In vitro infection of primary cultures of leukocytes from kidneys of rainbow troutOncorhynchus mykiss showed that Renibacterium salmoninarum, an obligate pathogen of salmonids, survived within the mononuclear phagocytes (MP). Transmission electron microscopy revealed that intracellular survival of the bacterium partially depended on its ability to move from the phagosome and into the cytoplasm. Formalin-killed R. salmoninai-un? also escaped into the cytoplasm, albeit at a slower rate and after sustaining greater cell wall damage, suggesting that the extracellular protein of the bacterium plays a role in intracellular survival. The durability of its cell wall enhanced survival within MP and significant bacterial losses occurred only after 96 h as the MP died and exposed the bacteria to antibiotics in the media. The bacteria appeared to maintain a slow rate of intracellular division, and dividing bacteria were seen in the micrographs through 240 h. Live R. salmoninarum were cytotoxic to MP; however, the MP persisted in culture and k~lled limited numbers of the bacterium. Adherence of the bacterium to the surfaces of lymphocytes and erythrocytes was also noted. An economical and time-saving method for observing and quantifying information obtained from transmission electron microscopy is described. The colony-forming units assay and cell viability counts provided additional information to support the data from electron microscopy.

Gnotobiotic pigs inoculated with an Escherichia coli 0157:H7 strain isolated from a human with hemorrhagic colitis developed anorexia, lethargy, and watery diarrhea. Bacteria diffusely colonized the cecum and colon surfaces and the crypt epithelium. At bacterial attachment sites, microvilli were effaced, and epithelial cells were irregularly shaped, rounded, or detached. Submucosa, lamina propria, and mesentery were markedly edematous and contained many inflammatory cells. * Corresponding author. 953 on July 11, 2020 by guest http://iai.asm.org/ Downloaded from 954 NOTES on July 11, 2020 by guest http://iai.asm.org/ Downloaded from

Enterococcus (Streptococcus) durans is a motile, Grampositive coccus found in the alimentary tract of animals and in water, soil, sewage, and vegetati~n.~.~ Enteric disease and diarrhea were first associated with E. durans when Grampositive cocci were seen adhered to enterocytes in the small intestine of diarrheic pigs' and foals.Io E. durans subsequently was shown to induce diarrhea in gnotobiotic pigs7Jo and conventionally reared foalsI0 challenged with strains of porcine or equine origin.Diarrhea of 8 hours duration occurred in eight of ten, 1 1 -day-old Plott hound pups from a private residence. The bitch had been vaccinated against distemper, hepatitis, and parvovirus and did not have clinical signs. Despite intensive fluid and antimicrobial therapy, three pups died, and one of these was presented dead for necropsy. At necropsy, the pup was in excellent flesh, moderately dehydrated, and had severe hyperemia of the small intestinal wall from the duodenum through the jejunum. Scant amounts of liquid brown feces were present in the large intestine.Kidney and jejunum were fixed in 10% neutral-buffered formalin, embedded in paraffin, sectioned, and examined after staining with hematoxylin and eosin and Gram's stains. Pieces (0.5 cmz) of formalin-fixed small intestine were immersed in 3% glutaraldehyde in 0.1 M sodium phosphate buffer at pH 7.2 and refrigerated at 4 C until processed for transmission and scanning electron microscopic examinations by procedures described previ~usly.~ Portions of small intestine were inoculated onto sheep blood, brilliant green, MacConkey and cholistin naladixic acid agars, and incubated aerobically at 37 C. Feces were processed and negatively stained using procedures described previously8 and examined using an electron microscope.Microscopically, villi in the jejunum were long, slender, and densely colonized by Gram-positive coccoid bacteria (Figs. 1, 2). Bacterial colonization of enterocytes extended from the tips to the base of villi. The morphologic structure of enterocytes in areas with bacterial adherence was unaltered, except for changes attributed to post-mortem decomposition. Intestinal crypts were orderly in arrangement and structure, although a few crypts were dilated and contained neutrophils. Blood vessels in the submucosa, tunica muscularis, and serosa were dilated and blood-filled. The lumens of venules in the lamina propria were sometimes occluded by fibrinous thrombi. A few neutrophils were admixed with coccoid and rod bacteria in the jejunal lumen; but in general, inflammation was mild.Ultrastructurally, coccoid bacteria were closely apposed to enterocytes (Fig. 3). Fine filaments consistent in morphologic structure with fimbriae extended from bacterial cell walls to adjacent bacteria and to enterocyte brush borders (Fig. 3). Swelling of cytoplasmic organelles and distortion of microvilli most likely resulted from post-mortem decomposition. Intracellular cocci were frequently seen within lysozomes of villous epithelial cells; but the morphologic integrity of intra...

Abstract. Serum-free mouse embryo (SFME) cells, derived in medium in which serum is replaced with growth factors and other supplements, are proastroblasts that are acutely dependent on epidermal growth factor (EGF) for survival. Ultrastructurally, an early change found in SFME cells deprived of EGF was a loss of polysomes which sedimentation analysis confirmed to be a shift from polysomes to monosomes. The ribosomal shift was not accompanied by decreased steady-state level of cytoplasmic actin mRNA examined as an indicator of cellular mRNA level. With time the cells became small and severely degenerate and exhibited nuclear morphology characteristic of apoptosis. Genomic DNA isolated from cultures undergoing EGF deprivation-dependent cell death exhibited a pattern of fragmentation resulting from endonuclease activation characteristic of cells undergoing apoptosis or programmed cell death. Flow cytometric analysis indicated that cultures in the absence of EGF contained almost exclusively Gl-phase cells. Some of the phenomena associated with EGF deprivation of SFME cells are similar to those observed upon NGF deprivation of nerve cells in culture, suggesting that these neuroectodermal-derived cell types share common mechanisms of proliferative control involving peptide growth factor-dependent survival.

Coxiella burnetii infection in domestic animals occurs in many parts of the world, including the Mediterranean region, 2,3 Great Britain, 8 Australia, 5 California, 4 Idaho, 12 and Ontario, Canada. 9 The organism is an obligate intracytoplasmic parasite in the family Rickettsiaceae. It causes Q fever in man and occasionally outbreaks of abortions in food animals such as sheep, goats, and dairy cows. The purpose of this report is to describe the pathology and microbiologic findings of a recent outbreak of abortion in sheep from northcentral California. Four aborted near-term lambs and 2 placentas were submitted for diagnostic examination to the Animal Disease