Identifying non-capsulate strains of Streptococcus pneumoniae isolated from eyes.

Over six months 10 biochemically and physiologically atypical strains of Streptococcus pneumoniae were isolated from eye swabs. Conventional methodology showed that these strains possessed characteristics of both S pneumoniae and other alpha haemolytic streptococci. The use of sodium dodecyl sulphate - polyacrylamide gel electrophoresis (SDS-PAGE) enabled us to characterise these strains as S pneumoniae. Loss of the capsule seemed to be associated with atypical biochemical properties.

Evaluation of Malthus 128H microbiological growth analyser for detecting significant bacteriuria.

In a pilot study a prototype Malthus 128H microbiological growth analyser was used to study the growth of six commonly encountered urinary pathogens in a range of five different laboratory media. No single medium had been able to show acceptable conductance changes for all bacteria within five hours. Subsequently, the Malthus system, with fastidious anaerobe broth as the culture medium, was used to screen 500 consecutive clinical specimens of urine for significant bacteriuria. After two and a half hours the Malthus system detected 32 out of the 40 true positives and eight of the 44 contaminated urines. Increasing the detection time to five hours permitted the recognition of 39 true positives and 37 contaminated urines.

Amylase-binding as a discriminator among oral streptococci.

The ability of 51 strains, belonging to Streptococcus sanguis, 'S. mitior', S. oralis and related groups, to bind salivary amylase was studied. Most strains were grouped according to their DNA-relatedness and then compared using 14 phenotypic tests. S. mitis, 'S. mitior' and three relatively new groups of strains ('CR', 'MGH' and 'Tufted mitior') bound salivary amylase, while strains of S. sanguis and S. oralis did not. The ability of strains to bind amylase or not was remarkably consistent within groups and the test proved to be reproducible, rapid and easy to perform. Combination of the amylase-binding test with 6 other conventional physiological tests allowed the construction of a dichotomous identification key which correctly identified 95% of strains for which genetic data was available. These findings suggest that the ability of organisms to bind salivary amylase could become a key test in identification schemes for certain oral streptococci.

A computerised spreadsheet for audit of a microbiology laboratory.

The use of a microcomputer and spreadsheet software is described, to assist in the audit of a clinical microbiology laboratory. The costs of consumables for specimen types and their workload values were calculated. Together with knowledge of the annual number of requests, these were used as a basis for determining the minimum budget and staffing establishment required.

Identification of Enterobacteriaceae: report of the British Society for Multipoint Technology collaborative study.

Under the auspices of the British Society for Multipoint Technology, 84 strains of Enterobacteriaceae were identified by multipoint inoculation techniques in eight laboratories. Results were compared to assess the inter-laboratory reproducibility and reliability of each test. Identity of the test strains was also determined by use of two commercially produced kits. Most test strains were identified by the multipoint inoculation systems, which were cost effective and generally accurate, although some laboratories performed better than others. Reproducibility of some test results was variable.

Axial mode structure of a copper vapor pumped dye laser.

A search for lasers to be employed in the development of uranium isotope separation techniques led to the investigation of a copper vapor pumped tunable dye laser patterned after the concept developed by Hansch. This investigation revealed that although the time integrated spectral output covered approximately 1.3 GHz, which was the desired bandwidth, the time resolved spectral output included high visibility mode structure which fluctuated randomly from pulse to pulse. These fluctuations could significantly reduce the throughput efficiency of multiphoton photoionization isotope separation processes involving strongly inhomogeneously broadened transitions.