Changes in population of S. enterica serotype Enteritidis in experimentally contaminated milk depending on temperature and acidity

Salmonella bacteria are among the most frequent causes of food poisoning, and milk and milk products are food items through which these bacteria can be transmitted. More recent data indicate that the infective dose of Salmonella is very small - up to 101/g/ml food. The preservation of Salmonella in milk depends on the acidity, temperature and the duration of storage. The objective of the work was to examine the survival of Salmonella in milk depending on the changes of the total number of bacteria, pH and temperature. In the study, 0.1 ml of 24-hour bouillon culture of S. enteritidis was inoculated in raw collective milk (104 cfu/ml) and in marketed pasteurized milk (102 cfu/ml) each. The examined milk samples were maintained at room temperature and at a temperature of 7oC. At the beginning of the examinations, after 24h, 48h, 72h, after 7, 14 and 21 days, decimal solutions were made from the milk, and, following incubation, the number of S. enteritidis was determined (Rambach agar), the total number of bacteria (base for total number of bacteria) by multiplying the number of grown colonies and the corresponding solution, and the milk pH was measured. There was a bigger reduction of S. enteritidis at room temperature because the pH value dropped more swiftly. The lowest pH at which S. enteritidis was isolated from experimentally contaminated milk was 3.88. The results of the examinations show that Salmonella can adapt to biochemical processes during milk acid fermentation of soft cheeses. No Salmonella bacteria were isolated from experimentally contaminated pasterurized milk at both maintenance temperatures after seven days of investigations

Phenotype and genotype charactristics of coagulase - positive staphylococci isolated from cows udder

Mastitis je najčešće obolenje mlečnih krava i uzrok je najvećih gubitaka u primarnoj proizvodnji mleka u svetu, a najčešće su izazvani koagulaza pozitivnim stafilokokama. Rezistencija stafilokoka izolovanih u slučajevima mastitisa prema antimikrobnim sredstvima je u porastu i prati rezistenciju stafilokoka izolovanih u slučajevima oboljenja ljudi, pre svega na penicilin i ampicilin, kao i na preparate iz drugih grupa antimikrobnih lekova. Najznačajniji toksini koji stvaraju koagulaza pozitivne stafilokoke su enterotoksini i imaju veliki značaj za zdravlje ljudi, jer izazivaju alimetarne intoksikacije, a mleko i proizvodi od mleka predstavljaju rizične proizvode u kojima se enterotksini mogu naći. Novija istraživanja pokazuju da do 93,6% stafilokoka izolovanih u slučajevima mastitisa ima sposobnost da stvara jedan ili više enterotoksina. Cilj istraživanja je bio da se utvrdi da li postoji razlika u fenotipskim i genotipskim karakteristikama koagulaza pozitivnih stafilokoka izolovanih iz uzoraka mleka uzetih u slučajevima latentne infekcije, subkliničkih mastitisa i kliničkih mastitisa krava u različitim fazama laktacije i da li postoji veza izmeĎu osetljivosti koagulaza pozitivnih stafilokoka na antimikrobne lekove i prisustva gena za stvaranje enterotoksina. Uzorci mleka za bakteriološko ispitivanje na uzročnike mastitisa su uzeti iz pojedinih četvrti vimena od 9.181 krave u različitim fazama laktacije sa tri farme. Kod svih (830) izolata koagulaza pozitivnih stafilokoka koji su izolovani iz uzoraka mleka uzetih u različitim fazama laktacije ispitana je osetljivost disk difuzionom metodom po Kirbi Bauer-u na odabrane antimikrobne lekove. Za ispitivanje rezistencije na meticilin oksi testom sa oksicilinom i cefoksitinom ispitano je 373 izolata za koje je disk difuzionim testom utvrĎeno da su rezistentni na penicilin G. Za ispitivanje biohemijskih osobina i sposobnosti sinteze enterotoksina odabrano je 50 izolata koagulaza pozitivnih stafilokoka izolovanih iz uzoraka mleka krava sa subkliničkim mastitisom od kojih je za 35 (78,6%) izolata disk difuzionom metodom utvrĎeno da su rezistentni na penicilin G i 15 (21,4%) izolata osetljivo na penicilin G. diskovi antimikrobnih lekova sledećih koncetracija: penicilin G 6μg (Torlak), amoksicilin/klavulanska kiselina (20+10 μg ) (Oxoid), kloksacilin 25 μg (Oxoid), amoksicilin 30 μg (Torlak), cefaleksin 30 μg (Torlak), ceftiofur 30 μg (Oxoid), linkomicin 15 μg (Oxoid), gentamicin 30 μg (Torlak), i tetraciklin 30 μg (Torlak)...Mastitis in dairy cows is the persistent, inflammatory reaction of udder tissue. Mastitis cause the greater losses on primary production in milk in world, and most prevalence pathogens are coagulase-positive staphylococci. Resistance of staphylococci into the isolated in bovine udder a cases of mastitis on antimicrobial agents increasing and monitoring resistance of isolated staphylococci in cases in humans infections, especially of penicillin and ampicillin, as well as the preparation of other groups of antibiotics. The main toxins produced coagulase positive staphylococci are enterotoxins and have great significance of human health, causing alimntary intoxication. Milk and milk products are risk factors for enterotoxins existing. Recent research shows that up to 93,6% of staphylococci isolated in cases of mastitis in the ability in produces one or more enterotoxins. The aim of this study was to determine whether there are differences in phenotypic and genotypic characteristics of coagulase-positive staphylococci isolated from milk samples taken in cases of latent infection, mastitis, subclinical and clinical mastitis at different stages of lactation, and whether there is a link between susceptibility of coagulase-positive staphylococci antimicrobial drugs and the presence of genes for production of enterotoxins. Milk samples for bacteriological examination of the causes of mastitis are taken from individual quarters of the udder from 9,181 cows at different stages of lactation from three farms. In all (830) isolates of coagulase-positive staphylococci, isolated from milk samples taken at different stages of lactation examined the sensitivity of disk diffusion method by Kirby-Bauer in the selected antimicrobials. To test resistance to methicillin oxy test with oxacillin and cefoxitin were examined 373 isolates for which the disk diffusion assay showed that are resistant to penicillin G. For the investigation of biochemical properties and the ability to synthesize enterotoxin of 50 selected isolates of coagulase-positive staphylococci isolated from milk samples of cows with subclinical mastitis of which is 35 (78.6 %) isolates by disk diffusion method showed that are resistant to penicillin G and 15 (21,4 %) isolates susceptible to penicillin G. Drives the following concentrations of antibiotics: penicillin G 6μg (Torlak), amoxicillin/clavulonic acid (20+10mg) (Oxoid), cloxacillin 25 mg (Oxoid), amoxicillin 30 mg (Torlak), cephalexin 30 mg (Torlak), ceftiofur 30 mg (Oxoid), lincomycine 15 mg (Oxoid), gentamicine 30 mg ( Torlak ) and tetracycline 30 mg (Torlak)..

Phenotype and genotype charactristics of coagulase - positive staphylococci isolated from cows udder

Mastitis je najčešće obolenje mlečnih krava i uzrok je najvećih gubitaka u primarnoj proizvodnji mleka u svetu, a najčešće su izazvani koagulaza pozitivnim stafilokokama. Rezistencija stafilokoka izolovanih u slučajevima mastitisa prema antimikrobnim sredstvima je u porastu i prati rezistenciju stafilokoka izolovanih u slučajevima oboljenja ljudi, pre svega na penicilin i ampicilin, kao i na preparate iz drugih grupa antimikrobnih lekova. Najznačajniji toksini koji stvaraju koagulaza pozitivne stafilokoke su enterotoksini i imaju veliki značaj za zdravlje ljudi, jer izazivaju alimetarne intoksikacije, a mleko i proizvodi od mleka predstavljaju rizične proizvode u kojima se enterotksini mogu naći. Novija istraživanja pokazuju da do 93,6% stafilokoka izolovanih u slučajevima mastitisa ima sposobnost da stvara jedan ili više enterotoksina. Cilj istraživanja je bio da se utvrdi da li postoji razlika u fenotipskim i genotipskim karakteristikama koagulaza pozitivnih stafilokoka izolovanih iz uzoraka mleka uzetih u slučajevima latentne infekcije, subkliničkih mastitisa i kliničkih mastitisa krava u različitim fazama laktacije i da li postoji veza izmeĎu osetljivosti koagulaza pozitivnih stafilokoka na antimikrobne lekove i prisustva gena za stvaranje enterotoksina. Uzorci mleka za bakteriološko ispitivanje na uzročnike mastitisa su uzeti iz pojedinih četvrti vimena od 9.181 krave u različitim fazama laktacije sa tri farme. Kod svih (830) izolata koagulaza pozitivnih stafilokoka koji su izolovani iz uzoraka mleka uzetih u različitim fazama laktacije ispitana je osetljivost disk difuzionom metodom po Kirbi Bauer-u na odabrane antimikrobne lekove. Za ispitivanje rezistencije na meticilin oksi testom sa oksicilinom i cefoksitinom ispitano je 373 izolata za koje je disk difuzionim testom utvrĎeno da su rezistentni na penicilin G. Za ispitivanje biohemijskih osobina i sposobnosti sinteze enterotoksina odabrano je 50 izolata koagulaza pozitivnih stafilokoka izolovanih iz uzoraka mleka krava sa subkliničkim mastitisom od kojih je za 35 (78,6%) izolata disk difuzionom metodom utvrĎeno da su rezistentni na penicilin G i 15 (21,4%) izolata osetljivo na penicilin G. diskovi antimikrobnih lekova sledećih koncetracija: penicilin G 6μg (Torlak), amoksicilin/klavulanska kiselina (20+10 μg ) (Oxoid), kloksacilin 25 μg (Oxoid), amoksicilin 30 μg (Torlak), cefaleksin 30 μg (Torlak), ceftiofur 30 μg (Oxoid), linkomicin 15 μg (Oxoid), gentamicin 30 μg (Torlak), i tetraciklin 30 μg (Torlak)...Mastitis in dairy cows is the persistent, inflammatory reaction of udder tissue. Mastitis cause the greater losses on primary production in milk in world, and most prevalence pathogens are coagulase-positive staphylococci. Resistance of staphylococci into the isolated in bovine udder a cases of mastitis on antimicrobial agents increasing and monitoring resistance of isolated staphylococci in cases in humans infections, especially of penicillin and ampicillin, as well as the preparation of other groups of antibiotics. The main toxins produced coagulase positive staphylococci are enterotoxins and have great significance of human health, causing alimntary intoxication. Milk and milk products are risk factors for enterotoxins existing. Recent research shows that up to 93,6% of staphylococci isolated in cases of mastitis in the ability in produces one or more enterotoxins. The aim of this study was to determine whether there are differences in phenotypic and genotypic characteristics of coagulase-positive staphylococci isolated from milk samples taken in cases of latent infection, mastitis, subclinical and clinical mastitis at different stages of lactation, and whether there is a link between susceptibility of coagulase-positive staphylococci antimicrobial drugs and the presence of genes for production of enterotoxins. Milk samples for bacteriological examination of the causes of mastitis are taken from individual quarters of the udder from 9,181 cows at different stages of lactation from three farms. In all (830) isolates of coagulase-positive staphylococci, isolated from milk samples taken at different stages of lactation examined the sensitivity of disk diffusion method by Kirby-Bauer in the selected antimicrobials. To test resistance to methicillin oxy test with oxacillin and cefoxitin were examined 373 isolates for which the disk diffusion assay showed that are resistant to penicillin G. For the investigation of biochemical properties and the ability to synthesize enterotoxin of 50 selected isolates of coagulase-positive staphylococci isolated from milk samples of cows with subclinical mastitis of which is 35 (78.6 %) isolates by disk diffusion method showed that are resistant to penicillin G and 15 (21,4 %) isolates susceptible to penicillin G. Drives the following concentrations of antibiotics: penicillin G 6μg (Torlak), amoxicillin/clavulonic acid (20+10mg) (Oxoid), cloxacillin 25 mg (Oxoid), amoxicillin 30 mg (Torlak), cephalexin 30 mg (Torlak), ceftiofur 30 mg (Oxoid), lincomycine 15 mg (Oxoid), gentamicine 30 mg ( Torlak ) and tetracycline 30 mg (Torlak)..

Susceptibility of coagulase positive staphylococci isolated from cow's mammary gland to antibacterial drugs

Coagulase positive staphylococci are one of the most common causes of chronic udder infection. Indiscriminate use of antimicrobial drugs and their presence in the environment where animals live has led to coagulase positive staphylococci strains resistant to antimicrobial means. Proper and timely treatment of sub-clinical mastitis, based on the most effective use of antimicrobial drugs, is the key to good health of the milk herd. The aim was to determine the antimicrobial efficacy of selected assets in relation to coagulase positive staphylococci isolated from samples of milk taken from individual udder quarters of cows in cases of udder infection from three farms with different mastitis prevalence. From a total of 9245 samples of milk taken from individual udder quarters of cows from three farms, 852 strains isolated were coagulase positive staphylococci. Coagulase positive staphylococci were isolated on blood agar and identified on the basis of macro-morphological characteristics and the coagulase and catalase test. The sensitivity of the coagulase positive staphylococci was tested by the Kirby Bauer agar diffusion method with the following antimicrobials: penicillin 6µg, amoxicillin / sulbactam (20 +10µg), cloxacillin 25 µg, cefalexin 30 µg, ceftiofur 30µg, linkomycin 15µg, 30 µg gentamycin and tetracycline 30 µg. Sensitivity testing of coagulase positive staphylococci, isolated in cases of intramammary cow infections, established a high degree of sensitivity in vitro towards penicilinasa resistant drugs (amoxicillin-sublactam, cloxacilin), cephalosporins of the first and third generations and linkomycin. The highest levels of resistance to penicillin (70.4%) were found on a farm with a moderate prevalence of udder infection, then on the farm with the highest prevalence of intramammary infections (60.2%) and the lowest on the farm with controlled levels of resistance of infection (43.7%).

Finding of coagulase negative staphylococci in the herd with an increased number of somatic cells in milk and their antimicrobial susceptibility

Coagulase-negative staphylococci (CNS) are generally considered to be opportunistic pathogens. Controlling CNS mastitis is difficult because the epidemiology is not clear, and the CNS group consists of about 40 different Staphylococcus species. Therefore, the aim of this study was to determine the prevalence of coagulasenegative staphylococci in milk of the cows with subclinical mastitis, as well as to determine different CNS species isolated from quarter milk samples for their susceptibility to antimicrobials used commonly for mastitis therapy. On the farm where there was found an increase of somatic cells in bulk milk, 112 dairy cows were examined by mastitis test. From 52 udder quarters where mastitis test showed an increase of somatic cells, milk samples were taken for bacteriological examination. For isolating the causes of mastitis there was used blood agar. Identification of the causative agents of mastitis was carried out on the basis of colony appearance on blood agar and their physiological characteristics. Coagulasepositive staphylococci sensitivity which cause mastitis was tested by Kirby Bauer method. For susceptibility testing there were used commercially produced discs containing: 10 IU penicillin, amoxicillin/clavulanic acid (20 +10 μg), cloxacillin 25 μg, 30 μg amoxicillin, cephalexin 30 μg, ceftiofur 30 μg, 15 μg lincomycin, gentamicin and tetracycline 30 μg. The sensitivity of microorganisms was evaluated on the basis of inhibition zone diameter recommended by the manufacturer and was labeled as sensitive (S) moderately sensitive (I) or resistant (R). Coagulase-negative staphylococci were isolated from 61.53% of samples from cows with subclinical mastitis, making them the most common cause of subclinical mastitis. The highest resistance of coagulase-negative staphylococci was found to penicillin G (58.33% of isolates). Full sensitivity of coagulase-negative staphylococci was found to amoxicillin / clavulanic acid (100% of isolates), a good sensitivity to ceftiofur (83.33% of isolates), cefalexin (70.83% of isolates) and ceftriaxone (41.66% of isolates). [Projekat Ministarstva nauke Republike Srbije, br. TR 31086

Karakteristike izolata Pseudomonas spp. iz hrane životinjskog porekla

Pсеудомонaс спп. се као убиквитарни микроорганизам налази у спољашњој средини и сировом материјалу као контаминент. Из млека и меса су најчешће изоловани P.aеруgиносa и P.флуоресценс, али и P.путидa, P.фрagи, P.цоцхории и P.јенсен. Значај са аспекта хигијене хране се огледа у способности Pсеудомонaс спп. да синтетише термостабилне липолитичке и протеолитичке ензиме, који у хладном ланцу производње хране, могу да доведу до квара финалног производа. Као узрочник интрахоспиталних инфекција Pсеудомонaс спп. су често отпорни на велики број антимикробних лекова. Циљ овог рада је био да се испита антимикробна осетљивост изолата Pсеудомонaс спп. из хране и да се испита њихова протеолитичка и липолитичка активност. Испитано је укупно је по 20 изолата из сировог млека и 20 изолата са површине трупова закланих свиња. Сви изолати су били оксидаза и, каталаза позитивни, стварали су зелени пигмент на Триптон соја агару и имали су карактеристичан мирис. Такође, показивали су хемолизу на крвном, липолизу на трибутирин и протеолизу на агару са казеином. За испитивање антимикробне осетљивости коришћена је диск дифузиона метода за антибиотике пиперaциллин/тaзоbaцтaм, тикaрцилин, имипенем, меропенем, aзтреонaм, aмикaцин, gентaмицин, леvофлоксaцин и цефтaзидим. Осетљивост код изолата пореклом из млека је била 100%; 65%;100%;100%; 25%;75%; 30%; 65% и 100%, док је осетљивост изолата пореклом са трупова била 95%; 55%; 95%; 95%, 0%; 95%, 10%, 25% и 100%. Ни код једног изолата није доказана отпорност на цефтазидим што указује да није било ESBL сојева. MDR сојева отпорних на три или више антибиотика је било 2 (10%) из млека и 4 (20%) из меса, и то на тикарцилин, гентамицин, левофлоксацин код изолата из млека и тикарцилин, гентамицин, левофлоксацин код три и пиперацилин/тазобактам, тикарцилин, гентамицин, левофлоксацин једног изолата са трупова. Добијени резултати показују да псеудомонас може да контаминира храну животињског порекла и да проузрокује квар, али може да се разматра као извор гена резистенције.Pseudomonas spp. as ubiquitous microorganism is often found in environmental, raw materials as a contaminant. P.aeruginosa and P.fluorescens but also P.putida, P.fragi and P.cochorii may be isolated from milk and meet. From the view point of food hygiene, synthesis of termostable lipolytic and proteolytic enzymes in the cold chain of food processing, can cause the spoilage of final product. As a causative agent of nosocomial infections, Pseudomonas spp. are often resistant to a large number of antimicrobial substances. The aim of this study was to assess antimicrobial susceptibility of Pseudomonas spp. isolated from food and to evaluate their proteolytic and lipolytic activity. A total of 40 isolates (20 from raw milk; 20 from carcasses of slaughtered pigs) were examined. All of the isolates were oxidase and, catalase positive, produced a pigment on Tryptone Soy Agar and had a characteristic odor. They also showed hemolysis on Blood agar, lipolysis on Tributyrin and proteolysis on Casein agar. Antimicrobial susceptibility testing was performed by disk diffusion test for piperacillin/ tazobactam, ticarcillin, imipenem, meropenem, aztreonam, amikacin, gentamicin, levofloxacin and ceftazidime. The sensitivity of milk isolates was 100%; 65%; 100%; 100%; 25%; 75%; 30%; 65% and 100%, whereas the susceptibility of carcass-derived isolates was 95%; 55%; 95%; 95%, 0%; 95%, 10%, 25% and 100%. Susceptibility of milk and carcass-derived isolates to piperacillin/tazobactam, ticarcillin, imipenem, meropenem, aztreonam, amikacin, gentamicin, levofloxacin and ceftazidimewas 100%, 65%, 100%, 100%, 25%, 75%, 30%, 65%, 100% and 95%, 55%, 95%, 95%, 0%, 95%, 10%, 25%, 100%, respectively.There was no resistance to ceftazidime indicating no ESBL strains. MDR strains resistant to three or more antibiotics were 2 (10%) from milk and 4 (20%) from meat, namely ticarcillin, gentamicin, levofloxacin in milk isolates and ticarcillin, gentamicin, levofloxacin in three and piperacillin / tazobactam, ticarcillin, gentamicin, levofloxacin of one carcase isolate.In the present study, four MDR isolates were detected, 2 (10%) being isolated from milk and 4 (20%) from meat. Their resistance patterns were as follows: resistance to ticarcillin, gentamicin, levofloxacin (milk: n=2); resistance to ticarcillin, gentamicin, levofloxacin (carcasse: n=3), resistance to piperacillin/tazobactam, ticarcillin, gentamicin, levofloxacin (carcasse:n=1). In conclusion, psesudomonads might contaminate raw food of animal origin consequently leading to spoilage and considered as a reservoir of Pseudomonas spp. resistome

Characteristics of Pseudomonas spp. isolated from food of animal origin

Pseudomonas spp.as ubiquitous microorganism is often found in environmental raw materials as a contaminant. P. aeruginosa and P. fluorescens but also P. putida, P. fragi and P. cochorii may be isolated from milk and meet. From the view point of food hygiene synthesis of thermostable lipolytic and proteolytic enzymes in the cold chain of food production, can cause the spoilage of final product. As a causative agent of nosocomial infections, Pseudomonas spp. are often resistant to a large number of antimicrobial substances. Due to their ubiquity and ability to acquire resistance represents a potential risk to human health. The aims of the study were to assess antimicrobial susceptibility of Pseudomonas spp. isolated from food and to evaluate their proteolytic and lipolytic activity. A total of 40 isolates (20 from raw milk; 20 from carcasses of slaughtered pigs) were examined. All of the isolates were oxidase and, catalase positive, produced a pigment on Tryptone Soy Agar and had a characteristic odour. They also showed haemolysis on Blood agar, lipolysis on Tributyrin and proteolysis on Casein agar. Antimicrobial susceptibility testing was performed by disk diffusion test on piperacillin/ tazobactam, ticarcillin, imipenem, meropenem, aztreonam, amikacin, gentamicin, levofloxacin and ceftazidime. The sensitivity of milk isolates was 100%; 65%; 100%; 100%; 25%; 75%; 30%; 65% and 100%, whereas the susceptibility of carcass-derived isolates was 95%; 55%; 95%; 95%, 0%; 95%, 10%, 25% and 100%. Susceptibility of milk and carcass-derived isolates to piperacillin/tazobactam, ticarcillin, imipenem, meropenem, aztreonam, amikacin, gentamicin, levofloxacin and ceftazidime was 100%, 65%, 100%, 100%, 25%, 75%, 30%, 65%, 100% and 95%, 55%, 95%, 95%, 0%, 95%, 10%, 25%, 100%, respectively. There was no resistance to ceftazidime indicating no ESBL strains. MDR strains resistant to three or more antibiotics were 2 (10%) from milk and 4 (20%) from meat, namely ticarcillin, gentamicin, levofloxacin in milk isolates and ticarcillin, gentamicin, levofloxacin in three and piperacillin / tazobactam, ticarcillin, gentamicin, levofloxacin of one carcase isolate. In the present study, four MDR isolates were detected, 2 (10%) being isolated from milk and 4 (20%) from meat. Their resistance patterns were as follows: resistance to ticarcillin, gentamicin, levofloxacin (milk: n=2); resistance to ticarcillin, gentamicin, levofloxacin (carcase: n=3), resistance to piperacillin/tazobactam, ticarcillin, gentamicin, levofloxacin (carcase: n=1). In conclusion, pseudomonads might contaminate raw food of animal origin consequently leading to spoilage and considered as a reservoir of Pseudomonas spp. resistome

Occurrence of biofilm forming coagulasepositive isolates in case of subclinical mastitis

Coagulasepositive staphylococci (CPS) are the leading health and economic problem in primary milk production. Some strains are cappable to form a biofilm causing presistent intramammary infestions, easily spreading to the udder of healthy cows and contaminateing the environment. By excretion into milk, they can enter the food chain and pose a risk to human health. Determination of the ability to form a biofilm during isolation and identification of CPS in short period of time could improve good veterinary practice. The aim of this work was to determine the ability to form biofim in CPS isolates from cows mastitic milk. From 56 quarter milk samples with > 500.000 cells/mL, CPS were isolated from 29 (51.78%) samples. The abilty of CPS to form biofilm was examined by Congo Red Agar (CRA) method and Crystal Violet assay. Based on the colour and consistensy of the colonies at CRA, it was detected that out of 29 CPS isolates 5 (17.24%) isolates produced slime, 16 (55.17%) were suspected producers and 8 (27.5%) isolates did not produce the slime. Estimation of biofilm production by microtiter plate method was performed mesering the optical density at 630 nm (OD630) and showed that 8 (27.5%) isolates were high producers, 12 (34.8%) moderate, 6 (20.60%) weak and 3 (10.30%) isolates did not produced biofilm. It can be concluded that Congo red agar method may be used as a rapid method for detection of biofilm producing CPS isolates

Spoilage microorganisms in food

Производња хране представља значајну привредну делатност и улогу у снабдевању становништва животним намирницама, док квар хране има за последицу велике економске губитке услед одбацивања хране као неупотребљиве за исхрану и трошкова уклањања органског отпада. Према новијим истраживањима 30% произведене хране заврши на светским депонијама, где подлеже трулежним процесима и распадању, при чему се ослобађају гасови, међу којима и метан. Према дефиницији квар хране представља различите процесе, који узрокују да храна буде непожељна или неприхватљива за људску употребу због промене сензорних карактеристика. Квар хране се може дефинисати и као "свака сензорна промена (тактилна, визуелна, олфактивна или промена укуса)" коју конзумент сматра да је неприхватљива. Квар може настати у било којој фази ланца хране. Све врсте квара се могу сврстати у следеће групе: биохемијски (ензимски), микробиолошки, хемијски и технолошки квар. Микробиолошки квар хране може бити проузрокован узрочницима као што су бактерије, квасци и плесни. Хемијски квар подразумева промене проузроковане хемијским и физичко- хемијским реакцијама који настају услед штетног утицаја фактора спољне средине (високе температуре, ваздух, влага, светлост, pH итд). Често је тешко утврдити да ли се ради о искључиво хемијском, биохемијском или микробиолошком квару, јер се промене одвијају паралелно. Под појмом „технолошки квар“ подразумева се у ширем смислу квар проузрокован грешкама током технолошког процеса добијања хране. Према подацима истраживања, које је спровео Центар за унапређење животне средине 2019.године, у Републици Србији је одбачено 247.000 t хране, што на дневном нивоу износи 676 t, и може се прерачунати да један становник у току године дневно баци 35 kg хране. Од хране се највише баца хлеб (10,18 kg), месо (7,18 kg) и млеко (6,74 l), а знатно мање храна биљног порекла - воће (5,7 kg ) и поврће (5,33 kg). Kao разлог због којег се храна баца на првом месту се наводи квар (67%), затим одбијање конзумената да једу храну, која није свежа (17%) и мишљење потрошача да храна није безбедна (11%). Један од највећих изазоваза савремену индустрију хране јесте како сачувати намирнице од квара. Због свог хемијског састава храна, посебно храна животињског порекла (млеко и производи од млека; месо и производи од меса) представља добру средину за раст и размножавање микроорганизама, стога је за циљ овог рада постављено да се укаже на значај микроорганизама, који могу да доведу до квара хране. У раду ће бити описане врсте микроорганизама, њихове карактеристике и промене које доводе у храни животињског порекла.Food production represents a significant economic activity and has a role in supplying the population with food, while food spoilage results in large economic losses due to the rejection of food as unusable and the costs of disposing of organic waste. According to recent study, 30% of produced food ends up in the world's landfills, where undergoes putrefaction and decomposition, releasing gases, including methane. Food spoilage is defined as various processes, which cause food to be undesirable or unacceptable for human use due to a changes in sensory characteristics. Food spolage can also be defined as "any sensory change (tactile, visual, olfactory or aroma change)" that the consumer considers unacceptable. Spoilage can occur at any stage along food chain. All types of spoilage can be classified into the following groups: biochemical (enzymatic), microbiological, chemical and technological spoilage. Microbiological spoilage of food can be caused by pathogens such as bacteria, yeasts and molds. Chemical spoilage means changes caused by chemical and physico-chemical reactions that occur due to the harmful influence of environmental factors (high temperatures, atmosphere, humidity, light, pH, etc.). It is often difficult to determine whether it is a strict chemical, biochemical or microbiological spoilage, because the changes take place in parallel. The term "technological spoilage" means in a broader sense a spoilage caused by mistakes during the technological process in food production. According to the research conducted by the Center for Environmental Improvement in 2019 in the Republic of Serbia, 247,000 tons of food were discarded, of which is 676 tons on a daily basis, and it can be calculated that one inhabitant throws 35 kg of food per year. Bread (10.18 kg), meat (7.18 kg) and milk (6.74 l) are the most discarded food, while much less food of plant origin - fruits (5.7 kg) and vegetables (5.33 kg). The reason for discarding the food in the first place is the spoilage (67%), then the refusal of consumers to eat the food, which is not fresh (17%) and the opinion of consumers that the food is not safe (11%). One of the biggest challenges for the modern food industry is how to save food from spoilage. Due to its chemical composition, food, especially food of animal origin (milk and dairy products; meat and meat products) is a good environment for the growth and muliplication of microorganisms, so the aim of this paper is to point out the importance of microorganisms that can cause food spoilage. The paper will describe the types of microorganisms, their characteristics and the changes they cause in food of animal origin