Surgical Management of Soft Tissue Methicillin Resistant Staphylococcus Aureus Abscesses
An examination of the surgical clearing of a Staphylococcus aureus soft-tissue abscess infection
By Richard E. Blair, DO, MPH, Lieutenant Colonel, USAF, Medical Corps
The most common pathogen cultured from a soft tissue abscess is the gram positive cocci, Staphylococcus aureus (S. aureus).(1) S. aureus is a common inhabitant of human skin, where it resides as part of the normal dermal flora. However, if the integrity of the dermis is compromised, S. aureus may enter the deeper subcutaneous tissues. The organism may then serve as a nadir for infection and subsequent abscess formation. Infection may be further complicated in those with a blunted immune response.
Patients suffering from diabetes, Acquired Immune Deficiency Syndrome (AIDS), and those undergoing chemotherapy may be particularly susceptible to opportunistic S. aureus infections and abscesses.(2)
In the otherwise healthy patient, an abscess may first appear as a small erythematous macule, which develops at the site of a break in the skin. The lesion matures into a papule with increasing induration, tenderness and erythema. Macrophages respond to the area and release an array of cytokines, which result in further recruitment of inflammatory factors. The lesion becomes raised, painful and tense. Additionally, it fills with purulent debris (pus) creating an osmotic gradient, resulting in an increase in both abscess size and pressure. Pain ensues. Liquifaction necrosis develops and purulent exudates form. Occasionally, lesions exhibit “pointing,” by which pus may be observed beneath the surface of the abscess.
At the above stage, the patient will present to the Emergency Department or Primary Care Provider seeking treatment for a rapidly developing and exquisitely tender “boil.”
The physician must take into account the patient’s presentation if lesion resolution is to be completely and successfully attained. A careful and thorough history and physical is required.
Several important facts must be established; is the patient diabetic or otherwise immunocompromised? Does the patient exhibit any symptoms such as chills or fever which may indicate a serious systemic infection? Is abscess development a recurring problem for the patient, or an isolated incident?
The location and appearance of the lesion must be thoroughly assessed. Large and ill-defined lesions may require hospitalization and treatment with intravenous antibiotics. Lesions to the face, peri-orbital areas, or those overlying neurovascular, joint or hand spaces must be dealt with delicately and expeditiously, often by a specialist, in order to reduce morbidity and mortality.(3) These may include neuropathy, nerve damage, etc.
Immunocompromised patients who demonstrate systemic symptoms, those who present with large lesions and infections which affect critical regions must be admitted for immediate attention. Blood and abscess cultures must be obtained. A complete blood count, as well as blood chemistries, should be ordered. Often, a Type II diabetic may be identified by elevated blood glucose levels attained during a work up for repeated abscess formation. Empiric antibiotic therapy in accordance with institution antibiograms should be initiated without haste. Surgical consultations may be in order to properly assess the severity of infection and determine if operative intervention is required. Imaging studies may be necessary to rule out bony involvement, or, the family physician may be ordered to assess the severity.(4)
Fortunately, the majority of those presenting with an abscess do not fall into the seriously ill category. Usually, the patient is afebrile with a chief complaint of a solitary red, painful and tender lesion which has developed over the course of several days. The area is well demarcated, and may have spontaneously ruptured and drained. Purulent debris often may be oozing from the abscess site. A thorough physical exam will frequently reveal similar healed lesions in the surrounding area. When queried, the patient will often describe a “boil” or “pus pocket” which developed over the course of a few days. Just as the patient was to seek medical attention, the abscess spontaneously opened, drained and healed.
Are antibiotics necessary for the otherwise healthy, a-febrile, and non-immunocompromised with a simple well-demarcated abscess? In most cases, they are not. In fact, it is the overzealous prescription of antimicrobials which has lead to the rising incidence of resistant S. aureus and the resulting increase in skin and soft tissue infections. Even so, many uncomplicated abscesses may be managed surgically, without antimicrobials. Even lesions harboring resistant bacteria may be best managed without the use of antibiotics.(5)
Proper management of an abscess is strictly surgical; simple incision, debridement, culture, drainage and packing are all that is required. A follow-up visit is needed for re-assessment and to ensure resolution.(6)
Preparing for
the Procedure
Necessary materials include one percent or two percent lidocaine with or without epinephrine. If the abscess is located on an appendage such as the ear, finger or toe, lidocaine with epinephrine must be avoided. The vasoconstrictive effects of the epinephrine may result in an ischemic affect to the region, resulting in necrosis and gangrenous amputation. Rule of thumb: if in doubt, avoid the use of lidocaine with epinephrine.
Also needed is a 5 or 10cc syringe, accompanied by a one-inch 18-gauge needle to draw up the lidocaine. A 25-gauge, 1.5-inch needle is needed for tissue infiltration. Betadine or Hibiclens® are necessary for skin preparation. A #11 or #15 scalpel blade, culturette, 4x4” gauze sterile gauze pads, sterile drape, tape and one-half inch iodiform or sterile gauze packing are needed as well. Several sets of appropriately-sized sterile gloves are best set aside and made ready in the event of glove contamination.
Performing the Procedure
Like many procedures, more time must be invested in careful preparation of materials than in the actual performance of the procedure. Additionally, the appropriate risks and benefits of the procedure must be explained to the patient. Consent must be obtained and documented in a thorough manner.
Before beginning the procedure, the patient is to be positioned comfortably in a fashion which minimizes physician fatigue and optimizes lesion exposure. The best time to do so is well before the procedure is to begin. Careful positioning is key for both physician and patient comfort.
The abscess site is thoroughly exposed in a well-lit environment. The area in question is copiously, but gently cleansed with betadine or Hibiclens®, depending on patient sensitivities and preference. It is important to keep in mind that the abscess may be profoundly tender. A simple touch to the lesion may produce an astonishing level of patient discomfort. With great care, the site is prepped as thoroughly as possible, given patient tolerance. Skin preparation coverage should be equal to or greater than the fenestration of the drape to be used for the procedure.
After skin preparation, the physician dons sterile gloves and places the sterile drape over the exposed and prepped site. Five to 10cc of lidocaine is drawn up for anesthetic infiltration. Purulent filled lesions may often be quite difficult to completely anesthetize. Anesthesia is best carried out extending several centimeters from the each end of the anticipated incision. Infiltration should be introduced along the imaginary incision line and extended outwards in a fan-like fashion 30 to 45 degrees on both sides of the lesion. Several minutes after infiltration, the area may be tested for total anesthesia using the scalpel tip. Several anesthesia attempts may often be made before complete anesthesia is achieved.
When the area is completely numbed, the operator may proceed with incision. Using a #11 blade scalpel, an incision is made beginning at the base of one apex of the lesion and proceeding in a curvilinear fashion across the apex, ending at the opposing base. Extreme caution must be exercised when the incision is performed. The contents within the abscess may be under intense pressure. Consequently, when the incision is performed, purulent liquid and debris may be expelled in a most spectacular fashion, alarming the physician, patient and any personnel whom may be assisting in the procedure. Universal precautions are of the utmost importance. Anyone present must ensure proper gloves, gown and eye shields are worn.
Following incision completion, the open cavity may then be gently massaged by the physician. Doing so will express additional amounts of pus, debris and necrotic material. The resultant material may be cultured for aerobic and anaerobic organisms. Next, hemistats or Metzenbaum scissors are inserted into the cavity and cautiously worked about in a blunt fashion. Doing so will break up adhesions and loculations, and may reveal sinus tract formations.
The resulting cavity is then thoroughly irrigated with copious amounts of sterile saline solution. Many rounds of irrigation may be required to thoroughly flush the abscess free of purulent matter. A sterile gloved finger may be inserted into the cavity to gingerly explore and identify more stubborn loculations. Once again, the cavity should be thoroughly flushed.
Following incision, drainage, exploration, and irrigation, the abscess cavity must then be packed. Failure to do so will result in the defect simply “closing back up” with the re-accumulation of purulent material and debris. One-quarter inch iodiform gauze may be utilized for packing most lesions. One-half inch gauze may be reserved for larger, more spacious lesions which have produced a significant defect.
Using sterile technique, the physician may pack the wound in the following fashion: an assistant holds the container of gauze and removes the cap. The physician grasps the end of the gauze strip from the container using a set of sterile forceps or hemostats. The gauze strip end is then inserted into the abscess cavity, and fed into the defect using forceps and hemostats. Keep in mind that a significant amount of gauze may be necessary to completely fill the defect. Thus, it may be best to have two containers of gauze at the ready.
The gauze is fed into the cavity until empty spaces are occupied. For small lesions, the wooden end of a sterile cotton swab may be utilized for feeding the gauze into the lesion.
When the abscess is thoroughly packed, a one- to two-inch strip of gauze should protrude from the lesion. The gauze may then be cut, leaving a “tail” which projects from the packed cavity. The “tail” facilitates drainage, and allows the physician seen on follow-up to locate a starting point to grasp during removal of the gauze.
After the Procedure
The area is then cleansed of any blood and discharge. A loosely fitting dressing of 4x4” gauze pads may then be used to cover the lesion. It is often best to send the patient home with several packages of gauze and tape. The patient must be instructed to dress the wound loosely, thereby allowing for proper drainage, which may be quite significant. The patient must be warned not place the dressing in an occlusive fashion. Oozing is to be encouraged and expected. It may be best to explain to the patient that “the air must be able to get to the abscess” in order for proper wound drainage and resolution. If possible, the patient may be instructed to sleep with the abscess uncovered of any dressing. Doing so facilitates proper aeration and encourages further drainage.
At this point, the patient often feels significantly better, experiencing a decrease in pain and discomfort. With the intra-abscess pressure relieved, the patient may not need analgesics. Nevertheless, it is best to prescribe a mild to moderate opioid analgesic in the event the lesion begins to “throb” after the initial anesthetic effect diminishes.
Proper follow-up and wound care instructions are essential. The patient must be given a “wound care sheet,” which details proper care and management of the wound. Continuous drainage may be expected for the next 12 to 24 hours, after which the wound will begin to dry and heal. Pain, erythema, edema and discharge may continue, but should slowly taper off. Wound care instructions should include signs and symptoms which may indicate complications, including fever, worsening pain and lymphangitis. The patient is to be instructed that the presence of any of the above symptoms calls for emergent investigation and assessment.
Barring any complications, the patient is to follow-up within 24 to 48 hours for a wound check and re-packing. Follow up may be accomplished via a primary care physician, surgeon or local emergency department. During follow-up, the wound may be inspected and re-packed, culture results identified, and the patient’s comfort assessed. The majority of patients will subjectively feel much better at follow-up.
Accordingly, further follow-up visits will be scheduled for wound re-assessment, repacking and resolution. At each visit, it is vital to ensure the patient understands the importance of scrupulous wound care and continued follow-up.
After several visits, the packing may be removed completely after wound healing is established, and discharge has ceased. There is no established guideline as to when packing is no longer needed. The wound is to be re-assessed at each visit, and findings will dictate further actions.
Conclusion
Left to its own devices, the otherwise healthy human body will often heal itself, per the basic tenents of osteopathic medicine, especially when under the care of an astute primary care physician. Time, common sense and evidence-based guidelines are the prudent course of action in most healthy patients.
However, the challenge lies in the ability to discern when the body may, indeed, be in need of antimicrobials to clear a bacterial infection. Patients at the extremes of age, immunocompromised, diabetic or who are systemically ill require deliberation and skillful care. If in doubt, specialists should be consulted for guidance and re-assurance. If a course of action gives one the sense of discomfort, consultation is the prudent course of action.
The indiscriminate use of broad spectrum antibiotics during the last few decades has led to bacterial genetic mutations resulting in “superbugs;” profoundly stubborn and resistant to standard antimicrobials.(7) Osteopathic physicians must take the initiative in appropriate administration of antibiotics. If not, we may all awaken someday to find antibiotics a “controlled substance” prescribed only by specialists.
Dr. Blair is currently on active duty as a Flight Surgeon with the United States Air Force’s 51st Aerospace Medicine Squadron at Osan Air Base, Republic of Korea.
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