Pathology of infectious diseases: new agents, opportunistic, neglectable, emergent, reemergent diseases and why not super resistant nosocomial bacteria?

Duarte-Neto, Amaro Nunes

report Death from pan-resistant superbug, in this issue of Autopsy & Case Reports, describing the autopsy of a α-1-antitrypsin deficient patient who was a chronic corticosteroid user and developed fatal pneumonia caused by Acinetobacter baumannii resistant to all tested antibiotics. 11 The description of the pathology of multi-resistant pyogenic agents may raise relevant insights for understanding the pathogenesis of infection and the virulence of an agent. For example, Pseudomonas aeruginosa, is a gram-negative bacillus, which causes pyogenic infection, with a particular vascular tropism inducing coagulative vessel necrosis and ischemic tissue damage. 12 In the case described by Nichols, I am struck by the predominantly macrophage inflammatory response with a large number of bacteria phagocytized by alveolar macrophages (Figure 2 of the article). Some hypotheses may arise for this morphological scenario, which may be answered in the future by controlled experimental studies: is the macrophage response effective in destroying A. baumannii? Are the macrophages present type M1 or M2? Are the neutrophil response, complement, and antibodies compromised? It should be considered that the patient was a chronic user of corticosteroids. However, are there particularities in A. baumannii virulence? Some of these pathogenetic responses, if answered, may allow the discovery of new therapies. Therefore, the relevance of a detailed description of the pathology of multi-resistant superbugs. As a note, some autopsies of A. baumannii pneumonia recently performed by Departamento de Patologia -Faculdade de Medicina da Universidade de São Paulo (personal observation, unpublished data), present the same morphological findings as described by Nichols. Of course, detailed pathology studies with larger numbers of resistant bacteria with different phenotypic susceptibility patterns would provide more information on pathogenesis. Perhaps it would only be possible through the interaction between different health centers around the world.