Rapid Bacteria Detection from Patients' Blood Bypassing Classical Bacterial Culturing.

Sepsis is a life-threatening condition mostly caused by a bacterial infection resulting in inflammatory reaction and organ dysfunction if not treated effectively. Rapid identification of the causing bacterial pathogen already in the early stage of bacteremia is therefore vital. Current technologies still rely on time-consuming procedures including bacterial culturing up to 72 h. Our approach is based on ultra-rapid and highly sensitive nanomechanical sensor arrays. In measurements we observe two clearly distinguishable distributions consisting of samples with bacteria and without bacteria respectively. Compressive surface stress indicates the presence of bacteria. For this proof-of-concept, we extracted total RNA from EDTA whole blood samples from patients with blood-culture-confirmed bacteremia, which is the reference standard in diagnostics. We determined the presence or absence of bacterial RNA in the sample through 16S-rRNA hybridization and species-specific probes using nanomechanical sensor arrays. Via both probes, we identified two clinically highly-relevant bacterial species i.e., Escherichia coli and Staphylococcus aureus down to an equivalent of 20 CFU per milliliter EDTA whole blood. The dynamic range of three orders of magnitude covers most clinical cases. We correctly identified all patient samples regarding the presence or absence of bacteria. We envision our technology as an important contribution to early and sensitive sepsis diagnosis directly from blood without requirement for cultivation. This would be a game changer in diagnostics, as no commercial PCR or POCT device currently exists who can do this.

Performance of four bacterial cell counting apps for smartphones.

Quantifying bacterial colony forming units is important in microbiological diagnostics. Recent progress in imaging technology allows automation of this tedious and error-prone task. We compared the accuracy of four smartphone colony counter applications conducting standardized measurements, using a self-built apparatus. One app showed high accuracy at lower colony counts.

Multicenter Technical Validation of 30 Rapid Antigen Tests for the Detection of SARS-CoV-2 (VALIDATE).

During COVID19 pandemic, SARS-CoV-2 rapid antigen tests (RATs) were marketed with minimal or no performance data. We aimed at closing this gap by determining technical sensitivities and specificities of 30 RATs prior to market release. We developed a standardized technical validation protocol and assessed 30 RATs across four diagnostic laboratories. RATs were tested in parallel using the Standard Q® (SD Biosensor/Roche) assay as internal reference. We used left-over universal transport/optimum media from nasopharyngeal swabs of 200 SARS-CoV-2 PCR-negative and 100 PCR-positive tested patients. Transport media was mixed with assay buffer and applied to RATs according to manufacturer instructions. Sensitivities were determined according to viral loads. Specificity of at least 99% and sensitivity of 95%, 90%, and 80% had to be reached for 107, 106, 105 virus copies/mL, respectively. Sensitivities ranged from 43.5% to 98.6%, 62.3% to 100%, and 66.7% to 100% at 105, 106, 107 copies/mL, respectively. Automated assay readers such as ExDia or LumiraDx showed higher performances. Specificities ranged from 88.8% to 100%. Only 15 of 30 (50%) RATs passed our technical validation. Due to the high failure rate of 50%, mainly caused by lack of sensitivity, we recommend a thorough validation of RATs prior to market release.

B1 cells are unaffected by immune modulatory treatment in remitting-relapsing multiple sclerosis patients.

In this study we aimed to investigate whether treatment with an immune modulatory drug had an effect on the distribution of B cell subpopulations in patients with remitting-relapsing multiple sclerosis (RRMS). We investigated the first-line drugs glatiramer acetate, interferon-ß and natalizumab. Our data show that the frequency of the CD27(+)CD43(+) B1 cell subset was significantly diminished in RRMS patients compared to healthy subjects and that this subset was unaffected by treatment. Regardless of their true nature, we believe that these cells are part of the autoimmune disease pattern.

Burkholderia species are major inhabitants of white lupin cluster roots.

The formation of cluster roots by plants represents a highly efficient strategy for acquisition of sparingly available phosphate. This particular root type is characterized by a densely branched structure and high exudation of organic acids and protons, which are likely to influence the resident bacterial community. Until now, the identity of the bacterial populations living in cluster roots has not been investigated. We applied cultivation-dependent and cultivation-independent methods to characterize the dominant bacterial genera inhabiting the growing cluster roots of white lupin. We observed a high relative abundance of Burkholderia species (up to 58% of all isolated strains and 44% of all retrieved 16S rRNA sequences) and a significant enrichment with increasing cluster root age. Most of the sequences retrieved clustered together with known plant- or fungus-associated Burkholderia species, while only one of 98 sequences was affiliated with the Burkholderia cepacia complex. In vitro assays revealed that Burkholderia strains were much more tolerant to low pH than non-Burkholderia strains. Moreover, many strains produced large amounts of siderophores and were able to utilize citrate and oxalate as carbon sources. These features seem to represent important traits for the successful colonization and maintenance of Burkholderia species in white lupin cluster roots.

Antipropionibacterial activity of BAL19403, a novel macrolide antibiotic.

BAL19403 exemplifies a new family of macrolide antibiotics with excellent in vitro activity against propionibacteria. MICs indicated that BAL19403 was very active against erythromycin-resistant and clindamycin-resistant propionibacteria with mutations in the region from positions 2057 to 2059 (Escherichia coli numbering) of the 23S rRNA, although it is less active against those rare clinical isolates in which a methyltransferase, ErmX, confers macrolide and lincosamide resistance by dimethylation of the adenine moiety at position 2058. BAL19403 was predominantly bacteriostatic toward the propionibacteria, and population analyses indicated resistance selection frequencies for BAL19403 and the comparator drugs (erythromycin, clindamycin) in the range 10(-8) to 10(-9) for cutaneous propionibacteria with diverse antibiotic resistance profiles. On the basis of its antipropionibacterial activity and its high anti-inflammatory activity, BAL19403 represents a promising topical treatment for mild to moderate inflammatory acne vulgaris.

Antimicrobial and DNA gyrase-inhibitory activities of novel clorobiocin derivatives produced by mutasynthesis.

Twenty-eight novel clorobiocin derivatives obtained from mutasynthesis experiments were investigated for their inhibitory activity towards Escherichia coli DNA gyrase and for their antibacterial activities towards clinically relevant gram-positive and gram-negative bacteria in comparison to novobiocin and clorobiocin. Clorobiocin was the most active compound both against E. coli DNA gyrase in vitro and against bacterial growth. All tested modifications of the 3-dimethylallyl-4-hydroxybenzoyl moiety reduced biological activity. The highest activities were shown by compounds containing a hydrophobic alkyl substituent at position 3 of the 4-hydroxybenzoyl moiety. Polar groups in this side chain, especially amide functions, strongly reduced antibacterial activity. Replacement of the alkyl side chain with a halogen atom or a methoxy group at the same position markedly reduced activity. Transfer of the pyrrole carboxylic acid moiety from O-3" to O-2" of L-noviose moderately reduced activity, whereas the complete absence of the pyrrole carboxylic acid moiety led to a loss of activity. Desclorobiocin derivatives lacking the chlorine atom at C-8 of the 3-amino-4,7-dihydroxycoumarin moiety also showed low activity. Lack of a methyl group at O-4" of L-noviose resulted in an inactive compound. From these findings it appears that clorobiocin represents a "highly evolved" structure optimized for bacterial transport and DNA gyrase inhibition.