Explore the vast range of titles available.

Infectious diseases are worldwide a major cause of morbidity and mortality. Fast and specific detection of pathogens such as bacteria is needed to combat these diseases. Optimal methods would be non-invasive and without extensive sample-taking/processing. Here, we developed a set of near infrared (NIR) fluorescent nanosensors and used them for remote fingerprinting of clinically important bacteria. The nanosensors are based on single-walled carbon nanotubes (SWCNTs) that fluoresce in the NIR optical tissue transparency window, which offers ultra-low background and high tissue penetration. They are chemically tailored to detect released metabolites as well as specific virulence factors (lipopolysaccharides, siderophores, DNases, proteases) and integrated into functional hydrogel arrays with 9 different sensors. These hydrogels are exposed to clinical isolates of 6 important bacteria ( Staphylococcus aureus , Escherichia coli,…) and remote (≥25 cm) NIR imaging allows to identify and distinguish bacteria. Sensors are also spectrally encoded (900 nm, 1000 nm, 1250 nm) to differentiate the two major pathogens P. aeruginosa as well as S. aureus and penetrate tissue (>5 mm). This type of multiplexing with NIR fluorescent nanosensors enables remote detection and differentiation of important pathogens and the potential for smart surfaces. Fast and specific detection of pathogenic bacteria is needed to combat infections. Here the authors generate an array of near-infrared biosensors based on carbon nanotubes to detect released metabolites and virulence factors and use them to distinguish pathogens such as S. aureus and P. aeruginosa.

Background All gastrointestinal pathogens, including Enterococcus faecalis and Enterococcus faecium , undergo adaptation processes during colonization and infection. In this study, we investigated by data-independent acquisition mass spectrometry (DIA-MS) two crucial adaptations of these two Enterococcus species at the proteome level. Firstly, we examined the adjustments to cope with bile acid concentrations at 0.05% that the pathogens encounter during a potential gallbladder infection. Therefore, we chose the primary bile acids cholic acid (CA) and chenodeoxycholic acid (CDCA) as well as the secondary bile acid deoxycholic acid (DCA), as these are the most prominent bile acids. Secondly, we investigated the adaptations from an aerobic to a microaerophilic environment, as encountered after oral-fecal infection, in the absence and presence of deoxycholic acid (DCA). Results Our findings showed similarities, but also species-specific variations in the response to the different bile acids. Both Enterococcus species showed an IC 50 in the range of 0.01- 0.023% for DCA and CDCA in growth experiments and both species were resistant towards 0.05% CA. DCA and CDCA had a strong effect on down-expression of proteins involved in translation, transcription and replication in E. faecalis (424 down-expressed proteins with DCA, 376 down-expressed proteins with CDCA) and in E. faecium (362 down-expressed proteins with DCA, 391 down-expressed proteins with CDCA). Proteins commonly significantly altered in their expression in all bile acid treated samples were identified for both species and represent a “general bile acid response”. Among these, various subunits of a V-type ATPase, different ABC-transporters, multi-drug transporters and proteins related to cell wall biogenesis were up-expressed in both species and thus seem to play an essential role in bile acid resistance. Most of the differentially expressed proteins were also identified when E. faecalis was incubated with low levels of DCA at microaerophilic conditions instead of aerobic conditions, indicating that adaptations to bile acids and to a microaerophilic atmosphere can occur simultaneously. Conclusions Overall, these findings provide a detailed insight into the proteomic stress response of two Enterococcus species and help to understand the resistance potential and the stress-coping mechanisms of these important gastrointestinal bacteria.

Background and Objectives Rifaximin (RFX) has recently been suggested as an alternative treatment option for Clostridioides difficile infection. This study reports the survey on RFX susceptibility within a C. difficile test cohort that represents the five clinically relevant phylogenetic clades. Methods Agar dilution assays were conducted to determine the minimum inhibitory concentrations (MICs) of RFX for 129 clinical C. difficile isolates from Germany (86), Indonesia (29), and Ghana (14). Genome sequence data were obtained for 50 representative isolates, including all those with a minimum inhibitory concentration MIC[RFX] of ≥ 32.0 µg/mL, to identify the underlying rpoB gene resistance alleles, determine the multilocus sequence typing (MLST) sequence types (STs), and infer phylogenetic relatedness. Results 10.1% of the isolates were found to be resistant to RFX. The resistance rate varies by region, with 4.7% in Germany, 27.6% in Indonesia, and 7.1% in Ghana. Three distinct rpoB alleles were associated with RFX resistance. The presence of a specific rpoB allele correlates with the MLST-based ST of the isolate, indicating that the rifaximin-resistant isolates belong to phylogenetic clades 1, 2, and 4. These isolates are represented by six different ribotypes: 010, 017, 027, 046, 084, and 131. Furthermore, we identified seven amino acid substitutions resulting from SNPs in the rpoB gene through alignment analysis. These substitutions are found in both RFX-resistant and susceptible isolates, suggesting that they are neutral mutations in relation to RFX susceptibility. These observations also indicate that RFX resistance arose independently in different clades. Conclusions A substantial rate of RFX resistance, particularly among Indonesian isolates, was observed. This may be attributed to the prolonged use of rifampicin, especially in the treatment of tuberculosis. RFX resistance has been linked to specific amino acid substitutions in the β-subunit of RNA polymerase encoded by the rpoB gene. To the best of our knowledge, one of the identified RFX resistance-associated rpoB alleles (H502N, R505K, I750M) has not been previously described, whereupon, the amino acid substitutions I750M as well as I750V, E1037Q, A1205V, N1207A, A1208T, and D1232E were identified as neutral mutations that do not confer resistance to RFX.

Although Campylobacter jejuni-infections have a high prevalence worldwide and represent a significant socioeconomic burden, it is still not well understood how C. jejuni causes intestinal inflammation. Detailed investigation of C. jejuni-mediated intestinal immunopathology is hampered by the lack of appropriate vertebrate models. In particular, mice display colonization resistance against this pathogen. To overcome these limitations we developed a novel C. jejuni-infection model using gnotobiotic mice in which the intestinal flora was eradicated by antibiotic treatment. These animals could then be permanently associated with a complete human (hfa) or murine (mfa) microbiota. After peroral infection C. jejuni colonized the gastrointestinal tract of gnotobiotic and hfa mice for six weeks, whereas mfa mice cleared the pathogen within two days. Strikingly, stable C. jejuni colonization was accompanied by a pro-inflammatory immune response indicated by increased numbers of T- and B-lymphocytes, regulatory T-cells, neutrophils and apoptotic cells, as well as increased concentrations of TNF-α, IL-6, and MCP-1 in the colon mucosa of hfa mice. Analysis of MyD88(-/-), TRIF(-/-), TLR4(-/-), and TLR9(-/-) mice revealed that TLR4- and TLR9-signaling was essential for immunopathology following C. jejuni-infection. Interestingly, C. jejuni-mutant strains deficient in formic acid metabolism and perception induced less intestinal immunopathology compared to the parental strain infection. In summary, the murine gut flora is essential for colonization resistance against C. jejuni and can be overcome by reconstitution of gnotobiotic mice with human flora. Detection of C. jejuni-LPS and -CpG-DNA by host TLR4 and TLR9, respectively, plays a key role in immunopathology. Finally, the host immune response is tightly coupled to bacterial formic acid metabolism and invasion fitness. We conclude that gnotobiotic and \"humanized\" mice represent excellent novel C. jejuni-infection and -inflammation models and provide deep insights into the immunological and molecular interplays between C. jejuni, microbiota and innate immunity in human campylobacteriosis.

Systemic infections caused by Salmonella enterica are an ongoing public health problem especially in Sub-Saharan Africa. Essentially typhoid fever is associated with high mortality particularly because of the increasing prevalence of multidrug-resistant strains. Thus, a rapid blood-culture based bacterial species diagnosis including an immediate sub-differentiation of the various serovars is mandatory. At present, MALDI-TOF based intact cell mass spectrometry (ICMS) advances to a widely used routine identification tool for bacteria and fungi. In this study, we investigated the appropriateness of ICMS to identify pathogenic bacteria derived from Sub-Saharan Africa and tested the potential of this technology to discriminate S. enterica subsp. enterica serovar Typhi (S. Typhi) from other serovars. Among blood culture isolates obtained from a study population suffering from febrile illness in Ghana, no major misidentifications were observed for the species identification process, but serovars of Salmonella enterica could not be distinguished using the commercially available Biotyper database. However, a detailed analysis of the mass spectra revealed several serovar-specific biomarker ions, allowing the discrimination of S. Typhi from others. In conclusion, ICMS is able to identify isolates from a sub-Saharan context and may facilitate the rapid discrimination of the clinically and epidemiologically important serovar S. Typhi and other non-S. Typhi serovars in future implementations.

Background Motility in bacteria forms the basis for taxis and is in some pathogenic bacteria important for virulence. Video tracking of motile bacteria allows the monitoring of bacterial swimming behaviour and taxis on the level of individual cells, which is a prerequisite to study the underlying molecular mechanisms. Results The open-source python program YSMR (Your Software for Motility Recognition) was designed to simultaneously track a large number of bacterial cells on standard computers from video files in various formats. In order to cope with the high number of tracked objects, we use a simple detection and tracking approach based on grey-value and position, followed by stringent selection against suspicious data points. The generated data can be used for statistical analyses either directly with YSMR or with external programs. Conclusion In contrast to existing video tracking software, which either requires expensive computer hardware or only tracks a limited number of bacteria for a few seconds, YSMR is an open-source program which allows the 2-D tracking of several hundred objects over at least 5 minutes on standard computer hardware. The code is freely available at https://github.com/schwanbeck/YSMR

Background. Treatment of Toxoplasma gondii infection acquired during pregnancy differs in many countries. In Germany, spiramycin is given until the 16th week of pregnancy, followed by at least 4 weeks of combination therapy with pyrimethamine, sulfadiazine, and folinic acid independent of the infection stage of the fetus. If infection of the fetus is confirmed by polymerase chain reaction or if fetal ultrasound indicates severe symptoms (hydrocephalus, ventricular dilation), treatment is continued until delivery with regular monitoring of pyrimethamine and sulfadiazine concentration in maternal blood and observation of possible adverse effects. In other European countries, such as France, only spiramycin is given unless infection of the fetus is proven. Methods. To evaluate the effectiveness of the German treatment scheme, a retrospective analysis of 685 women who showed a serological constellation consistent with primary infection in pregnancy and their children was performed. Results. We found an increased transmission rate to the fetus with increased time in gestation and a decreased risk of clinical manifestations. In comparison with studies performed in other countries, the overall transmission rate (4.8%) and the rate of clinical manifestations in newborns (1.6%) were lower. Conclusions. Use of spiramycin from time of diagnosis of acute acquisition of infection by the pregnant woman until week 16, followed by pyrimethamine, sulfadiazine, and folinic acid for at least 4 weeks in combination with a standardized follow-up program is efficient in reducing transplacental transmission of the parasite and the burden of disease in the newborn.

Background The main natural reservoir for Campylobacter jejuni is the avian intestinal tract. There, C. jejuni multiplies optimally at 42 °C – the avian body temperature. After infecting humans through oral intake, the bacterium encounters the lower temperature of 37 °C in the human intestinal tract. Proteome profiling by label-free mass spectrometry (DIA-MS) was performed to examine the processes which enable C. jejuni 81–176 to thrive at 37 °C in comparison to 42 °C. In total, four states were compared with each other: incubation for 12 h at 37 °C, for 24 h at 37 °C, for 12 h at 42 °C and 24 h at 42 °C. Results It was shown that the proteomic changes not only according to the different incubation temperature but also to the length of the incubation period were evident when comparing 37 °C and 42 °C as well as 12 h and 24 h of incubation. Altogether, the expression of 957 proteins was quantifiable. 37.1 − 47.3% of the proteins analyzed showed significant differential regulation, with at least a 1.5-fold change in either direction (i.e. log 2 FC ≥ 0.585 or log 2 FC ≤ -0.585) and an FDR-adjusted p -value of less than 0.05. The significantly differentially expressed proteins could be arranged in 4 different clusters and 16 functional categories. Conclusions The C. jejuni proteome at 42 °C is better adapted to high replication rates than that at 37 °C, which was in particular indicated by the up-regulation of proteins belonging to the functional categories “replication” (e.g. Obg, ParABS, and NapL), “DNA synthesis and repair factors” (e.g. DNA-polymerase III, DnaB, and DnaE), “lipid and carbohydrate biosynthesis” (e.g. capsular biosynthesis sugar kinase, PrsA, AccA, and AccP) and “vitamin synthesis, metabolism, cofactor biosynthesis” (e.g. MobB, BioA, and ThiE). The relative up-regulation of proteins with chaperone function (GroL, DnaK, ClpB, HslU, GroS, DnaJ, DnaJ-1, and NapD) at 37 °C in comparison to 42 °C after 12 h incubation indicates a temporary lower-temperature proteomic response. Additionally the up-regulation of factors for DNA uptake (ComEA and RecA) at 37 °C compared to 42 °C indicate a higher competence for the acquisition of extraneous DNA at human body temperature.

Chronic infected wounds are generally difficult to manage and treatment can be particularly challenging in resource-limited settings where diagnostic testing is not readily available. In this study, the epidemiology of microbial pathogens in chronically infected wounds in rural Ghana was assessed to support therapeutic choices for physicians. Culture-based bacterial diagnostics including antimicrobial resistance testing were performed on samples collected from patients with chronic wounds at a hospital in Asante Akim North Municipality, Ghana. Fungal detection was performed by broad-range fungal PCR and sequencing of amplicons. In total, 105 patients were enrolled in the study, from which 207 potential bacterial pathogens were isolated. Enterobacteriaceae (n = 84, 41%) constituted the most frequently isolated group of pathogens. On species level, Pseudomonas aeruginosa (n = 50, 24%) and Staphylococcus aureus (n = 28, 14%) were predominant. High resistance rates were documented, comprising 29% methicillin resistance in S. aureus as well as resistance to 3.sup.rd generation cephalosporins and fluoroquinolones in 33% and 58% of Enterobacteriaceae, respectively. One P. aeruginosa strain with carbapenem resistance was identified. The most frequently detected fungi were Candida tropicalis. The pathogen distribution in chronic wounds in rural Ghana matched the internationally observed patterns with a predominance of P. aeruginosa and S. aureus. Very high resistance rates discourage antibiotic therapy but suggest an urgent need for microbiological diagnostic approaches, including antimicrobial resistance testing to guide the management of patients with chronic wounds in Ghana.

Background Although infectious diseases still account for a high burden of morbidity and mortality in sub-Saharan Africa, simultaneous investigations on multiple infections affecting maternal and child health are missing. Methods We conducted a cross-sectional, single-centre pilot study in a rural area of Ghana to assess the infectiological profile during pregnancy. Screening of 180 expectant mothers was done by vaginal swabs and serology to detect the most common pregnancy-relevant infections. They were also interviewed for potential risk factors, outcome of previous pregnancies, and socio-economic aspects. Results We found a high prevalence of infections caused by hepatitis B virus (16.7% HBs antigen positive). In contrast, infections caused by hepatitis C virus (1.1% anti-HCV) and HIV (0.6%) were rare. Maternal malaria was frequent (10.6%), despite increasing acceptance of intermittent preventive treatment during pregnancy (IPTp). Group B streptococci were present in 10.6% of all pregnant women. Absence of antibodies against varicella zoster virus in 43.2%, Toxoplasma gondii in 26.8%, parvovirus B19 in 20.0%, and rubella virus in 15.7% makes a significant proportion of pregnant women susceptible for acquiring primary infections. Whereas all study participants had specific IgG antibodies against human cytomegalovirus, infections with Listeria , Brucella , or Neisseria gonorrhoeae as well as active syphilis were absent. Conclusions Our pilot study in a rural community in Ghana indicates an urgent need for action in dealing at least with high-prevalent pregnancy-relevant infections, such as hepatitis B, malaria and those caused by group B streptococci. In addition, the resulting prevalence rates of various other infections may offer guidance for health officials to prioritize possible future intervention schemes.