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Volume 31, Supplement—April 2025
SUPPLEMENT ISSUE
Supplement
Successful Transition to Whole-Genome Sequencing and Bioinformatics to Identify Invasive Streptococcus spp. Drug Resistance, Alaska, USA
Karen M. Miernyk
, Sopio Chochua, Ben Metcalf, Alisa Reasonover, and Brenna Simons-Petrusa
, Sopio Chochua, Ben Metcalf, Alisa Reasonover, and Brenna Simons-Petrusa
Table 2
Discordance between phenotypic testing and whole-genome sequence predictions along with resistance determinants for Streptococcus spp. in study to identify invasive Streptococcus spp. drug resistance, Alaska, USA, 1986–2021*
| Organism resistance mechanism | Antimicrobial drug | WGS predicted MIC, μg/mL | Initial phenotypic MIC, μg/mL | Follow-up testing for >2 dilution discrepancy |
||
|---|---|---|---|---|---|---|
| MIC, μg/mL | Agrees with WGS, no. | True discrepancy, no. | ||||
| Streptococcus agalactiae | ||||||
| lsaC gene | Clindamycin | >1, R | 0.25, S | 0.25, S | 0 | 1 |
| negative |
Clindamycin | <0.25, S | 2, R | 0.064, S | 1 | 0 |
| Clindamycin | <0.25, S | 2, R | 0.047, S | 1 | 0 | |
| Erythromycin | <0.25, S | 0.5, I | 0.047, S | 1 | 0 | |
| Erythromycin |
<0.25, S |
8, R |
0.064, S |
1 |
0 |
|
| S. pyogenes | ||||||
| ermTR gene | Clindamycin† | >1, R | <0.12, S | All D-Zone + | 8 | 0 |
| Negative |
Tetracycline | <2, S | 4, I | 0.125, S | 1 | 0 |
| Erythromycin |
<0.25, S |
2, R |
0.064, S |
1 |
0 |
|
| S. pneumoniae | ||||||
| mef gene | Erythromycin | 8, R | 0.12, S | 4, R | 1 | 0 |
| negative | Chloramphenicol | <2, S | 8, R | 2, S | 1 | 0 |
| Levofloxacin | <2, S | 4, I | 0.5, S | 1 | 0 | |
| Erythromycin | 0.06, S | 1, R | 0.06, S | 1 | 0 | |
| Tetracycline | <0.25, S | 4, I | 0.125, S | 1 | 0 | |
| Tetracycline | <0.25, S | >16, R | 0.25, S | 1 | 0 | |
| Tetracycline | <0.25, S | >16, R | 0.125, S | 1 | 0 | |
| Quinupristin, dalfopristin | <1, S | >4, R | Sensitive‡ | 13 | 0 | |
| Rifampin | <1, S | >4, R | <0.064, S | 24 | 0 | |
*I, intermediate resistance; R, resistant; S, susceptible; WGS, whole-genome sequencing; +, positive. †Follow-up testing for clindamycin used BD BBL Sensi-Disc for the D-Zone test (BD, https://www.bd.com). ‡Determined by disk diffusion.
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Page updated: April 14, 2025
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