Oropharyngeal or gastric colonization and nosocomial pneumonia in adult intensive care unit patients. A prospective study based on genomic DNA analysis.

Colonization of the digestive tract has been supposed to be the source of many hospital-acquired infections, especially nosocomial pneumonia. To assess the relationship between oropharyngeal and gastric colonization and subsequent occurrence of nosocomial pneumonia, we prospectively studied 86 ventilated, intensive care unit (ICU) patients. Oropharyngeal or gastric colonizations were detected and quantified on admission and twice weekly during ICU stay. When nosocomial pneumonia was suspected on clinical grounds (new chest X-ray infiltrate and purulent tracheal secretions), diagnosis was assessed on fiberoptic bronchoscopy with quantitative cultures of a protected specimen brush sampling and/or a plugged telescoping catheter sampling yielding > or = 10(3) cfu/ml of at least one microorganism. Bacterial strains responsible for colonization and infection (Acinetobacter baumannii, Pseudomonas aeruginosa, Enterobacteriaceae, and Staphylococcus aureus) were compared using pulsed-field electrophoresis. A total of 31 cases (36%) of pneumonia were diagnosed. Oropharyngeal colonization, detected either on admission or from subsequent samples, was a predominant factor of nosocomial pneumonia as compared with gastric colonization. For instance, oropharyngeal colonization with A. baumannii yielded a 7.45-fold estimated increased risk of pneumonia as compared with patients not yet or not identically colonized (p = 0.0004). DNA genomic analysis demonstrated that an identical strain was isolated from oropharyngeal or gastric samples and bronchial samples in all but three cases of pneumonia, due to S. aureus. These findings provide better knowledge of the pathophysiology of nosocomial pneumonia in mechanically ventilated patients.

Experimental intracranial aneurysms in rats. A gross and microscopic study.

Experimental cerebral aneurysms were induced in rats in which the left carotid artery was ligated. The rats were rendered hypertensive by the Goldblatt procedure, and fed a diet containing beta-aminopropionitrile. These intracranial aneurysms have significant gross and microscopic similarities to human berry aneurysms. The procedures and microscopic observations indicate that this experimental model could be useful for studying the development, pathophysiology, and therapy of saccular aneurysms.

Cytoplasmic tubular arrays in cells of American Burkitt's type lymphoma.

Aggregates of tubular arrays associated with cysternae of endoplasmic reticulum were observed in untreated primary American form Burkitt's lymphoma. The tumor occurred in a white female child who died with severe central nervous system (CNS) involvement. Although the significance of the tubular structures and the mechanism by which they are formed remains unknown, the predilection of these structures for lymphoid and reticuloendothelial cells and their frequent association with either viral or suspected viral conditions cannot be overlooked. However, it is possible that the tubular structures may reflect an increased production of antibody protein in response to a viral antigen.

Myxovirus-like particles in cells of American Burkitt's-type lymphoma.

Distinct tubular arrays associated with cisternae of endoplasmic reticulum were observed in neoplastic lymphoid cells in a primary American Burkitt's-type lymphoma. A late relapse of the disease was complicated by severe CNS involvement. The pathogenesis of CNS involvement and the significance of the tubular arrays are discussed.