Outbreak of Chlamydia pneumoniae infection in a Japanese nursing home, 1999-2000.

OBJECTIVE: To identify risk factors for infection and severe illness due to Chlamydia pneumoniae. METHODS: To identify risk factors for infection, we conducted a case-control study among nursing home residents who had onset of symptoms during December 1, 1999, to February 20, 2000. To identify risk factors for severe illness among nursing home residents, we conducted a retrospective cohort study. SETTING: A nursing home providing long-term and day care services for elderly patients in Japan.Participants. Fifty-nine residents and 41 staff members of a nursing home. RESULTS: The attack rates for respiratory illness were 53% (31 of 59) among residents and 22% (9 of 41) among staff. Infection was confirmed in 15 resident and 2 staff case patients by isolation of C. pneumoniae from nasal swab specimens. Fifteen resident case patients developed severe illness (ie, bronchitis, pneumonia, and hypoxia); one case patient died. The median age of resident case patients was 87 years. We could identify neither the source of the outbreak nor significant risk factors for infection and severe illness in residents. However, residents with a higher level of physical activity were more likely to become infected, whereas older residents (aged more than 85 years) and those with a lower level of physical activity were more likely to develop severe illness (P>.05). Contact with residents was a risk factor for infection in staff (relative risk, undefined; P=.04). CONCLUSIONS: C. pneumoniae can cause large outbreaks of infection and severe illness among elderly persons, and its transmission is likely to be enhanced by close contacts among people in nursing homes. Therefore, early detection of an outbreak by means of better surveillance, and subsequent isolation of patients, may be effective control measures.

Mechanisms of abnormal Q waves in hypertrophic cardiomyopathy assessed by intracoronary electrocardiography.

INTRODUCTION: To clarify the mechanisms of abnormal Q waves in hypertrophic cardiomyopathy (HCM), local epicardial electrical activities were assessed by intracoronary electrocardiography (ECG). METHODS AND RESULTS: Unipolar intracoronary ECG was recorded by introducing a guide wire for angioplasty into the left anterior descending artery (LAD) in 20 patients with HCM and 10 control subjects. Intracoronary ECG showed no Q waves in any control subjects. Intracoronary ECG showed no Q waves in 8 HCM patients without abnormal Q waves on surface ECG. In 12 HCM patients with abnormal Q waves on surface ECG, 4 showed Q waves on intracoronary ECG associated with regional wall-motion abnormalities, suggesting Q waves are formed by loss of electrical forces due to transmural myocardial fibrosis. The remaining 8 patients, who did not have Q waves on intracoronary ECG, showed greater thickening of the basal free wall than the apical free wall, with no wall-motion abnormalities. Intracoronary ECG was characterized by increased R or R' waves and prolonged R peak times at the proximal LAD, suggesting Q waves are formed by increased electrical forces of hypertrophied basal septal and/or ventricular free wall, unopposed by apical forces. CONCLUSION: The study findings provide evidence for two mechanisms of abnormal Q waves in HCM: (1) loss of electrical forces due to transmural myocardial fibrosis, and (2) altered direction of resultant initial QRS vector due to increased electrical forces of disproportionate hypertrophy of the basal septal and/or ventricular free wall, unopposed by apical forces.