Preliminary Results, Perspectives, and Proposal for a Screening Method of In Vitro Susceptibility of Prototheca Species to Antimicrotubular Agents

Development of Loop-Mediated Isothermal Amplification for the Detection of Prototheca bovis Directly from Milk Samples of Dairy Cattle

Prototheca bovis is an algal emerging pathogen in dairy farms causing refractory protothecal mastitis with increasing incidence worldwide and significant economic impact. P. bovis infects cows throughout the lactation cycle, including dry periods, and can persist in the udder and the environment for a long time. Since P. bovis does not respond to treatments with antibiotics, the suggested sanitary measure to restrict the spread is culling infected animals. A point-of-care test for early detection of the causative agent is critically needed to guide farm management and the appropriate treatment of mastitis. Loop-mediated isothermal amplification (LAMP) is a highly specific molecular method, time-saving, cost-effective and easy to perform in limited settings. This study aimed to develop a LAMP assay for P. bovis detection directly from milk samples; it was employed in conjunction with a commercial DNA extraction kit which was previously used to extract DNA from milk specimens containing microbes. The LAMP assay detected P. bovis DNA within 1 h in milk samples spiked with P. bovis at a concentration of 50 cells/μL, enabling on-farm disease monitoring and decision-making based on a reliable diagnosis. The LAMP method will contribute to the accurate and rapid identification of P. bovis in asymptomatic or recurrent mastitis cases and consequently aid the implementation of targeted control measures and the reduction of losses in milk production.

In Vitro Activity of Quaternary Ammonium in Prototheca Isolated from Clinical Bovine Mastitis Identified by Mass Spectrometry and PCR Sequencing of the cytb Gene Marker

The in vitro algaecide activity of quaternary ammonium (QA) against Prototheca isolated from bovine clinical mastitis was investigated, in which the clinical severity was scored, milk samples were subjected to microbiological culture, and algal species were identified by molecular typing. A total of 4275 milk clinical samples of different cows from ten large dairy farms were used. Forty-four (1%) samples of cows from three dairy farms yielded growth of Prototheca, of which 88.6% (39/44) were identified as Prototheca bovis and 11.3% (5/44) as Prototheca sp. by MALDI-TOF MS, whereas 100% of the isolates were identified as P. bovis using PCR sequencing of the cytb gene. Among cows for which clinical severity scoring was available, 78.8% (26/33) and 21.2% (7/33) had mild and moderate infections, respectively, whereas no animal showed severe clinical signs. The algaecide activity of QA in Prototheca was observed in low concentrations among all isolates, in 20.4% (9/44) at 35 ppm, 36.4% (16/44) at 17 ppm, and 43.2% (19/44) at an 8 ppm, in addition to activity on three reference Prototheca strains. Overall, the study highlights the predominance of P. bovis as the causative agent of algal mastitis in bovines. Prototheca induced abnormalities preponderantly in the milk and mammary gland tissue of cows, and to our knowledge, our study is the first to apply clinical severity scoring in protothecal mastitis. In addition, the study underlines the activity of QA in low concentrations against Prototheca, indicating its potential use as an antiseptic/disinfectant in milking facilities and dairy environments.

Human protothecosis: A case report in northeastern Brazil

We describe a case of extensive human cutaneous protothecosis in the northeastern of Brazil. The diagnosis was made through histopathological examination of skin samples and culturing on Sabouraud dextrose agar, with identification through mass spectrometry. Treatment with itraconazole failed and was switched to liposomal amphotericin followed by voriconazole with clinical cure. Prothotecosis should be a diagnostic hypothesis when there are skin lesions after trauma, specially in situations of atypical evolution.