Molecular Tracing to Find Source of Protracted Invasive Listeriosis Outbreak, Southern Germany, 2012-2016.

We investigated 543 Listeria monocytogenes isolates from food having a temporal and spatial distribution compatible with that of the invasive listeriosis outbreak occurring 2012-2016 in southern Germany. Using forensic microbiology, we identified several products from 1 manufacturer contaminated with the outbreak genotype. Continuous molecular surveillance of food isolates could prevent such outbreaks.

ChromID® CARBA Agar Fails to Detect Carbapenem-Resistant Enterobacteriaceae With Slightly Reduced Susceptibility to Carbapenems.

After first detections of carbapenemase-producing Enterobacteriaceae (CPE) in animals, the European Union Reference Laboratory for Antimicrobial Resistance has provided a protocol for the isolation of carbapenemase-producing Escherichia (E.) coli from cecum content and meat. Up to now, only few isolates were recovered using this procedure. In our experience, the choice of the selective agar is important for the efficacy of the method. Currently, the use of the prevailing method fails to detect CPE that exhibit a low resistance against carbapenems. Thus, this study aims to evaluate the suitability of selective media with antibiotic supplements and commercial ChromID® CARBA agar for a reliable CPE detection. For comparative investigations, detection of freeze-dried carbapenemase-resistant bacteria was studied on different batches of the ChromID® CARBA agar as well as on MacConkey agar supplemented with 1 mg/L cefotaxime and 0.125 mg/L meropenem (McC+CTX+MEM). The suitability of the different media was assessed within a time of 25 weeks, starting at least six weeks before expiration of the media. Carbapenem-resistant isolates exhibiting a serine-based hydrolytic resistance mechanism (e.g., bla KPC genes) were consistently detected over 25 weeks on the different media. In contrast, carbapenemase producers with only slightly reduced susceptibility and exhibiting a zinc-catalyzed activity (e.g., bla VIM, bla NDM, and bla IMP) could only be cultivated on long-time expired ChromID® CARBA, but within the whole test period on McC+CTX+MEM. Thus, ChromID® CARBA agar appears to be not suitable for the detection of CPE with slightly increased minimum inhibitory concentrations (MIC) against carbapenems, which have been detected in German livestock and thus, are of main interest in the national monitoring programs. Our data are in concordance with the results of eleven state laboratories that had participated in this study with their ChromID® CARBA batches routinely used for the German CPE monitoring. Based on the determined CPE detection rate, we recommend the use of McC+CTX+MEM for monitoring purposes. This study indicates that the use of ChromID® CARBA agar might lead to an underestimation of the current CPE occurrence in food and livestock samples.

[Prevalence of Campylobacter spp. in poultry meat and raw milk using PCR, conventional cultural methods and Fourier transform infrared spectroscopy]. / Untersuchungen zur Prävalenz von Campylobacter spp. in Geflügelfleisch und Rohmilch mittels PCR, konventioneller kultureller Methode und Fourier-Transformations-Infrarotspektroskopie.

The identification of thermotolerant campylobacters in official food control in the state of Baden-Wuerttemberg has been traditionally performed using the cultural procedure as described in the ISO-Norm 10272:1995. Analysis thus took 5-6 days to complete. Additionally diagnostic problems caused by the accompanying flora as well as the resistance to nalidixic acid occured. Within the scope of this study these problems could be solved by introducing a filtration step for the reduction of the accompanying flora and by performing the indoxyl acetate-hydrolysis-test in addition to the antibiotic-resistance-test. Besides various PCR protocols for the identification of thermotolerant campylobacters from food were established as an alternative to the cultural procedure, providing reliable results within two days. Furthermore, infrared spectroscopy was tested for the identification of Campylobacter isolates. Using this technique and with the help of a suitable data base, bacterial pure cultures can be differentiated within 2 hours. Among others 356 samples of raw poultry meat were tested with the newly established procedures as well as with the classical cultural method, showing that 32% of the samples were Campylobacter spp. positive. 37% of these isolates were resistant against nalidixic acid. This indicates that the development of resistances in Campylobacter spp. in Germany follows the same trend described for other European countries.

[Brain emboli in the lungs of cattle]. / ZNS-Emboli in der Rinderlunge.

There is no information whether the BSE agent is introduced into the human food chain through contamination of the lungs of cattle with central nervous system tissue (CNS). Studies in the United Kingdom and in the USA showed that CNS tissue could contaminate the lungs after using pneumatic powered air injection stunners (e.g. "The Knocker") or after pithing. Thus, pithing was forbidden in the European Union since January 2001. In German abattoirs conventional cartridge-fired stunners (e.g. model by Schermer) are usually applied. Pithing was used up to December 2000 in approx. 75% of the German abattoirs. In the present study 323 lungs of cattle were analysed for CNS. The lungs were derived from cattle exclusive stunned by use of the knocker from Schermer. 60% of the lungs contained emboli which were tested with immuno chemistry as well as immuno histochemistry to detect CNS. Two of 108 pooled samples showed a faint immuno reaction in the anti-NSE and anti-GFAP immunoblot. Further two particles showed a faint reaction for NSE and GFAP in immuno histochemistry, thus suggesting the presence of CNS. Even though CNS tissue could not be shown in the histological investigation, we used our findings to estimate the worst case scenario for human BSE exposure risk (HER) by lung contaminated by CNS emboli. The content of CNS in the samples was estimated to be about 0.11% when the respective immuno reactions were calibrated against standards containing known brain concentrations. Under the assumption that only one lung in the pooled samples was contaminated with BSE-infected central nervous tissue, the HER was calculated to reach a maximum of 2.2 x 10(-5) CoID50/consumer after consumption of a sausage with a portion of 10% lung. The results of our study suggest that the contamination of the lung with CNS after using a conventional cartridge-fired stunner cannot be excluded, however, the incidence appears to be very low. In addition, presumed CNS emboli, if at all, are microscopically small. Furthermore the incidence of BSE in Germany is very low and lungs of cattle are usually not consumed. Thus we can judge the potential for human oral exposure after consumption of lungs of cattle which were stunned in Germany to be extremely low. A final assessment, however, is impossible as there is no knowledge about the minimum infectious dose for humans.