Serologic comparison of 35B/ST156 lineage strains with CDC
Quellung reagents for resolution of serogroup 35B invasive serotype pneumococci including an expanding serotype switch lineage, United States, 2015-2016 *
Quellung factor Strain 35b 29b 35c 42a 35a cps35B ([dagger]) - + + - + cps35B (wciG deletion) - + + - - ([double dagger]) * CDC, Centers for Disease Control and Prevention; ST, sequence type; -, negative; +, positive.
Serotyping based on the
Quellung reaction requires expensive reagents and substantial training and experience to perform reliably.
Identification of capsular type by the
quellung reaction and resistance genotyping by real-time PCR was performed within 1 day of sample collection for each strain.
Serotyping was performed by use of the Neufeld
Quellung reaction, a technique previously described (22) by using polyclonal antisera.
Thirty strains were sent to CDC for serotyping but could not be typed using the
Quellung reaction.
Isolates received at the Spanish Reference Laboratory for Pneumococci were serotyped by using the
quellung reaction and antisera provided by the Staten Serum Institute (Copenhagen, Denmark) (8).
All pneumococci isolated in 1998 and 1999 were serotyped using the
quellung reaction.
Serotypes of all isolates were determined by the capsular
quellung reaction using antiserum purchased from the Statens Serum Institute (Copenhagen, Denmark).
Serogrouping and serotyping were performed by the
quellung reaction using antiserum provided by Statens Serum Institute (Copenhagen, Denmark) (8).
The capsular serotype of all isolates was determined by using the
Quellung reaction with antisera from the Statens Serum Institut (Copenhagen, Denmark).
All pneumococcal isolates that exhibited a positive
quellung reaction when commercial type-specific antiserum (Statens Serum Institute, Copenhagen, Denmark) was used were assigned a serotype (10).
