spores and production of two exotoxins, collectively called ‘tetanus toxin.’
Anaerobic
What issue?
Commonly presents first in a descending pattern
(a) Typically the first sign is trismus or lockjaw, followed by nuchal rigidity, dysphagia, and rigidity of abdominal muscles.
(b) Muscle spasms may occur frequently (q10-15 min) and may last upwards of several minutes each episode.
(c) Other symptoms include hyperthermia, diaphoresis, hypertension, and episodic tachycardia
Common late symptoms are:
(a) Periods of apnea due to contraction of thoracic muscles or
pharyngeal muscle contraction.
(b) Fracture of long bones/ vertebrae during muscle spasms
(c) Nosocomial infections secondary to long-term
hospitalization, aspiration pneumonia
(d) Death typically occurs secondary to respiratory arrest
Tetanus
Tetanus – Treatment
If you suspect actual tetanus in a patient:
(a) Immediate transfer to nearest MTF (Urgent MedEvac)
(b) Clean/debride wounds as best as possible
(c) Supportive therapy and airway protection
Tetanus – Treatment
Antibiotics:
(a) Metronidazole 500mg IV Q6-8H for 7-10 days
(b) Pen G 2-4Mil Units IV Q4-6hrs (alternate)
(c) Tetanus Immune Globulin (TIG, HTIG):
How long is the recovery for tetanus
months to years
True/False
Prophylactic antibiotics are beneficial for tetanus after injury
False
They do not provide any benefit. However, observe wounds for
SSTIs from organisms other than tetanus.
Dirty wounds pose an increased risk for tetanus; clinicians should
consider wounds dirty if what?
Contaminated with dirt, soil, feces, or saliva (animal or human bites).
Dirty wounds pose an increased risk for tetanus; clinicians should
consider wounds dirty if what?
Contaminated with dirt, soil, feces, or saliva (animal or human bites).
True/False
Clinicians should clean all wounds, remove dirt or foreign material,
and remove or debride necrotic material.
True
Patients with completed 3-dose primary tetanus vaccination series
(a) Last documented dose of TDAP < 5 years earlier:
–1) _________________
(b) Last documented dose of TDAP was > 5 years ago:
–1) _________________
a) They do not require TDAP vaccine as part of wound management
b) Administer a booster dose of TDAP.
How can the bone can become
susceptible to disease?
-introduction of a large inoculum of bacteria,
-secondary to trauma,
ischemia,
-the presence of foreign bodies the bone
Among younger adults, OM occurs most commonly from what?
Trauma
Among older adults, OM occurs most commonly as a result of what?
contiguous spread of infection to bone from adjacent soft tissues and joints
(ie. diabetic foot wounds, decubitus ulcers)
Clinical diagnosis of OM requires what?
high index of suspicion, a good HPI/PE, and knowledge of common risk factors
In adults, OM most often affects what?
vertebrae of the spine and/or the hip
In OM extremities are frequently involved due to ____________________
skin wounds, trauma and surgeries
Risk factors for OM:
Bacteremia, endocarditis, IV drug use, trauma, and open fractures.
What issue?
(a) Acute issue typically presents with gradual onset of symptoms over several days.
(b) Patients present with dull pain at the involved site, with or
without movement.
-1) Local findings (tenderness, warmth, erythema, and swelling)
-2) Systemic symptoms (fever, rigors) may also be present.
-3) Patients with this issue involving the hip, vertebrae, or pelvis tend to manifest few signs or symptoms other than pain.
OM
_______ is an essential component in the evaluation of suspected OM
Radiographic imaging
Most useful Rad studies for OM are what?
plain radiographs, (MRI), and technetium-99 bone scintigraphy.
A plain radiograph typically initial imaging of choice but
may have a delay of about how many days before
appearance/findings suggestive of OM?
14 days
what are the most common causative agents of acute OM in adults and children
S. aureus (MSSA & MRSA strains)
What are the 2 pillars of OM Tx
surgical containment & prolonged ABx therapy
empiric ABx therapy for OM consists of what?
Vancomycin & IV Ceftriaxone
Surgical debridement of OM of all diseased bone is often required due to what?
poor antibiotic penetration.
