Effectiveness of Type I Collagen Matrix Plus Polyhexamethylene Biguanide Antimicrobial for the Treatment of Pressure Injuries

Michael J. Menack, MD; Kerry T. Thibodeaux, MD; Carlos Trabanco, MD; Michael Leon Sabolinski, MD


Wounds. 2022;34(6):159-164. 

In This Article

Abstract and Introduction


Introduction: The first prospective noninterventional registry study (RESPOND) evaluated the clinical effectiveness of a native type I collagen matrix plus polyhexamethylene biguanide antimicrobial barrier (PCMP) in various nonhealing wounds. This product is intended for the management of partial- and full-thickness wounds and acts as an effective barrier to reduce microbes penetrating through the dressing. The RESPOND study demonstrated that PCMP has clinically meaningful benefits in managing a variety of wounds.

Objective: The authors describe the effects of PCMP in the subgroup of patients with pressure injuries (PIs) from the RESPOND registry.

Materials and Methods: The prospective, noninterventional study was designed to collect information regarding the use of PCMP in a real-world situation. Eligibility included male and female patients aged 18 years and older with target wounds (partial- or full-thickness) suitable for the use of PCMP. Enrolled patients were followed approximately weekly for up to 32 weeks. All wounds and the subgroups were analyzed to determine the frequency and median time to wound closure using Kaplan-Meier methods.

Results: The patients with PIs were older adults with a mean age of 69 years and a mean BMI of 27 kg/m2. At baseline, the mean measured wound length was 3 cm, the mean depth was 8.0 mm, the mean volume was 12.6 cm3, and the mean area was 10.5 cm2. Complete wound closures were evident in 5% of patients (n = 2) at week 4, and were achieved in 39% of patients (n = 18) by week 16, in 49% (n = 22) by week 24, and in 62% (n = 28) by week 32. The median time to wound closure was 32 weeks. For all 45 PIs managed with PCMP, the incidence of achieving greater than 60% reduction in baseline area and depth was 78% (n = 35) and 64% (n = 29), respectively, with approximately 82% (n = 37) of wounds showing a reduction in volume greater than 75%.

Conclusions: It appears that PCMP is a useful adjunct in managing chronic deep wounds such as PIs.


Normal wound healing involves a series of phases that includes hemostasis, inflammation, proliferation, and remodeling. In chronic wounds, the healing process is often arrested in the inflammatory phase. This phase is characterized by increased levels of inflammatory mediators and matrix metalloproteinases (MMPs), which damage growth factors and the extracellular matrix (ECM) that are required for wound healing. These wounds are superficially colonized with high levels of bacteria that stimulate the immune cells to release proteolytic enzymes that damage the ECM. The formation of a polymicrobial biofilm supports the excessive bacterial bioburden, which is considered the primary cause of a prolonged inflammatory response and delayed healing.[1,2] Microbes associated with the biofilm produce an extracellular polymeric substance composed of a very dense collection of proteins, sugars, and other factors that acts as a protective layer to impair diffusion of inflammatory cells (eg, neutrophils and macrophages) as well as antibodies and antibiotics.[3]

Pressure injuries (PIs) are chronic cutaneous wounds localized to the skin or underlying tissues over a bony prominence. They are the result of sustained pressure or pressure in combination with shear and/or tissue deformation and affect more than 2.5 million individuals in the United States annually.[4,5] Populations at highest risk for the development of PIs include elderly people; those in critical care, palliative care, community care, or rehabilitation settings; those with spinal cord injury or obesity; and neonates and children. In general, these individuals are sedentary and have multiple comorbidities. Overall, the highest rates of PIs are reported in critically ill patients in hospitals.[4] The prevalence of PI varies from approximately 9% to 32% in long-term care facilities and from 3% to 19% in patients in home care, with most of these lesions categorized as stage 1 and stage 2.[6–9] The National Pressure Injury Advisory Panel (NPIAP) staging criteria were applied in the study. Briefly, stage 1 is defined by intact skin with a localized area of nonblanchable erythema. Stage 2 is defined by partial-thickness loss of skin with exposed dermis. Stage 3 is characterized by full-thickness loss of skin, in which adipose (fat) is visible in the ulcer and granulation tissue and epibole (rolled wound edges) are often present. Stage 4 shows full-thickness skin and tissue loss with exposed or directly palpable fascia, muscle, tendon, ligament, cartilage, or bone.[10]

Like most chronic wounds, PIs are associated with the formation of a biofilm.[4] In general, management of the biofilm is considered essential in wound management. Two approaches are surface debridement and antimicrobial therapies. Although surface debridement effectively removes the biofilm, a new biofilm can rapidly re-form within 24 hours and mature in 3 days.[11–14] Thus, current guidelines for biofilm-based wound care recommend debridement in combination with topical antiseptic agents to reduce the bacterial counts and prevent biofilm reformation.

Topical or systematic antibiotics, or a combination of both, may be effective antimicrobial agents, but they primarily work against metabolically active bacteria and do not work against the many microbes within a biofilm that are metabolically inactive.[1] Some antimicrobial agents may be effective at controlling the bioburden, but they may be deleterious to normal cells. Polyhexamethylene biguanide (PHMB) is a positively charged broad-spectrum antimicrobial agent capable of binding to the bacterial cell walls and membranes; it has broad antimicrobial activity without microbial resistance, with low microbial tolerance, and with no cytotoxic effects.[15,16] Additionally, topically applied PHMB is not systemically absorbed through the skin or wounds.

Native collagen dressings are used as a skin substitute in wound care to mimic the natural environment for tissue remodeling by allowing for the migration of fibroblasts and keratinocytes to encourage new collagen growth at the wound bed.[17,18] Collagen dressings can also bind and reduce the activity of excess MMPs present in the ECM that prohibit wound healing.[19] PuraPly AM (Organogenesis, Inc) is a construct of a purified native type I collagen ECM plus PHMB antimicrobial (referred to as PCMP hereafter) that is intended for wound management.[20] This is a US Food and Drug Administration class II medical device that has received 510(k) clearance (#K051647).[20,21] The postmarket, open-label, prospective, observational, multicenter registry study, Real-World Effectiveness Study of PuraPly AM on Wounds (RESPOND), was conducted to examine the use of PCMP in wound treatment in the clinical setting.[22,23] This study included 307 patients with venous leg ulcers (VLUs), diabetic foot ulcers (DFUs), PIs, postoperative wounds, and other wounds.[23] Most of the wounds in this study were classified as chronic. The results demonstrated PCMP to be clinically beneficial in the treatment of various types of cutaneous wounds and showed favorable overall wound closure rates associated with substantial reductions in wound area (81%), depth (71%), and volume (85%).

A detailed subgroup analysis of the effectiveness of PCMP in the 45 patients with PIs who participated in the RESPOND registry trial is presented in the current study.