IMMUNOPEROXIDASE AND IMMUNOFLUORESCENT STAINING OF RICKETTSIA-RICKETTSII IN SKIN BIOPSIES - A COMPARATIVE-STUDY

Objective.--To compare immunofluorescent and immunoperoxidase staining of Rickettsia rickettsii in skin biopsies of patients suspected of ha ving Rocky Mountain spotted fever (RMSF). Design.--Immunofluorescent s taining results for R rickettsii from skin biopsies of patients suspec ted of having RMSF were obtained by computer and chart review. Immunop eroxidase staining for R rickettsii was performed on formalin-fixed, p araffin-embedded skin biopsies from the same patient population. Patie nts.--Twenty-six patients who were clinically suspected of having RMSF were included in this study. Skin biopsies of these patients were exa mined for evidence of RMSF by immunofluorescence and routine histology . Main Outcome Measures.--The sensitivity and specificity of both immu nofluorescent and immunoperoxidase staining techniques were calculated . The chi(2) method was used to assess significance. Results.--Both te sts were highly significant for the detection of R rickettsii (P < .01 ). The sensitivity and specificity of the immunofluorescent and immuno peroxidase staining techniques for the identification of RMSF were ide ntical. No significant difference between these tests was identified ( P > .05). Conclusion.--The sensitivity and specificity of immunofluore scent and immunoperoxidase staining of R rickettsii in routinely proce ssed, paraffin-embedded skin biopsies of patients suspected of having RMSF are identical. Although not as rapid as the immunofluorescent tec hnique, immunoperoxidase staining of R rickettsii has advantages over the immunofluorescent technique; these include easier antigen localiza tion and concomitant viewing of the corresponding histopathology.