Biosafety and biosecurity requirements for Orientia spp. diagnosis and research: recommendations for risk-based biocontainment, work practices and the case for reclassification to risk group 2

Gaps and inconsistencies in the current knowledge and implementation of biosafety and biosecurity practices for rickettsial pathogens

INTRODUCTION

Rickettsia spp. and Orientia spp. are the causes of neglected infections that can lead to severe febrile and systemic illnesses in humans. Implementing proper biosafety practices when handling these pathogens is crucial to ensure a safe and sustainable work environment. It is essential to assess the current knowledge and identify any potential gaps to develop effective measures that minimise the risk of exposure to these pathogens. By doing so, we can establish a comprehensive framework that promotes safety, mitigates hazards, and safeguards the well-being of personnel and the surrounding community.

METHODS AND RESULTS

This review aimed to synthesise and determine the evidence base for biosafety precautions for Rickettsia spp. and Orientia spp. pathogens. Enhancing our understanding of the relative infectious risk associated with different strains of Rickettsia and Orientia spp. requires identifying the infectious dose of these pathogens that can cause human disease. The application of risk groups for Rickettsia and Orientia spp. is inconsistent across jurisdictions. There is also incomplete evidence regarding decontamination methods for these pathogens. With regards to Orientia spp. most of the available information is derived from experiments conducted with Rickettsia spp.

CONCLUSIONS

Rickettsia and Orientia spp. are neglected diseases, as demonstrated by the lack of evidence-based and specific biosafety information about these pathogens. In the case of Orientia spp., most of the available information is derived from Rickettsia spp., which may not be appropriate and overstate the risks of working with this pathogen. The advent of effective antibiotic therapy and a better understanding of the true hazards and risks associated with pathogen manipulation should inform decisions, allowing a sustainable and safe work environment.

Maximization of Siderophores Production from Biocontrol Agents, Pseudomonas aeruginosa F2 and Pseudomonas fluorescens JY3 Using Batch and Exponential Fed-Batch Fermentation

Twenty fluorescent Pseudomonas isolates were tested for their ability to produce siderophores on chrome azurol S (CAS) agar plates and their antagonistic activity against six plant pathogenic fungal isolates was assessed. Scaling-up production of siderophores from the promising isolates, P. aeruginosa F2 and P. fluorescens JY3 was performed using batch and exponential fed-batch fermentation. Finally, culture broth of the investigated bacterial isolates was used for the preparation of two economical bioformulations for controlling Fusarium oxysporum and Rhizoctonia solani. The results showed that both isolates yielded high siderophore production and they were more effective in inhibiting the mycelial growth of the tested fungi compared to the other bacterial isolates. Exponential fed-batch fermentation gave higher siderophore concentrations (estimated in 10 µL), which reached 67.05% at 46 h and 45.59% at 48 h for isolates F2 and JY3, respectively, than batch fermentation. Formulated P. aeruginosa F2 and P. fluorescens JY3 decreased the damping-off percentage caused by F. oxysporum with the same percentage (80%), while, the reduction in damping-off percentage caused by R. solani reached 87.49% and 62.5% for F2 and JY3, respectively. Furthermore, both formulations increased the fresh and dry weight of shoots and roots of wheat plants. In conclusion, bio-friendly formulations of siderophore-producing fluorescent Pseudomonas isolates can be used as biocontrol agents for controlling some plant fungal diseases.