Peter J. Cook

Chlamydia pneumoniae Antibody Titers Are Significantly Associated With Acute Stroke and Transient Cerebral Ischemia : The West Birmingham Stroke Project

BACKGROUND AND PURPOSE Several studies have implied an association between Chlamydia pneumoniae and atherosclerosis. Our research was designed to investigate the association of this organism with strokes and transient cerebral ischemia. METHODS Antibodies to C pneumoniae were measured in 176 patients with stroke or transient cerebral ischemia and 1518 control subjects with noncardiovascular, nonpulmonary disorders. Acute infection or reinfection was defined by IgG > or =512 or IgM > or =8 or fourfold rise in IgG, and previous infection was defined by IgG 64 to 256 or IgA > or =8. Logistic regression was used to examine the influences of ethnic origin, age, sex, smoking habit, diabetes mellitus, steroid medication, and social deprivation on antibody levels. Some patients underwent CT and carotid ultrasound examinations and cholesterol, triglyceride, fibrinogen, and von Willebrand factor estimations. RESULTS We found that 13.6% of stroke/transient ischemic attack (TIA) patients and 5.7% of control subjects had antibody titers suggesting acute C pneumoniae (re)infection, while 32.4% of stroke/TIA patients and 12.7% of control subjects had titers suggesting previous infection (P<.05). Stroke/TIA patients differed from control subjects in their levels of acute and previous infection, with adjusted odds ratios of 4.2 (95% CI, 2.5 to 7.1) and 4.4 (95% CI, 3.0 to 6.5), respectively. These did not differ notably between strokes resulting from major nonhemorrhagic infarcts, small-vessel infarcts, or hemorrhage. Cholesterol, triglyceride, fibrinogen, and von Willebrand factor concentrations showed no apparent association with titers. CONCLUSIONS These data support the association of cerebral vascular disease with previous C pneumoniae infection and the association of stroke and transient cerebral ischemia with recrudescence of infection.

Chlamydia pneumoniae and asthma

BACKGROUND This study was designed to test the association of Chlamydia pneumoniae infection with asthma in a multiracial population, after adjustments for several potential confounding variables. METHODS Antibodies to C pneumoniaewere measured by microimmunofluorescence in 123 patients with acute asthma, 1518 control subjects admitted to the same hospital with various non-cardiovascular, non-pulmonary disorders, and 46 patients with severe chronic asthma, including some with “brittle” asthma. Acute infection or reinfection was defined by titres of IgG of ⩾512 or IgM ⩾8 or a fourfold rise in IgG, and previous infection by IgG 64–256 or IgA ⩾8. Logistic regression was used to control for likely confounders, including ethnic origin, age, sex, smoking habit, steroid medication, diabetes mellitus and social deprivation, on antibody levels. RESULTS Antibody titres consistent with acuteC pneumoniae infection were found in 5.7% of patients with acute asthma and 5.7% of control patients, while 14.6% of patients with acute asthma and 12.7% of control patients had titres suggesting previous infection. These two groups did not differ significantly. However, titres suggesting previous infection were found in 34.8% of patients with severe chronic asthma: the difference between this group and the control group was statistically significant with an adjusted odds ratio of 3.99 (95% confidence interval 1.60 to 9.97). CONCLUSIONS These data raise important questions about the previously demonstrated association of C pneumoniae infection with asthma, and suggest that future studies of this association should give particular attention to the presence or absence of a history of severe chronic asthma.

Chlamydia pneumoniae Antibodies in Severe Essential Hypertension

Several studies have implied an association between Chlamydia pneumoniae (C. pneumoniae) and cardiovascular disease. Our study was designed to determine whether this organism is associated with severe essential hypertension in a multiracial British population. Antibodies to C. pneumoniae were measured by microimmunofluorescence in 123 patients with chronic severe hypertension and 123 control subjects, matched for ethnic origin, age, sex, and smoking habit, admitted to the same hospital with various noncardiovascular, nonpulmonary disorders. Previous infection was defined by IgG 64 to 256, provided that there was no detectable IgM. Multiple regression analyses of matched and unmatched data were used to investigate the influences of antibody levels and potential confounding factors (ethnic origin, age, sex, smoking habit, diabetes mellitus, and social deprivation) on hypertension. A portion of the hypertensive patients underwent echocardiography, estimation of left ventricular mass index, and measurements of fibrinogen, D-dimer, and von Willebrand factor concentrations. Thirty-five percent of hypertensive patients and 17.9% of matched control subjects had antibody titers consistent with previous C. pneumoniae infection. The hypertensive patients differed significantly from their matched control subjects in their level of previous infection, with an odds ratio of 2.5 (95% confidence interval, 1.3 to 4.7). There were no significant differences in antibody levels between patients with left ventricular hypertrophy and those without it. Fibrinogen, D-dimer, and von Willebrand factor concentrations were not significantly associated with antibody levels. These data support an association of C. pneumoniae with severe essential hypertension. They provide no evidence of a predisposition to develop left ventricular hypertrophy in hypertensive patients with C. pneumoniae infection or of associations with hypercoagulability or endothelial dysfunction.

Concentration of amoxycillin and clavulanate in lung compartments in adults without pulmonary infection.

BACKGROUND--The efficacy of an antibiotic is usually predicted from serum levels and MIC90 values for likely pathogens, but in the lung tissue concentrations may be more informative. This study compares concentrations of amoxycillin and clavulanate in serum, epithelial lining fluid (ELF), alveolar macrophages, and bronchial mucosa in 15 adults. METHODS--Amoxycillin 500 mg and clavulanic acid 250 mg were given 1-2 hours before diagnostic bronchoscopy for haemoptysis or radiological abnormality. Mucosal biopsy samples were taken from macroscopically normal sites, alveolar macrophages harvested by lavage, and ELF volume derived from urea concentrations in bronchial lavage fluid and blood. Amoxycillin was assayed by inhibition of growth of Micrococcus lutea, and clavulanate (in serum, ELF, and bronchial mucosa) by inhibition of growth of Klebsiella pneumoniae; in macrophages clavulanate was measured by high performance liquid chromatography. RESULTS--The median concentrations in serum were 6.90 mg/l for amoxycillin and 5.25 mg/l for clavulanate. The median bronchial mucosal concentration of amoxycillin was 2.99 mg/l and of clavulanate was 1.65 mg/l; the median concentrations in ELF were 0.89 and 0.96 mg/l, and in macrophages 0 and 0.76 mg/l, respectively. In macrophages amoxycillin levels were undetectable in 10 of 14 subjects (71%); by contrast, only 6 of 14 subjects (43%) had no detectable clavulanate. CONCLUSIONS--Clavulanate levels exceeded quoted MIC90 values (around 0.25 mg/l) for Legionella pneumophila both in ELF and in macrophages. Amoxycillin-clavulanate may therefore have a clinical role in infections with Legionella pneumophila.

Chlamydia pneumoniae infection and ethnic origin.

OBJECTIVES To test the association of Chlamydia pneumoniae infection with ethnic origin. DESIGN A prospective study by micro-immunofluorescence of antibodies to C. pneumoniae in patients admitted to one hospital with a variety of non-pulmonary, non-cardiovascular disorders. SETTING A large district general hospital serving a multi-ethnic inner-city population in Birmingham, UK. SUBJECTS There were 1518 patients, 1061 of whom were Caucasian, 290 Asian and 167 Afro-Caribbean. Each of 169 Asians and 141 Afro-Caribbeans was matched with two Caucasians for age, sex, smoking habit, steroid medication and date of admission, and logistic regression methods were used to compare the effects on C. pneumoniae antibody levels of ethnic origin, these confounding variables, diabetes mellitus and social deprivation. OUTCOME MEASURES Serological evidence of acute C. pneumoniae infection or reinfection (defined by titres of IgM > or = 8, a four-fold rise in IgG or IgG > or = 512) and previous infection (IgG 64-256 or IgA > or = 8). RESULTS Results showed 4.8% of Caucasians, 6.6% of Asians and 10.2% of Afro-Caribbeans had antibody titres suggesting acute (re)infection; and 11.2% of Caucasians, 13.4% of Asians and 21.0% of Afro-Caribbeans had titres suggesting previous infection. On chi 2 analysis, the distributions of the three possible serological outcomes (acute, previous and no infection) differed significantly (p < 0.05) between the Afro-Caribbean and Caucasian groups, but not between Asians and Caucasians or between Afro-Caribbeans and Asians. After adjusting for possible confounding variables, odds ratios for Afro-Caribbean versus Caucasian origin were 5.5 (95% confidence intervals 2.0-15.0) for acute (re)infection and 1.9 (1.0-3.7) for previous infection. CONCLUSIONS Our results suggest that C. pneumoniae infection may be more prevalent among Afro-Caribbean than among Caucasian people, and that Asians may lie somewhere between them in this respect. The behaviour of this pathogen in different ethnic groups deserves further investigation. Future studies of this organism should give due attention to the ethnic origins of patients.

Simplified preparation of human arterial sections for PCR analysis of Chlamydia pneumoniae and human DNA.

AIMS: To investigate multiple techniques for the preparation of solid tissue for polymerase chain reaction (PCR) analysis, and to identify the most simple techniques for routine use in the laboratory. METHODS: Techniques for the preparation of arterial tissue samples including homogenisation, ultrafiltration, and treatments involving proteinase K, Gene Clean, lectin, and Fe3+ specific chelators were evaluated using the PCR to amplify both Chlamydia pneumoniae and human DNA. RESULTS: Treatment with either Gene-Clean or lectin and the Fe3+ specific chelator deferoxamine mesylate removed PCR inhibitors from tissue homogenates. Homogenisation followed by GeneClean treatment resulted in the amplification of C pneumoniae DNA from within a section of atherosclerotic carotid artery, implying that C pneumoniae elementary bodies had been disrupted. In eight further clinical samples from patients not known to have C pneumoniae infection, human DNA was amplified and no cross contamination was observed between samples. These samples contained no evidence of C pneumoniae by PCR. CONCLUSIONS: A simple preparation of solid tissue for PCR analysis, involving homogenisation followed by GeneClean treatment has been developed, and is effective for the amplification of both C pneumoniae and human DNA.