Volume 19, Number 7—July 2013
Research
Pneumococcal Serotypes before and after Introduction of Conjugate Vaccines, United States, 1999–20111
, Kristopher P. Heilmann, Cassie L. Dohrn, Fathollah Riahi, Daniel J. Diekema, and Gary V. Doern
Table 1
Patient demographics and penicillin susceptibility for Streptococcus pneumoniae isolates, United States, 1999–2011*
| Characteristic | No. (%) isolates |
|||
|---|---|---|---|---|
| Before PCV7, 1999–2000, n = 1,506 | Post-PCV7, 2004–2005, n = 1,647 | Post-PCV7, 2008–2009, n = 1,946 | Post-PCV13, 2010–2011, n = 1,750 | |
| Medical center location | ||||
| Northeast | 390 (26) | 470 (29) | 495 (25) | 395 (23) |
| Midwest | 394 (26) | 403 (24) | 395 (20) | 433 (25) |
| Southeast | 224 (15) | 281 (17) | 343 (18) | 340 (19) |
| Southwest | 300 (20) | 265 (16) | 414 (21) | 396 (23) |
| West |
198 (13) |
228 (14) |
299 (15) |
186 (11) |
| Patient location | ||||
| Inpatient | 846 (56) | 995 (60) | 1,056 (54) | 987 (56) |
| Outpatient | 654 (43) | 624 (38) | 817 (42) | 734 (42) |
| Unknown |
6 (0.4) |
28 (2) |
73 (4) |
29 (2) |
| Age, y | ||||
| 0–5† | 442 (29) | 328 (20) | 417 (21) | 367 (21) |
| 6–20 | 86 (6) | 137 (8) | 160 (8) | 173 (10) |
| 21–64 | 627 (42) | 769 (47) | 861 (44) | 824 (47) |
| ≥65 | 336 (22) | 350 (21) | 425 (22) | 376 (21) |
| Unknown |
15 (1) |
63 (4) |
83 (4) |
10 (0.6) |
| Specimen source | ||||
| Blood‡ | 460 (31) | 406 (25) | 454 (23) | 428 (24) |
| Cerebrospinal fluid | 20 (1) | 14 (1) | 19 (1) | 16 (1) |
| Other sterile body fluid | –§ | 16 (1) | 31 (2) | –§ |
| Middle ear fluid | 125 (8) | 126 (8) | 118 (6) | 110 (6) |
| Lower respiratory tract | 670 (44) | 870 (53) | 953 (49) | 840 (48) |
| Sinus | 44 (3) | 91 (6) | 144 (7) | 147 (8) |
| Other |
187 (12) |
124 (8) |
227 (12) |
209 (12) |
| Penicillin (all isolates) | ||||
| Susceptible (MIC ≤0.06 µg/mL)¶ | 1,005 (67) | 1,112 (68) | 1,213 (62) | 1,066 (61) |
| Intermediate (MIC 0.12–1 µg/mL)# | 178 (12) | 295 (18) | 403 (21) | 352 (20) |
| Resistant (MIC ≥2 µg/mL)** |
323 (21) |
240 (15) |
330 (17) |
332 (19) |
| Penicillin (noninvasive isolates, oral breakpoint) | ||||
| Susceptible (MIC ≤0.06 µg/mL) | 652 (64) | 793 (65) | 828 (57) | 747 (57) |
| Intermediate (MIC 0.12–1 µg/mL) | 127 (12) | 221 (18) | 329 (23) | 279 (21) |
| Resistant (MIC ≥2 µg/mL) |
247 (24) |
197 (16) |
285 (20) |
280 (21) |
| Penicillin (all invasive isolates, meningitis parenteral breakpoint) | ||||
| Susceptible (MIC ≤0.06 µg/mL) | 353 (74) | 319 (73) | 385 (76) | 319 (72) |
| Resistant (MIC ≥0.12 µg/mL) |
127 (26) |
117 (27) |
119 (24) |
125 (28) |
| Penicillin (invasive isolates, CSF excluded, nonmeningitis parenteral breakpoint) | ||||
| Susceptible (MIC ≤2 µg/mL) | 442 (96) | 400 (95) | 458 (94) | 392 (92) |
| Intermediate (MIC 4 µg/mL) | 18 (4) | 22 (5) | 26 (5) | 35 (8) |
| Resistant (MIC ≥8 µg/mL) | 0 | 0 | 1 (0.2) | 1 (0.2) |
*PCV7, pneumococcal conjugate 7-valent vaccine; PCV13, pneumococcal conjugate 13-valent vaccine.
†Significant decrease from 29% in the preconjugate vaccine period to 20%–21% in the postconjugate vaccine period (p<0.001).
‡Significant decrease from 31% in 1999–2000 to 23%–25% in the postconjugate vaccine period (p<0.01).
§Other sterile body fluids were not recorded as a separate specimen source category during these 2 periods.
¶Penicillin susceptible: parenteral therapy for meningitis or oral therapy.
#Penicillin intermediate: oral therapy, resistant if parenteral therapy for meningitis.
**Penicillin resistant: parenteral therapy for meningitis or oral therapy.
1Presented in part at the 112th General Meeting of the American Society for Microbiology Annual Meeting, June 19, 2012, San Francisco, CA, USA (abstract no. 2986).