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Diagnosing Parasitic Infections
Published in Firza Alexander Gronthoud, Practical Clinical Microbiology and Infectious Diseases, 2020
Cystoisospora belli (formerly known as Isospora belli, Cyclospora cayetanensis and Cryptosporidium cause self-limiting watery diarrhoea in immunocompetent individuals which can last several weeks. Immunocompromised individuals are at risk of developing severe and prolonged infection with malabsorption and weight loss.
Pyrimethamine
Published in M. Lindsay Grayson, Sara E. Cosgrove, Suzanne M. Crowe, M. Lindsay Grayson, William Hope, James S. McCarthy, John Mills, Johan W. Mouton, David L. Paterson, Kucers’ The Use of Antibiotics, 2017
Bianca Graves, David Looke, M. Lindsay Grayson
The key clinical use of pyrimethamine has been in combination with sulfadoxine as an antimalarial, commonly referred to as Fansidar or abbreviated as S/P. However, the development of widespread resistance in Plasmodium falciparum has led to a decline in its use for treatment of falciparum malaria. It remains useful for intermittent preventive therapy for malaria in pregnancy (IPTp) and intermittent preventive therapy for malaria in infancy (IPTi). It also remains a key drug for treatment of toxoplasmosis, Pneumocystis jiroveci pneumonia, and diarrhea due to Cystoisospora belli, often in combination with non-sulfa compounds such as clindamycin (see Chapter 85, Clindamycin and lincomycin).
Viral infections
Published in Phillip D. Smith, Richard S. Blumberg, Thomas T. MacDonald, Principles of Mucosal Immunology, 2020
Sarah Elizabeth Blutt, Mary K. Estes, Satya Dandekar, Phillip D. Smith
Several principles govern the interaction between opportunistic pathogens and HIV-1 infection (Table 28.3). First, susceptibility to mucosal, as well as systemic, opportunistic infections is inversely related to the level of immunosuppression, and clearance of the infection usually occurs after restoration of immune function with antiretroviral therapy. For example, the presence of active cytomegalovirus infection is inversely proportional to the number of circulating CD4+ T cells, with mucosal cytomegalovirus-induced inflammation and ulceration usually occurring after the number of CD4+ T cells declines to less than 100 cells mm−3, indicating severe immunosuppression. Conversely, cytomegalovirus disease resolves with HAART-induced restoration of immune function. Second, replication of some opportunistic pathogens may enhance HIV-1 transcription and vice versa in dual-infected cells and in lymphoid tissue. For example, the bidirectional upregulation of Mycobacterium avium complex replication and HIV-1 transcription has been detected in dual-infected macrophages in lymph nodes. Bidirectional upregulation likely occurs in dual-infected immune cells in the mucosa. Third, the route of HIV-1 entry does not determine the site of mucosal infections. Thus, HIV-1 transmitted by the genital route can lead to opportunistic infections in the gastrointestinal mucosa and/or the genital mucosa. Fourth, the specific mucosal pathogen acquired reflects in part the pathogens endemic to a specific geographical area and the sexual practices of the HIV-1-infected host. For example, among HIV-1-infected people, Cystoisospora belli is more common in Africa and the Caribbean region than in the United States, and Histoplasma capsulatum is more common in the Mississippi and Ohio River valleys than other regions of the United States. Regarding the influence of sexual practices on mucosal infection, Chlamydia trachomatis proctitis, for example, occurs only in men who practice receptive anal intercourse.
Structure-activity relationships of Toxoplasma gondii cytochrome bc 1 inhibitors
Published in Expert Opinion on Drug Discovery, 2022
P. Holland Alday, Aaron Nilsen, J. Stone Doggett
Cytochrome (cyt) bc1 has proven to be a tractable drug target for the majority of veterinary and human apicomplexan pathogens. In addition to T. gondii, cyt bc1 inhibitors have been found to be effective across orders of the phylum Apicomplexa: Haemosporida, Plasmodia spp.; the Piroplasmida, Babesia spp., and Theileria equii; and the Eucoccidiorida, Sarcocystis neurona, Eimeria spp., Neospora caninum, and Besnoitia besnoiti [5–10]. Cryptosporidium, the human gastrointestinal parasite, is a notable exception. It lacks a mitochondrion with genes for enzymes of oxidative phosphorylation, including cyt b and instead contains mitochondrion-related organelles [11]. On the other hand, the human gastrointestinal parasites Cyclospora cayetanensis and Cystoisospora belli encode cyt b in their mitochondrial genomes, although cyt bc1 inhibitors have not been thoroughly evaluated for these diseases.
The impact of water crises and climate changes on the transmission of protozoan parasites in Africa
Published in Pathogens and Global Health, 2018
Shahira A. Ahmed, Milena Guerrero Flórez, Panagiotis Karanis
Waterborne protozoa (WBP) are a group of parasites that cause diarrheal diseases. Diversity of WBP can be found in water. Cryptosporidium spp. and Giardia duodenalis (intestinalis) took the lead among other protozoan parasites to account the majority of waterborne outbreaks (524, 344 outbreaks respectively) [10–12]. Whereas Acanthamoeba spp., Balantidium coli, Blastocystis spp., Cyclospora cayetanensis, Cystoisospora belli, Microsporidium spp., Naegleria spp., Sarcocystis spp., and Toxoplasma gondii are less reported parasites [10–12].
Validation and maintaining laboratory developed molecular tests compliant with ISO15189 for diagnosis of intestinal parasitic infections
Published in Expert Review of Molecular Diagnostics, 2022
The in silico specificity determines if primers and probes used to amplify and detect a target sequence are unique for the intended organism. Although false positive results will only occur if both primers and probe will anneal to the DNA of a nonintended organism, the efficiency of a PCR will decrease if one of the primers or probes will anneal to the DNA of another organism. Sequences of related and non-related organisms are obtained from the GenBank and by BLAST search of the primers and probes with exclusion of the target organism. When no relevant matches are found this is reported for each primer and probe sequence in the validation report. Suspicious matches are aligned with the target sequence together with the primers and probes assessed for their relevance. In some cases one can accept a certain degree of non-specificity for example if a PCR turns out to be genus- instead of species-specific. In Figure 2a and 2b, the alignment for a Cyclospora cayetanensis PCR and for an Ancylostoma duodenale PCR are given [9,10]. In both examples, the in silico analysis for specificity revealed that the primers and probes are not unique for the initially intended species and therefore do not meet the preset criterion. However, in both cases this is accepted with an adaptation in reporting the results to the clinic. In the first example results are reported as Cyclospora cayetanensis/Cystoisospora belli DNA detected or not detected and although the treatment for both infections is the same additional microscopy will be performed to confirm the presence of one of the two parasites. In the second example the result of the PCR is reported as Ancylostoma DNA detected or not-detected and thus resulting in a genus- rather than a species-specific result. Including Ancylostoma caninum within the current Ancylostoma genus PCR as screening assay followed by a multiplex Ancylostoma species-specific PCR will be considered in future work [11].