Impact of lactic acid bacteria strains against Listeria monocytogenes biofilms on various food-contact surfaces.

Listeria monocytogenes is one of the most important foodborne pathogens, causing listeriosis, a disease characterized by high mortality rates. This microorganism, commonly found in food production environments and transmitted to humans by consuming contaminated food, has the ability to form biofilms by attaching to a wide variety of surfaces. Traditional hygiene and sanitation procedures are not effective enough to completely remove L. monocytogenes biofilms from food-contact surfaces, which makes them a persistent threat to food safety. Alternative approaches to combating Listeria biofilms are needed, and the use of lactic acid bacteria (LAB) and their antimicrobial compounds shows promise. The present study investigated the effect of Lactobacillus strains, previously isolated from various foods and known to possess antimicrobial properties, on the biofilm formation of L. monocytogenes on three different food-contact surfaces. To study L. monocytogenes IVb ATCC 19115 type, culture was preferred to represent serotype IVb, which is responsible for the vast majority of listeriosis cases. The results demonstrated that cell-free supernatants (CFSs) of LAB strains inhibited biofilm formation by up to 51.57% on polystyrene, 60.96% on stainless steel, and 30.99% on glass surfaces. Moreover, these CFSs were effective in eradicating mature biofilms, with reductions of up to 78.86% on polystyrene, 73.12% on stainless steel, and 72.63% on glass surfaces. The strong inhibition rates of one strain of L. curvatus (P3X) and two strains of L. sakei (8.P1, 28.P2) used in the present study imply that they may provide an alternate technique for managing Listeria biofilms in food production environments.

Detection of Listeria Species by Conventional Culture-Dependent and Alternative Rapid Detection Methods in Retail Ready-to-Eat Foods in Turkey.

Foodborne pathogens, like Listeria monocytogenes, continue to inflict substantial financial losses on the food industry. Various methods for detecting Listeria in food have been developed and numerous studies have been conducted to compare the different methods. But, in recent years, new Listeria species have been identified, and currently the genus comprises 26 species. Therefore, it would be a more accurate approach to re-evaluate existing detection methods by considering new species. The present investigation involved the analysis of 42 ready-to-eat (RTE) foods, encompassing a variety of food categories, such as mezes, salads, dairy products, and meat products, with the aim of ascertaining the presence of Listeria. Among the traditional culture-dependent reference methods, the ISO 11290 method was preferred. The process of strain identification was conducted with the API Identification System. Furthermore, to ascertain the existence of L. monocytogenes and Listeria spp., the samples underwent additional analysis employing the VIDAS Immunoassay System, ELISA, and RT-PCR methodologies. Thus, four alternative approaches were employed in this study to compare not only the different methods used to determine Listeria while taking into account the newly identified Listeria species, but also to assess the compliance of retail RTE food items with microbiological criteria pertaining to the genus Listeria. Based on the conducted analyses, L. monocytogenes was conclusively determined to be present in one sample. The presence of Listeria spp. was detected in 30.9% of the samples, specifically in Turkish cig kofte, sliced salami, and salads.

Electrochemical DNA Sensor Designed Using the Pencil Graphite Electrode to Detect Listeria monocytogenes.

In the present work, a novel electrochemical DNA sensor was designed to detect L. monocytogenes. Two different gene fragments were selected for the sensor design. One is a 702 bp long fragment of the hlyA gene, encoding the synthesis of listeriolysin O toxin, which is unique only to pathogenic strains of L. monocytogenes and is essential for pathogenicity. The other is a 209 bp long fragment of the 16 S RNA gene found in all species of the Listeria genus. As the working electrode, the pencil graphite electrode was modified in various ways (activated or covered with polypyrrole), and six different combinations were constituted using three types of the modified working electrode and two different gene fragments. The developed system is based on differential pulse voltammetric transduction of guanine oxidation after hybridization between the selected gene fragment (38 µg/mL) and the selected fragment-specific inosine-modified probe (1.8 µmol/L) immobilized on a pencil graphite electrode surface. The comparison of all combinations demonstrates that the best results are obtained with the combination formed from a polypyrrole-coated pencil graphite electrode (prepared at 2 scans) and 702 bp fragment of the hlyA gene. The analysis time is less than 1 hour, and the necessary DNA concentrations for the analysis have been determined as 8.2 × 10-11 M DNA and 2.7 × 10-10 M DNA respectively, for the hlyA gene and 16 S RNA gene.

Cytotoxic, Antioxidant, Antibiofilm, and Antimicrobial Activities of Mushroom Species from Turkey.

Mushrooms, which have been collected to meet the nutritional needs of the world for many years, have gained medical importance thanks to the bioactive compounds they produce. Thanks to studies carried out to determine mushroom diversity, the number of species identified is increasing year by year. Accordingly, in recent years, studies conducted to determine the biological activities of metabolites produced by fungi have been increasing. The present study was conducted to determine the cytotoxic, antioxidant, antibiofilm and antimicrobial activities of the seven different mushroom species (Craterellus cornucopioides, Hymenopellis radicata, Lepista nuda, Pisolithus arhizus, Ramaria flava, Schizophyllum commune, and Tricholoma ustale) collected from Tokat and Yozgat regions located in northern and central Turkey. Laboratory studies have demonstrated that mushrooms used in this study have different degrees of antibiofilm, antimicrobial, antioxidant and cytotoxic activities. At the end of the study, it is determined that C. cornucopioides and L. nuda species have the highest antimicrobial activity. In addition, mushroom species have biofilm inhibitory effects on indicator microorganisms at varying degrees ranging between 20.7 and 96.3%. As a result of antioxidant activity studies, it was determined that T. ustale has the highest free radical scavenging effect and P. arhizus, which has the highest polyphenol content, has the highest reducing power. Finally, it is determined that, among the mushrooms used in the present study, H. radicata showed higher selectivity on the MDA-MB-231 breast cancer cell line than on the normal cell line tested, while C. cornucopioides showed higher selectivity on the MCF-7 breast cancer cell line.

Plant-inspired adhesive and injectable natural hydrogels: in vitro and in vivo studies.

The development of alternative therapeutic treatments based on the use of medicinal and aromatic plants, such as Juniper communis L., has aroused interest in the medical field to find new alternatives to conventional therapeutic treatments, which have shown problems related to bacterial resistance, high costs, or sustainability in their production. The present work describes the use of hydrogels based on sodium alginate and carboxymethyl cellulose, with combinations of juniperus leaves and berry extracts, in order to characterize their chemical characteristics, antibacterial activity, tissue adhesion test, cytotoxicity in the L929 cell line, and their effects on an in vivo model in mice to maximize the use of these materials in the healthcare field. Overall, an adequate antibacterial potential against S. aureus, E. coli and P. vulgaris was obtained with doses above 100 mg.mL-1 of hydrogels. Likewise, low cytotoxicity in hydrogels combined with extracts has been identified according to the IC50 value at 17.32 µg.mL-1, compared to the higher cytotoxic activity expressed by the use of control hydrogels with a value at 11.05 µg.mL-1. Moreover, in general, the observed adhesion was high to different tissues, showing its adequate capacity to be used in different tissue typologies. Furthermore, the invivo results have not shown erythema, edema, or other complications related to the use of the proposed hydrogels. These results suggest the feasibility of using these hydrogels in biomedical applications given the observed safety.

Effect of resistant starch types as a prebiotic.

Since the role of intestinal microbiota in metabolism was understood, the importance of dietary components such as fibres and prebiotics, which affect the modulation of microbiota, has been increasing day by day. While all prebiotic components are considered dietary fibre, not every dietary fibre is considered a prebiotic. While fructooligosaccharides, galactooligosaccharides, inulin, and galactans are considered prebiotics, other fermentable carbohydrates are considered candidate prebiotic components based on in vitro and preclinical studies. Resistant starch, one of such carbohydrates, is considered a potential prebiotic component when it is made resistant to digestion naturally or chemically. In this review, both in vitro and in vivo studies in which the prebiotic capacity of type II, type III, and type IV resistant starch isolated from food and produced commercially was assessed were analyzed. According to the results of current studies, certain types of resistant starch are thought to have a high prebiotic capacity, and they may be candidate prebiotic components although positive results have not been achieved in all studies. KEY POINTS: • Resistant starch is undigested in the small intestine and is fermented in the large intestine. • Resistant starch fermentation positively affects the growth of Bifidobacterium and Lactobacillus. • Resistant starch can be considered a prebiotic ingredient.

Evaluation of metabolic activities and probiotic characteristics of two Latilactobacillus sakei strains isolated from pastirma.

The current study was carried out to investigate metabolic activities and main probiotic characteristics of two Latilactobacillus sakei strains (8.P1 and 28.P2) isolated from pastirma, a highly seasoned, air-dried cured beef. Both strains showed antimicrobial activity against important foodborne pathogens like Listeria monocytogenes, Staphylococcus aureus, Pseudomonas aeruginosa and so forth. For the characterization of antimicrobial activity, the effect of various enzymes, temperature and pH were tested. The results of the tests demonstrated that the antimicrobial activity of strains was based on the production of protein-structured compounds such as bacteriocin or bacteriocin like peptides. In metabolic activity studies, amounts of the lactic acid, proteolytic activity and hydrogen peroxide produced by the 8.P1 and 28.P2 were found to range between 16.09 and 17.32 mg/mL, 0.24 and 0.04 mg/mL and 0.98 and 0.04 µg/mL, respectively. It was also observed that neither strain could produce exopolysaccharide. Both strains were found susceptible to vancomycin, chloramphenicol, gentamicin, tetracycline, and netilmicin sulfate. When the strains are evaluated with respect to their probiotic potential, 28.P2 could tolerate acidic conditions, but 8.P1 showed sensitivity. The survival rate of the strains in the simulated gastric juice and their adhesion abilities were found suitable to stay alive in the gastrointestinal tract and to proliferate in the intestine. The evaluation of all the features of both strains demonstrated that both strains had the potential to be used as a protective culture. In addition, it was observed that 8.P1 and 28.P2 were more suitable as a starter culture and a probiotic candidate respectively.

In vitro evaluation of probiotic potential of Enterococcus faecium strains isolated from Turkish pastirma.

This study is aimed at evaluating the probiotic potential of three Enterococcus faecium strains (called 29-P2, 168-P6 and 277-S3) isolated from 'pastirma', a Turkish traditional dry-cured meat product. For this, key probiotic properties and some functional characteristics of strains were tested in vitro. Antimicrobial activity of 3 E. faecium strains was evaluated against 18 indicator microorganisms consisting of 13 foodborne pathogens and 5 lactic acid bacteria and all strains were found as the producer of antimicrobial substance. Especially one strain 168-P6 showed a remarkable activity spectrum and inhibited all of the used foodborne pathogen indicators. Antimicrobial compounds produced by strains were identified by determining the effect of enzyme, pH and temperature on antimicrobial activity. All strains exhibited tolerance to acidic conditions and a simulated gastric environment. Also, strains exhibited high adhesion capacity. The safety of the strains was assessed by determining hemolytic activity and the resistance to 14 different antibiotics. None of the three strains exhibited hemolytic activity, also strains were found reliable in terms of clinically relevant antibiotics, only one strain 29-P2 was found resistant to vancomycin. In addition, metabolic activities of strains including lactic acid, hydrogen peroxide, exopolysaccharide production and proteolytic activity were determined and amounts of all metabolic products were found low. When evaluated all data obtained, it is believed that the strains have enviable characteristics as a probiotic candidate.

Postoperative Analgesic Efficacy of Preemptive and Postoperative Lornoxicam or Tramadol in Lumbar Disc Surgery.

OBJECTIVE: To compare preemptive and postoperative analgesic efficacy of tramadol and lornoxicam administered before anaesthesia induction in lumbar discectomy. METHODS: This randomised, double-blind trial was conducted on 60 ASA I and II patients undergoing lumbar discectomy. Group L (n=30) received 3×8 mg day-1 lornoxicam, and Group T (n=30) received 3×1.5 mg kg-1 day-1 tramadol. A verbal rating scale (VRS), the duration of effective analgesia, the number of additional analgesics used, adverse effects and patient satisfaction were evaluated at the postoperative 30th minute and 1st, 2nd, 4th, 6th, 8th, 12th and 24th hours. RESULTS: There were no significant differences between Groups L and T regarding demographic and clinical characteristics, the number of additional analgesics and the duration of effective analgesia, adverse effects and patient satisfaction. VRS scores of the patients in Group T were significantly higher than those in Group L at the postoperative 30th minute (p=0.050) and the 1st hour (p=0.005). CONCLUSION: Lornoxicam, which was used for preemptive and postoperative analgesia in lumbar disc surgery, had provided adequate and effective analgesia such as tramadol. Moreover, preemptive analgesia was quite effective in prevention and treatment of postoperative pain.

Alterations in bacterial spectrum and increasing resistance rates in isolated microorganisms from device-associated infections in an intensive care unit of a teaching hospital in Istanbul (2004-2010).

The aim of the present study was to determine the rate of device-associated infection (DAI) and the change in profiles and antimicrobial resistance patterns of the causative microorganisms in a medical-surgical intensive care unit (ICU), as well as to evaluate the effect of a new nationwide hospital infection control program (NHICP), which has been implemented in Turkey. In this study, 5,772 patients that were hospitalized for a total of 43,658 days acquired 1,321 DAIs, with an overall rate of 30.2% per 1,000 ICU days. Between 2004 (before the NHICP) and 2010, the incidence densities of catheter-associated urinary tract infection (CAUTI) decreased from 10.2 to 5.7 per 1,000 device-days (P < 0.0001), and central venous catheter-associated bloodstream infection (CVC-BSI) decreased from 5.3 to 2.1 per 1,000 device-days (P < 0.0001). However, ventilator-associated pneumonia increased from 27.0 to 31.5 per 1,000 device-days. Multidrug-resistant species rates increased from 5.8% to 76.6% (P < 0.0001) for Acinetobacter spp. and from 6.8% to 53.1% (P < 0.0001) for Pseudomonas aeruginosa. The extended-spectrum ß-lactamase-producing Enterobacteriaceae rate increased from 23.1% to 54.2% (P = 0.01); the vancomycin-resistance rate among Enterococcus spp. increased from 0% in 2004 to 12.5% in 2010 (P = 0.0003). In conclusion, while a significant decrease was achieved in the incidences of CAUTI and CVC-BSI, the NHICP was not completely effective in our ICU. The high incidence of DAI and the increasing prevalence of multidrug-resistant microorganisms indicate that further interventions are urgently needed.

Incidence, etiology, and antibiotic resistance patterns of gram-negative microorganisms isolated from patients with ventilator-associated pneumonia in a medical-surgical intensive care unit of a teaching hospital in istanbul, Turkey (2004-2006).

The identification of microorganisms causing ventilator-associated pneumonia (VAP) is important for formulating appropriate therapies. In this study, we report the incidence, etiology, and antibiotic resistance patterns of Gram-negative microorganisms isolated from patients diagnosed with VAP in our medical-surgical intensive care unit (ICU) during the years 2004-2006. VAP was diagnosed by using the clinical criteria of the Centers for Disease Control and Prevention. Antibiotic resistance patterns of isolated microorganisms were defined by standard methods. The VAP incidence rate was 22.6/1,000 ventilator days. The most frequently isolated pathogens were Acinetobacter spp., methicillin-resistant Staphylococcus aureus, and Pseudomonas aeruginosa. Ninety percent of Acinetobacter spp. isolates were resistant to ceftazidime, 64% to imipenem, and 80% to ciprofloxacin. Fifty-nine percent of P. aeruginosa isolates were resistant to ceftazidime, 32% to imipenem, and 62% to ciprofloxacin. Cefoperazone-sulbactam was the most active agent against Acinetobacter spp. In conclusion, the incidence of VAP and the prevalence of multidrug-resistant microorganisms are quite high in our ICU. Comparison of the resistance rates of isolates demonstrates that certain antibiotic agents are more effective than others.