Cryptosporidium parvum sporozoite staining by propidium iodide
1INSERM U80 CNRS URA 1177 UCBL, Hôpital E. Herriot, Lyon, France.
Abstract:
Modified Ziehl-Neelsen (ZN) acid-fast stain is the usual method for detection of Cryptosporidium oocysts in feces. Propidium iodide permitted us to stain free or intra-oocyst sporozoites. With the ZN method only 3-5% of the oocysts purified from three human and one experimentally infected lamb dichromate-preserved feces were stained by carbol fuchsin. These fuchsin-stained oocysts were free of intact sporozoites as identified by propidium iodide staining. Treatment with 10% formalin or 0.5% sodium hypochlorite increased the percentage of acid-fast stained oocysts and thus the sensitivity of acid-fast staining. Treatment with sodium hypochlorite induced intra-oocyst sporozoite alterations as demonstrated by flow cytometric analysis of the oocysts' DNA content. Propidium iodide staining of fixed oocysts is a simple and rapid method to visualize sporozoites and to assess oocyst preservation after different treatments.
Insights
Modified Ziehl-Neelsen staining for Cryptosporidium oocysts is improved by chemical treatments. Propidium iodide staining confirms treatment effectiveness and assesses sporozoite integrity in oocysts.
Area of Science:
- Parasitology
- Microbiology
- Diagnostic techniques
Background:
- Modified Ziehl-Neelsen (ZN) acid-fast stain is the standard for Cryptosporidium oocyst detection in feces.
- Limited sensitivity of ZN staining for Cryptosporidium oocysts has been observed.
Purpose of the Study:
- To enhance the sensitivity of acid-fast staining for Cryptosporidium oocyst detection.
- To evaluate the effect of chemical treatments on oocyst preservation and staining.
- To assess the utility of propidium iodide staining for visualizing sporozoites and evaluating oocyst integrity.
Main Methods:
- Purification of Cryptosporidium oocysts from preserved fecal samples.
- Staining with modified Ziehl-Neelsen (ZN) and propidium iodide.
- Treatment of oocysts with 10% formalin and 0.5% sodium hypochlorite.
- Flow cytometric analysis of oocyst DNA content.
Main Results:
- Standard ZN staining showed low oocyst positivity (3-5%) with intact sporozoites absent.
- Formalin and sodium hypochlorite treatments significantly increased the percentage of acid-fast stained oocysts.
- Sodium hypochlorite treatment altered intra-oocyst sporozoites, as shown by flow cytometry.
- Propidium iodide staining effectively visualized sporozoites and assessed oocyst preservation.
Conclusions:
- Chemical treatments, particularly sodium hypochlorite, enhance the sensitivity of acid-fast staining for Cryptosporidium oocysts.
- Propidium iodide staining is a valuable tool for assessing sporozoite viability and oocyst integrity post-treatment.
- Optimized staining protocols can improve the diagnostic accuracy of Cryptosporidium detection.
