Biomedical subjects
Publications and source records attributed to K Bernard.
A case of pneumonia and acute tubular necrosis was caused by an initially unknown species of Legionella. The organism was later identified as Legionella maceachernii by a combination of cultural, biochemical, and serological methods along with a gas-liquid chromatographic profile.
Four strains of fastidious gram-negative rods, thought to be Capnocytophaga species (formerly CDC group DF-1 or Bacteroides ochraceus) or CDC group DF-3 on the basis of conventional phenotypic criteria, were also analyzed for cellular fatty acid (CFA) composition. It was found that the CFA compositions of these strains were qualitatively incorrect for those taxa. Subsequently, it was determined that all four bacteria were in fact aerotolerant strains of Leptotrichia buccalis, based on biochemical reactions, CFA composition, and lactic acid as the major end product of glucose fermentation. It is recommended that, in addition to conventional cultural and biochemical criteria, all strains of Capnocytophaga or CDC group DF-3 should also be tested for metabolic end products of fermentation and CFA composition as essential adjuncts for identification.
Respiratory deterioration accounts for the morbidity and mortality observed in patients with cystic fibrosis. The role of Legionella in this deterioration was determined in a 2-year prospective study of 49 patients with cystic fibrosis and 19 sibling controls. Sera were obtained from participants on enrollment and at quarterly intervals. Legionella antibodies were measured in parallel using an indirect fluorescent assay. No seroconversions were observed. Eleven of 49 patients with cystic fibrosis (22%) were seropositive compared to none of 19 siblings (P less than 0.05). Six of the 11 patients demonstrated high titers (greater than or equal to 1:512) that persisted throughout the study. Absorption with pools of various Pseudomonas species reduced the antibody titers such that only 3 remained positive after absorption. Legionella was not found to be an important cause of clinical deterioration during this study. The results of the absorption studies suggest that high titers to Legionella in this population are due to cross-reacting antibodies.
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