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Öğe Antimicrobial activities of N-(2-hydroxy-1-naphthalidene)-amino acid(glycine, alanine, phenylalanine, histidine, tryptophane) Schiff bases and their manganese(III) complexes(Springer Netherlands, 2004) Logoğlu, Elif; Arslan, Seza; Sarı, Nurşen; Şakıyan, NazmiyeThe in vitro antibacterial and antifungal activities of five different amino acid Schiff bases derived from the reaction of 2-hydroxy-1-naphthaldehyde with glycine, L-alanine L-phenylalanine, L-histidine, L-tryptophane and the manganese(III) complexes of these bases were investigated. Structures of the Schiff bases were proven by 1 H-NMR. In vitro activities against some Gram-positive (Staphylococcus aureus and Bacillus polymyxa) and Gram-negative (Escherichia coli) bacteria and the fungus Candida albicans were determined. The antimicrobial activities tended to decrease with the increasing size of the amino acid residues.Öğe Antimicrobial activity of tetra substituted benzene derivatives(2005) Loğoğlu, E.; Arslan, Seza; Öktemer, A.2,4,6-triklor tribrom and triiyot anilinlerden sentezlenmiş olan [1-klor (veya brom veya iyot)-2,4,6-triklor vel-klor (veya brom veya iyot)-2, 4,6-tribrom ve 1-klor (veya brom veya iyot)-2,4, 6-triiyot benzen] gibi tetra substitue benzen türevlerinin in vitro antibakteriyel ve antifungal özellikleri incelenmiştir. Tetrasubstitute benzene türevleri sentezlenmiş, IR ve NMR gibi spektroskopik yöntemlerle yapıları aydınlatılmıştır. Antibakteriyel ve antifungal aktiviteler; Minumum inhibisyon konsantrasyonu (MIC) metodu ile gram-pozitif bakteriler ( Staphylococcus aureus ATCC 25923, Bacillus subtilis ATCC 6633) ve gram-negatif bakteriler (Yersinia enterocolitica ATCC 1501 Escherichia coli ATCC 11230) ve kendi koleksiyonumuzdan olan maya {Candida albicans) bakterilerine karşı ölçülmüştür. Bu bileşiklerde halojen sübstitüentin büyüklüğü arttıkça antimikrobiyal aktivite azalmaktadır.Öğe Antimicrobial activity studies on some piperidine and pyrrolidine substituted halogenobenzene derivatives(Taylor & Francis Ltd, 2006) Arslan, Seza; Logoğlu, Elif; Öktemer, AtillaThe in vitro antibacterial and antifungal activities of the compounds synthesised from some 1,2,3,5-tetrahalogeno benzenes in presence of sodium piperidide and sodium pyrrolidide (2,6-dipiperidino-1,4-dihalogenobenzenes; 2,6-dipyrrolidino-1,4-dibromobenzene; 2,4,6-tripyrrolidino chlorobenzene; and 1,3-dipyrrolidino benzene) were investigated. The in vitro antimicrobial activities were screened against the standard strains: Staphylococcus aureus ATCC 25923 and Bacillus subtilis ATCC 6633 as Gram positive, Yersinia enterocolitica ATCC 150 1, Escherichia coli ATCC 11230 and Klebsiella pneumoniae as Gram negative, and Candida albicans as yeast-like fungus. Compounds (3, 5, 6, 7) inhibited the growth of all the test strains at MIC values of 32-512 mu g/ml. None of the four compounds (1, 2, 4, 8) studied showed antimicrobial activity against any of the test strains within the MIC range 0.25-512 mu g/ml.Öğe Antimicrobial resistance and esbl prevalence in escherichia coli from retail meats(Wiley, 2011) Arslan, Seza; Eyi, AylaIn the study, Escherichia coli isolates were recovered from 72 (42.9%) of the 168 retail meat samples. Overall, 48 (66.7%) of the poultry meat, 13 (18.1%) of the ground beef and 11 (15.3%) of the meat samples were positive for E. coli. All E. coli isolates using the disk diffusion method were tested for their resistance patterns toward 16 commonly used antimicrobial agents. In general, the most frequently encountered form of resistance in all samples was resistance to erythromycin (91.7%), tetracycline (55.6%), ampicillin (50%), sulphamethoxazole/trimethoprim (45.8%) and piperacillin (41.7%). None of the isolates had resistance to six antimicrobials tested. A total of 94.4% of the isolates were resistant to one or more antimicrobial agents, and multiple resistance to three or more antimicrobial drugs was 56.9%. Extended-spectrum beta-lactamases production in meat isolates was also found in 13.9% of E. coli isolates by the phenotypic confirmatory test and in 11.1% of E. coli isolates by the double disk synergy test.Öğe Antimicrobial resistance of Staphylococcus aureus isolated from human and food against Linezolid, Quinupristin-Dalfopristin, Quinolones and Imipenem(Academic Journals, 2012) Arslan, Seza; Özdemir, FatmaStaphylococcus aureus is a versatile pathogen of humans and animals that has evolved resistance to all classes of antimicrobials. A total of 293 S. aureus isolates including 71 obtained from human and 222 recovered from food against crucial antimicrobial agents used in human and veterinary practice were examined for the antimicrobial resistance profiles. The in vitro activities of new agents (linezolid and quinupristin-dalfopristin), quinolones (ofloxacin, norfloxacin, levofloxacin, moxifloxacin) and imipenem against the isolates were performed by standard disk diffusion method. The 293 isolates demonstrated very low levels of resistance to imipenem (0.7%), followed by quinupristin-dalfopristin (1.7%) but had the highest activity against linezolid (6.8%) and moxifloxacin (5.5%). Over 9.9% of clinical isolates showed resistance to three or more antimicrobial agents. Only 1.8% of food isolates were multidrug resistant (>= 3 antibiotics). The differences between clinical and food isolates in the results of antimicrobial resistance were statistically significant. Besides, comparing the resistance to each antimicrobial agent between the two group isolates, there were statistically significant differences (P<0.05). Because S. aureus has a remarkable propensity to develop or acquire resistance to antimicrobial agents, it is important to continually monitor antimicrobial susceptibilities of isolates from clinical and food sources.Öğe Biofilm formation, icaABCD genes and agr genotyping of Staphylococcus aureus from fish and ground beef(Akademiai Kiado ZRT, 2021) Özdemir, Fatma; Arslan, Seza; Eken, Ceren BetülA total of 46 Staphylococcus aureus isolates from fish and ground beef were tested for the agr types, icaABCD genes, and biofilm formation at 12, 25 and 37 8 degrees C by the microtiter plate and the MTT assays. All isolates were positive for the icaABD genes, while 97.8% were positive for the icaC. All isolates produced biofilms at 37 and 25 8 degrees C, but 93.5% of them were also biofilm producers at 12 8 degrees C. There was no significant difference in biofilm formation between 25 and 37 8C using the crystal violet assay (P > 0.05). However, statistically significant differences were detected between 12 and 25 8 degrees C as well as 12 and 37 8 degrees C (P < 0.05). All isolates were significantly different in biofilm production by the MTT assay at all tested temperatures. Furthermore, a relationship between the presence of the icaABCD genes and biofilm formation was observed. The agr type I was the most prevalent (54.4%) among the isolates, followed by agr type II (41.3%) and agr type III (9.6%). In this study, the S. aureus isolates exhibited biofilm formation ability responsible for persistence of bacteria in foods, which may lead to food spoilage and human health problems.Öğe Biofilm formation, siderophore production, virulence-associated genes and genetic diversity of Yersinia enterocolitica isolated from foods(Hellenic Veterinary Medical Soc, 2022) Özdemir, Fatma; Arslan, SezaYersinia enterocolitica is a foodborne pathogen widely found in nature and foods. The ability of this organism to multiply at refrigeration temperatures in food products with a prolonged shelf-life renders it a potential health risk for consumers. Y. enterocolitica isolates from foods were investigated for biofilm formation and siderophore production at different temperatures (12, 25 and 37 ??C) using the microtiter plate and CAS agar plate meth-ods, respectively. The isolates were also evaluated with PCR for the presence of virulence genes and rep-PCR for genetic diversity. Most of the isolates showed high capability to form biofilm at all temperatures after 24 and 48 h of incubation. The results at 12 and 25 ??C (P < 0.05) as well as at 25 and 37 ??C (P 0.05) showed a statistically significant difference in quantification of biofilm formation after 24 h; however, no difference was observed between findings at 12 and 37 ??C (P 0.05) after 48 h of incubation; conversely, no significant difference was observed between 12 and 25 ??C (P 0.05). Strong biofilm-producing isolates at 12 ??C were more prevalent at 48 h than at 24 h. Siderophore production was observed in 83.3% and 100% of the isolates at 25 and 37 ??C, respectively. However, no isolate produced siderophores at 12 ??C. Genes myfA, fepA, fepD, fes, hreP, tccC and ymoA were detected in 16.7%, 33.3%, 100%, 100%, 44.4%, 5.6%, and 33.3% of the isolates, respectively. The rep-PCR revealed a high level of genetic differentiation among the isolates. The results indicate that foods of animal origin may act as a potential vehicle for dissemination in the community of Y. enterocolitica strains producing biofilm and siderophore and carrying virulence-associated genes.Öğe Biofilm production and antimicrobial susceptibility profiles of bacillus spp. from meats(2018) Özdemir, Fatma; Arslan, SezaThe genus Bacillus is frequently found in soil, water, and food. Bacillus cereus and Bacillus anthracis are the main pathogens causing foodborne diseases and serious infections in humans. A total of 52 Bacillus spp. from meat samples was tested for determination of biofilm production, antimicrobial resistance pattern, and beta-lactamase activity. The 24 (46.1%) Bacillus isolates were found to be for biofilm production. Of the 24 (46.1%) biofilm producer Bacillus isolates, 13 (25%), 6 (11.5%) and 5 (9.6%) were considered as strong, moderate and weak biofilm producer, respectively. The most common species for the production of biofilm was Bacillus thuringiensis (80%). Antimicrobial disk susceptibility tests of Bacillus spp. revealed high resistance to ampicillin (84.6%) followed by penicillin (75%), cefepime (34.6%), and cefoxitin (26.9%). A multidrug resistance to at least 3 or more antimicrobials was observed in the 25 isolates (48.1%). All Bacillus spp. were sensitive to vancomycin, gentamicin, amikacin, ciprofloxacin, and imipenem. The susceptibility rate to streptomycin, chloramphenicol, and trimethoprim-sulphamethoxazole was 94.2%. Among the isolates, the 6 (11.5%) isolates were found to be sensitive to all antimicrobial agents tested. Besides, only one isolate from meat was found to be positive for beta-lactamase test. The existence of biofilm production as a virulence factor and of multidrug resistance in bacteria isolated from food should not be underestimated in terms of food safety, public health, and economic concerns.Öğe Biological activities of some natural compounds from sideritis sipylea boiss(Wiley, 2006) Loğoğlu, Elif; Arslan, Seza; Öktemer, Atilla; Şakıyan, İffetIn this work, several diterpenes including siderol, linearol and epicandicandiol were isolated from Sideritis sipylea Boiss collected from Izmir-Karaburun-Akdag, Turkey. In addition, diacetate derivatives of linearol and epicandicandiol were obtained. The antimicrobial activites of all these compounds against the bacteria Staphylococcus aureus (ATTC 25923), Bacillus subtilis (ATCC 6633), Escherichia coli (ATCC 11230), Pseudomonas aeruginosa (ATCC 27853) and the fungus Candida albicans (ATCC 90028) were studied. Antimicrobal activity was measured by the well-diffusion method. Except for C. albicans all microorganisms were tested against antibiotic discs in comparison with the studied compounds.Öğe Expression of blaA and blaB and Susceptibility to Penicillins and Cephalosporins in Yersinia enterocolitica from Different Foods(Istanbul University Press, 2020) Ozdemir, Fatma; Arslan, Seza; Erturk, Hafize GizemObjective: Yersinia enterocolitica which is an important foodborne pathogen causing illness in humans is an extremely heterogeneous species consisting of different subtypes. It has the intrinsic resistance to ?-lactam antibiotics because of the production of ?-lactamases, BlaA and BlaB. Y. enterocolitica exhibits variable susceptibilities to ?-lactams. Materials and Methods: The expression of the blaA and blaB genes by polymerase chain reaction, and the susceptibility to some ?-lactams including penicillins and cephalosporins using the broth microdilution and disk diffusion methods were determined. A total of 18 Y. enterocolitica isolates were examined. Results: Overall, 33.3% of these isolates carried the blaA and blaB genes, all of which were recovered from chicken meat. The wide range of MIC for ampicillin (?2-128 ?g/mL) and ceftazidime (?0.0625-2 ?g/mL) was also observed. Of the Y. enterocolitica isolates, 55.6% were resistant to ampicillin (?32 ?g/mL) while the remaining isolates (44.4%) were susceptible to ampicillin (? 8 ?g/mL). All isolates were susceptible to ceftazidime at the concentration tested. According to the disk diffusion test, 55.6% and 33.3% of the isolates were resistant to ticarcillin and cefoxitin, respectively. No resistance to piperacillin and ceftriaxone was found. Conclusion: The results showed that the presence of the blaA and blaB genes and intrinsic resistance against penicillins and cephalosporins were variable among Y. enterocolitica food isolates. Furthermore, the blaA and blaB genes were expressed in most of the resistant isolates to ?-lactams, which may indicate the contribution of the genes to the drug resistance. © Istanbul University Press. All rights reserved.Öğe Extended spectrum beta-lactamases in Escherichia coli strains isolated from homemade white cheeses: prevalence and antibiotic susceptibility(Springer, 2008) Arslan, Seza; Özdemir, FatmaThe present study included 223 E. coli strains isolated from homemade white cheeses and was undertaken to determine the prevalence of extended spectrum beta-lactamases (ESBL)-producing strains and antibiotic susceptibility. ESBL production was detected using three methods: the NCCLS disk diffusion test, the double disk synergy test and the NCCLS confirmatory test. By the disk diffusion test, 48% isolates were determined as potential ESBL producers. ESBL production by the double disk test and the phenotypic confirmatory test was found to be 16.1 and 9.9%, respectively. Susceptibility of all isolates against 16 antimicrobials was tested by the disk diffusion method. All strains were imipenem- and cefepime-susceptible. Susceptibility of E. coli to ceftazidime, ceftriaxon, cefotaxime and aztreonam was found to be 93.7, 96.4, 81.2, 90.6%, respectively. The least effective antibiotics were ampicillin with a rate of 68.6% and cefuroxime with a rate of 69.1%.Öğe Genotypic and phenotypic virulence characteristics and antimicrobial resistance of Yersinia Spp. Isolated from meat and milk products(Wiley, 2015) Özdemir, Fatma; Arslan, SezaA total of 300 food samples including 180 milk and 120 meat products have been examined for the presence of Yersinia spp. using the ISO 10273 and the cold enrichment method. The overall prevalence of Yersinia spp. was 84 (28%). Yersinia enterocolitica was isolated from 18 (6%) of the 300 samples. The other Yersinia species were detected in the samples Yersinia rohdei 15 (5%), Yersinia intermedia 14 (4.7%), Yersinia pseudotuberculosis 12 (4%), Yersinia ruckeri 12 (4%), Yersinia mollaretii 5 (1.7%), Yersinia bercovieri 4 (1.3%), and atypical Yersinia spp. 4 (1.3%). The conventionally identified Y. enterocolitica strains were also confirmed by the 16S rRNA gene sequencing. All Y. enterocolitica strains biotyped as 1A had negative results in the phenotypic virulence tests. The 84 Yersinia strains were also examined genotypically for the presence of virulence genes. None of the Y. enterocolitica and other Yersinia strains contained the ail, ystA, yadA, and virF except only 1 Y. intermedia and 2 Y. enterocolitica strains that were found to be positive for ystB. Antimicrobial resistance of 84 Yersinia to 16 antimicrobial agents was determined by the disk diffusion method. All strains were sensitive to tobramycine and imipenem while resistant to clindamycin. Although 84.5% of the strains were resistant to at least 3 or more antimicrobial agents, 64.3% of them were resistant to 4 or more antimicrobial agents. Practical Application The present study has indicated that the presence of some Yersinia spp., including Y. enterocolitica strains found to be biotype 1A in meat and milk products, which have virulence factors and multi-drug resistance, may be regarded as a potential health hazard for consumers depending upon the state of their immune system. Therefore, the distribution of virulence markers and antibiotic resistance in Yersinia strains from food sources should be considered and monitored concurrently.Öğe In vitro antimicrobial activity studies of thioethoxy- and thiophyenoxyhalobenzene derivatives(Freund Publishing House Ltd, 2006) Logoglu, Elif; Arslan, Seza; Oektemer, AtillaThe in vitro antibacterial and antifungal activities of thioethoxy- and thiophyenoxyhalobenzene derivatives were investigated. Thioethoxy- and thiophyenoxyhalobenzenedervatives synthesized and identified by spectroscopic means IR and NMR and elemental analysis. The antibacterial and antifungal activities were measured by Minumum inhibition concentration (MIC) method against gram-positive bacteria i.e. Staphylococcus aureus ATCC 25923, Bacillus subtilis ATCC 6633; Gram-negative bacteria as Yersinia enterocolitica ATCC 1501, Escherichia coli ATCC 11230, Klebsiella pneumoniae and fungus as Candida albicans from our strain collection. Antimicrobial activies of these compounds tended to increase with size and numerous and kinds of halogene and thiogroups substitutents.Öğe In vitro antimicrobial activity studies of thioethoxy-and thiophyenoxyhalobenzene derivatives(Freund Publishing House Ltd, 2006) Loğoğlu, Elif; Arslan, Seza; Öktemer, AtillaThe in vitro antibacterial and antifungal activities of thioethoxy- and thiophyenoxyhalobenzene derivatives were investigated. Thioethoxy- and thiophyenoxyhalobenzenedervatives synthesized and identified by spectroscopic means IR and NMR and elemental analysis. The antibacterial and antifungal activities were measured by Minumum inhibition concentration (MIC) method against gram-positive bacteria i.e. Staphylococcus aureus ATCC 25923, Bacillus subtilis ATCC 6633; Gram-negative bacteria as Yersinia enterocolitica ATCC 1501, Escherichia coli ATCC 11230, Klebsiella pneumoniae and fungus as Candida albicans from our strain collection. Antimicrobial activies of these compounds tended to increase with size and numerous and kinds of halogene and thiogroups substitutents.Öğe Inhibitory activity of natural isolates of lactic acid bacteria from raw milk against hazardous microbes(A V A Agrarverlag, 2005) Arslan, Seza; Uraz, GüvenInhibitory activity of 32 strains of lactic acid bacteria isolated from raw milk was evaluated for their ability to inhibit some hazardous microbes. The isolates consisted of the genera Lactobacillus (43.75%), Pediococcus (28.12%), Streptococcus (15.62%), and Leuconostoc (12.50%). All the strains tested inhibited one or more indicator strains. Yersinia enterocolitica was inhibited by the all lactic acid bacteria. Of the lactic acid bacterial isolates, 93.75% exhibited inhibitory activity against Listeria monocytogenes. The indicator strains belonging to the same genus, Bacillus subtilis and B. cereus, were inhibited at the same level by 87.50% of the test strains. Staphylococcus aureus was also inhibited by 81.25% of the test strains, whereas Str. faecalis was inhibited at the lowest level by 62.59% of the lactic acid bacteria isolated from raw milk.Öğe Investigation of Escherichia coli O157 in Turkish homemade white cheese(2013) Arslan, Seza; Özdemir, FatmaVerositotoksin üreten Escherichia coli (VTEC) gıda zehirlenmeleri gibi ciddi halk sağlığı risklerine neden olan önemli patojendir. Çiğ süt ile çiğ sütten ya da yeterli derecede pastörize edilmemiş sütten yapılan peynirler VTEC serotip E. coli O157 enfeksiyonları için potansiyel bir kaynak teşkil etmektedir. Bu çalışmada, kırsal kesimde üretilen toplam 245 adet Türk ev yapımı beyaz peynir örneği çeşitli açık halk pazarlarından toplanmıştır. Toplanan örnekler E. coli serotip O157’nin varlığı açısıdan araştırılmıştır. Sefksim-tellürite (CT) ihtiva eden sorbitol MacConkey (CT-SMAC) besiyerinden sorbitolü fermente etmeyen toplam 21 koloni E. coli O157 varlığı açısından şüpheli izolat olarak tespit edildi. E. coli O157 varlığı açısından şüpheli izolatlar ticari E. coli O157 lateks aglütinasyon test kitine üreticinin talimatları doğrultusunda tabi tutuldu. Türk halkı tarafından sevilerek tüketilen toplam 245 Türk ev yapımı beyaz peynirin hiçbirinde E. coli O157 varlığı tayin edilmedi. Sonuç olarak, bu sevilen gıdada E. coli O157’nin yokluğu sevindirici bir tespittir. Bununla beraber, gıdalarda tüketici sağlığı için önemli bir gıda kaynaklı patojen olan E. coli O157:H7’nin varlığına yönelik titiz incelemenin gerçekleştirilmesi tavsiye edilir.Öğe Molecular Characterization and Biofilm Formation of Escherichia coli from Vegetables(2021) Özdemir, Fatma; Arslan, SezaEscherichia coli can cause diarrheal and extraintestinal illnesses in humans. Diarrheagenic E.coli can be transmit to human through consumption of contaminated food, including vegetables.Biofilm produced by E. coli during food processing plays a role in development of foodborneillnesses. Vegetables have often been involved in diarrheal E. coli infections. A total of 40 E.coli isolates from vegetables were tested to determine biofilm formation at 12°C, 25°C and37°C by the crystal violet and MTT assays. All isolates were performed for the productionof curli fimbriae and cellulose associated with biofilm formation on Congo red agar. Biofilmformation by the crystal violet assay at 37°C, 25°C and 12°C was detected in 87.5%, 70%and 70% of the isolates, respectively. The biomass and viability of E. coli biofilms were similaraccording to the results of crystal violet and MTT assays. Biofilm formation among the E. coliisolates using the crystal violet and MTT assays showed a statistically significant differencebetween 12°C and 25°C as well as 12°C and 37°C (p < 0.05). However, no significantdifference between 25 and 37°C (p > 0.05) was obtained. Three different morhotypes (bdar,pdar and saw) were identified based on the expression of curli fimbriae and cellulose. Theincidence of the bdar morhotype was 27.5% and 50% at 25°C and 37°C, respectively.Prevalence of the pdar morphotype was 50% and 70% at 25°C and 37°C, respectively. At 25°C,only one isolate (2.5%) showed the saw morphotype. All isolates tested expressed curli fimbriaeor cellulose, only three of which were non-biofilm producer using the crystal violet assay. Thisstudy demonstrated that the presence of biofilm forming E. coli isolates in vegetables may causea risk to human health and food safety.Öğe Molecular characterization and detection of enterotoxins, methicillin resistance genes and antimicrobial resistance of Staphylococcus aureus from fish and ground beef(Polska Akad Nauk, Polish Acad Sciences, Univ Warmia & Mazury Olsztyn, 2017) Arslan, Seza; Özdemir, FatmaA total of 120 samples including 40 freshwaterfish(Oncorhynchus mykiss), 40 seawater fish (Sparus aurata) and 40 ground beef samples were examined for the presence of Staphylococcus aureus. The isolates were identified using biochemical tests and a PCR for the species-specific fragment (Sa442) and thermonuclease gene (nucA). The presence of staphylococcal enterotoxin genes (sea, seb, sec, sed and see), toxin genes (eta, etb, tsst), methicillin resistance gene (mecA) and some phenotypic virulence factors was also tested. Genotypic characterization of the isolates was analyzed by PCR-RFLP of the coa gene. Overall, 36 (30%) meat samples were contaminated with S. aureus. Of the 36 isolates, 3 (8.3%) were found to be positive for enterotoxin genes. Only 1 isolate (5.9%) from ground beef had the sea gene. In addition, 1 (12.5%) of the freshwater fish and 1 (9.1%) of the seawater fish carried both the sea and sed genes. The presence of seb, sec, see, eta, etb and tsst was not detected among the isolates of S. aureus. The amplified coa gene revealed five different clusters. Seven and six distinct RFLP patterns were obtained with AluI and HaeIII digestion, respectively. All isolates were found to be positive for slime, hemolytic and DNase activity while 41.7% of them were beta-lactamase positive. The presence of methicillin resistance was neither detected by PCR nor the disk diffusion method. A total of 94.4% of the isolates were resistant to at least one antimicrobial while 44.4% of them were resistant to at least two or more antimicrobials.Öğe Molecular characterization and toxin profiles of bacillus spp. isolated from retail fish and ground beef(Wiley, 2019) Özdemir, Fatma; Arslan, SezaBacillus species are common in the environment due to their spore-forming ability and nutritional versatility and cause food contamination. Bacilli play a significant role in foodborne illnesses and food spoilage. In this study, 52 Bacillus isolates from retail fish and ground beef were identified and differentiated based on 16S rRNA, gyrB, and rpoB gene sequencing. The presence of genes encoding emetic toxin (ces), hemolytic enterotoxin hemolysin BL (hbl), nonhemolytic enterotoxin (nhe) and cytotoxin K (cytK1) was assessed in all Bacillus isolates. The ability of the Bacillus isolates to produce several extracellular enzymes that contribute to pathogenicity and food spoilage was investigated. The 16S rRNA, rpoB, and gyrB gene sequence similarities of the Bacillus isolates tested were 96.1%, 83.2%, and 77.5%, respectively. The gyrB gene demonstrated a higher degree of sequence variation than the 16S rRNA and rpoB genes. The prevalence of Bacillus isolates producing at least two of the genes of the HBL and NHE complexes was 23.1% and 15.4%, respectively. Of the B. cereus isolates, 10 (41.7%) possessed two or more enterotoxin genes. None of the isolates carried the ces and cytK1 genes. All isolates were positive for the production of enzymes such as protease, lipase, gelatinase, and DNase. However, only 92.3% of the tested isolates were positive for amylase. In conclusion, our results revealed that the presence of genes involved in toxin production and enzyme production in meat-originated B. cereus and other Bacillus isolates may cause spoilage of food and pose a health risk for consumers.Öğe Occurrence and antimicrobial resistance of Staphylococcus aureus in homemade cheeses(A V A Agrarverlag, 2011) Arslan, Seza; Özdemir, FatmaStaphylococcus aureus is one of the most important foodborne pathogens. Milk and dairy products are often contaminated with this bacterium. In the present study, the occurrence of S. aureus was determined in homemade cheese samples collected from various public bazaars. Of 200 samples examined, 135 (67.5%) were positive for S. aureus. A total of 217 S. aureus isolates from 135 contaminated cheese samples were isolated and identified. All S. aureus isolates were analyzed for production of slime, DNase and beta-lactamase and their antimicrobial resistance pattern. Sixteen strains of S. aureus isolates (7.4%) were found to be slime producers by Congo red agar method, 175 strains (80.6%) were DNase positive. Beta-lactamase producing isolates were detected in 66 (30.4%) isolates. Susceptibility of cheese isolates against 15 different antimicrobial agents was tested using disc diffusion method. S. aureus isolates had resistance to one or more antibiotics, the highest resistance to ampicillin (41%), penicillin (40.1%) and tetracycline (38.7%) among the various antimicrobial agents. A total of 25.8% of S. aureus isolates were multiresistant to three or more antimicrobial agents. S. aureus isolates recovered from cheese which have virulence factors may be important due to potential risk of foodborne transmission to the human microflora via foods.
