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Файл:Ординатура / Хирургия / Библиотека им академика М.И. Перельмана / Книга_3063_Библиотеки_им_академика_М_И_Перельмана
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However, most patients with MRSA have none of these risk factors.
Remember that for severe, invasive infections requiring inpatient therapy with IV antibiotics,
the drug of choice is vancomycin, but daptomycin, ceftaroline, tigecycline, telavancin, and
linezolid can also be used.
CLINICAL PEARL
Cellulitis with abscess formation or purulent drainage is most likely MRSA!
In the last few years there has been a dramatic increase in skin and soft-tissue (and
other site) infections due to community-acquired strains of MRSA. These strains are so
called, because as opposed to hospital-associated isolates of MRSA, patients with
CA-MRSA infection are relatively young and healthy and have had no recent contact
with the health care system.
Surgical drainage, along with incision of abscess and deeper infection, is crucial for adequate
treatment. A small abscess with no surrounding erythema needs no antibiotics.
In addition to incision and drainage, antibiotics are needed for the following:
Patients who are very young or elderly
Cases where multiple sites of infection, systemic illness, comorbidities, or
immunosuppression are present
Cases where infection quickly progresses and is associated with concomitant cellulitis
There is poor response to incision and drainage
Abscesses that are in locations where they are difficult to drain
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Final Diagnosis
Cellulitis
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Case 3
Chief Complaint
Right leg pain
History and Physical Examination
A 45-year-old woman presents to the emergency department with 2 days of severe right
lower extremity pain and swelling. The pain has been getting progressively worse and is
now so intense that she cannot walk on her leg. The pain started over the shin and has now
spread rapidly from the ankle to just below the knee. She is currently in extreme pain. She
also complains of fevers. She has a past medical history of diabetes type 2 and is non-
compliant. The diabetes is poorly controlled and her last Hb A1C about 1 year ago was
10%.
Physical examination reveals T 103° F, pulse 120/min, and BP 100/50 mm Hg. She is
diaphoretic, lethargic, and toxic-appearing. The lungs are clear. Cardiac exam is normal
except for tachycardia. Her right lower extremity shows tense edema with erythema and
dark purple bullae expanding from the ankle to the knee. Warmth and tenderness are noted.
Differential Diagnosis
Cellulitis1.
Deep venous thrombosis2.
Necrotizing fasciitis3.
43
Clues
Initial Management
Setting: emergency department
Diagnostic/Therapeutic Plan
Test Results
History and physical exam findings are very concerning for necrotizing fasciitis.
Extreme pain and tense edema with dark bullae with fevers and systemic toxicity on
examination are very worrisome for necrotizing fasciitis.
CBC
Chemistry profile
Lactic acid
Immediate surgical debridement (consult surgery); if there is clinical suspicion and the
physical exam is consistent with diagnosis, okay to send patient to the operating room
without imaging
Broad spectrum IV antibiotics
WBC 30,000 cells/mL
Segments 90%
Hb 10 mg/dL
Platelets 100,000
Lactate 8.2 mmol/L
Bicarbonate 12 mmol/L
Glucose 400 mg/dL
Creatinine 2.5 mg/dL
BUN 35 mg/dL
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Assessment
This presentation is consistent with necrotizing fasciitis. The patient is a poorly controlled
diabetic with a very serious skin and soft tissue infection that is rapidly progressing.
Cellulitis involves the skin and subcutaneous tissue. Patients with cellulitis very rarely have
high fever or leukocytosis. If a cellulitis spreads rapidly or has tense edema or discoloration or
blister formation, one must consider necrotizing fasciitis. If the PE is uncertain, CT may be
helpful by showing gas formation, though clinical judgment is still the most important element
in diagnosis.
The gold standard for diagnosis is tissue biopsy obtained during surgical exploration. Nothing
else can rule out the diagnosis.
Further Diagnostic Testing
Basic Science Correlate
Best initial management is early aggressive surgical exploration and debridement of
necrotic tissue, together with broad spectrum empiric antibiotic therapy, and hemodynamic
support
Surgery is indicated in the setting of severe pain, toxicity, fever, and elevated serum creatine
kinase, with or without radiographic evidence of fasciitis
Antibiotic therapy without debridement is associated with mortality rate approaching 100%
Aggressive supportive care with IV fluids and vasopressors may be needed for
hemodynamic instability
CT (or plain x-ray) shows gas formation in different areas of the right leg, as well as
swelling and necrosis of various muscle groups
45
Necrotizing fasciitis is a destruction of the fascia and muscle through the release of
toxins (virulence factors), which include streptococcal pyogenic exotoxins. Most cases
are polymicrobial including anaerobes and aerobes. Common organisms include group
A streptococcus (Streptococcus pyogenes), staphylococcus aureus, clostridium
perfringens, Bacteroides fragilis, and Aeromonas.
CLINICAL PEARL
Any serious skin and soft tissue infection caused by group A streptococcus—
specifically necrotizing fasciitis—is treated with immediate surgical debridement and
penicillin with clindamycin. Most cases are caused by a mixed flora and require
immediate surgical debridement along with 1 of the following:
Clindamycin inhibits production of exotoxins by binding to and inhibiting the 50S
subunit of the bacterial ribosome.
Penicillin inhibits the formation of peptidoglycan cross-links in the bacterial cell
wall. Its 4-membered β-lactam ring binds to the enzyme DD-transpeptidase. As a
consequence, DD-transpeptidase cannot catalyze formation of these cross-links, and
an imbalance between cell wall production and degradation develops, causing the
cell to rapidly die.
Vancomycin or daptomycin or tigacycline or ceftaroline or linezolid (to cover
MRSA) plus (coverage for gram negative, including pseudomonas plus anaerobes)
Imipenem/meropenem
Pipercillin/tazobactam
Ticarcillin/clavulinate plus clindamycin for toxin production
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Clostridium perfringens is a rare cause from deep stab wounds or black tar heroin
abuse (skin popping is when people inject heroin into subcutaneous tissue). Treat with
penicillin plus clindamycin.
Discussion
Necrotizing fasciitis has a high mortality. Clinical judgment is still the most important element
in diagnosis. Signs include:
Pain may be out-of-proportion to findings.
CT or MRI finding may be helpful but may be non-specific. Leukocytosis, thrombocytopenia,
and elevated creatinine with lactic acidosis may also be seen. CT may show fascia edema and
subcutaneous gas.
If the suspicion is there, immediate surgical exploration is the correct answer. The gold
standard for diagnosis is tissue biopsy obtained during surgical exploration. Nothing else can
rule out the diagnosis. Time to first debridement and its adequacy are predictors of survival.
Final Diagnosis
Necrotizing fasciitis
Tense edema
Grayish, purplish or other discolored wound drainage
Vesicles or bullae
Necrosis
Ulcers
Crepitus
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Case 4
Chief Complaint
“I’ve had a fever, headache, and neck stiffness for 2 days.”
History and Physical Examination
A 14-year-old boy, who is in generally excellent health, is brought to the emergency
department by his parents because of high fever, headache, and neck stiffness for the last 2
days. He has become more ill over the morning. He uses no medications, has no allergies,
and is not sexually active.
Physical examination reveals a thin and muscular boy lying on the stretcher with his hands
over his eyes. His T is 38° C (104° F). Examination of the head, eyes, ears, nose, and
throat is normal, and fundoscopic examination shows no papilledema. There is moderate
nuchal rigidity and marked photophobia. Heart, lung, and abdominal examinations are
normal. He is oriented to time and place. He knows his own name and he can recognize
his parents. There are no focal motor or sensory deficits. Babinski reflex shows toes that
are down-going.
Differential Diagnosis
Bacterial meningitis1.
Viral meningitis2.
Viral encephalitis3.
Arboviral encephalitis4.
49
Initial Management
Setting: emergency department
Diagnostic/Therapeutic Plan
Test Results
Assessment
The acute onset and high fever with disorientation point toward an infectious etiology. The
pronounced meningeal symptoms (headache, neck stiffness, photophobia) all point toward a
meningitis rather than an encephalitis, though it can be difficult to distinguish them clinically.
The patient is awake and has a nonfocal neurologic examination.
A clinical diagnosis of encephalitis requires more than a headache. The absence of
papilledema, confusion, and focal neurologic findings point away from any evidence of CNS
mass lesion and generally indicate that it is safe to perform a lumbar puncture without CT scan
of the head first. The differential on the cell count showing neutrophils and the high total WBC
count are quite characteristic of a bacterial etiology.
CT head should be done before the LP only if the patient has altered mental status,
papilledema, seizures, focal deficits, severely immunocompromised status (HIV or transplant).
Lumbar puncture
WBC 3500/mm
3
with 95% neutrophils
Negative Gram stain
Elevated protein
Decreased glucose
CSF culture: Streptococcus pneumoniae
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