Staphylococcus aureus isolates from five large teaching hospitals and one medium-size community hospital located in geographically distant parts of Brazil, in the south and southeast (Rio de Janeiro, Niteroi, Sao Paulo, Porto Alegre) and in the north (Manaus), were tested for their antibiotic resistance patterns and genetic backgrounds. Eighty-five of the 152 isolates were identified as methicillin-resistant S. aureus (MRSA) by using a combination of an agar dilution screen and a mecA gene-specific DNA probe. All MRSA isolates were resistant to penicillin, erythromycin, gentamicin, oxacillin, and cephalothin, and the majority of isolates (74%) were also resistant to chloramphenicol, sulfamethoxazole-trimethoprim, ciprofloxacin, and clindamycin as well and were susceptible only to vancomycin. Isolates obtained from hospitals in Sao Paulo, Rio de Janeiro, Niteroi, and Porto Alegre (1,600 km from one another) and Manaus (3,700 km from Rio de Janeiro) were examined by a variety of molecular fingerprinting techniques: the nature of the mecA polymorph and Tn554 attachment sites and restriction fragment length polymorphism of genomic DNAs after SmaI restriction and separation of the digested DNA by pulsed-field gel electrophoresis. The overwhelming majority of the isolates shared a common pulsed-field gel electrophoresis pattern and carried mecA polymorph III in combination with Tn554 pattern B, indicating the presence of a single, epidemic MRSA clone spread over large geographic distances of Brazil.

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Electron microscopy of bacterized and axenic trophozoites of Entamoeba histolytica showed only slight differences in ultrastructure between the two . As with other species of Entamoeba so far studied, this species lacks typical mitochondrial structures and formed endoplasmic reticulum . Dense clusters of glycogen particles are especially characteristic in axenic amebas . Microtubular structures 360 A in diameter appear randomly oriented in both bacterized and axenic trophozoites . Ribonucleoprotein (RNP) bodies are of two typical formselongate, parallel arrays of helices (the classical chromatoid bodies), and short helical fragments . Both kinds of helix show a recurring pitch angle of 68-80°and an over-all diameter of 480 A . RNP particles comprising the helices average 180 A in diameter . The longitudinal axes of adjacent helices are 440 A apart . Following RNase digestion of water-soluble methacrylate sections, helices show a core approximately 60 A in diameter. Short helices are also associated with digestive vacuoles . Free RNP particles per se are never seen within digestive vacuoles, but intact short helices are frequently detected closely associated with the external membrane of digestive vacuoles . In some cases, continuation of externally intact helical forms could be related to filamentous material within the vacuole . Acid phosphomonoesterase activity could be demonstrated within digestive vacuoles where deposition of reaction product is especially intense on the filamentous material .

It has been established that, in those species studied, intraluminar digestion does not occur in triclad flatworms (Willier, Hyman and Rifenburgh, 1925;Jennings, 1957), but that digestion takes place within food vacuoles in the phagocytic cells of the gastrodermis. A number of investigators have observed the disintegration of ingested food particles within these cells (Arnold, 1909;Saint-Hilaire, 1910;Jacek, 1917;von Levitzow, 1943), but the methods they employed did not permit elucidation of the mechanisms involved except in a most general way. Kelley (1931), studying the intracelular digestion of nucleoprotein in D. dorotocephala by means of the Feulgen reaction with and without acid hydrolysis, showed that the ingested material was hydrolyzed within the first two hours.To our knowledge, no previous study has characterized the hydrolytic enzymes in the phagocytes of planarians. The present report considers the relationship of three such enzymes to current concepts of intracellular digestion. Materials and MethodsSpecimens of Dugesia dorotocephala and D. tigrina were used for this study. The animals were maintained as stock cultures at 18° C. and fed routinely once every ten days on minced rat or mouse liver. Experimental animals were isolated in fingerbowls and starved for at least three weeks. Some of these were fed raw rat or mouse liver, and others boiled liver to determine if enzyme activities in raw food were transferred to the gut. No differences in enzyme activities between animals fed raw or boiled liver were demonstrable by the staining methods employed. The worms were observed during feeding ; post-feeding times were determined from the moment the animals ceased feeding.For the demonstration of those enzyme activities surviving chemical fixation, specimens were initially fixed in warm (37° C.) Baker's calcium-formalin for 5 minutes to prevent discharge of the gut contents. They were then placed in calcium-formalin at 4° C. for 24 hours, washed for 5 minutes in distilled water and cut on a CCX-freezing microtome at 8-10/*. Material thus prepared was incubated for acid phosphatase activity by a slight modification of the method of Gomori (1952). Sections were incubated for 15-30 minutes in a 0.1 M 2glycerophosphate and lead nitrate mixture buffered to pH 5.0 with 0.05 M acetate buffer.Aminopeptidase activity was visualized by the method of Burstone and Folk (1956). Animals were placed on Monel grids and frozen in isopentane chilled by liquid nitrogen to -160° C. After quenching, the worms were dehydrated for 24 118, 315-323.

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