Studies were conducted on 27 Old World monkeys to determine their susceptibility to pathogenic strains (HB-1 and C-66) of Naegleria fowleri by intranasal, intravenous, or intrathecal inoculation of trophozoites. No clinically detectable disease resulted from either intranasal or intravenous inoculation, but 11 of 18 monkeys inoculated intrathecally succumed to acutely fatal meningoencephalitis, while the other 7 survived with no obvious permanent brain damage. Pathogenicity of N. fowleri appeared to be influenced by the strain virulence, growth phase, and cultural condition of the amebae, as well as age, immune competence, and other as yet unknown host factors.
The overall prognosis of primary amoebic meningoencephalitis remains poor. The results of this study support previous finding that amphotericin B is the most efficacious drug against the Naegleria species in in vitro testing. In additon, the methyl ester of amphotericin B, a new derivative, also appears to be an effective agent. Of the drug combinations studied, amphotericin B plus minocycline and amphotericin B plus tetracycline showed synergy. The clinical significance of these findings remains to be determined.A strain of Naegleria fowleri (HB-1) was tested in vitro for susceptibility to amphotericin B (AMB), the methyl ester of AMB, miconazole, minocycline, and tetracycline, both singly and in combination with one another. The mean minimal inhibitory concentrations (MICs), defined as an absence of cytopathic effect by amoebae on monkey kidney cell (MKC) monolayers, were, respectively: AMB, 0.024 ug/ml; methyl ester of AMB, 0.103 ug/ml; minocycline, 2.8 ,ug/ ml; miconazole, 6.25 lAg/ml; and tetracycline, 10.0 ,ug/ml. Synergism
One hundred Macaco mulatta, trapped in India and transported directly to
the California Primate Research Center, were surveyed for the prevalence of gastrointestinal
helminths. Trichostrongylus sp. was found in 86% of the animals, followed by Strongyloides
fulleborni (63%), Streptopharagus sp. (38%), Oesophagostomum sp. (23%) and Anatrichosoma
sp. (21%). Treatment with mebendazole and thiabendazole was efficacious against
all the intestinal nematodes, with the exception of mebendazole versus Streptopharagus sp.
Susceptibility to A. culbertsoni was studied in 15 Old World monkeys by intranasal, intravenous, or intrathecal inoculation of trophozoites. No clinically detectable disease resulted from either intranasal or intravenous inoculation, but 4 of 7 monkeys inoculated intrathecally succumbed to acutely fatal meningoencephalitis. Virulence of the ameba varied with cultural age of the inoculum. Size of inoculum, passages through animal tissues, and host-immune competence were other factors of consideration in pathogenicity of the ameba.
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