Classification and identification of the aetiological agents of primary amebic meningo-encephalitis, together with preliminary investigations of public health measures : a thesis presented in partial fulfillment of the requirements for the degree of Master of Science in Microbiology at Massey University

Abstract

The taxonomy of the aetiological agents of Primary Amebic Meningo-encephalitis (PAM) was investigated to determine the reliability of the common features of the three current schemes. It is concluded that the scheme of Singh & Das (1970) is the most suitable and should be generally adopted. The acceptance of one scheme will remove much of the confusion which characterizes the classification of these organisms. Current identification methods that differentiate between Naegleria gruberi (the non-pathogen) and Naegleria fowleri (the pathogen) were also investigated over a wider range of parameters than previously, to establish their relative usefulness. The conclusions of this investigation are presented in Tables XXII and XXIII. The controversial identification of the 1968 New Zealand cases (isolates BK & BL) as a Myxomycete by Mandal et al. (1970) was re-examined. Evidence is presented to demonstrate that they are N. gruberi. It was established that there was no general selection for the non-pathogen over the pathogen at 37°C as indicated by their respective QO2 values at 27°C and 37°C. That there is potential for adaptation to a range of temperatures was shown. The failure of chlorine as a disinfectant for these soil-amebae was also examined. The ineffectiveness of normal levels of chlorination was confirmed and therefore the use of NaCl and the basic dyes Malachite Green and Brilliant Green investigated. It was found that no amebae could survive a concentration of (1.5%)(W/V) of NaCl in axenic culture, of 1.5 µg/cm 3 of Malachite Green and of 3.0 µg of Brilliant Green.