Selective identification of the pathogenic E, histolytica in fresh stool samples using poolymerase chain reaction [PCR]

Stool samples from 93 individuals clinically presumed to have intestinal amoebiasis and subjected to microscopic examination and DNA extraction were collected. The PCR amplification was performed using two sets of primers that differentiated between pathogenic and nonpathogenic Entamoeba DNA. Of the 93 clinically positive cases, 51 were positive by microscopy, while 53 were detected by PCR as having DNA specific for either E. histolytica/ E. dispar. A specificity of 85.71% and a sensitivity of 92.15% were detected by PCR compared wit h microscopy. Among 53 PCR positive specimens, 3 different DNA sequences were demonstrated [8 specimens had DNA sequences specific of E. histolytica, 31 with DNA specific for E. dispar and 14 specimens had mixed DNA sequences for E. histolytica and E. dispar]. PCR was found to be a sensitive and a specific tool

Possible mechanism[s] for cryptosporidial diarrhea: parasitologic and physiopathologic studies in experimental animals

The present work was planned to study the possible mechanism[s] of diarrhea in cryptosporidiosis Stool eluates and intestinal homogenates from naturally and experimentally infected animals together with purified sporozoites were examined utilizing using chamber to demonstrate their possible enterotoxic effects Besides the histopathological changes in experimentally infected mice were studied to assess the possible underlying mechanism[s] of diarrhea in cryptosporidiosis. Characterization of the enterotoxic activity associated with cryptosporidiosis may have a great impact on the development of effective strategies for its treatment. The results of the present study revealed that in intestinal cryptosporidiosis enterotoxic substances are secreted which likely induce diarrhea. They induce an increase in the transepithelial potential difference [DIsc] to reach its maximum after 15 minutes and then slowly decrease to reach the baseline after 55 minutes [for stool eluates] and 35 minutes [for intestinal homogenates] On the other hand the purified sporozoites showed an increase in DIsc after 9 minutes and then a decrease after that to become maintained at relatively high level. The enterotoxins were found to be time and dose dependent and heat labile. The osmotic gap showed that the mechanism of diarrhea is rather secretory. In experimentally infected mice, shedding of oocysts first appeared in stools 3 days postinoculation [PI], reaching a peak 9 days [PI] and disappeared 15 days PI. Although the infected mice showed mild to severe degree of intestinal inflammation [marked villous atrophy and crypts hyperplasia], the stool was semiformed. Besides, the present study showed marked validity of mouse as an in vivo model to study the pathophysiology of cryptosporidial diarrhea. This model is inexpensive and serves as a suitable alternative to neonatal calves for efficient oocyst propagation

enterotoxic activity of 18-20 kDa cryptosporidium parvum secretory coproantigen [CCA 18-20 kDa]

An 18-20 kDa Cryptosporidium coproantigen [18-20 CCA] had been detected in the stool of infected humans and calves. A purified, electroeluted and concentrated 18-20 kDa antigen was tested in Ussing chamber. Electric parameters were tested before and after the addition of this antigen. A significant increase in the short circuit current [Isc] was detected. The enterotoxic effect of 18-20 kDa CCA was time and dose dependent, heat labile and CI- dependent. The detected change in the short circuit was not detected when the 18-20 kDa antigen was incubated with its monospecific antibodies. These results indicated an enterotoxic activity of the 18-20 kDa antigen secreted from the released parasite and detected in stool of infected humans and calves. Additionally, they may help in developing an appropriate anti-secretory therapy for the intractable diarrhea caused by cryptosporidiosis

Immunofluorescent detection of both giardia lamblia and cryptosporidium parvum using anti-cryptosporidium oocyst antibodies

In the present work, a polyspecific anti-cryptosporidium oocyst antibodies was used for simultaneous detection of both parasites in human stool. Known positive formalinized human stool specimens of Giardia sp. [n = 10], Cryptosporidium sp. [n=7] mixed infection [n=3] and negative specimens [n = 20] were tested using direct fluorescent technique against the developed antibodies. All positive stool samples for Cryptosporidium and 9 out of 10 Giardia samples or each alone showed fluorescence with variable intensities, while no negative sample harbored other parasites had fluorescence. This newly used polyspecific antibodies offer the advantages of screening of a large number of patients, particularly in outbreaks. Additionally, it represents a cheaper alternative for the most sophisticated and costly immunoassay kits using the monoclonal antibodies with more or less the same diagnostic potentials