Authors:Michael Fehlings, Lea Drobbe, Macarena Beigier-Bompadre, Pablo Renner Viveros, Verena Moos, Thomas Schneider, Thomas F. Meyer, Toni Aebischer, and Ralf Ignatius
Direct effects of Helicobacter pylori (H. pylori) on human CD4+ T-cells hamper disentangling a possible bacterial-mediated interference with major histocompatibility complex class II (MHC-II)-dependent antigen presentation to these cells. To overcome this limitation, we employed a previously described assay, which enables assessing human antigen-processing cell function by using murine T-cell hybridoma cells restricted by human leukocyte antigen (HLA) alleles. HLA-DR1+ monocyte-derived dendritic cells were exposed to H. pylori and pulsed with the antigen 85B from Mycobacterium tuberculosis (M. tuberculosis). Interleukin-2 (IL-2) secretion by AG85Baa97-112-specific hybridoma cells was then evaluated as an integral reporter of cognate antigen presentation. This methodology enabled revealing of interference of H. pylori with the antigen-presenting capacity of human dendritic cells.
Authors:Norah Lynn-Anne Mund, Wycliffe Omurwa Masanta, Anne-Marie Goldschmidt, Raimond Lugert, Uwe Groß, and Andreas E. Zautner
Campylobacter jejuni’s flagellar locomotion is controlled by eleven chemoreceptors. Assessment of the distribution of the relevant chemoreceptor genes in the C. jejuni genomes deposited in the National Center for Biotechnology Information (NCBI) database led to the identification of two previously unknown tlp genes and a tlp5 pseudogene. These two chemoreceptor genes share the same locus in the C. jejuni genome with tlp4 and tlp11, but the gene region encoding the periplasmic ligand binding domain differs significantly from other chemoreceptor genes. Hence, they were named tlp12 and tlp13.
Consequently, it was of interest to study their distribution in C. jejuni subpopulations of different clonality, and their cooccurrence with the eleven previously reported chemoreceptor genes. Therefore, the presence of all tlp genes was detected by polymerase chain reaction (PCR) in 292 multilocus sequence typing (MLST)-typed C. jejuni isolates from different hosts.
The findings show interesting trends: Tlp4, tlp11, tlp12, and tlp13 appeared to be mutually exclusive and cooccur in a minor subset of isolates. Tlp4 was found to be present in only 33.56% of all tested isolates and was significantly less often detected in turkey isolates. Tlp11 was tested positive in only 17.8% of the isolates, while tlp12 was detected in 29.5% of all isolates, and tlp13 was found to be present in 38.7%.
Authors:Tobias Wiedemann, Stefan Hofbaur, Eva Loell, and Gabriele Rieder
Interleukin-8 (IL-8) is a potent neutrophil-activating chemokine which triggers the infiltration and migration of neutrophils into areas of bacterial infection. Helicobacter pylori-infected patient studies as well as animal models have revealed that H. pylori type I strains carrying an intact cytotoxin-associated gene pathogenicity island (cag-PAI) with a functional type IV secretion system (T4SS) induce IL-8 expression and secretion in gastric mucosa. This gastric mucosal IL-8 expression correlates with severe histological changes due to H. pylori infection.
In the present study, we explored a new recognition pattern on the bacterial adhesion protein CagL inducing IL-8 expression in H. pylori-infected host cells. To analyze the secreted IL-8 concentration, we performed IL-8 enzyme-linked immunosorbent assay (ELISA). To investigate the H. pylori-induced IL-8 expression on the transcriptional level, we transiently transfected gastric epithelial cells (AGS) with a human IL-8 luciferase reporter construct.
The results of this study demonstrate that specifically the C-terminal coiled-coil region of the H. pylori CagL protein, a protein described to be located on the tip of the T4SS-pilus, is responsible for several in vitro observations: 1) H. pylori-induced IL-8 secretion via the transforming growth factor (TGF)-α activated epidermal growth factor-receptor (EGF-R) signaling pathway; 2) H. pylori-induced elongation of the cells, a typical CagA-induced phenotype; and 3) the bridging of the T4SS to its human target cells. This novel bacterial-host recognition sequence allows a new insight into how H. pylori induces the inflammatory response in gastric epithelial cells and facilitates the development of precancerous conditions.
Authors:Sonja Obersteller, Heinrich Neubauer, Ralf Matthias Hagen, and Hagen Frickmann
The extraction and further processing of nucleic acids (NA) from formalin-fixed paraffin-embedded (FFPE) tissues for microbiological diagnostic polymerase chain reaction (PCR) approaches is challenging. Here, we assessed the effects of five different commercially available nucleic acid extraction kits on the results of real-time PCR.
FFPE samples from organs of Burkholderia pseudomallei-infected Swiss mice were subjected to processing with five different extraction kits from QIAGEN (FFPE DNA Tissue Kit, EZ1 DNA Tissue Kit, DNA Mini Kit, DNA Blood Mini Kit, and FlexiGene DNA Kit) in combination with three different real-time PCRs targeting B. pseudomallei-specific sequences of varying length after 16 years of storage.
The EZ1 DNA Tissue Kit and the DNA Mini Kit scored best regarding the numbers of successful PCR reactions. In case of positive PCR, differences regarding the cycle-threshold (Ct) values were marginal.
The impact of the applied extraction kits on the reliability of PCR from FFPE material seems to be low. Interfering factors like the quality of the dewaxing procedure or the sample age appear more important than the selection of specialized FFPE kits.
A century ago, Alfred Nissle discovered that intentional intake of particular strains of Escherichia coli could treat patients suffering from infectious diseases. Since then, one of these strains became the most frequently used probiotic E. coli in research and was applied to a variety of human conditions. Here, properties of that E. coli Nissle 1917 strain are compared with other commercially available E. coli probiotic strains, with emphasis on their human applications. A literature search formed the basis of a summary of research findings reported for the probiotics Mutaflor, Symbioflor 2, and Colinfant. The closest relatives of the strains in these products are presented, and their genetic content, including the presence of virulence, genes is discussed. A similarity to pathogenic strains causing urinary tract infections is noticeable. Historic trends in research of probiotics treatment for particular human conditions are identified. The future of probiotic E. coli may lay in what Alfred Nissle originally discovered: to treat gastrointestinal infections, which nowadays are often caused by antibiotic-resistant pathogens.
Authors:Orsolya Benedek, Andreas Podbielski, and Philipp Warnke
Chemiluminescent or enzyme-linked fluorescent immunoassays are commonly used to diagnose Clostridium difficile-associated diarrhea.
The LIAISON analyzer (DiaSorin, Italy) was compared to miniVIDAS (bioMérieux, France) and, furthermore, to culture of toxigenic strains. In total, 249 native stool samples were analyzed. Sensitivities, specificities, and positive and negative predictive values were investigated. Furthermore, performance under routine conditions was assessed.
The glutamate dehydrogenase chemiluminescent immunoassay (GDH-CLIA) assay revealed a high sensitivity and negative predictive value. The toxins A&B assays exhibited approximately the same low sensitivity and high specificity. Technical drawbacks experienced with the LIAISON analyzer in 48% of the analyses considerably delayed the time to the first diagnostic report and interfered with laboratory routine workflow.
The analytical performance of the investigated platforms should be reflected in the context of implementation into the laboratory workflow.
Authors:Magda Yehia El Seify, Eman Mahmoud Fouda, Hanan Mohamed Ibrahim, Maha Muhammad Fathy, Asmaa Al Husseiny Ahmed, Walaa Shawky Khater, Noha Nagi Mohammed Salah El Deen, Heba Galal Mohamed Abouzeid, Nancy Riyad Ahmed Hegazy, and Heba Salah Sayed Elbanna
While recognizing the etiology of community-acquired pneumonia is necessary for formulating local antimicrobial guidelines, limited data is published about this etiology in Egyptian pediatric patients.
To determine the frequency of bacterial and viral pathogens causing community-acquired pneumonia (CAP) among immunocompetent Egyptian infants and preschool children.
Ninety infants and preschool-age children admitted to our hospital with CAP were prospectively included in the study. Etiological agents were identified using conventional bacteriological identification methods and IgM antibodies detection against common atypical respiratory bacteria and viruses.
An etiology was identified in 59 patients (65.5%). Bacterial pathogens were detected in 43 (47.8%) of the cases while viral pathogens were detected in 23 (25.5%). Coinfection with more than one etiologic agent was evident in seven patients (7.8%). The most common typical bacterial cause of pneumonia was Staphylococcus aureus (n = 12, 13.3%), followed by Streptococcus pneumoniae and Klebsiella pneumoniae (n = 7, 7.8%, each). The commonest atypical bacterium was Mycoplasma pneumoniae (n = 10, 11.1%), whereas the commonest viral etiology was influenza viruses (n = 11, 12.2%).
Although we could not determine the causative agent in some studied cases, this study provides preliminary data regarding the spectrum and frequency of microorganisms causing CAP in Egyptian infants and preschool children.
Authors:I. Løbersli, A. L. Wester, Å. Kristiansen, and L. T. Brandal
A real-time polymerase chain reaction (PCR) assay, amplifying the genes encoding lactose permease (lacY) and invasion plasmid antigen H (ipaH), was run on 121 isolates phenotypically classified as Shigella spp., enteroinvasive Escherichia coli (EIEC), or EIEC O nontypable (ONT). The results were compared with data from a generic E. coli multiple-locus variable-number of tandem repeat analysis (MLVA) and a Shigella MLVA.
The real-time PCR verified all Shigella spp. (n = 53) as Shigella (lacY negative) and all EIEC O121 (n = 15) and EIEC O124 (n = 2) as EIEC (lacY positive). However, the real-time PCR typed EIEC O164 as either EIEC (n = 2) or Shigella (n = 2) and, thus, was not suited for classifying this group of isolates. Interestingly, the majority (42/47, 89.4%) of the EIEC ONT were classified as Shigella (lacY negative) by the real-time PCR, and in nearly all cases, (92.9%, 39/42) data from both MLVA assays supported these findings. Overall, in 94.7% (114/121) of the isolates, the results from the real-time PCR were substantiated by the results from the MLVA assays.
In conclusion, the real-time PCR assay was fast and accurate in differentiating Shigella spp. from EIEC, with the exception of the EIEC O164 group. This molecular assay was particularly pragmatic for the challenging EIEC ONT group.
Authors:G. Odewale, O. J. Adefioye, J. Ojo, F. A. Adewumi, and O. A. Olowe
Acinetobacter baumannii is a ubiquitous pathogen that has emerged as a major cause of healthcare-associated infections at Ladoke Akintola University Teaching Hospital. Isolates were assayed according to standard protocol. The isolates were subjected to molecular techniques to detect blaOXA, blaTEM, blaCTX-M, and blaSHV genes in strains of the A. baumannii isolates.
The prevalence of A. baumannii was 8.5% and was most prevalent among patients in the age group 51–60 (36%); the male patients (63.6%) were more infected than their female counterparts. Patients (72.7%) in the intensive care unit (ICU) were most infected with this organism. The isolates showed 100% resistance to both amikacin and ciprofloxacin and 90.9% to both ceftriaxone and ceftazidime, while resistance to the other antibiotics used in this study were: piperacillin (81.8%), imipenem (72.7%), gentamycin (72.2%), and meropenem (63.6%). None of the isolates was, however, resistant to colistin. PCR results showed that blaOXA, blaTEM, and blaCTX-M genes were positive in some isolates, while blaSHV was not detected in any of the isolates.
This study has revealed that the strains of A. baumannii isolated are multiple drug resistant. Regular monitoring, judicious prescription, and early detection of resistance to these antibiotics are, therefore, necessary to check further dissemination of the organism.
Authors:Hagen Frickmann, Wibke Schmeja, Emil Reisinger, Thomas Mittlmeier, Karen Mitzner, Norbert Georg Schwarz, Philipp Warnke, and Andreas Podbielski
This study assessed protective effects of a continuous introduction of safe instruments in terms of reduction of needle stick injuries. The retrospective study analyzed correlations between the increasing proportion of safe instruments and a reduction of the incidence of needle stick injuries linked to such instruments in a German university hospital over 5 years. Incidents declined about 17.6% from 80.3 incidents per 1000 employees to 66.2, associated with an increase in the proportions of injuries due to instruments without protective mechanisms such as scalpels or hypodermic needles by 12.2%. For injuries due to venipuncture cannulae in various surgical and internal medicine departments, there was a negative association between the proportion of safe instruments and the incidence of injuries. For injection needles, portacath needles, and lancets in selected internal medicine departments, the number of injuries also dropped during this study interval. However, there was no clear-cut association with the percentage of safe instruments. This observational study suggests a correlation between the implementation of use of safe instruments and the reduction of needle stick injuries in a case of a graduated implementation. However, the effects are much less pronounced than in previous interventional studies.