TABLE 2.

Pneumococcal strains used in this study

Strain	Descriptiona	Reference or source
TIGR4	Invasive clinical isolate, capsular serotype 4, sensitive to antibiotics	85
D39	Avery strain, clinical isolate, capsular serotype 2; sensitive to antibiotics	87
R6	D39-derivative unencapsulated laboratory strain, sensitive to antibiotics	87
R6ΔspxBΔlctO	R6-derivative, hydrogen peroxide and autolysis deficient strain.	88
R6ΔlytAΔlytC	R6-derivative, autolysis deficient strain	89
EF3030	Clinical isolate, capsular serotype 19F, sensitive to antibiotics	50, 90
S. pneumoniae ATCC 49619	Invasive reference strain, recommended by the CLSIb for antimicrobial-sensitive test serotype 19F	American Type Culture Collection, 43
GA44288	Clinical isolate, capsular serotype 19A; ERY, TET, AMX, CXM, CLI, SXT, MEM, PEN, CRO, CTX	91
GA47281	Clinical isolate, capsular serotype 19F; ERY, TET, AMX, CXM, CLI, SXT, MEM, PEN, CRO, CTX	91
GA16833	Clinical isolate, capsular serotype 19F; ERY, TET, CXM	91
GA17227	Clinical isolate, capsular serotype 23F; ERY, TET	91

^aResistance to amoxicillin (AMX), cefuroxime (CXM), ceftriaxone (CRO), cefotaxime (CTX), clindamycin (CLI), erythromycin (ERY), meropenem (MEM), penicillin (PEN), tetracycline (TET), trimethoprim-sulfamethoxazole (SXT).

^bCLSI, Clinical and Laboratory Standards Institute.