A new exanthematous disease in newborn infants caused by exotoxins producing methicillin-resistant Staphylococcus aureus; pathology from viewpoints of local and systemic levels of exotoxin and cytokine

Abstract

Neonatal exanthematous diseases induced by toxic shock syndrome toxin-1 (TSST-1)-producing methicillin-resistant Staphyloccocus aureus (MRSA) is one of emerging infectious diseases in Japan. We experienced 36 patients with this disease in National Kagawa Children's Hospital and in 13 patients of them, investigated the role of both the toxin and cytokines in pathogenesis of it. The results are summarized as follows: 1. The TSST-1 level was high in the umbilical inflammatory exudate of cases induced by umbilical infection and in the gastric fluid of cases induced by respiratory infection. The blood TSST-1 level was below the detection limit in most of the exathematous++ cases examined, but it was detected in one of the nine cases induced by respiratory infection and a case secondary to severe MRSA infection (phlegmonous abscess in buttock). 2. Local cytokine levels were examined in the abscess pus obtained from a case of severe MRSA infection and in the gastric fluid from cases induced by respiratory infection. The local levels of TNF [alpha], IL-1 [beta], IL-6 and IL-8 were markedly high, but the local levels of IL-2 and IFN-[gamma] were similar to their blood levels. 3. The severity of hypercytokinemia (IL-1 [beta], IL-2, IL-6, IFN-[gamma]) was proportionate to the severity of exanthematous disease. Accompanied by increased levels of inhibitory factors sTNF-R, IL-1 ra, sIL-2R and IL-10, this hypercytokinemia normalized soon within four or five days. 4. As compared to cases induced by umbilical infection, cases induced by respiratory infection often had higher blood cytokine levels and some of them had cardiorespiratory disorders. Based on the results of this study, we consider that this disease is generally induced by toxemia with a small number of toxins without tissue destructive lesions by MRSA infection and that this is closely related to the course of the disease that shows a tendency to a spontaneous recovery.