Background
Methods
Pneumococcal isolates
PCR identification of 6A, 6B-I, 6B-II, 6C, 6D, “6E”, “6F”, and “6G”
Antimicrobial susceptibility
Molecular epidemiology of serogroup 6 strains
Statistical analysis
Results
Serotype/subtype distributions and antibiotic susceptibility
MLST
Types | No. | ST982 | CC90 | CC4542 | CC4536 | CC2754 | ST2912 | CC8616 | CC386 | Others |
---|---|---|---|---|---|---|---|---|---|---|
6A | 105 | 47(44.8%) | 0 | 3(2.9%) | 14(13.3%) | 6(5.7%) | 2(1.9%) | 9(8.6%) | 0 | 24(22.9%) |
6B-I | 44 | 0 | 0 | 20(46.5%) | 1(2.3%) | 9(20.9%) | 0 | 1(2.3%) | 0 | 12(27.9%) |
6B-II | 58 | 0 | 41(69.5%) | 1(1.7%) | 0 | 0 | 0 | 0 | 10(16.9%) | 7(11.9%) |
6C | 14 | 1(7.1%) | 0 | 1(7.1%) | 0 | 0 | 9(64.3%) | 0 | 0 | 3(21.4%) |
6D | 4 | 4(100%) | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 |
Total | 225 | 52(23.1%) | 41(18.2%) | 25(11.1%) | 15(6.7%) | 15(6.7%) | 11(4.9%) | 10(4.4%) | 10(4.4%) | 46(20.4%) |
Associations between STs/CCs and antimicrobial resistance
CCs/STs | No. isolates | Oral penicillin breakpoints | MIC50 (μg/mL) | MIC90 (μg/mL) | MIC range (μg/mL) | |
---|---|---|---|---|---|---|
I | R | |||||
ST982 | 52 | 0 | 0 | 0.032 | 0.049 | 0.001–0.064 |
CC90 | 41 | 36(87.8%) | 5(12.2%) | 1 | 1.5 | 0.25–2 |
CC4542 | 25 | 0 | 0 | 0.016 | 0.023 | 0.003–0.032 |
ST2912 | 11 | 0 | 0 | 0.032 | 0.049 | 0.016–0.049 |
CC4536 | 15 | 0 | 0 | 0.016 | 0.032 | 0.016–0.064 |
CC2754 | 11 | 0 | 0 | 0.023 | 0.032 | 0.008–0.064 |
CC8616 | 10 | 0 | 0 | 0.016 | 0.023 | 0.002–0.023 |
CC386 | 10 | 4(40.0%) | 0 | 0.064 | 0.125 | 0.032–0.125 |
Others | 46 | 22(47.8%) | 4(8.7%) | 0.19 | 0.75 | 0.008–2 |
Total | 225 | 63(28.0%) | 9(4%) | 0.032 | 1 | 0.001–2 |
CC/STs | No. | CXMa
| IPMa* | ERYa* | CHLa* | TCYa
| SXTa
| MDRa(%) | |||
---|---|---|---|---|---|---|---|---|---|---|---|
I% | R% | I% | R% | R% | I% | R% | I% | R% | |||
ST982 | 52 | 0 | 0 | 0 | 98.1 | 3.8 | 1.9 | 98.1 | 1.9 | 98.1 | 98.1 |
CC90 | 41 | 4.9 | 87.8 | 19.5 | 100 | 58.5 | 0 | 95.1 | 4.9 | 92.7 | 100 |
CC4542 | 25 | 0 | 0 | 8.0 | 96.0 | 8.0 | 0 | 100 | 4.0 | 88.0 | 92.0 |
ST2912 | 11 | 0 | 0 | 0 | 100 | 0 | 36.4 | 45.5 | 9.1 | 63.6 | 63.6 |
CC4536 | 15 | 6.7 | 0 | 0 | 66.7 | 46.7 | 0 | 100 | 20.0 | 46.7 | 73.3 |
CC2754 | 15 | 0 | 6.7 | 0 | 100 | 6.7 | 0 | 93.3 | 13.3 | 86.7 | 93.3 |
CC8616 | 10 | 0 | 0 | 10.0 | 90.0 | 10.0 | 0 | 90.0 | 0 | 90.0 | 90.0 |
CC386 | 10 | 0 | 0 | 0 | 100 | 0 | 10.0 | 80.0 | 0 | 10.0 | 40.0 |
Others | 46 | 6.5 | 39.1 | 8.7 | 93.5 | 26.1 | 4.3 | 80.4 | 15.2 | 63.0 | 91.3 |
Total | 225 | 2.7 | 24.4 | 6.7 | 95.1 | 21.8 | 3.6 | 90.2 | 7.6 | 78.7 | 89.8 |
Years | No. | Serotypes/subtypes | CCs/STs | ||||||
---|---|---|---|---|---|---|---|---|---|
6A | 6B-I | 6B-II | CC90 | CC386 | CC855 | CC3173 | Singletons* | ||
2000-2002 | 39 | 4(10.3%) | 3(7.7%) | 32(82.1%) | 27(69.2%) | 3(7.7%) | 2(5.1%) | 0(0.0%) | ST76 (3), ST473,ST802, ST902, ST4545 |
2003-2005 | 9 | 2(22.2%) | 0(0.0%) | 7(77.8%) | 6(66.7%) | 0(0.0%) | 0(0.0%) | 1(11.1%) | ST282,ST8742 |
2006-2008 | 12 | 3(25.0%) | 2(16.7%) | 7(58.3%) | 6(50.0%) | 0(0.0%) | 2(16.7) | 2(16.7%) | ST135 |
2009-2011 | 12 | 6(50.0%) | 1(8.3%) | 5(41.7%) | 2(16.7%) | 1(8.3%) | 2(16.7%) | 5(41.7%) | ST135,ST2766 |
Total | 71 | 15(21.1%) | 6(8.5%) | 51(71.8%) | 41(57.7%) | 4(5.6%) | 6(8.5%) | 8(11.3%) |