Biomedical subjects
Publications and source records attributed to A M Simitzis-Le Flohic.
The authors present the first three cases of keratitis with Acanthamoeba sp. which have been diagnosed in healthy persons. Two of them are children and in two cases there had been a local traumatism.
Many cases of human keratitis with Acanthamoeba sp. have a pseudo-herpetic appearance. The authors therefore evaluated the importance of co-infection with this virus in the onset of amoebic cornean lesions. After herpetic and amoebic co-infection rabbits showed severe cornean lesions, the viral aspect of cornea received a specific treatment. The amoebic co-infection progressed unchecked with severe lesions until day 37 p.i., in which trophozoites and cysts were numerous. The possible favourising role of HSV1 and Acanthamoeba sp. co-infection may exist in humans, just as it certainly exists in the rabbit.
A new case of Acanthamoeba keratitis in a young woman using contact lenses is reported. Although the patient strictly complied with decontamination rules, she developed a huge corneal abscess invading the anterior chamber. After a misleading initial phase, the diagnosis was suspected on clinical grounds and was confirmed by parasitologists. The infection followed a favourable course, thereby avoiding surgery and its unpredictable consequences, but an opaque speck remained in the centre of the cornea. This case illustrates a pathology which is getting less and less exceptional, even in France where such pathogens can be found in the water for normal household use. Subjects wearing contact lenses and who are particularly exposed should be warned of the risk of infection they incur. Doctors should be taught to bear this diagnosis in mind in order to guide parasitological investigations and to obtain confirmation as early as possible.
The amebic keratitis with Acanthamoeba are until now rare, but however increasing as their diagnosis is better, and the contact lens wearers more numerous. The authors present the clinical and parasitological features of cases they did diagnose since 1986. In the immunological sphere, the T4 lymphocytes were 20% less than the normal for the first patient, and the third one had a very low level of immunoglobulins A. In the evolution sphere, the first one did received a keratoplasty; the second one has been successfully treated with propamidine isethionate; for the third one, the treatment with propamidine isethionate was nonuseful and a keratoplasty which was finally performed did show off numerous amebic cysts. In the parasitologic sphere, Acanthamoeba polyphaga was isolated from the first case, Acanthamoeba quina from the second one and Acanthamoeba lugdunensis from the last one. These last two cases are the first which did permit to isolate these amoebae, morphologically near to the first species.
Propamidine isethionate eye drops is one of the treatments which are used against amebic keratitis with Acanthamoeba. Several strains of Acanthamoeba, having been tested with this drug during several weeks, did show off a resistance. The authors come to the conclusion that in vitro sensitivity must be examined and therapy must be perfect since the beginning.
The authors did study the experimental effects on Aedes aegypti ova of different Spiroplasma strains, isolated from mosquitoes in French Savoy and in Taiwan. The SP7 strain, from Armigeres subalbatus (Taiwan), demonstrates a true pathogenic effect on the larval evolution, without sex ratio modifications, nor bacterial transmission to the adult mosquitoes. The authors present their results and emphasize the difficult use of Spiroplasmas sp.
Spiroplasmas have been isolated previously from a number of blood-sucking arthropods, including ticks, horseflies, and deerflies. More recently, spiroplasmas were isolated from mosquitoes from the USA, France, and Taiwan. Spiroplasmas isolated from mosquitoes from France belong to at least three serogroups and are serologically different from one of the Taiwan isolates, Sp2. Our Ar 1343 strain is the prototype of a new serogroup (XIII). During 3 consecutive years (1983-85), the ecology of these spiroplasmas was studied in different biotopes near, and in, the Isère River Valley in Savoia, France. A total of 23 strains was isolated from four species or groups of mosquitoes (Aedes sticticus/vexans, Ae. cantans/annulipes, Ae. cinereus/geminus and Coquillettidia richiardii). Spiroplasmas were isolated only from female mosquitoes and only during June and July. An as yet unidentified virus was also isolated from three mosquito pools, one of which yielded spiroplasmas. Spiroplasma viruses were not detected. Antibody to our Ar 1357 isolate was found in 4 of 20 sera from cows living in the areas studied, but not in sera from wild rodents or in sera from rabbit or pigeon sentinels. Finally, preliminary results are presented on the effects of experimental infection of Ae. aegypti with the Ar 1357 isolated (serogroup XXII).
Explore the source record for details and available documents.
We did not succeed to show of true free living amoebic parasites in stools of 207 micromammals from Finistere area, while on the other side 17 stool cultures were positive. To explain this failure, we exposed A. culbertsoni to oxygen: the trophozoit stage offers astonishing resistance during 1 to 6 hours and under 1 to 36 ATA pressures. Thus the lack of intestinal amphizoic free living amoebae could be explained by their very high affinity for oxygen and their lack of growth in a medium without this gas.
A first study was conducted on 243 hydrophilic contact lenses: 65 were macroscopically abnormal and 100 were infected with fungi. Moreover on Sabouraud's medium with chloramphenicol, 30 bacterial strains were isolated of which 25 Pseudomonas sp. (10 Ps. cepacia) and 1 Serratia liquefaciens. Then a second study was conducted on 107 among the 243 lens solutions: the 50 of the B trade mark were spoiled with 12 X 10(7) bacteria/ml and the 57 of the C trade mark with 5 X 10(7) bacteria/ml. This quantitative bacterial difference was confirmed with a qualitative one: from B trade-mark 6 Pseudomonas aeruginosa strains were isolated and from C only one. The authors emphasize the importance of Ps. aeruginosa in corneal ulcers associated with contact lenses, of lens solution composition, and of preservative usefulness.
Explore the source record for details and available documents.
The authors investigated the high hydrostatic and gas (nitrogen and helium) pressure effects on the morphology, missing encysting process and mortality rate of Acanthamoeba culbertsoni trophozoïtes. These studies have been performed by the means of scanning electron microscopy (SEM). It has been possible to show that the modulus of dissolving of both gas in water and oil is insufficient to explain the very important volumetric changes. Thereafter it appears that there is clathrate compounds formation.
Explore the source record for details and available documents.
In order to verify the contribution of scanning electron microscopy to the taxonomic study of free-living amoebae, the authors studied at the encysted stage 21 strains of free-living amoebae representing 20 species (1 Naegleria gruberi, 1 Tetramitus rostratus and 18 Acanthamoeba sp). The method utilized is satisfactory for distinguishing the different genera. Using optical methods, it is possible to differentiate three groups (I, II, III) of Acanthamoeba, including 3, 10 and 5 species, respectively. The results obtained with scanning electron microscopy, however, are less precise. In particular, group II can be divided into only four sub-groups and group III into only two sub-groups and one species, A. culbertsoni. The method remains valid for group I.
During a preliminary study, from October 1975 until June 1976, we tried to find free-living limax amoebae in the waters proceeding from 6 systems which partly cover the wants of Brest and its bay (Finistère). From the 32 analysed samples, 19 were positive, of which 10 were able to grown at the first at 37 degrees C. The free-living amoebae belong to 3 genus: Harmanella, Vahlkampfia and Acanthamoeba. We have not found Naegleria species.
Explore the source record for details and available documents.
Explore the source record for details and available documents.
We tried to prove the part of the little savage mammalians as active intermediate hosts to the intestine level for some free-living limax amoebae of limax group. For this we participated to several trapping-season in Britanny and in Tunisia. From 273 samplings, we studied 224 with the results thereafter: the rodents are the first (213/224) and the 3 most frequent species are also the most often hosts: 20/128 A. sylvaticus, 9/58 C. glareolus and 4/16 M. spretus. There must be a double positive factor: life in burrow near the earth and meal type. The 78 samplings for which we checked the free-living amoebae by stool examination, are the most poor by culture: 2/78 (2.5 p. 100). This lack explains the negative stool examination. The isolated amoebae belong for 31/34 to the genus Acanthamoeba, of one potentially pathogenic: A. hatchetti. Moreover the Finistere biotop appears particularly poor (2.5 p. 100 carriers in front of 21 p. 100 in Ille-et-Vilaine and 24 p. 100 in Tunisia).