Test Catalog

Test ID: PNTOR    
Streptococcus pneumoniae IgG Antibodies, Total, with Reflex, Serum

Useful For Suggests clinical disorders or settings where the test may be helpful

Assessing the IgG antibody response to active immunization with nonconjugated 23-valent vaccines


Assessing the IgG antibody response to active immunization with conjugated 13-valent and 7-valent vaccines


Determining the ability of an individual to produce an antibody response to polysaccharide antigens, as part of an evaluation for humoral or combined immunodeficiencies

Testing Algorithm Delineates situations when tests are added to the initial order. This includes reflex and additional tests.

If the result is 41.0 mcg/mL or greater and less than 181.0 mcg/mL, then Streptococcus pneumoniae IgG antibodies for 23 serotypes will be performed at an additional charge.

Clinical Information Discusses physiology, pathophysiology, and general clinical aspects, as they relate to a laboratory test

Streptococcus pneumoniae is a gram-positive bacterium that causes a variety of infectious diseases in children and adults. These include invasive disease (bacteremia and meningitis) and infections of the respiratory tract (pneumonia and otitis media). There is an annual estimated number of 5000 cases of pneumococcal bacteremia (without pneumonia) with a fatality rate of approximately 20%, reaching as high as 60% in the elderly population. It is estimated that as many as 400,000 hospitalizations from pneumococcal pneumonia occur annually in the United States, with a case-fatality rate of 5% to 7%.


More than 90 serotypes of S pneumoniae have been identified, based on varying polysaccharides that are found in the bacterial cell wall. The serotypes responsible for disease vary with age and geographic location.


Bacterial polysaccharides induce a T-cell independent type II humoral immune response. Vaccines containing bacterial polysaccharides can be effective in generating an immune response that results in production of IgG antibodies and generation of long-lived plasma and memory B cells, which can protect an individual against bacterial disease.


Active immunization is performed with a nonconjugated polysaccharide vaccine (Pneumovax) that contains a total of 23 serotypes, namely 1, 2, 3, 4, 5, 6B, 7F, 8, 9N, 9V, 10A, 11A, 12F, 14, 15B, 17F, 18C, 19A, 19F, 20, 22F, 23F, and 33F. These 23 serotypes were included because, as a group, they account for approximately 90% of invasive pneumococcal infections. This nonconjugated vaccine is indicated for all adults 65 years of age and older, individuals between 2 and 64 years with chronic diseases (heart disease, lung disease, type I diabetes, liver disease), those who are immunocompromised (congenital or acquired immunodeficiencies, malignancy, solid-organ transplant), those with functional or anatomic asplenia, and adults 19 to 64 years who smoke. Because not all patients can generate a robust T-cell independent antibody response, conjugated vaccines such as Prevnar (7-valent) and Prevnar 13 (13-valent) were developed, in which the polysaccharide is conjugated to the CRM197 protein and therefore initiates a T-cell dependent antibody response. Immunization with the conjugated vaccine is indicated in all children under 2 years old, all adults 65 years and older, and individuals with medical conditions such as immunodeficiency, chronic obstructive pulmonary disease, and congestive heart failure.


Antibody responses develop in approximately 75% to 85% of nonimmunocompromised adults and older children approximately 4 to 6 weeks following immunization.

Reference Values Describes reference intervals and additional information for interpretation of test results. May include intervals based on age and sex when appropriate. Intervals are Mayo-derived, unless otherwise designated. If an interpretive report is provided, the reference value field will state this.

> or =9.7 mcg/mL

Interpretation Provides information to assist in interpretation of the test results

Low antipneumococcal antibody concentrations (<9.7 mcg/mL) indicate a poor response to the pneumococcal vaccine, while high concentrations (>270.0 mcg/mL) indicate a robust vaccine response. Results falling in the modest (9.7-40.9 mcg/mL), intermediate (41.0-180.9 mcg/mL), and moderate (181.0-270.0 mcg/mL) categories may warrant serotype-specific antibody testing, to be determined at the discretion of the physician.


When comparing pre- and post-vaccination samples, an increase in antibody concentrations is generally considered to be indicative of a normal vaccine response. However, the specific fold increase is influenced substantially by the antibody concentration observed in the pre-vaccination sample.

Cautions Discusses conditions that may cause diagnostic confusion, including improper specimen collection and handling, inappropriate test selection, and interfering substances

Protective concentrations of IgG antibodies, or those required to prevent infection from Streptococcus pneumoniae, have not been defined.


Quantitation of the IgG antibody response to pneumococcal serotypes does not provide any information on their functional capacity (opsonization efficiency).

Clinical Reference Recommendations for in-depth reading of a clinical nature

1. Parker AR, Lock E, Iftikhar A, et al: Purification and characterization of anti-pneumococcal capsular polysaccharide IgG immunoglobulins. Clin Biochem. 2017 Jan;50(1-2):80-83

2. Parker AR, Park MA, Harding S, Abraham RS: The total IgM, IgA and IgG antibody responses to pneumococcal polysaccharide vaccination (Pneumovax23) in a healthy adult population and patients diagnosed with primary immunodeficiencies. Vaccine. 2019 Feb 28;37(10):1350-1355

3. Moffitt KL, Malley R: Next generation pneumococcal vaccines. Curr Opin Immunol. 2011 June;23(3):407-413

4. Paradiso PR: Advances in pneumococcal disease prevention: 13-valent pneumococcal conjugate vaccine for infants and children. Clin Infect Dis. 2011 May;52(10):1241-1247

5. Daly TM, Hill HR: Use and clinical interpretation of pneumococcal antibody measurements in the evaluation of humoral immune function. Clin Vaccine Immunol. 2015 Feb;22(2):148-152 

6. Reynolds MM, Murray DL, Willrich MAV, et al: Total vs antigen specific pneumococcal antibody response: A comparison of two different assay types. Clin Chem. 2015 Oct;61(10):S77