Randomized, Double-Blind, Placebo-Controlled Trial of Cephalexin for Treatment of Uncomplicated Skin Abscesses in a Population at Risk for Community-Acquired Methicillin-Resistant Staphylococcus aureus Infection

DOI: 10.1128/AAC.00377-07

Article Figures & Data

TABLE 1.

Baseline characteristics of the 166 study subjects included in the analyses, by study group

Characteristic	Value for study group:		P value
Characteristic	Cephalexin	Placebo	P value
Age, median (range), yr	43 (22-66)	45 (22-88)	0.3191
Male sex (%)	72.0	81.0	0.2313
Race (%)			0.2431
American Indian	6.2	0
Pacific Islander	1.5	1.5
Asian	4.6	1.5
African-American	38.5	46.2
Caucasian	49.2	50.8
Homeless (%)	35.4	38.1	0.7493
Diabetes (%)	2.4	6.0	0.4432
Hepatitis B or C (%)	30.5	33.3	0.7408
HIV infection (%)	15.9	7.1	0.0915
Abscess size of >5 cm in dimension (%)
Length	17.7	18.1	1.0000
Width	19.2	24.1	0.5668
Depth	1.4	5.3	0.3678
Surface area, mean (range), cm²	18.7 (1-144)	19.0 (1-150)	0.3676
Tissue depth (%)
Subcutaneous	64.1	67.7	0.9048
Fascia	17.2	14.1
Muscle	18.8	18.3
Underlying skin disease (%)
Folliculitis	38.8	40.2	1.0000
Atopic dermatitis	0.05	0.01	1.0000

TABLE 2.

Reasons for clinical failures by study group

Reason	No. of subjects in study group:
Reason	Cephalexin (n = 13)	Placebo (n = 8)
Nurse practitioner thought abscess was not healing as expected	8	3
Patient was prescribed antibiotics for new, nonadjacent abscess	0	2
Patient returned to emergency department complaining of worsening abscess	2	0
Patient started on antibiotics for unrelated medical condition during study period	0	1
Primary care provider urged patient to withdraw from study due to HIV infection	1	0
Loss to follow-up	2	2

TABLE 3.

Characteristics of the 166 subjects, by clinical outcome

TABLE 4.

Pathogen distribution by study group

Organism	No. (%) of subjects by study group:
Organism	Cephalexin (n = 80)	Placebo (n = 82)
Staphylococcus aureus only	55 (68.8)	55 (67.1)
Streptococcus species only	2 (2.5)	5 (6.1)
Both Staphylococcus aureus and Streptococcus species	3 (3.8)	1 (1.2)
Neither species	20 (25.3)	21 (25.6)

TABLE 5.

Antimicrobial susceptibilities of Staphylococcus aureus from abscesses at enrollment, by study group^a

Antimicrobial agent	No. (%) of isolates for study group:
Antimicrobial agent	Cephalexin (n = 50)	Placebo (n = 49)
Nafcillin	6 (12.0)	6 (12.2)
Erythromycin	8 (16)	7 (14.3)
Ciprofloxacin	25 (50.0)	30 (61.2)
Levofloxacin	27 (74.0)	39 (79.6)
Tetracycline	39 (88.0)	41 (83.7)
Clindamycin	44 (88.0)	44 (89.8)
Rifampin	49 (98.0)	49 (100)
Gentamicin	50 (100)	49 (100)
Trimethoprim-sulfamethazole	50 (100)	49 (100)
Vancomycin	50 (100)	49 (100)
Linezolid	50 (100)	40 (100)

↵ a Of the 110 staphylococcal isolates, antimicrobial susceptibility data were available for 99.

TABLE 6.

Prevalence and cure rates of PVL-producing MRSA, by study group