Fecal carriage of extended-spectrum beta-lactamase-producing Enterobacteriaceae in swine and cattle at slaughter in Switzerland

During the past decade, extended-spectrum beta-lactamase (ESBL)-producing Enterobacteriaceae have become a matter of great concern in human medicine. ESBL-producing strains are found in the community, not just in hospital-associated patients, which raises a question about possible reservoirs. Recent studies describe the occurrence of ESBL-producing Enterobacteriaceae in meat, fish, and raw milk; therefore, the impact of food animals as reservoirs for and disseminators of such strains into the food production chain must be assessed. In this pilot study, fecal samples of 59 pigs and 64 cattle were investigated to determine the occurrence of ESBL-producing Enterobacteriaceae in farm animals at slaughter in Switzerland. Presumptive-positive colonies on Brilliance ESBL agar were subjected to identification and antibiotic susceptibility testing including the disc diffusion method and E-test ESBL strips. As many as 15.2% of the porcine and 17.1% of the bovine samples, predominantly from calves, yielded ESBL producers. Of the 21 isolated strains, 20 were Escherichia coli, and one was Citrobacter youngae. PCR analysis revealed that 18 strains including C. youngae produced CTX-M group 1 ESBLs, and three strains carried genes encoding for CTX-M group 9 enzymes. In addition, eight isolates were PCR positive for TEM beta-lactamase, but no bla(SHV) genes were detected. Pulsed-field gel electrophoresis showed a high genetic diversity within the strains. The relatively high rates of occurrence of ESBLproducing strains in food animals and the high genetic diversity among these strains indicate that there is an established reservoir of these organisms in farm animals. Further studies are necessary to assess future trends

Low occurrence of Clostridium difficile in fecal samples of healthy calves and pigs at slaughter and in minced meat in Switzerland

Clostridium difficile is a cause of diarrhea and colitis in humans. The increase of incidence and severity of C. difficile infections in humans in past years is due, at least in part, to the emergence of more virulent strains (PCR ribotypes 027 and 078). Recent studies describe the occurrence of hypervirulent strains in ground meat products. Therefore, food animals and food need to be assessed for their possible role as vectors of C. difficile to humans. In this pilot study, fecal samples of 204 calves and 165 pigs, as well as 46 minced meat products were investigated to determine the occurrence of C. difficile in farm animals at slaughter and in ground meat products at the retail level in Switzerland. C. difficile was isolated from only one fecal sample of a calf. All samples from pigs and ground meat were negative. Further characterization revealed that the isolated strain harbored genes for toxins A and B as well as binary toxin, and belonged to the ribotype 078. Based on these results, low occurrence of C. difficile in farm animals at slaughter and retail ground meat in Switzerland is postulated. However, further studies are necessary to confirm these preliminary data and to assess future trends

Low occurrence of Clostridium difficile in fecal samples of healthy calves and pigs at slaughter and in minced meat in Switzerland

Clostridium difficile is a cause of diarrhea and colitis in humans. The increase of incidence and severity of C. difficile infections in humans in past years is due, at least in part, to the emergence of more virulent strains (PCR ribotypes 027 and 078). Recent studies describe the occurrence of hypervirulent strains in ground meat products. Therefore, food animals and food need to be assessed for their possible role as vectors of C. difficile to humans. In this pilot study, fecal samples of 204 calves and 165 pigs, as well as 46 minced meat products were investigated to determine the occurrence of C. difficile in farm animals at slaughter and in ground meat products at the retail level in Switzerland. C. difficile was isolated from only one fecal sample of a calf. All samples from pigs and ground meat were negative. Further characterization revealed that the isolated strain harbored genes for toxins A and B as well as binary toxin, and belonged to the ribotype 078. Based on these results, low occurrence of C. difficile in farm animals at slaughter and retail ground meat in Switzerland is postulated. However, further studies are necessary to confirm these preliminary data and to assess future trend

Spectrally selective solar absorber stable up to 900 °C for 120 h under ambient conditions

Concentrated solar power (CSP) technology, which converts sunlight into heat and then electricity, is an attractive alternative to photovoltaics because of its high capacity for thermal-energy storage, which can be converted to electricity after sunset. As the efficiency of this technology is limited by the Carnot efficiency, higher absorber temperatures are desirable. At high temperatures the conversion efficiency is limited by the heat loss from solar absorbers via radiation in infrared wavelengths. Hence, it is desirable to develop selective solar absorbers, which can absorb solar radiation while reflecting infrared radiation. It is also important to develop high temperature selective solar absorbers, which can work in ambient conditions to reduce cost as compared to those that work under vacuum. Here, we report a selective solar absorber made of black chrome/ITO/SiO , deposited on stainless steel, which showed stable performance at 900 °C under ambient conditions for 120 h. The proposed selective solar absorber exhibits an absorptance of 0.9 in the solar spectrum with an infrared emittance of 0.4 beyond wavelengths of 6 μm.

In vitro inhibition activity of different bacteriocin-producing E. coli against Salmonella strains isolated from clinical cases

Aims: To compare in vitro the inhibitory activity of four bacteriocin producing E. coli to a well-characterized panel of Salmonella strains, recently isolated from clinical cases in Switzerland. Methods and Results: A panel of 68 non-typhoidal Salmonella strains was characterized by PFGE analysis and susceptibility to antibiotics. The majority of tested strains were genetically different, with 40% resistant to at least one antibiotic. E. coli Mcc24 showed highest in vitro activity against Salmonella (100%, microcin 24), followed by E. coli L1000 (94%, microcin B17), E. coli 53 (49%, colicin H) and E. coli 52 (21%, colicin G) as revealed using a cross-streak activity assay. Conclusion: E. coli Mcc24, a genetically modified organism producing microcin 24, and E. coli L1000, a natural strain isolated from human feces carrying the mcb-operon for microcin B17-production, were the most effective strains in inhibiting in vitro both antibiotic resistant and sensitive Salmonella isolates. Significance and Impact of the Study: Due to an increasing prevalence of antibiotic resistant Salmonella strains, alternative strategies to fight these foodborne pathogens are needed. E. coli L1000 appears to be a promising candidate in view of developing biotechnological alternatives to antibiotics against Salmonella infections