Cellulitis and Abscess Management in the Era of Resistance to Antibiotics (CAMERA)


In the United States, Staphylococcus aureus is the most common cause of skin and soft tissue infections (SSTIs).1 Methicillin resistance, which first emerged more than four decades ago among seriously ill patients in health care settings,2 has now become common. In 2006, the Centers for Disease Control and Prevention (CDC) released clinical recommendations for the management of community-acquired methicillin-resistant Staphylococcus aureus (CA-MRSA).3 These recommendations highlighted the importance of:

  • Considering MRSA in the differential diagnosis for all skin abscesses.
  • Incising and draining abscesses.
  • Using culture results and antimicrobial sensitivity to guide antibiotic treatment.
  • Educating patients to limit the spread of CA-MRSA and to ensure close followup for those patients who do not improve.

Primary care providers play a central role in providing care to individuals with SSTIs. Barriers to following the CDC recommendations could include factors related to the physician (e.g., lack of awareness about the CDC recommendations, lack of training in incision and drainage [I&D]), practice organizational characteristics (e.g., lack of time, lack of reimbursement, practice stress and chaos), and patient characteristics (e.g., health status and likelihood of CA-MRSA infections, access to health care).

Employing a best practices research4 approach, we identified several factors that could improve the delivery of care for patients with SSTIs. These included:

  • A detailed description of the infection in the medical record.
  • I&D with culture, when indicated.
  • Documentation of culture result in the medical record when a culture is obtained.
  • Documented use of antibiotics and rationale for the choice (e.g., presumed CA-MRSA, need to cover another organism such as Streptococcus).
  • Patient education, including wound care, hygiene, and indications for followup with documentation of such patient indication in the medical record.

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Study Goals

The overarching goals of this study were to identify and disseminate effective, feasible, and sustainable strategies for the diagnosis and management of CA-MRSA in the primary care practice setting. The specific objectives were:

  1. To develop tools to assist primary care providers in identifying and managing SSTIs that may be caused by CA-MRSA and field test the tools in a sample of nine primary care practices.
  2. To assess the effectiveness of the bundle of tools within the sample of nine primary care practices.
  3. To characterize the barriers to and facilitators of implementation of the bundle of tools.
  4. To disseminate feasible and sustainable practice-level tools based on the findings within the sample of nine primary care practices.

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Overview of Study Interventions

At the start of the project, we developed three tools: the Skin and Soft Tissue Infection Action Plan (Appendix A), the Skin and Soft Tissue Culture Kit (Appendix B), and the Skin and Soft Tissue Patient Information Material (Appendix C). The action plan was a document to assist providers in recording all elements recommended by the CDC in the management of a patient with a SSTI, including appearance, the need for I&D, whether a culture was obtained, and the initial antibiotic choice (if any), along with the rationale for the choice. Practices could modify the action plan to fit their work flow (e.g., specific chart layout, modification as a template for an electronic medical record [EMR]). The culture kit fulfills our recommendation that each practice organize the materials required for I&D. Having this kit reduces the time it takes to gather supplies, which we have found to be a barrier to other procedures, and ensures the practice has the appropriate tools to perform I&D when needed. The patient information material consisted of a range of printed material (e.g., posters produced by the CDC, general information sheets about SSTIs).

We developed a 45-minute PowerPoint training presentation (Appendix D, available at http://www.ahrq.gov/qual/mrsa/nc_mrsaapdpt1.ppt; PowerPoint® 11 MB; Plugin Software Help) on SSTIs that provided practical management advice and engaged practitioners to think about how to improve clinical care for patients with SSTIs. This presentation included CDC materials. During the training presentation, we also introduced the tools and solicited advice about how they could be modified to fit with the practice flow.

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Study Setting

This project was conducted by NCNC, a statewide consortium of primary care practices and academic institutions. Two of the NCNC practice-based research networks participated in this project: the Duke Primary Care Research Consortium (PCRC) and the Robeson County Primary Care Network (RCPCN). The PCRC is the academic home of the principal investigator and includes practices in Chapel Hill, Durham, and Raleigh, NC. The RCPCN includes practices in rural North Carolina and includes many patients who identify themselves as American Indians.

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Participating Practices

Nine primary care practices were selected from NCNC (Table 1). Of these, five were primary care pediatric practices and four were internal medicine practices. Most practices were located either in rural areas or small cities. The median number of physicians was 7 (range 1 to 11) in the pediatric practices and 1.5 (range 1 to 5) in the internal medicine practices. Three (60 percent) of the pediatric practices and two (50 percent) of the internal medicine practices used physician extenders (e.g., nurse practitioners, physician assistants). Three (60 percent) of the pediatric practices and one (25 percent) of the internal medicine practices used an EMR to document patient encounters.

Table 1. Characteristics of participating practices

Type Location Number of
Number of
Physician Extenders
Medical Record
1 Pediatric Small City 7 1 No
2 Pediatric Small City 7 0 No
3 Pediatric Small City 8 0 Yes
4 Pediatric Rural 11 5 Yes
5 Pediatric Rural 1 4 Yes
6 Internal Medicine Small City 2 0 No
7 Internal Medicine Large City 5 1 Yes
8 Internal Medicine Rural 1 1 No
9 Internal Medicine Rural 1 0 No

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Human Subjects Protection and Subject Followup

The Institutional Review Boards of the Duke University Medical Center and at the University of North Carolina, Chapel Hill, approved this practice-level intervention study. Because patients within the practices did not provide consent to be contacted, the research team was unable to contact individuals to follow up on the outcomes of treatment. Since monitoring the results of treatment is a recommended part of routine care, we developed a patient diary that would provide feedback to the practice on outcomes of treatment. This form (Appendix E), which was designed to be part of the medical record, could both improve care and serve as a method for the research team to quantify outcomes. However, few patients returned these forms. No analysis of these forms is therefore presented. We did collect and analyze follow-up information for the month after diagnosis of the index infection from the participating practices.

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Study Measures

The primary source of data for this project came from chart audits of patients treated with suspected SSTIs. We audited up to 30 charts per month from each practice. The chart audit instrument appears in Appendix F.

Charts were identified based on the encounter billing data. Although we were primarily interested in the management of abscesses, we sampled all charts for which any significant SSTI was included in the diagnosis claims. We also sampled charts that included claims for incision and drainage. Charts were audited at least 1 month after the initial encounter. This allowed for entry into billing systems for identification and for short-term followup of the SSTI.

The International Classification of Diseases, 9th Revision (ICD-9) codes were:

  • 041.1, Staphylococcus infection
  • 680.X, Carbuncle and furuncle
  • 681.X, Cellulitis and abscess of finger and toe
  • 682.X, Other cellulites and abscess
  • 684.X, Impetigo
  • 685.X, Pilonidal cyst
  • 686.X, Other infections of skin and subcutaneous tissue

The Current Procedural Terminology (CPT®) codes were:

  • 10060, I&D of abscess (single or simple)
  • 10061, I&D of abscess complicated or multiple
  • 10080, I&D of pilonidal cyst (single)
  • 10081, I&D of pilonidal cyst (complicated)
  • 10160, Puncture aspiration of abscess, hematoma, bulla, or cyst

The research team collected their experiences and observations in field notes during the interventions with the practices. These qualitative experiences became central to understanding the project findings.

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Practice Duration of Enrollment

The study intervention period for each practice began after the practice presentation. We collected data from up to 3 preceding months (equivalent to up to 90 chart audits) covering the period before the start of the intervention. Practices could participate in the intervention period for up to 12 months, with up to 30 chart audits per month. Because of the rolling start date for participation, practices participated for a variable amount of time in the project. The period of practice enrollment is illustrated in Table 2. The median number of months of participation was 9 (range 8 to 12) for the pediatric practices and 8 (range 6 to 12) for the internal medicine practices.

Table 2. Duration of practice enrollment

Practice Type Project Month
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16
1 Pediatric   X O O O O O O O O O O O      
2 Pediatric X O O O O O O O O O O O        
3 Pediatric             X O O O O O O O O  
4 Pediatric             X O O O O O O O    
5 Pediatric             X O O O O O O O    
6 Internal Medicine   X O O O O O O O O O O O      
7 Internal Medicine             X O O O O O O O O O
8 Internal Medicine             X O O O O O        
9 Internal Medicine             X O O O O O        

Key: Eligible patient visits for the chart audit began in February 2009 (labeled as Project Month 1) and finished in June 2010 (labeled as Project Month 16). “X” indicates the month of the practice presentation and “O” indicates the subsequent months in which the practice participated.

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Barriers to Practice Participation

Three factors decreased practice participation: The H1N1 influenza outbreak, staff turnover, and inability to identify potential cases.

The H1N1 influenza outbreak diminished interest in MRSA. At the start of the project, providers considered MRSA to be an important cause of morbidity in their practice; however, interest rapidly switched to concern about H1N1. Our research team was regularly asked advice about management of H1N1.

Because one practice (practice 7) had significant physician and office staff turnover, there was no memory within the practice of the initial presentation or the project's goals. Practice chaos precluded active engagement in the project. However, because the practice used an EMR, we were able to continue with monthly chart audits.

Finally, two practices (practices 8 and 9) had difficulty in identifying potential cases from their billing systems, leading to time periods before charts could be abstracted. These practices were therefore unable to provide data for a 12-month intervention period.

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Findings are categorized by those related to diagnosis and those related to treatment and outcomes. Field notes are used to clarify quantitative findings.


We found significant variations in the use of CPT codes to identify SSTIs, with no clear pattern related to the chart note. The notes describing encounters often lacked specificity in describing lesions, including whether an abscess was present. Similarly, the ICD-9 codes were used inconsistently. Practices had little knowledge about these codes. This was surprising because I&D is usually a reimbursable procedure when the proper billing codes are used. One practice (practice 8) was aware of the ICD-9 codes but did not realize until our review that the codes were not being processed within its internal billing system, leading to loss of revenue.

Practices were inconsistent in using the Skin and Soft Tissue Infection Action Plan note. However, one practice (practice 1) reported that the action plan was helpful in improving documentation. All four practices that used EMRs expressed interest in converting the action plan into a template for their systems. However, despite their interest, none of the practices were able to do so because the process of generating a new template was more difficult than initially thought. These practices lacked the information technology support to produce new templates.

Because the word “abscess” was often not used in the medical record, we classified lesions as an abscess if they were >1 cm. in diameter and painful or tender, or were fluctuant or indurated. This definition was developed to maximize specificity in classification. Overall, there were 498 patients with abscesses based on this definition included in this study. Table 3 summarizes the total number of patients with abscesses among the total number of chart audits, all with SSTIs.

Abscess Treatment

At the start of the project, many providers reported that there was insufficient time to perform I&D and that reimbursement was not sufficient to justify the time. Many reported that they instead would routinely refer patients to a local surgeon, urgent care clinic, or emergency department. There were many questions about how to perform I&D. One practice reported that it would manually express abscesses to force them to drain. Manual expression was poorly documented in charts; it was often difficult to determine whether the abscess was already draining. Overall, 26 percent of patients were documented to have been treated with I&D, 4 percent by needle aspiration, 21 percent by manual expression, and 49 percent had no documented abscess drainage. However, all practices reported that they routinely refer patients for I&D based on patient factors (e.g., size, location, age) and practice factors (e.g., training and experience, business schedule). Of those categorized as having an abscess, 52 percent (n=259) were documented to have been cultured. Table 4 shows the number of abscesses that were cultured based on method of drainage.

Table 4. Proportion with culture by treatment

Treatment Proportion With Culture
I&D 90%
Needle aspiration 89%
Manual expression 82%
No documented drainage 16%

Among those who had an abscess and were cultured, 56 percent (162) were documented to have MRSA, 10 percent (28) had Staphylococcus aureus without specification of methicillin resistance, 5 percent (15) had methicillin-sensitive Staphylococcus aureus, 10 percent (29) had skin flora or mixed culture results, 10 percent (29) had negative culture results, 3 percent (8) had a culture positive for a streptococcal species, and 6 percent (16) had a culture positive for another organism (e.g., Klebsiella, Proteus mirabilis). In only four cases was a culture indicated as obtained with no documentation of result.

All but 27 (5 percent) of those with an abscess were treated with an oral or topical antibiotic. These are listed in Table 5. Antibiotic treatment nearly always covered MRSA.

Of the 47 patients with an abscess who were not treated with an oral antibiotic that could potentially treat a MRSA infection, 33 (70 percent) were not cultured. Six of those with no documented drainage required follow-up office visits, one of whom subsequently underwent I&D. Issues related to followup are further described in the next section.

Practice Followup

Table 6 summarizes the proportion of individuals who had followup after the diagnosis of abscess or other skin or soft tissue infection by practice within 14 days. There was no statistically significant difference in the rate of followup for those with abscesses between the pediatric and internal medicine practices (36 percent versus 39 percent, p=0.63). Among those with other SSTIs, the rate of followup was lower among the pediatric clinics compared to the internal medicine clinics (16 percent versus 29 percent, p<0.001). The median number of follow-up visits was one, regardless of practice type or whether the initial infection was an abscess or other SSTI.

Table 6. Rates of followup within each practice after the diagnosis of an abscess or other skin or soft tissue infection

Practice Type Abscesses
% (n)
Other Skin or Soft
Tissue Infections
% (n)
1 Pediatric 92 17% (16) 344 6% (22)
2 Pediatric 42 38% (16) 196 14% (27)
3 Pediatric 35 29% (10) 191 12% (23)
4 Pediatric 148 51% (75) 210 31% (66)
5 Pediatric 109 33% (36) 219 21% (46)
6 Internal Medicine 9 67% (6) 78 45% (35)
7 Internal Medicine 6 17% (1) 74 23% (17)
8 Internal Medicine 28 32% (9) 34 12% (4)
9 Internal Medicine 29 41% (9) 28 25% (7)
Total   498 181 (36%) 1,374 18% (247)

Among those with an abscess, 12 percent (57) required a change in antibiotic. The rate was lower (6 percent, n=77) among those with other SSTIs (p<0.001). Nearly all of these changes involved expanding coverage for MRSA. None of the patients diagnosed with a SSTI not classified as an abscess required care in an emergency department or urgent care setting. Among those with an abscess, 5 percent (24) were documented to have required emergency department or urgent care, including 21 (12 percent) of those who had at least one follow-up visit and 3 (1 percent) who had no follow-up visits. Among those with an abscess, 6 percent (27 out of 452) required hospitalization compared to 2 percent without an abscess (28 out of 1,277). Rates of hospitalization did not vary between the pediatric and internal medicine practices (p>0.79).

There was no difference in the likelihood of emergency department or urgent care followup or hospitalization by sex (p=0.96). The rate did vary by age (p<0.001) as described in Table 7. Overall, the highest rate was among the youngest children. However, there was significant fluctuation, likely due to the sample size. These results are not adjusted for clustering by clinic site due to sample size constraints.

Table 7. Rate of emergency department or urgent care followup or hospitalization by age

Age Sample Size Rate
4 years 577 8%
4-12 years 636 1%
13-20 years 378 5%
21-40 years 66 2%
40-64 years 130 7%
≥ 65 years 85 4%

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Page last reviewed October 2014
Page originally created September 2012
Internet Citation: Introduction. Content last reviewed October 2014. Agency for Healthcare Research and Quality, Rockville, MD. http://www.ahrq.gov/research/findings/final-reports/mrsa/nc_mrsa1.html