Simultaneous single-tube PCR-based assay for the direct identification of the five most common meningococcal serogroups from clinical samples

This study presents a stepdown multiplex PCR assay for the simultaneous detection of the five most common Neisseria meningitidis serogroups (A, B, C, W-135 and Y) in 530 clinical samples obtained from 428 patients (271 blood and 259 cerebrospinal fluid). The sensitivity and the specificity was calculated to 100% [positive predictive value 100% (95%, CI 99.0-100%) and negative predictive value 100% (95% CI 99.0-100%)]. The overall effectiveness permits the rapid, accurate and inexpensive detection of the five most prevalent meningococcal serogroups in clinical samples. It is potentially a valuable tool for diagnosis and epidemiological monitoring of disease due to N. meningitidis.     

Diagnosis of Streptococcus pneumoniae meningitis by polymerase chain reaction amplification of the gene for pneumolysin

Diagnosis of bacterial meningitis has long been based on classical methods of Gram stain, serological tests, and culture of cerebrospinal fluid (CSF). The performance of these methods, especially culture and direct smear is thwarted by failure to detect bacteria following administration of antimicrobial agents and reluctance to performance lumbar punctures at admission. Indeed, patients with meningitis frequently receive antibiotics orally or by injection before the diagnosis is suspected or established Thus an alternative method has become necessary to help clinicians and epidemiologists to management and control of bacterial meningitis. We evaluate the application of a polymerase chain reaction-based (PCR) assay for amplification of pneumolysin gene (ply) to diagnosis of Streptococcus pneumoniae meningitis. The PCR assay sensitivity for CSF was 96% (95% confidence interval, CI, 90-99%) compared to a sensitivity of 59% for culture (95% CI 49-69%), 66% for Gram stain (95% CI 56-74%), and 78% for latex agglutination test (95% CI 69-86%); PCR specificity was 100% (95% CI 83-100%). PCR results were available within 4 h of the start of the assay. This molecular approach proved to be reliable and useful to identify this bacterium compared with other classical laboratory methods for identification of bacterial meningitis pathogens.     

Evaluation of the Applied Biosystems automated Taqman polymerase chain reaction system for the detection of meningococcal DNA

In a period where the proportion of culture confirmed cases in the UK has been steadily declining, diagnosis by PCR has been used to increase the number of confirmed cases and provide additional epidemiological data. This report presents a comparative evaluation of the fluorogenic probe-based 5' exonuclease assay (Taqman) using the Perkin-Elmer Applied Biosystems automated sequence detection system 7700 with previously reported polymerase chain reaction enzyme-linked immunosorbent (PCR ELISA) assays for the detection of meningococcal DNA in CSF, plasma and serum samples. Taqman assays developed were based on the detection of a meningococcal capsular transfer gene (ctrA), the insertion sequence IS1106 and the sialytransferase gene (siaD) for serogroup B and C determination and compared with similar assays in a PCR ELISA format. The Taqman ctrA assay was specific for Neisseria meningitidis, however the IS1106 assay gave false positive reactions with a number of non-meningococcal isolates. Sensitivity of the Taqman ctrA, IS1106 and siaD assays testing samples from culture-confirmed cases were 64, 69 and 50%, respectively, compared with 26, 67 and 43% for the corresponding PCR ELISA assays. Improvements to the DNA extraction procedure has increased the sensitivity to 93 and 91% for the TaqMan ctrA and siaD assays, respectively, compared to culture confirmed cases. Since the introduction of Taqman PCR a 56% increase in laboratory confirmed cases of meningococcal disease has been observed compared to culture only confirmed cases. The developed Taqman assays for the diagnosis of meningococcal disease enables a high throughput, rapid turnaround of samples with considerable reduced risk of contamination.     

Evaluation of touch-down real-time PCR based on SYBR Green I fluorescent dye for the detection of Neisseria meningitidis in clinical samples

Antibiotic treatment prior to transport or admission of patients to hospital has reduced the proportion of patients with invasive meningococcal disease (IMD) from whom Neisseria meningitidis can be isolated by standard microbiological techniques. Assays to detect the crgA gene were used to detect meningococcal DNA by both conventional polymerase chain reaction (PCR) and real-time PCR (RTPCR) in relation to microbiological diagnosis of cases over two years between 2002 and 2003. The sensitivity of both PCR assays for culture-confirmed cases was 93% and the specificity was 98.6%. Agreement between the two PCR assays was 96.2%. The inter- and intra-assay variations and effects of different amounts of DNA on the melting temperatures were examined. The touch-down RTPCR based on SYBR Green I fluorescent dye detected and characterized N. meningitidis in clinical samples within one hour.     

Evaluation of non-culture diagnosis of invasive meningococcal disease by polymerase chain reaction (PCR)

Antibiotic treatment prior to transport or admission to hospital has reduced the proportion of cases of invasive meningococcal disease (IMD) from which Neisseria meningitidis can be isolated by standard microbiological techniques. Identification of meningococci by polymerase chain reaction (PCR) was assessed in relation to microbiological diagnosis for cases over a 4-year period between 1998 and 2001. A screening assay for the IS1106 gene was used to detect meningococcal DNA and five additional assays for siaD and orf-2 genes were performed to determine the serogroup. PCR results were compared with results of bacteriological culture, other laboratory test results and clinical data. The sensitivity of the PCR assay for culture-confirmed cases was 98.5%. The specificity of the assay was 96% based on test results for patients from whom other bacteria were isolated, children with viral meningitis and afebrile negative controls. The siaD B/C/W-135 and Y as well as the orf-2 gene for serogroup A PCR assays were able to determine the serogroup for 75.2% of cases that were positive by PCR screening assay. When isolates from patients with IMD were tested by both agglutination and PCR, the results agreed in all cases. PCR is a useful tool for diagnosis of IMD when Gram stain and culture tests are negative due to antibiotic treatment prior to collection of samples for microbiological analyses.     

Incorporation of real-time PCR into routine public health surveillance of culture negative bacterial meningitis in São Paulo, Brazil

Real-time (RT)-PCR increases diagnostic yield for bacterial meningitis and is ideal for incorporation into routine surveillance in a developing country. We validated a multiplex RT-PCR assay for Streptococcus pneumoniae, Neisseria meningitidis, and Haemophilus influenzae in Brazil. Risk factors for being culture-negative, RT-PCR positive were determined. The sensitivity of RT-PCR in cerebrospinal fluid (CSF) was 100% (95% confidence limits, 96.0%-100%) for N. meningitidis, 97.8% (85.5%-99.9%) for S. pneumoniae, and 66.7% (9.4%-99.2%) for H. influenzae. Specificity ranged from 98.9% to 100%. Addition of RT-PCR to routine microbiologic methods increased the yield for detection of S. pneumoniae, N. meningitidis, and H. influenzae cases by 52%, 85%, and 20%, respectively. The main risk factor for being culture negative and RT-PCR positive was presence of antibiotic in CSF (odds ratio 12.2, 95% CI 5.9-25.0). RT-PCR using CSF was highly sensitive and specific and substantially added to measures of meningitis disease burden when incorporated into routine public health surveillance in Brazil.     

Direct PCR assay for detection ofNeisseria meningitidis in human cerebrospinal fluid

A PCR amplification was performed to detectNeisseria meningitidis insertion sequence1106 (IS-1106) in the humancerebrospinalfluid (CSF) in cases of meningitis. The study included 27 CSF samples from suspected meningitis patients. Although the inflammatory response in most of the samples was slightly increased, the results showed that 7 (26%) and 8 (30%) CSF samples were diagnosed as meningococcal meningitis by Gram staining and by culture, respectively. The primers of theIS-1106 were used for direct diagnosis ofN. meningitidis in the human spinal fluid after a minor treatment of the CSF samples. The sample was diagnosed as meningococcal meningitis, if a DNA band of about 600 bp was detected in the ethidium bromide-stained agarose gel. The 27 CSF samples were analyzed in a random manner. Of these, 18 samples including the Gram staining- and culture-positive samples were also positive in PCR amplification. However, a CSF sample, which was diagnosed to be meningococcal meningitis in culture was negative in both Gram staining and PCR analysis. The specificity of theIS-1106 primers was determined to be 95%, with 100% sensitivity in comparison to Gram staining and culture. The primers were sensitive to 10 pg or more of meningococcal DNA. In addition, the PCR amplification showed high predictive values (89 and 100%) in diagnosing meningitis in patients that were negative and positive responders when tested by culture and by Gram staining. In conclusion, the PCR amplification ofIS-1106 ofN. meningitidis is specific and sensitive to both culture-positive and-negative meningococcal meningitis. Hence, PCR assay is highly recommended for use in a rapid diagnosis of suspected meningitis patients.     

The prospects for the diagnosis of bacterial meningitis]

The samples of spinal fluid arriving to the Clinical Infectious Hospital in 1994-1996 with the clinical diagnosis "generalized form of meningococcal infection" or "purulent meningitis of unclear etiology" were studied. The etiological agent was bacteriologically identified in 35% of 487 patients (in 25% of cases Neisseria meningitidis, in 7% of cases Streptococcus pneumoniae and in 2% of cases Haemophilus influenzae, type b, were detected). The method of latex agglutination, used in this study, was highly specific (100%) and moderately sensitive (67%); this method made it possible to diagnose 25% of cases additionally (N. meningitidis in 15% of cases, S. pneumoniae in 5% of cases and H. influenzae in 3% of cases). Diagnostics with the use of PCR was characterized by high specificity (> 97%) and sensitivity (> 85%) relatively to the "golden standard" of microbiological diagnostics. There were few false positive results (3 samples), caused probably by contamination at the moment of taking the samples. For this reason the results obtained by PCR could be used for diagnostic purposes even in cases of negative results given by other methods. Tests with the use of PCR made it possible to diagnose 29% more cases additionally (in 26% of cases N. meningitidis DNA and in 3% of cases S. pneumoniae DNA were detected. Thus the complex of methods used in this study permitted the detection of the etiological agent altogether in 87% of cases.     

Field Evaluation of Two Rapid Diagnostic Tests for Neisseria meningitidis Serogroup A during the 2006 Outbreak in Niger

The Pastorex^® (BioRad) rapid agglutination test is one of the main rapid diagnostic tests (RDTs) for meningococcal disease currently in use in the “meningitis belt”. Earlier evaluations, performed after heating and centrifugation of cerebrospinal fluid (CSF) samples, under good laboratory conditions, showed high sensitivity and specificity. However, during an epidemic, the test may be used without prior sample preparation. Recently a new, easy-to-use dipstick RDT for meningococcal disease detection on CSF was developed by the Centre de Recherche Médicale et Sanitaire in Niger and the Pasteur Institute in France. We estimate diagnostic accuracy in the field during the 2006 outbreak of Neisseria meningitidis serogroup A in Maradi, Niger, for the dipstick RDT and Pastorex^® on unprepared CSF, (a) by comparing each test''s sensitivity and specificity with previously reported values; and (b) by comparing results for each test on paired samples, using McNemar''s test. We also (c) estimate diagnostic accuracy of the dipstick RDT on diluted whole blood. We tested unprepared CSF and diluted whole blood from 126 patients with suspected meningococcal disease presenting at four health posts. (a) Pastorex^® sensitivity (69%; 95%CI 57–79) was significantly lower than found previously for prepared CSF samples [87% (81–91); or 88% (85–91)], as was specificity [81% (95%CI 68–91) vs 93% (90–95); or 93% (87–96)]. Sensitivity of the dipstick RDT [89% (95%CI 80–95)] was similar to previously reported values for ideal laboratory conditions [89% (84–93) and 94% (90–96)]. Specificity, at 62% (95%CI 48–75), was significantly lower than found previously [94% (92–96) and 97% (94–99)]. (b) McNemar''s test for the dipstick RDT vs Pastorex^® was statistically significant (p<0.001). (c) The dipstick RDT did not perform satisfactorily on diluted whole blood (sensitivity 73%; specificity 57%).Sensitivity and specificity of Pastorex^® without prior CSF preparation were poorer than previously reported results from prepared samples; therefore we caution against using this test during an epidemic if sample preparation is not possible. For the dipstick RDT, sensitivity was similar to, while specificity was not as high as previously reported during a more stable context. Further studies are needed to evaluate its field performance, especially for different populations and other serogroups.     

Rapid molecular identification of Neisseria meningitidis isolates using the polymerase chain reaction followed by single-stranded conformation polymorphism analysis

Typing of Neisseria meningitidis strains is currently performed with conventional and molecular methods. Our objectives were: first, to develop a polymerase chain reaction (PCR) followed by single-stranded conformation polymorphism (SSCP) analysis of the PorA gene (VR1 region) to distinguish N. meningitidis subtypes and second, to evaluate the method for the identification and characterization of N. meningitidis in patient specimens. SSCP analysis of the VR1 region of the PorA1/2 gene from 126 N. meningitidis strains and 29 clinical samples identified seven SSCP types (SP-1 to SP-7); four strains were not typeable by the method. Classification according to the SSCP methods and serosubtype agreed for 122 of the 126 typeable strains (96.8%). For the 24-culture positive clinical samples, serosubtype and SSCP agreed in all cases. Five samples, which were culture-negative but obtained from children during an apparent outbreak of meningococcal disease in a primary school, presented identical SSCP classification for each sample (SP-2). PCR-SSCP is a rapid and cost-effective method for typing N. meningitidis strains that could provide important early information in the surveillance of suspected meningococcal outbreaks, particularly when culture-negative specimens constitutes the main source of material to analyze.     

Evaluation of the antiserum agar method for the serogroup identification of Neisseria meningitidis.

The antiserum agar method (ASA), which is based on the formation of immunoprecipitates around bacterial growth on agar containing meningococcal hyperimmune horse serum, was evaluated for serogroup identification of Neisseria meningitidis. Four hundred meningococcal stains were serogrouped by ASA employing horse antisera to serogroups A, B, C, Y, W135, Z, and 29E and compared to serogroup identification by bacterial slide agglutination (BA) employing rabbit antisera. Overall, there was 95% agreement between the two methods. The ASA proved to be more accurate than BA since 15 strains which cross-reacted with Y and W135 rabbit antisera by BA were specifically serogrouped as either Y or W135 by ASA. In addition, 5 out of 75 strains which were ungroupable by BA were serogrouped as either B or 29E by ASA. Repeat serogroup identification of 100 meningococcal strains by ASA provided identical results thus showing the reproducibility of the method. The ASA is advantageous to BA since it is more reliable, utilizes standard antisera which do not have to be absorbed to remove cross-reactions, does not require the preparation of standardized bacterial antigen, and is simple to perform.     

Invasive meningococcal disease and latex agglutination test — Is it still beneficial for diagnosis?

We showed current clinical usefulness of the latex agglutination (LA) test for confirmation of meningococcal etiology on 32 cerebrospinal fluid, 77 serum and 93 urine samples collected during the first week of hospitalization from 19 patients with laboratory confirmed invasive meningococcal disease. The positivity of the LA test in cerebrospinal fluid was 47%, in serum 42% and in urine 24%, while the PCR of cerebrospinal fluid and serum was positive in 95 and 47% cases, respectively. The latest positivity of the LA test was detected on day 2 in cerebrospinal fluid, on day 3 in serum and on day 4 in urine. In the group of patients who had received antibiotic therapy we found nonsignificant reduction of LA positivity and also statistically significant reduction of culture positivity in CSF (p = 0.04); the PCR positivity changed minimally. In blood samples, nonsignificant reduction of culture positivity and no difference in LA and PCR positivity was found. We did not find any statistically significant relationship between test results and clinical forms. The LA test can be therefore considered to be an auxiliary diagnostic method, rapid and easily practicable but less sensitive than PCR. It can be recommended especially for local laboratories where PCR is not available and the patient already received antibiotics before admission to the hospital.     

An Optimized Immunohistochemistry Technique Improves NMO-IgG Detection: Study Comparison with Cell-Based Assays

Cell-based assays (CBA) have increased the sensitivity of the neuromyelitis optica (NMO)-IgG/aquaporin-4-antibody detection compared to classical tissue-based indirect assays. We describe the sensitivity of an optimized immunohistochemistry (IHC-o) to detect NMO-IgG/aquaporin-4-antibody in comparison with that of two CBA: an in-house (CBA-ih) and a commercial (CBA-c) assay (Euroimmun, Germany). Coded serum from 103 patients with definite NMO and 122 inflammatory controls were studied by IHC-o, CBA-ih, and CBA-c. IHC-o used the same protocol described to detect antibodies against cell surface antigens. CBA-ih used live cells transfected with the aquaporin-4-M23-isoform. The sensitivity of the IHC-o was 74.8% (95% confidence interval [CI] 65-83) and was similar to that of the CBA-ih 75.7% (95% CI 66-84) and the CBA-c 73.8% (95% CI 64-82). The specificity of the three assays was 100% (95% CI 97-100). Interassay concordance was high, 100 of 103 samples were coincident in all techniques. The optimized immunohistochemistry proves to be as sensitive and specific as the cell-based assays. This assay extends the available tools for NMO-IgG/aquaporin-4-antibody detection.     

Meningitis Dipstick Rapid Test: Evaluating Diagnostic Performance during an Urban Neisseria meningitidis Serogroup A Outbreak,Burkina Faso, 2007

Meningococcal meningitis outbreaks occur every year during the dry season in the “meningitis belt” of sub-Saharan Africa. Identification of the causative strain is crucial before launching mass vaccination campaigns, to assure use of the correct vaccine. Rapid agglutination (latex) tests are most commonly available in district-level laboratories at the beginning of the epidemic season; limitations include a short shelf-life and the need for refrigeration and good technical skills. Recently, a new dipstick rapid diagnostic test (RDT) was developed to identify and differentiate disease caused by meningococcal serogroups A, W135, C and Y. We evaluated the diagnostic performance of this dipstick RDT during an urban outbreak of meningitis caused by N. meningitidis serogroup A in Ouagadougou, Burkina Faso; first against an in-country reference standard of culture and/or multiplex PCR; and second against culture and/or a highly sensitive nested PCR technique performed in Oslo, Norway. We included 267 patients with suspected acute bacterial meningitis. Using the in-country reference standard, 50 samples (19%) were positive. Dipstick RDT sensitivity (N = 265) was 70% (95%CI 55–82) and specificity 97% (95%CI 93–99). Using culture and/or nested PCR, 126/259 (49%) samples were positive; dipstick RDT sensitivity (N = 257) was 32% (95%CI 24–41), and specificity was 99% (95%CI 95–100). We found dipstick RDT sensitivity lower than values reported from (i) assessments under ideal laboratory conditions (>90%), and (ii) a prior field evaluation in Niger [89% (95%CI 80–95)]. Specificity, however, was similar to (i), and higher than (ii) [62% (95%CI 48–75)]. At this stage in development, therefore, other tests (e.g., latex) might be preferred for use in peripheral health centres. We highlight the value of field evaluations for new diagnostic tests, and note relatively low sensitivity of a reference standard using multiplex vs. nested PCR. Although the former is the current standard for bacterial meningitis surveillance in the meningitis belt, nested PCR performed in a certified laboratory should be used as an absolute reference when evaluating new diagnostic tests.     

Improved antiserum agar method for the serogroup differentiation of Neisseria meningitidis Y and W135

Rabbit antisera prepared to meningococcal serogroups Y and W135 strains were compared with horse antisera using the antiserum agar method (ASA) for the serogroup identification of Neisseria meningitidis. Thirty-seven group Y strains formed immunoprecipitates with the Y rabbit serum only, whereas the same Y strains formed immunoprecipitates with both the Y and W135 horse antisera. Forty-seven W135 strains formed specific immunoprecipitates with both the rabbit and horse W135 antisera by ASA. None of the 166 meningococcal isolates, representative of other meningococcal serogroups, formed immunoprecipitates with the groups Y and W135 rabbit or horse antisera. Use of specific Y and W135 rabbit antisera in ASA provides an improved technique for the serogroup differentiation of groups Y and W135 meningococci.     

sodC-based real-time PCR for detection of Neisseria meningitidis

Real-time PCR (rt-PCR) is a widely used molecular method for detection of Neisseria meningitidis (Nm). Several rt-PCR assays for Nm target the capsule transport gene, ctrA. However, over 16% of meningococcal carriage isolates lack ctrA, rendering this target gene ineffective at identification of this sub-population of meningococcal isolates. The Cu-Zn superoxide dismutase gene, sodC, is found in Nm but not in other Neisseria species. To better identify Nm, regardless of capsule genotype or expression status, a sodC-based TaqMan rt-PCR assay was developed and validated. Standard curves revealed an average lower limit of detection of 73 genomes per reaction at cycle threshold (C(t)) value of 35, with 100% average reaction efficiency and an average R(2) of 0.9925. 99.7% (624/626) of Nm isolates tested were sodC-positive, with a range of average C(t) values from 13.0 to 29.5. The mean sodC C(t) value of these Nm isolates was 17.6±2.2 (±SD). Of the 626 Nm tested, 178 were nongroupable (NG) ctrA-negative Nm isolates, and 98.9% (176/178) of these were detected by sodC rt-PCR. The assay was 100% specific, with all 244 non-Nm isolates testing negative. Of 157 clinical specimens tested, sodC detected 25/157 Nm or 4 additional specimens compared to ctrA and 24 more than culture. Among 582 carriage specimens, sodC detected Nm in 1 more than ctrA and in 4 more than culture. This sodC rt-PCR assay is a highly sensitive and specific method for detection of Nm, especially in carriage studies where many meningococcal isolates lack capsule genes.     

Genetic variation in the β2-adrenocepter gene is associated with susceptibility to bacterial meningitis in adults

Recently, the biased β2-adrenoceptor/β-arrestin pathway was shown to play a pivotal role in crossing of the blood brain barrier by Neisseria meningitidis. We hypothesized that genetic variation in the β2-adrenoceptor gene (ADRB2) may influence susceptibility to bacterial meningitis. In a prospective genetic association study we genotyped 542 patients with CSF culture proven community acquired bacterial meningitis and 376 matched controls for 2 functional single nucleotide polymorphisms in the β2-adrenoceptor gene (ADRB2). Furthermore, we analyzed if the use of non-selective beta-blockers, which bind to the β2-adrenoceptor, influenced the risk of bacterial meningitis. We identified a functional polymorphism in ADRB2 (rs1042714) to be associated with an increased risk for bacterial meningitis (Odds ratio [OR] 1.35, 95% confidence interval [CI] 1.04-1.76; p?=?0.026). The association remained significant after correction for age and was more prominent in patients with pneumococcal meningitis (OR 1.52, 95% CI 1.12-2.07; p?=?0.007). For meningococcal meningitis the difference in genotype frequencies between patients and controls was similar to that in pneumococcal meningitis, but this was not statistically significant (OR 1.43, 95% CI 0.60-3.38; p?=?0.72). Patients with bacterial meningitis had a lower frequency of non-selective beta-blockers use compared to the age matched population (0.9% vs. 1.8%), although this did not reach statistical significance (OR 1.96 [95% CI 0.88-4.39]; p?=?0.09). In conclusion, we identified an association between a genetic variant in the β2-adrenoceptor and increased susceptibility to bacterial meningitis. The potential benefit of pharmacological treatment targeting the β2-adrenoceptor to prevent bacterial meningitis in the general population or patients with bacteraemia should be further studied in both experimental studies and observational cohorts.     

Identification of two major families of transferrin receptors among Neisseria meningitidis strains based on antigenic and genomic features

Abstract The transferrin receptor or transferrin-binding proteins (Tbps) of 50 strains of Neisseria meningitidis belonging to different serogroups were examined by Western blotting using two rabbit antisera raised against Tbp purified from N. meningitidis strains B16B6 and M982. On the basis of the reactivity of Tbp2 with the antisera two patterns were observed and allowed the classification of 74% of the strains in group I (M982-like strains) and 26% in group II (B16B6-like strains). Southern blot analysis was performed on the genomic DNA of 16 meningococcal strains and showed that under stringent conditions, the tbp2 probes were specific for each group identified. Both immunological and genomic analyses have led to the identification within N. meningitidis strains of two major families distinguished on the basis of the characteristics of Tbp2 molecules, independently of serogroup, type or subtype.     

Clinical Evaluation of a Loop-Mediated Isothermal Amplification (LAMP) Assay for Rapid Detection of Neisseria meningitidis in Cerebrospinal Fluid

BackgroundNeisseria meningitidis (Nm) is a leading causative agent of bacterial meningitis in humans. Traditionally, meningococcal meningitis has been diagnosed by bacterial culture. However, isolation of bacteria from patients’ cerebrospinal fluid (CSF) is time consuming and sometimes yields negative results. Recently, polymerase chain reaction (PCR)-based diagnostic methods of detecting Nm have been considered the gold standard because of their superior sensitivity and specificity compared with culture. In this study, we developed a loop-mediated isothermal amplification (LAMP) method and evaluated its ability to detect Nm in cerebrospinal fluid (CSF).Conclusions/SignificanceCompared to PCR, LAMP detected Nm with higher analytical and clinical sensitivity. This sensitive and specific LAMP method offers significant advantages for screening patients on a population basis and for diagnosis in clinical settings.     

Use of the paired samples (cerebrospinal fluid and serum) in immunodiagnostic of active and inactive human neurocysticercosis

Paired samples of cerebrospinal fluid (CSF) and serum of 30 patients--10 with active, 10 with inactive neurocysticercosis (NCC), and 10 control subjects--were evaluated by enzyme-linked immunosorbent assay (ELISA) using two Taenia crassiceps metacestode extracts as antigen in order to detect IgG antibodies. In active NCC, high levels of IgG were detected (p < 0.05). The CSF samples showed 80% (CI 72-88) of reactivity in the saline extract (S) and 90% (CI 84-95) in sodium dodecyl sulphate (SDS) and the serum samples were reactive in 90% (CI 84-95) and 100% (CI 98-100) in the S and SDS antigenic extracts, respectively. The use of the paired samples of CSF and serum in active NCC showed equivalent results suggesting that the serum samples could be used as a screening in those patients whose CSF puncture is counter-indicated.