Development of a new multiplex PCR to detect fecal coccidian parasite.

BACKGROUND: Cryptosporidium spp., Cystoisospora belli and Cyclospora cayetanensis are common intestinal coccidian parasites causing gastroenteritis. The clinical presentation caused by each parasite is indistinguishable from each other. Uniplex polymerase chain reaction (PCR) for these three groups of intestinal coccidian parasites was developed by us in our laboratory. Thereafter, we planned to develop a single-run multiplex polymerase chain reaction (mPCR) assay to detect Cryptosporidium spp., C. belli and C. cayetanensis simultaneously from a stool sample and described it here as coccidian mPCR. METHODS: New primers for C. belli and C. cayetanensis were designed and uniplex PCRs were standardized. The coccidian mPCR was standardized with known positive DNA control isolates. It was validated with 58 known positive and 58 known negative stool samples, which were previously identified by uniplex PCR. RESULTS: The coccidian mPCR was standardized with earlier primers designed by us for Cryptosporidium spp. and C. cayetanensis, and a newly designed primer for the internal transcribed spacer-1 (ITS-1) gene for C. belli. The coccidian mPCR was 92.1% sensitive for Cryptosporidium spp., and 100% sensitive for C. belli and C. cayetanensis each, when tested on 116 known samples. It was 100% specific for all intestinal coccidian parasites. Two representative PCR products of the newly designed ITS-1 primer for C. belli were sequenced and submitted to the GenBank, which best match with the sequences of C. belli. CONCLUSION: A highly sensitive, specific, cost-effective, indigenous, single-run coccidian mPCR has been developed, which can simultaneously detect Cryptosporidium spp., C. belli and C. cayetanensis.

Molecular detection of Cystoisospora belli by single-run polymerase chain reaction in stool samples.

INTRODUCTION: Cystoisospora belli (C. belli) is the only pathogenic species of the Cystoisospora genus responsible for severe diarrhea in immunocompromised patients. Most common microscopic method of diagnosis is less sensitive due to intermittent shedding of oocysts. We developed a new single-run polymerase chain reaction (PCR)-based diagnostic assay for C. belli. METHODS: A new single-run PCR-based diagnostic assay was standardized for the detection of C. belli. Diagnostic reproducibility and repeatability of the PCR assay were evaluated. A cross-sectional analytical study was done on a total of 354 stool samples collected from 331 immunocompromised patients with diarrhea. All the stool samples were tested for the presence of oocysts of C. belli and were also tested by our new PCR assay for C. belli. Three of the representative PCR products were confirmed by sequencing. Fisher's exact test was used to compare the two proportions. RESULTS: Microscopy detected C. belli in 11/354 (3.1%) of stool samples, and the new PCR-based assay detected C. belli in 16/354 (4.5%). The new single-run PCR-based assay detected C. belli in all the stool samples which were tested positive by microscopy and additionally detected C. belli in five stool samples. The developed PCR assay detected statistically significant proportion of C. belli (p < 0.001) as compared to microscopy. The 795 base pair PCR product from one microscopy positive stool sample and two microscopy negative stool samples were confirmed by sequencing. CONCLUSION: Our newly developed single-run PCR-based detection assay for C. belli is robust and reproducible. It may be used for molecular diagnosis of cystoisosporiasis especially in transplant, pediatrics, and human immunodeficiency virus (HIV) positive patients.

Uncommon and fatal case of cystoisosporiasis in a non HIV-immunosuppressed patient from a non-endemic country.

Cystoisospora belli (previously known as Isospora belli) is a tropical coccidian parasite sometimes leading to severe diarrhea in immunocompromised patients. Here we describe a fatal case of cystoisosporiasis in a non HIV-immunocompromised 71-year-old female with no recent travel history. Infection was either latent or potentially caused by the consumption of contaminated imported food from Asia. Diagnosis was made by microscopical detection of numerous C. belli oocysts in stools without specific staining. Treatment with TMP-SMZ slightly improved diarrhea within 3days, but dehydration subsequently led to acute decompensated heart failure and a fatal evolution. This report illustrates the possibility of severe cystoisosporiasis in non HIV-immunocompromised patients in a non-endemic country and highlights the risk of transmission through imported contaminated food consumption.

Infección por Cystoisospora belli en pacientes con VIH: análisis de casos con diferente evolución clínica / Cystoisospora belli infection in HIV patients: analysis of cases with different clinical evolution

Resumen Introducción: La infección por Cystoisospora belli es una de las causas más frecuentes de diarrea acuosa en pacientes con infección por VIH y ocasiona altas tasas de morbilidad y mortalidad. Métodos: Se realizó un estudio retrospectivo en pacientes infectados con VIH y diarrea por C. belli. Características clínicas y de laboratorio fueron recolectadas mediante el análisis de historias clínicas. Resultados: Se identificaron siete casos. Cuatro presentaron diarrea recurrente a pesar de recibir profilaxis secundaria con cotrimoxazol y tratamiento específico, dos de los cuales tuvieron buena respuesta viral e inmunológica al tratamiento anti-retroviral de gran actividad (TARGA) al momento del diagnóstico y tratamiento antiparasitario. Mientras que, los tres restantes no recibían profilaxis, tampoco TARGA (dos de ellos), pero respondieron bien al tratamiento. Conclusiones: C. belli es causa importante de diarrea en pacientes VIH con TARGA y profilaxis, pudiendo tener distinta evolución clínica. Sugerimos que la infección persistente puede ser debido al fallo farmacológico por causas intrínsecas o extrínsecas al parásito, o a defectos en la restauración del sistema inmune intestinal, o ambos.

Introduction: Cystoisospora belli infection is one of the most important causes of watery diarrhea in patients with HIV and causes high rates of morbidity and mortality. Methods: A retrospective study was conducted in patients with HIV and diarrhea by C. belli. Clinical and laboratory characteristics were collected by analyzing clinical records. Results: Four had recurrent diarrhea despite receiving secondary prophylaxis with cotrimoxazole and specific treatment, two of which had a good viral and immunological response to highly active antiretroviral therapy (HAART) at the time of diagnosis and antiparasitic treatment. While the remaining three did not receive prophylaxis, neither did HAART (two of them), but they responded well to treatment. Conclusions: C. belli is an important cause of diarrhea in HIV patients on HAART and prophylaxis, being able to have different clinical evolution. We suggest that persistent infection may be due to drug failure by intrinsic or extrinsic to the parasite causes, or to defects in restoration of the intestinal immune system, or both.

Intestinal coccidian parasites as an underestimated cause of travellers' diarrhoea in Polish immunocompetent patients.

Intestinal coccidian parasites are intracellular protozoa most frequently transmitted during food-borne and water-borne infections. This group of parasites is responsible for acute diarrhoeal illnesses especially among immunocompromised patients. However, they are more frequently detected in immunocompetent individuals including travellers, and they should also be considered as important etiologic factors of travellers' diarrhoea. We examined 221 immunocompetent patients hospitalized due to acute or chronic diarrhoea and other gastrointestinal symptoms after returning from international journeys to hot climates. A basic microscopical examination and acid - fast staining of stool samples was performed. Each patient was also a part of the epidemiological investigation to define potential risk factors of tropical gastrointestinal infections. Intestinal coccidiosis was confirmed in 12 out of 221 successively hospitalized patients (5.4%). The most common coccidian parasite was Cryptosporidium spp., detected in nine Polish travellers (4.1%). Cyclospora spp. was diagnosed in three cases (1.4%), including two mixed infections with Cryptosporidium spp., and Cystoisospora spp. in two other cases (0.9%). The study has revealed that intestinal coccidian parasites are a significant threat to immunocompetent travellers and should be always considered in the differential diagnosis of gastrointestinal disorders. Therefore, it is necessary to perform specialized diagnostic methods for the detection of Cryptosporidium spp., Cystoisospora spp., and Cyclospora spp. oocysts in reference parasitology laboratories. Clinical observations demonstrated simultaneously an insufficient level of knowledge in Polish tourists concerning the main risk factors of intestinal parasitic diseases during international travels, particularly to developing countries with lower economic and sanitary conditions.