Swabs and other sampling techniques

Human as the Ultimate Wound Healing Model: Strategies for Studies Investigating the Dermal Lipidome

PURPOSE OF REVIEW

Educate the reader of the multiple roles undertaken by the human epidermal lipidome and the experimental techniques of measuring them.

RECENT FINDINGS

Damage to skin elicits a wound healing process that is capped by the recreation of the lipid barrier. In addition to barrier function, lipids also undertake an active signaling role during wound healing. Achievement of these multiple functions necessitates a significant complexity and diversity in the lipidome resulting in a composition that is unique to the human skin. As such, any attempts to delineate the function of the lipidome during the wound healing process in humans need to be addressed via studies undertaken in humans.

SUMMARY

The human cutaneous lipidome is unique and play a functionally significant role in maintaining barrier and regulating wound healing. Modern mass spectrometry and Raman spectroscopy based methods enable the investigation epidermal lipidome with respect to those functions.

Sample procurement for cultures of infected wounds: a systematic review

OBJECTIVE

Identifying the responsible pathogen is required in order to select optimum antimicrobial therapy for infected wounds, but the best techniques to use remain the subject of debate. Our aim was to assess the evidence on the value of wound swabs compared with biopsies.

METHOD

We conducted a systematic literature review with the terms 'wound infection', 'wound swab', 'wound swab technique', 'wound biopsy', 'wound culture', 'wound swab comparison', 'Levine swab technique', 'microbiological technique', 'specimen handling', 'bacterial load', 'perioperative care', 'swab', and 'culture'. We examined yields in identifying relevant pathogens, summarised salient features of qualifying studies, and defined knowledge gaps and endpoints that future studies should address.

RESULTS

Studies have been inconsistent, lacking specificity regarding wound types, clinical features, and sampling methods. We found moderate quality evidence that punch biopsies provide qualitative and quantitative information about the bacterial load and tissue reaction with nearly 100% sensitivity, 90% specificity and 95% accuracy for predicting wound closure. Biopsies are relatively invasive, costly, require skilled operators, and potentially exacerbate infection. Needle aspiration samples a limited portion and may enter uninfected tissue and extend infection. Wound swabs are minimally invasive, easier to perform and widely employed in clinical practice, but techniques vary. In comparative studies, the Levine technique was superior to the Z-swab techniques, and biopsies were more sensitive for antibiotic-resistant wounds than Levine or Levine-like swabs, suggesting that swabs may be useful for initial wound monitoring, but biopsies are preferred when antibiotic resistance is suspected.

CONCLUSION

The Levine swab is superior to the Z-swab technique and may be useful for initial wound monitoring, but quantitative biopsies are preferred for evaluation of antibiotic-resistant wounds and to monitor the response to treatment. There is limited evidence on the role of wound swabs for detecting wound colonisation versus infection and the impact of culture-guided therapy on such clinical outcomes as eradication of infection and accelerated healing. Future studies should specify patient populations, wound types, sampling protocols, and outcomes based on culture yield and treatment results, using rigorous statistical methodology.

Laboratory diagnosis of bone, joint, soft-tissue, and skin infections

The diagnosis of infections of bones, joints, skin, and soft-tissues requires the combined use of a number of laboratory and pathology tests. The diagnosis of most infections requires microbiological cultures, both for isolation and for identification of causative organisms, as well as for antimicrobial susceptibility testing. Chemical analysis of joint fluids and histopathologic examination of infected tissues are often necessary to distinguish infections from other causes of inflammation, as well as to provide information as to the type of infection before the results of cultures are available. At this time, the use of molecular amplification tests is of limited value in the diagnosis of these infections, their value primarily being as adjunct tests for the diagnosis of rare or unusual infections.

Topical negative pressure using a drainage pouch without foam dressing for the treatment of undermined pressure ulcers

Topical negative pressure is gaining popularity as an acute and chronic wound management technique. In general, foam dressing is applied to the wound surface to maintain negative pressure. Due to the potential for clogging by the foam dressing, topical negative pressure cannot be used when there is a high volume of necrotic tissue or massive infection present. In this study, topical negative pressure was applied using a drainage pouch without any dressing. Topical negative pressure was applied to 8 patients with 9 pressure ulcers complicated by undermining. This approach was effective in the treatment of all 9 ulcers and allowed the wounds to be visualized while maintaining negative pressure. Since this technique can be performed without foam dressing, it can be used to treat early-stage infectious pressure ulcers in which there is a lot of necrotic tissue.

CONCLUSION

Topical negative pressure without dressing is an extremely effective treatment of pressure ulcers complicated by undermining.

Infection control: validity and reliability in wound swabbing

Wound infection is initially identified by the recognition of clinical signs and symptoms such as pus and cellulitis. Wounds are, however, cultured in order to establish the causative organism and ensure appropriate treatment. A 'gold standard' method for wound sampling has not been established although the literature details wound swabbing and looks at the variations in practice within this method. A number of procedural issues are raised which prompt the need for further study to eliminate these variables and reach consensus as to how to achieve a meaningful result, thereby increasing the validity and reliability.

Swab taking

Experienced clinicians offer top tips to guide practice on specific wound-care issues.