Naegleria lovaniensis tarasca new subspecies, and the purepecha strain, a morphological variant of N. l. lovaniensis, isolated from natural thermal waters in Mexico.

Amoebae were isolated from a natural thermal water source in Michoacán, Mexico, in September 1986. Two 500-ml samples were taken from pools with water at 45 degrees C and 46 degrees C and concentrated at 2,000 g for 15 min. The sediment was seeded on nonnutritive agar plates and incubated at 42 degrees C. The isolates were axenized in bactocasitone-serum medium. The identification of the isolates was based on their morphology, total protein and isoenzyme patterns by agarose isoelectric focusing, serology, fine structure, agglutination with Concanavalin A, sensitivity to trimethoprim, capacity to kill mice, and their cytopathic effect in Vero cells. The results showed several morphophysiological, biochemical and serological differences between the isolates and the type strain Aq/9/1/45D of Naegleria lovaniensis. These remarkable differences provide sufficient evidence to consider one of the isolates a new subspecies, and the other one a morphological variant of N. l. lovaniensis, which can be differentiated from other Naegleriae by their morphology, biochemistry, serology and physiology. The authors propose the name tarasca for the subspecies and purepecha for the morphological variant.

Pathogenic amoebae in natural thermal waters of three resorts of Hidalgo, Mexico.

In a search for free-living amoebae, seven water samples from three thermal water bathing resorts in Tecozautla, Hidalgo, were analyzed during December 1984. The samples were concentrated by filtration and centrifugation, and inoculated later on monoxenic and axenic media. The identification of the isolates was performed by morphology and isoelectric focusing of isoenzymes and total proteins. Thirty-three strains of free-living amoebae belonging to the genera Naegleria, Acanthamoeba, and Willaertia were isolated. Twenty of these strains belonged to the Naegleria genus, 16 of them were classified as Naegleria spp., and 2 were classified as Naegleria lovaniensis. Noteworthy was the finding of two pathogenic strains of the species Naegleria australiensis. N. australiensis and N. lovaniensis may be considered good indicator organisms, since they live in the same environmental conditions as N. fowleri, the agent of primary amoebic encephalitis (PAM). On the other hand, amoebae other than Naegleria were isolated and identified as Acathamoeba castellanii (two strains), and Acanthamoeba lugdunensis (one strain), which proved to be pathogenic when tested in mice. Nine more pathogenic strains of the genus Acanthamoeba spp. were isolated together with one strain of Willaertia magna, a thermophilic nonpathogenic amoeba. The chlorination and periodical surveillance of water resorts like the one studied is recommended, in order to prevent the appearance of more cases of PAM or other human diseases associated with pathogenic Acanthamoeba spp.

Amoebae isolated from the atmosphere of Mexico City and environs.

A protozoological analysis was performed from June to August, 1982 to isolate small free-living amoebae from the atmosphere by using an air vacuum sampler and several filters. Monoxenic medium (nonnutritive agar plus Escherichia coli) and axenic medium (De Jonckheere, 1977) were used to culture the isolates. The species isolated included Naegleria sp. Alexeieff emend. Calkins, Acanthamoeba polyphaga Puschkarew, Vahlkampfia jugosa Page, Acanthamoeba astronyxis Ray and Hayes, Acanthamoeba castellanii Douglas, Acanthamoeba culbertsoni Singh y Das, Vahlkampfia ustiana Page, Saccamoeba stagnicola Page, Hyalodiscus sp. Hertwig and Lesser, Platyamoeba placida Page, Rugipes sp. Schaeffer, Vannella platypodia Gläser, Vahlkampfia russelli Singh, Vahlkampfia ovis Schmidt, and Leptomyxa flabellata Goodey. Among the species isolated Naegleria sp., A. polyphaga, A. culbertsoni, and A. castellanii include strains, known to be pathogenic in humans.

Klebsiella pneumonie como agente patógeno primario / Klebsiella pneumoniae as primary pathogenic agent

Se investigó la presencia de algunos factores de patogenicidad en cepas de Klebsiella pneumoniae. La prueba de adhesividad a células epiteliales fue positiva en muchas cepas, especialmente en las aisladas de urocultivo. Muchas cepas produjeron enzimas líticas, y se hicieron pocas pruebas de invasividad, que fueron negativas, pero estos resultados no tienen valor estadístico. El polisacárido capsular de las cepas probadas es capaz de inhibir la fagocitosis tanto de polimorfonucleares como de macrófagos peritoneales de ratón, y a bajas concentraciones induce la formación de anticuerpos y complejos inmunes en conejo. También se encontraron cepas productoras de enterotoxinas. La presencia de estos factores de patogenicidad permite que por lo menos algunas cepas sean capaces de producir enfermedad en huéspedes no comprometidos