Characteristics of Listeria monocytogenes Strains Isolated from Milk and Humans and the Possibility of Milk-Borne Strains Transmission.

Listeria monocytogenes is the etiological factor of listeriosis. The main source of these organisms is food, including dairy products. The aim was to determine the multiple correlations between the drug susceptibility, virulence genes (VGs), and biofilm formation on silicone teat cups of milk-borne and human L. monocytogenes strains. The spread of L. monocytogenes via contaminated teat rubbers was assessed. The L. monocytogenes strains recovered from milk (18), human blood (10), and the reference strain ATCC®19111™ were used in the study. Penicillin resistance was the most prevalent resistance in the milk isolates (n=8; 44.4%), whereas among clinical strains erythromycin resistance was predominating - (n=6; 60%). The most frequent VGs among strains isolated from milk were hlyA (100%) and plcB (100%) whereas in strains isolated from blood - hlyA (100%) and prfA (90%). All tested VGs were present in 50% of blood isolates and 11% of milk-borne strains. The strains isolated from milk formed a significantly stronger biofilm. The strains with more numerous virulence genes were resistant to more antibiotics and formed a stronger biofilm. It was shown that contaminated teat cups might contribute to the transmission of L. monocytogenes in the herd. It seems reasonable to monitor the occurrence of L. monocytogenes biofilm in a dairy processing environment.Listeria monocytogenes is the etiological factor of listeriosis. The main source of these organisms is food, including dairy products. The aim was to determine the multiple correlations between the drug susceptibility, virulence genes (VGs), and biofilm formation on silicone teat cups of milk-borne and human L. monocytogenes strains. The spread of L. monocytogenes via contaminated teat rubbers was assessed. The L. monocytogenes strains recovered from milk (18), human blood (10), and the reference strain ATCC®19111™ were used in the study. Penicillin resistance was the most prevalent resistance in the milk isolates (n=8; 44.4%), whereas among clinical strains erythromycin resistance was predominating ­ (n=6; 60%). The most frequent VGs among strains isolated from milk were hlyA (100%) and plcB (100%) whereas in strains isolated from blood ­ hlyA (100%) and prfA (90%). All tested VGs were present in 50% of blood isolates and 11% of milk-borne strains. The strains isolated from milk formed a significantly stronger biofilm. The strains with more numerous virulence genes were resistant to more antibiotics and formed a stronger biofilm. It was shown that contaminated teat cups might contribute to the transmission of L. monocytogenes in the herd. It seems reasonable to monitor the occurrence of L. monocytogenes biofilm in a dairy processing environment.

Disinfectant Susceptibility of Biofilm Formed by Listeria monocytogenes under Selected Environmental Conditions.

Listeria monocytogenes is a one of the most important food-borne pathogens. Its ability to form biofilm contributes to increased resistance to disinfectants and inefficient disinfection, posing a serious threat for the food industry, and in the end the consumer. The aim of this study was the comparison of the biofilm formation ability of L. monocytogenes strains on stainless steel, under different environmental conditions (temperature, pH, NaCl concentration, nutrients availability), and the assessment of biofilm susceptibility to disinfectants. The bactericidal activity of four disinfectants in two concentrations (100% and 50% of working solution) against biofilm was conducted on four clinical strains, four strains isolated from food and one reference strain ATCC 19111. It was found that biofilm susceptibility to disinfectants was influenced by environmental conditions. Biofilm susceptibility correlated with the decrease of temperature, pH, nutrients availability and salinity of the environment. The least sensitive to disinfectants was biofilm produced at pH = 4 (the bacterial number ranged from 0.25 log CFU × cm-2 to 1.72 log CFU × cm-2) whereas the most sensitive was biofilm produced at pH = 9 (5.16 log CFU × cm-2 to 7.84 log CFU × cm-2). Quatosept was the most effective disinfectant, regardless of the conditions. In conclusion, biofilm susceptibility to disinfectants is strain-dependent and is affected by environmental conditions.

Biocidal Effectiveness of Selected Disinfectants Solutions Based on Water and Ozonated Water against Listeria monocytogenes Strains.

The aim of this study was to compare the biocidal effectiveness of disinfectants solutions prepared with ozonated and non-ozonated water against Listeria monocytogenes. Six L. monocytogenes strains were the research material (four isolates from food: meat (LMO-M), dairy products (LMO-N), vegetables (LMO-W), and fish (LMO-R); one clinical strain (LMO-K) and reference strain ATCC 19111). The evaluation of the biocidal effectiveness of disinfectant solutions (QAC-quaternary ammonium compounds; OA-oxidizing agents; ChC-chlorine compounds; IC-iodine compounds; NANO-nanoparticles) was carried out, marking the MBC values. Based on the obtained results, the effectiveness coefficient (A) were calculated. The smaller the A value, the greater the efficiency of disinfection solutions prepared on the basis of ozonated versus non-ozonated water. Ozonated water showed biocidal efficacy against L. monocytogenes. Among tested disinfectentants, independent on type of water used for preparation, the most effective against L. monocytogenes were: QAC 1 (benzyl-C12-18-alkydimethyl ammonium chlorides) (1.00 × 10-5-1.00 × 10-4 g/mL) in quaternary ammonium compounds, OA 3 (peracetic acid, hydrogen peroxide, bis (sulphate) bis (peroxymonosulfate)) (3.08 × 10-4 -3.70 × 10-3 g/mL) in oxidizing agents, ChC 1 (chlorine dioxide) (5.00 × 10-8 -7.00 × 10-7 g/mL) in chlorine compounds, IC 1 (iodine) (1.05-2.15 g/mL) in iodine compounds, and NANO 1 (nanocopper) (1.08 × 10-4 - 1.47 × 10-4 g/mL) in nanoparticles. The values of the activity coefficient for QAC ranged from 0.10 to 0.40, for OA-0.15-0.84, for ChC-0.25-0.83, for IC-0.45-0.60, and for NANO-0.70-0.84. The preparation of disinfectants solution on the basis of ozonated water, improved the microbicidal efficiency of the tested disinfectant, especially the quaternary ammonium compounds. An innovative element of our work is the use of ozonated water for the preparation of working solutions of the disinfection agents. Use ozonated water can help to reduce the use of disinfectant concentrations and limit the increasing of microbial resistance to disinfectants. This paper provides many new information to optimize hygiene plans in food processing plants and limit the spread of microorganisms such as L. monocytogenes.

Antilisterial Activity of Polypropylene Film Coated with Chitosan with Propolis and/or Bee Pollen in Food Models.

The aim of the study was to evaluate the effect of propylene film coated with solution of chitosan (CH), ethanolic extracts of propolis (EEP), and bee pollen (EEBP) and its combination on L. monocytogenes number in wrapped salmon, salami, and cheese. Sterile fragments of propylene film were coated with solution containing CH, CH+EEP, CH+EEBP, and CH+EEP+EEBP. The coated film was applied directly after preparation (AP) after 10 days of storage from preparation (AS). L. monocytogenes strains isolated from cheese, salmon, and salami were transferred on adequate food type. ATCC 19111 reference strain was placed on all examined slices. Contaminated slices were wrapped in the coated film. The film adhered strictly to the slices surface and was left for 0, 1, 6, 12, and 24 hours. Antilisterial activity of AP film was additionally assessed during 15-day storage of products wrapped in the coated film. In conclusion, the chitosan-coated film exhibited antibacterial activity. Incorporation of EPP and EEBP enhanced this activity. The antilisterial activity depended on the type and concentration of solutions, the types of food, and the origin of strains. This study proved that the time that passed since the use of coated film for packing food was of great importance.

Drug-susceptibility, biofilm-forming ability and biofilm survival on stainless steel of Listeria spp. strains isolated from cheese.

The aim of the study was to analyze the contamination of mold cheese (Brie, Camembert, Gorgonzola, Munster and Roquefort) with Listeria spp. and assessment of culturable cells number recovered from the biofilm formed on the surface of stainless steel by obtained strains. Identified isolates (MALDI TOF MS technique) were subjected to susceptibility testing (disk-diffusion method) and their genetic similarity (PFGE method), ability to form biofilm (quantitative method), biofilm dry weight, and biofilm survival on stainless steel were evaluated. Out of 250 samples of cheese 26 (10.4%) were Listeria spp. positive, including 15 isolates (6.0% of samples) of L. monocytogenes, 7 isolates of L. innocua (2.8% of samples) and 4 isolates of L. welshimeri species (1.6% of samples). Of the 26 isolates tested, 22 strains were genetically different. It was shown that L. innocua and L. welshimeri strains were sensitive to all antibiotics tested, while two (16.7%) L. monocytogenes strains were resistant to penicillin and one (8.3%) to erythromycin. L. monocytogenes formed biofilm most intensively on stainless steel, while L. welshimeri the least effectively. The median of bacteria number recovered from the biofilm for L. monocytogenes was 6.81 log CFU × cm-2, for L. innocua - 5.63 log CFU × cm-2, and for L. welshimeri - 4.93 log CFU × cm-2. The survival in the biofilm of Listeria spp. strains decreased along with the increase in a storage temperature of steel coupons. The longest survival time was reported at 4 °C, i.e. 47.58-124.41 days, with an elimination rate of 0.06-0.13 log CFU × day-1. Collectively, L. monocytogenes is the most prevalent species of Listeria genus in the mold cheese. The ability of L. monocytogenes strains to form biofilm on stainless steel and survive in the food processing environment increases chance of the secondary contamination of food posing risk to the consumer health.

Comparison of the effectiveness of dipping agents on bacteria causing mastitis in cattle.

INTRODUCTION: Mastitis may result in physical, chemical and microbiological changes in milk and pathological lesions in the glandular tissue. Milk derived from cows with mastitis may become a cause of infections in humansw and animals. OBJECTIVES: The aim of this study was to assess the effectiveness of selected dipping agents in the inactivation of several bacteria that may cause mastitis in cattle. MATERIAL AND METHODS: Three strains of each of the following species: Escherichia coli, Klebsiella pneumoniae, Serratia marcescens, Staphylococcus aureus and Listeria monocytogenes, isolated from milk, were used in the study. Identification of isolates was carried out using the automatic system VITEK2 Compact. Evaluation of the genetic similarity between the tested strains was made using the RAPD technique. Drug susceptibility of strains was evaluated with the disc diffusion method. Assessment of the effectiveness of iodine, stabilized iodine, povidone iodine and chlorhexidine was performed using fragments of skin from cow teats. RESULTS: All the tested strains were genetically different. Most of them were susceptible to the studied antibiotics. Only two strains of L. monocytogenes were resistant to all the studied antibiotics. The percentage rate of reduction in the number of bacteria after using of dipping agents was very high (>90%). The most susceptible to the dipping preparations used were L. monocytogenes (99.6 - 99.9%). Stabilized iodine was the most effective dipping agent for all tested bacteria, causing a reduction rate in the number of bacteria from 99.80% (E. coli) - 99.99% (S. aureus, L. monocytogenes). CONCLUSIONS: The results obtained may contribute to a reduction in udder infections in cows, especially mastitis, and improve the quality of the milk.

Effect of Selected Environmental Factors on the Microbicidal Effectiveness of Radiant Catalytic Ionization.

The aim of this study was the assessment of the effect of time exposure, temperature, distance, and organic contaminants on radiant catalytic ionization (RCI) microbicidal effectiveness. The number of all examined bacteria decreased together with time exposure of RCI. The lowest recovery was obtained, both from the rubber surface (6.36 log CFU × cm-2) and steel (6.04 log CFU × cm-2) in the case of Escherichia coli O157:H7. On the other hand, Staphylococcus aureus was isolated in the largest number (rubber: 7.88 log CFU × cm-2, steel: 7.79 log CFU × cm-2). Among the tested environmental conditions, the greatest bacterial population was re-isolated at 4°C (distance: 0.5 m, time: 24 h), whereas the lowest population was found at a distance of 0.5 m (temperature: 20°C, time: 24 h) and on surfaces without contamination. In the samples treated with RCI, the bacterial population was the lowest on non-contaminated surfaces, ranging from 3.76 log CFU × cm-2 (E. coli O157:H7) to 5.58 log CFU × cm-2 (S. aureus) for the rubber, and from 3.26 log CFU × cm-2 (E. coli O157:H7) to 5.20 log CFU × cm-2 (S. aureus) for the stainless steel. The highest bacteria number was isolated from surfaces contaminated with meat and fish pulp. The lowest bacterial reduction caused by RCI was found in the case of rubber contaminated with meat-fish pulp (24 h, 0.5 m, 20°C). The reduction rate was equal to 0.89 log CFU × cm-2 for S. aureus, 1.17 log CFU × cm-2 for Listeria monocytogenes, 1.43 log CFU × cm-2 for Salmonella Enteritidis and 1.61 log CFU × cm-2 for E. coli O157:H7. In turn, the greatest bacterial reduction was found in the case of non-contaminated steel (24 h, 0.5 m, 37°C). The reduction rate was equal to 4.52 log CFU × cm-2 for L. monocytogenes, 3.61 log CFU × cm-2 for S. Enteritidis, 2.98 log CFU × cm-2 for E. coli O157:H7 and 2.77 log CFU × cm-2 for S. aureus. RCI allows the inactivation of pathogens from stainless steel and rubber surfaces. Its efficacy is species-dependent and affected by environmental factors.

The occurrence, transmission, virulence and antibiotic resistance of Listeria monocytogenes in fish processing plant.

The aim of this research was to investigate the occurrence of Listeria monocytogenes in fish and fish processing plant and to determine their transmission, virulence and antibiotic resistance. L. monocytogenes was isolated according to the ISO 11290-1. The identification of L. monocytogenes was confirmed by multiplex PCR method. Genetic similarity of L. monocytogenes strains was determined with the Pulsed-Filed Gene Electrophoresis (PFGE) method. The multiplex PCR was used for identification of L. monocytogenes serogroups and detection of selected virulence genes (actA, fbpA, hlyA, iap, inlA, inlB, mpl, plcA, plcB, prfA). The L. monocytogens isolates susceptibility to penicillin, ampicillin, meropenem, erythromycin, trimethoprim/sulfamethoxazole was evaluated with disc diffusion method according to EUCAST v. 7.1. The presence of 237 L. monocytogenes isolates (before genetic similarity assessment) in 614 examined samples was confirmed. After strain differentiation by PFGE techniques the presence of 161 genetically different strains were confirmed. The genetic similarity of the examined isolates suggested that the source of the L. monocytogenes strains were fishes originating from farms. All tested strains possessed all detected virulence genes. Among examined strains, the most (26, 38.6%) belonged to the group 1/2a-3a. The most of tested strains were resistant to erythromycin (47.1%) and trimethoprim/sulfamethoxazole (47.1%).

Efficacy of radiant catalytic ionization to reduce bacterial populations in air and on different surfaces.

Air contamination by biological agents is often observed in medical or veterinary facilities and industrial plants. Bioaerosols may sediment and pose the surface contamination. Microorganisms present on them may become a source of infections among humans and food contamination. This study determined the use of oxidative gases, including ozone and peroxide, generated by the Radiant Catalytic Ionization (RCI) cell for the inactivation of Acinetobacter baumannii, Escherichia coli, Enterococcus faecalis, Pseudomonas aeruginosa, Salmonella Enteritidis, Listeria monocytogenes, Staphylococcus aureus, Streptococcus epidermidis, Bacillus subtilis, Clostridium sporogenes, Candida albicans, Aspergillus niger and Penicillium chrysogenumon in air and on different surfaces. Results showed that oxidative gases produced by the RCI cell reduced all tested microorganisms. The full elimination of studied microorganisms from the air was obtained for E. coli and C. albicans. RCI also proved to be an effective method of eliminating microbes from the examined surfaces. Regarding of the species, strains origin and the type of surface, the reduction rate ranged from 19.0% for C. albicans to over 99% for A. baumanii. For both, air and surface, the most resistant to RCI was C. sporogenes spores, for which the percentage reduction rate ranged from -2.6% to 71.2% on the surfaces and was equal 71.7% in the air.

Microbiological purity assessment of cosmetics used by one and several persons and cosmetics after their expiry date

Background: Microbiological purity of cosmetics provides safety of users during their use, prevents physicochemical changes of a preparation, infections and diseases of the skin. Objective: The aim of this study was to assess the level of microbiological contamination of cosmetics used by one person and by several people and cosmetics after their expiry date in relations to standards for marketed cosmetics, ensuring safety of their use. Material and Methods: This study was conducted using 55 samples representing 19 types of cosmetics, divided into three groups: used by one person, used by several people and after the expiry date. In cosmetic samples the general numbers of aerobic mesophilic bacteria were determined with the spread plate method on tryptic-soy agar. The presence of Staphylococcus aureus, Pseudomonas aeruginosa and Candida albicans were also checked. Results: The number of aerobic mesophylic bacteria in the tested cosmetics ranged from the level below the method detectability to 1.3×107 cfu/g or ml. The presence of Staphylococcus spp. was found in 11 (20.0%) tested cosmetic samples and of P. aeruginosa in one tested preparation. Yeasts C. albicans were not detected, whereas contamination with fungi Aspergillus spp. and Penicillium spp. ranging from 0.5×101 to 1.5×101 cfu/g or ml was recorded in four cosmetics. The level of microbiological contamination of cosmetics used by several people was higher than that of cosmetics used by one person. Cosmetics after the expiry date showed the highest microbiological contamination. Conclusions: The number of users of cosmetic and it expiry date exceeding influenced the level of microbial contamination of preparations.

Fecal microbiota transplantation - methods of treatment of recurrent Clostridium difficile infections and other diseases.

Clostridium difficile is a serious epidemiological problem and particularly dangerous microorganism causing hospital infections. Currently, the treatment of C. difficile infections is the use of metronidazole or vancomycin. However, in some patients, recurrent infection difficult to treat occurs. Fecal microbiota transplantation (FMT) is a new method used to treat the recurrent CDI. FMT consists in the infusion of the fecal suspension from a healthy donor into the gastrointestinal tract of a patient with CDI to restore the natural intestinal microflora. FMT is safe and effective treatment of recurrent CDI. FMT is extensively described around the world, but to date only two randomized studies confirming the effectiveness of FMT have been conducted. This method was also applied in the treatment of diseases such as pseudomembranous colitis, ulcerative colitis, Crohn's disease and irritable bowel syndrome. The review describes the procedure for FMT and the current state of knowledge about the effectiveness of FMT in the treatment of recurrent CDI.

Virulence genes and antimicrobial susceptibility of lactose-negative and lactose-positive strains of Escherichia coli isolated from pregnant women and neonates.

Escherichia coli can cause serious infections in the neonates and pregnant women. Although E. coli is widely studied, E. coli lactose-negative (lac-) strains have been rarely described before. So, the aim of this study was to compare lac- and lactose-positive (lac+) E. coli strains in respect of antimicrobial susceptibility and the frequency of virulence genes (VGs). The study included 58 lac+ and 58 lac- E. coli strains isolated from pregnant women and neonates. Culture and the results of biochemical reactions were conducted for lac- and lac+ E. coli identification and differentiation. Disc diffusion test was performed to study the antimicrobial susceptibility of the isolates, and PCR was used to detect VGs. Resistance to at least one of the tested antibiotics was found among 14 (25.9%) E. coli lac+ and in 26 (44.9%) E. coli lac- strains. Both lac+ and lac- E. coli strains were mostly resistant to ampicillin (22.4 and 39.7%) and ticarcillin (20.7 and 39.7%). None of the tested strains produced extended-spectrum ß-lactamases (ESBLs). Genes fimH, fimA, iutA, sfa/foc, neuC, ibeA, and hlyF were detected, respectively, in 96.6, 82.8, 32.8, 24.1, 22.4, 12.1, and 6.9% of lac+ E. coli strains and in 94.8, 86.2, 48.3, 19.0, 8.6, 8.6, and 1.7% of lac- strains. The antimicrobial susceptibility and the pathogenic potential of both tested groups of E. coli strains are similar. Therefore, omitting E. coli lac- strains as a potential etiological agent of infections may pose a threat to the health and life of both mothers and neonates.