TABLE 5.
Summary of 10 amino acid mutations in the gyrA gene products of 26 (14 MDR, 7 XD, and 5 fully susceptible) M. tuberculosis isolates from South Africa deduced by Ion Torrent sequencing and culture
| No. of isolates | Amino acid substitution(s)a yielded by the gyrA gene (2,664 bp) | Fluoroquinolone result by: |
|
|---|---|---|---|
| Ion Torrentb | Bactec MGIT 960 | ||
| 3 | E21Q, S95T, G247S, G668D | Sensitive | Sensitive |
| 2 | E21Q, D94G, S95T, G668D | Resistant | Resistant |
| 1 | E21Q, G88C, S95T, G688D | Resistant | Resistant |
| 10 | E21Q, S95T, G668D | Sensitive | Sensitive |
| 1 | Wild typea | Sensitive | Sensitive |
| 1 | E21Q, S95T, G668D, Q613Q/Ec | Sensitive | Sensitive |
| 1 | E21Q, S95T, G668D, L549S/Lc | Sensitive | Sensitive |
| 1 | E21Q, D94Y, S95T, G668D | Resistant | Resistant |
| 6 | E21Q, A90V, S95T, G247S, G668D | Resistant | Resistant |
a
Compared to the H37Rv reference strain.
b
Fluoroquinolone resistance is known to occur in the gyrA gene product at positions 88 (G→C), 90 (A→V), 91 (S→P), and 94 (D→H) (indicated in bold).
c
There is a heterozygous nucleotide mutation in a proportion of Ion Torrent reads; the mutation confers a mixed amino acid substitution.