Culture diagnosis of meningococcal carriers: yield from different sites and influence of storage in transport medium.

Different specimens and techniques have been used in the diagnosis of carriers of Neisseria meningitidis, reflecting the uncertainty about the optimal diagnostic procedure. In the present investigation the culture yield of meningococci from throat specimens was compared to that from nasopharyngeal speimens in 178 persons: 44 carriers were diagnosed. All of them were detected by culture of throat specimens while 34% of them would have remained undiagnosed if only nasopharyngeal specimens had been examined. Storage of throat specimens in a transport medium for 24 hours before culture gave a negative culture for meningococci in 41% of the carriers. This loss was surprisingly high, the reasons for which are discussed.