VESNA JAKI TKALEC

Dr. VESNA JAKI TKALEC

orcid

Research Focus & Metrics

Academic Career Length

12Years (2015-Present)

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

Representative Publications

View All Publications
31 March 2021 in Microorganisms
Verified
Journal Article
Open access
PDF file
LCLuka Cvetnić
Luka Cvetnić
MSMarko Samardžija
Marko Samardžija
SDSanja Duvnjak
Sanja Duvnjak
BHBoris Habrun
Boris Habrun
MCMarija Cvetnić Cvetnić
Marija Cvetnić Cvetnić
MBMiroslav Benić
Miroslav Benić
Background: The bacterial species S. aureus is the most common causative agent of mastitis in cows in most countries with a dairy industry. The prevalence of infection caused by S. aureus ranges from 2% to more than 50%, and it causes 10–12% of all cases of clinical mastitis. Aim: The objective was to analyze 237 strains of S. aureus isolated from the milk of cows with subclinical mastitis regarding the spa, mecA, mecC and pvl genes and to perform spa and multi-locus sequence typing (MLST). Methods: Sequencing amplified gene sequences was conducted at Macrogen Europe. Ridom StaphType and BioNumerics software was used to analyze obtained sequences of spa and seven housekeeping genes. Results: The spa fragment was present in 204 (86.1%) of strains, while mecA and mecC gene were detected in 10 strains, and the pvl gene was not detected. Spa typing successfully analyzed 153 tested isolates (64.3%), confirming 53 spa types, four of which were new types. The most frequent spa type was t2678 (14%). MLST typed 198 (83.5%) tested strains and defined 32 different allele profiles, of which three were new. The most frequent allele profile was ST133 (20.7%). Six groups (G) and 15 singletons were defined. Conclusion: Taking the number of confirmed spa types and sequence types (STs) into account, it can be concluded that the strains of S. aureus isolated from the milk of cows with subclinical mastitis form a heterogenous group. To check the possible zoonotic potential of isolates it would be necessary to test the persons and other livestock on the farms.

7 January 2021 in Toxins
Verified
Journal Article
Open access
PDF file
MKMaja Kiš
Maja Kiš
Ana VulicAna Vulic
Ana Vulic
Nina KudumijaNina Kudumija
Nina Kudumija
BSBojan Sarkanj
Bojan Sarkanj
VTVESNA JAKI TKALEC
VESNA JAKI TKALEC
Jelka PleadinJelka Pleadin
Jelka Pleadin
To investigate into the T-2 and HT-2 toxin occurrence, 240 samples of unprocessed cereals (maize, wheat, barley, and oats) were sampled from different fields located in three Croatian regions during 2017–2018. In all samples, sum concentrations of T-2/HT-2 toxin were determined using the ELISA method, while the LC-MS/MS was used as a confirmatory method for both mycotoxins in positive samples (>LOD) and the establishment of T-2 over HT-2 toxin ratios. The results showed oats to be the most contaminated cereal, with T-2/HT-2 toxins detected in 70.0% of samples, followed by barley (40.9%), maize (26.8%) and wheat (19.2%), with the mean T-2/HT-2 ratio ranging from 1:2.7 in maize to 1:4.4 in oats. Sum T-2/HT-2 concentrations in two maize samples were higher than the indicative level recommended by the European Commission, necessitating subsequent investigations into the conditions under which these poorly investigated mycotoxins are produced. Statistically significantly (p < 0.05) higher concentrations of T-2/HT-2 toxin were determined in oats throughout study regions as compared to those found in wheat, but not maize and barley, while the concentrations of these mycotoxins were related to the regional weather in Croatia.

22 September 2023 in International Journal of Food Microbiology
Verified
Journal Article
Closed access
Manuela ZadravecManuela Zadravec
Manuela Zadravec
TLTina Lešić
Tina Lešić
Dragan BrnićDragan Brnić
Dragan Brnić
Jelka PleadinJelka Pleadin
Jelka Pleadin
BKBart Kraak
Bart Kraak
JHJos Houbraken
Jos Houbraken

5 June 2026 in Toxins
Verified
Journal Article
Open access
PDF file
SFSanja Furmeg
Sanja Furmeg
VTVESNA JAKI TKALEC
VESNA JAKI TKALEC
Manuela ZadravecManuela Zadravec
Manuela Zadravec
Ana VulicAna Vulic
Ana Vulic
Fusarium mycotoxins pose a major challenge for agriculture and the food industry due to their frequent occurrence in cereals. In addition to conventional mycotoxins, modified mycotoxins, including the subgroup of masked mycotoxins, are receiving increasing attention. These compounds are formed through plant defence mechanisms, food processing or biological transformations and are often undetectable using conventional analytical methods. Due to their potential reactivation in the digestive system of humans and animals, masked mycotoxins represent a hidden threat to food safety. This article examines the mechanisms of formation of modified mycotoxins, their occurrence in the food chain and their potential health risks. Particular emphasis is placed on the analytical methods required for their detection, including advanced chromatographic and spectrometric techniques. Understanding modified mycotoxins is crucial for the development of more effective control and prevention strategies. Improved agronomic practices, proper storage and advances in detection methods are essential to reduce exposure to these compounds and ensure food safety. This study provides a comprehensive overview of the current state of research on modified mycotoxins and underlines the need for further scientific research and regulatory guidance to protect consumer health and maintain confidence in the food industry.

11 November 2015 in Mljekarstvo
Verified
Journal Article
Open access
PDF file
VIVeterinarski zavod Križevci Hrvatski veterinarski institut
Veterinarski zavod Križevci Hrvatski veterinarski institut
VTVESNA JAKI TKALEC
VESNA JAKI TKALEC
DMDarko Majnarić
Darko Majnarić
JJJadranka Jurmanović
Jadranka Jurmanović
BHBoris Habrun
Boris Habrun
BMBranka Šeol Martinec
Branka Šeol Martinec
The physiological properties of 47 Staphylococcus aureus strains were investigated. The test strains were grown on bacteriological media and identified by the ID32 STAF system for biochemical identification of bacteria. Sensitivity to antimicrobial agents was performed by the disc diffusion method. The nuc gene and the virulence factors coa, hla, hlb, hld, hlg, hlg-2, tst, eta, etb, lukF-PV and lukS-PV and mecA gene were detected by the polymerase chain reaction. Furthermore, the spa type of the studied isolates was also set. According to the obtained results, all strains had the nuc, coa, hla and hld gene. Ten strains (21.3 %) had also the tst gene, while 37 strains (78.7 %) had the hlg gene and 35 strains (74.5 %) had the hlb and hlg-2 genes. All of the investigated S. aureus isolates were penicillin resistant (100 %), with 29 strains which were also resistant to oxacillin (61.7 %). Methicillin (oxacillin) resistance was detected by the mecA gene detection, which is also the first MRSA result from the secretion samples of cows’ mammary glands in Croatia. The researched MRSA strains proved to belong to different spa types, and the most common were spa types t005, t011 and t521, and a new spa type t9498 was detected.

24 July 2025 in Applied Sciences
Verified
Journal Article
Open access
PDF file
DLDarija Bendelja Ljoljić
Darija Bendelja Ljoljić
MBMelita Boroša
Melita Boroša
Ivica KosIvica Kos
Ivica Kos
LCLuka Cvetnić
Luka Cvetnić
Ivan VnučecIvan Vnučec
Ivan Vnučec
VTVESNA JAKI TKALEC
VESNA JAKI TKALEC
Following hygiene standards in milk production is essential for making high-quality sour cream, especially when using traditional methods that rely on raw milk. The aim of this study was to determine the physicochemical, microbiological, and sensory quality of artisanal sour cream samples collected from major marketplaces in the wider Zagreb area. On average, the samples contained 27.99% milk fat, 3.30% protein, 34.29% dry matter, 6.51% fat-free dry matter and 3.00% lactose, with considerable variability observed across all components. Microbiological analysis revealed the presence of Staphylococcus aureus in 35.30% of the samples, Enterobacteriaceae in 76.47%, Escherichia coli in 94.11%, Bacillus spp. in 23.53%, and yeasts in 100% of the samples. Listeria monocytogenes and Salmonella spp. were not detected. The sensory analysis of the textural properties showed significant variability in firmness, adhesiveness, viscosity, creaminess, and fizziness. Samples with higher milk fat and dry matter content were rated better for creaminess, viscosity and mouth firmness. Flavour assessments, particularly for cream and diacetyl notes, also varied widely among samples. These findings highlight the complexity of sour cream’s sensory attributes and the significant influence of ingredient composition and processing techniques on appearance, aroma, texture, taste, and flavour. Principal component analysis (PCA) with Varimax rotation simplified the data structure and identified key dimensions of quality variation. Principal component analysis (PCA) revealed that the first principal component (PC1) effectively discriminated the cream samples based on sensory attractiveness and indicators of spoilage and highlighted the association between off-flavour and microbial contamination with inferior characteristics. The second principal component (PC2) captured the differences in physicochemical characteristics and showed a gradient from richer, creamier samples with higher fat content to those with lower acidity and higher freshness.