Report on the unusual presence of latent microorganisms in animals: a risk to research and health of employees?

摘要

We report the unusual finding of mobile spirochetal microorganisms with different morphologies and sizes, on dark-field microscopy of the blood of animals from the Vivarium of the Medical School of USP. The bacteria did not grow in common culture media, shows faint staining to Giemsa and silver-derived stains, and serologies and molecular tests were negative for Borrelia and Leptospira. Electron microscopy revealed the presence of microorganisms with Mycoplasma-like morphology and, due to its mobility, it was suggested that they represented Mollicutes of the genus Spiroplasma. Microorganisms with the same morphology were also observed in 15 out of 26 employees (57.6%) of the Vivarium of FMUSP; however, clinical and laboratorial exams indicated that those individuals were healthy. Additional studies undertaken at the Rheumatology Department of FMUSP demonstrated the presence of the same structures identified at the Vivarium in approximately 94% of the patients with Baggio-Yoshinary syndrome (BYS) and 20% of healthy individuals. Electron microscopy of the blood of BYS patients showed bacteria that shared similarities with Mycoplasma, Chlamydia, and Bacteroides. Since serologies and molecular tests were negative for those contaminants, and based on publications in the medical literature, it was suggested that those latent infectious agents were L-form bacteria, defined as cell wall deficient bacteria, assuming, therefore, Mycoplasma morphology and they are, for the most part, harmless to the host. We concluded that spirochetal microorganisms visualized in animals and employees of the Vivarium were non-pathogenic L-form bacteria from contaminants in the environment, regular infections, or endogenous microorganism from the normal saprophytic flora. On the other hand, spirochetal organisms identified in BYS, by preserving the capacity to invade cells in vitro, are potentially pathogenic and related to the etiology of BYS. We consider BYS as a novel Brazilian zoonosis caused by spirochetes adapted to their latent form, possibly due to bacterial mutations in response to ecologic and geographic conditions unique to Brazil.