Efficacy of ronidazole for treatment of feline Tritrichomonas foetus infection

OBJECTIVES: To determine the efficacy of ronidazole (RDZ), tinidazole (TDZ), and metronidazole (MDZ) against Tritrichomonas foetus in vitro and of RDZ for treatment of feline naturally occurring or experimentally induced T. foetus infection. ANIMALS: A cat naturally infected with T. foetus infection and diarrhea. Ten specific-pathogen-free (SPF) kittens. PROCEDURE: RDZ, TDZ, and MDZ were tested for activity against 3 different feline isolates of T. foetus in vitro. RDZ then was administered to a naturally infected cat at 10 mg/kg PO q24h for 10 days. SPF kittens were infected orogastrically with feline T. foetus and treated with either placebo or RDZ (10 mg/kg PO q12h for 14 days). Cats with relapsing infection or those receiving placebo were treated subsequently with RDZ (either 30 or 50 mg/kg PO q12h for 14 days). Feces were examined for T. foetus by direct microscopy, culture, and polymerase chain reaction (PCR) testing weekly. RESULTS: Both RDZ and TDZ killed T. foetus at concentrations >0.1 microg/mL in vitro. In the naturally infected cat, RDZ abolished diarrhea and T. foetus infection for 85 days after treatment, at which time infection and diarrhea relapsed. Retreatment with RDZ eradicated diarrhea and T. foetus infection for over 407 days. In experimentally induced infection, RDZ at 10 mg/kg caused initial improvement, but infection relapsed in all 5 cats 2 to 20 weeks after treatment. At 30 or 50 mg/kg, 10/10 cats were negative for T. foetus infection for follow-up durations of 21 to 30 weeks after treatment. CONCLUSIONS AND CLINICAL RELEVANCE: Oral administration of RDZ at 30 to 50 mg/kg q12h for 14 days resolved diarrhea and eradicated infection (on the basis of polymerase chain reaction [PCR] testing) in 1 naturally infected cat and 10 experimentally inoculated cats receiving a different isolate of T. foetus.     

Fluorescence microscopy investigations of ligand propagation and accessibility under adherent cells

Fluorescence microscopy methods including total internal reflection fluorescence and confocal laser scanning microscopy have played a major role in modern cell biology research by permitting imaging of fluorescently tagged macromolecules in living cells. These methods are often used to examine the initial events in signal transduction, which involve interactions occurring between membrane receptors and ligands such as antibodies and growth factors. Most quantitative biophysical applications using these fluorescence imaging methods, including ligand binding assays, are based on the assumption that the fluorophore label of interest has equal access to all areas of the membrane on the cell. Our findings suggest that there is limited accessibility of fluorophores (25±2%)(-) under the basal membrane of adherent CHO-K1 cells expressing epidermal growth factor receptor plated on a bare glass in standard two-dimensional tissue cultures. The authors present a detailed study of the extent to which a small fluorescent dye molecule (Alexa 647) is able to propagate under the basal membrane of cells plated on a variety of biologically compatible substrates: fibronectin, bovine serum albumin, poly-d-lysine, collagen I, collagen IV, Geltrex?, and fibronectin such as binding polymer. For nonspecific dye propagation the best overall accessibility was achieved using a thin layer preparation of a commercially available basement membrane matrix, Geltrex? (67±8%). Coupling of a specific high affinity ligand (epidermal growth factor) to the dye did result in a moderate increase in propagation for most substrates examined. Despite the overall increase in propagation for most substrates (60%-80%), large areas under the central regions of the adherent cells still remained inaccessible to the fluorescently labeled ligand. More importantly, the presence of the specific ligand did not result in consistent increase in ligand propagation. Taken together these results suggest that the reduced accessibility is not exclusively due to steric effects, and the chemistry of both the ligand and the substrate may be important when working under conditions of reduced dimensionality.     

Response of white leghorn chickens of various B haplotypes to infection at hatch with subgroup J avian leukosis virus

White leghorn chickens from seven 15.B congenic lines (genetically similar except for genes linked to the major histocompatibility complex [MHC] B haplotype) and two Line 0.B semicongenic lines were infected at hatch with strain ADOL Hc-1 of subgroup J avian leukosis virus (ALV-J). At 5, 8, 16, and 36 wk of age, chickens were tested for viremia, serum-neutralizing antibody, and cloacal shedding. Chickens were also monitored for development of neoplasia. In the 15.B congenic lines (B*2, B*5, B*12, B*13, B*15, B*19, and B*21) there were no significant differences in the incidence of viremia between B haplotypes. In fact, infection at hatch in all of the 15.B congenic lines induced tolerance to ALV-J because 100% of these chickens were viremic and transient circulating serum-neutralizing antibody was detected in only a few chickens throughout the 36 wk experiment. However, at 16 wk of age more B*15 chickens had antibody and fewer B*15 chickens shed virus than did the 16-wk-old B*2, B*5, or B*13 chickens. Moreover, compared with B*15 chickens, a higher percentage of B*13 chickens consistently shed virus from 8 wk postinfection to termination at 36 wk postinfection. The B haplotype had a transient effect on viral clearance in Line 0.B semicongenics, as more B*13 than B*21 chickens remained viremic through 5 wk of age. Very few (0%-18%) of the Line 0.B semicongenic chickens shed virus. By 36 wk of age, all Line 0 B*13 and B*21 chickens produced serum-neutralizing antibodies and cleared the virus. These results show that following ALV-J infection at hatch the immune response is influenced transiently by the B haplotype and strongly by the line of chicken. Although this study was not designed to study the effect of endogenous virus on ALV-J infection, the data suggest that endogenous virus expression reduced immunity to ALV-J in Line 15I5, compared with Line 0, a line known to lack endogenous virus genes.     

Trends in the frequency of calcium oxalate uroliths in the upper urinary tract of cats

Medical records from cats diagnosed with uroliths at nine United States veterinary teaching hospitals from 1980 to 1999, and records of cats with uroliths submitted for analyses to the Minnesota Urolith Center from 1981 to 2000, were evaluated. A 10-fold increase in frequency of upper tract uroliths occurred in cats during the 20-year interval at the nine veterinary teaching hospitals. Calcium oxalate emerged as the predominant mineral type in upper tract uroliths, having increased more than 50-fold during the study period. These results emphasize the need for increased awareness of the occurrence of upper urinary tract uroliths in cats.     

Urinary tract manifestations of protothecosis in dogs

Records of 13 dogs with systemic infection with Prototheca sp. from 3 veterinary teaching hospitals were reviewed. Acute renal failure secondary to disseminated infection with Prototheca zopfii was diagnosed in 2 dogs. In 1 dog, acute renal failure developed during administration of immunosuppressive drugs for treatment of anterior uveitis. During diagnostic evaluation of this dog, Prototheca sp. organisms were noted in urine sediment and renal biopsy specimens. In the 2nd dog, acute renal failure was diagnosed after treatment for bacterial cystitis. After diagnosis of protothecosis, organisms were successfully isolated by aerobic urine culture. Both dogs with acute renal failure did not respond to conventional medical therapy. In total, Prototheca sp. was noted in urine sediment in 4 of 8 dogs and successfully cultured from urine in 5 of 7 dogs. Four of 5 dogs had organisms noted in the kidneys on histopathologic examination. In all dogs, the species identified was P zopfii. Sensitivity testing of 3 isolates revealed wide differences in in vitro drug resistance. Examination and culture of urine is recommended as a practical method for diagnosis of systemic infection with Prototheca sp.     

Muscle cramps in two standard poodles with hypoadrenocorticism

Two standard poodles were evaluated for painful, episodic muscle cramps affecting their thoracic and pelvic limbs. Both dogs had been diagnosed with hypoadrenocorticism and were being treated with fludrocortisone acetate and prednisone when evaluated for muscle cramps. However, the muscle cramping started approximately 1 month prior to the diagnosis of hypoadrenocorticism. Findings on general physical examination included lethargy and dehydration. Neurological examination was normal between episodes. Serum biochemical abnormalities included hyperalbuminemia, azotemia, hyponatremia, hypochloremia, and hyperkalemia. Altering treatment to desoxycorticosterone pivalate resolved the electrolyte abnormalities and the episodes of muscle cramping in both dogs. The authors conclude that hypoadrenocorticism can be associated with episodes of painful muscle cramping in standard poodles.     

Characterization of the urogenital microbiome in Miniature Schnauzers with and without calcium oxalate urolithiasis

BackgroundCalcium oxalate (CaOx) uroliths are common in dogs. Humans with CaOx urolithiasis exhibit alterations of the urinary and urogenital microbiomes that might mediate urolith formation. Detection of urogenital microbes associated with CaOx in dogs could inform disease pathophysiology.ObjectiveTo identify compositional differences in the urogenital microbiome of Miniature Schnauzers with and without CaOx uroliths.AnimalsNineteen midstream, voided urine samples from Miniature Schnauzers with (n = 9) and without (n = 10) a history of CaOx urolithiasis.MethodsAnalytical cross‐sectional study. Microbial DNA was extracted from previously frozen urine samples and sequenced for the bacterial 16S rRNA V3‐V4 hypervariable regions. Diversity and composition of microbial populations were compared between urolith formers and controls.ResultsAlpha and beta diversity measures were similar between groups. Five individual bacterial taxa differed in abundance (indicator values >0.5 and P < .05): Acinetobacter, 2 Geobacillus variants, and Hydrogenophaga were overrepresented in the urine of urolith formers, and Sphingopyxis was overrepresented in controls. Two distinct subtypes of urine microbial composition were observed based on beta diversity measures, independent of urolith status, and other clinical variables.Conclusions and Clinical ImportanceAlthough we did not detect a difference in the overall urogenital microbial composition between groups, observed differences in individual bacterial taxa might be clinically relevant. For example, Acinetobacter was overrepresented in urolith formers and is associated with CaOx urolithiasis in humans. Two unique clusters of the microbiome were identified, independent of urolith status, which may represent distinct urotypes present in Miniature Schnauzers.