Chrissanthy Papadopoulou

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.

Application of a Polymerase Chain Reaction Enzyme Immunoassay in Peripheral Whole Blood and Serum Specimens for Diagnosis of Acute Human Brucellosis

A simple polymerase chain reaction-enzyme immunoassay (PCR-EIA) was employed for the rapid laboratory diagnosis of human brucellosis directly from peripheral blood. Whole blood and serum specimens were collected from 243 patients with acute brucellosis as determined by blood culture, serological tests, and the patients’ clinical characteristics and from a control group of 50 healthy individuals. Diagnosis of brucellosis was established in 179 cases by isolation of Brucella spp. in blood culture and in 64 cases by clinical signs and serological investigation. Following the amplification of a 223-bp sequence of a gene that codes for the synthesis of an immunogenic membrane protein specific for the Brucella genus, the amplified product was detected in a microtiter plate by hybridization. Two hundred forty-one of the 243 patients tested had detectable Brucella DNA in either whole blood or serum specimens: 149 (61.3%) patients were positive in both whole blood and serum specimens, 43 (17.7%) were positive in serum specimens only, and 49 (20.2%) were positive in whole blood specimens only. The diagnostic specificity of the PCR-EIA assay for both specimen categories was 100%, while the sensitivity was 81.5% for whole blood specimens, 79% for serum specimens, and 99.2% for whole blood and serum specimens combined. The results suggest that the detection of Brucella DNA in whole blood and serum specimens by PCR-EIA assay is a sensitive and specific method that could assist the rapid and accurate diagnosis of acute human brucellosis.

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.

Intravitreal Dirofilariasis: A Rare Ocular Infection

Human ocular dirofilariasis is a zoonotic disease, rare in Europe, caused by filarial nematodes. The parasite is either encysted in a subcutaneous nodule or located under the bulbar conjunctiva. We report the case of a 62-year-old man with intravitreal dirofilariasis, which is a rare site of presentation of the nematode in the human eye. It was located in the fundus area and was surgically removed. The nematode was identified as Dirofilaria repens (D. conjuctiva) by two different Microbiology Departments, making this the fifth report of identified intravitreal dirofilariasis caused by D. repens in the relative literature.

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.

Microbial ethanol production: Experimental study and multivariate evaluation §

Ethanol can be produced from all the postmortem available substrates, though with higher rates and yields from carbohydrates, during the early stages of putrefaction. The so-called higher alcohols (1-propanol, isobutanol, 2-methyl-1-butanol and 3-methyl-2-butanol) and 1-butanol could be produced, from all the available postmortem substrates. However, a quantitative relationship between the produced ethanol and the potentially produced other alcohols is still missing. The objective of this study was the development of a simple, mathematical model which could be able to approximate the microbial produced ethanol in correlation with other produced alcohols. The selected bacterial species included two Gram+ spore-forming anaerobic bacteria and two (one Gram+ one Gram-) aerobic/facultative anaerobic bacteria, all being common commensals of the digestive tract and common colonizers of the corpse. The selected bacterial strains, Escherichia coli, Clostridium perfrigens, Clostridium sporogenes and Enterococcus faecalis, were cultured separately at 25 °C, for 30 days, under controlled anaerobic conditions. The produced ethanol and the previously referred alcohols were determined in the culture medium in 24h intervals. Using partial least squares (PLS) regression, the estimation of the relevance score for the available descriptors established the statistical model to assess the ethanol concentration produced by each studied microbe. E. coli, C. perfrigens, and C. sporogenes produced different patterns of ethanol and other alcohols, while E. faecalis produced negligible amounts of ethanol and higher alcohols. In constructing the mathematical models to predict the produced ethanol, 1-propanol, 1-butanol, and isobutanol were significant for C. perfrigens and C. sporogenes, while 1-butanol, 1-propanol, and methyl-butanol were significant for E. coli. The applicability of these models was tested in microbial, anaerobic cultures of normal human blood and plasma at 25 °C. The results indicate that factors such as the type of microbe species, the glucose content and the medium composition apparently affect the procedure of microbial ethanol, and other alcohols production. However, the models can be applied with acceptable accuracy and they show potential for application in real postmortem cases.

Changes in histamine and microbiological analyses in fresh and frozen tuna muscle during temperature abuse

Temperature abuse of tuna (Thunnus alalunga) was carried out in order to assess the histamine buildup in fish-processing facilities where fish can be exposed to high temperatures for short periods of time. Histamine production was studied in tuna loins under different storage and abuse conditions. Tuna was stored at 0–2°C, 3–4°C, and 6–7°C, and abused for 2 h daily at 20°C and 30°C for 7–12 days. Loins abused at 30°C for 2 h daily contained potentially toxic histamine concentrations (67–382 mg kg−1) when stored at a low refrigeration temperature (0–2°C), whereas when stored at 6–7°C, the loins contained highly toxic histamine concentrations (544.5–4156.6 mg kg−1). Lower histamine concentrations (23–48 mg kg−1 in loins stored at 0–2°C and 124.7–2435.8 mg kg−1 in loins stored at 6–7°C) were observed in temperature-abused loins that were initially frozen. An increase over time was observed in most microbial counts tested. Bacteria isolated from the temperature-abused loins showed a varied ability of histamine production, with Morganella morganii, Klebsiella oxytoca, Staphylococcus hominis, and Enterococcus hirae being the most active histamine-producing bacteria.

Diarrheic shellfish poisoning due to toxic mussel consumption: The first recorded outbreak in Greece

During the week of 14–20 January 2000, 120 people visited the Emergency Departments of hospitals in Thessaloniki, northern Greece, complaining of acute gastrointestinal illness after eating mussels (Mytilus galloprovincialis). The symptoms indicated diarrhoeic shellfish poisoning, and the toxicity of mussels harvested from Thermaikos Gulf in Thessaloniki during the outbreak was investigated using mouse bioassays. The bioassays revealed toxicity to mice by the mussel samples; while high numbers of toxic algae Dinophysis acuminata were identified in water samples from Thermaikos Gulf. The harvesting of mussels was immediately suspended and a monitoring programme for algal blooms was established from then onwards. During a follow-up of the mussels’ toxicity from January 2000 to January 2005, two more mussel samples were found positive for diarrheic shellfish poisoning: one harvested in March 2001 from the area of the outbreak (Thermaikos Gulf) and the other harvested in January 2001 from Amvrakikos Gulf in north-western Greece. However, no sporadic cases or outbreaks were reported during this period.

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.

Cryptosporidial infection in broiler chickens in Greece

Trachea, bursa of Fabricius, and small intestine of broilers 5 to 50 days of age from 10 flocks with varying levels of morbidity and mortality were screened for the presence of Cryptosporidium spp. Cryptosporidial oocysts were found in 24.2% of the examined birds.