Birefringence control in close-spaced fused-fiber wavelength-division multiplexers: a comparison of three methods.

Three methods of controlling the polarization sensitivity of close-spaced fused-fiber wavelength-division multiplexers are analyzed. Resin-packaged, optimum-fusing, and twist-tuning techniques are compared. The twist-tuning technique is shown to be the favored method.

Problems associated with identification of Legionella species from the environment and isolation of six possible new species.

Following investigation of an outbreak of legionellosis in South Australia, numerous Legionella-like organisms were isolated from water samples. Because of the limited number of commercially available direct fluorescent-antibody reagents and the cross-reactions found with some reagents, non-pneumophila legionellae proved to be difficult to identify and these isolates were stored at -70 degrees C for later study. Latex agglutination reagents for Legionella pneumophila and Legionella anisa developed by the Institute of Medical and Veterinary Science, Adelaide, Australia, were found to be useful as rapid screening aids. Autofluorescence was useful for placing isolates into broad groups. Cellular fatty acid analysis, ubiquinone analysis, and DNA hybridization techniques were necessary to provide definitive identification. The species which were isolated most frequently were L. pneumophila, followed by L. anisa, Legionella jamestowniensis, Legionella quinlivanii, Legionella rubrilucens, Legionella spiritensis, and a single isolate each of Legionella erythra, Legionella jordanis, Legionella birminghamensis, and Legionella cincinnatiensis. In addition, 10 isolates were found by DNA hybridization studies to be unrelated to any of the 26 currently known species, representing what we believe to be 6 possible new species.

Relapse of antibiotic-associated colitis after vancomycin therapy.

Antibiotic-associated colitis, although occasionally fatal, is a disease which is considered to be self-limiting and non-recurring. Recently, specific treatment with oral vancomycin directed at the trigger organism, Clostridium difficile, has been shown to be effective. A case in which antibiotic-associated colitis was treated with vancomycin and subsequently recurred is described. The fact that such relapse can occur indicates that further evaluation of the efficacy of vancomycin is required.