Comparison of mCP and TSC Media to Enumerate Clostridium perfringens in Surface Water Samples.

The Clostridium perfringens bacteria are used to assess water quality as an indicator parameter. If detected, it can confirm the occurrence of past fecal contamination. Tests determining C. perfringens in water samples are usually performed by membrane filtration where filters are incubated on selective media under anaerobic conditions. Available media include mCP and TSC. The aim of this study was to compare the relative recovery of C. perfringens (including spores) from surface water samples and to determine the performance characteristics of the membrane filtration method using both media. The results showed that, although the procedure using the mCP medium was more sensitive and specific, higher recoveries were obtained in the tests based on the TSC medium.

Ciprofloxacin and nalidixic acid resistance of Salmonella spp. isolated from retail food in Poland.

Distribution of amino acid substitutions in the quinolone resistance-determining region (QRDR) of gyrA, gyrB, parC, parE and determinants of plasmid-mediated quinolone resistance (PMQR) were investigated among quinolone-resistant Salmonella spp. strains isolated from retail food in Poland in the years 2008-2013. Ten different amino acid substitutions were identified in QRDRs. Five different amino acid substitutions were identified in gyrA: Ser83Tyr, Ser83Phe, Asp87Tyr, Asp87Asn, Asp87Gly, two amino acid substitutions in parC: Thr57Ser, Ser80Ile and in parE: Leu445Phe, Arg511Ser. One substitution - Ser464Phe - was detected within gyrB. In gyrA a single substitution (Ser83Tyr) was identified the most frequently - 34.8% (63/181). Second most frequently identified variant (21.0%-38/181) was a co-existence of two single substitutions in gyrA: Ser83Tyr and parC: Thr57Ser. In four isolates co-existed three substitutions in three different genes: gyrA: Ser83Tyr + parC: Thr57Ser + parE: Leu445Phe (two isolates), gyrA: Ser83Phe + parC: Thr57Ser + parE: Leu445Phe, and gyrA: Ser83Tyr + parC: Thr57Ser + parE: Arg511Ser. In the two isolates four substitutions were identified - in gyrA: Ser83Phe + Asp87Tyr and in parC: Thr57Ser + Ser80Ile. Among resistant isolates, MIC values varied between 32 and 2048 mg/L (nalidixic acid) and between 0.125 and 16 mg/L (ciprofloxacin). MIC values of two isolates harboring qnrS1without any substitutions were 32 mg/L (NA) and 0.5-1.0 mg/L (CIP). The highest MIC values for NA and CIP were observed in two isolates of Salmonella spp. carrying double substitutions in gyrA: Ser83Phe + Asp87Tyr and parC: Thr57Ser + Ser80Ile. MIC value for NA was 2048 mg/L while for CIP - 16 mg/L.

Antimicrobial resistance of Salmonella spp. isolated from food

This review summarizes current data on resistance among Salmonella spp. isolates of food origin from countries in different regions of the world. The mechanisms of resistance to different groups of antimicrobial compounds are also considered. Among strains resistant to quinolones and/or fluoroquinolones the most prevalent mechanism is amino acid substitutions in quinolone resistance-determining region (QRDR) of genes gyrA, parC but mechanism of growing importance is plasmid-mediated quinolone resistance (PMQR) associated with genes qnrA, qnrB, qnrC, qnrD, qnrS but frequency of their detection is different. Resistance to sulfonamides is mostly associated with genes sul1 and sul2, while resistance to trimethoprim is associated with various variants of dhfr ( dfr) genes. Taking into account Salmonella spp. strains isolated from food, resistance to ß-lactams is commonly associated with ß-lactamases encoding by blaTEM genes. However strains ESBL and AmpC ­ positive are also detected. Resistance to aminoglicosides is commonly result of enzymatic inactivation. Three types of aminoglycoside modifying enzyme are: acetyltransferases (AAC), adenyltransferases (ANT) and phosphotransferases (APH). Resistance to tetracyclines among Salmonella spp. isolated from food is most commonly associated with active efflux. Among numerous genetic determinants encoding efflux pumps tetA, tetB, tetC, tetD, tetE and tetG are reported predominatingly. One of the most common mechanisms of resistance against chloramphenicol is its inactivation by chloramphenicol acetyltrasferases (CATs), but resistance to this compound can be also mediated by chloramphenicol efflux pumps encoded by the genes cmlA and floR. It is important to monitor resistance of Salmonella isolated from food, because the globalization of trade, leading to the long-distance

Occurrence and antimicrobial resistance of Salmonella spp. isolated from food other than meat in Poland.

INTRODUCTION AND OBJECTIVES: Antimicrobial resistance of pathogenic bacteria can result in therapy failure, increased hospitalization, and increased risk of death. In Poland, Salmonella spp. is a major bacterial agent of food poisoning. The majority of studies on antimicrobial resistance in Salmonella spp. isolates from food have focused on meat products as the source of this pathogen. In comparison, this study examines the antimicrobial susceptibility of Salmonella spp. isolated from retail food products other than meat in Poland. MATERIALS AND METHODS: A collection of 122 Salmonella spp. isolates were isolated in Poland in 2008-2012 from foods other than meat: confectionery products, eggs, fruits, vegetables, spices and others. The resistance of these isolates to 19 antimicrobial agents was tested using the disc diffusion method. RESULTS: Salmonella Enteritidis was the most frequently identified serotype (84.4% of all tested isolates). In total, 42.6% of the Salmonella spp. isolates were resistant to antibiotics. The highest frequencies of resistance were observed in isolates from 2009 (60.0%) and 2012 (59.5%). Antibiotic resistance was most prevalent among Salmonella spp. isolated from egg-containing food samples (68.0%). Resistance to nalidixic acid was most common and was observed in 35.2% of all tested isolates. The isolates were less frequently resistant to sulphonamides (6.6%), ampicillin (4.9%), amoxicillin/clavulanic acid (2.5%) and to streptomycin, cefoxitin, gentamicin and tetracycline (1.6%). Only one isolate showed resistance to chloramphenicol. Four isolates displayed multiresistance. CONCLUSIONS: Although, the level of resistance and multiresistance of Salmonella spp. isolates from non-meat foods was lower than in those from meat products, the presence of these resistant bacteria poses a real threat to the health of consumers.

Resistance to Sulfonamides and Dissemination of sul Genes Among Salmonella spp. Isolated from Food in Poland.

Antimicrobial resistance of pathogenic bacteria, including Salmonella spp., is an emerging problem of food safety. Antimicrobial use can result in selection of resistant organisms. The food chain is considered a route of transmission of resistant pathogens to humans. In many European countries, sulfonamides are one of the most commonly used antimicrobials. The aim of our investigation was to assess the prevalence of sul genes and plasmid occurrence among sulfonamide-resistant Salmonella spp. Eighty-four sulfonamide-resistant isolates were collected in 2008 and 2013 from retail products in Poland. Minimal inhibitory concentration of all of these isolates was ≥1024 µg/mL. Resistant isolates were tested for the presence of sul1, sul2, sul3, and int1 genes by using multiplex polymerase chain reaction. In total, 44.0% (37/84) isolates carried the sul1 gene, 46.4% (39/84) were sul2 positive, while the sul3 gene was not detected in any of the sulfonamide-resistant isolates tested. It was found that 3.6% (3/84) of resistant Salmonella spp. contained sul1, sul2, and intI genes. All 33 intI-positive isolates carried the sul1 gene. Eleven of the sulfonamide-resistant isolates were negative for all the sul genes. Most of the sulfonamide-resistant Salmonella spp. harbored plasmids; only in eight isolates were no plasmids detected. Generally, the size of the plasmids ranged from approximately 2 kb to ≥90 kb. Our results revealed a relatively a high prevalence of sulfonamides-resistant Salmonella spp. isolated from retail food. Additionally, we have detected a high dissemination of plasmids and class 1 integrons that may enhance the spread of resistance genes in the food chain.

Validation of direct plating of a stool sample as a method for Listeria monocytogenes detection.

The aim of current studies was to validate the direct plating of a stool sample for Listeria monocytogenes detection, using selective medium Palcam agar with Palcam selective supplement. Validation was performed using stool samples collected from healthy humans inoculated with Listeria sp. strains. Stool samples were frozen to determine the influence of freezing on method robustness. The presented research defines the Listeria monocytogenes limit of detection (LOD) as 10(3) cfu/g of stools for fresh and frozen samples. Repeatability and reproducibility of the method has been confirmed using statistical methods. We show the effectiveness of direct plating of stool samples on Palcam agar with Palcam selective supplement collected for Listeria monocytogenes detection. This method could be useful for this pathogen detection in stool samples collected from patients with diarrhoea.

[The new microbiological hazards in food]. / Nowe zagrozenia mikrobiologiczne w zywnosci.

This paper describes the new microbiological hazards in food. For protecting human health, nowadays food safety authorities face with many challenges, that years ago were largely unheard. In 2011 verocytotoxigenic Escherichia coli O104:H4 has been isolated in Germany. Strain came from fenugreek sprouts originated from Egypt. It was characterized by unique features such as presence of enteroaggregative Escherichia coli genes (aatA, aggR, aap, aggA, aggC) and resistance to most antibiotics. In Poland only three cases of disease caused by O104:H4 strain have been reported. Another emergence pathogen in Poland is Yersinia enterocolitica 08, biotype 1B. It is the most pathogenic bioserotype recently isolated in the USA only. Food-borne is commonly associated with raw or undercooked pork. The source of Yersinia spp. may be also milk and water. The presence ofbotulinum neurotoxins in food is not new, but still an important issue because of their high toxicity to human. Botulinum neurotoxins are high-molecular thermolabile proteins produced by Clostridium botulinum and some strains of Clostridium butyricum and Clostridium baratii. Based on their antigenic properties, botulin neurotoxins are divided into seven types A-G, however only types A, B, E and F are toxic to humans and some animals. Increasing risk associated with food results from antimicrobial resistance eg. extended spectrum beta-lactamases (ESBLs) producing bacteria, particularly Enterobacteriaceae. Until recently strains ESBL+ were isolated in hospitals, however during last years they have been isolated from healthy humans, animals and food of animal origin. Increasingly common microbiological hazard in food is methicillin-resistant Staphylococcus aureus (MRSA). Although prevalence of this pathogen in food is not high, the thread comes from difficulties of treating of infections caused by MRSA. The occurrence of food-borne in humans may also be associated with presence of viruses in food and water. The carrier of viruses may be equipment in food plant, production line, packaging and man. Most food-borne are caused by noroviruses, rotaviruses, hepatitis A virus and hepatitis E virus. An increased number of food-borne viral outbreaks are recorded in several countries. Reasons for this include the improved diagnostic methods that have enhanced detection of some virus groups, and the increased marketing of fresh and frozen foods that has led to a worldwide availability of high risk food. Viruses may contaminate food either through contamination at source, principally through sewage pollution of the environment, or in association with food