Effect of age and vaccination on extent and spread of Chlamydia pneumoniae infection in C57BL/6 mice.

BACKGROUND: Chlamydia pneumoniae is an obligate intracellular respiratory pathogen for humans. Infection by C. pneumoniae may be linked etiologically to extra-respiratory diseases of aging, especially atherosclerosis. We have previously shown that age promotes C. pneumoniae respiratory infection and extra-respiratory spread in BALB/c mice. FINDINGS: Aged C57BL/6 mice had a greater propensity to develop chronic and/or progressive respiratory infections following experimental intranasal infection by Chlamydia pneumoniae when compared to young counterparts. A heptavalent CTL epitope minigene (CpnCTL7) vaccine conferred equal protection in the lungs of both aged and young mice. This vaccine was partially effective in protecting against C. pneumoniae spread to the cardiovascular system of young mice, but failed to provide cardiovascular protection in aged animals. CONCLUSIONS: Our findings suggest that vaccine strategies that target the generation of a C. pneumoniae-specific CTL response can protect the respiratory system of both young and aged animals, but may not be adequate to prevent dissemination of C. pneumoniae to the cardiovascular system or control replication in those tissues in aged animals.

Professionalism: orientation exercises for incoming osteopathic medical students and developing class vision statements.

The Philadelphia College of Osteopathic Medicine has developed an exercise to introduce professional ethics and behavior at the earliest stages of medical education. During orientation, each incoming class creates a class vision statement. After small group discussions on professional ethics, honesty, and responsibilities, representatives from each group collated student input and constructed a class vision statement reflective of student consensus on these issues. Each vision statement was recited as an oath during the white coat ceremony at the conclusion of the orientation program. Despite the fact that previous vision statements were unavailable to each incoming class, there were many commonalities among the statements created. Central elements of all vision statements include commitment to altruism, compassionate treatment of patients, and honesty and integrity in all professional interactions. Humility, the capacity to recognize and accept one's limitations in knowledge and skills, was also a key element in each statement. Three of four statements specifically recognized the teamwork and mutual respect that should be engendered among all members of the health care team. Each vision statement had prominent statements regarding the learning process during osteopathic medical school and acknowledged the importance of active and lifelong learning in the students' career paths. Student evaluation of this exercise has been positive, especially the recitation of the statement during the white coat ceremony. Results suggest that the development of a class vision statement represents a powerful mechanism for addressing the importance of professional attitudes, behaviors, and ethics at the earliest stages of medical education.

Age alterations in extent and severity of experimental intranasal infection with Chlamydophila pneumoniae in BALB/c mice.

The intracellular bacterium Chlamydophila ("Chlamydia") pneumoniae is a pathogen for several respiratory diseases and may be a factor in the pathogenesis of chronic diseases of aging including atherosclerosis and Alzheimer's disease. We assessed whether aging is coupled with increased burden of infection in BALB/c mice after intranasal infection by C. pneumoniae. Six- and twenty-month-old BALB/c mice were infected intranasally with 5 x 10(4) inclusion forming units (IFU) or 5 x 10(5) IFU of C. pneumoniae. Lung, brain, and heart tissue were analyzed for infectious C. pneumoniae and for Chlamydophila antigen by immunohistochemistry. At both doses, aging was associated with a decreased proportion of animals that cleared infection from the lung and greater burden of infectious organism within the lung. We observed dose-dependent spread to the heart/ascending aorta in animals infected with C. pneumoniae. In mice given 5 x 10(4) IFU, spread to the heart by day 14 was only observed in old mice. By day 28, all animals inoculated with 5 x 10(4) IFU showed evidence of spread to the heart, although higher C. pneumoniae titers were observed in the hearts from old mice. In mice inoculated with 5 x 10(5) IFU, spread of C. pneumoniae to the heart was evident by day 14, with no discernible age effect. C. pneumoniae was also recovered from the central nervous system (brain and olfactory bulb) of all mice by day 28 postinfection, with higher C. pneumoniae titers in old animals than in young animals. Our results suggest that infection with C. pneumoniae may be more severe in old animals.