Skin Cultures May Aid in Prediction of Bloodstream Infection Pathogens

Staphylococcus aureus and Pseudomonas aeruginosa skin cultures may help predict the pathogens involved in bloodstream infections in patients with epidermal necrolysis, according to study results published in the Journal of the American Academy of Dermatology.

Epidermal necrolysis involving ≥10% body surface area is a life-threatening condition that is often complicated by bacterial infections. The most frequent and most life-threatening bacterial infections are bloodstream infections. Although the relationship between bloodstream infections and skin bacterial colonization has been described in burns, data from epidermal necrolysis is lacking. Therefore, this retrospective observational study investigated the epidemiology of bloodstream infections in epidermal necrolysis involving a body surface area ≥10% and the diagnostic performance of skin cultures for predicting the pathogens isolated from bloodstream infections.

A total of 98 patients who were referred in the acute phase of epidermal necrolysis involving a body surface area ≥10% between 2009 and 2017 were included in the study. All relevant bacteriologic and clinical data were collected, which included blood and skin culture results, number, severity, and time of bloodstream infection. Specificity, sensitivity, predictive values of skin cultures, and the effect of the bacterial inoculum were investigated.

Of the 98 patients, 46 (46.9%) had 1 or more bloodstream infection episodes during their hospital stay: 17 (36.9%) were infected with S aureus and 17 (36.9%) were infected with P aeruginosa. In 32 cases (71.1%), skin cultures were consistent with blood cultures. The positive and negative predictive values for S aureus were 57.7% and 89.4%, respectively; the positive and negative predictive values for P aeruginosa were 50.0% and 80.9%, respectively. Further, the sensitivity and specificity for S aureus was 88.2% and 60.7%, respectively, and for P aeruginosa was 75.0% and 56.4%, respectively. Patients who had 1 or more skin culture growing S aureus had an odds ratio (OR) of having a bloodstream infection episode involving the same pathogen of 17.0 (P =.002), while patients who had 1 or more skin culture growing P aeruginosa had an OR of having a bloodstream infection episode involving the same pathogen of 8.0 (P =.005). According to post hoc analyses, bloodstream infection increased with cutaneous inoculum of S aureus but not with P aeruginosa.

Study limitations included a low number of bloodstream infections and the monocentric design.

Overall, the study authors concluded that, “Our results also highlight the importance of monitoring the skin colonization by repeated skin cultures to target the bacteria most probably involved in [bloodstream infection] and adapt antibiotics accordingly, even before the positivity of blood cultures.”

Reference

Lecadet A, Woerther PL, Hua C, et al. Incidence of bloodstream infections and predictive value of qualitative and quantitative skin cultures of patients with overlap syndrome or toxic epidermal necrolysis: a retrospective observational cohort study of 98 cases [published online March 16, 2019]. J Am Acad Dermatol. doi:10.1016/j.jaad.2019.03.030

This article originally appeared on Infectious Disease Advisor