Jobstl M.,Austrian Agency for Health and Food Safety AGES |
Heuberger S.,IMED AGES Graz |
Indra A.,IMED AGES Vienna |
Nepf R.,Austrian Agency for Health and Food Safety AGES |
And 2 more authors.
International Journal of Food Microbiology | Year: 2010
Prevalence of Clostridium difficile was examined in Austrian ground meat samples and bactofugates, following an evaluation of enrichment broths. Bactofugation is a centrifugation procedure used at sensitive dairies to lower the concentration of spores in raw milk before heat treatment. Among the five enrichment broths tested, C. difficile moxalactam norfloxacin boullion (CDMN) was the only one that allowed recovery of C. difficile from artificially spiked meat samples. Use of Tween 80 as a detergent in the enrichment of artificially contaminated bactofugates improved recovery of C. difficile. Following the enrichment procedures (meat without the use of TWEEN 80), one hundred ground meat samples and fifty bactofugates were enriched for 10-15 days in CDMN and presumed positive colonies were isolated and identified by Gram staining, observation of colony fluorescence and ID 32 A ribotyping. Subsequently PCR ribotyping, PCR-based identification of toxin genes (tcdA, tcdB) and antimicrobial drug susceptibility testing to metronidazole, vancomycin, clindamycin and moxifloxacin were performed. C. difficile was isolated from three (3%) of the one hundred retail ground meat samples. Two C. difficile isolates of the same rare ribotype AI-57 were toxin gene-negative and sensitive to all antibiotics tested. One isolate was assignable to one of the most prevalent clinical ribotypes isolated in Austria and harboured the tcdA and tcdB genes. This isolate was also resistant to clindamycin and moxifloxacin. None of the fifty bactofugates tested were positive for C. difficile. The presence of an isolate of human origin could indicate contamination by human shedders during food processing rather than evidencing zoonotic potential. Bactofugates, although constituting concentrated spore suspensions, were not contaminated with C. difficile spores. This finding excludes raw milk as a major source of food contamination. In conclusion, C. difficile recovery rates found in our study were lower than expected from the literature. Sources other than zoonotic origin must be considered when studying the epidemiology of community acquired infections with this bacterium. © 2010 Elsevier B.V. All rights reserved.
Allerberger F.,Austrian Agency for Health and Food Safety AGES |
Wagner M.,Institute for Milk Hygiene
Clinical Microbiology and Infection | Year: 2010
Listeria monocytogenes is the causative agent of human listeriosis, a potentially fatal foodborne infection. Clinical manifestations range from febrile gastroenteritis to more severe invasive forms, including sepsis, meningitis, rhombencephalitis, perinatal infections, and abortions. In recent years, an increasing rate of listeriosis has been reported in several European countries. These increases primarily reflect a higher rate of bacteraemic listeriosis in those ≥65 years of age, and are not otherwise correlated with geography, gender, ethnicity, socioeconomic factors or infectious serotypes. In the late 1980s, an upsurge in listeriosis rates was due to the contamination of a small number of food products. However, a restricted range of strains was responsible for most of the additional cases at that time, and no evidence exists for such a pattern since 2001. From a clinical perspective, the importance of isolating the pathogen as a prerequisite for an accurate epidemiological investigation and ultimately stopping transmission cannot be overemphasized. © 2009 The Authors. Journal Compilation © 2009 European Society of Clinical Microbiology and Infectious Diseases.
Schoder D.,Institute for Milk Hygiene |
Skandamis P.,Agricultural University of Athens |
Wagner M.,Institute for Milk Hygiene
International Journal of Food Microbiology | Year: 2013
A cluster of 34 cases of listeriosis was traced to consumption of quargel cheese, a sour milk specialty, in Austria, Germany and Czech Republic between 2009 and 2010. After recall from the retail market all soft cheese batches (n=18) were sent for investigation and ISO 11290 based microbiological analysis revealed all red smear-ripened batches (16/18) to be positive for Listeria monocytogenes whereas mold ripened cheeses were negative. The 16 positive batches were grouped into three categories: those having exceeded shelf-life (G1), those around shelf-life (±4days, G2) and those within shelf-life (G3). Tracing the contamination levels as measured after recall (CLR) to the theoretical contamination level after processing (CL0) was considered to provide an estimate as to whether the in-house monitoring system would have been capable of unraveling the contamination scenario. Growth simulations starting from various hypothetical initial contamination levels of cheese at the plant and considering the potential variability in growth of L. monocytogenes due to model parameters and storage conditions suggested that a very low initial contamination level (e.g., <1CFU/g or 5CFU/100g) could justify the levels of L. monocytogenes enumerated in recalled samples of G1 and G2 lots. This in turn, may have resulted in low detection probability using ISO 11290:1996. In lots of G3 group, however, high initial contamination levels or temperature abuse at retail are inferred, based on simulated outputs. © 2013 Elsevier B.V.
Reindl A.,Institute for Milk Hygiene |
Reindl A.,Federal Institute for Alpine Dairying |
Dzieciol M.,Institute for Milk Hygiene |
Hein I.,Institute for Milk Hygiene |
And 2 more authors.
Journal of Dairy Science | Year: 2014
A membrane filtration technique developed for counting butyric acid bacteria in cow milk was further developed for analysis of goat milk. Reduction of the sample volume, prolongation of incubation time after addition of proteolytic enzyme and detergent, and a novel step of ultrasonic treatment during incubation allowed filtration of goat milk even in the case of somatic cell counts (SCC) exceeding 106/mL. However, filterability was impaired in milk from goats in late lactation. In total, spore counts were assessed in 329 farm bulk goat milk samples. Membrane filtration technique counts were lower than numbers revealed by the classic most probable number technique. Thus, method-specific thresholds for milk to evaluate the risk of late blowing have to be set. As expected, the spore counts of milk samples from suppliers not feeding silage were significantly lower than the spore counts of milk samples from suppliers using silage feeds. Not only were counts different, the clostridial spore population also varied significantly. By using 16S rRNA gene PCR and gene sequencing, 342 strains from 15 clostridial species were identified. The most common Clostridium species were Clostridium tyrobutyricum (40.4%), Clostridium sporogenes (38.3%), Clostridium bifermentans (7.6%), and Clostridium perfringens (5.3%). The 2 most frequently occurring species C. tyrobutyricum and C. sporogenes accounted for 84.7% of the isolates derived from samples of suppliers feeding silage (n=288). In contrast, in samples from suppliers without silage feeding (n=55), these species were detected in only 45.5% of the isolates. © 2014 American Dairy Science Association.