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In vitro susceptibility of Prototheca zopfii genotypes 1 and 2
Hideto Sobukawa1, Rui Kano, Takaaki Ito
1Department of Pathobiology, Nihon University School of Veterinary Medicine, Kanagawa, Japan.
Abstract:
Prototheca zopfii causes bovine mastitis that leads to reduced milk production. Since P. zopfii isolates from mastitis have been assigned P. zopfii genotype 2, it suggests that this genotype is the etiologic agent of the infection. However, isolates of P. zopfii have not been investigated with regard to their in vitro drug susceptibility. In this study, we examine the susceptibility of genotype 2 strains from bovine mastitis and genotype 1 isolates recovered from cow-barn surroundings. The in vitro susceptibility of ten isolates and the type strain (SAG2063(T)) of P. zopfii genotype 1, and equal number of genotype 2 isolates and the type strain (SAG2021(T)) were assessed by E-test against amphotericin B (AMB), gentamicin (GM), kanamycin (KM) and itraconazole (ITZ). Results showed that P. zopfii genotype 1 isolates are more susceptible in vitro to AMB, GM and KM than those of genotype 2. Moreover, genotype 2 isolates and seven isolates of genotype 1, including the type strain, are not susceptible to ITZ (>10 μg/ml). Thus, drug susceptibility of P. zopfii differs between these two genotypes.
Insights
Prototheca zopfii genotype 1 strains are more susceptible to certain drugs than genotype 2 strains, which cause bovine mastitis. This difference in drug susceptibility between Prototheca zopfii genotypes is crucial for understanding and treating bovine mastitis.
Area of Science:
- Veterinary Mycology
- Antimicrobial Susceptibility Testing
- Bovine Mastitis Pathogenesis
Background:
- Prototheca zopfii is an alga responsible for bovine mastitis, leading to decreased milk production.
- Prototheca zopfii genotype 2 is implicated as the primary cause of bovine mastitis.
- Limited data exists on the in vitro drug susceptibility of Prototheca zopfii isolates.
Purpose of the Study:
- To investigate the in vitro drug susceptibility of Prototheca zopfii genotype 1 and genotype 2 strains.
- To compare the antimicrobial susceptibility profiles between genotype 1 and genotype 2 of P. zopfii.
Main Methods:
- E-test was employed to assess the in vitro susceptibility of ten genotype 1 and ten genotype 2 isolates, plus their respective type strains.
- Antimicrobial agents tested included amphotericin B (AMB), gentamicin (GM), kanamycin (KM), and itraconazole (ITZ).
Main Results:
- Prototheca zopfii genotype 1 isolates demonstrated higher in vitro susceptibility to AMB, GM, and KM compared to genotype 2 isolates.
- Both genotype 2 isolates and most genotype 1 isolates (including the type strain) exhibited resistance to itraconazole (ITZ).
Conclusions:
- Significant differences in in vitro drug susceptibility exist between Prototheca zopfii genotypes 1 and 2.
- These findings highlight potential variations in treatment efficacy for bovine mastitis caused by different P. zopfii genotypes.
