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Query: "author" (Tomič Viktorija) .

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Bronchial bacterial colonization and the susceptibility of isolated bacteria in patients with lung malignancy
Bojana Beović, Viktorija Tomič, Marko Bitenc, Mateja Marc-Malovrh, Vladimir Dimitrić, Dane Lužnik, Martina Miklavčič, Tamara Božič, Tina Gabrovec, Aleksander Sadikov, Aleš Rozman, 2025, original scientific article

Abstract: Background Postoperative pneumonia (POP) remains a leading cause of mortality following lung surgery. Recent studies have confirmed that the respiratory tract below the vocal cords is not sterile and often harbours potentially pathogenic microorganisms (PPMs), putting patients with lung malignancies at an increased risk for pulmonary infections. Patients and methods The study analysed 149 patients who underwent bronchoscopy for lung lesions suspected to be lung cancer. Protected specimen brush (PSB) samples were obtained during bronchoscopy prior to any specific treatment. Bacterial identification and antimicrobial susceptibility testing were conducted on the isolated strains. Results Bacterial colonization was detected in 88.6% of patients, with 21.5% carrying PPMs. Notably, patients with type 2 diabetes exhibited a higher rate of PPM colonization compared to others. Antibiotic susceptibility testing showed no significant differences in efficacy between amoxicillin with clavulanic acid and first-generation cephalosporin in both colonized patients and those with PPMs. Importantly, no multidrug-resistant bacteria were identified. Conclusions Our findings indicate a slightly lower PPM colonization rate compared to previous studies, possibly due to the unique geographic characteristics of the study population. The absence of significant differences in bacterial susceptibility between the two tested antibiotics highlights the need for further research to refine perioperative infection management strategies.
Keywords: bronchial bacterial colonization, potentially pathogenic microorganisms, antibiotic prophylaxis
Published in DiRROS: 03.06.2025; Views: 586; Downloads: 295
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3.
Development of novel digital PCR assays for the rapid quantification of Gram-negative bacteria biomarkers using RUCS algorithm
Alexandra Bogožalec Košir, Špela Alič, Viktorija Tomič, Dane Lužnik, Tanja Dreo, Mojca Milavec, 2024, original scientific article

Abstract: Rapid and accurate identification of bacterial pathogens is crucial for effective treatment and infection control, particularly in hospital settings. Conventional methods like culture techniques and MALDI-TOF mass spectrometry are often time-consuming and less sensitive. This study addresses the need for faster and more precise diagnostic methods by developing novel digital PCR (dPCR) assays for the rapid quantification of biomarkers from three Gram-negative bacteria: Acinetobacter baumannii, Klebsiella pneumoniae, and Pseudomonas aeruginosa. Utilizing publicly available genomes and the rapid identification of PCR primers for unique core sequences or RUCS algorithm, we designed highly specific dPCR assays. These assays were validated using synthetic DNA, bacterial genomic DNA, and DNA extracted from clinical samples. The developed dPCR methods demonstrated wide linearity, a low limit of detection (approx. 30 copies per reaction), and robust analytical performance with measurement uncertainty below 25 %. The assays showed high repeatability and intermediate precision, with no cross-reactivity observed. Comparison with MALDI-TOF mass spectrometry revealed substantial concordance, highlighting the methods’ suitability for clinical diagnostics. This study underscores the potential of dPCR for rapid and precise quantification of Gram-negative bacterial biomarkers. The developed methods offer significant improvements over existing techniques, providing faster, more accurate, and SI-traceable measurements. These advancements could enhance clinical diagnostics and infection control practices.
Keywords: digital PCR (dPCR), Gram-negative bacteria, pathogen detection, respiratory infections, biomarkers, RUCS algorithm
Published in DiRROS: 05.11.2024; Views: 843; Downloads: 721
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4.
Nephila spider male aggregation : preference for optimal female size and web clustering
Matjaž Kuntner, Maj Kuntner, Eva Kuntner, Alexandra Bogožalec Košir, Irena Kuntner, Viktorija Tomič, Jana Faganeli Pucer, Erik Štrumbelj, Daiqin Li, 2024, original scientific article

Abstract: Sexual size dimorphism theory predicts biased operational sex ratios (OSRs) and an uneven distribution of males among certain females. We studied this phenomenon through a field census of the giant wood spider Nephila pilipes (family Nephilidae) in Singapore, a species where females are, on average, 6.9 times larger than males. Specifically, we tested two hypotheses concerning male distribution, given their tendency to aggregate in certain female webs. The optimal female size hypothesis predicts that males would predominantly occupy webs of intermediate-sized females. The web clustering hypothesis posits that more males would be found in webs closer together compared to those farther apart. Our snapshot census revealed a female-biased OSR (females: males = 1.85) with an uneven distribution of males in female webs. Most males were found in webs of intermediate-sized females aligning with the optimal female size hypothesis. Proximity among female webs was indicative of male presence, lending support to the web clustering hypothesis. While our study's limited sample size warrants caution, we conclude that in N. pilipes, male occupation of female webs is facilitated by the clustering of webs, and males prefer to cohabit with optimally sized, receptive females.
Keywords: sexual size dimorphism, operational sex ratios (OSRs), male distribution, optimal female size hypothesis, web clustering hypothesis, female-biased OSR, intermediate-sized females, proximity of webs, male aggregation, arachnology, behavioral ecology, environmental zoology
Published in DiRROS: 03.09.2024; Views: 927; Downloads: 638
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Metrological evaluation of DNA extraction method effects on the bacterial microbiome and resistome in sputum
Aleksander Benčič, Nataša Toplak, Simon Koren, Alexandra Bogožalec Košir, Mojca Milavec, Viktorija Tomič, Dane Lužnik, Tanja Dreo, 2024, original scientific article

Abstract: Targeted high-throughput sequencing (HTS) has revolutionized the way we look at bacterial communities. It can be used for the species-specific detection of bacteria as well as for the determination of the microbiome and resistome and can be applied to samples from almost any environment. However, the results of targeted HTS can be influenced by many factors, which poses a major challenge for its use in clinical diagnostics. In this study, we investigated the impact of the DNA extraction method on the determination of the bacterial microbiome and resistome by targeted HTS using principles from metrology and diagnostics such as repeatability and analytical sensitivity. Sputum samples spiked with Acinetobacter baumannii, Klebsiella pneumoniae, and Pseudomonas aeruginosa at three different concentrations (103–106 cells/mL) were used. DNA was extracted from each sample on 2 separate days in three replicates each using three different extraction methods based on cetrimonium bromide, magnetic beads, and silica membranes. All three spiked bacteria were detected in sputum, and the DNA extraction method had no significant effect on detection. However, the DNA extraction method had significant effects on the composition of the microbiome and the resistome. The sequencing results were repeatable in the majority of cases. The silica membrane-based DNA extraction kit provided the most repeatable results and the highest diversity of the microbiome and resistome. Targeted HTS has been shown to be a reliable tool for determining the microbiome and resistome; however, the method of DNA extraction should be carefully selected to minimize its impact on the results.
Keywords: targeted high-throughput sequencing, bacterial microbiome, resistome, bacteria detection, DNA extraction, metrology, diagnostics, repeatability
Published in DiRROS: 30.08.2024; Views: 1142; Downloads: 721
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6.
Survey results on nucleic acid tests of infectious diseases : present status and need for rapid and near-patient diagnostics
Jörg Neukammer, Martin Hussels, Andreas Kummrow, Alison S. Devonshire, Carole A. Foy, Jim F. Huggett, Helen C. Parkes, Jana Žel, Mojca Milavec, Heinz Schimmel, Wolfgang Unger, Müslüm Akgöz, Timothy D. McHugh, Viktorija Tomič, Hans-Peter Grunert, Heinz Zeichhardt, 2015, original scientific article

Abstract: This survey discusses current and emerging isothermal and rapid polymerase chain reaction (PCR) based nucleic acid amplification methods for near-patient diagnostics. To assess the clinical need of rapid diagnostics for infectious diseases based on nucleic acid tests (NATs) we performed and analysed a questionnaire among laboratories participating in corresponding INSTAND ring trials for external quality assurance. The questions concerning new amplification technologies like isothermal nucleic acid amplification, potentially suited to significantly decrease turnaround times, were complemented by questions to evaluate the present status of NATs. Besides end-users, companies were also addressed by sending out a manufacturer specific questionnaire. Analysis of the answers from 48 laboratories in 14 European countries revealed that a much shorter turnaround time is requested for selected pathogens compared to about 2 h or longer when applying temperature cycling amplification, i.e. PCR. In this context, most frequently mentioned were methicillin-resistant Staphylococcus aureus (MRSA), norovirus, influenza A and B viruses, cytomegalovirus (CMV) as well as hepatitis B virus (HBV) and hepatitis C virus (HCV). At present, 8% of the laboratories having participated in this survey apply isothermal amplification of nucleic acids to identify infectious pathogens.
Keywords: nucleic acid tests, infectious diseases, virus detection, bacteria detection, isothermal nucleic acid amplification, status report, questionnaire, NAT, PCR
Published in DiRROS: 26.07.2024; Views: 1290; Downloads: 752
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7.
Evaluation of DNA extraction methods for reliable quantification of Acinetobacter baumannii, Klebsiella pneumoniae, and Pseudomonas aeruginosa
Alexandra Bogožalec Košir, Dane Lužnik, Viktorija Tomič, Mojca Milavec, 2023, original scientific article

Abstract: Detection and quantification of DNA biomarkers relies heavily on the yield and quality of DNA obtained by extraction from different matrices. Although a large number of studies have compared the yields of different extraction methods, the repeatability and intermediate precision of these methods have been largely overlooked. In the present study, five extraction methods were evaluated, using digital PCR, to determine their efficiency in extracting DNA from three different Gram-negative bacteria in sputum samples. The performance of two automated methods (GXT NA and QuickPick genomic DNA extraction kit, using Arrow and KingFisher Duo automated systems, respectively), two manual kit-based methods (QIAamp DNA mini kit; DNeasy UltraClean microbial kit), and one manual non-kit method (CTAB), was assessed. While GXT NA extraction kit and the CTAB method have the highest DNA yield, they did not meet the strict criteria for repeatability, intermediate precision, and measurement uncertainty for all three studied bacteria. However, due to limited clinical samples, a compromise is necessary, and the GXT NA extraction kit was found to be the method of choice. The study also showed that dPCR allowed for accurate determination of extraction method repeatability, which can help standardize molecular diagnostic approaches. Additionally, the determination of absolute copy numbers facilitated the calculation of measurement uncertainty, which was found to be influenced by the DNA extraction method used.
Keywords: nucleic acid, dPCR, DNA extraction methods, Gram-negative bacteria
Published in DiRROS: 12.07.2024; Views: 1179; Downloads: 723
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8.
The effects of topical antibiotics on eradication and acquisition of third-generation cephalosporin and carbapenem-resistant Gram-negative bacteria in ICU patients : ǂa ǂpost hoc analysis from a multicentre cluster-randomized trial
Nienke L. Plantinga, Bastiaan H. Wittekamp, Christian Brun-Buisson, Marc J. M. Bonten, 2020, original scientific article

Abstract: Objectives: The aim was to quantify the effects of selective digestive tract decontamination (SDD) consisting of a mouth paste and gastro-enteral suspension, selective oropharyngeal decontamination with a mouth paste (SOD) and 1-2% chlorhexidine (CHX) mouthwash on eradication and acquisition of carriage of third-generation cephalosporin-resistant Enterobacterales (3GCR-E) and carbapenem-resistant Gram-negative bacteria (CR-GNB) in Intensive Care Unit (ICU) patients. Methods: This was a nested cohort study within a cluster-randomized cross-over trial in six European countries and 13 ICUs with 8665 patients. Eradication and acquisition during ICU stay of 3GCR-E and CRGNB were investigated separately in the rectum and respiratory tract for the three interventions and compared with standard care (SC) using Cox-regression competing events analyses. Results: Adjusted cause specific hazard ratios (CSHR) for eradication of rectal carriage for SDD were 1.76 (95% CI 1.31-2.36) for 3GCR-E and 3.17 (95% CI 1.60-6.29) for CR-GNB compared with SC. For the respiratory tract, adjusted CSHR for eradication of 3GCR-E were 1.47 (0.98-2.20) for SDD and 1.38 (0.92-2.06) for SOD compared with SC, and for eradication of CR-GNB these were 0.77 (0.41-1.45) for SDD and 0.81 (0.44-1.51) for SOD, compared with SC. Adjusted CSHRs for acquisition of rectal carriage during SDD (compared with SC) were 0.51 (0.40-0.64) for 3GCR-E and of 0.56 (0.40-0.78) for CR-GNB. Adjusted CSHRs for acquiring respiratory tract carriage with 3GCR-E compared with SC were 0.38 (0.28-0.50) for SDD and 0.55 (0.42-0.71) for SOD, and for CR-GNB 0.46 (0.33-0.64) during SDD and 0.60 (0.44-0.81) during SOD, respectively. SOD was not associated with eradication or acquisition of 3GCR-E and CR-GNB in the rectum. Conclusions: Among mechanically ventilated ICU patients, SDD was associated with more eradication and less acquisition of 3GCR-E and CR-GNB in the rectum than SC. SDD and SOD were associated with less acquisition of both 3GCR-E and CR-GNB than SC in the respiratory tract.
Keywords: intensive care units -- analysis -- epidemiology, bacterial drug resistance, anti-infective agents -- therapeutic use decontamination, beta-lactamases, Gram-negative bacteria, gastrointestinal tract -- microbiology -- drug therapy, cohort studies, colonization, ESBL, digestive tract
Published in DiRROS: 27.05.2022; Views: 1789; Downloads: 640
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9.
Robust saliva-based RNA extraction-free one-step nucleic acid amplification test for mass SARS-CoV-2 monitoring
Eva Rajh, Tina Šket, Arne Praznik, Petra Sušjan, Alenka Šmid, Dunja Urbančič, Irena Mlinarič-Raščan, Polona Kogovšek, Tina Demšar, Mojca Milavec, Katarina Prosenc, Žiga Jensterle, Mihaela Zidarn, Viktorija Tomič, Gabriele Turel, Tatjana Lejko-Zupanc, Roman Jerala, Mojca Benčina, 2021, original scientific article

Abstract: Early diagnosis with rapid detection of the virus plays a key role in preventing the spread of infection and in treating patients effectively. In order to address the need for a straightforward detection of SARS-CoV-2 infection and assessment of viral spread, we developed rapid, sensitive, extraction-free one-step reverse transcription-quantitative polymerase chain reaction (RT-qPCR) and reverse transcription loop-mediated isothermal amplification (RT-LAMP) tests for detecting SARS-CoV-2 in saliva. We analyzed over 700 matched pairs of saliva and nasopharyngeal swab (NSB) specimens from asymptomatic and symptomatic individuals. Saliva, as either an oral cavity swab or passive drool, was collected in an RNA stabilization buffer. The stabilized saliva specimens were heat-treated and directly analyzed without RNA extraction. The diagnostic sensitivity of saliva-based RT-qPCR was at least 95% in individuals with subclinical infection and outperformed RT-LAMP, which had at least 70% sensitivity when compared to NSBs analyzed with a clinical RT-qPCR test. The diagnostic sensitivity for passive drool saliva was higher than that of oral cavity swab specimens (95% and 87%, respectively). A rapid, sensitive one-step extraction-free RT-qPCR test for detecting SARS-CoV-2 in passive drool saliva is operationally simple and can be easily implemented using existing testing sites, thus allowing high-throughput, rapid, and repeated testing of large populations. Furthermore, saliva testing is adequate to detect individuals in an asymptomatic screening program and can help improve voluntary screening compliance for those individuals averse to various forms of nasal collections.
Keywords: SARS-CoV-2, COVID-19, COVID-19 serological testing, real-time polymerase chain reaction, saliva, oral cavity swab, passive drool, pooling
Published in DiRROS: 09.11.2021; Views: 2291; Downloads: 980
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10.
Temporal changes in the epidemiology, management, and outcome from acute respiratory distress syndrome in European intensive care units : a comparison of two large cohorts
Yasser Sakr, Bruno François, Jordi Solé-Violan, Katarzyna Kotfis, Ulrich Jaschinski, Angel Estella, Marc Leone, Stephan M. Jakob, Xavier Wittebole, Luis E. Fontes, Viktorija Tomič, 2021, original scientific article

Abstract: Background. Mortality rates for patients with ARDS remain high. We assessed temporal changes in the epidemiology and management of ARDS patients requiring invasive mechanical ventilation in European ICUs. We also investigated the association between ventilatory settings and outcome in these patients. Methods. This was a post hoc analysis of two cohorts of adult ICU patients admitted between May 1–15, 2002 (SOAP study, n = 3147), and May 8–18, 2012 (ICON audit, n = 4601 admitted to ICUs in the same 24 countries as the SOAP study). ARDS was defined retrospectively using the Berlin definitions. Values of tidal volume, PEEP, plateau pressure, and FiO2 corresponding to the most abnormal value of arterial PO2 were recorded prospectively every 24 h. In both studies, patients were followed for outcome until death, hospital discharge or for 60 days. Results. The frequency of ARDS requiring mechanical ventilation during the ICU stay was similar in SOAP and ICON (327[10.4%] vs. 494[10.7%], p = 0.793). The diagnosis of ARDS was established at a median of 3 (IQ: 1–7) days after admission in SOAP and 2 (1–6) days in ICON. Within 24 h of diagnosis, ARDS was mild in 244 (29.7%), moderate in 388 (47.3%), and severe in 189 (23.0%) patients. In patients with ARDS, tidal volumes were lower in the later (ICON) than in the earlier (SOAP) cohort. Plateau and driving pressures were also lower in ICON than in SOAP. ICU (134[41.1%] vs 179[36.9%]) and hospital (151[46.2%] vs 212[44.4%]) mortality rates in patients with ARDS were similar in SOAP and ICON. High plateau pressure (> 29 cmH2O) and driving pressure (> 14 cmH2O) on the first day of mechanical ventilation but not tidal volume (> 8 ml/kg predicted body weight [PBW]) were independently associated with a higher risk of in-hospital death. Conclusion. The frequency of and outcome from ARDS remained relatively stable between 2002 and 2012. Plateau pressure > 29 cmH2O and driving pressure > 14 cmH2O on the first day of mechanical ventilation but not tidal volume > 8 ml/kg PBW were independently associated with a higher risk of death. These data highlight the continued burden of ARDS and provide hypothesis-generating data for the design of future studies.
Keywords: respiratory insufficiency, artificial respiration, tidal volume, airway pressures, driving pressure
Published in DiRROS: 16.06.2021; Views: 3140; Downloads: 1329
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