Apparent drug resistance to the organophosphate dimethyl (2,2,2-trichloro-1-hydroxyethyl) phosphonate by monogenetic trematodes.

Gyrodactylus elegans on goldfish, (Carassius auratus) from a commercial farm were resistant to recommended dosages of dimethyl (2,2,2-trichloro-1-hydroxyethyl) phosphonate. Controlled experiments suggest that a dosage 100 times the commonly recommended minimal dosage (.25 mg/l) was required to remove trematodes. A hypothesis is proposed to account for the development of drug resistant trematodes based on the life cycle of the parasites and continual drug exposure.

Renal toxicity. Tobramycin and gentamicin.

The new aminoglycoside, tobramycin sulfate, has been shown to be effective against the same microorganisms for which gentamicin is currently employed. This study compares the effects of these two antibiotics on renal function and ultrastructure in guinea pigs. Significant differences in the blood urea nitrogen of treated and nontreated groups, as well as between the gentamicin- and tobramycin-treated groups were observed. Gentamicin produced greater, more rapid elevations of the blood urea nitrogen, although all elevations were reversible. The ultrastructural pathology produced by tobramycin was similar to that previously described for gentamicin.

Pathogenesis of pyelonephritis. Escherichia coli-induced renal ultrastructural changes.

Escherichia coli-induced renal ultrastructural changes were observed 4 hr after the intravenous injection of 2 times 10-minus 6 bacteria. The initial changes consisted of mitochondrial swelling followed by intracellular vacuolation, nuclear membrane dilation, and increased lysosomal phagocytic activity. Alterations in the appearance of proximal tubular lysosomes included a loss of osmiophilic staining properties. Many of the involved cells showed necrosis and can presumably act as a nidus for bacterial proliferation.