Reference Raman Spectrum and Mapping of Cryptosporidium parvum Oocysts

Abstract

Cryptosporidium parvum is a protozoan parasite and among the most infectious diarrhea-causing pathogens, leading to severe health problems for malnourished children and immunocompromised individuals. Outbreaks are common even in developed countries, originating from water or food contamination and resulting in suffering and large costs for society. Therefore, robust, fast and highly specific detection strategies of Cryptosporidium are needed. Label-free detection techniques such as Raman spectroscopy have been suggested, however high-resolution reported spectra in the literature are limited. In this work, we report reference Raman spectra at 3 cm^{-1} resolution for viable and inactivated Cryptosporidium oocysts of the species C. parvum, gathered at a single oocyst level using a laser tweezers Raman spectroscopy system. We furthermore provide tentative Raman peak assignments for the Cryptosporidium oocysts, along with Raman mapping of the oocysts' heterogeneous internal structure. Finally, we compare the C. parvum Raman spectrum with other common enterotoxigenic pathogens: Escherichia coli, Vibrio cholerae, Bacillus cereus and Clostridium difficile. Our results show a significant difference between C. parvum Raman spectra and the other pathogens.

Reactive oxygen species generated by infrared laser light in optical tweezers inhibits the germination of bacterial spores

“…Optical tweezers have been used extensively to characterize and assess spore mechanisms on an individual level [9, 20–26], but the number of studies detailing the impact laser trapping has on the spore is limited. In a recent work, it was shown that optical tweezers could cause structural changes at high dose levels.…”