Rezistencija na tetraciklin bakterija mlečne kiseline izolovanih iz tradicionalnih sireva Srbije

Food chain may represent a possible route for the transmission of antibiotic resistant bacteria between human and animal populations. Commensal bacteria originating from food-producing animals can contaminate food and by that means become a part of the complex food microbiota. Commensal bacteria can also serve as reservoirs for the antibiotic resistance genes. Tetracycline resistance in commensal bacteria is well documented and is coded with transmissible genes. Therefore, it is recognized as a model for the monitoring of antibiotic resistance ecology. Homolj, Zlatar and Sjenica cheese have protected geographical indication on the national level. As Homolj, Zlatar and Sjenica cheese are raw milk cheeses produced in the traditional manner, LAB originating from the raw milk and the environment constitute an important part of Serbian traditional cheeses’ microbiota. There are many data in the scientific literature that LAB can carry transmissible antibiotic resistance genes. The aims of this doctoral dissertation were to: characterize biodiversity of traditional Serbian cheeses; determine phenotype and prevalence of antibiotic resistance; define genetic basis of tetracycline resistance in the LAB isolates and to investigate possibility for in vitro transmission of the tet genes. Total of 48 samples traditional Serbian cheeses (13 samples of Homolj cheese, 20 samples of Zlatar cheese and 15 samples of Sjenica cheese) were analyzed. All samples were plated on MRS-S agar plates in order to determine LAB count and on MRS-S agar plates with added tetracycline in doubling concentrations (1-256 μg/ml), in order to determine tetracycline resistant LAB subpopulation count. Average count of LAB in Homolj cheese was 7,65±1,09 log CFU/g, in Zlatar cheese 7,74±0,6 log CFU/g and in Sjenica cheese 7,47±0,71 log CFU/g. Addition of tetracycline in concentration of 64 μg/ml has considerably reduced LAB count, which was in Homolj cheese 3,98±2,28 log CFU/g, in Zlatar cheese 3,35±2,02 log CFU/g and in Sjenica cheese 3,93±2,24 log CFU/g...Lanac hrane predstavlja jedan od mogućih puteva transmisije bakterija rezistentnih na antibiotike između populacija životinja i ljudi. Komensalne bakterije, poreklom od životinja, predstavljaju deo mikrobiote hrane životinjskog porekla, i često se prepoznaju kao „rezervoari“ gena za rezistenciju na antibiotike. Rezistencija na tetraciklin kod komensalnih bakterija je dobro dokumentovana i s obzirom da je prenosive prirode, koristi se kao model za praćenje ekologije rezistencije na antibiotike. Homoljski, zlatarski i sjenički sir su na nacionalnom nivou zaštićeni oznakom geografskog porekla. Proizvode se na tradicionalan način, od sirovog mleka, te bakterije mlečne kiseline, poreklom iz sirovine i/ili procesnog okruženja čine značajan deo mikrobiote tradicionalnih sireva Srbije. U naučnoj literaturi postoje brojni podaci o tome da bakterije mlečne kiseline mogu biti nosioci gena za rezistenciju na antibiotike. Ciljevi ove doktorske disertacije bili su: karakterizacija biodiverziteta tradicionalnih sireva Srbije, utvrđivanje fenotipa i prevalencije rezistencije na antibiotike i genetske baze rezistencije na tetraciklin kod izolata bakterija mlečne kiseline poreklom iz tradicionalnih sireva, kao i mogućnosti prenosa tet gena u uslovima in vitro. Ukupno 48 uzoraka tradicionalnih sireva (13 uzoraka homoljskog sira, 20 zlatarskog i 15 uzoraka sjeničkog sira), zasejano je na MRS-S agar radi utvrđivanja broja BMK i na MRS-S agar sa dodatkom tetraciklina u dvostrukorastućim koncentracijama (1-256 μg/ml), kako bi se utvrdila zastupljenost populacije BMK rezistentne na tetraciklin. Prosečan broj BMK u uzorcima homoljskog sira iznosio je 7,65±1,09 log CFU/g, u uzorcima zlatarskog sira 7,74±0,6 log CFU/g i u uzorcima sjeničkog sira 7,47±0,71 log CFU/g. Pri koncentraciji tetraciklina od 64 μg/ml primećeno je veće smanjenje broja BMK..

Tetracycline resistance in lactic acid bacteria isolated from traditional serbian cheeses

Lanac hrane predstavlja jedan od mogućih puteva transmisije bakterija rezistentnih na antibiotike između populacija životinja i ljudi. Komensalne bakterije, poreklom od životinja, predstavljaju deo mikrobiote hrane životinjskog porekla, i često se prepoznaju kao „rezervoari“ gena za rezistenciju na antibiotike. Rezistencija na tetraciklin kod komensalnih bakterija je dobro dokumentovana i s obzirom da je prenosive prirode, koristi se kao model za praćenje ekologije rezistencije na antibiotike. Homoljski, zlatarski i sjenički sir su na nacionalnom nivou zaštićeni oznakom geografskog porekla. Proizvode se na tradicionalan način, od sirovog mleka, te bakterije mlečne kiseline, poreklom iz sirovine i/ili procesnog okruženja čine značajan deo mikrobiote tradicionalnih sireva Srbije. U naučnoj literaturi postoje brojni podaci o tome da bakterije mlečne kiseline mogu biti nosioci gena za rezistenciju na antibiotike. Ciljevi ove doktorske disertacije bili su: karakterizacija biodiverziteta tradicionalnih sireva Srbije, utvrđivanje fenotipa i prevalencije rezistencije na antibiotike i genetske baze rezistencije na tetraciklin kod izolata bakterija mlečne kiseline poreklom iz tradicionalnih sireva, kao i mogućnosti prenosa tet gena u uslovima in vitro. Ukupno 48 uzoraka tradicionalnih sireva (13 uzoraka homoljskog sira, 20 zlatarskog i 15 uzoraka sjeničkog sira), zasejano je na MRS-S agar radi utvrđivanja broja BMK i na MRS-S agar sa dodatkom tetraciklina u dvostrukorastućim koncentracijama (1-256 μg/ml), kako bi se utvrdila zastupljenost populacije BMK rezistentne na tetraciklin. Prosečan broj BMK u uzorcima homoljskog sira iznosio je 7,65±1,09 log CFU/g, u uzorcima zlatarskog sira 7,74±0,6 log CFU/g i u uzorcima sjeničkog sira 7,47±0,71 log CFU/g. Pri koncentraciji tetraciklina od 64 μg/ml primećeno je veće smanjenje broja BMK...Food chain may represent a possible route for the transmission of antibiotic resistant bacteria between human and animal populations. Commensal bacteria originating from food-producing animals can contaminate food and by that means become a part of the complex food microbiota. Commensal bacteria can also serve as reservoirs for the antibiotic resistance genes. Tetracycline resistance in commensal bacteria is well documented and is coded with transmissible genes. Therefore, it is recognized as a model for the monitoring of antibiotic resistance ecology. Homolj, Zlatar and Sjenica cheese have protected geographical indication on the national level. As Homolj, Zlatar and Sjenica cheese are raw milk cheeses produced in the traditional manner, LAB originating from the raw milk and the environment constitute an important part of Serbian traditional cheeses’ microbiota. There are many data in the scientific literature that LAB can carry transmissible antibiotic resistance genes. The aims of this doctoral dissertation were to: characterize biodiversity of traditional Serbian cheeses; determine phenotype and prevalence of antibiotic resistance; define genetic basis of tetracycline resistance in the LAB isolates and to investigate possibility for in vitro transmission of the tet genes. Total of 48 samples traditional Serbian cheeses (13 samples of Homolj cheese, 20 samples of Zlatar cheese and 15 samples of Sjenica cheese) were analyzed. All samples were plated on MRS-S agar plates in order to determine LAB count and on MRS-S agar plates with added tetracycline in doubling concentrations (1-256 μg/ml), in order to determine tetracycline resistant LAB subpopulation count. Average count of LAB in Homolj cheese was 7,65±1,09 log CFU/g, in Zlatar cheese 7,74±0,6 log CFU/g and in Sjenica cheese 7,47±0,71 log CFU/g. Addition of tetracycline in concentration of 64 μg/ml has considerably reduced LAB count, which was in Homolj cheese 3,98±2,28 log CFU/g, in Zlatar cheese 3,35±2,02 log CFU/g and in Sjenica cheese 3,93±2,24 log CFU/g..

Safety evaluation of Sjenica cheese with regard to coagulase-positive staphylococci and antibiotic resistance of lactic acid bacteria and staphylococci

Sjenica cheese is an artisanal cheese stored in brine, traditionally produced from raw sheeps milk in the southern part of Serbia - Sjenica Pester plateau. The aim of this study was to perform the safety evaluation of Sjenica cheese. As one of the safety criteria we considered the number of coagulase positive staphylococci and their enterotoxigenic potential. Antibiotic susceptibility/resistance patterns of autochthonous lactic acid bacteria and coagulase-positive staphylococci isolated from Sjenica cheese was also investigated. During the monitoring period of the cheese-making process, coagulase positive staphylococci did not reach the value of 10(5) cfu/g. Among coagulase positive staphylococci, 12 (46,15%) isolates showed enterotoxigenic potential and were identified as Staphylococcus intermedius (11 isolates) and Staphylococcus aureus (1 isolate). Vancomycin resistance was the most prevalent phenotypic resistance profile in coagulase positive staphylococci. Lactococci present the most dominant population among lactic acid bacteria. The most prevalent resistance phenotype in lactococci was resistance to streptomycin (83.33%), ampicillin and penicillin (70.83%); lactobacilli were characterized by resistance to vancomycin (62.5%) and tetracycline (54.17%), while resistance to streptomycin (82.46%) was the most prevalent phenotypic profile in enterococci. All coagulase positive staphylococci and lactic acid bacteria isolates that showed resistance to tetracycline on disc diffusion and E-test, were tested for the presence of ribosomal protection proteins, tet(M) and tet(K) genes. All isolates were positive for ribosomal protection proteins genes; 14 (60.87%) isolates showed tet(M) gene presence, while 2 lactobacilli isolates revealed the presence of tet(K) gene

Methods for the antibiotic resistance detection in microorganisms isolated from food

Rezistencija na antibiotike predstavlja rastući problem koji je Svetska zdravstvena organizacija proglasila jednom od najvećih pretnji za globalno zdravlje ljudi. Lanac hrane jedan je od najvažnijih puteva prenošenja i širenja rezistencije na antibiotike između populacije rezistentnih i populacije osetljivih komensalnih i/ili patogenih mikroorganizama. Rezistencija na antibiotike može biti urođena, ili stečena putem mutacija ili lateralnog transfera gena. Sa aspekta širenja rezistencije značajna je samo rezistencija stečena lateralnim transferom gena. Postoje brojne metode za detekciju i određivanje prirode rezistencije na antibiotike kod bakterija izolovanih iz hrane. Neophodno je da metode budu standardizovane i da obezbeđuju konzistentnost i doslednost dobijenih rezultata. Za detekciju fenotipske rezistencije kod bakterija izolovanih iz hrane koriste se metode kojima se određuje minimalna inhibitorna koncentracija antibiotika. U njih spadaju metod mikrodilucije, metod dilucije u agaru i E-testovi. Kvalitativne i semikvantitativne metode koje se često koriste kod kliničkih izolata, nisu prigodne za ispitivanje rezistencije na antibiotike kod mikroorganizama izolovanih iz hrane. Kod mikroorganizama kod kojih se utvrdi prisustvo fenotipske rezistencije na antibiotike, određuje se prisustvo gena za rezistenciju. Mikroorganizmi kod kojih se dokaže prisustvo genetskih determinanti koje su povezane sa stečenom rezistencijom na antibiotike, predstavljaju rizik za diseminaciju rezistencije i među osetljivom populacijom. Mikroorganizmi koji imaju komercijalnu upotrebu, ne bi trebalo da poseduju genetske determinante prenosive rezistencije na antibiotike.Resistance to antibiotics is a growing problem that the World Health Organization has declared one of the biggest threats to global health. The food chain is one of the most important ways of transmitting and spreading resistance to antibiotics between the population of resistant and populated by sensitive commensal and / or pathogenic microorganisms. Resistance to antibiotics can be inborn, or acquired by mutation or lateral gene transfer. From the aspect of the spread of resistance, only resistance acquired by the lateral transfer of the gene is significant. There are numerous methods for detecting and determining the nature of antibiotic resistance in bacteria isolated from food. The methods must be standardized and ensure the consistency of the obtained results. Methods for determining the minimum inhibitory concentration of antibiotics are used to detect phenotypic resistance in bacteria isolated from food. They include a microdilution method, an agar dilution method, and an E-test. Qualitative and semi-quantitative methods commonly used in clinical isolates are not suitable for antibiotic resistance testing in food-isolated microorganisms. In the case of microorganisms with detected presence of phenotypic resistance to antibiotics, the presence of the resistance gene is determined. Microorganisms evidenced by the presence of genetic determinants associated with acquired resistance to antibiotics represent a risk of resistance dissemination among the susceptible populations. Commercially used microorganisms should not possess genetic determinants of transferable antibiotic resistance

Ecology of Listeria monocytogenes

Food safety criteria for Listeria monocytogenes in the ready-to-eat food category have been applied since 2006. In the territory of the European Union in 2019, there were 2 621 confirmed cases of invasive listeriosis in humans, with a high mortality rate (17.6%). A broader understanding of the ecology of Listeria monocytogenes is crucial for the successful control of this pathogen in the food chain continuum. The paper presents new knowledge on reservoirs/sources of contamination, distribution, dynamics and transmission routes, survival and persistence of Listeria monocytogenes, both in natural habitat and in farm or processing environment

Jedno zdravlje – izazov i prilika za veterinare

U današnje vreme, više nego ikad, naglašava se međuzavisnost ljudi, životinja i njihovog okruženja. Na osnovu onoga što veterinar- ska profesija jeste u svojoj osnovi, „Jedno zdravlje“ nudi veterinarima jedinstvenu priliku da zauzmu ključnu ulogu u ovom specifičnom pri- stupu sagledavanja sveukupnosti zdravlja. Pitanje koje se neminovno postavlja je – da li su i u kojoj meri veterinari spremni da odgovore na postavljeni izazov

Spore-forming bacteria in the dairy chain

Spore-forming bacteria form the most diverse and most complex group of bacteria in terms of their elimination from the dairy chain, due to their ability to form highly resistant spores. As ubiquitous microorganisms, spore-formers can enter the product along the milk-processing continuum from different sources, and subsequently cause spoilage in various types of dairy products. The most important classes of spore-forming bacteria relevant to the dairy industry are Bacilli and Clostridia. Bacilli are responsible mainly for the spoilage and decreased shelf-life of fluid milk, while Clostridia cause late gas blowing in cheese. Spore-forming microorganisms contaminate raw milk primarily at the farm level, with potential for recontamination to occur at various points along the dairy production continuum. The most effective measure in reducing spore load at the farm level is adequate pre-milking teat preparation, while at the dairy plant level, bactofugation and microfiltration are applied. Understanding the ecology of spore-formers can improve application of systematic approaches for controlling the spoilage bacteria in dairy processing systems. Also, novel technologies, such as high-pressure processing, ultrasound treatment, irradiation etc., could provide the dairy industry with the powerful tools to eliminate these bacteria from the dairy chain

METHODS FOR THE ANTIBIOTIC RESISTANCE DETECTION IN MICROORGANSIMS ISOLATED FROM FOOD

Resistance to antibiotics is a growing problem that the World HealthOrganization has declared one of the biggest threats to global health. The foodchain is one of the most important ways of transmitting and spreading resistanceto antibiotics between the population of resistant and populated by sensitivecommensal and / or pathogenic microorganisms. Resistance to antibiotics can beinborn, or acquired by mutation or lateral gene transfer. From the aspect of thespread of resistance, only resistance acquired by the lateral transfer of the geneis significant. There are numerous methods for detecting and determining thenature of antibiotic resistance in bacteria isolated from food. The methods mustbe standardized and ensure the consistency of the obtained results. Methods fordetermining the minimum inhibitory concentration of antibiotics are used to detectphenotypic resistance in bacteria isolated from food. They include a microdilutionmethod, an agar dilution method, and an E-test. Qualitative and semi-quantitativemethods commonly used in clinical isolates are not suitable for antibiotic resistancetesting in food-isolated microorganisms. In the case of microorganisms withdetected presence of phenotypic resistance to antibiotics, the presence of theresistance gene is determined. Microorganisms evidenced by the presence of geneticdeterminants associated with acquired resistance to antibiotics represent a risk ofresistance dissemination among the susceptible populations. Commercially usedmicroorganisms should not possess genetic determinants of transferable antibioticresistance

Milk: Past and Present

Although milk/dairy consumption is part of many cultures and is recommended in most dietary guidelines around the world, its contribution to overall diet quality remains a matter of controversy, leading to a highly polarized debate within the scientific community, media and public sector. The present article, at first, describes the evolutionary roots of milk consumption, then reviews the milk-derived bioactive peptides as health-promoting components. The third part of the article, in general, presents the associations between milk nutrients, disease prevention, and health promotion

Production and trade of milk and dairy products in Serbia

Milk plays a significant role in human nutrition, and more than 6 billion people worldwide con‑ sume milk and dairy products. In 2019, total milk production in Serbia reached 1,597 million litres, cow’s milk accounting for almost 95%. Out of the total amount of cow’s milk produced in 2021, 58.2% was purchased. The share of milk delivered to dairies increased by over 50% in the previous decade. The results in the dairy sector are directly influenced by dairy cattle farming in Serbia, which has been experiencing a decrease, but there has been a consistent increase in milk yield over the past few years. Production of dairy products in Serbia recorded a decrease during the last ten years, except for dry products (cream powder, whole and partially‑skimmed milk powder), which recorded an increase. Trade in dairy products is very volatile, as dairy trade flows can be affected by the overall economic situation in a country, fluctuations in supply and demand, changing exchange rates and political measures. The largest dairy product trade in Serbia is conducted in milk and cream, followed by cheese, and then milk and cream powder