Identification of fusobacteria in a routine diagnostic laboratory

A scheme for differentiating Fusobacterium spp. and Leptotrichia spp. from Bacteroides spp. was devised after examining 114 strains of fusobacteria and asaccharolytic bacteroides (17 reference strains and 97 clinical isolates). Sensitivity to a 300 micrograms/ml plate of phosphomycin and an acid reaction on a lysine plate were found to be reliable for differentiating Fusobacterium spp. and L. buccalis from Bacteroides. Using a short set of simple cultural and biochemical tests, isolates could be identified as F. necrophorum, F. necrogenes, F. nucleatum, F. varium or L. buccalis. These tests were: indole, lecithinase, phosphatase, DNase and gas production, aesculin and casein hydrolysis, greening of casein/methylene blue agar, nitrite reduction, bile tolerance and haemolysis on horse blood agar.     

Identification of Cryptococcus neoformans in a routine clinical laboratory

Summary Eight taxonomic tests were compared for their ability to distinguishCryptococcus neoformans from the non-pathogenic species ofCryptococcus. Eight isolates ofCryptococcus were obtained from the American Type Culture Collection and 43 isolates were obtained directly from human and natural sources. The tests which appeared to be most valuable to the routine diagnostic laboratory were growth at 37° C, characteristic growth on Guizotia seed agar and virulence for mice.     

Identification and characterization of a novel adhesin unique to oral fusobacteria

Fusobacterium nucleatum is a gram-negative anaerobe that is prevalent in periodontal disease and infections of different parts of the body. The organism has remarkable adherence properties, binding to partners ranging from eukaryotic and prokaryotic cells to extracellular macromolecules. Understanding its adherence is important for understanding the pathogenesis of F. nucleatum. In this study, a novel adhesin, FadA (Fusobacterium adhesin A), was demonstrated to bind to the surface proteins of the oral mucosal KB cells. FadA is composed of 129 amino acid (aa) residues, including an 18-aa signal peptide, with calculated molecular masses of 13.6 kDa for the intact form and 12.6 kDa for the secreted form. It is highly conserved among F. nucleatum, Fusobacterium periodonticum, and Fusobacterium simiae, the three most closely related oral species, but is absent in the nonoral species, including Fusobacterium gonidiaformans, Fusobacterium mortiferum, Fusobacterium naviforme, Fusobacterium russii, and Fusobacterium ulcerans. In addition to FadA, F. nucleatum ATCC 25586 and ATCC 49256 also encode two paralogues, FN1529 and FNV2159, each sharing 31% identity with FadA. A double-crossover fadA deletion mutant, F. nucleatum 12230-US1, was constructed by utilizing a novel sonoporation procedure. The mutant had a slightly slower growth rate, yet its binding to KB and Chinese hamster ovarian cells was reduced by 70 to 80% compared to that of the wild type, indicating that FadA plays an important role in fusobacterial colonization in the host. Furthermore, due to its uniqueness to oral Fusobacterium species, fadA may be used as a marker to detect orally related fusobacteria. F. nucleatum isolated from other parts of the body may originate from the oral cavity.     

Yellow fluorescence of fusobacteria

Yellow fluorescence was shown to be a common property amongst seven species of fusobacteria. Pigment production varied depending on the basal medium used and the addition of cysteine hydrochloride to basal media was shown to stimulate yellow pigment production.     

Identification of streptococci in a medical laboratory

A total of 965 cultures of streptococci received at a reference unit for identification were examined with API-20 Strep kits and also by established methods. The API method, although it needed to be supplemented with additional tests, largely overcame the difficulty that pyogenic streptococci are usually identified by their serological reactions and that biochemical tests are used for the identification of the other streptococci. Representatives of at least 24 established or possible species were identified.     

Identification of streptococci in a medical laboratory

A total of 965 cultures of streptococci received at a reference unit for identification were examined with API-20 Strep kits and also by established methods. The API method, although it needed to be supplemented with additional tests, largely overcame the difficulty that pyogenic streptococci are usually identified by their serological reactions and that biochemical tests are used for the identification of the other streptococci. Representatives of at least 24 established or possible species were identified.     

Observations on paraffin baiting as a laboratory diagnostic procedure in nocardiosis

The efficacy of paraffin bait technique in the isolation ofNocardia asteroides from clinical specimens has been investigated. In a comparative study 1091 clinical specimens, mostly sputa and bronchial aspirates collected from 639 patients of bronchopulmonary diseases and 11 of meningitis, were examined by paraffin baiting and the conventional technique. Thirty-six clinical specimens originating from 12 of the patients yieldedN. asteroides by the paraffin bait technique but only 4 by the conventional technique. Approximately 95 % of 125 sputum samples inoculated withN. asteroides yielded the pathogen by paraffin baiting as against 49 % by the conventional technique. Paraffin baiting was more productive than the conventional technique in the isolation ofN. asteroides from mixed suspensions with a number of fungi and bacteria. It is concluded that paraffin baiting can be profitably adopted as a suitable technique for the isolation ofN. asteroides from clinical specimens, such as, sputum, gastric lavage, etc., which are often contaminated. The technique has no particular advantage with non-contaminated specimens.This work forms a part of the Ph. D. thesis of S.K.M. submitted in 1971 to the University of Delhi, and was presented at the Vth meeting of ISHAM held in Paris from 5th–10th July, 1971.     

Detection of pulmonary tuberculosis; comparative value of routine radiologic examinations and routine laboratory procedures

The abnormalities disclosed by the usual laboratory diagnostic procedures (blood cell count and hemoglobin determination, sedimentation rate determination, urinalysis, and serologic test for syphilis) are compared with the number revealed by stereophotoroentgen chest examination in a series of 951 patients. The number of significant abnormalities uncovered by the routine stereophotoroentgen examination of the chest was comparable to the number disclosed by the usual laboratory procedures used in patient evaluation. Some form of radiologic examination of the chest should be included in the routine laboratory procedures required for patient evaluation.