In vitro algicidal effect of guanidine on Prototheca zopfii genotype 2 strains isolated from clinical and subclinical bovine mastitis

Prototheca species have increasingly been reported to be opportunistic pathogens that cause mastitis in dairy herds, and it poses an emergent problem because at present, there are no effective therapies for the treatment of protothecal mastitis. This study investigated the in vitro algicidal effect of guanidine on 75 Prototheca zopfii genotype 2 strains isolated from 75 cases of clinical and subclinical bovine mastitis. All strains were susceptible to guanidine in vitro with minimal algaecide concentrations ranging from 0·001 to 0·035%. Guanidine is known to have a high microbicidal effect and is considered to be a new generation microbicidal compound. It is not toxic to human mucous membranes and conjunctivas at low concentrations and has been used as a disinfectant in swimming pools and as an antiseptic for human wounds. The algicidal action of guanidine at low concentrations indicates that it could be an alternative disinfectant or antiseptic for cleaning of the dairy environment and milking equipment, in pre- and postdipping solutions, in the chemical dry therapy of bovine teats and even in the intramammary therapy of P. zopfii infections. This is the first report of the in vitro algicidal effect of guanidine on P. zopfii strains of animal origin.

SIGNIFICANCE AND IMPACT OF THE STUDY

Prototheca zopfii genotype 2 is an opportunistic pathogen of bovine mastitis. To date, no effective therapies against protothecal mastitis have been developed. The in vitro algicidal effect of guanidine on 75 P. zopfii genotype 2 strains isolated from cows revealed that all of the isolates were susceptible to the compound at low concentrations, which indicates that guanidine may be used as an antiseptic/disinfectant for dairy milking equipment, in pre- and postdipping solutions, and as a chemical dry therapy or an intramammary therapy. This study describes the in vitro algicidal effect of guanidine on P. zopfii for the first time.

Fluorescence spectroscopy in renal ischemia and reperfusion: noninvasive evaluation of organ viability

BACKGROUND

Damage provoked by ischemia in renal transplants is difficult to quantify. To determine whether a donated organ is fit for transplantation. We sought to correlate the findings of fluorescence spectroscopy (FS) with histologic evidence of ischemic injury and organ viability.

METHODS

Kidneys of 33 rats were submitted to FS of the upper and lower poles as well as the middle third. Excitation was generated by the laser's wavelengths of 408, 442, and 532 nm. Rats were randomized into groups with the 30, 60, and 120 minutes warm ischemia before analysis by FS, that was repeated at 5 minutes after reperfusion.

RESULTS

FS results in the reperfusion phase correlated with ischemia time and degree of histologic injury. After 60 or 120 minutes of ischemia, the excitation lasers of 532 and 442 nm resented a significant negative correlation coefficient with the histological grade (r = -0.61 and r = -0.73, respectively).

CONCLUSIONS

There was a strong correlation between FS and histologic changes only in the reperfusion phase after renal ischemia. The method was thus unable to assess the viability of organs before transplantation.

Evaluation by fluorescence spectroscopy of the most appropriate renal region for obtaining biopsies: a study in the rat

INTRODUCTION

Renal puncture biopsies are directed at the lower poles of the organ to decrease the risk of hemorrhage and complications.

OBJECTIVES

To evaluate by fluorescence spectroscopy (FS) the most appropriate renal region (in terms of metabolic changes) to obtain a biopsy.

MATERIALS AND METHODS

The kidneys of 33 Rattus norvegicus rats were submitted to FS detection in the upper and lower poles and in the middle third. Excitations were generated with lasers at wavelengths of 408, 442, and 532 nm. Animals were divided at random into groups of warm ischemia (30, 60, and 120 minutes), whose kidneys were again analyzed by FS, as well as after 5 minutes of reperfusion using the same excitation beams in the same renal regions. Then the kidneys underwent histologic preparation and examination.

RESULTS

The middle third area of the rat's kidneys proved to be significantly more sensitive to ischemic and reperfusion changes than the renal poles, as determined by FS (P < .001).

CONCLUSIONS

The middle third of the kidney was the most appropriate site for a renal biopsy to monitor a transplanted organ.