TY - JOUR A1 - Kohlmorgen, Britta A1 - Elias, Johannes A1 - Schoen, Christoph T1 - Improved performance of the artus Mycobacterium tuberculosis RG PCR kit in a low incidence setting: a retrospective monocentric study JF - Scientific Reports N2 - Tuberculosis (TB) and the spread of Mycobacterium tuberculosis complex (MTBC) strains resistant against rifampin (RIF) and isoniazid (INH) pose a serious threat to global health. However, rapid and reliable MTBC detection along with RIF/INH susceptibility testing are challenging in low prevalence countries due to the higher rate of false positives. Here, we provide the first performance data for the artus MTBC PCR assay in a low prevalence setting. We analyze 1323 respiratory and 311 non-respiratory samples with the artus MTBC PCR assay as well as by mycobacterial culture and microscopy. We propose retesting of specimens in duplicate and consideration of a determined cycle-threshold value cut-off greater than 34, as this significantly increases accuracy, specificity, and negative predictive value without affecting sensitivity. Furthermore, we tested fourteen MTBC positive samples with the GenoType MTBDRplus test and demonstrate that using an identical DNA extraction protocol for both assays does not impair downstream genotypic testing for RIF and INH susceptibility. In conclusion, our procedure optimizes the use of the artus MTB assay with workload efficient methods in a low incidence setting. Combining the modified artus MTB with the GenoType MTBDRplus assays allows rapid and accurate detection of MTBC and RIF/INH resistance. KW - laboratory techniques and procedures KW - Tuberculosis Y1 - 2017 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-159248 VL - 7 IS - 14127 ER - TY - JOUR A1 - Elias, Johannes A1 - Schouls, Leo M. A1 - van de Pol, Ingrid A1 - Keijzers, Wendy C. A1 - Martin, Diana R. A1 - Glennie, Anne A1 - Oster, Philipp A1 - Frosch, Matthias A1 - Vogel, Ulrich A1 - van der Ende, Arie T1 - Vaccine Preventability of Meningococcal Clone, Greater Aachen Region, Germany N2 - No abstract available KW - IMD Y1 - 2010 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-68083 ER - TY - JOUR A1 - Schoen, Christoph A1 - Kischkies, Laura A1 - Elias, Johannes A1 - Ampattu, Biju Joseph T1 - Metabolism and virulence in Neisseria meningitidis N2 - A longstanding question in infection biology addresses the genetic basis for invasive behavior in commensal pathogens. A prime example for such a pathogen is Neisseria meningitidis. On the one hand it is a harmless commensal bacterium exquisitely adapted to humans, and on the other hand it sometimes behaves like a ferocious pathogen causing potentially lethal disease such as sepsis and acute bacterial meningitis. Despite the lack of a classical repertoire of virulence genes in N. meningitidis separating commensal from invasive strains, molecular epidemiology suggests that carriage and invasive strains belong to genetically distinct populations. In recent years, it has become increasingly clear that metabolic adaptation enables meningococci to exploit host resources, supporting the concept of nutritional virulence as a crucial determinant of invasive capability. Here, we discuss the contribution of core metabolic pathways in the context of colonization and invasion with special emphasis on results from genome-wide surveys. The metabolism of lactate, the oxidative stress response, and, in particular, glutathione metabolism as well as the denitrification pathway provide examples of how meningococcal metabolism is intimately linked to pathogenesis. We further discuss evidence from genome-wide approaches regarding potential metabolic differences between strains from hyperinvasive and carriage lineages and present new data assessing in vitro growth differences of strains from these two populations. We hypothesize that strains from carriage and hyperinvasive lineages differ in the expression of regulatory genes involved particularly in stress responses and amino acid metabolism under infection conditions. KW - Neisseria meningitidis KW - virulence KW - pathometabolism KW - oxidative stress KW - glutathione KW - γ-glutamyl cycle KW - glutamate dehydrogenase KW - nitrite respiration Y1 - 2014 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-113118 ER - TY - JOUR A1 - Elias, Johannes A1 - Heuschmann, Peter U. A1 - Schmitt, Corinna A1 - Eckhardt, Frithjof A1 - Boehm, Hartmut A1 - Maier, Sebastian A1 - Kolb-Mäurer, Annette A1 - Riedmiller, Hubertus A1 - Müllges, Wolfgang A1 - Weisser, Christoph A1 - Wunder, Christian A1 - Frosch, Matthias A1 - Vogel, Ulrich T1 - Prevalence dependent calibration of a predictive model for nasal carriage of methicillin-resistant Staphylococcus aureus JF - BMC Infectious Diseases N2 - Background Published models predicting nasal colonization with Methicillin-resistant Staphylococcus aureus among hospital admissions predominantly focus on separation of carriers from non-carriers and are frequently evaluated using measures of discrimination. In contrast, accurate estimation of carriage probability, which may inform decisions regarding treatment and infection control, is rarely assessed. Furthermore, no published models adjust for MRSA prevalence. Methods Using logistic regression, a scoring system (values from 0 to 200) predicting nasal carriage of MRSA was created using a derivation cohort of 3091 individuals admitted to a European tertiary referral center between July 2007 and March 2008. The expected positive predictive value of a rapid diagnostic test (GeneOhm, Becton & Dickinson Co.) was modeled using non-linear regression according to score. Models were validated on a second cohort from the same hospital consisting of 2043 patients admitted between August 2008 and January 2012. Our suggested correction score for prevalence was proportional to the log-transformed odds ratio between cohorts. Calibration before and after correction, i.e. accurate classification into arbitrary strata, was assessed with the Hosmer-Lemeshow-Test. Results Treating culture as reference, the rapid diagnostic test had positive predictive values of 64.8% and 54.0% in derivation and internal validation corhorts with prevalences of 2.3% and 1.7%, respectively. In addition to low prevalence, low positive predictive values were due to high proportion (> 66%) of mecA-negative Staphylococcus aureus among false positive results. Age, nursing home residence, admission through the medical emergency department, and ICD-10-GM admission diagnoses starting with “A” or “J” were associated with MRSA carriage and were thus included in the scoring system, which showed good calibration in predicting probability of carriage and the rapid diagnostic test’s expected positive predictive value. Calibration for both probability of carriage and expected positive predictive value in the internal validation cohort was improved by applying the correction score. Conclusions Given a set of patient parameters, the presented models accurately predict a) probability of nasal carriage of MRSA and b) a rapid diagnostic test’s expected positive predictive value. While the former can inform decisions regarding empiric antibiotic treatment and infection control, the latter can influence choice of screening method. KW - Methicillin-resistant staphylococcus aureus KW - Infection control KW - Clinical prediction rule KW - Predictive value of tests KW - False positive reactions KW - Calibration Y1 - 2013 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-96091 UR - http://www.biomedcentral.com/1471-2334/13/111 ER - TY - JOUR A1 - Elias, Johannes A1 - Findlow, Jamie A1 - Borrow, Ray A1 - Tremmel, Angelika A1 - Frosch, Matthias A1 - Vogel, Ulrich T1 - Persistence of antibodies in laboratory staff immunized with quadrivalent meningococcal polysaccharide vaccine JF - Journal of Occupational Medicine and Toxicology N2 - Background Occupational exposure to live meningococci can potentially cause invasive meningococcal disease in laboratory staff. While, until recently, immunization with quadrivalent polysaccharide vaccine represented one cornerstone of protection, data on long-term persistence of antibodies in adults remain scarce. Methods We analyzed the relationship of antibody levels and time following quadrivalent polysaccharide vaccination (Mencevax® ACWY, GlaxoSmithKline) in a cross-sectional sample of 20 laboratory workers vaccinated at ages between 16.4 to 40.7 years from Germany. Sera were obtained 0.4 to 158.5 (median 35.3) months after vaccination. At the time of sampling, laboratory workers had been regularly exposed to meningococci for periods between 3.2 to 163.8 (median 41.2) months. Serum bactericidal assay (SBA) with rabbit complement and a microsphere-based flow analysis method were used to determine bactericidal titers and concentrations of IgG, respectively, against serogroups A, C, W135, and Y. Decay of antibodies was modeled using linear regression. Protective levels were defined as SBA titers ≥ 8. Results Half-lives of SBA titers against serogroups A, C, W135, and Y were estimated at 27.4, 21.9, 18.8, and 28.0 months, respectively. Average durations of protection were estimated at 183.9, 182.0, 114.6, and 216.4 months, respectively. Inter-individual variation was high; using lower margins of 95% prediction intervals, minimal durations of protection against serogroups A, C, W135 and Y were estimated at 33.5, 24.6, 0.0, and 55.1 months, respectively. The proportion of staff with protective SBA titers against W135 (65.0%) was significantly lower than proportions protected against A (95.0%), C (94.7%), and Y (95.0%). Consistently, geometric mean titer (97.0) and geometric mean concentration of IgG (2.1 μg/ml) was lowest against serogroup W135. SBA titers in a subset of individuals with incomplete protection rose to ≥ 128 (≥ 8 fold) after reimmunization with a quadrivalent glycoconjugate vaccine. Conclusions The average duration of protection following immunization with a quadrivalent polysaccharide vaccine in adults was ≥ 115 months regardless of serogroup. A substantial proportion (approximately 23% according to our decay model) of adult vaccinees may not retain protection against serogroup W135 for five years, the time suggested for reimmunization. KW - Vaccination KW - Meningococcal infection KW - Biohazard KW - Meningococcal polysaccharide caccine Y1 - 2013 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-95953 UR - http://www.occup-med.com/content/8/1/4 ER -