Impact of microbiology practice on cumulative prevalence of respiratory tract bacteria in patients with cystic fibrosis.

Investigators participating in the Epidemiologic Study of Cystic Fibrosis project began to collect microbiological, pulmonary, and nutritional data on cystic fibrosis (CF) patients at 180 North American sites in 1994. Part of this study was a survey undertaken in August 1995 to determine microbiology laboratory practices with regard to pulmonary specimens from CF patients. The survey included a section on test ordering, completed by a site clinician, and a section on test performance and reporting, completed by each site's clinical microbiology laboratory staff. Seventy-nine percent of the surveys were returned. There was intersite consistency of microbiology laboratory practices in most cases. The majority of sites follow most of the CF Foundation consensus conference recommendations. There were differences in the frequency at which specimens for culture were obtained, in the use of selective media for Staphylococcus aureus and Haemophilus influenzae, and in the use of a prolonged incubation for Burkholderia cepacia. These variations in practice contribute to prevalence differences among sites and may result in differences in clinical care.

PCR ribotyping and endonuclease subtyping in the epidemiology of Burkholderia cepacia infection.

Because of conflicting data about hospital-based transmission of Burkholderia (Pseudomonas) cepacia, an important respiratory pathogen in cystic fibrosis (CF), we compared strains found in sputum, lung, or blood of 29 CF patients in our center from 1988 to 1994, studying the relationship between strain and hospital exposure of incident and that of prevalent cases. Exposure was defined as a concurrent hospital stay between a prevalent and an incident case. B. cepacia strains were determined by polymerase chain reaction (PCR) ribotyping and endonuclease subtyping. The 16S to 23S spacer regions of the bacterial ribosomal RNA (rRNA) genes were amplified by PCR, and the product-size patterns used to type each B. cepacia isolate. Endonuclease digestion of the PCR products provided length polymorphisms for subtyping. There were 17 incident events during the period from 1988 to 1994, 16 of which involved a single ribotype. These 16 ribotypes could be divided into five subtypes by endonuclease mapping. Four patients grew B. cepacia from the blood, with the organism being the same strain as found in the lung in each case. Case controls were obtained to evaluate risk factors for B. cepacia acquisition. Concurrent hospitalization with a prevalent case significantly increased the risk of acquisition. There was no association between length of hospitalization, length of exposure, or FEV1 and the risk of B. cepacia acquisition.

Lipid and steroid hydroperoxides as substrates for the non-selenium-dependent glutathione peroxidase.

The reduction of linoleic acid hydroperoxide catalysed by rat liver cytosol was previously shown to be catalysed by a selenium-dependent glutathione peroxidase. In contrast, the enzyme responsible in guinea-pig liver cytosol is not selenium-dependent and appears to be a glutathione transferase.