Volume 23, Number 6—June 2017
Research
Invasive Serotype 35B Pneumococci Including an Expanding Serotype Switch Lineage, United States, 2015–2016
Table 2
Nonserotype 35B isolates of ST156 lineage included in study of penicillin-nonsusceptible 35B pneumococcal isolates causing IPD, United States, 1998–2015*
| Serotype/ MLST type (no.)† | No. | PBP type‡ | Non-PBP resistance determinants§ | Antimicrobial resistance phenotype, MIC, μg/mL¶ |
State (year isolated) | |||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Pen | Amo | Tax | Cft | Cfx | Mer | Ery | Cli + Tet | Cot | Fq | |||||
| 9V/156 (25) |
12 | 15:12:18 | folAI100L, folPins178 | 4 | 2 | 1 | 2 | >2 | 0.5 | S | S | R | S | CA, GA, MD, MN, NY, TN (1998–1999) |
| 9 | 15:12:18 | mef, folAI100, folPins178 | 4 | 2 | 1 | 2 | >2 | 0.5 | R | S | R | S | CA, CT, MD, MN, OR, TN (1998,1999, 2015) | |
| 2 | 15:12:18 | ermB, tetM, folAI100L, folAins178 | 4 | 2 | 1 | 2 | >2 | 0.5 | R | R | R | S | CA (2015) | |
| 1 | 15:12:18 | mef, tetM, folAI100L, folPins178 | 4 | 2 | 1 | 2 | >2 | 0.5 | R | S | R | S | CT (2015) | |
| 1 |
15:12:228 |
Mef, folAI100L, folPins178 |
4 |
2 |
1 |
2 |
>2 |
0.5 |
R |
S |
R |
S |
MD (2016) |
|
| 19A/156 (4) |
3 | 29:12:26 | mef, folAI100L, folAins189 | 4 | 2 | 8 | 4 | >2 | 0.5 | R | S | R | S | CA,GA (2009) |
| 1 |
8:12:36 |
mef, folAI100L, folAins189 |
1 |
2 |
0.5 |
0.5 |
2 |
0.25 |
R |
S |
R |
S |
GA (2015) |
|
| 13/156 (1) |
1 |
15:12:173 |
folAI100L, folPins178 |
1 |
1 |
0.25 |
0.25 |
1 |
0.5 |
S |
S |
R |
S |
TN (2015) |
| 31/156 (1) | 1 | 15:12:18 | mef, folAI100L, folPins178 | 4 | 2 | 1 | 2 | >2 | 0.5 | R | S | R | S | MN (2015) |
*All isolates were positive for pilus PI-type 1 and negative for pilus PI-type 2. IPD, invasive pneumococcal disease; MLST, multilocus sequence type; PBP, penicillin-binding protein; R, resistant; S, susceptible; ST, sequence type.
†Types that probably arose through serotype switching are indicated in bold.
‡See Li et al. (15) and MIC correlates for PBP types (http://www.cdc.gov/streplab/mic-tables.html).
§For a description of WGS-based bioinformatic pipeline for deduction of all features shown, see Metcalf et al. (6,12). For a description of folP insertions (folPins178, folP189), see Figure 1 in Metcalf et al. (12).
¶Predicted MICs for β-lactam antimicrobial drugs were based on transpeptidase domain sequences of PBPs 1a, 2b, and 2x (http://www.cdc.gov/streplab/mic-tables.html). For penicillin (meningitis only), nonsusceptible is considered >0.12 μg/mL (16). Currently applied clinical cutoffs are also provided for the other 5 β-lactams shown (16). Where shown, R and S correspond to breakpoint MIC values (16). Amo, amoxicillin; Cft, ceftriaxone; Cfx, cefuroxime; Cli, clindamycin; Cot, cotrimoxazole; Ery, erythromycin; Fq, fluoroquinolones levofloxacin and ciprofloxacin; Mer, meropenem; Pen, penicillin; Tax, cefotaxime.