Katalin Kristóf

Prof. Dr. Katalin Kristóf


Research Focus & Metrics

Academic Career Length

3Years (2024-Present)

(Calculated once Scilit publication data is synced: current year − year of first publication + 1)

Representative Publications

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2 December 2024 in Microorganisms
Verified
Journal Article
Open access
PDF file
David HummelDavid Hummel
David Hummel
JJJanos Juhasz
Janos Juhasz
KKKatalin Kamotsay
Katalin Kamotsay
KKKatalin Kristóf
Katalin Kristóf
BXBasil Britto Xavier
Basil Britto Xavier
BKBela Kocsis
Bela Kocsis
Multidrug-resistant Acinetobacter baumannii is a major concern in healthcare institutions worldwide. Several reports described the dissemination of A. baumannii high-risk clones that are responsible for a high number of difficult-to-treat infections. In our study, 19 multidrug-resistant A. baumannii strains from Budapest, Hungary, were investigated based on whole-genome sequencing (WGS). The obtained results were analysed together with data from 433 strains of A. baumannii from the Pathogenwatch database. WGS analysis of 19 A. baumannii strains detected that 12 belonged to ST2 and seven belonged to ST636. Among ST2 strains, 11 out of 12 carried either blaOXA-23 or blaOXA-58 genes; however, all strains of ST636 uniformly carried blaOXA-72 gene. All strains of ST2 and ST636 carried blaOXA-66 and blaADC-25 genes. Based on core genome multilocus sequence typing (cgMLST), 10 strains of ST2 belonged to cgMLST906, one strain to cgMLST458, and one strain to cgMLST1320; by contrast, all strains of ST636 belonged to cgMLST1178. Certain virulence determinants were present in all strains of both ST2 and ST636, namely, Ata, Bap, BfmRS, T2SS and PNAG. Interestingly, OmpA was present in all strains of ST2, but it was absent in all strains of ST636. Comparative analysis of 19 strains of this study and the collection of 433 isolates from Pathogenwatch database, proved a diverse clonal distribution of high-risk A. baumannii clones in Europe. The major clone in Europe is ST2, which is present all over the continent. However, ST636 has been mainly reported in Eastern Europe. Interestingly, cgMLSTs of ST2 correspond to the production of different beta-lactamases, namely, OXA-82 in cgMLST116, OXA-72 in cgMLST506, and cgMLST556, PER-1 in cgMLST456 and cgMLST1041. Our study demonstrates that the ST2 high-risk clone of A. baumannii is the most widespread in Europe; however, based on cgMLST analysis, a detailed detection of beta-lactamase production can be determined.

10 April 2026 in Pharmaceutics
Verified
Journal Article
Open access
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SAFAA OMERSAFAA OMER
SAFAA OMER
NNNandor Nagy
Nandor Nagy
JPJúlia Pongrácz
Júlia Pongrácz
BTBence Tóth
Bence Tóth
BPBalázs Pinke
Balázs Pinke
Romana ZelkoRomana Zelko
Romana Zelko
Background/Objectives: Fungal keratitis remains a vision-threatening infection, and current amphotericin B (AmphB) eye drops suffer from low corneal residence time, poor aqueous solubility, and the need for frequent dosing. This study develops electrospun nanofiber-based ophthalmic inserts combining polyvinyl alcohol (PVA), gamma-cyclodextrin (γ-CD), and sodium taurocholate (STC) to enhance AmphB solubility and provide a non-invasive, rapidly dissolving ophthalmic dosage form. Methods: γ-CD and STC-enhanced AmphB-loaded PVA nanofiber-based ophthalmic inserts with varying γ-CD and STC concentrations were prepared by electrospinning and characterized by scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FTIR), and X-ray diffraction (XRD). Drug content, in vitro release (Weibull modeling), antifungal activity against Candida albicans, Fusarium solani, and Aspergillus fumigatus, ocular cytocompatibility using the Hen’s Egg Test on Chorioallantoic Membrane (HET-CAM), and accelerated stability (40 ± 2 °C, 75 ± 5% relative humidity, 4 weeks) were evaluated. Results: Bead-free nanofibers with mean diameters between 216 ± 33 nm and 310 ± 35 nm were obtained, and XRD confirmed complete amorphization of AmphB within the PVA nanofiber matrix, forming an amorphous solid dispersion. All formulations showed rapid and nearly complete AmphB release (≈100% within 60 min), with Weibull β values < 0.75, indicating Fickian diffusion-controlled release. AmphB-loaded PVA nanofiber-based ophthalmic inserts produced inhibition zones and broth susceptibility profiles comparable to AmphB in dimethyl sulfoxide (DMSO), demonstrating preserved antifungal activity. HET-CAM scores (0–0.9) classified the inserts as practically non-irritant, and SEM/FTIR after accelerated storage showed no relevant morphological or physicochemical changes. Conclusions: These γ-CD and STC-enhanced AmphB-loaded PVA nanofiber-based ophthalmic inserts provide a non-invasive, rapidly dissolving ophthalmic dosage form that combines amorphous AmphB, immediate drug availability, and good ocular tolerance, supporting their further development as a patient-friendly treatment option for fungal keratitis.

4 May 2024 in Vaccines
Verified
Journal Article
Open access
PDF file
JHJudit Krisztina Horváth
Judit Krisztina Horváth
GTGergő Túri
Gergő Túri
KKKatalin Krisztalovics
Katalin Krisztalovics
KKKatalin Kristóf
Katalin Kristóf
Beatrix OrosziBeatrix Oroszi
Beatrix Oroszi
Hungary provides the opportunity to evaluate the effectiveness of COVID-19 vaccination in a setting where naturally acquired immunity and hybrid immunity are likely to play a greater role due to suboptimal vaccination coverage. Methods: A test-negative study was conducted during the 2022–2023 respiratory season at the primary care level to determine the effectiveness of at least one COVID-19 booster dose in preventing medically attended symptomatic RT-PCR-confirmed SARS-CoV-2 infection in adults. Unvaccinated patients were used as a reference group. Results: A total of 247 cases and 1073 controls were included in the analysis. CVE was 56.8% (95% CI: 11.9–78.8%) in the population aged 60 years and older and 2.3% (95% CI: −50.0–36.3%) in the younger adults against COVID-19 caused by Omicron subvariants, mainly BA.5, BQ.1, and XBB.1. Self-reported COVID-19 in the 60–365 days prior to the current illness did not confer protection against reinfection without vaccination, but together with booster vaccination, it reduced the risk of COVID-19 by 63.0% (95% CI: −28.0–89.3%) and 87.6% (95% CI: 26.4–97.9%) among the 18–59 and 60+ age groups, respectively. Conclusions: CVE against COVID-19 was moderately high in the 60+ age groups. Because of the benefit of hybrid immunity, persons with previous SARS-CoV-2 infection should still be considered for vaccination campaigns.

2 April 2026 in Preprints.org
Verified
Preprint
Open access
PDF file
BSBalazs Sax
Balazs Sax
AKAdam Koppanyi
Adam Koppanyi
KKKatalin Kristóf
Katalin Kristóf
ÁKÁkos Király
Ákos Király
GPGyula Prinz
Gyula Prinz
BMBela Merkely
Bela Merkely
Percutaneous cable infection of left ventricular assist device (LVAD) patients is a significant source of morbidity, often caused by biofilm producing or multidrug resistant bacteria. We hypothesized that bacteriophage viruses can be identified from biological samples of patients with active driveline infection. Six patients with local percutaneous lead infections were enrolled. Microbiological samples were collected from the infected wound and other skin regions. The isolated viral strains and phages from wastewater samples were then tested against the pathogen bacterial cultures in vitro. Biofilm disruption assay and genetic analysis of the strains were also performed. Bacteriophages with lytic activity could be identified from samples of two patients. One patient contained four strains showing strong efficacy against his own Staphylococcus epidermidis. Furthermore, this bacterium was susceptible to phages identified from another patient and strains from wastewater samples. Genomic analysis suggested lysogenic lifestyle of the phages. However, none of them have shown any microbiological signs of lysogeny. In conclusion, we have been able to prove in vitro lytic activity of bacteriophages originating from the same LVAD patient. We also found effective phages in biological samples of other patients and wastewater samples, suggesting that patients implanted in the same center may share bacteriophage flora.

30 April 2026 in Viruses
Verified
Journal Article
Open access
PDF file
BSBalazs Sax
Balazs Sax
AKAdam Koppanyi
Adam Koppanyi
KKKatalin Kristóf
Katalin Kristóf
ÁKÁkos Király
Ákos Király
GPGyula Prinz
Gyula Prinz
BMBela Merkely
Bela Merkely
Percutaneous cable infection of left ventricular assist device (LVAD) patients is a significant source of morbidity, often caused by biofilm-producing or multidrug-resistant bacteria. We hypothesized that bacteriophage viruses can be identified from biological samples of patients with active driveline infection. Six patients with local percutaneous lead infections were enrolled. Microbiological samples were collected from the infected wound and other skin regions. The isolated viral strains and phages from wastewater samples were then tested against the pathogen bacterial cultures in vitro. Biofilm disruption assay and genetic analysis of the strains were also performed. Bacteriophages with lytic activity could be identified from samples of two patients. One patient contained four strains showing strong efficacy against his own Staphylococcus epidermidis. Furthermore, this bacterium was susceptible to phages identified from another patient and strains from wastewater samples. Genomic analysis suggested lysogenic lifestyle of the phages. However, none of them have shown any microbiological signs of lysogeny. In conclusion, we have been able to prove in vitro lytic activity of bacteriophages originating from the same LVAD patient. We also found effective phages in biological samples of other patients and wastewater samples, suggesting that patients implanted in the same center may share bacteriophage flora.

13 April 2026 in Vaccines
Verified
Journal Article
Open access
PDF file
GTGergő Túri
Gergő Túri
VVViktória Velkey
Viktória Velkey
KMKrisztina Juhász Mucsányiné
Krisztina Juhász Mucsányiné
KKKatalin Krisztalovics
Katalin Krisztalovics
AFAnnamária Ferenczi
Annamária Ferenczi
Beatrix OrosziBeatrix Oroszi
Beatrix Oroszi
Background: The 2024/25 influenza season in Hungary experienced a major surge in cases, the largest since the COVID-19 pandemic. We evaluated influenza vaccine effectiveness (VE) in primary care settings among adults and vaccination target groups, and also according to time since vaccination, prior seasonal vaccination, and influenza type. Methods: A test-negative case–control study was conducted in Hungary. Data and specimens were collected from primary care patients with an acute respiratory infection (ARI). Patients with positive PCR test results for influenza were classified as cases, while those with negative test results for influenza were classified as controls. Adjusted VEs were calculated using logistic regression as (1 − odds ratio of vaccination) × 100. Results: Between November 2024 and May 2025, 2074 patients were included in the analysis, of whom 395 cases had influenza. Of the 129 vaccinated patients, 123 (95%) received trivalent inactivated adjuvanted whole-cell vaccine (TIAV), and 6 (5%) received quadrivalent split-virion vaccine. The VE against any influenza was 53% (95% CI: 13–74) in the 18+ age group and 52% (95% CI: 7–75) in the target group for vaccination. The VE against any influenza was 63% (95% CI: 17–84) 14–89 days after vaccination, and 27% (95% CI: −67–68) 90 days or more after vaccination. The VE against any influenza was 56% (95% CI: 1–80) with both current and prior seasonal vaccination, and 5% (95% CI: −64–45) with only prior seasonal vaccination. The VE against influenza A was 39% (95% CI: −16–68), and against influenza B was 80% (95% CI: 2–96). Conclusions: We observed moderate vaccine effectiveness against any influenza, with higher protection within three months after vaccination. Our research findings provide evidence to inform the development of vaccines and the scheduling of vaccination campaigns, with the aim of maximizing the level of protection provided by vaccines throughout the entire influenza season.