Experimental intravenous inoculation of Klebsiella rhinoscleromatis bacilli in albino rats: a histopathological and bacteriological study

Abstract

Scleroma, chronic specific granuloma of the nose and upper respiratory tract, is endemic in Egypt and many other countries. The exact pathogenesis of the disease as regards the aetiological role of Klebsiella rhinoscleromatis is contradictory. This work investigated the effect of experimental intravenous injection of K. rhinoscleromatis in albino rats to demonstrate that the micro-organism can fulfil Koch's postulates. Micro-organisms were isolated from biopsy specimens taken from nasal lesions of 10 patients in the granulomatous stage of scleroma. Specimens were subjected to bacteriological and histopathological examinations to confirm the diagnosis. A 100 microl volume of freshly prepared bacterial inoculum containing 10(8) cfu/ml was injected weekly in the tail vein of each of 30 albino rats for 5 consecutive weeks. Biopsy specimens were taken from sacrificed animals and subjected to bacteriological and histopathological examinations. Positive histopathological diagnosis of scleroma was reported in the nose of 66.7% of rats, the larynx of 46.7%, the lungs of 26.7% and liver of 20% of rats. Bacteriological techniques were successful in revealing K. rhinoscleromatis from the nose of 36.7% of rats, the larynx of 30% and the lungs of 20% of rats. Various techniques were carried out to demonstrate the micro-organisms in tissue sections. Two histochemical stains for bacteria were employed: silver and Periodic Acid Schiff (PAS) stains. Immunoperoxidase technique using Klebsiella capsular type 3 antiserum was applied. It gave positive results in 66.7% of the 6 stained liver sections in spite of negative bacteriological cultures. The histiocytic nature of the Mikulicz cells was confirmed using alpha-1 antitrypsin, an immunohistochemical marker of histiocytes, and by studying the ultrastructural features of Mikulicz cells using the transmission electron microscope.