Difficulties Encountered in Pneumococcal Type Determination

Abstract

Specimens for pneumococcal type determination should be fresh and should contain no disinfectant. Labels on vials of diagnostic horse serum should indicate the dilutions best suited for macroscopic and microscopic agglutination as detd. by tests with all types of pneumococci. Rabbit serum for the Neufeld reaction should be tested with all types and only specific serum should be issued. The Neufeld reaction is the most rapid and reliable method for typing. The proper proportions of serum and sputum must be used for consistent results. Mouse inoculation may be employed if no reaction is obtained on direct examination. Peritoneal exudate may best be typed by the Neufeld method, care being taken that very small amounts of material are used. Cultural examination will show the relative proportions of different organisms present. An adequate lighting system for the Neufeld reaction is essential.