Antimicrobial resistance and R-factor transfer of salmonellae isolated from chicken carcasses in Greek hospitals

A total of 62 salmonellae, belonging to six different serotypes, were isolated from 60 out of 87 (69.0%) chicken carcasses delivered to hospitals of Thesssaloniki, Greece. Salmonella enteritidis, Salmonella anatum and Salmonella bredeney were the most prevalent serovars. Isolates were examined for antibiotic resistance patterns and R-determinants. Resistance to at least one antibiotic was observed in 36 (58.1%) of them and 18 different resistant profiles were recorded. Nitrofurantoin-resistance was the most common (29.0%), followed by spectinomycin (21.0%), ampicillin (19.4%) and ticarcillin (19.4%). Fourteen (38.9%) of the resistant isolates possessed R-factors and resistance to ampicillin, ticarcillin, trimethoprim and kanamycin was easily self-transferable. However, nitrofurantoin- and spectinomycin-resistance although prevailing, was not found transferable even after mobilization. The high incidence of antibiotic resistant salmonellae among chicken carcasses in our hospital setting suggests the need for public health interventions and possible withdrawal of drug selective pressure.     

Degradation of lincomycin in aqueous medium: Coupling of solar photocatalysis and membrane separation

The photocatalytic oxidation of a common antibiotic, the lincomycin was carried out in aqueous suspensions of polycrystalline TiO₂ Degussa P25 irradiated by sunlight. In order to improve the performance of the lincomycin degradation a hybrid system consisting of a solar photoreactor with the photocatalyst in suspension coupled with a membrane module, used to confine both photocatalyst and pollutants in the reaction environment, was tested.A preliminary study was carried out in order to determine some kinetics parameters of the drug photodegradation. The influence of initial substrate concentration on the lincomycin photooxidation rate was investigated. The photooxidation rate follows a pseudo-first order kinetics with respect to the lincomycin concentration under the used experimental conditions. The presence of the membrane reactor allows the catalyst separation and to operate in continuous mode as the membranes rejection for lincomycin and its oxidation products was quite high.     

A survey of the occurrence and properties of methicillin‐resistant Staphylococcus aureus and methicillin‐resistant Staphylococcus intermedius in water buffalo milk and dairy products in Turkey

Antimicrobial resistance, β‐lactamase activity and mecA gene of Staphylococcus aureus and Staphylococcus intermedius isolated from raw water buffalo milk and dairy products in Turkey were determined. All strains showed resistance to at least one antibiotic but none was resistant to vancomycin. Of the 97 S. aureus and 35 S. intermedius strains, 9 (9.2%) and 2 (5.7%) were resistant to oxacillin and harboured mecA gene. β‐lactamase activity of 13.4% and 5.7% of S. aureus and S. intermedius strains was positive, respectively. Overall, 2.5% and 0.55% of the samples were contaminated with methicillin‐resistant S. aureus and S. intermedius, respectively.     

Antibiotic resistance of coagulase-negative staphylococci associated with food and used in starter cultures

The resistance of 330 coagulase-negative staphylococci (CNS) associated with food or used in starter cultures and belonging to the species Staphylococcus carnosus, Staphylococcus condimenti, Staphylococcus piscifermentans, Staphylococcus equorum, Staphylococcus succinus and Staphylococcus xylosus, against 21 antibiotics was determined using the disk diffusion method. The incidence and number of resistances was found to be species and source of isolation dependent. Most strains of S. equorum (63%), S. succinus (90%) and S. xylosus (95%) exhibited resistances against up to seven antibiotics, whereas only few strains of S. carnosus (12%) and S. piscifermentans (27%) were antibiotic resistant. Resistances to lincomycin, penicillin, fusidic acid, oxacillin, ampicillin and tetracycline were predominant. Among strains of S. xylosus, the incidence of resistance ranged from 22% for tetracycline up to 69% for penicillin. Concerning the source of isolation, resistances were often determined in strains of S. equorum, S. succinus and S. xylosus isolated from cheese (87%) and sausage (83%), and strains of S. xylosus obtained from meat starter cultures (93%). Remarkably, all CNS were sensitive to the clinically important antibiotics chloramphenicol, clindamycin, cotrimoxazol, gentamicin, kanamycin, linezolid, neomycin, streptomycin, synercid and vancomycin. The phenotypic resistances to ss-lactam antibiotics, lincomycin and tetracycline were verified by PCR amplification and could be traced back to the genes blaZ, lnuA and tetK, respectively. This study permitted a comprehensive insight into the incidence of antibiotic resistances in food-associated CNS.     

乳酸链球菌素在食品工业中的应用

介绍了乳酸链球菌素(Nisin)的分子结构、稳定性、安全性和抗菌机理的研究进展；综述了乳酸链球菌素在食品工业中的应用现状，并对其应用前景进行展望。     

Identification and antibiotic resistance of Lactobacilli isolated from raw cow’s milk of Oujda City (Morocco)

In this study, a Lactobacillus strain was isolated from raw cow milk. It was tentatively identified at the species level according to its carbohydrate fermentation profile and phenotype characteristics as Lactobacillus paracasei KSNM. The susceptibility of the identified Lactobacillus to 23 antibiotics was performed using the disc diffusion testing method. Inhibition zone diameters were measured and expressed in terms of sensitive, intermediate or resistant. KSNM strain was sensitive toward; amoxicillin, ampicillin, amoxyclav (amoxicillin + clavulanic acid), tetracycline, macrolides, sulfamides/trimethoprim, and rifampicin. But, it expressed intermediate sensitivity toward; cefamandole, cefaclor, and cephalothin. However, it was resistant to penicillin G, aminoglycosides, quinolones, ciprofloxacin, lincomycin, nitroxolin, and a large number of cephalosporins, which included cefoxitin, cefotaxime, and ceftriaxone.     

Prevalence,acquired antibiotic resistance and bacteriocin production of Enterococcus spp. isolated from tunisian fermented food products

In this study, a total of 100 fermented food products including dairy (Lben, Rayeb, Rigouta, and Jben) olive and vegetable products, harvested in Northwestern Tunisia, were investigated for the presence of Enterococcus spp. Our results showed high levels of contamination with Enterococcus spp., identified according to standard bacteriological, biochemical and phenotypic criteria. 143 isolates were recovered; E. faecium (46.15%) was the predominant species, followed by E. faecalis (27.27%), E. casseliflavus (12.58%), E. durans (8.39%) and E. mundtii (5.59%). None of the isolates showed acquired resistance againts clinically relevant drugs used for enterococcal infections treatment in human medicins, and no haemolytic activity was demonstrated. Furthermore, over 50% of the isolates within each species exhibited antilisterial bacteriocin production. Further data are needed to enhance understanding of bacteriocin production of enterococci in fermented food products as well as the potential risks to quality and safety, including possible transmission of antibiotic resistant organisms to human consumers.     

基于太赫兹光谱技术的抗生素类药物检测研究

本文利用太赫兹时域光谱技术在室温下对几种在临床和人们日常生活中常用的抗生素类药物阿莫西林、青霉素钠、头孢氢氨苄和头孢拉丁进行了光谱测量,获得了四种物质在0.2-1.7THz波段的吸收谱和折射谱,发现这四种抗生素类药物在太赫兹波段均存在明显的特征吸收峰,可作为其在太赫兹波段的指纹谱用于药物分子识别。本研究表明,太赫兹时域光谱技术在常用抗生素类药物的物质鉴别及药品质量检查方面有着广泛的应用前景。     

Kinetics of growth and inactivation of Salmonella enterica serotype Typhimurium DT104 in pasteurised liquid egg products

The potential impact of post-pasteurisation contamination of liquid egg products with the multi-antibiotic resistant pathogen Salmonella enterica serotype Typhimurium definitive type 104 (DT104) was assessed by determining the viability of this bacterium in whole egg, albumen and 10% w/w sugared and salted yolk incubated at 4–42 °C. Results indicated that populations of S. Typhimurium DT104 were slowly inactivated in all four products when stored at 4 °C. However, based on the typical shelf-lives of cold-stored liquid egg, less than 0.6 log-kill would be achieved in those products prior to their use. Incubation at temperatures pertaining to abuse situations (10, 15, 20 and 25 °C) revealed an increasing potential for growth of S. Typhimurium DT104 in whole egg, albumen and sugared yolk, as indicated by trends in growth rate, lag duration and maximum population density. At even higher temperatures (30, 37 and 42 °C), growth rates of S. Typhimurium DT104 in whole egg and sugared yolk continued to increase. The same was true for S. Typhimurium DT104 in albumen except that growth was not observed at 42 °C and instead populations were inactivated within 30 h. At no temperature tested was S. Typhimurium DT104 able to grow in salted yolk. The influence of these growth and inactivation patterns on the risk of salmonellosis in relation to product type and storage temperature is discussed.     

Contamination of post-harvest poultry products with multidrug resistant Staphylococcus aureus in Maryland-Washington DC metro area

We investigated the prevalence of Staphylococcus aureus and multidrug including methicillin-resistant S. aureus (MRSA) in poultry retail meat samples from the Maryland-Washington DC metro area. A total of 24 S. aureus isolates were recovered from 96 whole poultry carcass samples and the prevalence of S. aureus were 25.0%, 14.29%, and 33.3% in retail poultry meats collected from farmers markets, organic and conventional retail supermarkets, respectively. Both single and multi-drug resistance isolates were detected in 58.3% (7/12) isolates from conventional retail meat products but none from farmers markets or organic retail meat isolates. Conventional retail meat isolates were found to be resistant to both erythromycin (50.0%) and tetracycline (58.3%). We also detected an MRSA isolate harboring mecA gene in conventional retail meat which showed co-resistance towards erythromycin, tetracycline, and vancomycin.