Response to “Bacterial Fluorescence Imaging to Address Racial Inequities in Wound Infection Assessment”

I read with interest the article “Bacterial Fluorescence Imaging to Address Racial Inequities in Wound Infection Assessment” by Andersen et al. The authors accurately notice that erythema due to infection may not be visible in dark-skinned people. They correctly state that antimicrobial usage is often inappropriate, which is also true as up to 71% of wound care patients receive antimicrobials inappropriately.1 However, I disagree with the authors’ conclusion that bacterial fluorescent imaging technology is required to transform wound assessment and their recommendation that the use of MolecuLight become the standard of point of care among wound care practitioners. Andersen et al use a new term, “chronic inhibitory bacterial load (CIBL).” Terms such as “chronic inhibitory bacterial load,” “critical bacterial colonization,” and “bacterial colonization” create a terminology soup leading to confusion among wound care practitioners. The authors define CIBL as “pathologic bacteria that prevent healing and increase infection risk.” However, the term does not include a myriad of nonpathogenic bacteria, so-called commensals, that inhabit chronic wounds as well.2 Some wound commensals may also lead to a decrease in wound healing trajectories, and some can become pathogenic in hosts with decreased immune systems.3 The biggest fallacy of wound debridement using fluorescent imaging proposed by Andersen et al is the indiscriminate killing of all wound bacteria, potential pathogens, and commensals. The surgical approach of “cutting out” the problem undermines the concept that chronic wounds are polymicrobial living organisms creating a microbiota with complex interactions between its members and the host. Many wound commensals protect the wounds from pathogens by competing for space and resources, producing antimicrobial compounds, or upregulating the host immune system.2,4 MolecuLight does not differentiate between pathogens and commensals. Indiscriminate killing of protective commensal flora inevitably leads to wound colonization with aggressive and/or multidrug-resistant (MDR) pathogens. A lot of research is currently being done on the purposeful colonization of wounds with commensal bacteria. The new chapter in wound care is going to be the development of wound microbiota transplants (similar to colonic and vaginal microbiota transplants aimed to treat Clostridium difficile infection and bacterial vaginal dysbacteriosis), where wounds are purposefully colonized with commensals protecting them from pathogens leading to infections. In Case 1, the sacral wound did not look clinically infected, and antimicrobial treatment was not warranted. Mild periwound erythema and scarring described by the authors were likely inflammatory in nature and related to wound base necrosis, a well-known clinical phenomenon. While it can mimic infection, it typically resolves after the removal of necrotic tissue and without any additional antimicrobial treatment (Figure).Figure: INFLAMMATORY PERIWOUND ERYTHEMA OF THE NECROTIC LEG WOUND RESOLVED WITHOUT ANTIMICROBIALS A WEEK AFTER DEBRIDEMENT, AND THE WOUND HEALED WITHIN A MONTH.The authors used Doxycycline to control “the persistent bacterial contamination.” The notion that antibiotics can be used to control bacterial wound contamination is a dangerous antimicrobial practice that contradicts good antimicrobial stewardship. Doxycycline is a narrow-spectrum antimicrobial that can eliminate protective Gram-positive commensals (eg, Staphylococcus epidermidis and Corynebacterium spp.) and lead to the preselection of Gram-negative pathogens (including Pseudomonas), Enterococcal species, and anaerobes, all of which are abundant in the sacral area. Doxycycline administration would have not only led to the microbiota change in the sacral wound, but it would have also affected the microbiota of the ischial pressure injury. All three images of Case 1 show raised wound edges and a callused periwound. A debridement of the wound edges and the periwound is of paramount importance as it allows keratinocytes from wound edges to cross the base of the wound and prevent recolonization of the debrided wound by periwound bacteria. The concept of “targeted debridement” of areas with CIBL proposed by the authors did not address senescent edges or other areas that required debridement regardless of bacterial loads. The second case is more concerning as it depicts a clinically uninfected breast wound colonized with Pseudomonas aeruginosa detected by MolecuLight and confirmed by a wound culture. Pseudomonas aeruginosa is the “great white” in the infectious disease (ID) world. In 2024, the World Health Organization identified it as “the critical pathogen” needing new antimicrobials for the survival of humanity. It is an established fact that antimicrobials are not effective in treating biofilm-related bacteria typically seen in chronic wounds. As a result, utilizing a device that does not differentiate between planktonic and biofilm-related bacteria and then using systemic antibiotics to treat biofilm-related colonization is inappropriate. In Case 2, it was stated that Pseudomonas was resistant to all oral antimicrobials, while, in fact, there is only one oral antimicrobial (from the quinolone class) available to treat Pseudomonal infections. The treatment duration of four weeks was based on abnormal MolecuLight images. Prolonged antimicrobial treatment is against ID’s basic principle to use antimicrobials for the shortest duration possible to avoid the creation of MDR and to prevent additional side effects of therapy. The authors’ experimental approach published in the Practice Reflections section of the journal is not only potentially harmful to patients but will make wound care practitioners liable for breaches of the well-accepted standards of care. The MolecuLight’s “claim to fame” that it can facilitate debridement and decrease antimicrobial usage fell short in this case series. In the first case, the wound was not properly debrided, and there were no images to determine if debridement was adequate in the second case. In both cases, antibiotics were used inappropriately. The article’s message is that if the wound is contaminated or sharp debridement is not sufficient, then the administration of antimicrobials for the treatment of wounds without any clinical signs of infection for the duration determined by the device is deeply disturbing. It is against the pillars of infectious diseases and contradicts Infectious Disease Society of America (IDSA) guidelines for treatment of soft tissue infections.5 In my practice, we do not use fluorescent imaging while successfully treating similar patients. We use aggressive debridement while remodeling wound base and edges and rarely prescribe antimicrobials. The usage of the razor blade to even out and merge the wound base and periwound and a dermascope with a 10-fold magnification to monitor the quality of our debridement improves wound outcomes. Developing a single antibiotic takes 10 to 15 years of research and development and costs $1.3 to $1.7 billion.6 At the same time, inappropriate administration of a single antimicrobial can lead to bacterial antimicrobial resistance (AMR) and make the entire antibiotic class ineffective within days. In fact, being a wound care patient adds a risk factor for MDR pathogens, and wound care clinics are known vectors for bacterial AMR, which claims 700,000 lives every year.7 If no urgent actions are taken, by 2050, AMR will cause an estimated loss of 10 million lives and $100 trillion.7 Incorporating experimental diagnostic and therapeutic models without a sound understanding of wound care and infectious disease concepts is bound to be detrimental to patients. It will put humanity’s future at risk. Additional wound debridement and remodeling training, along with learning ID basics, would improve wound outcomes, obliviating the need to look for invisible foes. We encourage collaboration with the IDSA to develop scientifically sound diagnostic and treatment modalities that will lead to the best patient outcomes. Igor Melnychuk, MD, CLT, BC in Infectious Disease and CMET-certified in Wound CareUniversity of North Carolina at Chapel HillEdward Via College of Osteopathic Medicine Carolinas, and Charles GeorgeVA Medical CenterAsheville, North Carolina