Urine antigen tests for the diagnosis of respiratory infections: legionellosis, histoplasmosis, pneumococcal pneumonia

Urinary leptospiral sphingomyelinases as diagnostic markers of leptospirosis in dengue patients co-infected with leptospirosis

The study aims to evaluate the diagnostic potential of pathogen-specific leptospiral sphingomyelinases, LipL32, LipL41, and HbpA in human patients with dengue-leptospirosis coinfection. Patients (n-86), upon clinical evaluation, were categorized into Group I (n-37; leptospirosis), Group II (n-39; dengue-leptospirosis coinfection), and Group III (n-10; negative for both dengue and leptospirosis). ELISA identified significant levels of the four leptospiral antigens in the urine of Group I and II, but not in Group III patients. Immunoblot analysis of the urinary proteins with specific antibodies identified the tissue-damaging true sphingomyelinases Sph2 and pore-forming SphH. Urinary leptospiral antigens identified patients with leptospirosis and with dengue-leptospirosis coinfection. Patients with renal damage and proteinuria showed high urinary excretion of anti-leptospiral antibodies, with markedly low values in the serum. Proteinuria resulted in the loss of the circulating proteins, reflected by the low levels of anti-leptospiral antibodies in serum, with urine showing albumin and high levels of anti-leptospiral antibodies. IMPORTANCE: The study highlights the diagnostic potential of all four leptospiral antigens. Since early detection of urinary sphingomyelinases is possible, their diagnostic and prognostic potential can be evaluated on a larger sample size. Non-invasive, point-of-care diagnostic devices can be developed for use in endemic regions, particularly during monsoon seasons.

Acute Lung Injury in Immunocompromised Patients

Acute lung injury is a devastating complication when occurring in immunocompromised patients. The incidence appears to be increasing as more patients survive for longer in this susceptible state. Being aware of potential causes of acute lung injury may lead to earlier recognition and diagnosis. Infection is a common cause of acute lung injury and needs to be considered in the diagnostic algorithm. Management involves use of supportive ventilatory strategies and potentially pharmacologic therapies.

Harnessing the host response for precision infectious disease diagnosis

SUMMARYDetection of the presence of infection and its etiology must be accurate and timely to facilitate appropriate antimicrobial use. Diagnostic strategies that rely solely on pathogen detection often are insufficient due to poor test characteristics, inability to differentiate colonization from infection, or protracted delay to result. Understanding the human response across different pathogens on a clinical and molecular level can provide more accurate, timely, and useful answers, especially in critical illness and diagnostic uncertainty. Improvements in understanding the human immune response including genomics, protein analysis, gene expression, and cellular morphology have led to rapid innovation of new host response-based diagnostic tests. This review describes the limitations of pathogen-focused technology and the benefits of examining the breadth of immune response to diagnose infection. It then explores biomarkers that have been studied for this purpose and scrutinizes the performance of host-based multianalyte testing. Currently cleared diagnostics and those in late-stage development are described in depth, with a focus on the purpose of testing and its utility for clinicians. Finally, it concludes by examining opportunities for further host response-derived diagnostic innovation.

Diagnostic accuracy of a novel lateral flow assay for histoplasmosis

Antigen testing is an important diagnostic tool for histoplasmosis but has limited availability globally. We evaluated the OIDx urine lateral flow antigen assay among 204 persons suspected to have histoplasmosis. Among patients with proven histoplasmosis, sensitivity was 33.3% (3/9, 95% CI 7.5%-70.1%) and specificity 80.5% (157/195, 95% CI 74.3%-85.8%). The MiraVista urine antigen test had better specificity (96.9%) and equal sensitivity. The OIDx test demonstrated 33.3% (3/9) positive agreement and 84.0% (163/194) negative agreement with the MiraVista test. These results should be considered in the context of our low HIV prevalence population with a mixture of pulmonary and disseminated disease.

Diagnosis and Therapy of Community-Acquired Pneumonia in the Emergency Department: A Retrospective Observational Study and Medical Audit

BACKGROUND

Despite advances in therapy, community-acquired pneumonia (CAP) is still associated with significant morbidity and mortality. Several studies conducted in different countries have reported suboptimal adherence to the guidelines. However, there are currently no available data on adherence to CAP guidelines specifically in Switzerland.

OBJECTIVES

The aim of this study was to audit the quality of diagnosis and therapy of CAP at a Swiss general hospital.

METHODS

A retrospective, observational, single-center cohort study was conducted, including patients older than 18 years diagnosed with CAP and admitted to a medical ward throughout 2019 without prior antibiotic therapy prescribed by their general practitioner (GP). The baseline characteristics of the patients were analyzed, and the diagnostic workup and treatment were compared to the Swiss guidelines for CAP.

RESULTS

A total of 254 patients diagnosed with CAP were included in this study (median age 78 years, 51.6% males). Atypical pneumonia was diagnosed in 4% of patients, while an organism was identified in 33% of cases, with Streptococcus pneumoniae being the most frequently detected pathogen (57%). A chest image was taken in almost all patients. Documentation of respiratory rate was missing in 23% of cases. Procalcitonin was measured in 23.2% of cases. Pneumococcal and legionella urinary antigen testing was performed on approximately 90% of all patients and blood cultures were drawn in approximately 80% of patients. In 39% of cases, arterial blood gas analysis was performed. Guideline adherence for the administration of empiric antibiotics was documented/recorded in 75% of cases. Twelve different antibiotic regimens were administered, and they were mostly amoxicillin/clavulanate with or without macrolides, as suggested by the guidelines. In particular, the use of ceftriaxone was higher (19.7%) compared to the Swiss guidelines. The average length of antibiotic therapy was longer (8.2 days) compared to the guidelines (5-7 days). Oral steroid therapy was administered to 29.1% of patients, including to 75% of those diagnosed with COPD.

CONCLUSION

Overall, guideline adherence was moderately low, especially with regards to the assessment of respiratory rate, performance of arterial blood gas analysis, and sputum collection. Regarding antibiotic therapy, the use of ceftriaxone and the length of antibiotic therapy should be reduced. Further research is needed to identify the reasons for guideline non-adherence, and to find effective measures for the improvement of guideline adherence.

Legionella pneumophila Infections during a 7-Year Retrospective Analysis (2016-2022): Epidemiological, Clinical Features and Outcomes in Patients with Legionnaires' Disease

Legionella pneumophila (LP) is one of the main causative agents of community-acquired pneumonia in Europe and its fifth bacterial cause in Italy (4.9%). We conducted a seven year retrospective analysis of LP infection serogroup 1 in Asti, Piedmont, between 2016 and 2022. Patients were included if they tested positive for the Legionella urinary antigen. Clinical, laboratory, and radiologic data were analyzed to describe the risk factors for mortality. Fifty patients with LD were collected, mainly male, with a median age of 69 years. The main comorbidities were cardiovascular diseases (50%), pulmonary diseases (26%), and neurological diseases (12%). The most common clinical presentations were fever, respiratory, gastrointestinal, and neurologic symptoms. Older age (p = 0.004), underlying cardiovascular diseases (p = 0.009), late diagnosis at admission (p = 0.035), and neurological symptoms at diagnosis (p = 0.046) were more common in the non-survivor group. Moreover, a septic-shock presentation or the need for non-invasive ventilation at admission were associated with a higher mortality. No considerable differences in the biochemical data were found between the two groups except for the median neutrophil count, lymphocyte count, neutrophil-to-lymphocyte ratio, and PCT value. We did not find any differences in mortality related to the choice of antibiotic regimen. Differences in outcome were associated with the median duration of treatment (p =< 0.001) but not to the choice of antibiotic regimen (mainly levofloxacin or azithromycin). In conclusion, early individuation of the wide spectrum of clinical characteristics of LP infection such as respiratory, cardiac, and neurological manifestations of the patient's comorbidities, and significant biochemical data should help clinicians flag high risk patients and potentially improve their outcome.

Urine Metabolite of Mice with Orientia tsutsugamushi Infection

Scrub typhus is an acute febrile, mite-borne disease endemic to the Asia-Pacific region. In South Korea, it is a seasonal disease that occurs frequently in the autumn, and its incidence has increased steadily. In this study, we used a liquid chromatography and flow injection analysis-tandem mass spectrometry-based targeted urine metabolomics approach to evaluate the host response to Orientia tsutsugamushi infection. Balb/c mice were infected with O. tsutsugamushi Boryong, and their urine metabolite profile was examined. Metabolites that differed significantly between the experimental groups were identified using the Kruskal-Wallis test. Sixty-five differential metabolites were identified. The principal metabolite classes were acylcarnitines, glycerophospholipids, biogenic amines, and amino acids. An ingenuity pathway analysis revealed that several toxic (cardiotoxic, hepatotoxic, and nephrotoxic) metabolites are induced by scrub typhus infection. This is the first report of urinary metabolite biomarkers of scrub typhus infection and it enhances our understanding of the metabolic pathways involved.

Diagnostic Study to Assess the Performance of a New Urinary Legionella Antigen Test-A National Study in Three Referral University Hospitals in Austria during 2014-2017

BACKGROUND

We evaluated the performance of a rapid diagnostic antigen test (Coris) as an index test versus the urinary Antigen ELISA (Bartels) as the reference test.

METHODS

Prospective diagnostic accuracy study (2014-2017) at three university hospitals in Austria.

RESULTS

A total of 996 patients were included in the study. Legionellosis was diagnosed in 49/996 (4.9%) using the reference test. The sensitivity and specificity of the Coris test were 75.5% (95% CI 61.1-86.7%) and 100% (95%CI 99.6-100%), respectively. The PPV was 100% and when using the lower 95% CI limit of the estimate for sensitivity, the resulting PPV was 61.1%. The NPV was 98.7% and the accuracy was 98.8%. The index test showed a PPV > 97% during the period of summer and autumn (May through November) and ≥88% during winter (December through February). The NPV was >97% during all of the periods. The median of the monthly incidence in the general population was 0.1 per 100,000 (IQR 0.1; 0.3).

CONCLUSION

The new rapid test gave a high level of diagnostic accuracy in a rapid fashion. The test can be applied at the bedside by non-laboratory staff.

Urine is a viral antigen reservoir in hepatitis E virus infection

BACKGROUND AND AIMS

HEV ORF2 antigen (Ag) in serum has become a tool for diagnosing current HEV infection. Particularly, urinary shedding of HEV Ag has been gaining increasing interest. We aim to uncover the origin, antigenicity, diagnostic performance, and diagnostic significance of Ag in urine in HEV infection.

APPROACH AND RESULTS

Clinical serum and urine samples from patients with acute and chronic HEV infection were analyzed for their Ag levels. Ag in urine was analyzed by biochemical and proteomic approaches. The origin of urinary Ag and Ag kinetics during HEV infection was investigated in mouse and rabbit models, respectively. We found that both the Ag level and diagnostic sensitivity in urine were higher than in serum. Antigenic protein in urine was an E2s-like dimer spanning amino acids 453-606. pORF2 entered urine from serum in mice i.v. injected with pORF2. Ag in urine originated from the secreted form of pORF2 (ORF2^S ) that abundantly existed in hepatitis E patients' serum. HEV Ag was specifically taken up by renal cells and was disposed into urine, during which the level of Ag was concentrated >10-fold, resulting in the higher diagnosing sensitivity of urine Ag than serum Ag. Moreover, Ag in urine appeared 6 days earlier, lasted longer than viremia and antigenemia, and showed good concordance with fecal RNA in a rabbit model.

CONCLUSIONS

Our findings demonstrated the origin and diagnostic value of urine Ag and provided insights into the disposal of exogenous protein of pathogens by the host kidney.

Urinary Antigen Testing for Respiratory Infections: Current Perspectives on Utility and Limitations

Pneumonia is a leading cause of hospitalization and death due to infection worldwide. Streptococcus pneumoniae and Legionella pneumophila remain among the most commonly identified bacterial pathogens. Unfortunately, more than half of all pneumonia cases today lack an etiologic diagnosis due to limitations in traditional microbiological methods like blood and sputum cultures, which are affected by poor sample collection, prior antibiotic administration, and delayed processing. Urinary antigen tests (UATs) for S. pneumoniae and L. pneumophila have emerged as powerful tools for improving the diagnosis of bacterial respiratory infections, enabling physicians to administer early directed therapy and improve antimicrobial stewardship. UATs are simple, rapid, and non-invasive diagnostic tests with high specificity (>90%) and moderate sensitivity (<80%). The potential impact of urinary antigen testing is especially significant for respiratory infections caused by Legionella. While all recommended community-acquired pneumonia (CAP) therapies are adequate for treating pneumococcal pneumonia, only certain antibiotics are effective against Legionella. Delayed therapy for Legionella is associated with worse clinical outcomes, which underscores the importance of rapid diagnostic methods like UATs. Despite their potential impact, current American Thoracic Society and Infectious Diseases Society of America (ATS/IDSA) guidelines argue against the routine use of urinary antigen testing for S. pneumoniae and L. pneumophila, except in patients with severe CAP and those with epidemiological risk factors for Legionella. Further research is necessary to evaluate the impact of early targeted treatment due to positive UAT results, as well as optimal strategies for UAT utilization. The purpose of this review is to summarize the UATs available for bacterial respiratory infections, describe current guidelines on their usage, and assess their impact on clinical outcomes and targeted therapy.

New Microbiological Techniques for the Diagnosis of Bacterial Infections and Sepsis in ICU Including Point of Care

Purpose of Review

The aim of this article is to review current and emerging microbiological techniques that support the rapid diagnosis of bacterial infections in critically ill patients, including their performance, strengths and pitfalls, as well as available data evaluating their clinical impact.

Recent Findings

Bacterial infections and sepsis are responsible for significant morbidity and mortality in patients admitted to the intensive care unit and their management is further complicated by the increase in the global burden of antimicrobial resistance. In this setting, new diagnostic methods able to overcome the limits of traditional microbiology in terms of turn-around time and accuracy are highly warranted. We discuss the following broad themes: optimisation of existing culture-based methodologies, rapid antigen detection, nucleic acid detection (including multiplex PCR assays and microarrays), sepsis biomarkers, novel methods of pathogen detection (e.g. T2 magnetic resonance) and susceptibility testing (e.g. morphokinetic cellular analysis) and the application of direct metagenomics on clinical samples. The assessment of the host response through new “omics” technologies might also aid in early diagnosis of infections, as well as define non-infectious inflammatory states.

Summary

Despite being a promising field, there is still scarce evidence about the real-life impact of these assays on patient management. A common finding of available studies is that the performance of rapid diagnostic strategies highly depends on whether they are integrated within active antimicrobial stewardship programs. Assessing the impact of these emerging diagnostic methods through patient-centred clinical outcomes is a complex challenge for which large and well-designed studies are awaited.

Diagnosis of Pulmonary Infections Due to Endemic Fungi

Endemic mycoses including Histoplasma, Blastomyces, Coccidioides, Paracoccidioides, and Talaromyces are dimorphic fungi that can cause a variety of clinical manifestations, including respiratory infections. Their pulmonary presentations are variable, and diagnosis is often delayed as they can mimic other infectious and non-infectious causes of pulmonary disease. Delay in diagnosis can lead to unnecessary antibiotic use, repeat hospitalizations, and increased morbidity and mortality. The diagnosis of endemic fungal pulmonary infections often relies on multiple diagnostic tests including culture, tissue histopathology, antigen assays, and antibody assays. Due to the increased use of immunosuppressive agents and the widening geographic ranges where these infections are being found, the prevalence of endemic fungal infections is increasing. Physicians need to be aware of the clinical manifestations of pulmonary infections due to endemic fungal in order to ensure that the proper diagnostic work up is obtained promptly. A high index of suspicion is particularly important in patients with suspected pulmonary infections who have failed to improve despite antibiotics in the appropriate setting. We present a review diagnostic testing for pulmonary infections due to endemic mycoses.

Urinary biomarkers of mycobacterial load and treatment response in pulmonary tuberculosis

BACKGROUNDControl of the tuberculosis (TB) pandemic remains hindered in part by a lack of simple and accurate measures of treatment efficacy, as current gold standard markers rely on sputum-based assays that are slow and challenging to implement. However, previous work identified urinary N1, N12-diacetylspermine (DiAcSpm), neopterin, hydroxykynurenine, N-acetylhexosamine, ureidopropionic acid, sialic acid, and mass-to-charge ratio (m/z) 241.0903 as potential biomarkers of active pulmonary TB (ATB). Here, we evaluated their ability to serve as biomarkers of TB treatment response and mycobacterial load.METHODSWe analyzed urine samples prospectively collected from 2 cohorts with ATB. A total of 34 study participants from African countries treated with first-line TB therapy rifampin, isoniazid, pyrazinamide, and ethambutol (HRZE) were followed for 1 year, and 35 participants from Haiti treated with either HRZE or an experimental drug were followed for 14 days. Blinded samples were analyzed by untargeted HPLC-coupled high-resolution TOF-mass spectrometry.RESULTSUrinary levels of all 7 molecules significantly decreased by week 26 of successful treatment (P = 0.01 to P < 0.0001) and positively correlated with sputum mycobacterial load (P < 0.0001). Urinary DiAcSpm levels decreased significantly in participants treated with HRZE as early as 14 days (P < 0.0001) but remained unchanged in cases of ineffective therapy (P = 0.14).CONCLUSIONUrinary DiAcSpm, neopterin, hydroxykynurenine, N-acetylhexosamine, ureidopropionic acid, sialic acid, and m/z 241.0903 reductions correlated with successful anti-TB treatment and sputum mycobacterial load. Urinary DiAcSpm levels exhibited reductions capable of differentiating treatment success from failure as early as 2 weeks after the initiation of chemotherapy, advocating its further development as a potentially simple, noninvasive biomarker for assessing treatment response and bacterial load.FUNDINGThis work was supported by the Clinical and Translational Science Center at Weill Cornell College of Medicine (NIH/NCATS 1 UL1 TR002384-02 and KL2TR000458), the Department of Defense (PR170782), the National Institute of Allergy and Infectious Disease grants (NIAID T32AI007613-16, K24 AI098627, and K23 AI131913), the NIH Fogarty International Center grants (R24 TW007988 and TW010062), NIH grant (R01 GM135926), the Abby and Howard P. Milstein Program in Chemical Biology and Translational Medicine, and the Tuberculosis Research Units Networks (TBRU-N, AI111143).

Immunochromatography for the diagnosis of Mycoplasma pneumoniae infection: A systematic review and meta-analysis

The aim of this study was to evaluate the diagnostic performance of immunochromatographic tests (ICTs) for the detection of Mycoplasma pneumoniae. Medline/Pubmed, Embase, the Cochrane Library, and ISI Web of Science were searched through June 12, 2019 for relevant studies that used ICTs for the detection of M. pneumoniae infection with polymerase chain reaction (PCR) or microbial culturing as reference standards. Pooled diagnostic accuracy with 95% confidence interval (CI) was calculated using a bivariate random effects model. We also constructed summary receiver operating characteristic curves and calculated the area under the curve (AUC). Statistical heterogeneity was evaluated by χ² test or Cochrane’s Q test. Thirteen studies including 2,235 samples were included in the meta-analysis. The pooled sensitivity and specificity for diagnosing M. pneumoniae infection were 0.70 (95% CI: 0.59–0.79) and 0.92 (95% CI: 0.87–0.95), respectively. The positive likelihood ratio (LR) was 8.94 (95% CI: 4.90–14.80), negative LR 0.33 (95% CI: 0.22–0.46), diagnostic odds ratio 29.20 (95% CI: 10.70–64.20), and AUC 0.904. In subgroup analysis, ICTs demonstrated similar pooled sensitivities and specificities in populations of children only and mixed populations (children + adults). Specimens obtained from oropharyngeal swabs exhibited a higher sensitivity and specificity than those of nasopharyngeal swab. Moreover, pooled estimates of sensitivity and accuracy for studies using PCR as a reference standard were higher than those using culture. The pooled sensitivity and specificity of Ribotest Mycoplasma^®, the commercial kit most commonly used in the included studies, were 0.66 and 0.89, respectively. Overall, ICT is a rapid user-friendly method for diagnosing M. pneumoniae infection with moderate sensitivity, high specificity, and high accuracy. This suggests that ICT may be useful in the diagnostic workup of M. pneumoniae infection; however, additional studies are needed for evaluating the potential impact of ICT in clinical practice.

Optimal approaches to preventing severe community-acquired pneumonia

Introduction: Community-acquired pneumonia (CAP) has the highest rate of mortality of all infectious diseases, especially among the elderly. Severe CAP (sCAP) is defined as a CAP in which intensive care management is required and is associated with an unfavorable clinical course. Areas covered: This review aims to identify prevention strategies for reducing the incidence of CAP and optimized management of sCAP. We highlight the main prevention approaches for CAP, focusing on the latest vaccination plans and on the influence of health-risk behaviors. Lastly, we report the latest recommendations about the optimal approach for sCAP when CAP has already been diagnosed, including prompt admission to ICU, early empirical antibiotic therapy, and optimization of antibiotic use. Expert opinion: Despite improvements in the diagnosis and treatment of sCAP, more efforts are needed to combat preventable causes, including the implementation and improvement of vaccine coverage, anti-tobacco campaigns and correct oral hygiene. Moreover, future research should aim to assess the benefits of early antimicrobial therapy in primary care. Pharmacokinetic studies in the target population may help clinicians to adjust dosage regimens in critically ill patients with CAP and thus reduce rates of treatment failure.

Rapid Streptococcus Pneumonia Antigen Detection on Postmortem Urine in a Death Due to Pneumococcal Meningitis

Streptococcus pneumoniae is the leading cause of adult bacterial meningitis. Differing from Neisseria meningitidis (the second most common cause of acute bacterial meningitis), contact tracing and chemoprophylaxis are not required. At postmortem, the differentiation between S. pneumoniae and N. meningitidis is traditionally done by culture and polymerase chain reaction performed on blood or cerebrospinal fluid, but may take hours, if not days, to analyze. We present a death from bacterial meningitis in a 73-year-old woman in which a rapid urinary pneumococcal antigen testing was able to identify S. pneumoniae as the causative organism within 1 hour. This was confirmed by subsequent brain swab culture. The rapid urinary pneumococcal antigen test in the case prevented the need for contact tracing and chemoprophylaxis. This case highlights the potential use of this test to rapidly identify the culprit organism at postmortem examination when acute bacterial meningitis is detected.

Candidate Treponema pallidum biomarkers uncovered in urine from individuals with syphilis using mass spectrometry

AIM

A diagnostic test that could detect Treponema pallidum antigens in urine would facilitate the prompt diagnosis of syphilis.

MATERIALS & METHODS

Urine from 54 individuals with various clinical stages of syphilis and 6 controls were pooled according to disease stage and interrogated with complementary mass spectrometry techniques to uncover potential syphilis biomarkers.

RESULTS & CONCLUSION

In total, 26 unique peptides were uncovered corresponding to four unique T. pallidum proteins that have low genetic sequence similarity to other prokaryotes and human proteins. This is the first account of direct T. pallidum protein detection in human clinical samples using mass spectrometry. The implications of these findings for future diagnostic test development is discussed. Data are available via ProteomeXchange with identifier PXD009707.

Mass Spectrometric Identification of Urinary Biomarkers of Pulmonary Tuberculosis

Background

Tuberculosis (TB) is the leading infectious cause of death worldwide. A major barrier to control of the pandemic is a lack of clinical biomarkers with the ability to distinguish active TB from healthy and sick controls and potential for development into point-of-care diagnostics.

Methods

We conducted a prospective case control study to identify candidate urine-based diagnostic biomarkers of active pulmonary TB (discovery cohort) and obtained a separate blinded “validation” cohort of confirmed cases of active pulmonary TB and controls with non-tuberculous pulmonary disease for validation. Clean-catch urine samples were collected and analyzed using high performance liquid chromatography-coupled time-of-flight mass spectrometry.

Results

We discovered ten molecules from the discovery cohort with receiver-operator characteristic (ROC) area-under-the-curve (AUC) values >85%. These 10 molecules also significantly decreased after 60 days of treatment in a subset of 20 participants followed over time. Of these, a specific combination of diacetylspermine, neopterin, sialic acid, and N-acetylhexosamine exhibited ROC AUCs >80% in a blinded validation cohort of participants with active TB and non-tuberculous pulmonary disease.

Conclusion

Urinary levels of diacetylspermine, neopterin, sialic acid, and N-acetylhexosamine distinguished patients with tuberculosis from healthy controls and patients with non-tuberculous pulmonary diseases, providing a potential noninvasive biosignature of active TB.

Funding

This study was funded by Weill Cornell Medicine, the National Institute of Allergy and Infectious Diseases, the Clinical and Translational Science Center at Weill Cornell, the NIH Fogarty International Center grants, and the NIH Tuberculosis Research Unit (Tri-I TBRU).

•

Urinary levels of small metabolites appear capable of distinguishing cases of active pulmonary tuberculosis from sick and healthy controls.

•

Levels of these biomarkers decrease after 60 days of treatment in a longitudinal cohort of 20 participants.

•

- Many of the identified biomarkers are known inflammatory intermediates that may reflect a specific immune response to tuberculosis.

Urine tests are commonly used to enable non-invasive, rapid and point-of-care diagnosis of various infectious diseases. We identified diacetylspermine, neopterin, sialic acid and N-acetylhexosamine as potential urine-based biomarkers for tuberculosis from two independent patient cohorts. These metabolites are known inflammatory intermediates and appear to decrease with anti-tuberculosis therapy in a subset of participants followed over 2 months. If validated, these metabolites have potential to both improve our understanding of the immune reaction to active tuberculosis and facilitate the development of a much-needed clinical biomarker for tuberculosis.

Discovery of a unique Mycobacterium tuberculosis protein through proteomic analysis of urine from patients with active tuberculosis

Identification of pathogen-specific biomarkers present in patients' serum or urine samples can be a useful diagnostic approach. In efforts to discover Mycobacterium tuberculosis (Mtb) biomarkers we identified by mass spectroscopy a unique 21-mer Mtb peptide sequence (VVLGLTVPGGVELLPGVALPR) present in the urines of TB patients from Zimbabwe. This peptide has 100% sequence homology with the protein TBCG_03312 from the C strain of Mtb (a clinical isolate identified in New York, NY, USA) and 95% sequence homology with Mtb oxidoreductase (MRGA423_21210) from the clinical isolate MTB423 (identified in Kerala, India). Alignment of the genes coding for these proteins show an insertion point mutation relative to Rv3368c of the reference H37Rv strain, which generated a unique C-terminus with no sequence homology with any other described protein. Phylogenetic analysis utilizing public sequence data shows that the insertion mutation is apparently a rare event. However, sera from TB patients from distinct geographical areas of the world (Peru, Vietnam, and South Africa) contain antibodies that recognize a purified recombinant C-terminus of the protein, thus suggesting a wider distribution of isolates that produce this protein.

Novel potential serological prostate cancer biomarkers using CT100+ cancer antigen microarray platform in a multi-cultural South African cohort

There is a growing need for high throughput diagnostic tools for early diagnosis and treatment monitoring of prostate cancer (PCa) in Africa. The role of cancer-testis antigens (CTAs) in PCa in men of African descent is poorly researched. Hence, we aimed to elucidate the role of 123 Tumour Associated Antigens (TAAs) using antigen microarray platform in blood samples (N = 67) from a South African PCa, Benign prostatic hyperplasia (BPH) and disease control (DC) cohort. Linear (fold-over-cutoff) and differential expression quantitation of autoantibody signal intensities were performed. Molecular signatures of candidate PCa antigen biomarkers were identified and analyzed for ethnic group variation. Potential cancer diagnostic and immunotherapeutic inferences were drawn. We identified a total of 41 potential diagnostic/therapeutic antigen biomarkers for PCa. By linear quantitation, four antigens, GAGE1, ROPN1, SPANXA1 and PRKCZ were found to have higher autoantibody titres in PCa serum as compared with BPH where MAGEB1 and PRKCZ were highly expressed. Also, p53 S15A and p53 S46A were found highly expressed in the disease control group. Statistical analysis by differential expression revealed twenty-four antigens as upregulated in PCa samples, while 11 were downregulated in comparison to BPH and DC (FDR = 0.01). FGFR2, COL6A1and CALM1 were verifiable biomarkers of PCa analysis using urinary shotgun proteomics. Functional pathway annotation of identified biomarkers revealed similar enrichment both at genomic and proteomic level and ethnic variations were observed. Cancer antigen arrays are emerging useful in potential diagnostic and immunotherapeutic antigen biomarker discovery.

Selected Topics in Aerobic Bacteriology

Aerobic Gram-positive and Gram-negative bacteria can be important pathogens in the immunocompromised host. These bacteria can be found in many environments, as part of the normal microbiota of the human host and animals, in soil and water, on plants, on fomites in the hospital, and on hospital equipment. This review provides information from relevant studies about what are the most common aerobic bacteria associated with patients who have cancer and/or are being treated for it, or who have other diseases which lead to immunodeficiencies, such as HIV, multiple myeloma, aplastic anemia, chronic diseases, and aging. A discussion of the appropriate laboratory tests needed for diagnosis of aerobic infections and information about antibiotics and susceptibility testing are also included.

Characterization and evaluation of a novel immunochromatographic assay for pharyngeal Mycoplasmapneumoniae ribosomal protein L7/L12 antigens

Point-of-care testing for Mycoplasma pneumoniae infection may be ideal and useful because significant numbers of the cases will be seen as outpatients. Recently, a new immunochromatographic method (ICM) targeting M. pneumoniae ribosomal protein L7/L12 (RP-L7/L12) in pharyngeal swabs became available in Japan, although clinical data and basic information regarding efficacy and characterization of this ICM are limited. The present study examined the fate of M. pneumoniae RP-L7/L12 during in vitro growth and the correlation between M. pneumoniae concentration in clinical specimens and the sensitivity of the ICM test. The usefulness of the ICM was investigated in patients suspected of having M. pneumoniae pneumonia and upper respiratory tract infection (137 children and 39 adults). The limit of detection for the ICM test was 1.1×104 c.f.u. ml-1 of M. pneumoniae. Bacterial production of RP-L7/L12 correlated positively with the viable M. pneumoniae concentration in vitro; antigen was then degraded in culture broth, with an in vitro half-life of approximately 2 days. Five other Mycoplasma spp. and 14 representative respiratory pathogens were ICM assay negative at bacterial concentrations of 106 c.f.u. ml-1. The clinical sensitivity and specificity of the ICM assay were 57.1 % (20/35) and 92.2 % (130/141), respectively, in comparison with bacterial culture. Clinical specimens containing ≥106 c.f.u. ml-1 of M. pneumoniae burden were ICM positive in 13 of 18 cases (72.2 %). The ICM is a poorly sensitive but reasonably specific means for detecting M. pneumoniae infections.

Comparative Evaluation of the Novel bioNexia Legionella Test with the BinaxNOW Legionella Card Assay and the Sofia Legionella FIA Assay for Detection of Legionella pneumophila (Serogroup 1) Antigen in Urine Samples

A new immunochromatographic test (bioNexiaLegionella; bioMérieux) for the detection ofLegionella pneumophilaurinary antigen was evaluated in 255 urine samples. The results were compared with those obtained by the BinaxNOW and SofiaLegionellatests. The novel test compared well with those currently in use.

A Retrospective Study of the Clinical Burden of Hospitalized All-Cause and Pneumococcal Pneumonia in Canada

Background. Routine vaccination against Streptococcus pneumoniae is recommended in Canada for infants, the elderly, and individuals with chronic comorbidity. National incidence and burden of all-cause and pneumococcal pneumonia in Canada (excluding Quebec) were assessed. Methods. Incidence, length of stay, and case-fatality rates of hospitalized all-cause and pneumococcal pneumonia were determined for 2004-2010 using ICD-10 discharge data from the Canadian Institutes for Health Information Discharge Abstract Database. Population-at-risk data were obtained from the Statistics Canada census. Temporal changes in pneumococcal and all-cause pneumonia rates in adults ≥65 years were analyzed by logistic regression. Results. Hospitalization for all-cause pneumonia was highest in children <5 years and in adults >70 years and declined significantly from 1766/100,000 to 1537/100,000 per year in individuals aged ≥65 years (P < 0.001). Overall hospitalization for pneumococcal pneumonia also declined from 6.40/100,000 to 5.08/100,000 per year. Case-fatality rates were stable (11.6% to 12.3%). Elderly individuals had longer length of stay and higher case-fatality rates than younger groups. Conclusions. All-cause and pneumococcal pneumonia hospitalization rates declined between 2004 and 2010 in Canada (excluding Quebec). Direct and indirect effects from pediatric pneumococcal immunization may partly explain some of this decline. Nevertheless, the burden of disease from pneumonia remains high.

In vivo biosynthesis of terpene nucleosides provides unique chemical markers of Mycobacterium tuberculosis infection

Although small molecules shed from pathogens are widely used to diagnose infection, such tests have not been widely implemented for tuberculosis. Here we show that the recently identified compound, 1-tuberculosinyladenosine (1-TbAd), accumulates to comprise >1% of all Mycobacterium tuberculosis lipid. In vitro and in vivo, two isomers of TbAd were detected that might serve as infection markers. Using mass spectrometry and nuclear magnetic resonance, we established the structure of the previously unknown molecule, N(6)-tuberculosinyladenosine (N(6)-TbAd). Its biosynthesis involves enzymatic production of 1-TbAd by Rv3378c followed by conversion to N(6)-TbAd via the Dimroth rearrangement. Intact biosynthetic genes are observed only within M. tuberculosis complex bacteria, and TbAd was not detected among other medically important pathogens, environmental bacteria, and vaccine strains. With no substantially similar known molecules in nature, the discovery and in vivo detection of two abundant terpene nucleosides support their development as specific diagnostic markers of tuberculosis.