Table 1.
Baseline Characteristics of Participants with a Drained Skin Abscess Treated with Trimethoprim-Sulfamethoxazole or Placebo in the Per-Protocol Population.
| Characteristic | Trimethoprim- sulfamethoxazole (n=524) | Placebo (n=533) |
|---|---|---|
|
| ||
| Median age, years (IQR, range)* | 35 (26–47.5, 14–69) | 35 (26–48, 16–73) |
|
| ||
| Male Sex – n (%) | 303 (57.8) | 308 (57.8) |
|
| ||
| Race – n (%) | ||
| White | 244 (46.6) | 252 (47.3) |
| Black | 232 (44.3) | 233 (43.7) |
| Asian | 5 (1.0) | 2 (0.4) |
| Hawaiian/Pacific Islander | 0 (0.0) | 1 (0.2) |
| American Indian/Alaskan Native | 3 (0.6) | 2 (0.4) |
| Multi-Racial | 22 (4.2) | 22 (4.1) |
| Other/Unknown | 18 (3.4) | 21 (3.9) |
|
| ||
| Hispanic Ethnicity - n (%) | 178 (34.0) | 180 (33.8) |
|
| ||
| Median (IQR) number of days symptoms | 4.0 (3.0–5.0) | 4.0 (3.0–5.0) |
|
| ||
| History of methicillin-resistant Staphylococcus aureus (MRSA) infection | 45 (8.6) | 40 (7.5) |
|
| ||
| Comorbidities† – n (%) | ||
| Cancer | 6 (1.1) | 3 (0.6) |
| CHF | 5 (1.0) | 4 (0.8) |
| COPD | 6 (1.1) | 6 (1.1) |
| Chronic edema | 3 (0.6) | 1 (0.2) |
| Diabetes | 58 (11.1) | 57 (10.7) |
| Eczema | 22 (4.2) | 14 (2.6) |
| HIV+ | 7 (1.3) | 10 (1.9) |
| Any of the above | 92 (17.6) | 88 (16.5) |
|
| ||
| Abscess related to IV drug use – n (%) | 20 (3.8) | 13 (2.4) |
|
| ||
| History of prior antibiotic treatment for skin and soft tissue infection – n (%) | 2 (0.4) | 4 (0.8) |
|
| ||
| Close household contact‡ – n (%) | 37/520 (7.1) | 39/529 (7.4) |
|
| ||
| Fever§ - n (%) | 102/520 (19.6) | 98/528 (18.6) |
|
| ||
| Abscess location – n (%) | ||
| Head/neck | 68 (13.0) | 78 (14.6) |
| Trunk/Abdomen/Back | 116 (22.1) | 108 (20.3) |
| Groin/Buttocks | 113 (21.6) | 102 (19.1) |
| Upper Extremity | 117 (22.3) | 118 (22.1) |
| Lower Extremity | 110 (21.0) | 127 (23.8) |
|
| ||
| Median abscess dimension by probe of abscess cavity, cm (IQR, range) | ||
| Length|| | 2.5 (2.0–3.5,0.5–13.0) | 2.5 (2.0–3.5,0.1–16.0) |
| Width | 2.0 (1.5–3.0,0.3–11.0) | 2.0 (1.5–3.0,0.1–10.0) |
| Depth | 1.5 (1.0–2.0,0.3–5.5) | 1.5 (1.0–2.0, 0.1–5.0) |
|
| ||
| Abscess cavity maximal dimension|| ≥ 5 cm – n (%) | 78/523 (14.9) | 72/533 (13.5) |
|
| ||
| Median erythema dimension, cm (IQR, range) | ||
| Length | 6.8 (4.5–10.0,1.0–32.0) | 6.5 (4.0–10.0,2.0–38.5) |
| Width | 5.0 (3.2–8.0,1.0–40.0) | 5.0 (3.4–8.0,1.0–28.5) |
| Area||¶ | 19.7 (7.0–54.4,0.0–582.8) | 21.2 (7.1–55.4,0.0–520.9) |
|
| ||
| Area|| of erythema >75 cm2 – n (%) | 107 (20.4) | 110 (20.6) |
|
| ||
| Erythema maximal dimension|| ≥ 5 cm – n (%) | 390 (74.4) | 399 (74.9) |
|
| ||
| Median dimensions of induration/swelling, cm (IQR, range) | ||
| Length | 4.5 (3.5–6.5,1.0–19.0) | 4.5 (3.2–6.0,0.5–20.0) |
| Width | 4.0 (3.0–5.0,1.0–16.0) | 4.0 (3.0–5.0,0.9–29.0) |
| Area¶ | 7.5 (2.8–18.3,0.0–198.5) | 8.2 (2.8–18.1,0.0–396.6) |
|
| ||
| Baseline wound culture results | ||
| Methicillin-resistant Staphylococcus aureus | 219 (41.8) | 249 (46.7) |
| Methicillin-susceptible S. aureus | 86 (16.4) | 86 (16.1) |
| Coagulase-negative staphylococci | 68 (13.0) | 59 (11.1) |
| Streptococcal species** | 36 (6.9) | 14 (2.6) |
| Other# | 87 (16.6) | 63 (11.8) |
| No growth | 80 (15.3) | 93 (17.4) |
| Not done | 3 (0.6) | 3 (0.6) |
Participants with missing data were excluded from relevant analyses.
Eight (0.8%) participants were age 13 to 17 years.
Co-morbidities were those present in >0.5%.
A close household contact was defined as someone living in the same household with similar skin infection in last month.
Fever was defined as patient report of history of fever in prior week or temperature >38°C in the ED.
Largest measurement of length or width was defined as the maximal dimension.
Areas of erythema and induration/swelling were calculated using formula for an ellipse (1/4 x πx length x width) minus area of probe measurements of length and width of abscess area.
Streptococcal species included: Group A streptococcus, Group B streptococcus, S. anginosus, beta-hemolytic group C streptococcus, beta-hemolytic group F streptococcus, beta-hemolytic group G streptococcus, Non-group A and B beta-hemolytic streptococcus, Viridans group streptococcus, and Alpha-hemolytic streptococcus.
Other isolates included: Actinomyces species, Bacteroides species, Diphtheroid bacilli, Eikenella corrodens, Enterobacter species, Enterococcus species, Escherichia coli, Fusobacterium species, Haemophilus species, Klebsiella species, Lactobacillus species, Peptostreptococcus species, Porphyromonas species, Prevotella species, Proteus mirabilis, and Veillonella species.