ABSTRACT
Mycoplasma pulmonis is the Mycoplasma most frequently encountered in laboratory animal bacteriology. In most individual cases, the sole presence of this agent in the host causes either mild symptoms or no symptoms at all. However, when complicated with other infectious agents, such as Pasteurella pneumotropica4 or various viruses,5 as well as environmental inducers such as raised ammonia levels,6 disease symptoms may become more severe. It has been claimed that it also exacerbates symptoms of
13.1 Introduction ........................................................................................... 233 13.2 Mycoplasma ............................................................................................. 233
13.2.1 Impact on the host .................................................................... 233 13.2.2 Characteristics of the agent ..................................................... 235
13.3 Acholeplasma ........................................................................................... 238 References ........................................................................................................ 239
infection with cilia-associated respiratory (CAR) bacillus, but this does not seem to be the case for all strains of M. pulmonis.7 Mycoplasma pulmonis is more frequently found in rats than in mice.8 The fraction of laboratory rodent colonies infected currently is less than 1%,8-10 but 90-100% of pet rats are seropositive,11 which indicates a risk also for laboratory rodents. In rats, it causes snuffles, ruffled hair coat, bronchopneumonia, and arthritis, mostly in a mild form. In addition, it colonizes genitals of both males and females,12 and at least in the latter, it may affect reproduction. Even in the absence of clinical symptoms, M. pulmonis may be hazardous to experiments. It may raise the incidence of respiratory tract tumors,13 decrease the cellular and humoral immune response,14 decrease the severity of adjuvant arthritis,15 and reduce the incidence of diabetes mellitus type 1 in biobreeding rats. In mice, clinical symptoms are similar to rats,16 and in C57BL/6 mice, it may raise the proinflammatory cytokine level and enhance the metastatic capability of melanoma cells.17 Mycoplasma pulmonis may colonize humans in contact with infected animals, which probably does not cause disease but is important for the spread of the agent.18
