Andreas Erich Zautner

Capnocytophaga canimorsus is a fastidious Gram-negative rod transmitted from dog saliva and typically associated with immunocompromised hosts. We report meningitis in a 66-year-old immunocompetent dog owner with prior cerebral amyloid angiopathy who presented with acute global aphasia, fever and inflammatory cerebrospinal fluid (CSF) consistent with bacterial meningitis, but without meningism or history of any dog bite. Fusiform Gram-negative rods in CSF prompted extended culture in thioglycolate broth, enabling growth and subsequent species identification by MALDI-TOF MS as C. canimorsus within five days. Antimicrobial susceptibility testing was performed according to EUCAST guidance for situations without species-specific breakpoints and supported continuation of ceftriaxone-based therapy for a total of 15 days, resulting in complete clinical remission and normalization of CSF parameters. This case underlines that C. canimorsus meningitis can occur in apparently immunocompetent elderly patients, illustrates the diagnostic value of targeted culture strategies, and emphasizes the feasibility of EUCAST-guided susceptibility testing for this rare pathogen.

During a surveillance study conducted in Slovenia to investigate Campylobacter species from environmental waters, various Campylobacter coli isolates from clades 1 to 3 were isolated. Additionally, a Campylobacter isolate designated CCS1377, originating from the Classical Karst region near Illyrian Bistrica, was initially identified as a relative of C. coli through preliminary identification using multiplex PCR and MALDI-TOF MS. However, these methods did not allow a definite classification of the isolate. In-depth phenotypic analysis revealed characteristics of CCS1377 that were distinct from C. coli and Campylobacter jejuni type strains. This included a unique cell and colony morphology, non-motility, weak autoagglutination and an inability to assimilate succinate. MALDI-TOF MS analysis revealed distinct biomarker ions compared to C. coli RM2228, supporting the hypothesis that CCS1377 represents a novel species. Whole-genome sequencing and comparative genomics confirmed its distinct phylogenetic position. The chromosome of Campylobacter sp. CCS1377 was estimated to be 1,853,379 bp in size with a G+C content of 30.78 mol%, and the genome was predicted to contain 1,878 genes. Average nucleotide identity analysis against genomes available in the NCBI database yielded a maximum value of 81.2% when compared to C. coli type strain NCTC11366 ^T , significantly below the established species threshold of 94.2%. The digital DNA–DNA hybridization (dDDH) value was also below the species threshold of 70%, with dDDH d ₄ =22.0% [19.7–24.4%] in comparison to the C. coli type strain NCTC11366 ^T . Based on these phenotypic and genomic characteristics, we propose the name Campylobacter aecornae sp. nov. for the newly recognized Campylobacter species. The proposed type strain is CCS1377 ^T (=DSM 102056 ^T =LMG 33651 ^T ).

Objectives: This observational and cross-sectional study investigated differential associations between entero-invasive and non-entero-invasive enteric pathogens and HIV infection, considering socioeconomic, clinical and immunological aspects. In a Ghanaian population with a high prevalence of enteric pathogens, stool samples from people living with HIV (PLWH) were screened for Salmonella spp., Shigella spp./EIEC (enteroinvasive Escherichia coli), and Campylobacter jejuni as entero-invasive bacteria, for enteropathogenic E. coli (EPEC), enterotoxigenic E. coli (ETEC), and enteroaggregative E. coli (EAEC) as non-entero-invasive bacteria. Arcobacter butzleri, with uncertain enteropathogenicity, was also included. Methods: Stool samples from PLWH (with and without antiretroviral therapy) and HIV-negative controls were analyzed by real-time PCR for the presence and quantity of the selected enteropathogens. Results were correlated with socioeconomic, clinical, and immunological parameters. Results: The presence of Shigella spp. /EIEC in stool was both qualitatively and quantitatively associated with reduced CD4+ T lymphocyte counts and was qualitatively associated with clinically apparent diarrhea. EAEC showed a weak positive association with HIV infection, supported by a negative correlation between EAEC DNA quantity and CD4+ T lymphocyte counts. EPEC colonization was associated with HIV negativity, higher CD4+ T lymphocyte counts, and lower socioeconomic status. Abundance of Salmonella enterica was associated with clinically apparent diarrhea. Conclusions: This explorative, hypothesis-forming study suggests species- or pathovar-specific associations between enteric bacterial pathogens and HIV-related immunosuppression. Observed relationships with clinically apparent diarrhea largely align with findings from sub-Saharan African children, except for a more pronounced association between diarrhea and Salmonella in this cohort.

Molecular diagnoses of Entamoeba histolytica and Strongyloides stercoralis in human samples are becoming increasingly common. To contribute to the ongoing standardization of molecular diagnostic approaches targeting these parasites, we compared three published E. histolytica- and S. stercoralis-specific real-time PCR assays in test comparisons without a reference standard. Latent class analysis (LCA) was used to calculate diagnostic accuracy estimations for the three compared assays per parameter. The comparison was conducted using stool samples from Ghanaian individuals. In the course of the assessment of 873 stool samples, the number of detected positive PCR results ranged from 10 to 15 for S. stercoralis and from 4 to 54 for E. histolytica depending on the applied assay. Diagnostic accuracy estimates of real-time PCR sensitivity for S. stercoralis and E. histolytica ranged from 89% to 100% and from 75% to 100%, respectively; diagnostic estimates of specificity ranged from 99% to 100% and from 94% to 100%, respectively. Diagnostic accuracy-adjusted prevalence estimates were 1.2% for S. stercoralis and 0.5% for E. histolytica. High cycle threshold values of real-time PCR > 35 showed a particularly reduced likeliness of reproducibility when applying competitor real-time PCR assays. There were no clear-cut differences in terms of diagnostic accuracy favoring either small-subunit ribosomal ribonucleic acid (SSU rRNA) gene sequences or the S. stercoralis dispersed repetitive sequence for S. stercoralis PCR. The same applied to the comparison of real-time PCRs targeting SSU rRNA gene sequences and the SSU rRNA episomal repeat sequence (SREPH) of E. histolytica. In conclusion, interchangeability of the compared real-time PCR assays was higher for the assessed S. stercoralis assays compared with the assessed E. histolytica assays. Regional diagnostic accuracy testing seems advisable before literature-adapted assays for rare tropical pathogens like S. stercoralis and E. histolytica are applied in different study regions.

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.

Introduction: Entamoeba histolytica is the causative agent of enteric amebiasis in human patients. Partly controversial hypotheses have been proposed regarding the potential impact of the immunological status of patients as well as HIV (human immunodeficiency virus) positivity on the prevalence and clinical course of amebiasis.Methods: To investigate a potential interplay between the epidemiology of E. histolytica and immunological markers of Ghanaian HIV patients, real-time PCR targeting E. histolytica DNA in stool samples was conducted on a cohort of 595 clinically and immunologically well-characterized adult Ghanaian HIV patients, along with 82 HIV negative control-individuals.Results: E. histolytica DNA was more prevalent in the HIV-negative control group (12.2%, n = 10/82) compared to the HIV-positive subpopulation (3.5%, n = 21/595, P = 0.001). Among HIV-positive individuals, the prevalence of E. histolytica DNA was 4.2% in subjects with CD4+ T cell counts above 200 cells/µL, 3.3% in case of 50 and 200 cells/µL, and 0% in case of less than 50 cells/µL. In the group of ART-exposed HIV-positive individuals, E. histolytica positivity was associated to lower CD4+/CD8+ cell ratios.Conclusions: The study suggested a negative association of E. histolytica DNA detections with HIV-positivity and with the degree of HIV infection-associated immunosuppression.

Campylobacter coli, a significant foodborne pathogen, has undergone extensive genetic exchange with its close relative, Campylobacter jejuni, leading to the emergence of three distinct clades. While clade 1 strains are commonly isolated from clinical and agricultural sources, clades 2 and 3 are primarily found in aquatic environments. This study aimed to enhance our understanding of C. coli clade 2 and 3 isolates through genomic and phenotypic characterization. A total of 48 surface water samples were collected from 19 different water bodies throughout Slovenia, and eleven Campylobacter isolates initially identified as C. coli from clades 2 and 3 were cultured. Whole genome sequencing was then performed on these isolates. Phylogenetic analysis was conducted using core genome multilocus sequence typing (cgMLST) and k-mer analysis. Phenotypic characterization included growth analysis, autoagglutination, biofilm formation, motility, antimicrobial susceptibility, water survival, and metabolic profiling. Genomic analysis revealed significant admixture with other Campylobacter species in the clade 2 and 3 isolates. One isolate was found to represent a new species related to C. coli. Besides C. jejuni and C. lari, this novel species appears to have contributed to introgression in the C. coli clades 2 and 3 isolates. Phenotypic characterization demonstrated diverse growth patterns, motility, autoagglutination abilities, and biofilm formation among the isolates. This study provides new insights into the genetic diversity and phenotypic characteristics of aquatic C. coli clade 2 and 3 isolates from Slovenia. The observed admixture with other Campylobacter species highlights the complex evolutionary history of these environmental strains and underscores the importance of continued surveillance and characterization of Campylobacter isolates from diverse ecological niches.

This work aimed to investigate interactions between antibody-opsonized SARS-CoV-2 and monocytes enriched from human peripheral blood mononuclear cells (PBMC) to determine whether antibody dependent enhancement might contribute to the pathophysiology of COVID-19. Pre-incubation of SARS-CoV-2 with sera from hospitalized COVID-19 patients led to significantly increased virus uptake and viral replication in monocytes. Remarkably, SARS-CoV-2 pre-incubated with sera from patients with severe COVID-19 but not those with mild disease or post vaccination strongly increased IL-6 secretion by monocytes. Antibody dependent viral uptake was partially inhibited by monoclonal anti-FcγRIIa antibody whereas IL-6 secretion was completely abolished. FcγRIIa preferentially binds IgG2, and sera from patients with severe COVID-19 contained lower IgG2 levels as compared to mild COVID-19 cases whereas IgG1 levels were increased. These data suggests that FcγRIIa-mediated binding of antibody-opsonized SARS-CoV-2 critically impacts monocytic inflammatory cytokine release and COVID-19 pathophysiology.

Purpose Lautropia mirabilis is a Gram-negative, facultative anaerobic coccus, which has been detected mainly in respiratory sites of immunodeficient patients suffering from HIV or cystic fibrosis. To date, knowledge about the pathogenicity of L. mirabilis is spare due to the small numbers of documented cases. Methods We present a literature review and report the case of a 39-year-old female diagnosed with common variable immunodeficiency (CVID) with IgG and IgA deficiency suffering from a sepsis with L. mirabilis. As no fully closed L. mirabilis genome besides the type strain was available to date, we additionally performed complete genome sequencing of L. mirabilis. Results The patient was admitted to our hospital with recurrent episodes of fever. Here, we detected L. mirabilis in two different blood cultures. The bacterium was tested susceptible to and treated with meropenem. As the origin of L. mirabilis sepsis, we observed an active periodontitis likely due to impaired IgA levels and mucosal insufficiency as a consequence of CVID. Whole genome sequencing of L. mirabilis revealed several genes important for host cell invasion and intracellular survival of the pathogen. Conclusions Our case highlights the importance of L. mirabilis in immunocompromised patients also in other compartments than the respiratory tract.