How should I interpret a positive urine pneumococcal antigen when my suspicion for pneumococcal disease is very low?

The popular urine pneumococcal antigen (UPA) (based on the C-polysaccharide of Streptococcus pneumoniae cell wall) has been a valuable diagnostic tool in diagnosing invasive pneumococcal infections, but may be associated with up to nearly 10% rate of false-positivity in hospitalized patients1.  Three factors have often been cited as the  cause of false-positive UPA results: a. Nasopharyngeal carriage; b.Prior invasive pneumococcal infection and;  c. Pneumococcal vaccination.

Among adults with nasopharyngeal carriage of S. pneumoniae, particularly those with HIV infection, 12-17% of positive UPA tests may be false-positive1. In patients with recent invasive pneumococcal disease, UAP may remain positive in over 50% of patient at 1 month and about 5% at 6 months1,2.

Among persons receiving the 23-valent polysaccharide pneumococcal vaccine (PPV), over 20% may have a positive UPA up to 30 hours following immunization, some potentially longer1.  In fact, the manufacturer of UPA assay recommends that UPA not be obtained within 5 days of receiving PPV. There is reason to believe that conjugated pneumococcal vaccine may be associated with the same phenomenon3.

So in a hospitalized patient with low suspicion for pneumococcal disease but a positive UAP, it would be wise to first exclude the possibility of PPV administration earlier during hospitalization before the sample was obtained1,4.

 

References

  1. Ryscavage PA, Noskin GA, Bobb A, et al. Incidence and impact of false-positive urine pneumococcal antigen testing in hospitalized patients. S Med J 2011;104:293-97.
  2. Andre F, Prat C, Ruiz-Manzano J, et al. Persistence of Streptococcus pneumoniae urinary antigen excretion after pneumococcal pneumonia. Eur J Clin Microbiol Infect Dis 2009;28:197-201.
  3. Navarro D, Garcia-Maset Leonor, Gimeno C, et al. Performance of the Binax NOW Streptococcus pneumoniae urinary assay for diagnosis of pneumonia in children with underlying pulmonary diseases in the absence of acute pneumococcal infection. J Clin Microbiol 2004; 42: 4853-55.
  4. Song JY, Eun BW, Nahm MH. Diagnosis of pneumococcal pneumonia: current pitfalls and the way forward. Infect Chemother 2013;45:351-66.

 

How should I interpret a positive urine pneumococcal antigen when my suspicion for pneumococcal disease is very low?

What’s the latest on vaccination of adults 65 years old or over with conjugated pneumococcal vaccine?

Since August, 2014, the Advisory Committee on Immunization Practices (ACIP) has recommended routine use of 13-valent pneumococcal conjugated vaccine (PCV13, Prevnar) in adults ≥ 65 years, in addition to the traditional 23-valent pneumococcal polysaccharide vaccine (PPSV23, Pneumovax) (1).   The approval of PCV13 was based on a large randomized, double-blind, placebo-controlled trial (CAPITA) that found PCV13 effective in preventing vaccine-type pneumococcal, bacteremic, and nonbacteremic community-acquired pneumonia and vaccine-type invasive pneumococcal disease (2).

Due to the potential  for mutual interference with immunogenecity, these 2 vaccines should be spaced apart. When PPSV23 is administered first, PCV13 should be held for 1 year or longer. On the other hand, when PCV13 is administered first, PPSV23 can be given within 6-12 months (minimum 8 weeks). So it makes sense to give PCV13 first in our older pneumococcal vaccine-naive patients.

 

1. Tomczyk S, Bennett NM, Stoecker C, et al. Use of 13-valent pneumococcal conjuage vaccine and 23-valent penumococcal polysaccharide vaccine among adults aged ≥65 years: recommendations of the Advisory Committe on Immunization Practices (ACIP). MMWR;2014:63: 822-25.

2. Bonten MJM, Huijts, M, Bolkenbaas C, et al. Polysaccharide conjugate vaccine against pneumococcal pneumonia in adults. N Engl J Med 2015;372:1114-25.

 

What’s the latest on vaccination of adults 65 years old or over with conjugated pneumococcal vaccine?