Phenotypic characteristics and lipopolysaccharides of human and animal isolates of Fusobacterium necrophorum.

As part of a collaborative study, six culture collection isolates and 50 coded isolates of Fusobacterium necrophorum were examined for the types of lipopolysaccharides (LPS) they contained, and to see if this related to their reactions in a range of phenotypic tests and their susceptibility to a panel of six antimicrobial compounds. The biotype B type strain, putative biotype B isolates and human isolates were predominantly coccobacillary, had rough type LPS and some of these isolates (8 of 26) required incubation for > 2 days to demonstrate lipase activity. The biotype A type strain, putative biotype AB isolates and most putative biotype A isolates (16 of 18) were predominantly rod-shaped, had either smooth LPS or low M(r) rough type LPS and all demonstrated lipase activity within 2 days. The other two putative biotype A isolates were coccobacillary and had rough type LPS, and one of these required incubation for > 2 days to demonstrate lipase activity. The results of these latter two isolates more closely resembled biotype B. A few isolates were asaccharolytic, but most fermented one or more of glucose, fructose, maltose and galactose. There was no correlation between fermentation pattern and LPS type, biotype or source of isolate (animal or human) but, with the exception of two abberant isolates, there was good correlation between cellular morphology, type of growth in liquid media and LPS type.

Preliminary evaluation of "Clearview Chlamydia" for the rapid detection of chlamydial antigen in cervical secretions.

Clearview Chlamydia (Unipath) is a rapid monoclonal antibody based latex immunodiffusion test for detecting chlamydial antigen in endocervical specimens. The assay does not require specialised equipment or extensive training and takes less than 30 minutes from sample to results. The clinical performance of Clearview Chlamydia was evaluated with 478 paired endocervical swabs from patients attending a genitourinary medicine clinic. In the first part of the study, 221 non-randomised specimens were tested by cell culture (1st swab) and Clearview (2nd swab) whereas in the second part of the study 257 randomised swabs were examined by Clearview, cell culture and immunofluorescence. The overall prevalence of chlamydial infection was 8.8% and the sensitivity, specificity, positive and negative predictive values for Clearview were 85.7%, 99.1%, 90% and 98.6%. The test requires further evaluation to establish its role in the management and control of chlamydial infection.

Swabs and swab-transport media kits in the isolation of upper respiratory bacteria.

The recovery of upper respiratory tract bacteria on laboratory media from a variety of swabs and swab-transport media kits was examined. Organisms studied included strains of Streptococcus pyogenes, Streptococcus pneumoniae, Staphylococcus aureus, Neisseria meningitidis and Haemophilus influenzae. Although a wide range of results was obtained with regard to variables such as the type of swab or swab-transport media kit used, the time of plating, the temperature of storage of swab-transport media kits, and the nature of the suspension of the organisms, it was generally noted that recovery of organisms was better from swabs held in their plastic containers prior to plating than from swabs held in transport medium.

Optimal methods for the isolation of groups A, B, C and G streptococci.

The recovery of beta-haemolytic streptococci on laboratory media over a 48-hour period was studied from a variety of swabs held in plastic containers only, and from those held in transport media, stored either at room temperature or at 4 degrees C. The best results were obtained from swabs not held in transport medium and of these plain cotton-wool swabs consistently produced optimal results. The percentage recovery over 48 hours was maintained satisfactorily only when the swabs were kept at 4 degrees C.

Survival of upper respiratory tract bacteria on cotton-wool swabs.

Plain, buffered cotton-wool swabs and albumen-coated cotton-wool swabs were prepared with known numbers of the following: Haemophilus influenzae, Streptococcus pneumoniae, Staphylococcus aureus, corynebacteria and Escherichia coli. Swabs were plated immediately (0 hours) after loading with a 0.1 ml standardised inoculum; each swab was plated out four times by streaking on both halves of two plates. At 0 hours recovery rates from first platings on solid media ranged from 3.3%-8.9%; from platings 1-4 ranges were 2.5%-5.7%. Both types of swabs gave similar results. The greater the delay in plating swabs at room temperature and 4 degrees C the lower was the recovery rate of H. influenzae and Strep. pneumoniae, though both species survived better on either kind of swab when these were held at 4 degrees C. There was a very small reduction in numbers of Staph. aureus from 24 to 48 hours but the recovery rate of corynebacteria was similar over the 48-hour period, at both room temperature and 4 degrees C. Twenty-four-hour counts of E. coli at room temperature were approximately five times greater than at 0 hours, and at 48 hours colonies were too numerous to count. At 4 degrees C, however, counts of E. coli fell during the 48-hour period.