The present review describes a part of the author’s own experience in applying immunoperoxidase staining to routine histopathological diagnosis. The target disorder was focused on infection. In the practice of pathology diagnosis services, it is important for us diagnostic pathologists to judge whether the lesion is caused by an infection or not. When an infectious disease is highly likely, the visualization of pathogens within the inflammatory lesion is required to suggest a causative agent. Two main approaches the author would like to introduce include (1) the use of commercially available antisera showing wide cross-reactivity to a variety of bacteria and (2) the use of diluted patients’ sera. These immunohistochemical studies employing “low-specificity” and “high-sensitivity” probes are useful for confirming the localization of pathogen within the infectious lesion.
Part of the book: Immunohistochemistry
Pathological features of gangrene are described. Gangrene is commonly caused by infection of anaerobic bacteria. Dry gangrene belongs to noninfectious gangrene. The hypoxic/ischemic condition accelerates the growth of anaerobic bacteria and extensive necrosis of the involved tissue. Clostridial and non-clostridial gangrene provokes gas formation in the necrotic tissue. Acute gangrenous inflammation happens in a variety of tissues and organs, including the vermiform appendix, gallbladder, bile duct, lung, and eyeball. Emphysematous (gas-forming) infection such as emphysematous pyelonephritis may be provoked by Escherichia coli and Klebsiella pneumoniae. Rapidly progressive gangrene of the extremities (so-called “flesh-eating bacteria” infection) is seen in fulminant streptococcal, Vibrio vulnificus, and Aeromonas hydrophila infections. Fournier gangrene is an aggressive and life-threatening gangrenous disease seen in the scrotum and rectum. Necrotizing fasciitis is a subacute form of gangrene of the extremities. Of note is the fact that clostridial and streptococcal infections in the internal organs may result in a lethal hypercytokinemic state without association of gangrene of the arms and legs. Uncontrolled diabetes mellitus may play an important role for vulnerability of the infectious diseases. Pseudomonas-induced malignant otitis externa and craniofacial mucormycosis are special forms of the lethal gangrenous disorder.
Part of the book: Pathogenic Bacteria
Cytological diagnosis of infectious diseases is as important as the cytodiagnosis of malignancies, because the detection of pathogens in cytological specimens is crucially valuable for prompt and appropriate patients’ treatment. When compared with histological diagnosis, cytology is strong at detecting microbes under Papanicolaou and Giemsa stains. Host response against the infectious agent can be estimated by the type of background inflammatory cells. Patterns of the inflammatory cellular responses against extracellular and intracellular pathogens should be recognized. Immunocytochemical and molecular approaches can be applied, even when we have only one cytology specimen in hand. The cell transfer technique is useful to create plural material from one glass slide for immunocytochemistry and other techniques. In case of transmissible disorders including sexually transmitted diseases, the prompt and appropriate diagnosis will avoid avoidable transmission of infectious agents among people, and eventually contribute to the safety of the human society.
Part of the book: Innate Immunity in Health and Disease
Streptococcus pyogenes and Streptococcus pneumoniae, representative Gram-positive cocci, may cause both localized (skin and soft tissue) and systemic infections. Lobar pneumonia is a unique form of acute and severe lung infection of S. pneumoniae. Streptococcus viridans group, normal flora of the oral cavity, may lead not only to mucosal infection but also to aspiration pneumonia, infective endocarditis, and systemic infections. The severest and often lethal form of progressive and systemic infection includes fulminant streptococcal and pneumococcal infections. Autopsy is essentially important for the analysis of fulminant infections. Pathological features of varied streptococcal infections are illustrated and discussed. Immunohistochemical identification of the pathogen in formalin-fixed, paraffin-embedded sections is effective and valuable in confirming the type of infected pathogens.
Part of the book: Antibiotic Resistance - New Insights