Mycoplasma pulmonis genital disease: effect of rat strain on pregnancy outcome.

BACKGROUND AND PURPOSE: Mycoplasma pulmonis is a natural pathogen of the respiratory and genital tracts of rats. Differential susceptibility and severity of the respiratory form of the disease, known as murine respiratory mycoplasmosis (MRM), exist between rat strains. We now report that specific rat strains vary in susceptibility to genital tract infection and pregnancy outcome. METHODS: Specific-pathogen-free (SPF) female F344, LEW, Wistar (WIS) and Sprague Dawley (SD) rats were intravaginally inoculated with 3 x 10(7) colony-forming units (CFU) of M. pulmonis strain X1048 or sterile diluent, and allowed to breed at 10 days after inoculation. Pregnant dams and pups were necropsied within 24 hours of parturition. At necropsy, culture for M. pulmonis was performed on dam and pups, and adverse effects on pregnancy outcome were assessed by determination of the incidence of infertility, fetal resorption, stillbirths, changes in litter size, and pup birth weight. Blood from dams was collected prior to inoculation and at time of necropsy for measurement of IgM and IgG antibodies to M. pulmonis. RESULTS: At time of necropsy, WIS (50%) and SD (60%) dams had a higher frequency of M. pulmonis culture positivity in the genital tract than did LEW (22.2%) and F344 (17.6%) dams. Dams that were still infected with M. pulmonis at time of necropsy had various complications. The SD rats had the greatest degree of adverse effects on pregnancy outcome, which were: infertility, decreased litter size (P < or = 0.01), decreased pup birth weight (P < or = 0.01), increased frequency of resorptions, stillbirths (P < or = 0.05), and the highest rate of pup pulmonary infection (23.1%) (P < or = 0.001). Despite a 50% colonization rate, WIS dams were the least adversely affected. The WIS pups born from M. pulmonis. infected dams had slight decrease in birth weight, and only 6% had pulmonary infections. The LEW infected dams developed infertility and lower numbers of liveborn pups without evidence of vertical transmission. The F344 infected dams had lower numbers of liveborn pups that were smaller than their control counterparts, and none had pulmonary infections. None of the animals had detectable IgM and IgG antibodies to M. pulmonis before inoculation. At time of necropsy, all animals inoculated with M. pulmonis developed significantly (P < or = 0.001) higher amounts of M. pulmonis IgG and IgM antibodies, with SD rats developing the highest amounts (P < or = 0.005). CONCLUSIONS: Both F344 and LEW rats are more resistant to vaginal inoculation with M. pulmonis than are WIS and SD rats. However, only SD dams suffered severe adverse effects on pregnancy outcome. The SD dams also had the greatest IgM and IgG antibody response to M. pulmonis. Our studies clearly indicate differences among rat strains in their susceptibility to vaginal inoculation with M. pulmonis and in secondary complications associated with infection. This system may be a useful model for determining host-specific factors that influence the outcome of natural mycoplasmal infections of the genital tract.

Experimental genital mycoplasmosis: time of infection influences pregnancy outcome.

Genital infection of rats with Mycoplasma pulmonis causes adverse pregnancy outcome and can result in in utero spread of infection to the fetus. The current study was designed to determine whether the stage of pregnancy when infection occurs influences pregnancy outcome. Rats were inoculated with 3 X 10(7) CFU of M. pulmonis at 10 days prior to breeding (-10) or at gestational day (gd) 11 or 14 and were necropsied at gd 11, 14, or 18 or within 24 h of parturition (term). Control rats received sterile broth. M. pulmonis was isolated from the placenta, amniotic fluid, or fetal tissues only from rats infected prior to breeding (P < 0.001). All infected rats had significantly more loss of pups than did control rats (P < 0.006), but rats infected prior to breeding or at the beginning of the third trimester (gd 14) were much more likely to have fetal losses. Rats infected in the early second trimester after implantation (gd 11) did not experience severe losses. Litter sizes, total litter weight, and individual pup weight from all infected rats, regardless of gestational stage when infected, were significantly smaller than those of control rats (P < 0.001). On the basis of the results of this study, we conclude that the time of infection plays a major role in determination of pregnancy outcome and spread of infection from the genital tract to the respiratory tract.

In utero transmission of Mycoplasma pulmonis in experimentally infected Sprague-Dawley rats.

Genital mycoplasmosis is important as an animal model for the interaction between infectious agents and the host during pregnancy as well as in its own right as a confounding variable affecting research projects in which the rat is used as a model to study reproductive function and physiology. We report the in utero transmission of Mycoplasma pulmonis and the development of placentitis, amnionitis, and mild fetal bronchopneumonia in Sprague-Dawley rats. A minimum of 10 days prior to breeding, specific-pathogen-free female Sprague-Dawley rats were infected by intravaginal inoculation with 3 x 10(7) CFU of M. pulmonis X1048 or with an equal volume of sterile broth. Rats and fetuses were subjected to necropsy at days 11, 14, and 18 of gestation. M. pulmonis was able to invade the placenta, cross the placental barrier, and establish an amniotic fluid infection by gestational day 14. It was isolated from the oropharynx and lungs of fetuses at gestational day 18. The placenta was more frequently colonized than amniotic fluid, followed by the fetal oropharynx and lungs, supporting an ascending route of infection. Histopathological evidence also support an active infection, with lesions compatible with placentitis, amnionitis, and mild fetal bronchopneumonia. M. pulmonis can traverse the placenta, resulting in infection of the amniotic fluid and in utero transmission of the microorganism to the developing fetus.

Impact of experimental genital mycoplasmosis on pregnancy outcome in Sprague-Dawley rats.

Specific-pathogen-free (SPF) female Sprague-Dawley rats were infected by intravaginal inoculation with 3 x 10(7) CFU of Mycoplasma pulmonis X1048 in 0.1 ml of Frey's broth or with an equal volume of sterile Frey's broth. A minimum of 10 days postinfection, rats were bred to noninfected males. Rats were necropsied at days 11, 14, and 18 of gestation and within 24 h of parturition. Throughout pregnancy, at least 50% of rats remained infected in the lower genital tract. At parturition, the major site of colonization was the respiratory tract (P = 0.02). M. pulmonis was not isolated from any site of any control rat. Pregnancy outcome was adversely affected by infection with M. pulmonis. Infected rats had significantly smaller litter sizes at day 18 of gestation (P < or = 0.01) and at term (P < or = 0.004). No statistically significant differences among the gestational stages in infected rats were noted for litter size. Total litter weight is a reflection of individual pup weight and of the number of pups born. Therefore, it was obvious that infected rats would have a significantly lower (P < or = 0.008) total litter weight than noninfected controls. However, when individual pup weights were considered, infected pups (n = 49) also had significantly lower (P < or = 0.0001) birth weights than did noninfected controls (n = 68). The incidence of an adverse pregnancy outcome at term (stillbirths, macerated fetuses, or resorptions) was higher (P < or = 0.01) in infected rats than in noninfected control rats. No stillborn pups or macerated fetuses were observed in any control term rats (n = 5). All control rats had live-born pups. Three infected rats had no live-born offspring. Resorptions were more common in infected rats than in control rats (P < or = 0.01). The mean number of resorptions per rat was greater in rats which went to term than in rats necropsied during gestation, indicating that the severity of disease was progressive. The rat is frequently the laboratory animal of choice for a wide variety of reproductive studies, and the experimental parameters that are most often measured (litter size, pup weight, and neonatal survival) were all adversely affected by genital mycoplasmosis. Genital mycoplasmosis is important as an animal model for the interaction of infectious agents and the host during pregnancy as well as in its own right as a confounding variable affecting research projects which use the rat as a model to study reproductive function and physiology.

Comparison of the Hamilton Depression Rating Scale and the Geriatric Depression Scale: detection of depression in dementia patients.

The present longitudinal prospective study compared results from the Geriatric Depression Scale with those from the Hamilton Depression Rating Scale for 30 dementia patients. The criterion measure was presence of depression as indicated by the psychiatric diagnosis. The psychiatrist and physician's assistant made the Hamilton ratings while the psychology staff administered the Geriatric Depression Scale. The two measures were statistically unrelated from Times 1 and 2 (rs = .26 and .41). Eleven (37%) patients were depressed and nine received antidepressant medications. Sensitivity ratings were 82% and 9%, respectively, and specificity ratings were 88% and 92%, respectively. Possible explanations for the success of the Geriatric Depression Scale and lack of success of the Hamilton ratings in detecting depression in this population are discussed.

A psychogeriatric nursing assessment protocol for use in multidisciplinary practice.

The assessment of geriatric patients with psychiatric or neurobehavioral problems demands a multidisciplinary approach linking nursing, psychiatry, neurology, geriatrics, and internal medicine. While the medical disciplines have relatively well-established approaches to assessing psychogeriatric patients, nursing lacks a comprehensive assessment strategy that supports both nursing and multidisciplinary practice. This article describes the Psychogeriatric Nursing Assessment Protocol (Abraham, 1989) developed for use in a multidisciplinary geriatric neuropsychiatric outpatient clinic. The relationship of the protocol to psychiatric, neurological, geriatric, and medical assessments is discussed in an attempt to clarify the linkages of knowledge and care required for successful service delivery to geriatric patients with psychiatric or neurobehavioral problems, as well as to their families and formal and informal caregivers.