Granzyme B mediates impaired healing of pressure injuries in aged skin.

Pressure injuries (PIs), also known as bedsores or pressure ulcers, are a major cause of death and morbidity in the elderly. The serine protease, Granzyme B (GzmB), contributes to skin aging and impaired wound healing. Aging is a major risk factor for PIs; thus, the role of GzmB in PI pathogenesis was investigated. GzmB levels in human PI tissue and wound fluids were markedly elevated. A causative role for GzmB was assessed in GzmB knockout (GzmB-/-) and wild-type (WT) mice using a murine model of PI. An apolipoprotein E knockout (ApoE-/-) model of aging and vascular dysfunction was also utilized to assess GzmB in a relevant age-related model better resembling tissue perfusion in the elderly. PI severity displayed no difference between young GzmB-/- and WT mice. However, in aged mice, PI severity was reduced in mice lacking GzmB. Mechanistically, GzmB increased vascular wall inflammation and impaired extracellular matrix remodeling. Together, GzmB is an important contributor to age-dependent impaired PI healing.

Frequency and yield of blood cultures for observation patients with skin and soft tissue infections.

OBJECTIVES: 1) To measure frequency and yield of blood cultures obtained for observation status adult patients with skin and soft tissue infection (SSTI), 2) describe how often blood cultures were performed according to Infectious Diseases Society of America (IDSA) SSTI guideline indications, 3) identify proportion of patients meeting Center for Medicare Services (CMS) sepsis criteria. DESIGN: Retrospective cohort. SETTING: Tertiary academic center. PATIENTS: Consecutive adult observation status patients hospitalized with SSTI between July 2017 and July 2018. METHODS: We measured the proportion and results of blood cultures obtained among the study cohort and proportion of obtained cultures that satisfied IDSA indications. RESULTS: We identified 132 observation status patients with SSTI during the study period; 67 (50.8%) had blood cultures drawn. Only 14 (10.6%) patients met IDSA indications for culture; 51 (38.%) met Center for Medicare Services definition for sepsis. We identified two (3.0%) cases of bacteremia and two (3.0%) cases of skin bacteria contamination. In multivariable analysis, only temperature > 38 °C (OR 3.84, 95%CI 1.09-13.60) and white race (OR 2.71, 95%CI 1.21-6.20) were associated with blood culture obtainment; neither meeting IDSA SSTI guideline indications nor meeting CMS sepsis criteria was associated with culture. CONCLUSIONS: Among observation status patients with SSTI, over half had blood cultures drawn, though 10% satisfied guideline indications for culture. The proportion of cultures with bacterial growth was low and yielded as many skin contaminants as cases of bacteremia. Our study highlights the need for further quality improvement efforts to reduce unnecessary blood cultures in routine SSTI cases.