Studies on pneumococci isolated from children in the Sheffield area.

The isolation of the pneumococcus (Streptococcus pneumoniae) was improved, and gave large mucoid colonies, when incubated in an anaerobic environment containing extra CO2. Both reduction of oxygen tension, with a reduction in the formation of peroxides, and a variable requirement for CO2 were necessary for optimal recovery of strains from children. During a four year period 1736 pneumococci isolated from samples at the Children's Hospital, Sheffield were serotyped, their requirement for CO2 and sensitivity to antibiotics were collated with patients details. This information was analysed for patterns both in health and disease as a background to clinical management and the introduction of vaccination in high risk patients. Serotyping of strains by co-agglutination of sensitised protein-A particles, was quicker and as sensitive as crossed immuno-electrophoresis (CIE), without requiring the complex CIE equipment. The increased and more active growth obtained under anaerobic conditions enhanced detection of pneumococcal enzymes, including sugar fermentation. New specific substrates, e.g. the APIZYM system, and those linked to nitrophenyl compounds were found to be applicable to the pneumococcus. A second new area of investigation, the differentiation of the pneumococcus by its sensitivity to a range of dye substances, was discovered and developed. Further unique differences were seen in the shape and colour of colonies on Mitis salivarius agar, CO2 requirement, haemolysins and sensitivity to tetracycline. Another antibiotic, mecillinam, was found for the practical recognition of penicillin-tolerant strains as an alternative to the use of cloxacillin for this purpose. Much of the work in this study has not previously been reported and should form the basis of a number of new approaches and may lead to a scheme, at present not available, for the differentiation and characterisation of the pneumococcus beyond the capsular serotype.