Vlado Teodorovic

Effects of gluconodeltalactone and Lactobacillus plantarum on the production of histamine and tyramine in fermented sausages

Fermented sausages were made experimentally with addition of 0.3% (w/w) gluconodeltalactone (GDL) or a starter culture of Lactobacillus plantarum, unable to produce histamine or tyramine. Controls were produced without GDL and starter culture. During 15 days preparation and storage periods, number of bacteria and lactobacilli, pH, and levels of histamine, tyrosine and tyramine were monitored, and organoleptic evaluations were carried out. Maximal histamine levels were 19.41 micrograms/g of dry matter in the GDL-added sausages, 18.64 micrograms/g in the control, and 17.20 micrograms/g in the starter sausages. Maximal tyramine levels were 1249.16 micrograms/g in the GDL sausages, 1101.16 micrograms/g in the control, and 906.35 micrograms/g in the starter sausages. Sausages produced with GDL proved less acceptable in organoleptic evaluation due to an unpleasant sour flavour.

First report of Trichinella britovi in Serbia

In Europe, Serbia ranks among countries with a high prevalence of Trichinella infection in pigs, which continues to be a serious human health problem. While in some Balkan countries, more than one Trichinella species/genotype has been described in both the sylvatic and domestic cycles, these data are lacking for Serbia. To date, only a few Serbian isolates of Trichinella have been genetically specified, and all were classified as T. spiralis. Although transmission of Trichinella from domestic pigs to wildlife could be assumed, neither the infection status nor the species of Trichinella circulating among wildlife in Serbia has been investigated. This study shows the presence of two Trichinella species, T. spiralis and T. britovi, in wild animals originating from five districts in Serbia, where Trichinella infections in domestic pigs and humans have been recorded. Trichinella spiralis was detected in jackals (n = 3), red foxes (n = 2) and a wild cat (n = 1). We also established that wolves (n = 4) and red foxes (n = 2) serve as sylvatic reservoirs for T. britovi. This is the first report on the presence of T. britovi in Serbia.

A large-scale study of the Trichinella genus in the golden jackal (Canis aureus) population in Serbia.

Over the last decades the golden jackal (Canis aureus) has significantly expanded its range throughout Southeast and Central Europe, and the Balkan Peninsula is considered to be a core area of the species distribution in this part of the range. Due to its increasing number, ability of long distance movement through a wide range of landscapes and opportunistic feeding habits, the golden jackal may represent an important reservoir and transmitter of a variety of zoonotic agents, including parasites. The Balkans, Serbia included, remain an endemic area for various zoonotic parasites including Trichinella spp. Trichinella has recently been recorded in jackals in Serbia, which prompted us to carry out a large-scale survey of its prevalence, distribution and species identification in this host. In cooperation with local hunters, carcasses of a total of 738 legally hunted golden jackals were collected at 24 localities over an 11-year period (2003-2013). Analysis of tongue base tissue revealed Trichinella larvae in 122, indicating a prevalence of infection of 16.5%. No difference in the prevalence of infection was found between genders [16.2% in males and 16.9% in females (χ(2)=0.05, p=0.821)], or among the study years (G=7.22, p=0.705). Trichinella larvae were found in 13 out of the 24 examined localities. Molecular identification was performed for 90 isolates, and 64 (71.1%) larvae were identified as Trichinella spiralis and 25 (27.9%) as Trichinella britovi. Mixed infection (T. spiralis and T. britovi) was recorded in a single case. Although T. spiralis was more prevalent, T. britovi had a wider distribution, and was the only recorded species in jackal populations from the mountainous region of eastern Serbia. On the other hand, T. spiralis was dominant in jackals in the lowlands of central and northern Serbia, where domestic pigs are mostly reared. These results show that the golden jackal is involved in both the domestic and sylvatic cycle, and that it has emerged as a major host species in the sylvatic cycle of the Trichinella genus. Therefore, continued monitoring of Trichinella infection in golden jackals in Serbia and the whole of the Balkans is recommended in order to control transmission of this parasite to humans and domestic animals.

The Wolf (Canis lupus) as an Indicator Species for the Sylvatic Trichinella Cycle in the Central Balkans

Abstract Wildlife is the most important reservoir of Trichinella spp. worldwide. Although the Balkans are a recognized European endemic region for Trichinella infections, data on wildlife are scarce. To monitor the circulation of these zoonotic parasites in the Central Balkan region, the wolf (Canis lupus) was selected because of its abundance (>2,000 individuals) and because it is at the top of the food chain. A total of 116 carcasses of wolves were collected in Serbia and in the neighboring areas of Macedonia and Bosnia and Herzegovina (B&H) between 2006 and 2013. Trichinella spp. larvae were found in 54 (46.5%) wolves. The great majority (90.5%) originated from Serbia, where 52 of the 105 examined animals were Trichinella positive (49.5%; 95% confidence interval  = 39.9–59.1). One positive animal each was found in B&H and Macedonia. All larvae were identified as Trichinella britovi. The high prevalence of Trichinella infection in wolves suggests that this carnivore can be a good indicator species for the risk assessment of the sylvatic Trichinella cycle in the Central Balkans.

Environmental prevalence and persistence of Listeria monocytogenes in cold-smoked trout processing plants.

The presence of Listeria monocytogenes on the surfaces of equipment and worker’s hands during different production stages, as well as on fish skin and meat during processing and storage of cold-smoked trout, was investigated. Listeria monocytogenes was recovered from 10 (6.06%) of a total 165 cotton-swabbed samples collected from the surfaces of equipment and worker’s hands at two separate processing facilities. Of 105 samples collected from fish skin and meat during various production steps in both processing plants, 14 (13.33%) were confirmed culture-positive for L. monocytogenes, with recovery being most frequently in samples collected in the area before vacuum packaging. Recovery rates at two different Serbian processing plants did not differ (p<0.05), but suggested that different L. monocytogenes serotypes appeared to be resident within each processing plant and may have contributed to the final product contamination. From all smoked trout samples collected during 7, 14, 21 and 28 days of storage at 4oC only two were culture-positive for L. monocytogenes serotype 1/2a and both of these were collected on the 7th day of storage. Conversely, 4, 3 and 1 sample(s) were contaminated with L. monocytogenes serotypes 1/2a and 1/2b after 7, 14 and 21 days storage at 10oC. Listeria monocytogenes was not recovered from smoked trout stored 28 days at 10oC. Results emphasize the importance of adhering to strict hygienic and quality control standards throughout the processing environment.

Antibiotic Resistance and Molecular Studies on Salmonella Enterica Subspecies Enterica Serovar Infantis Isolated in Human Cases and Broiler Carcasses

Abstract During the year 2012 a study was conducted on the hygiene of the production of broiler carcasses at three abattoirs in the Republic of Serbia. A total of 150 samples of broiler neck skin were examined and 17 salmonella isolates were recorded. Isolates were, by using the corresponding monovalent and polyvalent sera, determined according to type as Salmonella enterica subspecies enterica serovar Infantis (S. Infantis 6, 7, r, 1, 5). In the case of the disease in humans, 5 Salmonella samples of identical serovars were isolated. After that, 22 samples were tested for antibiotic resistance by the disk diffusion test. Isolates showed resistance to ampicillin and nalidixic acid (95.5%), tetracycline (91%), cefotaxime/clavulanic acid (68.2%), but not to ciprofloxacin, gentamicin, and trimethoprim/sulfamethoxazole. The degree of genetic similarity of isolates from diseased humans and broiler carcasses was determined at a molecular level. Cluster analysis revealed the presence of 7 profiles, while all isolates have 92% genetic similarity. Although there are differences in the antimicrobial resistance of isolates originating from diseased humans and neck skin of tested broilers, can not be excluded an epidemiological link, because in the dominant genotype SINFXB0001, established in 8 isolates from diseased humans (3 isolates), and the neck skin of broilers (5 isolates), a genetic similarity of 100% was recorded. Based on these results, the presence of S. Infantis on broiler carcasses can be considered a hazard to human health. Abstract Tokom 2012. godine sprovedena su istraživanja higijene procesa proizvodnje trupova brojlera, na tri klanice u Republici Srbiji. Ispitano je 150 uzoraka kožica vrata brojlera i utvrđeno je 17 izolata salmonela. Izolati su, korišćenjem odgovarajućih monovalentnih i polivalentnih seruma, tipizovani kao Salmonella enterica subspecies enterica serovar infantis (S. Infantis 6, 7, r, 1, 5). U slučajevima oboljenja ljudi, izolovano je 5 uzoraka salmonele identičnog serovarijeteta. Nakon toga, na 22 uzorka, rađeno je ispitivanje antibiotske rezistencije izolata disk difuzionim testom. Izolati su pokazali rezistentnost prema: ampicilinu i nalidiksičnoj kiselini (95,5%), tetraciklinu (91%), cefotaksim/klavulanskoj kiselini (68,2%), ali ne i prema ciprofloksacinu, gentamicinu i trimetoprim/sulfametoksazolu (0%). Stepen genetske sličnosti izolata poreklom od obolelih ljudi i sa trupova brojlera je određen molekularnim metodama. Analiza klastera je pokazala prisustvo 7 profila, dok svi izolati imaju 92% ge netske sličnosti. Iako postoje razlike u antimikrobnoj rezistenciji izolata poreklom od obolelih ljudi i sa kožica vrata brojlera, ne može se isključiti epidemiološka povezanost, jer kod dominantnog genotipa SINFXB0001, utvrđenog kod 8 izolata poreklom od obolelih ljudi (3 izolata) i sa kožica vrata brojlera (5 izolata), postoji genetska sličnost od 100%. Na osnovu dobijenih rezultata, istraživanje je pokazalo da prisustvo S. Infantis na trupovima brojlera predstavlja hazard po zdravlje ljudi.

MRSA in pigs in Serbia

Meticilin-resistant Staphylococcus aureus (MRSA) primarily causes human infections; however, over the past several years pigs have been identified as a source of human MRSA infection in Europe ([EFSA 2009][1]). We undertook a study to sample pigs in Serbia for the presence of MRSA. A mid-scale,

The Influence of Pre-Mortem Conditions on Pale, Soft and Exudative (PSE) and Dark, Firm and Dry (DFD) Pork Meat

Abstract The aim of this study was to determine the effect of gender, stocking density in the transport vehicle, lairage time and season on the incidence of skin lesions on pig carcasses and PSE and DFD meat. Skin lesions on carcasses (480, in total) were assessed according to the Welfare Quality® protocol (2009). The pH and temperature measurements were performed 45 minutes after slaughter. The group of carcasses with skin lesions score 2 had significantly higher incidence of PSE and DFD meat compared to the groups of carcasses with skin lesions score 0 and 1. With regard to gender, there were no differences in meat quality parameters, as well as for the incidence of skin lesions and PSE and DFD meat. The results showed that a space allowance lower than 0.3 m2/100 kg and higher than 0.5 m2/100 kg pig had a detrimental effect to animal welfare and meat quality. Lairage time affected meat quality parameters, incidence of skin lesions score and PSE and DFD meat, where after long lairaging (> 17 h) mean pH45 and t45 values became significantly higher, as well as the incidence of skin lesions and DFD meat. After short lairaging (< 1 h) mean pH45 value became significantly lower, while mean t45 value and the incidence of PSE meat became significantly higher. A significantly higher number of skin lesions on the carcass were observed in winter compared to all other seasons. High temperatures during summer and low temperatures during winter had a negative influence on meat quality parameters and incidence of PSE and DFD meat.

Behavior of Salmonella typhimurium in pork minced meat and pork skin at different storage temperatures.

Salmonella is a common contaminant of pork and can present a health hazard to consumers. Therefore, for an effective control, the entire supply chain must be involved. The aim of this paper is to examine the survival of Salmonella Typhimurium in pork minced meat and skin at different temperatures and time. In minced meat, stored at +4 ± 0.5°C during 72 h, the number of Salmonella Typhimurium of all three examined strains A, B, and C decreased (p<0.01). In minced meat, stored at +10 ± 1°C after 72 h, the number of Salmonella strain A was significantly higher (p<0.01), while for strains B and C, no statistically significant difference was determined (p>0.05). On the skin, stored at +4 ± 0.5°C during 72 h, the number of Salmonella of strains A and B decreased (p<0.01), while for strain C, no statistically significant difference was determined (p>0.05). On the skin, stored at +10 ± 1°C during 72 h, the number of Salmonella of strains A and C decreased (p<0.01), while for strain B, no statistically significant difference was determined (p>0.05).

INVESTIGATION OF THE EFFICACY OF IMMUNOCASTRATION AIMED AT THE PREVENTION OF SEX ODOUR IN BOAR MEAT

Disadvantage of meat known as boar taint is caused by steroids, androstenone being of particular importance, as well as indole and its derivatives, among which the best known is skatole. The common practice in Europe, in order to control these changes in meat, is castration without anesthesia. This intervention causes pain and stress to animals, thus undermining animal welfare. Many countries considering animal welfare try to find the alternative solutions in order to avoid castration. The alternative to surgical castration and possible solution to the problem of sex odour in the meat, as well as androstenone and skatole contents decrease in the boars fat is immunological castration of boars (immunocastration). Average skatole content in fat tissue of boars was significantly higher (0.21±0.03 μg/g) compared to skatole content in fat tissue of the castrates, or immunocastrates (0.12±0.02 μg/g). In adipose tissue of the castrates and immunocastrates there was no significant difference in the average content of skatole. The content of androstenone in the adipose tissue of immunocastrates was below detection limits, and the average androstenone level in adipose tissue of boars was 0.66±0.13 μg/g. The obtained results show that immunocastration is justified in consideration of the meat quality and can completely replace castration in male animals, which is in compliance with the preservation of animal welfare in rearing fattening young boars.