Evaluation of a rapid test for the diagnosis of pneumococcal pneumonia

Evaluating the utility of Binax NOW Streptococcus pneumoniae urinary antigen test in adults with community acquired pneumonia in China

INTRODUCTION

Binax NOW rapid immunochromatographic membrane test (ICT), a rapid method for detection of Streptococcus pneumoniae antigen, has been used widely in Europe and America, but rarely in China.

OBJECTIVE

Our aim is to evaluate the utility of the ICT among adult patients with community acquired pneumonia (CAP) in China.

METHODS

Adult patients with CAP were prospectively recruited from 12 general hospitals. ICT tests were done in all patients and clinical data were recorded. Qualified sputum culture was used as the standard for determining the diagnostic usefulness of ICT test.

RESULT

Thousand hundred fifty four CAP patients were enrolled in analysis, with median (IQR) age of 48 (35) years. 276 (23.9%) patients had underling diseases, 770 (66.7%) had received antibiotics before ICT test. Overall, the positive rate of ICT test was 3.3%, with sensitivity and specificity 57.9% and 96.6%, respectively. Disease severity, chronic obstructive pulmonary disease (COPD), increased age; respiratory rate (RR), neutrophil ratio, blood urea nitrogen (BUN), procalcitonin (PCT) and the decreased oxygenation index were associated with positive results of ICT tests. Patients with BUN >7 mmol/L, CURB-65 3-5, PCT > 2ng/mL were the top three groups with highest positive rate of ICT test (22.6%, 22.2% and 21.1% respectively).

CONCLUSION

ICT test has a moderate sensitivity and high specificity in adults with CAP in China. Patients classified as sever pneumonia, or those with BUN > 7 mmol/L, or PCT > 2 ng/mL are more likely to have positive results.

NutriPhone: a mobile platform for low-cost point-of-care quantification of vitamin B12 concentrations

Vitamin B12 is necessary for formation of red blood cells, DNA synthesis, neural myelination, brain development, and growth. Vitamin B12 deficiency is often asymptomatic early in its course; however, once it manifests, particularly with neurological symptoms, reversal by dietary changes or supplementation becomes less effective. Access to easy, low cost, and personalized nutritional diagnostics could enable individuals to better understand their own deficiencies as well as track the effects of dietary changes. In this work, we present the NutriPhone, a mobile platform for the analysis of blood vitamin B12 levels in 15 minutes. The NutriPhone technology comprises of a smartphone accessory, an app, and a competitive-type lateral flow test strip that quantifies vitamin B12 levels. To achieve the detection of sub-nmol/L physiological levels of vitamin B12, our assay incorporates an innovative "spacer pad" for increasing the duration of the key competitive binding reaction and uses silver amplification of the initial signal. We demonstrate the efficacy of our NutriPhone system by quantifying physiologically relevant levels of vitamin B12 and performing human trials where it was used to accurately evaluate blood vitamin B12 status of 12 participants from just a drop (~40 μl) of finger prick blood.

Utility of a Sputum Antigen Detection Test in Pneumococcal Pneumonia and Lower Respiratory Infectious Disease in Adults

OBJECTIVE

To compare the utility of Gram staining, a urinary antigen detection kit and a sputum antigen detection kit were examined for the rapid and early detection of pneumococcal pneumonia and lower respiratory infectious diseases.

METHODS

A newly developed sputum pneumococcal antigen detection kit (RAPIRUN), Gram staining, and urinary antigen detection kit (BinaxNOW) were comparatively evaluated for their ability to detect Streptococcus pneumoniae in patients with pneumonia or lower respiratory tract infection. Sputum culture results were used as a standard for comparison. Furthermore, the pneumococcus-positive rates in culture and rapid tests were compared using polymerase chain reaction (PCR) as a reference.

RESULTS

Of the 169 patients studied, 54 (32.0%) tested positive for S. pneumoniae in culture. S. pneumoniae detection sensitivities for Gram staining, RAPIRUN, and BinaxNOW were 75.9%, 90.7%, and 53.7%, respectively; thus, RAPIRUN had a significantly higher sensitivity than BinaxNOW (p<0.001). For patients with ≥10(5) copies/μg of pneumococcal surface protein A DNA PCR analysis, the detection rates of culture, Gram staining, and RAPIRUN were 85.2%, 72.1%, and 82.0%, respectively, however, the detection rate of BinaxNOW was only 47.5%. Comparisons among 45 patients with culture-positive pneumococcal pneumonia revealed that RAPIRUN had a significantly higher detection rate than BinaxNOW in the mild cases (p<0.006), regardless of the number of days from onset (p<0.03).

CONCLUSION

RAPIRUN is a rapid testing kit that detects S. pneumoniae in sputum with a high sensitivity and specificity. It is a particularly more useful detection kit than BinaxNOW for early and mild community-acquired pneumonia in pre-treatment patients whose sputum specimens can be obtained.

Sensitive multiplex PCR assay to differentiate Lyme spirochetes and emerging pathogens Anaplasma phagocytophilum and Babesia microti

Background

The infection with Borrelia burgdorferi can result in acute to chronic Lyme disease. In addition, coinfection with tick-borne pathogens, Babesia species and Anaplasma phagocytophilum has been increasing in endemic regions of the USA and Europe. The currently used serological diagnostic tests are often difficult to interpret and, moreover, antibodies against the pathogens persist for a long time making it difficult to confirm the cure of the disease. In addition, these tests cannot be used for diagnosis of early disease state before the adaptive immune response is established. Since nucleic acids of the pathogens do not persist after the cure, DNA-based diagnostic tests are becoming highly useful for detecting infectious diseases.

Results

In this study, we describe a real-time multiplex PCR assay to detect the presence of B. burgdorferi, B. microti and A. phagocytophilum simultaneously even when they are present in very low copy numbers. Interestingly, this quantitative PCR technique is also able to differentiate all three major Lyme spirochete species, B. burgdorferi, B. afzelii, and B. garinii by utilizing a post-PCR denaturation profile analysis and a single molecular beacon probe. This could be very useful for diagnosis and discrimination of various Lyme spirochetes in European countries where all three Lyme spirochete species are prevalent. As proof of the principle for patient samples, we detected the presence of low number of Lyme spirochetes spiked in the human blood using our assay. Finally, our multiplex assay can detect all three tick-borne pathogens in a sensitive and specific manner irrespective of the level of each pathogen present in the sample. We anticipate that this novel diagnostic method will be able to simultaneously diagnose early to chronic stages of Lyme disease, babesiosis and anaplasmosis using the patients’ blood samples.

Conclusion

Real-time quantitative PCR using specific primers and molecular beacon probes for the selected amplicon described in this study can detect three tick-borne pathogens simultaneously in an accurate manner.

Pneumococcal immune evasion: ZmpC inhibits neutrophil influx

Neutrophil recruitment is essential in clearing pneumococcal infections. The first step in neutrophil extravasation involves the interaction between P-selectin on activated endothelium and P-Selectin Glycoprotein 1 (PSGL-1) on neutrophils. Here, we identify pneumococcal Zinc metalloproteinase C as a potent inhibitor of PSGL-1. ZmpC degrades the N-terminal domain of PSGL-1, thereby disrupting the initial rolling of neutrophils on activated human umbilical vein endothelial cells. Furthermore, mice infected with wild-type strain in the model of pneumococcal pneumonia showed lower lungs neutrophil infiltration compare to animals infected with ZmpC mutant. In addition, we confirmed the association of zmpC with serotype 8 and 11A and found it to be associated with serotype 33F as well. In conclusion, wereport PSGL-1 as a novel target for ZmpC and show that ZmpC inhibits neutrophil extravasation during pneumococcal pneumonia.