Diversity and Resistance Profiles of Human Non-typhoidal Salmonella spp. in Greece, 2003-2020.

Salmonella spp. is one of the most common foodborne pathogens in humans. Here, we summarize the laboratory surveillance data of human non-typhoidal salmonellosis in Greece for 2003-2020. The total number of samples declined over the study period (p < 0.001). Of the 193 identified serotypes, S. Enteritidis was the most common (52.8%), followed by S. Typhimurium (11.5%), monophasic S. Typhimurium 1,4,[5],12:i:- (4.4%), S. Bovismorbificans (3.4%) and S. Oranienburg (2.4%). The isolation rate of S. Enteritidis declined (p < 0.001), followed by an increase of the less common serotypes. Monophasic S. Typhimurium has been among the five most frequently identified serotypes every year since it was first identified in 2007. Overall, Salmonella isolates were resistant to penicillins (11%); aminoglycosides (15%); tetracyclines (12%); miscellaneous agents (sulphonamides, trimethoprim, chloramphenicol and streptomycin) (12%) and third-generation cephalosporins (2%). No isolate was resistant to carbapenems. In total, 2070 isolates (24%) were resistant to one or two antimicrobial classes and 903 (10%) to three and more. Out of the 1166 isolates resistant to fluoroquinolones (13%), 845 (72%) were S. Enteritidis. S. Enteritidis was also the most frequently identified serotype with a resistance to third-generation cephalosporins (37%, 62/166), followed by S. Typhimurium (12%, 20/166). MDR was most frequently identified for S. Typhimurium and its monophasic variant (resistant phenotype of ampicillin, streptomycin, tetracycline and sulphamethoxazole with or without chloramphenicol or trimethoprim).

Long term transcriptional and behavioral effects in mice developmentally exposed to a mixture of endocrine disruptors associated with delayed human neurodevelopment.

Accumulating evidence suggests that gestational exposure to endocrine disrupting chemicals (EDCs) may interfere with normal brain development and predispose for later dysfunctions. The current study focuses on the exposure impact of mixtures of EDCs that better mimics the real-life situation. We herein describe a mixture of phthalates, pesticides and bisphenol A (mixture N1) detected in pregnant women of the SELMA cohort and associated with language delay in their children. To study the long-term impact of developmental exposure to N1 on brain physiology and behavior we administered this mixture to mice throughout gestation at doses 0×, 0.5×, 10×, 100× and 500× the geometric mean of SELMA mothers' concentrations, and examined their offspring in adulthood. Mixture N1 exposure increased active coping during swimming stress in both sexes, increased locomotion and reduced social interaction in male progeny. The expression of corticosterone receptors, their regulator Fkbp5, corticotropin releasing hormone and its receptor, oxytocin and its receptor, estrogen receptor beta, serotonin receptors (Htr1a, Htr2a) and glutamate receptor subunit Grin2b, were modified in the limbic system of adult animals, in a region-specific, sexually-dimorphic and experience-dependent manner. Principal component analysis revealed gene clusters associated with the observed behavioral responses, mostly related to the stress axis. This integration of epidemiology-based data with an experimental model increases the evidence that prenatal exposure to EDC mixtures impacts later life brain functions.

A Novel Approach to Chemical Mixture Risk Assessment-Linking Data from Population-Based Epidemiology and Experimental Animal Tests.

Humans are continuously exposed to chemicals with suspected or proven endocrine disrupting chemicals (EDCs). Risk management of EDCs presents a major unmet challenge because the available data for adverse health effects are generated by examining one compound at a time, whereas real-life exposures are to mixtures of chemicals. In this work, we integrate epidemiological and experimental evidence toward a whole mixture strategy for risk assessment. To illustrate, we conduct the following four steps in a case study: (1) identification of single EDCs ("bad actors")-measured in prenatal blood/urine in the SELMA study-that are associated with a shorter anogenital distance (AGD) in baby boys; (2) definition and construction of a "typical" mixture consisting of the "bad actors" identified in Step 1; (3) experimentally testing this mixture in an in vivo animal model to estimate a dose-response relationship and determine a point of departure (i.e., reference dose [RfD]) associated with an adverse health outcome; and (4) use a statistical measure of "sufficient similarity" to compare the experimental RfD (from Step 3) to the exposure measured in the human population and generate a "similar mixture risk indicator" (SMRI). The objective of this exercise is to generate a proof of concept for the systematic integration of epidemiological and experimental evidence with mixture risk assessment strategies. Using a whole mixture approach, we could find a higher rate of pregnant women under risk (13%) when comparing with the data from more traditional models of additivity (3%), or a compound-by-compound strategy (1.6%).

Gestational exposure to an epidemiologically defined mixture of phthalates leads to gonadal dysfunction in mouse offspring of both sexes.

The increasing concern for the reproductive toxicity of abundantly used phthalates requires reliable tools for exposure risk assessment to mixtures of chemicals, based on real life human exposure and disorder-associated epidemiological evidence. We herein used a mixture of four phthalate monoesters (33% mono-butyl phthalate, 16% mono-benzyl phthalate, 21% mono-ethyl hexyl phthalate, and 30% mono-isononyl phthalate), detected in 1st trimester urine of 194 pregnant women and identified as bad actors for a shorter anogenital distance (AGD) in their baby boys. Mice were treated with 0, 0.26, 2.6 and 13 mg/kg/d of the mixture, corresponding to 0x, 10x, 100x, 500x levels detected in the pregnant women. Adverse outcomes detected in the reproductive system of the offspring in pre-puberty and adulthood included reduced AGD index and gonadal weight, changes in gonadal histology and altered expression of key regulators of gonadal growth and steroidogenesis. Most aberrations were apparent in both sexes, though more pronounced in males, and exhibited a non-monotonic pattern. The phthalate mixture directly affected expression of steroidogenesis as demonstrated in a relevant in vitro model. The detected adversities at exposures close to the levels detected in pregnant women, raise concern on the existing safety limits for early-life human exposures and emphasizes the need for re-evaluation of the exposure risk.

Perinatal exposure to low-dose bisphenol A affects the neuroendocrine stress response in rats.

Bisphenol A (BPA) is an estrogen-mimicking endocrine disruptor. Early-life exposures to low doses of BPA exert long-lasting effects on animals' reproductive and brain physiology. However, little is known about the effects of BPA on the stress-response system. Given the interaction of sex and stress hormones, we examined the effect of a low perinatal BPA exposure on the function of the hypothalamic-pituitary-adrenal (HPA) axis at rest and upon application of acute stress. Throughout pregnancy and lactation rats received daily 40 µg BPA/kg body weight orally via cornflakes. We studied the effect of this low but chronic exposure to BPA in the male and female offspring at puberty. BPA exposure led to abnormal adrenal histology including reduced zona reticularis especially in male offspring, hyperplasia of zona fasciculata in both sexes, and increased adrenal weight in female offspring. BPA-treated females had increased basal corticosterone and reduced hypothalamic glucocorticoid receptors (GR) levels. Stressed BPA-exposed females exhibited anxiety-like behavioral coping, a less rigorous corticosterone response, and did not downregulate GR in the hypothalamus, compared with control females. BPA-exposed males exhibited a heightened corticosterone stress response compared with females; they also displayed increased pro-opiomelanocortin mRNA levels and retained the prestress levels of pituitary corticotropin-releasing hormone-receptor 1, compared with control males. We found that perinatal chronic exposure to a low dose of BPA perturbs the basal and stress-induced activity of the HPA axis in a sexually dimorphic manner at adolescence. Exposure to BPA might contribute to increased susceptibility to stress-related disorders in later life.