Hercules Sakkas

Antimicrobial Resistance of Major Foodborne Pathogens from Major Meat Products

The bacterial contamination of raw and processed meat products with resistant pathogens was studied. The raw samples included sheep (40), goat (40), pork (120), beef (80), and chicken (19) meat, and the processed samples included turkey filets (33), salami (8), readymade mincemeat (16), stuffing (22), and roast-beef (50). The samples were collected from retail shops in Northwestern Greece over a period of 3 years. The isolated pathogens were evaluated for susceptibilities to 19 antimicrobial agents used in humans. Out of 428 samples, 157 strains of Escherichia coli, 25 of Yersinia enterocolitica, 57 of Staphylococcus aureus, 57 of Enterococcus spp., 4 of Salmonella spp., and 3 of Campylobacter jejuni were isolated. Among the isolates 14.6% of the E. coli, 10.5% of S. aureus, 4% of Y. enterocolitica, 25% of Salmonella spp., and 42.1% of Enterococcus spp. were susceptible to antibiotics. E. coli from chicken exhibited high rates of resistance to ciprofloxacin (62.5%) followed by lamb/goat (10.9%), pork (15.7%), and beef (27.9%) meat. Resistance to nitrofurantoin dominated in the lamb/goat isolates (60%). Resistance to tetracycline predominated in pork (68.2%) and chicken (62.5%), and resistance to aminoglycosides dominated in lamb/goat meat isolates. S. aureus resistance to clindamycin predominated in lamb/goat isolates (50%), whereas resistance to ciprofloxacin predominated in the pork strains, but no resistance to methicillin was observed. Of the enterococci isolates 21.1% were resistant to vancomycin. High resistance to ampicillin (96%) was observed in Y. enterocolitica and all of the C. jejuni isolates were resistant to ampicillin, cephalothin, and cefuroxime. These results indicate that meat can be a source of resistant bacteria, which could potentially be spread to the community through the food chain.

Prevalence, antimicrobial resistance and relation to indicator and pathogenic microorganisms of Salmonella enterica isolated from surface waters within an agricultural landscape.

During a 12 month period (June 2007-May 2008), the prevalence and susceptibility of Salmonella serovars and their relation to specific pathogenic and indicator bacteria in river and coastal waters was investigated. A total of 240 water samples were collected from selected sites in Acheron and Kalamas Rivers and the Ionian Sea coast in north western Greece. The samples were analyzed for Salmonella spp., Listeria spp., Campylobacter spp., Escherichia coli O157, Staphylococci, Pseudomonas spp., Total Coliforms, Fecal Coliforms, Fecal Streptococci, Total Heterotrophic Flora at 20°C and at 37°C, fungi and protozoa (Cryptosporidium, Giardia). Susceptibility tests to nine antimicrobials (ampicillin, amikacin, amoxicillin/clavulavic acid, cefuroxime, ciprofloxacin, cefoxitin, tetracycline, ticarcillin/clavulanic acid, ampicillin/sulbactam) were performed using the disk diffusion method for Salmonella isolates. We isolated 28 serovars of Salmonella spp. identified as Salmonella enteritidis (23), Salmonella thompson (3) and Salmonella virchow (2). Multi-drug resistant Salmonella serovars were isolated from both river and marine waters, with 34.8% of S. enteritidis and 100% of S. virchow being resistant to more than 3 antibiotics. Also we isolated 42 strains of Listeria spp. identified as L. monocytogenes (20), L. innocua (9), L. seeligeri (2) and L. ivanovii (11). All the Listeria isolates were susceptible to the tested antibiotics. No Campylobacter spp., E. coli O157, Cryptosporidium and Giardia were detected. The overall ranges (and average counts) of the indicator bacteria were: Total Coliforms 0-4×10(4)cfu/100ml (3.7×10(3)cfu/100ml), Fecal Coliforms 0-9×10(3)cfu/100ml (9.2×10(2)cfu/100ml), Fecal Streptococci 0-3.5×10(4)cfu/100ml (1.4×10(3)cfu/100ml), Total Heterotrophic Flora at 20°C 0-6×10(3)cfu/ml (10(3)cfu/ml) and at 37°C 0-5×10(3)cfu/ml (4.9×10(2)cfu/ml). Weak or non significant positive Spearman correlations (p<0.05, rs range: 0.13-0.77) were obtained between Salmonella, Listeria, fungi and indicator bacteria. The results underline the complexity of the interrelations between pathogens and indicator bacteria, and the necessity to assess the presence of resistant bacteria in the aquatic environments.

Chemical investigation and antimicrobial properties of mastic water and its major constituents.

Mastic water is a commercial flavouring obtained during the steam distillation of mastic resin (the resin of Pistacia lentiscus var. chia) for the production of mastic oil. The mastic water extracts were analysed by GC-MS. The major compounds identified were verbenone, α-terpineol, linalool and trans-pinocarveol. Overall the composition was found to be very different from that of mastic oil. Additional GC-MS revealed the enantiomeric ratio of the chiral constituents of mastic water. The antimicrobial activity of mastic water extract, as well as that of its major constituents, was examined against Escherichia coli, Staphylococcus aureus and Candida spp. including ATCC wild clinical and food-borne strains. Linalool and α-terpineol were found to be the most potent antimicrobial constituents. Finally the stability of mastic water at different temperatures was studied, showing no change in the GC-MS profile of the organic extract for a period of 4months at storage temperatures up to 4°C.

Antimicrobial activity of Basil, Oregano and Thyme essential oils.

For centuries, plants have been used for a wide variety of purposes, from treating infectious diseases to food preservation and perfume production. Presently, the increasing resistance of microorganisms to currently used antimicrobials in combination with the appearance of emerging diseases requires the urgent development of new, more effective drugs. Plants, due to the large biological and structural diversity of their components, constitute a unique and renewable source for the discovery of new antibacterial, antifungal, and antiparasitic compounds. In the present paper, the history, composition, and antimicrobial activities of the basil, oregano, and thyme essential oils are reviewed.

In vitro antimicrobial activity of five essential oils on multi-drug resistant Gram-negative clinical isolates -

Aim/Background: The emergence of drug-resistant pathogens has drawn attention on medicinal plants for potential antimicrobial properties. The objective of the present study was the investigation of the antimicrobial activity of five plant essential oils on multidrug resistant Gram-negative bacteria. Materials and Methods: Basil, chamomile blue, origanum, thyme, and tea tree oil were tested against clinical isolates of Acinetobacter baumannii (n = 6), Escherichia coli (n = 4), Klebsiella pneumoniae (n = 7), and Pseudomonas aeruginosa (n = 5) using the broth macrodilution method. Results: The tested essential oils produced variable antibacterial effect, while Chamomile blue oil demonstrated no antibacterial activity. Origanum, Thyme, and Basil oils were ineffective on P. aeruginosa isolates. The minimum inhibitory concentration (MIC) and minimum bactericidal concentration values ranged from 0.12% to 1.50% (v/v) for tea tree oil, 0.25-4% (v/v) for origanum and thyme oil, 0.50% to >4% for basil oil and >4% for chamomile blue oil. Compared to literature data on reference strains, the reported MIC values were different by 2SD, denoting less successful antimicrobial activity against multidrug resistant isolates. Conclusions: The antimicrobial activities of the essential oils are influenced by the strain origin (wild, reference, drug sensitive, or resistant) and it should be taken into consideration whenever investigating the plants’ potential for developing new antimicrobials.

Conventional and molecular methods used in the detection and subtyping of Yersinia enterocolitica in food

Yersinia enterocolitica is an important foodborne pathogen, but the prevalence in food is underestimated due to drawbacks in the detection methods. Problems arise from the low concentration of pathogenic strains present in food samples, similarities with other Enterobacteriaceae and Y. enterocolitica-like species and the heterogeneity of Y. enterocolitica as it comprises both pathogenic and non-pathogenic isolates. New rapid, cost-effective and more sensitive culture media and molecular techniques have been developed to overcome the drawbacks of conventional culture methods. Recent molecular subtyping methods have been applied to Y. enterocolitica strains to track infection sources and to investigate phylogenetic relationships between different Yersinia strains. Further application of modern subtyping tools such as WGS in a variety of bioserotypes, and comparison with other members of the genus will help to better understanding of the virulence determinants of pathogenic Y. enterocolitica, its mechanisms to cope in the host environments, and can contribute to the development of more specific detection and typing strategies.

Shelf-life of smoked eel fillets treated with chitosan or thyme oil

The present study examined the effect of natural antimicrobials: Chitosan, thyme oil and their combination, on the shelf-life of smoked eel fillets stored under vacuum packaging (VP) at 4°C. Based on sensory odor data smoked eel fillets had a shelf-life of 35 (control), 42 (thyme treated and>49 (thyme, chitosan-thyme treated) days. The thiobarbituric acid value (TBA) value of the control eel sample was significantly higher than the chitosan-thyme-treated eel samples. The use of chitosan singly, or in combination with thyme oil reduced lipid oxidation (TBA) of the smoked eel samples. A trimethylamine nitrogen (TMA-N) value of 10mgN/100g, could be suggested as an indication of smoked eel spoilage initiation. Control and treated eel reached total volatile basic nitrogen (TVB-N) values of 13.1-31.5mgN/100g below the maximum permissible level of TVB-N in fish and fishery products. Eel samples reached the value of 7.0logcfu/g (Total Plate Count, TPC) on days 35 (smoked) and 42 (thyme treated), whereas both chitosan and chitosan-thyme treated eel samples never reached this limit value. Results of our study show thyme or chitosan (singly, or in combination) inhibit the growth of mesophilic bacteria and extend the shelf-life of smoked eel.

Oropouche Fever: A Review

Oropouche fever is an emerging zoonotic disease caused by Oropouche virus (OROV), an arthropod transmitted Orthobunyavirus circulating in South and Central America. During the last 60 years, more than 30 epidemics and over half a million clinical cases attributed to OROV infection have been reported in Brazil, Peru, Panama, Trinidad and Tobago. OROV fever is considered the second most frequent arboviral febrile disease in Brazil after dengue fever. OROV is transmitted through both urban and sylvatic transmission cycles, with the primary vector in the urban cycle being the anthropophilic biting midge Culicoides paraensis. Currently, there is no evidence of direct human-to-human OROV transmission. OROV fever is usually either undiagnosed due to its mild, self-limited manifestations or misdiagnosed because its clinical characteristics are similar to dengue, chikungunya, Zika and yellow fever, including malaria as well. At present, there is no specific antiviral treatment, and in the absence of a vaccine for effective prophylaxis of human populations in endemic areas, the disease prevention relies solely on vector control strategies and personal protection measures. OROV fever is considered to have the potential to spread across the American continent and under favorable climatic conditions may expand its geographic distribution to other continents. In view of OROV’s emergence, increased interest for formerly neglected tropical diseases and within the One Health concept, the existing knowledge and gaps of knowledge on OROV fever are reviewed.

Antimicrobial photodynamic therapy using Indocyanine green and near-infrared diode laser in reducing Entrerococcus faecalis

BACKGROUND The use of Antimicrobial Photodynamic Therapy (aPDT) has been suggested as an adjuvant method to eliminate facultative bacteria during root canal disinfection. The purpose of this preliminary in vitro study was to determine whether the light-activated antimicrobial agent, Indocyanine green (ICG), could be used as photosensitizer and kill Enterococcus faecalis strain under planktonic conditions when irradiated with near-infared (NIR) diode laser emitting in 810nm wavelength. METHODS Planktonic suspension containing Enterococcus faecalis strain was divided into nine experimental groups: (1) aPDT with ICG and laser (medium energy fluence), (2) aPDT with ICG and laser (high energy fluence), (3) only ICG without laser activation, (4) only laser emission without ICG (5) 2.5% Sodium hypochlorite (NaOCl) as irrigant, (6) 2.5% NaOCl and aPDT with ICG and laser, (7) 2.0% Chlorhexidine gluconate (CHX) as irrigant (8) No treatment (positive control), (9) No bacterial biofilm growth (negative control). The samples were incubated for 7days and colony-forming units (CFUs) were determined to evaluate bacterial viability. RESULTS The microbiological test revealed that aPDT groups, regardless the overall power, showed significant lower mean log10 CFU levels, than groups 3, 4 and 7 (p<0.01). The irrigation with 2.5% NaOCl and the combination of PDT and NaOCl achieved total elimination of bacteria. CONCLUSION These preliminary in vitro findings imply that the combination of ICG and NIR diode laser may be a novel supplement in aPDT and provide better disinfection during endodontic treatment.

Screening for antibiotic residues in swine and poultry tissues using the STAR test

During a 12-month period, 138 tissue samples (muscle, liver, kidney) were screened for antibiotic residues (ARs), using the five-plate STAR test. Samples positive to one or more antibiotics were detected in 33.9% of the chicken samples and in 26% of the pig samples. All the chicken liver samples, 32.2% of the chicken muscle and 14% of the swine liver samples were positive to sulphonamides and β-lactams, 25% of the kidney, 11.1% of the liver and 4% of the muscle tissue of the swine samples and 1.7% of the chicken muscle samples were positive to tetracycline, 12.5% of the kidney and 4% of the muscle swine samples were positive to aminoglycosides and macrolides. No quinolone residues were detected in any samples. The use of a microbiological method such as the STAR-test, for ARs screening in food is an effective low cost scheme indicating potential contamination with ARs.