Paramecium, a protozoan that ingests nonnutritive particulate matter, was used to determine the mutagenicity of fly ash. Heat treatment inactivated mutagens that require metabolic conversion to their active form but did not destroy all mutagenicity. Extraction of particles with hydrochloric acid, but not dimethyl sulfoxide, removed detectable mutagenic activity.

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The use of the established mutagenesis assay in Paramecium as a prescreen for hazardous environmental particles is described. Since these protozoans ingest particles of the size respired by animals and man, the biological effects of the respirable fraction of fly ash particles were monitored in particle-feeding eukaryotic cells. Fly ash from coal combustion was utilized for these studies and was found to be mutagenic. The effects of physical and chemical treatment of the particle mutagenicity provided evidence for both heat-stable, heat-labile and acid extractable mutagenic agents.

Up to now, little has been known about the prevalence and clinical relevance of colonisation of asymptomatic pregnant women with methicillin-susceptible Staphylococcus aureus (MSSA), methicillin-resistant S. aureus (MRSA) or extended-spectrum β-lactamase (ESBL)-producing Escherichia coli. In this two-centre cross-sectional study, we evaluated the performance and importance of screening at different times and different locations for colonisation in pregnant women and newborns. Between October 2013 and December 2015, four samples were collected from pregnant women, two from newborns at birth and three from 3-day-old newborns. Samples were screened on culturing media and were confirmed with molecular methods. MSSA was used as a surrogate for MRSA, as the two share most microbiologic characteristics and colonisation patterns. Of 763 pregnant women, 14.5% (111) were colonised with MSSA, 0.4% (3) with MRSA and 2.6% (20) with ESBL-producing E. coli. Of 658 newborns, 0.9% (10) were colonised with MSSA at birth and 13.1% (70) at 3 days old, 0.5% (3) were colonised with MRSA and 2.6% (17) with ESBL-producing E. coli. Nasal sampling identified 91.0% of MSSA-colonised pregnant women and 60.0% of newborns. In newborns, nasal and umbilical sampling at 3 days after birth discovered 84.0% of colonised cases. For ESBL-producing E. coli, the perianal region was positive in all colonised pregnant women and in 88.2% of colonised newborns. Combining nasal and perianal swabs is optimal when screening for antibiotic-resistant bacteria in pregnant women. Nasal, perianal and umbilical sample collection from 3-day-old newborns significantly increased the sensitivity compared to screening immediately after birth.