1.) Do you routinely pack abscesses after I & D? If so, what is your endpoint (i.e., when do you stop re-packing, and when do you stop ED follow-up)?

Incision and drainage remains the cornerstone of therapy for simple cutaneous abscesses. The procedure entails administering analgesia/anesthesia, incising the abscess, probing to break up loculations, and (for some) irrigating the abscess pocket. Many physicians place gauze strips inside the abscess pocket to keep the cavity open, the thought being that the wick facilitates further drainage and prevents premature wound closure. Little high quality evidence exists in support of routine packing of abscesses after I & D, and packing may actually be harmful due to increased patient discomfort and increased need for follow-up visits.

One of the first pilot studies in the EM literature to evaluate packing of abscesses was a prospective, randomized, single blinded study which randomized 48 patients with simple cutaneous abscesses < 5 cm into packing versus no packing, and assessed pain scores and need for further intervention at 48 hour follow-up (O’Malley, 2009). Patients in the packing group reported higher pain scores and used more pain medication compared to the non-packing group, with no decrease in morbidity or requirement for further intervention. Though the study was small and only followed patients for 48 hours post-procedure, the data suggests that packing after I & D may be unnecessary for simple cutaneous abscesses < 5 cm. Further large-scale randomized studies are needed, and no recommendations can be inferred from this data for abscesses > 5cm.

Similar conclusions are seen in the pediatric literature. A randomized, single blinded, prospective study compared packing after I & D to no packing in 57 immunocompetent pediatric patients with abscesses > 1 cm (Kessler, 2012). Patients were randomized into two groups, and had follow-up at 48 hours to assess treatment failure, need for re-intervention, and pain scores. Phone interviews were conducted at 1 week and 1 month to assess abscess healing and recurrence. The study found similar rates of treatment failure/intervention, pain, and healing between the two groups.

Despite the lack of evidence regarding packing and follow-up, a recent study demonstrates that the majority of physicians still routinely pack abscesses (Schmitz, 2013). The authors analyzed results from 350 surveys of attending physicians, residents, and mid-level providers across 15 US emergency departments, and found that only 48% of providers routinely irrigated after I & D, and 91% packed abscess cavities after I & D. Follow-up visits were most often recommended at 48 hours unless the provider deemed the wound concerning enough for sooner follow-up.

Data pertaining to the follow-up care after an abscess is packed is lacking. Though no evidence exists to support the recommendation, general guidelines for abscess management suggest having the patient return within 48 hours for initial follow up, at which time the packing is either removed or changed. No evidence-based data exists to guide the duration or frequency of follow-up visits and packing changes, although it is important to advise patients to return for worsening symptoms.

2.) Do you ever use primary closure after abscess I & D? What about loop drainage?

Dating back to the 1950’s, several variations of procedural abscess management have been proposed, including primary closure after incision and drainage, and loop drainage. As opposed to secondary closure (whereby the tissue edges are left open to heal via secondary intention), primary closure entails placing sutures immediately after abscess intervention to approximate the opposing edges of the abscess pocket. This can be done using simple interrupted sutures, or more commonly by placing deeper mattress sutures in an attempt to obliterate the remaining cavity space. Primary closure is an attractive option based on the potential to speed healing, reduce pain, and improve scarring when compared to secondary closure.

Though the majority of the literature pertaining to primary versus secondary closure of abscesses comes from the surgical literature, there are some studies that have been done in ED patient populations. Adam Singer has published two studies, the first being a systematic review/meta-analysis pertaining to mostly surgical patients, followed by a randomized controlled trial which studied an ED patient population. The systematic review (Singer, 2011) searched articles from Medline, PubMed, EMBASE, CINAHL, and the Cochrane database between 1950-2009, and retrieved 7 randomized controlled trials, which collectively assessed 915 patients randomized to primary versus secondary closure. The objective of the study was to compare time to healing and recurrence rates between the two groups. The review found that primary closure resulted in faster healing (7.8 days versus 15 days) and shorter time to return to work (4.1 days versus 14.6 days) compared to secondary closure, with similar rates of abscess recurrence and complications. The review was limited by the fact that most of the included trials were older, and were conducted before the outbreak of community-acquired MRSA in the 1990’s, so results may not be applicable to today’s patient population. Also, the majority of patients received I & D under general anesthesia in the OR, and about half of cases were abscesses in the anogenital region, which is not generalizable to the ED setting. It is plausible to hypothesize that breaking up loculations while the patient is under general anesthesia is much more effective than breaking up loculations during bedside I & D under local anesthesia, which may have contributed to the low rates of recurrence and complications in the primary closure group.

Two years later, Singer published a randomized controlled trial which was more specific to the emergency department patient population (Singer, 2013). The study included 56 immunocompetent patients in two diverse academic emergency departments, and randomized patients to primary versus secondary closure after I & D of abscesses < 5 cm. Patients were assessed at 48 hours and again at 7 days for degree of wound healing, complications/treatment failure, and patient satisfaction. Results showed similar healing at seven days, similar failure rates, and similar patient satisfaction scores between the two groups. The study demonstrated non-inferiority of primary closure compared to secondary closure. Without convincing evidence to suggest superiority of primary closure of abscesses in the ED at this time, more studies should be done before generalizing this technique to the ED patient population. However, there may be a role for primary closure, especially for abscesses in areas where cosmesis is of particular concern.

Another alternative to traditional I & D is loop drainage. The loop drainage procedure (Roberts, 2013) involves making a small stab incision (approx. 5 mm) at the “head” of the abscess (either the center or any area that is spontaneously draining), inserting a hemostat to break up loculations and explore the abscess cavity, manually expressing purulent drainage, irrigating, and then using the hemostat tip to “tent” the skin from beneath at the opposite end of the abscess pocket, in order to guide placement of an additional stab incision at this point. A penrose drain or silicone vessel loop is then placed into the tip of the hemostat, pulled through both incisions, and the ends tied loosely above the skin surface. Though official recommendations are lacking, most sources recommend keeping the drain in place for 7-10 days. The appealing aspects of loop drainage include no packing changes, only one follow-up visit to remove the loop, and the potential for improved healing, better cosmetic outcome, and decreased pain compared to standard I & D with packing.

Two studies (Ladd, 2010; Tsoraides, 2010) looked at loop drainage for cutaneous abscesses in children, performed in the operating room. The Ladd study was a retrospective review focusing on larger, complex abscesses (76% were MRSA), and found that average duration of loop drain was 8 days, with need for only one follow-up visit, and no recurrences, complications, or increased morbidity. The Tsoraides study also looked retrospectively at pediatric patients undergoing OR placement of loop drains for cutaneous abscesses, and results were similar except for the fact that 5.5% of the 110 patients required re-operation. These studies were both limited by their retrospective nature, lack of control group for comparison, limitation to the pediatric population, and to the operating room setting. There are anecdotal reports of loop drainage being used successfully in emergency departments for both adult and pediatric patients, but data in this setting is lacking and further studies are needed to determine the efficacy and safety of loop drainage as an alternative to standard I & D.

3.) Which patients do you consider treating with antibiotics after I & D?

With the increasing incidence of community acquired MRSA (CA-MRSA), there has been a great deal of debate pertaining to optimal treatment strategies for simple cutaneous abscesses in ED patient populations, especially regarding the need for antibiotics after abscess I & D. Recent data suggests that for simple cutaneous abscesses, routine use of antibiotics is unnecessary. This position is further backed by recommendations of the Infectious Diseases Society of America and the Centers for Disease Control, which state that with the exception of severe, recurrent or persistent abscesses, I & D alone is sufficient for uncomplicated abscesses in immunocompetent hosts. Given the potential adverse effects of antibiotic overuse and misuse, including but not limited to allergic reactions, antibiotic associated diarrhea, and increased resistance, identification of scenarios in which antibiotic use is appropriate is of utmost importance.

The EM literature on this issue dates back to the 1980’s, when the first randomized controlled trial on the topic was published (Llera, 1985). The patient population included 50 immunocompetent adult patients randomized into two groups after I & D (Cephradine vs. placebo), and similar treatment outcomes were seen in the two groups.

In a meta-analysis published in the Annals of Emergency Medicine, five studies and one abstract spanning a thirty year period were identified which addressed clinical outcomes of I & D with and without outpatient oral antibiotics (Hankin, 2007). The majority of studies concluded that simple cutaneous abscesses without overlying cellulitis can be managed with I & D alone, with no added benefit to giving antibiotics. Three of the included studies found no difference in abscess resolution between patients with MRSA abscesses treated with I & D followed by appropriate antibiotics (active against the cultured strain) versus inappropriate/discordant antibiotics (inactive against the cultured strain), further supporting the role of I & D alone. The meta-analysis was limited by the small sample size of the studies and the fact that none of the studies looked at abscesses with overlying cellulitis.

A more recent meta-analysis (Singer, 2013) looked at four randomized controlled trials totaling 589 ED patients (428 adults, 161 children) randomized to one of three antibiotics or to placebo. Though the end points of the included studies varied, the meta-analysis concluded that when added to I & D, systemic antibiotics did not significantly improve the percentage of patients with complete resolution of their abscesses 7-10 days after treatment, and that resolution of abscesses was high in both groups after I & D (88% versus 86%). Two of the trials followed patients for 30-90 days after I & D and found no difference in recurrence between the groups who got antibiotics versus placebo.

Luckily, our practice habits coincide with these recommendations. A recent survey study evaluated 350 providers from 15 different US emergency departments and showed that most providers (68%) do not routinely prescribe antibiotics for simple cutaneous abscesses in healthy patients (Schmitz, 2013).

If the data supports not using antibiotics routinely for simple cutaneous abscesses, in which patient populations should we be prescribing antibiotics after I & D? Unfortunately, most of the available research is primarily focused on healthy, immunocompetent adults with simple, uncomplicated abscesses. Substantial data exists to recommend when to not use antibiotics, with very little data available to advise when antibiotics should be used. Though research is lacking, in patients with diabetes or other immunocompromised states, large abscesses with overlying cellulitis, or with recurrent or persistent abscesses, it may be reasonable to prescribe an antibiotic after I & D. In their 2011 guidelines, the Infectious Disease Society of America emphasizes that I & D is sufficient for most simple cutaneous abscesses, but gives level A-III recommendation for antibiotics for abscesses associated with severe or extensive disease, rapid progression with associated cellulitis, signs/symptoms of systemic illness, associated comorbidities or immunosuppression, extremes of age, abscesses in difficult to drain areas (i.e. face, hand, genitalia), septic phlebitis, and lack of response to I & D alone (Liu, 2011).

4.) What antibiotics do you select for treatment of abscesses after I & D? When do you consider sending wound cultures?

Antibiotic choice has been a topic of much debate, especially in the era of CA-MRSA. MRSA was first discovered in 1961, but it wasn’t until the 1990’s that outbreaks in the community became prevalent. Risk factors for MRSA include recent antibiotic use, contact with healthcare worker or nursing home resident, recent hospitalization, diabetes and/or immunosuppression, incarceration, intravenous drug use, indwelling catheters, daycare, contact sports, and previous history of MRSA. Though risk factors may help guide decisions regarding antibiotic coverage, many patients with cutaneous CA-MRSA do not have any risk factors, making speciation and sensitivities difficult to predict.

While I & D alone is probably sufficient for the majority of abscesses (including those caused by MRSA), in patients who require antibiotics it is reasonable to cover for MRSA. Large randomized controlled trials of antibiotic choice are lacking. According to several review articles, commonly prescribed oral antibiotics include trimethoprim-sulfamethoxazole, clindamycin, and tetracycline. (Elston, 2007; Cohen, 2007). Trimethoprim-sulfamethoxazole has good activity against MRSA but does not cover for beta-hemolytic Streptococcus, so it is often paired with a first generation cephalosporin. Some concern has been raised regarding resistance to trimethoprim-sulfamethoxazole in patients with HIV since they are frequently on this medication for pneumocystis prophylaxis. However, one large study showed that 100% of MRSA isolates in this patient population in Oakland, California were susceptible (Mathews, 2005). In patients with sulfa allergy or other contraindications to trimethoprim-sulfamethoxazole, clindamycin is another option. Some strains of S. aureus have inducible resistance to clindamycin, due to presence of the “erm” gene. This means that the infection can initially be susceptible, but then develop resistance to clindamycin during therapy. The presence of the erm gene (and thus, the ability to predict strains with the potential for inducible resistance) can be detected by a double disk diffusion test (D-test), but is not 100% sensitive. Unlike trimethoprim-sulfamethoxazole, clindamycin is effective against beta-hemolytic Streptococcal species. In addition to the above-mentioned antibiotics, tetracyclines are another option. Like trimethoprim-sulfamethoxazole, tetracyclines are questionably active against beta-hemolytic streptococcus and require a second agent for full empiric coverage.

So, how do you choose the appropriate antibiotic for your patient? One study looked retrospectively at susceptibility of CA-MRSA amongst ED patients in University of Utah affiliated hospitals, and found that 98% of isolates were susceptible to trimethoprim-sulfamethoxazole, 86% were susceptible to tetracycline, and 81% were susceptible to clindamycin (Walraven, 2011). It is important to note that local resistance patterns vary according to geographical location, patient population, and can even vary hospital to hospital within the same region. It is vital to refer to your hospital antibiogram for treatment recommendations. A recent survey study assessed ED provider practices in the management of cutaneous abscesses, and found that 68% do not routinely prescribe antibiotics after every abscess after I & D. If antibiotics were given, 33% prescribed trimethoprim-sulfamethoxazole alone, 8% prescribed cephalexin alone, 8% prescribed clindamycin alone, and 47% used a combination of two or more antibiotics (Schmitz, 2013).

In the 1990’s, wound cultures were routinely obtained after abscess I & D given the emergence of CA-MRSA. Current research, however, suggests that the routine practice of obtaining would cultures in uncomplicated cutaneous abscesses is not necessary. An article published in the Annals of Emergency Medicine emphasizes that there is a lack of data to suggest which clinical situations pose a greater chance of treatment failure (for which the addition of antibiotics would be potentially useful) (Abrahamian, 2007). From a cost consciousness perspective, there is no benefit to sending tests that won’t change management. The authors suggest that wound cultures may be reserved for immunocomprimised patients, significant surrounding cellulitis, systemic toxicity, recurrent or multiple abscesses, and those who have previously failed treatment. Even in patients who fail treatment, other scenarios besides inappropriate antibiotic choice may have contributed to the failure, including inadequate I & D, poor wound care, or noncompliance with antibiotic regimen.

Editor’s note: After we completed our “answers,” the New England Journal of Medicine published an excellent expert review article by Drs. Singer (referenced above) and Talan. It covers some of the same ground as our “answers,” as well as some pearls on diagnosis and prevention. Check it out here.