Profiling of volatile organic compounds in clinical isolate cultures and stools from children withClostridioides difficileinfection by HS-SPME-GC-MS.

Bacterial volatile organic compounds (VOCs) have been investigated as a non-invasive approach to diagnosis of infectious diseases. Here, we aimed to explore potential diagnostic markers by profiling VOCs in cultures of unique clinicalClostridioides difficileisolates and stool samples from pediatric patients withC. difficileinfection (CDI) using headspace solid-phase microextraction coupled with gas chromatography combined with mass spectrometry (HS-SPME-GC-MS). A total of 106 individual compounds were detected in 39C. difficileisolate cultures, of which 1-hexanol, ethanol and 4-methylvaleric acid were detected in all bacterial cultures, and 2-methyl-butanoic acid, 1-pentanol, 2-methyl-1-propanol,p-xylene and 6-methyl-2-heptanone were found in 38 (97.4%), 37 (94.9%), 34 (87.2%), 34 (87.2%) and 32 (82.1%) isolate cultures, respectively. The most abundant compound was 4-methylvaleric acid (relative abundance 14.71%, interquartile range 11.73%, 16.38%). A direct comparison of six paired isolates and stools revealed the transfer ofC. difficileisolate VOCs to feces: ethanol was detected in all six pairs, 4-methylvaleric acid was in five pairs and 1-hexanol in four pairs. Fecal VOC patterns between the CDI children and healthy children were significantly different. Receiver operating characteristic analysis showed that 1-propanol, 6-methyl-2-heptanone, phenylethyl alcohol and ethanol presented the highest discrimination value for differentiating feces of CDI children from healthy children. Our data indicate that fecal 1-propanol, 6-methyl-2-heptanone, phenylethyl alcohol and ethanol may be used as potential screening biomarkers for diagnosing CDI.