Rapid enzyme analysis as a diagnostic tool for wound infection: Comparison between clinical judgment, microbiological analysis, and enzyme analysis

Abstract

In clinical practice, diagnosis of wound infection is based on the classical clinical signs of infection. When infection is suspected, wounds are often swabbed for microbiological culturing. These methods are not accurate (clinical judgment in chronic wounds) or provide results after several days (wound swab). Therefore, there is an urgent need for an easy-to-use diagnostic tool for fast detection of wound infection, especially in chronic wounds. This study determined the diagnostic properties of the enzymes myeloperoxidase, human neutrophil elastase (HNE), lysozyme and cathepsin-G in detecting wound infection when compared to wound swabs. Both chronic and acute wounds of 81 patients were assessed through clinical judgment, enzyme analysis and wound swab. Three promising enzyme models for detecting wound infection were identified. A positive test was defined as: at least one enzyme positive after 30 minutes (model 1), lysozyme and HNE positive after 30 minutes (model 2), myeloperoxidase positive after 5 minutes, and HNE or lysozyme positive after 30 minutes (model 3). All models were significant (p≤0.001). There was no correlation between clinical judgment and wound swab, indicating the need for novel diagnostic systems. Enzyme analysis is fast, easy to use and superior to clinical judgment when compared to wound swabs.

The diagnosis of infection in chronic leg ulcers: A narrative review on clinical practice

“…This popular threshold of 10 5 CFU has been used as a critical criterion for diagnosis of infection in chronic wounds, reasoning on the induction of local tissue damage in the wound because of the increase in the levels of bacterial‐related toxins and inflammatory mediators . Historically, the bacterial load at ≥10 5 CFU per one gram of tissue that was obtained from wound swabbing, biopsy, or ≥ 10 5 CFU/mL wound fluid can be seen as an indicator for wound infection . However, this bacterial load has been shown not to be accurate in diagnosing infection as there may be some bacteria with high virulence levels, especially when they have microbial synergy.…”

“…In fact, the prospective study by Cooper et al compared the bacterial load using three different techniques to obtain samples (swab, fluid, and biopsy), and found that the bacterial load depended on the wound size and the duration of the wound; as the highest bacterial load was found in the largest and the longest ulcers . In a prognostic study with a primary aim of evaluating the diagnostic properties of three enzymes identified from wound fluid of 81 patients with acute or chronic wounds (11 CLUs), Blokhuis‐Arkes et al examined the relationship between clinical and microbiological diagnosis of infection and found no relationship between the clinical judgement and microbiological results.…”

“…14 Historically, the bacterial load at ≥10 5 CFU per one gram of tissue that was obtained from wound swabbing, biopsy, or ≥ 10 5 CFU/mL wound fluid can be seen as an indicator for wound infection. 85 However, this bacterial load has been shown not to be accurate in diagnosing infection as there may be some bacteria with high virulence levels, especially when they have microbial synergy. In this case, the bacterial load may be lower than ≥10 5 CFU/g or ≥ 10 5 CFU/mL; however their pathogenic effects can be greater than each bacterium working independently.…”

Bacteriology of Naja atra Snakebite Wound and Its Implications for Antibiotic Therapy

“…More objective measurements such as laboratory and/ or validated physical criteria for snakebite wound infections should be established in the future. 36 The judicious use of antibiotics based on local bacterial patterns should be considered to improve the management of N. atra bite wound infections. Chen and others inspected 21 snakebite cases with wound infections and isolated at least 17 bacterial species from these wounds, including 17 caused by N. atra, one by T. stejnegeri, one by P. mucrosquamatus, and two by unknown snake species.…”

Diabetic foot infection: A critical complication

“…Early infection diagnosis and management are important for diabetics, yet diagnosis may be delayed because local signs and symptoms of infection are often diminished in a DFI because of concomitant peripheral neuropathy and PAD . However, a close correlation between neutrophil‐derived enzymes and wound infection status was reported in a clinical study involving 81 patients, of which 42% were diabetic …”