Diagnosis of Streptococcus pneumoniae Infections in Adults with Bacteremia and Community-Acquired Pneumonia: Clinical Comparison of Pneumococcal PCR and Urinary Antigen Detection

Abstract

The diagnosis of severe Streptococcus pneumoniae infection relies heavily on insensitive culture techniques. To improve the usefulness of PCR assays, we developed a dual-PCR protocol (targeted at pneumolysin and autolysin) for EDTA blood samples. This was compared to the Binax NOW S. pneumoniae urine antigen test in patients with bacteremic pneumococcal infections. Patients with nonbacteremic community-acquired pneumonia also were tested by these methods to determine what proportion could be confirmed as pneumococcal infections. A direct comparison was made in a group of patients who each had both tests performed. The Binax NOW S. pneumoniae urine antigen test was positive in 51 of 58 bacteremic pneumococcal cases (sensitivity, 88%; 95% confidence interval [CI], 77 to 95%), whereas the dual PCR was positive in 31 cases (sensitivity, 53.5%; 95% CI, 40 to 67%; P < 0.0001), and all of these had detectable urinary antigens. Both tests gave positive results in 2 of 51 control patients (referred to as other-organism septicemia), giving a specificity of 96% (95% CI, 86.5 to 99.5%). In 77 patients with nonbacteremic community-acquired pneumonia, urinary antigen was detected significantly more often (in 21 patients [27%]) than a positive result by the dual-PCR protocol (6 [8%]) (P ‫؍‬ 0.002). The development of a dual-PCR protocol enhanced the sensitivity compared to that of the individual assays, but it is still significantly less sensitive than the Binax NOW urine antigen test, as well as being more time-consuming and expensive. Urinary antigen detection is the nonculture diagnostic method of choice for patients with possible severe pneumococcal infection.

Randomised controlled trial and health economic evaluation of the impact of diagnostic testing for influenza, respiratory syncytial virus and Streptococcus pneumoniae infection on the management of acute admissions in the elderly and high-risk 18- to 64-year-olds

“…Although blood culture is used as the 'gold standard' for diagnosis of pneumococcal CAP in many studies, it has low sensitivity and premedication with antibiotics reduces it further. The observed sensitivity (57.1%, 95% CI 18.4% to 90.1%) and specificity (92.5%, 95% CI 90.6% to 94.1%) for the BinaxNOW urinary antigen detection test in our study are comparable to sensitivities of 75% to 88% 49,[156][157][158][159][160] compared with blood culture (or culture of blood and pleural aspirate) in previous studies. The BinaxNOW POCT has a high specificity, in excess of 90%, and contributed to a reduction in the spectrum of antibiotic cover of 41 of 474 episodes of CAP in one recent study.…”

“…Other investigators have evaluated different PCR methods on sputum -in general they have had good sensitivity but poor specificity, whereas PCRs that have been developed to evaluate blood have had poor sensitivity but good specificity. 49 The detection of S. pneumoniae antigens in the urine of patients with pneumonia has been extensively studied using a variety of techniques. Although the performance of most tests has been somewhat disappointing, the BinaxNOW ® urinary antigen test (Binax, Portland, ME, USA) that we used is simple to perform; it can detect the C polysaccharide cell wall antigen common to all S. pneumoniae strains and it provides results within 15 minutes.…”

HIV-Associated Bacterial Pneumonia

“…Foremost amongst these are: i) quantitative real-time PCR procedures for the detection of pneumococcal DNA in biological fluids; and ii) the BINAX NOW Streptococcus pneumoniae immunochromatographic procedure which detects the C-polysaccharide antigen in urine with good sensitivity and specificity in adult patients with invasive disease [73].…”

Clinical Potential of C-Reactive Protein and Procalcitonin Serum Concentrations To Guide Differential Diagnosis and Clinical Management of Pneumococcal and Legionella Pneumonia

“…Pneumonia was diagnosed on the basis of clinical criteria and laboratory evidence of infection and was confirmed by radiographic evidence. For species diagnosis, urinary antigen tests for S. pneumoniae or L. pneumophila, the latter detecting serotype 1 (BinaxNOW; Inverness Medical, ME), were used (1,4,5,10,17).Baseline laboratory parameters were determined by routine automated tests, and data were available from day 1 (admission) and days 5 to 7. PCT levels were determined by a timeresolved amplified cryptate emission technology assay (Brahms AG, Henningsdorf, Germany) (2).…”