A cross-sectional validation study of using NERDS and STONEES to assess bacterial burden

All chronic wounds are colonized by micro-organisms. Although the presence of bacteria is not necessarily harmful, and may be beneficial in some instances, accurate evaluation of wound-related bacterial damage and infection is crucial. A cross-sectional validation study involving 112 patients was conducted to estimate the specificity and sensitivity of clinical assessment variables individually and in combination to determine the presence and quantity of bacteria in the wound. The average age of study participants was 66 years (range 33 to 95 years) and most had leg (44) and foot (68) ulcers of approximately 6 months' duration. Wounds were evaluated using a mnemonic developed to evaluate the presence or absence of clinical signs of critical colonization (NERDS) or infection (STONEES) and results compared to semi-quantitative swab cultures. Wounds with debris, increased exudate, and friable tissue were found to be five times more likely to have scant or light bacterial growth; whereas, wounds with elevated temperature were eight times more likely to have moderate or heavy bacterial growth. When combining any three clinical signs, the sensitivity was 73.3% for scant or light and 90% for moderate and heavy bacterial growth and the specificity was 80.5% and 69.4%, respectively. Considering the importance of this clinical diagnosis, studies to examine the predictive validity of these assessment variables and culture results are warranted.