Recurrent skin and soft tissue infections in HIV-infected patients during a 5-year period: incidence and risk factors in a retrospective cohort study.
BACKGROUND
Skin and soft tissue infections (SSTIs) are common in the era of community-associated methicillin resistant Staphylococcus aureus among HIV-infected patients. Recurrent infections are frequent. Risk factors for recurrence after an initial SSTI have not been well-studied.


METHODS
Retrospective cohort study, single center, 2005-2009. Paper and electronic medical records were reviewed by one of several physicians. Subjects with initial SSTI were followed until the time of SSTI recurrence. Standard descriptive statistics were calculated to describe the characteristics of subjects who did and did not develop a recurrent SSTI. Kaplan-Meier methods were used to estimate the risk of recurrent SSTI. A Cox regression model was developed to identify predictors of SSTI recurrence.


RESULTS
133 SSTIs occurred in 87 individuals. 85 subjects were followed after their initial SSTI, of whom 30 (35.3 %) had a recurrent SSTI in 118.3 person-years of follow-up, for an incidence of second SSTI of 253.6 SSTIs/1000 person-years (95 % CI 166.8-385.7). The 1-year Kaplan-Meier estimated risk of a second SSTI was 29.2 % (95 % CI 20.3-41.0 %), while the 3-year risk was 47.0 % (95 % CI 34.4-61.6 %). Risk factors for recurrent SSTI in a multivariable Cox regression model were non-hepatitis liver disease (HR 3.44; 95 % CI 1.02-11.5; p = 0.05), the presence of an intravenous catheter (HR 6.50; 95 % CI 1.47-28.7; p = 0.01), and a history of intravenous drug use (IVDU) (HR 2.80; 95 % CI 1.02-7.65; p = 0.05); African-American race was associated with decreased risk of recurrent SSTI (HR 0.12; 95 % CI 0.04-0.41; p < 0.01). Some evidence was present for HIV viral load ≥ 1000 copies/mL as an independent risk factor for recurrent SSTI (HR 2.21; 95 % CI 0.99-4.94; p = 0.05). Hemodialysis, currently taking HAART, CD4+ count, trimethoprim-sulfamethoxazole or azithromycin use, initial SSTI type, diabetes mellitus, incision and drainage of the original SSTI, or self-report of being a man who has sex with men were not associated with recurrence.


CONCLUSIONS
Of HIV-infected patients with an SSTI, nearly 1/3 had a recurrent SSTI within 1 year. Risk factors for recurrent SSTI were non-hepatitis liver disease, intravenous catheter presence, a history of IVDU, and non-African-American race. Low CD4+ count was not a significant risk factor for recurrence.
Division of Infectious Diseases, Department of Medicine, Baylor College of Medicine, 6620 Main, Suite 1375, Houston, TX, 77030, USA. vagish.hemmige@bcm.edu.
Vagish
V
Hemmige
Department of Medicine, University of Chicago, 5841 S Maryland, Chicago, IL, 60637, USA. moira.mcnulty@uchospitals.edu.
Moira
M
McNulty
Department of Medicine, University of Chicago, 5841 S Maryland, Chicago, IL, 60637, USA. ejsilve@gmail.com.
Ethan
E
Silverman
Department of Medicine, University of Chicago, 5841 S Maryland, Chicago, IL, 60637, USA. mdavid@medicine.bsd.uchicago.edu.|Department of Pediatrics and Department of Public Health Sciences, University of Chicago, 5841 S. Maryland Ave. MC6054, Chicago, 60637, IL, USA. mdavid@medicine.bsd.uchicago.edu.
Michael Z
MZ
David
D000328:Adult; D023241:Antiretroviral Therapy, Highly Active; D017963:Azithromycin / Q000627:therapeutic use; D018791:CD4 Lymphocyte Count; D015331:Cohort Studies; D060085:Coinfection / Q000188:drug therapy; D005260:Female; D015658:HIV Infections / Q000188:drug therapy / Q000382:microbiology*; D006801:Humans; D053208:Kaplan-Meier Estimate; D008297:Male; D055624:Methicillin-Resistant Staphylococcus aureus / Q000472:pathogenicity; D008875:Middle Aged; D012189:Retrospective Studies; D012307:Risk Factors; D018461:Soft Tissue Infections / Q000453:epidemiology* / Q000382:microbiology; D013207:Staphylococcal Skin Infections / Q000453:epidemiology*; D015819:Substance Abuse, Intravenous / Q000150:complications; D015662:Trimethoprim, Sulfamethoxazole Drug Combination / Q000627:therapeutic use
D015662:Trimethoprim, Sulfamethoxazole Drug Combination; D017963:Azithromycin