We evaluated the results from patients that had their stool samples tested by whole genome enrichment NGS, and their nasopharyngeal swabs tested by RT-PCR for the presence of SARS-CoV-2. Of the 14 study participants, ten were symptomatic and tested positive for SARS-CoV-2 by RT-PCR, two asymptomatic individuals tested negative, and two other asymptomatic individuals did not undergo RT-PCR testing (Table 1). Patients 5 and 7, that tested positive by RT-PCR from nasopharyngeal swabs, were treated with Hydroxychloroquine (HCQ), Azithromycin, vitamin C, vitamin D, and zinc for 10 days prior to fecal collection. Similarly, after positive nasopharyngeal swab, patient 13 was treated with vitamin C, vitamin D, and zinc for 10 days before fecal collection. The concordance of SARS-CoV-2 detection by enrichment NGS from stools among positive non-treated patients tested by RT-PCR nasopharyngeal analysis was 100% (7/7). Patient 8, who did not undergo nasopharyngeal analysis, tested positive for SARS-CoV-2 by NGS. The three patients (5, 7, 13) that received treatment prior to providing fecal samples, all tested negative by NGS. Asymptomatic patients 2 and 9, who tested negative by nasopharyngeal swab, were also negative by NGS, as was asymptomatic patient 14.
Table 1
Symptoms and SARS-CoV-2 testing results
Sample ID | Symptoms | Nasopharyngeal Swab (RT-PCR) | Treated | Fecal (NGS) | Patient Location |
Patient 1 | febrile, diarrhea, anosmia, O2 sat. <90% | + | no | + | PA |
Patient 3 | febrile, diarrhea, O2 sat. <90% | + | no | + | CA |
Patient 4 | febrile, diarrhea, anosmia, O2 sat. <90% | + | no | + | AZ |
Patient 6 | febrile, cough, anosmia | + | no | + | AZ |
Patient 8 | none | n/a | no | + | CA |
Patient 10 | febrile, cough, headache | + | no | + | GA |
Patient 11 | febrile, cough, headache | + | no | + | GA |
Patient 12 | febrile, cough | + | no | + | GA |
Patient 5 | febrile, cough | + | yes | ─ | CA |
Patient 7 | febrile, cough | + | yes | ─ | GA |
Patient 13 | febrile, cough | + | yes | ─ | GA |
Patient 2 | none | ─ | no | ─ | CA |
Patient 9 | none | ─ | no | ─ | CA |
Patient 14 | none | n/a | no | ─ | CA |
All fecal samples analyzed by enrichment NGS from positive patients by RT-PCR, achieved 100% genome coverage of SARS-CoV-2 except for patient 3 which had 45%, and patient 10 which had 93% coverage (Table 2). The total number of SARS-CoV-2 mapped reads for patients 1, 3, 4, 6, 8, 10, 11, and 12 were 465645, 5984, 131582, 793603, 496852, 5929, 1270734, and 38256 respectively. The mean read depths of SARS-CoV-2 for patients 1, 3, 4, 6, 8, 10, 11, and 12 were 1129.8x, 31.7x, 318.6x, 1924.6x, 1206.7x, 15.5x, 3075.3x, and 92.7x respectively. The read depths at specific coordinates along the SARS-CoV-2 genome for each patient are captured in Fig. 1.
Table 2
Sample ID | Genome Coverage | Number of Variants | Mapped Reads | Mean Depth |
Patient 1 | 100% | 11 | 465645 | 1129.8x |
Patient 3 | 45% | 11 | 5984 | 31.7x |
Patient 4 | 100% | 9 | 131582 | 318.6x |
Patient 6 | 100% | 10 | 793603 | 1924.6x |
Patient 8 | 100% | 10 | 496852 | 1206.7 |
Patient 10 | 93% | 9 | 5929 | 15.6x |
Patient 11 | 100% | 10 | 1270734 | 3075.3x |
Patient 12 | 100% | 10 | 38256 | 92.7x |
Following alignment and mapping of SARS-CoV-2, patient genomes were compared to the Wuhan-Hu-1 (MN90847.3) SARS-CoV-2 reference genome via One Codex’s bioinformatics pipeline to identify mutational variations. This analysis identified nucleotide variants at positions nt241 (C → T) and nt23403 (A → G) across all positive patients, and variants at positions nt3037 (C → T) and nt25563 (G → T) in seven of the eight patients (Table 3). Interestingly, patients 8, 11, and 12 harbored the same set of variants, as did patients 4 and 6 (who were kindreds). Unique variants not identified in any of the other individuals were detected in patients 1, 3, 6, and 10, with patient 3 harboring the most distinct SARS-CoV-2 genome with eight unique variants, followed by patient 1 with seven. Collectively, there were thirty-three different mutations among the patients in which SARS-CoV-2 was detected by whole genome enrichment NGS.
Table 3
SARS-CoV-2 genomic positions, variant changes, and frequencies across the positive patient cohort
Region (ORF) | Position | Variant | Patient 1 | Patient 3 | Patient 4 | Patient 6 | Patient 8 | Patient 10 | Patient 11 | Patient 12 |
5’-UTR | 241 | C → T | 100% | 100% | 100% | 100% | 100% | 100% | 100% | 100% |
1a | 833 | T → C | x | x | x | x | 100% | x | 100% | 100% |
1a | 1059 | C → T | x | x | 100% | 100% | 99% | 100% | 100% | 100% |
1a | 1758 | C → T | x | x | 100% | 100% | x | x | x | x |
1a | 1973 | C → T | x | x | x | 87% | x | x | x | x |
1a | 3037 | C → T | 100% | x | 100% | 100% | 100% | 100% | 100% | 100% |
1a | 3078 | C → T | x | 89% | x | x | x | x | x | x |
1a | 4866 | G → T | 75% | x | x | x | x | x | x | x |
1a | 6720 | C → T | 93% | x | x | x | x | x | x | x |
1a | 8102 | G → T | x | 100% | x | x | x | x | x | x |
1a | 9401 | T → C | x | x | x | x | x | 64% | x | x |
1a | 9403 | T → A | x | x | x | x | x | 64% | x | x |
1a | 10870 | G → T | x | x | 100% | 100% | x | x | x | x |
1a | 11123 | G → A | x | x | 100% | 100% | x | x | x | x |
1b | 14408 | C → T | 100% | x | 100% | 100% | 100% | x | 100% | 100% |
1b | 14877 | C → T | x | 100% | x | x | x | x | x | x |
1b | 16616 | C → T | x | x | x | x | 100% | x | 100% | 100% |
1b | 16848 | C → T | 100% | x | x | x | x | x | x | x |
1b | 18652 | C → A | x | x | x | x | x | 83% | x | x |
1b | 19989 | T → G | x | 100% | x | x | x | x | x | x |
Spike | 21576 | T → G | x | 83% | x | x | x | x | x | x |
Spike | 23264 | G → A | x | 75% | x | x | x | x | x | x |
Spike | 23403 | A → G | 100% | 100% | 100% | 100% | 100% | 100% | 100% | 100% |
Spike | 23603 | C → T | 82% | x | x | x | x | x | x | x |
3a | 25563 | G → T | x | 100% | 100% | 100% | 100% | 100% | 100% | 100% |
3a | 25976 | C → A | x | x | x | x | 100% | x | 100% | 100% |
8 | 27964 | C → T | x | x | x | x | 100% | x | 100% | 100% |
Nucleoprotein | 28881 | G → A | 100% | x | x | x | x | x | x | x |
Nucleoprotein | 28882 | G → A | 100% | x | x | x | x | x | x | x |
Nucleoprotein | 28883 | G → C | 100% | x | x | x | x | x | x | x |
Nucleoprotein | 28997 | C → T | x | 100% | x | x | x | x | x | x |
Nucleoprotein | 29019 | A → T | x | 100% | x | x | x | x | x | x |
Nucleoprotein | 29364 | C → G | x | x | x | x | x | 85% | x | x |