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016th ¡CID Abstracts/International Journal of Infectious Diseases 2IS (2014) 1-460
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Type: Poster Presentation
Final Abstract Number: 59.010 Session: Diagnosis Date: Saturday, April 5,2014 Time: 12:45-14:15 Room: Ballroom
Toward a rapid and accurate point-of-care test for active pulmonary tuberculosis: Multiplexed proteomic assay (SOMAscan™) of human serum for microbial and host markers
M.A. De Groote, L. Green, D. Sterling, R. Ostroff, N. Janjic, U. Ochsner
Somalogic, Boulder, USA
Background: A rapid, accurate, and inexpensive tuberculosis (TB) diagnostic test would allow earlier treatment and reduce transmission.
Methods & Materials: We used slow off-rate modified aptamers (SOMAmers) in a highly multiplexed proteomic assay (SOMAscan) to measure 1129 human proteins and 16 Mtb proteins in serum samples provided by the Foundation for Innovative New Diagnostics (FIND).
Results: Among the top host serum biomarkers distinguishing TB from non-TB regardless of the HIV status were kallistatin, TSP4, gelsolin, and CDON, which were lower in TB compared to non-TB, and LBP, ITI heavy chain H4, NPS-PLA2, and 1P-10, which were higher in TB.
A 9-marker model performed well in a training set of 173 TB vs. 160 non-TB samples (sens 89% / spec 88%, AUC = 0.94), which was confirmed in a blinded verification set of 132 TB vs. 118 non-TB (sens 80% / spec 84%, AUC = 0.88). Mtb pathogen-specific SOMAmers showed non-specific background in serum and are pending analytical optimization to improve performance. Additional work to improve sensitivity of the host markers is ongoing.
Conclusion: The discovery of robust, quantitative, non-culture based diagnostic biomarkers of active pulmonary TB has great potential to facilitate the rapid and accurate diagnosis of TB disease. Our goal is that a combined host and microbial point-of-care diagnostic test could ultimately be tested and applied in peripheral microscopy centers or in primary care clinics.
http://dx.doi.org/10.1016/j.ijid.2014.03.1172 Type: Poster Presentation
Final Abstract Number: 59.011 Session: Diagnosis Date: Saturday, April 5,2014 Time: 12:45-14:15 Room: Ballroom
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Identification and evaluation of Schistosoma mansoni proteins as diagnostic targets for schistosomiasis
P. Ogongo
Institute of Primate Research, Nairobi, Kenya
Background: Demonstration of schistosome eggs in stool/urine is the definitive clinical test for clinical examination of schisto-
somiasis but this test has low sensitivity. Antibody based assays cannot distinguish between past and active infections thus unsuitable for follow up after drug administration while molecular techniques are expensive and unavailable at the point of care centers. Bioinformatics and Proteomics can be used to characterize schistosome proteins from different life cycle stages that include worm gut, worm tegument, egg secretions or released products of dead eggs that are released into the bloodstream and/or urine forming good diagnostic targets.
Methods & Materials: We have identified five schistosome proteins; Cathepsin B (Sm31), Asaparaginyl endopeptidase (Sm32), schistosome alpha-2 macroglobulin, Sm LMWP and Sm200 tegument protein using these approaches. Peptide sequences from these proteins synthesized as multiple antigenic peptides (MAPs) or conjugated to carrier proteins were used to immunize rats and rabbits. Serum from immunized rats were used to test the suitability of these targets using Enzyme Assays, Blot Assays and Immunocytochemistry with worm sections.
Results: Results show that antibodies to MAPs have good specificity for the peptides and native schistosome antigens while coupling to carrier proteins improves the immunogenicity of the peptides.
Conclusion: This approach has shown that these peptides are possible diagnostic targets that can be developed further to assess their sensitivity aiming at developing an assay capable of detecting the lowest number of worms in the host.
http://dx.doi.org/10.1016/j.ijid.2014.03.1173 Type: Poster Presentation
Final Abstract Number: 59.012 Session: Diagnosis Date: Saturday, April 5, 2014 Time: 12:45-14:15 Room: Ballroom
Rapid detection of ESBL-producing Enterobacteriaceae from blood cultures: A prospective study
P. Nordmann1, L. Poirel1, L. Dortet2
1 University ofFribourg, Fribourg, Switzerland
2 Hopital de Bicetre, Kremlin-Bicetre, France
Background: Enterobacterial strains producing clavulanic-acid inhibited extended-spectrum beta-lactamases (ESBLs) are increasingly reported worldwide. The rapid detection of ESBL-producing Enterobacteriaceae responsible for bacteremia is of utmost importance since their successful treatment depends on prompt administration of the appropriate antimicrobial agents. The ESBL NDP test has been evaluated here prospectively to detect ESBL-producing Enterobacteriaceae directly from blood cultures.
Methods & Materials: From November 2012 to May 2013, the ESBL NDP test, a rapid chromogenic test based on detection of cefotaxime hydrolysis, was performed with 96 blood cultures positive for Gram negatives. Results of the ESBL NDP test, obtained in less than 30 min, were compared to those obtained with the double disk diffusion technique. All ESBLs were then characterized at the molecular level. Identification of the Gram-negative bacteria was also performed directly on positive blood cultures using MALDI-TOF technology, and confirmed by a biochemical identification.
Results: Eighteen blood cultures infected with ESBL-producing Enterobacteriaceae (15 CTX-M producing E. coli and 3 CTX-M producing K. pneumoniae) were correctly detected, whereas 78
16th ICID Abstracts/International Journal of Infectious Diseases 2IS (2014) 1-460
infected by non-ESBL-producing isolates gave negative results with the ESBL NDP test. Results of the ESBL NDP test were 100% correlated with those of the double disk-diffusion method with the main advantage that they were obtained in less than 30 min directly from the clinical sample versus an additive 24 h time of incubation for the double disk-diffusion method.
Conclusion: Using the ESBL NDP test, identification of an ESBL producer responsible for a bacteremia can be reduced from 2448 hours to 30 min with 100% sensibility, 100% specificity, 100% negative predictive value and 100% positive predictive value. Since the successful treatment of septicemia depends on prompt administration of the appropriate antimicrobial agents, use of the ESBL NDP test directly from positive blood cultures may significantly improve the outcome of infected patients.
http://dx.doi.org/10.1016/j.ijid.2014.03.1174 Type: Poster Presentation
Final Abstract Number: 59.013 Session: Diagnosis Date: Saturday, April 5,2014 Time: 12:45-14:15 Room: Ballroom
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A case of chronic meningitis caused by Cryptococcus neoformans, which was detected only with the use of mycobacterial blood culture bottle for cerebrospinal fluid
H. Matsuo, K. Iwata
Kobe University, Kobe, Hyogo, Japan
Background: Cryptococcus is known to cause chronic meningitis. Diagnosis is usually made with the use of cryptococcus antigen test of cerebrospinal fluid (CSF). Despite its high sensitivity, false negative result can occur, particularly then the amount of the organism in CSF was small. We herein report a case of cryptococcal meningitis in a non-HIV patient, with negative india ink, negative CSF cryptococcal antigen test, negative routine CSF fungal culture, and positive only with the use of mycobacterial blood culture bottle.
Methods & Materials: The patient is 38-year-old man without significant past medical history, who presented with gait instability for 40 days. He also complained of intermittent headache since 20 days prior to the first visit, which worsened gradually. He started to feel weak on his left lower extremity, and had difficulty in standings up. On physical examination, he was alert but disoriented. His neck was supple, but had gait instability. Head magnetic resonance imaging study only showed widening of lateral ventricles. Cere-brospinal fluid examination revealed opening pressure was 24.5 cmH2O, cell count 143/|Lwith87% polymorphonuclear cells, protein 184mg/dL, glucose 7 mg/dL, with negative Gram staining, acid fast bacilli staining, india ink staining, and cryptococcal antigen test.
Results: Cryptococcus neoformans var grubii was detected only from mycobacterial culture bottle 7 days later, despite negative routine fungal culture. He was treated with amphotericin B lipid complex and flucytosine, together with spinal drainage, followed by fluconazole maintenance therapy for 6 months. His neurological abnormalities improved without recurrence
Conclusion: Cryptococcal antigen test of CSF has high sensitivity for the diagnosis of meningitis, but false negative still can occur. Previous studies suggest that the use of mycobacterial blood culture bottle may increase the sensitivity of fungemia in general. There is no literature reporting the use of mycobacterial blood culture bottle for the diagnosis of cryptococcal meningitis. The use of it on CSF,
on top of conventional work up, may heighten the diagnostic yield of this infection.
http://dx.doi.org/10.1016Zj.ijid.2014.03.1175 Type: Poster Presentation
Final Abstract Number: 59.014 Session: Diagnosis Date: Saturday, April 5,2014 Time: 12:45-14:15 Room: Ballroom
Utilization of malaria diagnostic tests and receipt of anti-malarial drugs by febrile patients attending outpatient departments of health center IVs in Mukono district, Uganda
R. Naigino1, H. Babikako1, A. Katamba2, A. Mukose 2
1 Makerere University School of Public Health, Kampala, Uganda
2 Makerere University, Kampala, Uganda
Background: Failure to demonstrate the presence of malaria parasites prior to treatment with anti-malarial drugs remains a challenge in Uganda, often resulting into over-prescription of antimalarial drugs to febrile patients suspected of malaria. The aim of this study was to describe the role of utilization of malaria diagnostic tests and associated factors in the receipt of anti-malarial drugs among febrile patients suspected of malaria.
Methods & Materials: In a cross-sectional study design, client-exit interviews with febrile patients and key-informant interviews with purposively selected health workers were conducted at health center IVs in Mukono district. Data entry and analysis were done using Epi-Data 3.2 and STATA10 respectively. Data were described using frequency distributions and proportions. Chi square was used in two by two tables, odds ratios as the measure of association and an alpha level of 0.05 was used in all significance tests.
Results: Out of 408 respondents, 359 (88%) utilized malaria diagnostic tests and 241(59%) received antimalarial drugs. Majority were female 252 (61.8%) and a third of the sample was aged five years and below. There were no statistically significant differences between utilizers and non-utilizers in most characteristics except age, history of indoor residual spraying and satisfaction with services. Utilizers were 75% less likely to receive anti-malarial drugs than non-utilizers after controlling for age, sex and residence (OR: 0.25, 95%CI: 0.09, 0.66).
Power was the main limitation to microscopic diagnosis of malaria and laboratory personnel had limited knowledge on malaria treatment guidelines.
Conclusion: Utilizers were 75% less likely to receive anti-malarial drugs as opposed to non-utilizers. This implies that increasing utilization of malaria diagnostic tests can reduce the problem of overprescription of anti-malarial drugs by 75% among those tested for malaria, since antimalarial drugs will be received by only those with a parasitologically-confirmed diagnosis of malaria.
http://dx.doi.org/10.1016/j.ijid.2014.03.1176
