Antimikrobna osetljivost bakterija mlečne kiseline izolovanih iz Somborskog sira

Extensive literature data pointed out that some lactic acid bacteria (LABs), the predominant microbiota in fermented dairy products, may serve as reservoirs of antibiotic resistance genes potentially transferable to human pathogens. Hence, there is a growing interest in the possible role of LAB as vectors of antibiotic resistance determinants. This paper reports the susceptibility patterns of a number of LAB species (belonging to the genera Lactococcus, Lactobacillus, and Enterococcus) isolated from different batches of autochthonous Sombor cheese, traditionally made without the addition of starter cultures, and currently proposed as a candidate for PDO/PGI designation. The experimental work was performed to select strains that do not contain antibiotic resistance genes among those with desirable technological characteristics such as rapid acidification, proteolysis, ability to metabolise citrate and form aromogenic compounds. In addition, the results of these screening procedures could also indicate the types and degrees of antimicrobial resistance already present among the LAB community of Sombor cheese, which according to their geographically restricted areas of production, specific manufacturing process and characteristic aroma and appearance, represent a distinct ecological niche.Opsežni literaturni podaci ukazuju da pojedine bakterije mlečne kiseline, čineći dominantnu mikrofloru u fermentisanim proizvodima od mleka, mogu poslužiti kao rezervoar gena rezistencije na antibiotike, potencijalno prenosivih na patogene mikroorganizme. Stoga postoji rastući interes o mogućoj ulozi bakterija mlečne kiseline kao vektora determinanti rezistencije. Ovaj rad izveštava o profilima antibiotske osetljivosti vrsta bakterija mlečne kiseline (rodovi Lactococcus, Lactobacillus i Enterococcus) izolovanih iz različitih linija proizvodnje autohtonog Somborskog sira, tradicionalno proizvedenog bez dodatka starter kulture, a predloženog za dobijanje oznake geografskog porekla. Eksperimentalni rad je izveden u cilju selekcije sojeva koji ne sadrže gene rezistencije na antibiotike, ali su ujedno nosioci poželjnih tehnoloških karakteristika kao što su brza acidifikacija, proteoliza, sposobnost metabolisanja citrata i formiranje aromogenih komponenti. Ujedno, rezultati ovih 'screening' procedura mogu ukazati na tip i stepen antimikrobne rezistencije prisutne među zajednicom bakterija mlečne kiseline Somborskog sira, koji prema geografski određenom području proizvodnje, specifičnom procesu proizvodnje i karakterističnoj aromi i izgledu predstavlja zasebnu ekološku nišu

Antibiotic Susceptibility of Probiotic Bacteria

Lactic acid bacteria (LAB) are a heterogeneous group of bacteria widely distributed in nature. These bacteria are found in gastrointestinal (GI) and urogenital tract of humans and animals; they are present on plant material, in milk and meat, and numerous fermented foods. Lactic acid bacteria have been associated with traditional dairy products, cereals, vegetable and meat fermented foods, due to their natural presence leading to spontaneous fermentation. They are also used as starter cultures in industrial food production, as well as in the production of probiotic products due to their potential health benefits to consumer. Milk and dairy products are the most examined food system for the delivery of probiotic bacteria to the human gut. The probiotic concept has progressed and is now in the focus of different research. Significant improvements have been made in selection and characterization of new cultures and their application in food production. The food products, which are produced by traditional methods, exhibit a rich biodiversity with the respect to bacterial contents. From these products, new probiotic strains with the potential functional properties can been isolated and selected. The selected strains have to be further characterized in order to be used in the food industry. Before the probiotics can benefit human health, they must fulfill several criteria including: a) scientifically validated health properties; b) good technological properties meaning that they can be manufactured and incorporated into food products without loosing viability, functionality and technological performance; c) high survival through the upper gastrointestinal tract and high viability at its site of action; d) antagonistic activity to pathogens; e) antibiotic susceptibility; and f) to be able to function in the gut environment. Bearing in mind importance of antibiotic resistance of LAB in food chain, antibiotic susceptibility of potential probiotic strains is a very important criteria for their selection. In the recent decade, releasing of antibiotics in biosphere seriously increased, leading to a strong selective pressure for the emergence and persistence of resistant LAB strains. Since LAB are naturally present in traditionally made fermented food and GI tract and are also added as starter culture or probiotic bacteria in industrial food production, concerns have been raised about the antibiotic resistance of these beneficial bacteria strains. Probiotic bacteria can help maintaining balance in gastrointestinal tract in cases of diarrhea caused by antibiotic treatment. However, there is high risk associated with the ability of these resistant strains to transmit the resistance gene to pathogenic bacteria in gut microbiota. This can complicate the treatment of a patient with an antibiotic resistant bacterial infection or disease. The circulation of genes coding for antibiotic resistance from beneficial LAB in the food chain via animals to humans is a complex problem. Therefore, there is a need to evaluate the safety of potential probitic strains regarding their ability to acquire and disseminate antibiotic resistance determinants in selection of LAB. In this study, importance of LAB in the food chain will be reviewed. Morphological and biochemical characteristics of lactobacilli, bifidobactera and enterococci, as well as criteria for probiotic selection and role of probiotics in health benefit will be discussed. Antibiotic susceptibility as criteria for potential probiotic bacteria selection and mechanisms of gene transfers will be considered

Procena mikrobiološkog rizika kod sireva proizvedenih od sirovog mleka

Microbiological risk assessment of raw milk cheeses must be performed in the framework of complex interplay between several intrinsic and extrinsic parameters which dictate the potential for bacterial pathogens to grow, persist and/or decline in cheeses. In this paper, we discuss the main components of microbiological risk assessment including the incidence and prevalence of food borne pathogens in raw milk cheeses, effect of manufacturing steps during cheese making, physicochemical characteristics of individual cheese matrix (pH, salt content, and water activity) and the growth requirement of specific food borne pathogen.Procenu mikrobiološkog rizika kod sireva proizvedenih iz sirovog mleka potrebno je sagledati kroz okvir složenog međudelovanja nekoliko intrinzičnih i ekstrinzičnih parametara koji diktiraju potencijal rasta, preživljavanja i/ili inhibicije patogenih mikroorganizama. U ovom radu predstavljamo glavne komponente procene mikrobiološkog rizika, pre svega, nalaz i zastupljenost patogenih mikroorganizama u sirevima proizvedenim od sirovog mleka, efekat pojedinih faza proizvodnje, fizikohemijske karakteristike specifične za matriks pojedinih sireva (pH, sadržaj soli, aktivnost vode), kao i zahteve rasta specifičnih uzročnika alimentarnih oboljenja

Sirovo mleko kao izvor Bacillus vrsta odgovornih za kvar proizvoda od mleka

Bacillus spp. are often present as contaminants in raw milk. Due to thermo resistance of their spores, bacilli survive after the heat treatment in milk industry. The proteolytic activity of bacilli leads to spoilage of milk and milk products and according to that influenced the durability of milk product. The material of investigation consisted of 243 samples of raw milk, 40 samples of pasteurized milk and corresponding 40 samples of raw milk during the milk pasteurization and 60 samples of pasteurized milk on expiry date. The proteolytic activity of bacilli was determined according to modified method that is established by Hill and Gasson (1986). The level of Bacillus spp. contamination of raw milk was 2,76±0,72 log10 cfu/ml, 1,74±2,52 log10 cfu/ml for pasteurized during production process, and level of Bacillus spp. contamination of final product-pasteurized milk was 2,38±0,47 log10 cfu/ml. It was determined the presence of following species: B. licheniformis 46,15%, B. pumilus 15,38%, B. subtilis 15,38%, B. brevis 11,54%, B. sphaericus 7,69%, B. cereus 3,85% in raw milk and B. subtillis 71,42%. B. pumilus 14,28% i B. licheniformis 14,28% in pasteurized milk during the production process. Isolated strains of Bacillus spp. showed significant proteolytic activity which have influenced the durability of pasteurized milk.Bacillus spp. su često prisutni kontaminenti sirovog mleka. S obzirom na termorezistent njihovih spora opstaju pri termičkim tretmanima u mlekarskoj industriji. Njihova proteolitička aktivnost dovodi do kvara mleka i time utiče na smanjenu održivost proizvoda od mleka. U radu smo ispitali zastupljenost bacila u sirovom mleku, uticaj temperatura pasterizacije na redukciju bacila u termički obrađenom mleku, kao i proteolitičku aktivnost izolovanih sojeva. Materijal su predstavljala 243 uzorka sirovog mleka, 40 uzoraka pasterizovanog i paralelnih 40 uzoraka sirovog mleka tokom procesa pasterizacije i 60 uzoraka pasterizovanog mleka na kraju perioda održivosti. Proteolitička aktivnost Bacillus spp. određivana je na kazeinskom agaru kao "screening" metoda, a analiza proteolitičke aktivnosti celih ćelija Bacillus spp. u odnosu na proteinske supstrate je vršena modifikovanom metodom koju su razvili Hill i Gasson (1986). Nivo kontaminacije sirovog mleka sa Bacillus spp. je iznosi 2,76±0,72 log10 cfu/ml, pasterizovanog mleka tokom procesa proizvodnje 1,74±2,52 log10 cfu/ml, dok je nivo kontaminacije upakovanog pasterizovanog mleka sa Bacillus spp. iznosio 2,38±0,47 log10 cfu/ml. Identifikacijom sojeva Bacillus spp. izolovanih iz sirovog mleka ustanovljeno je prisustvo: B. licheniformis sa 46,15%, B. pumilus sa 15,38%, B. subtilis sa 15,38%, B. brevis sa 11,54%, B. sphaericus sa 7,69 i B. cereus sa 3,85%, a u pasterizovanom mleku tokom procesa proizvodnje ustanovljeno je prisustvo B. subtillis 71,42%. B. pumilus 14,28% i B. licheniformis 14,28%. Izolovani sojevi Bacilus spp. pokazali su izrazitu proteolitičku aktivnost što za posledicu ima smanjenje održivosti i kvar pasterizovanog mleka

Rizik prisustva stafilokoka u sirevima

Coagulase positive staphylococci isolated from autochthonous cheeses were screened regarding their enterotoxigenic potential and antimicrobial resistance profile. By applying the VIDAS techology, out of 73 coagulase positive staphylococcal isolates, 22 (30,14%) strains showed enterotoxigenic potential. The 50% analysed strains showed antimicrobial resistance properties at least at one of antibiotics tested, and among those resistant population 54,54% strains were characterized by multiple resistance. The obtained results presented the strong argument in risk characterization.Koagulaza pozitivni sojevi izolovani iz autohtonih sireva su okarakterisani u odnosu na njihov enterotoksogeni potencijal i profil fenotipske antimikrobne rezistencije. Primenom VIDAS tehnologije, od 73 koagulaza pozitivna soja stafilokoka analiziranih u našem radu, potencijal produkcije enterotoksina je pokazalo 22 (30,14%) sojeva. Rezistencija na jedan ili više odabranih antibiotika je utvrđena kod 11 (50%) sojeva, od kojih se 6 (54,54%) karakterisalo svojstvom multiple rezistencije. Svojstvo enterotoksogenosti i antimikrobne rezistencije ispitivanih koagulaza pozitivnih stafilokoka predstavlja snažan argument u karakterizaciji rizika njihovog prisustva u sirevima

Koncept zaštite imena namirnica životinjskog porekla

The currently valid regulations (Official Gazette 26/2002) define the requirements for the quality of milk and milk products. The same legislature defines also the concept of composite products, that is, products in which part of the fat or proteins have been substituted with fat or proteins of different origin. A composite product must include the term composite in its name, and the part of the declaration which lists the contents of total proteins and fat must specify the part of plant proteins and fat in total proteins and fat of milk products. With the growth of the population and the concern for health, new requirements have been set, and consumers expect a food article to meet not only the nutritive requirements, but also to have certain functional characteristics, or that it is not burdened with components which have a negative effect on health (the presence of cholesterol, sodium chloride, a high percentage of saturated fatty acids). The complete substitution of one milk component results in a completely new product. A change in the traditional composition of a certain food article must be clearly declared, so as not to confuse consumers and to provide them with the possibility of choice. In our market, there have lately appeared products that are marked as imitations, alternatives, diet cheese, vegetable cheese. Modified products which do not meet the traditional identity standards must be marked as imitations, in case they are nutritionally inferior with respect to the traditionally standardized food articles, or as substitutes or alternatives, in the event that they are a nutritive equivalent to the traditional food articles. The lack of legal regulations for this category of product leads to the irregular declaration of such products, and consequently provides false information about the characteristics of such articles to the consumer. It is necessary to regulate this area with the respective laws in order to protect the consumer.Prema važećem propisu [1] definisani su zahtevi kvaliteta za mleko i proizvode od mleka. U istom pravilniku definisan je i pojam kompozitnih proizvoda, tj. proizvoda kod kojih je deo masti ili belančevina zamenjen mastima i belančevinama drugog porekla. Kompozitni proizvod u naslovu mora da ima oznaku kompozitni i u delu deklaracije koja govori o sastojcima, označene ukupne proteine i masti i udeo biljnih proteina i masti u ukupnim proteinima i mastima proizvoda od mleka. Porastom populacije i brigom za zdravlje postavljeni su novi zahtevi, a potrošači očekuju da namirnica ne zadovoljava samo nutritivne potrebe, nego da poseduje i određene funkcionalne karakteristike ili da nije opterećena komponentama koje negativno utiču na zdravlje (prisustvo holesterola, natrijum-hlorida i visok procenat zasićenih masnih kiselina). Potpunom zamenom jedne komponente mleka dobija se nov proizvod. Promena tradicionalnog sastava namirnice mora da bude i jasno deklarisana kako proizvođača ne bi dovela u zabludu, a ostavila mu mogućnost izbora i samoopredeljenja. Na našem tržištu se u poslednje vreme pojavljuju proizvodi koji nose oznaku imitacija, alternativa, posni sir i biljni sir. Modifikovani proizvodi koji ne zadovoljavaju tradicionalne standarde identiteta moraju da se označe kao imitacije, u slučaju da su nutritivno inferiorni u odnosu na tradicionalnu standardizovanu namirnicu, odnosno kao supstitucije ili alternative, u slučaju da su nutritivno ekvivalentni tradicionalnoj namirnici. Nepostojeća pravna regulativa za ovu kategoriju proizvoda dovodi do nepravilnog deklarisanja takvih proizvoda i time neminovno daje pogrešnu informaciju potrošaču o karakteristikama takve namirnice. Radi zaštite potrošača neophodno je da se zakonski reguliše ova oblast

Nalaz i aktivnost bakterija mlečne kiseline u autohtonom sjeničkom siru

In this article the prevalence of lactic acid bacteria through the production and ripening period of autochthonous Sjenica cheese was reviewed. The activity of main LAB group was evaluated by pH changes and evolution of ripening coefficient.U radu je prikazana prevalenca bakterija mlečne kiseline tokom procesa proizvodnje i zrenja autohtonog sjeničkog sira. Aktivnost bakterija mlečne kiseline je procenjena na osnovu promene pH vrednosti i koeficijenta zrelosti tokom perioda zrenja od 90 dana

Fiziološke karakteristike psihrotrofnih bacila izolovanih iz sirovog mleka

The strains of genus Bacillus are often present as containments in raw milk. Their ubiquitous nature, potentiality to produce thermorcsistent spores, ability to grow and bio­chemical activity at low temperatures, so as pathogenicity of some strains have actualized their significance in food industry. The isolation of psychrotrophic bacilli was conducted after incubation of 10 days at 7±1°C (isolation is achieved only from milk samples which demonstrate the changes of Bacillus number at the start and after 10 days of incubation at 7±1°C). It was examined 56 psychrotrophic strains of bacilli isolated from raw milk. During incu­bation of 10 days at 7±1°C, in 50 samples of raw milk the number of bacilli increased from log 0.8±0.78 to 1.73±0.86, whereas in 6 samples the Bacillus number ranged from log 0.10±0.01 to 2.07±0.47. The differences between mean values of Bacillus number on the first and tenth days of incubation at low temperatures (psychrotrophic condition) were subjected to the t-test. It was noticed a highly significant difference. It was also found that 30.35% of isolated strains were heamolytic, 64.28% degraded lechitin, 5.35% broke down gelatin, 78.57%; de­graded casein. A high percentage of isolated bacilli (97.07%) grew at pH 5.7 and 78.57% multiplied in the presence of 7% NaCl.Predstavnici roda Bacillus često su prisutni kao kontaminenti u sirovom mleku. Njihova ubikvitarnost, stvaranje tennorezistentnih spora, sposobnost rasta i biohemijska aktivnost pri niskim temperaturama kao i patogenost pojedinih sojeva aktueliziraju njihov značaj u industriji hrane. Izolacija psihrotrofnih bacila je izvedena posle inkubacije sirovog mleka ud 10 dana na 7±1°C. Psihrotrofni bacili su izolovani samo iz uzoraka koji su pokazivali promenu broja bacila na početku inkubacije I posle 10 dana inkubacije na 7±1°C. Testirana su 56 psihrolrofna soja bacila izolovana iz sirovog mleka. Broj bacila se tokom inkubacije od 10 dana na 7±1°C u 50 uzoraka sirovog mleka povećao sa log0.81±0.78na 1.73±0.86, au6uzorakasa log 0.10±0.10na 2.07±0.47. Statistički je utvrđeno da je promenu broja bacila u uslovima niskih temperatura za period od 10 dana visoko značajna. Izolovani psihrotrofni bacili su u 30,35% hemolitični, 64,28% ledtinaza pozitivni, 5,35% sojeva razlaže želatin, a 78,57% sojeva razlazu kazein. Sposobnost rasta u medijumu sa pH 5,7 pokazuje 97.07% sojeva, a 78,57% raste u prisustvu 7% NaCl

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

New insight into foodborne diseases

Široki spektar alimentarnih infekcija se, tokom vremena, značajno menja, kako se dobro okarakterisani patogeni stavljaju pod kontrolu ili u potpunosti eliminišu, a novi prepoznaju. Novi patogeni se identifikuju kao rezultat bilo promenjene ekologije ili promena u tehnologiji koje povezuju potencijalni patogen sa lancem hrane, ali i transferom mobilnih faktora virulencije, vrlo često putem bakteriofaga. "Novi" patogeni se regrutuju bilo iz konzorcijuma uzročnika tzv. "tihih" zoonoza ili onih koji su odgovorni za ozbiljne infekcije kod imunokompromitovanih osoba. Slikovito rečeno, možemo očekivati neočekivano. Mnogi faktori predstavljaju pokretačku silu odgovornu za ispoljavanje alimentarnih oboljenja, pre svega, promene u demografiji, ponašanju i navikama ljudi, industriji hrane i tehnologiji, trend globalne ekonomije i centralizovane proizvodnje i prerade hrane, ali i univerzalna sposobnost adaptacije mikroorganizama.The broad spectrum of foodborne infections has changed dramatically over time, as well-established pathogens have been controled or eliminated, and the new ones have emerged. New pathogens can emerge because of changing ecology or changing technology that connects a potential pathogen with the food chain., but also by transfer of mobile virulence factors, often through bacteriophage. One may look for emerging pathogens among silent zoonoses, and among the severe infections affecting the immunocompromised humans. Literally, we should expect the unexpected. Emergence in foodborne infections is driven by multiple factors: changes in demographic characteristics, human behavior, industry and technology, shift to global economy and centralized food proccessing and microbial adaptation