Validation of Factor 6d Antiserum for Serotyping
            <i>Streptococcus pneumoniae</i>
            Serotype 6C

Jacobs, Michael; Dagan, Ron; Bajaksouzian, Saralee; Windau, Anne; Porat, Nurith

doi:10.1128/jcm.01907-09

Cited by 14 publications

(18 citation statements)

References 15 publications

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“…tute (SSI) has also recently produced factor 6d against serotype 6C (5). Our DF-6b, unlike the SSI factor 6b, is now serotype 6A specific and does not cross-react against serotype 6C.…”

mentioning

confidence: 98%

Serotype-Specific Typing Antisera for Pneumococcal Serogroup 6 Serotypes 6A, 6B, and 6C

2010

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ᰔStreptococcus pneumoniae strains can express one of at least 92 capsular serotypes. To our knowledge, our laboratory is one of two that maintain antisera for resolution of the first 90 discovered pneumococcal serotypes (4; unpublished data). Recently, the evaluation of serogroup 6 isolates using monoclonal antibodies led to the discovery of the 91st serotype, 6C (7), which has become the prevalent invasive serogroup 6 serotype within the United States (2, 9). The pneumococcal 7-valent conjugate vaccine (PCV7) does not protect against it, and it is not included within the newly licensed 13-valent conjugate vaccine. In addition, serotype 6C carriage may also be common within PCV7-vaccinated populations (3). Prior to the discovery of serotype 6C, serotypes 6A and 6B were the 2 known serogroup 6 serotypes. CDC antisera for quellung-based resolution of serotypes 6A and 6B are designated as Danish factors 6b and 6c (DF-6b and DF-6c), respectively. Our original DF-6b antiserum was positive for both 6A and 6C serotypes, preventing their resolution (Table 1).We produced DF-6d antiserum specific to serotype 6C and DF-6b antiserum specific to 6A as follows. New Zealand White female rabbits were inoculated with S. pneumoniae serotypes 6C or 6A formalin-fixed whole cells. The inocula consisted of serotype 6C or 6A cell suspensions (10 8 to 10 9 cells per ml in phosphate-buffered saline), which were administered intravenously via the marginal ear vein (Table 2). Blood was drawn after week 4 of dosing, and serum was evaluated for antibody titer to serotype 6C or 6A and cross-reactivity to serotypes 6A, 6B, and 6C by the quellung reaction. Cross-reactivity was removed from DF-6d by absorbing the serum with formalin-fixed cells of serotypes 6A and 6B. DF-6b antiserum was absorbed with formalin-fixed cells of serotypes 6B and 6C. The resulting DF-6d antiserum was specific for serotype 6C only, and DF-6b was specific to 6A only (Table 1).The specificity of DF-6b, DF-6c, and DF-6d antisera was evaluated with stock strains and 159 clinical isolates, each representing one of the serotypes 6A, 6B, or 6C. For all strains, Neufeld quellung results were compared to PCR testing specific for the serotype 6C wicN 6C locus (2,7,8) with no inconsistencies observed.We have replaced our previous methods with these procedures for producing specific factor sera against serotypes 6A and 6C. We have now learned that Statens Serum Institute (SSI) has also recently produced factor 6d against serotype 6C (5). Our DF-6b, unlike the SSI factor 6b, is now serotype 6A specific and does not cross-react against serotype 6C.Serotype 6C-specific antiserum will be useful for laboratories which utilize quellung testing. Recently a fourth serogroup 6 serotype, serotype 6D, has been discovered in nature (1,6)

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“…tute (SSI) has also recently produced factor 6d against serotype 6C (5). Our DF-6b, unlike the SSI factor 6b, is now serotype 6A specific and does not cross-react against serotype 6C.…”

mentioning

confidence: 98%

Serotype-Specific Typing Antisera for Pneumococcal Serogroup 6 Serotypes 6A, 6B, and 6C

2010

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“…ᰔ A recent study by Jacobs et al (3) examined the specificity of a newly introduced pneumococcal capsule-specific antiserum (factor serum 6d) manufactured by Statens Serum Institut (SSI) in Denmark. The factor serum 6d was designed to be specific for serotype 6C, a newly described pneumococcal serotype (5), and was to complement factor sera 6b and 6c, which are designed to be specific for pneumococcal serotypes 6A and 6B, respectively.…”

Section: Cross-reactivity Of Current Serogroup 6 Factor Sera From Stamentioning

confidence: 99%

Cross-Reactivity of Current Serogroup 6 Factor Sera from Statens Serum Institut with the Recently Described Pneumococcal Serotype 6D

Bratcher

Nahm

2010

J Clin Microbiol

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“…DNA of isolates previously described as 6A was used in a multiplex PCR developed by Jacobs et al to distinguish between serotypes 6A, B, and C (12 (13).…”

Section: Patients and Isolatesmentioning

confidence: 99%

“…As a result, a galactose of the serotype 6A capsular polysaccharide is substituted for a glucose in serotype 6C. Serotype 6C cross-reacts serologically with the 6A antiserum by the Quellung reaction; 6C-specific antiserum (factor antiserum 6d) was recently introduced to identify the 6C serotype (11,13).…”

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confidence: 99%

Increase in Prevalence of Streptococcus pneumoniae Serotype 6C at Eight Children's Hospitals in the United States from 1993 to 2009

et al. 2011

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Streptococcus pneumoniae serotype 6C, which was described in 2007, causes invasive disease in adults and children. We investigated the prevalence of 6C among pediatric isolates obtained from eight children's hospitals in the United States. S. pneumoniae isolates were identified from a prospective multicenter study (1993 to 2009). Fifty-seven serotype 6C isolates were identified by multiplex PCR and/or Quellung reaction. Five were isolated before 2000, and the prevalence increased over time (P < 0.000001). The median patient age was 2.1 years (range, 0.2 to 22.5 years). Clinical presentations included bacteremia (n ‫؍‬ 24), meningitis (n ‫؍‬ 7), pneumonia (n ‫؍‬ 4), abscess/wound (n ‫؍‬ 3), mastoiditis (n ‫؍‬ 2), cellulitis (n ‫؍‬ 2), peritonitis (n ‫؍‬ 1), septic arthritis (n ‫؍‬ 1), otitis media (n ‫؍‬ 10), and sinusitis (n ‫؍‬ 3). By broth microdilution, 43/44 invasive serotype 6C isolates were susceptible to penicillin (median MIC, 0.015 g/ml; range, 0.008 to 2 g/ml); all were susceptible to ceftriaxone (median MIC, 0.015 g/ml; range, 0.008 to 1 g/ml). By disk diffusion, 16/44 invasive isolates (36%) were nonsusceptible to erythromycin, 19 isolates (43%) were nonsusceptible to trimethoprimsulfamethoxazole (TMP-SMX), and all isolates were clindamycin susceptible. Multilocus sequence typing (MLST) revealed 24 sequence types (STs); 9 were new to the MLST database. The two main clonal clusters (CCs) were ST473 and single-locus variants (SLVs) (n ‫؍‬ 13) and ST1292 and SLVs (n ‫؍‬ 23). ST1292 and SLVs had decreased antibiotic susceptibility. Serotype 6C causes disease in children in the United States. Emerging CC1292 expressed TMP-SMX resistance and decreased susceptibility to penicillin and ceftriaxone. Continued surveillance is needed to monitor changes in serotype prevalence and possible emergence of antibiotic resistance in pediatric pneumococcal disease.

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Validation of Factor 6d Antiserum for Serotyping Streptococcus pneumoniae Serotype 6C

Cited by 14 publications

References 15 publications

Serotype-Specific Typing Antisera for Pneumococcal Serogroup 6 Serotypes 6A, 6B, and 6C

Serotype-Specific Typing Antisera for Pneumococcal Serogroup 6 Serotypes 6A, 6B, and 6C

Cross-Reactivity of Current Serogroup 6 Factor Sera from Statens Serum Institut with the Recently Described Pneumococcal Serotype 6D

Increase in Prevalence of Streptococcus pneumoniae Serotype 6C at Eight Children's Hospitals in the United States from 1993 to 2009

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