BACKGROUND:
Necrotizing soft tissue infection (NSTI) is a life-threatening infection associated with high morbidity and mortality. Treatment consists of surgery and antibiotics. Many studies have addressed NSTI and its subtypes, but few have reviewed the clinical, radiological, and pathological differences between the polymicrobial and monomicrobial diseases. The objective of our study was to evaluate the clinical, radiological, and pathological features of patients with polymicrobial (NSTI I) and monomicrobial (NSTI II) infections and their association with outcome.

METHODS:
The cohort consisted of patients hospitalized with NSTI at a tertiary medical center in 2002-2019. The medical charts were reviewed for clinical, radiological, and pathological features. Findings were compared between patients in whom blood/tissue bacterial cultures yielded one or more than one pathological isolate. The primary clinical outcome measure of the study was all-cause mortality at 90 days. Secondary outcomes were duration of hospitalization, intensive care unit (ICU) admission, score on the LRINEC (Laboratory Risk Indicator for Necrotizing Fasciitis), and need for vasopressor treatment.

RESULTS:
A total of 81 patients met the inclusion criteria: 54 (66.6%) with monomicrobial NSTI and 27 (33.3%) with polymicrobial NSTI. There were no significant between-group differences in in-hospital and 90-day mortality. On multivariate analysis, the monomicrobial disease group had a significantly higher 90-day mortality rate in addition to higher rates of in-hospital mortality, ICU admission, and vasopressor use than the polymicrobial disease group.

CONCLUSION:
Our study is the first to compare the clinical, radiological, and pathological differences between the two most common types of NSTI. The results demonstrate better prognosis for polymicrobial NSTI, with minimal ICU stay, lower mortality, and lower use of vasopressors.

LEVEL OF EVIDENCE:
Prognostic and epidemiological, level III.





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