Soft Tissue Infection Flashcards
A 45-year-old gardener with a 10-year history of poorly controlled type 2 diabetes mellitus comes to the emergency department because of excruciating pain and swelling of the left forearm 1 day after he scraped his left arm on a rosebush. Physical examination shows extreme tenderness, edema, and crepitus. Which of the following is the most appropriate management? A) CT scan B) Econazole C) Hyperbaric oxygen D) Immediate surgical debridement
D) Immediate surgical debridement
Necrotizing fasciitis infects _____ and spares _____
Necrotizing fasciitis is a severe soft-tissue infection affecting the skin, subcutaneous tissue, and fascia. It characteristically spares the underlying muscle.
Necrotizing fasciitis inciting event
The inciting event for necrotizing fasciitis is often trauma, even minor trauma and small puncture wounds, but hematogenous spread is also a recognized etiology
Most common diseases associated with necrotizing fasciitis
The vast majority of patients have some form of chronic debilitating disease that weakens the immune system. Diabetes mellitus appears to be the most common disease, but these may include substance abuse and renal failure. These patients are at higher risk for increased mortality
Type I necrotizing fasciitis
Two types of necrotizing fasciitis have been described. Type I are mixed aerobic and anaerobic infections, with facultative anaerobic bacteria and non-group A streptococci being present. This is the most common type and is present in about 75% of cases.
Type II necrotizing fasciitis
Type II infections are monomicrobic and are caused by group A Streptococcus species alone or in combination with staphylococcal species. For this reason, antibiotic coverage should be broad
Progression / stages of necrotizing fasciitis
The disease progresses quickly but does evolve through several stages. Initial symptoms include tenderness, erythema, edema, warm skin, and fever; however, symptoms may vary depending on patient characteristics. Initial lab findings may include leukocytosis, thrombocytopenia, and hyperkalemia, but these are variable. When critical skin ischemia occurs, blisters or bullae are formed. In the late stage, lesions turn black and necrotic and are anesthetic as the nerves become involved.
Mortality rate for necrotizing fasciitis, and patient population with increased mortality
Mortality rates for necrotizing fasciitis are reported to be 10 to 75% and are increased in patients with underlying immune compromise, delayed treatment, or involvement of the chest wall.
Hyperbaric oxygen and necrotizing fasciitis
Most authorities agree that hyperbaric oxygen is to be recommended for the treatment of necrotizing fasciitis as an adjunct, if facilities are available and there is no delay in surgical debridement. However, most studies regarding the efficacy of hyperbaric oxygen are anecdotal with a distinct lack of properly designed prospective randomized controlled trials.
A 24-year-old man comes to the emergency department 6 hours after sustaining an open distal radius fracture and loss of soft tissue while he was working on a farm. History includes diabetes mellitus. On physical examination, distal pulses and sensation are intact. Debridement and repair with open reduction and internal fixation are planned. Which of the following factors places this patient at greatest risk for infection postoperatively?
A) Gustilo fracture classification
B) History of diabetes mellitus
C) Method of fracture fixation
D) Period of time from injury to initial debridement
E) Type of contamination
E) Type of contamination
Correlation of Gustilo-Anderson fracture classification and infection - upper extremity
The Gustilo–Anderson fracture classification has been found to have some correlation with open fracture infection rates, but this relationship is not as strong in the distal radius as it is in long bones of the lower extremity.
Systematic illness and correlation with infection in distal radius fractures
A history of systemic illness, such as diabetes mellitus, and the type of fracture fixation seem to have a modest correlation to postoperative infections in distal radius fractures, but the findings are generally not statistically significant.
Schedule of debridement vs infection rate
The timing of the initial debridement, as long as it occurs within the first 24 hours of injury, does not significantly affect infection rate. In contrast, there is evidence to suggest that performing multiple serial debridements in significantly contaminated wounds is of benefit in preventing postoperative infection.
A 45-year-old woman comes to the emergency department because of redness at the site of injury 24 hours after being bitten by a cat. Temperature is 98.6 °F (37.0 °C), heart rate is 77 bpm, respirations are 16/min, and blood pressure is 125/82 mmHg. Physical examination shows mild erythema and edema around the puncture marks over the volar second phalanx of the long finger of the left hand. No purulent material is expressed. Resting position of the digit is normal, and there is no pain with passive extension. Assuming that the patient has no allergies to medications, which of the following is the most appropriate antimicrobial therapy? A ) Amoxicillin-clavulanate B ) Cefazolin C ) Cephalexin D ) Erythromycin E ) Vancomycin and gentamicin
A ) Amoxicillin-clavulanate
Common organisms involved in cat bite infections
Cat bites usually result in puncture wounds because of their long, slender, sharp teeth. It has been reported that as many as 80%of cat bites become infected. Pasteurella species are the most common, occurring in as many as 75% of cat bite infections. Other types of bacteria can also be involved as well, including Streptococci, Staphylococci, and anaerobes.
Pasteurella species are susceptible to _____ and resistant to ______
Pasteurella species are susceptible to penicillin, ampicillin, second-and third-generation cephalosporins, doxycycline, trimethoprim-sulfamethoxazole, fluoroquinolones, clarithromycin, and azithromycin, but are resistant to cephalexin, dicloxacillin, erythromycin, and clindamycin.
Appropriate choices for prophylaxis and treatment of cat bite wounds
Appropriate choices for prophylaxis and treatment of cat bite wounds would include amoxicillin and clavulanate or a combination of penicillin plus cephalexin. For those patients who have an allergy to penicillin, moxifloxacin or combination therapy with ciprofloxacin and clindamycin are appropriate choices. Azithromycin may also be effective for the penicillin-allergic patient, but it has less activity against anaerobes.
Coverage for community-acquired MRSA (CA-MRSA) infection is not recommended because oral colonization of the human and animal mouth with CA-MRSA is unlikely.
A 40-year-old woman is undergoing chemotherapy for metastatic lung cancer. During administration of her first dose of doxorubicin, she reports pain at the site of injection. The following day, physical examination shows the hand to be swollen and an ulcer measuring 2x3 cm is seen over the dorsum surrounded by an area of ischemia. Which of the following is the most appropriate immediate treatment?
A ) Administration of hyperbaric oxygen
B ) Applicationof cold packs
C ) Application of hot packs
D ) Application of topical dimethyl sulfoxide
E ) Immediate surgical excision and autografting
D ) Application of topical dimethyl sulfoxide
In the case of doxorubicin extravasation injury, cold compresses may exacerbate the complication by venous constriction, which localizes the drug, whereas hot packs may cause vasodilatation with further extravasation.
The specific treatment of extravasation injury is dependent on:
The specific treatment of an extravasation injury is dependent on the drug infused.
Treatment of extravasation of anthracyclines
Application of topical dimethyl sulfoxide has been advocated for the treatment of extravasation of anthracyclines and is supported by several studies.
Extravasation of surgical excision
Early excision for extravasation injury is rarely performed without evidence of at least ulceration, and the main indication would then be for pain control. In the scenario described, an option would be early surgical debridement and delayed closure of the wound; however, some of the surrounding skin may heal. Thus, a conservative initial approach with later excision after 2 to 3 weeks is recommended since this will give a better cosmetic result.
A 43-year-old man who is HIV positive comes to the emergency department because of a 1-month history of gradually progressive swelling and pain in the tip of the right index finger. Examination shows significant swelling, erythema, and small vesicles on the fingertip and perionychium. A few nodular, reddish brown lesions are noted on the chest and forearms. Which of the following is the most appropriate management? A ) Administration of acyclovir B ) Administration of cefuroxime C ) Administration of ketoconazole cream D ) Excision of proximal nail plate E ) Incision and drainage
A ) Administration of acyclovir
Diagnosis of HSV infection of the hand
Herpes simplex virus (HSV) infection of the hand is clinically diagnosed when characteristic multiple vesicular lesions on an erythematous base are present.
The staining of scrapings from the base of the lesions with a Tzanck preparation for a Papanicolaou stain demonstrates giant cells or intranuclear inclusions of HSV infection.
Duration of HSV infection of the hand
HSV hand infection generally resolves within 3 weeks.
In case of prolonged HSV infection of the hand
HSV hand infection generally resolves within 3 weeks. If symptoms last longer than 3 weeks, suggestion of immunosuppression or AIDS should be raised.
Treatment of HSV infection of the hand
Treatment with an antiviral such as acyclovir is recommended for HSV infection of the hand
Cause of acute paronychia
Acute paronychia is most commonly caused by bacterial inoculation, and the most common agent is Staphylococcus aureus
Cause of chronic paronychia
Chronic bacterial infections of the subungual space are usually secondary infections of a preexisting fungal infection.
The fungal organismsare the primary cause of chronic paronychia. Candida is the most common infecting organism. Most often affecting women, this low-grade smoldering infection causes thickening and fibrosis.
Treatment of chronic paronychia
Topical and systemic antifungal agents have been used for treatmentof minimal-to-moderate fungal infections. For extensive infection, the nail plate is removed and topical antifungals are used.
A 60-year-old woman with type 1 diabetes mellitus has a 1-cm puncture wound to the lower leg sustained 2 days ago. Physical examination shows erythema of the surrounding tissue, tenderness of the entire calf, and crepitus. Which of the following is the most appropriate initial management of the wound? A ) Hyperbaric oxygen therapy B ) Silver sulfadiazine dressing C ) Surgical debridement D ) Unna boot compression dressing E ) Vacuum-assisted closure therapy
C ) Surgical debridement
Necrotizing fasciitis must be suspected in any patient with a compromised immune system, even when he or she has a relatively small surfacewound.
A 25-year-old man who is a soldier from Afghanistan is evaluated because of deep frostbite of the right hand after being in the field for 36 hours. Rewarming is performed in the field. He is transferred to a hospital for further evaluation. Physical examination shows hemorrhagic blisters and eschar formation on the hand, erythema of the surrounding area, and streaking up the forearm. Which of the following is the most appropriate next step in management?
A ) Administration of dextran
B ) Administration of penicillin
C ) Hyperbaric oxygen therapy
D ) Intra-arterial injection of reserpine
E ) Observation
B ) Administration of penicillin
Field management of frostbite
Field management for frostbite includes rapid rewarming of the affected area with circulating water at 104 to 107.6 °F (40 to 42 °C) for a period of 15 to 30 minutes, protection from mechanical trauma, and appropriate analgesia.
Following initial field management of frostbite
Next steps in management of frostbite following initial field management include elevation, antitetanus prophylaxis, debridement of clear blisters, leaving hemorrhagic blisters intact, and application of aloe vera. Penicillin should be administered for cellulitis.
Adjuvant therapies for frostbite for which there is equivocal/scant data
Adjuvant therapies can include anticoagulation, thrombolytics, hyperbaric oxygen, and sympathetic blockade; however, data to support these therapies are scant and equivocal at best.
Timing for definitive surgical amputation after frostbite
Definitive surgical amputation following frostbite should be delayed for at least 3 weeks to allow for tissues to demarcate, in terms of viability
A 55-year-old man comes to the emergency department because of acute onset of pain, swelling, and erythema of the right groin, lower abdominal wall, and right scrotum. He has type 1 diabetes mellitus which is controlled with insulin. He has smoked one pack of cigarettes daily for the past 30 years. He weighs 145 kg (320 lb); BMI is 35 kg/m2. Temperature is 38.3°C (101°F), pulse is 136 bpm, and blood pressure is 90/40 mmHg. In addition to admission to the hospital and administration of pain medication, which of the following is the most appropriate sequence in management?
A ) Intravenous antibiotics, hyperbaric oxygen, intravenous hydration
B ) Intravenous hydration, immediate surgical debridement, right orchiectomy
C ) Intravenous hydration, intravenous broad-spectrum antibiotics, CT of abdomen
D ) Intravenous hydration, intravenous broad-spectrum antibiotics, immediate surgical debridement
E ) Observation, intravenous antibiotics
D ) Intravenous hydration, intravenous broad-spectrum antibiotics, immediate surgical debridement
Orchiectomy is rarely needed, as testicles have their own blood supply and are protected by external spermatic fascia.
Predisposing factors for Fournier disease
Diabetes mellitus, alcoholism, heavy smoking, leukemia, and AIDS can predispose to Fournier disease.
Common sources of infection for Fournier disease
Common sources of Fournier disease include urogenital disease, trauma, or recent manipulation (iatrogenic trauma, ie, endoscopic procedures)
Antibiotics for Fournier disease should include
Key steps in treatment of Fournier disease include early diagnosis, intravenous hydration, and broad-spectrum antibiotics (anaerobic coverage for Clostridium perfringensshould continue as it is difficult to culture this).
Mortality rate from Fournier gangrene
Mortality rate for Fournier gangrene is quoted to be 7% to 75%, with the higher rate in patients with diabetes, alcoholism, and in cases of delayed diagnosis
A 56-year-old woman develops a necrotizing infection of the abdominal wall (shown). Appropriate antibiotics are started and devitalized tissue is debrided. Which of the following interventions is most likely to decrease mortality? A ) High-dose corticosteroids B ) Hyperbaric oxygen treatment C ) Intravenous gamma globulin D ) Topical papain-urea ointment E ) Vacuum-assisted closure device
B ) Hyperbaric oxygen treatment
Some studies have shown that mortality rate of necrotizing infections can be reduced with:
Necrotizing soft-tissue infections are rapidly progressive, polymicrobial infections that require prompt diagnosis, debridement of devitalized tissue, and administration of appropriate antibiotics. Some studies have shown that mortality rates in necrotizing infections can be reduced with the addition of hyperbaric oxygen treatment.
A 23-year-old man is brought to the emergency department one hour after sustaining a snake bite to the lower right leg while hiking. The description of the snake is consistent with that of a copperhead. The patient does not recall his immunization status. Vital signs are stable. Physical examination shows mild edema around the bite. No neurologic deficits are noted. Coagulation and routine laboratory studies are ordered. Intravenous fluids are started. Which of the following is the most appropriate next step in management?
A ) Administration of equine antivenin
B ) Administration of tetanus toxoid
C ) Debridement of the wound and initiation of suction therapy
D ) Elevation and application of a tourniquet
E ) Prophylactic fasciotomy
B ) Administration of tetanus toxoid
Percent of snake bites that are dry bites
10% to 50% of snake bites have been reported as dry bites
First aid after a snake bite
Acute first aid interventions after snake bite include avoiding excessive activity of the affected site, immobilization in a neutral position, and expeditious transportation to a hospital.
Potential complications of antivenin
Anaphylaxis and serum sickness are potential significant complications of equine antivenin.
Indication for antivenin administration
The general indication for antivenin administration is progressive venom injury. This is defined as worsening local injury (eg,swelling, pain, or ecchymosis), the onset of clinical coagulopathy, or the development of systemic effects including hypotension or changes in mental status. The patient should be monitored closely because the clinical presentation can change rapidly. Antivenin therapy should be institutedif signs or symptoms of envenomation develop or progress.
Snake with the most potent venom
Rattlesnake bites deliver the most potent venom and are responsible for the majority of fatalities from snake bites;
Debridement of snake bite site
Debridement of the bite site and suction therapy have not been shown to be beneficial in reducing the effects of envenomation and can cause additional necrosis to the tissue under the suction cup.
Suction therapy of a snake bite site
Debridement of the bite site and suction therapy have not been shown to be beneficial in reducing the effects of envenomation and can cause additional necrosis to the tissue under the suction cup.
Arterial tourniquet of a snake bite site
Arterial tourniquets are contraindicated because they may worsen tissue ischemia and necrosis
Concern for compartment syndrome after snake bite
Fasciotomy should be performed only for clinical signs and symptoms of compartment syndrome. Compartment syndrome and infection from extremity bites are extremely rare.
But watch for it!
A 57-year-old man with type 2 diabetes mellitus comes to the emergency department because of redness and swelling of the dorsum of his right hand five hours after being bitten by an insect. Intravenous first-generation cephalosporin is started. Three hours later, the area of redness has extended to his shoulder and chest; temperature is 103.8°F (39.9°C), pulse is 110 bpm, and blood pressure is 100/55 mmHg. Which of the following is the most appropriate management?
A ) Blood cultures and empiric addition of anti fungal antibiotics
B ) Elevation and ice compression to his extremity
C ) Fasciotomy of compartments
D ) Increase in dosage of intravenous antibiotics
E ) Operative incision, drainage, and debridement of affected tissues
E ) Operative incision, drainage, and debridement of affected tissues
A 15-year-old girl is brought to the emergency department 24 hours after being bitten on the left index finger pulp pad while playing with her friend’s cat. The patient received a tetanus immunization three years ago. Temperature is 37°C (98.6°F). Physical examination shows mild erythema surrounding a fluctuant area beneath a sealed puncture wound. No motor or sensory deficits are noted. Radiographs show no abnormalities. Leukocyte count is 12,800/mm3. In addition to adequate drainage of the wound, which of the following is the most appropriate next step in management?
A ) Administration of amoxicillin and clavulanate
B ) Administration of ciprofloxacin
C ) Administration of rabies toxoid
D ) Administration of tetanus immune globulin
E ) Observation
A ) Administration of amoxicillin and clavulanate
Microbiology/treatment of cat and dog bites
Cat and dog bite infections have a complex microbiologic mix, with Pasteurellaas the most frequent isolate. Common aerobes isolated include streptococci, staphylococci, Moraxella, and Neisseria; common anaerobes include Fusobacterium, Bacteroides, Porphyromonas, and Prevotella.
Antibiotic treatment for cat/dog bites
Patients are most often treated with a combination of a β-lactam antibiotic and a β-lactamase inhibitor, such as amoxicillin and clavulanic acid.
Alternative treatments include clindamycin plus fluoroquinolone for adults and clindamycin and trimethoprim/sulfamethoxazole for children.
Surgical management of cat vs dog bites
In general, cat bites tend to be small puncture wounds that seal almost immediately; thus, wounds should be opened sufficiently to be cleaned and allowed to drain. Dog bite wounds tend to be longitudinal lacerations that are more likely to stay open by themselves. However, canine lacerations, as compared to cat bite punctures, are more likely to result in direct structural damage to nerves, tendons, vessels, and joint structures.
Indication for administration of tetanus immune globulin
Administration of tetanus immune globulin is recommended only for patients with tetanus-prone wounds who have never completed a primary immunization series.
Tetanus prophylaxus for patient with acute soft tissue injury and no previous immunization
If a patient with an acute soft-tissue injury has not been immunized previously, a tetanus toxoid booster is required. The patient must complete the series.
Booster doses for tetanus for previously immunized patient after acute soft tissue injury
If the patient has been immunized previously, a booster dose is given if the last dose was more than five years previously (for a tetanus-prone wound) or more than 10 years previously (for a nontetanus-prone wound).
Management of patients with acute soft tissue injury and contraindication to tetanus toxoid
Patients with a contraindication to tetanus toxoid must be managed with tetanus immune globulin alone.
A 53-year-old man returns to the emergency department because he has redness, swelling, and severe pain in the left upper extremity two days after he sustained a laceration to the left hand. Current temperature is 102°F (38.9°C) and heart rate is 126/min. Current examination shows crepitus extending into the left forearm. Radiograph shows some gas in the softtissue. Which of the following is the most likely causative organism? A ) Eikenella corrodens B ) Pasteurella multocida C ) Pseudomonas aeruginosa D ) Staphylococcus epidermidis E ) Streptococcus pyogenes
E ) Streptococcus pyogenes
Progressive clinical presentation of necrotizing fasciitis
Symptoms usually begin with localized erythema and swelling and may mimic cellulitisin the early stages. Severe pain, crepitus, and systemic toxicity can provide clues to the diagnosis. Radiographs may show air in the soft tissues, and patients may exhibit grayish, watery discharge (dishwater pus).
Eikenella corrodens
Eikenella corrodensis an anaerobic organism present in human oral flora and has been associated with human bite wounds.
Pasteurella multocida
Pasteurella multocidais a gram-negative anaerobic bacterium most commonly associated with cat bite infections.
Staphylococcus epidermidis
Staphylococcus epidermidisis a gram-positive coccus present on the skin. It has been associated with implant infections.
A 2-year-old boy is brought to the emergency department because he has had lethargy, fever, and a rash over the extremities for the past 10 hours. Temperature is 39.9EC (103.8EF). Physical examination shows petechiae over the trunk and arms. Over thenext three hours, the rash coalesces to hemorrhagic bullae, and the diagnosis of purpura fulminans is confirmed. Each of the following management interventions is appropriate EXCEPT
(A)administration of activated protein C
(B)broad-spectrum antibiotic therapy
(C)early wound debridement and amputation of ischemic digits
(D)fasciotomy of extremities
(E)fluid resuscitation with inotropic support
(C)early wound debridement and amputation of ischemic digits
Purpura fulminans
Purpura fulminans is a frequently fatal, rapidly evolving syndrome of septic shock and hemorrhagic bullae, which can result in massive desquamation.
Management of purpura fulminans
Management includes prompt recognition of the infection (which is usually caused by Neisseria meningitidis), initiation of broad-spectrum antibiotic therapy, mechanical ventilation, and aggressive fluid resuscitation with inotropic support. Disseminated intravascular coagulopathy (DIC) develops, and patients seem to benefit from replacement of activated protein C.
Purpura fulminans is most often caused by
usually caused by Neisseria meningitidis
Improving limb salvage in purpura fulminans
need for early fasciotomy to improve limb salvage. It is difficult to determine tissue viability during the resuscitation period; therefore, debridement, coverage, and amputation are delayed until demarcation has occurred
A 27-year-old woman with a history ofintravenous drug use has a persistent abscess and cellulitis of the dorsal aspect of the left hand. A photograph of the hand is shown. Three days ago, incision and drainage were performed using local anesthesia in the emergency department, and the patientwas then admitted to the hospital for intravenous administration of piperacillin with tazobactam. Results of culture of thwound tissue are pending. Current physical examination shows that the cellulitis has not resolved satisfactorily. Which of the following is the most likely causative organism of this infection? (A)Bacteroides fragilis (B)Escherichia coli (C)Group B streptococcus (D)Pseudomonas aeruginosa (E)Staphylococcus aureus
(E)Staphylococcus aureus
The infection described is most likely caused by a subset of Staphylococcus aureus, which is methicillin-resistant
