Cost effectiveness of pneumococcal urinary antigen in Emergency Department: a pragmatic real-life study

Community-acquired pneumonia (CAP) is frequent and can be life-threatening. Streptococcus pneumoniae is the main bacteria involved, and is susceptible to penicillin A. Rapid microbiological diagnosis could then help reduce the antimicrobial spectrum. The pneumococcal urinary antigen (PUA) test is fast and easy to perform, but its impact on antimicrobial prescription and cost-effectiveness in emergency departments (ED) is not well known. We performed a pragmatic real life retrospective study in an adult ED to assess its usefulness: proportion of positive results, impact on antimicrobial prescriptions and cost-effectiveness. Over 3 years (from January 1st 2012 to December 31st 2014), 979 PUA tests were reutilized in our ED among 1224 patients who consulted for CAP; 51 (5.2%) were positive. Among them, 10 led to a modification of the antimicrobial treatment, but only 7 (14.3%) were in accordance with the results. The total cost of a PUA test is 27€. As only 7 PUA tests led to appropriate antimicrobial modification, we deemed that 972 had no impact, and the potential cost savings, if the test had not been used, would have been 26,244 € (972 × 27) during 3 years, that is 8748 € per year. Thus, it seems that the PUA test should not be generally used in the ED considering its low rate of positivity and the difficulties for physicians to adapt antibiotic treatment accordingly. This attitude change in utilization would lead to substantial cost savings.

Pneumococcal vertebral osteomyelitis and psoas abscess in a patient with systemic lupus erythematosus disclosing positivity of pneumococcal urinary antigen assay

A 53-year-old woman with systemic lupus erythematosus presented with a 3-day history of fever and coughing. Diagnosis of pneumococcal bronchitis was made based on symptoms and positivity of pneumococcal urinary antigen test. On day 3, severe low back pain acutely occurred. Pneumococcal vertebral osteomyelitis and psoas abscess was diagnosed 17 days later by yield of penicillin-susceptible S. pneumoniae strain in blood cultures and drainage fluid. Although pneumococcal urinary antigen test is a useful tool for the diagnosis of pneumococcal pneumonia, we should consider the possibility of pneumococcal infections other than pneumonia or overwhelming bacteremia in immunosuppressive patients when urinary antigen test is positive.

Performance of a pneumolysin enzyme-linked immunosorbent assay for diagnosis of pneumococcal infections

A pneumolysin-specific enzyme-linked immunosorbent assay (PLY-ELISA) for the detection of pneumolysin in urine was developed and evaluated in comparison with the commercially available Binax Now Streptococcus pneumoniae test (Binax, Portland, ME) for the diagnosis of pneumococcal infections. Assay sensitivity was evaluated using urine from 108 patients with culture-confirmed pneumococcal infections. In adults, the sensitivity and specificity of the PLY-ELISA were 56.6% and 92.2%, respectively. In children with nasopharyngeal pneumococcal carriage, PLY-ELISA and Binax Now S. pneumoniae test sensitivities were 62.5% and 87.5%, respectively, while specificities were 94.4% and 27.8%, respectively. In children with nonnasopharyngeal pneumococcal carriage, PLY-ELISA and Binax Now S. pneumoniae test sensitivities were 68.7% and 93.7%, respectively, and test specificities were 94.1% and 41.2%, respectively. The persistence of pneumolysin in urine of pneumococcal pneumonia patients decreased significantly after 4 to 6 days of treatment. Our data suggest that combining the high specificity of the PLY-ELISA with the high sensitivity of the Binax Now S. pneumoniae test would enable pneumococcal infections to be accurately diagnosed in children.

Assessment of a rapid urinary antigen detection by an immunochromatographic test for diagnosis of pneumococcal infection in children

The aim of the study was to evaluate the Binax Now rapid immunochromatographic test (ICT) for the detection of Streptococcus pneumoniae urinary antigen in children suffering from potentially pneumococcal infections. A total of 287 patients, with a median age of 34.9 months and divided into 3 groups, were studied; the first group of patients with a suspected pneumococcal infection (n = 112), the second group with infectious symptoms nonsuggestive of a pneumococcal infection (n = 54), and the third group was composed of asymptomatic children (n = 121). In group 1, sensitivity of ICT was 100% and specificity was 55.9% (95% confidence interval, 44.1- 67.7). Forty-six (85.1%) patients from the second group were true negatives. Twenty-five (20.7%) patients from the third study group were nasopharyngeal pneumococcal carriers, and the ICT was positive in 13 carriers (10.7%). The high sensitivity level of ICT in our study indicates that a negative test could rule out a pneumococcal infection, contrasted with a poor specificity.

[Contribution of urinary pneumococcal antigen detection combined with the research of legionella antigen for diagnosis of pneumonia in hospitalized patients]

AIM OF THE STUDY

Bacteriological confirmation of pneumonia (PNM) in hospitalized patients is often erratic or belated. Because of importance of prognosis, early adaptation of treatment requires an empirical antimicrobial therapy (generally aminopenicillin and macrolide combination). The starting therapeutic strategy should profit by a fast and reliable test asserting a pneumococcal etiology. The Binax Now S. pneumoniae (BNP) test allows an urinary pneumococcal antigen (UPA) detection using an immunochromatographic membrane assay within 15 minutes.

MATERIALS AND METHODS

We first evaluated the BNP test for 28 patients with pneumococcal PNM proved by culture, and 118 negative control patients without PNM. The BNP test was then evaluated by testing urine from 158 hospitalized patients with a clinical picture of PNM (community-acquired: 90, nosocomial: 68) for whom a research of urinary Legionella antigen (Binax Now) was prescribed and was positive for only two cases. 57 patients (36.1%) were hospitalized in ICU.

RESULTS

The sensitivity was 71.4% (85.7% for the 21 bacteriemic PNM), and the specificity was 98.3%; that is consistent with previous published data. Among the 158 patients with PNM, UPA was detected in 17 cases (10.8%): 15 within the community-acquired PNM (16.7%) and 2 (2.9%) within the nosocomial cases. The pneumococcal etiology was confirmed by bacteriological samples in 7/17 patients (6 by blood cultures). The 10 others showed clinical and radiological features in agreement with a pneumococcal PNM. Among the 141 patients with negative AUP, S. pneumoniae was isolated from 6 of them (2 in blood cultures).

CONCLUSION

The Binax Now S. pneumoniae test allowed a fast and reliable etiological diagnosis in 10.8% of hospitalized PNM (16.7% of the community-acquired cases) having a research of urinary Legionella antigen (conceiving with severity factors). So it could conduce to an improved adjustment of the starting antimicrobial therapy of hospitalized adult patients with PNM.

[Rapid identification of pneumococcal antigenes in urines by the Now Streptococcus pneumoniae Binax test]

Streptococcus pneumoniae is responsible for many infectious conditions but probably with an underestimated incidence especially because of the fragility of the bacteria. The present study has evaluated a new test which detects a pneumococcal antigen in urine (Now S.p Binax). Urine samples from 181 children and 40 adults have been tested. All the patients presented with typical clinical signs of pneumococcal infection. Sensitivity = 91.7 %; specificity = 54.2 %; positive predictive value = 50 %; and negative predictive value = 92.9 % have been observed. Although the sensitivity and specificity were lower than those announced by the manufacturer, the test is easy to handle and provides a rapid argument for the diagnosis of pneumococcal infection, especially in the case of invasive infections like meningitis and bacteraemia.

Evaluation of Binax now Streptococcus pneumoniae urinary antigen test in children in a community with a high carriage rate of pneumococcus

Pneumococcal antigen was present in urine from 49 of 102 well Gambian children. Eighty-nine of the 102 were nasopharyngeal carriers of pneumococci. The positive predictive value for carriage was 96%, and the negative predictive value was 22%. The test is not useful for predicting etiology of disease in populations with a high rate of nasopharyngeal carriage of pneumococci.

Monovalent latex agglutination reagents for the diagnosis of nonmeningitic pneumococcal infection

The pneumococcus is a leading cause of serious bacterial infection worldwide. Given the difficulties with available assays for the diagnosis of invasive nonmeningitic pneumococcal infection, we evaluated monovalent slide latex agglutination reagents among patients with blood culture-confirmed pneumococcal infection and control patients in Baltimore, Maryland, USA; São Paulo, Brazil; and Cairo, Egypt. Among 50 patients with invasive nonmeningitic pneumococcal infection, 23 had a positive urine test for a sensitivity of 46% (95% confidence intervals of 32% and 61%). Among 39 healthy children, 36 had a negative assay, for a specificity of 92% (95% confidence intervals of 78% and 98%). Among 80 children with pneumonia without a positive blood culture for Streptococcus pneumoniae, the specificity was 88% (95% confidence intervals of 78% and 94%). Although the assay was fairly specific, the positive predictive value using optimistic assumptions was only 73%-83%. This study suggests that this assay has a sensitivity and positive predictive value that may limit its value in some settings.

Effect of urine latex agglutination tests on the treatment of children at risk for invasive bacterial infection

BACKGROUND

Identifying febrile children with invasive bacterial infection is difficult in the absence of telltale physical findings. Urine latex agglutination (ULA) tests have been used for rapid, on-site identification of such children.

OBJECTIVES

To study the performance of ULA tests in identifying children with Haemophilus influenzae, Streptococcus pneumoniae, and group B streptococcus infection and to examine how the results of ULA tests affect patient treatment.

DESIGN

Retrospective review.

SETTING

Urban children's hospital.

PATIENTS

All emergency department and hospital patients tested by ULA in 1990, excluding patients in the neonatal units.

RESULTS

Of 1629 patients, 36 had positive tests (20 H influenzae, 5 S pneumoniae, and 11 group B streptococcus). Thirteen of these were false positive based on culture results. Although ULA tests demonstrated excellent specificity, their sensitivity was poor. Positive predictive values for bacteremia ranged from 0.346 to 0.600, and negative predictive values ranged from 0.972 to 0.997. The decision to treat with antibiotics was made before ULA test results were available in 19 (53%) of the 36 patients with positive test results. Of 1593 patients with negative test results, 1211 (76%) were admitted to the hospital, and approximately 81% were empirically treated with parenteral antibiotics.

CONCLUSIONS

In clinical practice, treatment and disposition decisions are frequently made without regard to ULA test results.

[Detection of pneumococcal capsular polysaccharide antigen in urine by counterimmunoelectrophoresis. Technical features and correlation with serotype]

The effectiveness of CIE in detecting capsular polysaccharide antigen of pneumococci in urine is revised. Using CIE, we studied urine samples from 57 patients with systemic pneumococcal infections, proved bacteriologically by means of isolation of the microorganisms from sterile sites. We compare the usefulness of CIE with the microorganism isolation from organic products. We also determine the sensitivity gain after passive diffusion at 4 degrees C and bright blue Coomasie staining (CBB R-250). We correlate the CIE results with the serotype of isolated pneumococci. CIE was positive in 17 of all 35 pneumonia cases (48.6%), in 2 of all 5 bacteremias (40%), 4 of all 15 meningitis (26.7%) and in none of all two peritonitis. Direct urine examination was positive in 12 out of 23 patients with positive CIE (52.2%) and concentrated urine in 22 patients (95.6%). Passive diffusion at 4 degrees C and CBB R-250 stain increases the positive rate of the test. The correlation of serotype with our results is difficult due to the wide variety of serotypes identified. However, particular serotypes such (3, 4 or 8) had been identified with increased sensitivity. Global sensitivity of CIE in detecting capsular polysaccharide antigen in urine samples is not high enough (40.3%), even under the best circumstances. Antigen detection in urine is more sensitive than blood cultures, and therefore we believe that could be used in clinical microbiology laboratories until a more effective method is available.