Bacterial Diseases

Abstract

Bacteria are extremely diverse and versatile environmental organisms and human pathogens. Bacterial infections may be acute and life-threatening or chronic and relapsing; community-acquired or nosocomial. They may elicit non-inflammatory, pyogenic, granulomatous, or lymphohistiocytic reactions. Some bacterial diseases are mediated by toxins, sometimes without multiplication of the pathogens within the body, and are more properly described as intoxications. The most common tissue response, however, is acute inflammation that is dominated by neutrophils; these bacteria are known as pyogenic or pus-forming. When necrosis of tissue ensues, an abscess may result, complicating the job of host defenses and of the physician who intercedes with therapeutic measures. Another group of bacteria, known as facultative intracellular pathogens, multiply within macrophages in the body and produce chronic infections with a granulomatous inflammatory response. A small, but important group ofbacterial pathogens produces a lymphocytic inflammatory response without granulomas.

Diagnosis and therapy of bacterial infections is accomplished optimally when clinicians, anatomic pathologists, and clinical microbiologists work in concert. Each has important tools to bring to bear on the clinical problem. Despite the importance of bacteria in human biology, they are often overlooked or incompletely studied by anatomic pathologists. The reasons for this neglect include the frequent presence of morphologically nonspecific acute inflammatory responses, difficulty of differentiating bacterial species morphologically, and the necessity of using a high-power, oil-immersion lens- the bête noire of the anatomic pathologist. A variety of special stains has been developed for study of bacterial infections. These stains have been used with great success to uncover “new” infections within the past 20 years. (The J Histotechnol 18:241, 1995)

Keywords:

• abscess
• bacteria
• granulomatous
• histologic stains
• host response
• pyrogenic