The mode of transmission of Helicobacter pylori is unknown. Since viable bacteria have been shown to be excreted in feces from infected individuals and houseflies habitually develop and feed on excrement, we hypothesized that flies ingest and harbor H. pylori and, in turn, contaminate the human environment. This study examined the possible vector potential of houseflies (Musca domestica) for H. pylori. Caged houseflies were exposed to freshly grown H. pylori on agar plates. After a 6-h feeding period, the plates were removed and were replaced with sterile petri dishes containing a droplet of sterile brucella broth. At regular intervals, small numbers of houseflies were removed for microbiological and histological analysis, and the petri dishes were replaced with fresh sterile plates with fresh drops of brucella broth. The flies' bodies, the flies' dissected alimentary tracts, and excreta on the petri dishes were cultured for H. pylori, whose identity was confirmed by the urease, catalase, and oxidase reactions and Gram staining. In contrast to control flies, viable H. pylori could be isolated from external surfaces for up to 12 h and from gut and excreta for as long as 30 h after the initial feeding period. After 30 h other gram-negative bacteria overgrew the cultures of samples from all locations tested, rendering the selective culture of H. pylori colonies impossible. Histological analysis revealed Helicobacter-like organisms in the gut lumen and attached to intestinal epithelial cells. We conclude that houseflies can harbor viable H. pylori on their bodies and in their intestinal tracts. They are also able to disseminate viable H. pylori in excreta, and they may therefore present a significant reservoir and be a vector in the transmission of H. pylori.
Mammograms and histologic slides of a group of 320 women who had breast symptoms and a biopsy without cancer being found were reviewed. The mammographic features assessed were the parenchymal pattern and extent of nodular and homogeneous densities. In addition to the pathologic diagnosis, the histologic features assessed included epithelial hyperplasia and atypia, intralobular fibrosis, and extralobular fibrosis. Among premenopausal women, those with marked intralobular fibrosis were more likely to have large (3+ mm) nodular densities on the mammogram. Among postmenopausal women, epithelial hyperplasia or atypia was related to having nodular densities in at least 40% of the breast volume. In both groups, marked extralobular fibrosis was related to the presence of homogeneous density on the mammogram. We conclude that mammographic nodular densities may be an expression of lobular characteristics, whereas homogeneous density may reflect extralobular connective tissue changes.
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