Hendrik Koliwer-Brandl

Gonococcal and chlamydial conjunctivitis and keratoconjunctivitis are potentially sight-threatening ocular manifestations of sexually transmitted infections. Recent epidemiological data indicate rising rates of gonorrhoea and chlamydia infections worldwide, raising concerns about a possible increase in associated ocular infections. This retrospective single-center study analyzed the frequency and temporal trends of laboratory-confirmed gonococcal and chlamydial ocular infections in adults treated at the University Hospital Zurich between January 2005 and July 2025. Clinical characteristics, treatment, complications, and outcomes were additionally assessed for gonococcal cases. We identified 17 gonococcal and 121 chlamydial conjunctivitis or keratoconjunctivitis cases over the past approximately 20.5 years. A marked increase in gonococcal cases was observed between 2021 and 2025 (p < 0.0001), during which 70.6% of all cases were diagnosed. Complications occurred in 41.1% of gonococcal infections, including one corneal perforation requiring keratoplasty. Although gonococcal conjunctivitis and keratoconjunctivitis remain rare, their recent increase and risk of severe ocular complications highlight the importance of early recognition and prompt treatment. In contrast, chlamydial conjunctivitis was more common, affected a younger population, and showed a significant declining trend, with an average annual decrease of 5% (p = 0.0015).

Recurrent urinary tract infections are recalcitrant and difficult-to-treat bacterial infections that primarily affect women. Here we combine phage therapy with faecal microbiota transplantation to decolonize the urinary and intestinal reservoirs of patients with recurrent urinary tract infections. Three women received oral and intravesical phage therapy for 8 days, and two underwent subsequent faecal microbiota transplantation. Treatments were well tolerated, and although Escherichia coli was detected in follow-up samples, patients experienced none or fewer and less severe episodes of urinary tract infection 24 months post-treatment.

During infection, pathogenic mycobacteria damage the membrane of the Mycobacterium -containing vacuole (MCV), triggering host repair responses that preserve an intracellular permissive niche before bacteria escape to the cytosol at later stages. How the MCV transitions from repairable injury to catastrophic rupture remains poorly understood. Here, we dissected the respective contributions of the ESX-1 effectors EsxA/EsxB and the cell-envelope lipid phthiocerol dimycocerosate (PDIM) during Mycobacterium marinum infection of the amoeba Dictyostelium discoideum . Combining host reporters for membrane damage and repair with single and double bacterial mutants, we show that EsxA/EsxB and PDIM are both required for full intracellular virulence but act at distinct stages of MCV damage progression. Loss of EsxA/EsxB strongly reduced recruitment of ESCRT and autophagy reporters to the MCV, demonstrating that EsxA initiates repairable membrane lesions. In contrast, PDIM-deficient bacteria retained the ability to recruit early damage reporters and ESCRT machinery but showed reduced autophagy-associated repair, failed to efficiently acquire cytosolic perilipin coating, and remained largely confined within the MCV. Genetic disruption of host autophagy restored cytosolic access and intracellular growth of PDIM-deficient bacteria, indicating that PDIM is specifically required to overcome host repair capacity rather than to initiate damage. Importantly, the sequential requirement for EsxA and PDIM was conserved during infection of murine microglial BV-2 cells. Remarkably, PDIM-defective mutants induced lysenin recruitment, a reporter of sphingomyelin exposure, but progression to autophagy engagement was strongly decreased. Together, our results support a two-step model in which EsxA initiates MCV membrane damage, while PDIM amplifies these lesions towards catastrophic rupture, enabling escape to the cytosol and dissemination.

Antimicrobial susceptibility testing (AST) is being reshaped by increasingly complex resistance mechanisms, revised interpretive frameworks, and rapid phenotypic and genomic technologies. The first Swiss-EUCAST AST Meeting, held in Zurich on 4 May 2026, brought together more than 100 clinical microbiologists, researchers, and infectious diseases specialists to discuss how these developments should be translated into routine diagnostics. The meeting focused on three topics: the limitations of genotype-phenotype prediction, the ongoing need for standardized interpretation within the European Committee on Antimicrobial Susceptibility Testing (EUCAST), and the potential of new technologies to reduce turnaround times. Discussions specifically on Pseudomonas aeruginosa, as well as on pathogens without clinical breakpoints, carbapenemase-producing Enterobacterales, expected phenotypes, epidemiological cutoff values, rapid phenotypic susceptibility tests, and whole-genome sequencing, showed that no single method can eliminate all diagnostic uncertainties. In summary, it was concluded that standardized phenotypic ASTs will continue to serve as a clinical reference in the future, but molecular and genomic methods offer additional advantages in terms of speed, as well as insights into mechanisms of action and epidemiological relations.

Recurrent urinary tract infections (rUTIs) are a chronic, debilitating condition characterized by repeated infections and treatment failure with antibiotics. We present an attempt to decolonize the urinary and intestinal reservoirs between acute UTI episodes in three female patients suffering from rUTI caused by Escherichia coli using a combined approach of semi-personalized phage therapy followed by fecal microbiota transplantation (FMT). Patients with long-term urinary detection of phage-susceptible E. coli received eight days of oral and intravesical phage application followed by antibiotics prior to FMT. Pathogen titers decreased significantly after local administration, and phage concentrations were maintained in the urine between doses after several days. While E. coliwas detected in follow-up samples, patients experienced less frequent and less severe episodes of acute UTI 24 months post-treatment. Genetic analysis of pre- and post-treatment strains revealed a strain replacement for one patient. Metagenomic shotgun sequencing of stool samples confirmed engraftment in FMT recipients.

Purpose: To investigate the light transmission (LT) of UV-A and green light through infected corneas saturated with riboflavin or rose bengal in an ex vivo porcine model for infectious keratitis. Setting: University of Zurich, Zurich, Switzerland, and Empa, St. Gallen, Switzerland. Design: Laboratory study. Methods: Ex vivo porcine eyes (n = 162) were divided into 3 groups: control eyes, eyes infected with Staphylococcus aureus, and eyes infected with Pseudomonas aeruginosa. Corneas remained either uninfected or were infected with S. aureus and P. aeruginosa and were either left untreated or were instilled with 0.1% riboflavin or 0.1% rose bengal. Corneal buttons were prepared, and corneal LT was measured at 365 nm and 522 nm using a spectrophotometer. LT values were calculated and compared. Transmission electron microscopy (TEM) was used to visualize structural damage and bacteria within infected corneas. Results: Riboflavin-saturated corneas infected by S. aureus or P. aeruginosa (LT = 0.77% [0.41-1.87] and 0.81% [0.23, 1.46]) exhibited 3.18-fold and 3.02-fold lower LT values, respectively, than uninfected corneas (LT = 2.45% [2.15, 5.89]) (both P-values < 0.001). No LT difference was found between rose bengal–saturated corneas infected by S. aureus or P. aeruginosa and uninfected corneas (all LT values = 0.01% [0.01-0.01]; both P-values = 0.08). TEM showed bacteria on corneal stroma borders and occasionally inside the stroma. Conclusions: The results indicate that the amount of light arriving at the corneal endothelium is substantially reduced in infected corneas. The total fluence of clinical photoactivated chromophore for keratitis corneal crosslinking protocols can be safely increased substantially while maintaining a low risk of corneal endothelial damage.

Classical preoperative skin antisepsis is insufficient in completely eliminating bacterial skin colonization for arthroplasty. In contrast, photodynamic therapy (PDT) with red light and methyl-aminolevulinate (MAL), combined with skin antisepsis, led to the absence of bacterial growth in healthy participants, though with local skin erythema, posing an obstacle for orthopedic surgery. Therefore, we explored whether artificial daylight PDT (PDT-DL) was superior to red light. Twenty healthy participants were allocated to either 5-aminolevulinic acid-(5-ALA) PDT-DL (n = 10) or MAL-PDT-DL (n = 10) before antisepsis with povidone-iodine/alcohol. Skin swabs from the groin were taken to cultivate bacteria at baseline, after PDT-DL, and after the subsequent antisepsis. Additional swabs were taken on day 4 before and after antisepsis without PDT. The contralateral groin of each participant and of ten additional healthy volunteers served as the control (n = 30). In selected participants, 16S rRNA-based amplicon deep sequencing was performed. All participants showed a baseline bacterial colonization. After a PDT-DL with skin antisepsis, bacterial growth occurred in three (30%) and in one (10%) participants with 5-ALA and MAL, respectively, compared to the sixteen (55%) participants in the control group. On day 4, three (30%) participants per group showed positive cultures post antisepsis. Adverse effects were reported in six (60%) and zero (0%) participants for 5-ALA- and MAL-PDT-DL, respectively. The skin bacteriome changes correlated with the bacterial culture results. The MAL-PDT-DL with skin antisepsis significantly increased bacterial reduction on the skin without adverse effects. This offers an opportunity to prevent infections in arthroplasty patients and reduce antibiotic use, thus contributing to antibiotic stewardship goals emphasized in the One Health approach.

The rapid detection and species-level differentiation of bacterial pathogens facilitates antibiotic stewardship and improves disease management. Here, we develop a rapid bacteriophage-based diagnostic assay to detect the most prevalent pathogens causing urinary tract infections: Escherichia coli, Enterococcus spp., and Klebsiella spp. For each uropathogen, two virulent phages were genetically engineered to express a nanoluciferase reporter gene upon host infection. Using 206 patient urine samples, reporter phage-induced bioluminescence was quantified to identify bacteriuria and the assay was benchmarked against conventional urinalysis. Overall, E. coli, Enterococcus spp., and Klebsiella spp. were each detected with high sensitivity (68%, 78%, 87%), specificity (99%, 99%, 99%), and accuracy (90%, 94%, 98%) at a resolution of ≥10³ CFU/ml within 5 h. We further demonstrate how bioluminescence in urine can be used to predict phage antibacterial activity, demonstrating the future potential of reporter phages as companion diagnostics that guide patient-phage matching prior to therapeutic phage application.

Introduction: Streptococcus agalactiae, also known as group B streptococci (GBS), is associated with invasive infections in neonates. Identification of GBS vaginal colonization in pregnant women before delivery is essential for treatment with antibiotics to prevent intrapartum vertical transmission to the newborn. This study was designed to evaluate applicability of two rapid real‐time PCRs in comparison to standard culture identification.Material and methods: We compared the Xpert GBS assay, hereafter referred to as Xpert, and GenomEra GBS PCR, hereafter referred to as GenomEra. The standard culture identification consisted of two different agar plates as well as an enrichment broth.Results: We analyzed vaginal samples of 260 pregnant women; 42 samples were tested GBS‐positive by using standard culture as a gold standard, 30 by Xpert, and 37 by GenomEra. Xpert and GenomEra assays performed with sensitivities of 71.4% and 88.1% as well as specificities of 98.6% and 99.1%, respectively. Twelve vaginal samples were false‐negative by Xpert and five samples by GenomEra. Interestingly, three negative Xpert results of standard culture‐positive samples exhibited high Ct‐values indicating the presence of GBS. If higher Ct‐values are taken into consideration, the sensitivity of Xpert increases up to 78.6%. Moreover, only three Xpert PCRs had to be repeated, whereas two Genomera were invalid even after repetition and further 15 GenomEra PCRs were repeated because of borderline results or inhibition of the PCR test.Conclusions: In this study, GenomEra assay performed with a higher sensitivity than the Xpert PCR. On the other hand, the Xpert assay needs less hands‐on‐time for a sample preparation and requires approximately four‐fold less repetitions as compared to the GenomEra assay. This robust performance of the Xpert assay make it applicable as a rapid intrapartum point‐of‐care test, although a higher sensitivity would be desirable. Therefore, culture in the 35–37 week of gestation remains the gold standard to detect vaginal colonization.