Fig. 1

Diagnostic performances of abdominoperineal location and immunodeficiency for predicting absence of group A streptococcal documentation. The three top pie charts represent the proportions of group A streptococcal documentation, abdominoperineal infections and immunodeficiency in the whole 224-patient population of surgically confirmed necrotizing soft tissue infections. The two bottom pie charts represent the proportion of group A streptococcal documentation in the subgroup of patients with abdominoperineal infections (bottom left chart) or in immunocompromised patients (bottom right chart). Diagnostic performances of an abdominoperineal location of infection and of immunodeficiency for predicting the absence of group A streptococcal documentation were calculated using a contingency table approach. Immunodeficiency encompassed active cancer, chemotherapy within the last 3 months, previous HIV infection whatever the AIDS status, the CD4 lymphocytes counts or the viral load, any immunosuppressive drugs including chronic systemic steroid treatment (whatever the dose but for at least 3 months). PPV, positive predictive value; NPP, negative predictive value; Se, sensitivity; Sp, specificity