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The objective of this study was to estimate the prevalence of methicillin-resistant Staphylococcus aureus (MRSA) in the production chain of dairy products. Of 367 tested samples (36 bulk tank milk (BTM), 19 dairy products, 72 human, 185 animal, 55 equipment), 212 (57.8%) were found positive for S. aureus . Almost all isolates (99.6%) were resistant to at least one antimicrobial and 13.3% were multi-drug resistant (MDR), exhibiting resistance to three or more antibiotic classes. Eleven samples (3%) were found contaminated by MRSA carrying the mec A gene. None of the MRSA isolates carried the mec C or the Pandon-Valentine leucocidin (PVL) genes. Four spa types were identified among the MRSA isolates: t127, t3586, t1773, t4038, with t127 being the most prevalent (7 out of 11). Two of them, t3586 and t1773, were isolated for the first time in Greece. Furthermore, Pulse-Field Gel Electrophoresis (PFGE) analysis indicated clonal circulation through the dairy production chain. The presence of MDR S. aureus , and especially MRSA, in animals and dairy products represents a potential threat for the spread of this pathogen in the community. The results indicated that human, animal and environmental sources could be involved in the contamination of dairy products along their production chain and therefore further investigation of contamination sources is needed to control the dispersion of MRSA in the community. [ABSTRACT FROM AUTHOR]

Abstract: Collybistin (Cb), a brain-specific guanine nucleotide exchange factor, has been shown to be essential for the gephyrin-dependent clustering of a specific set of GABAA receptors at inhibitory postsynaptic sites. Here, we examined whether the lack of Cb affects synaptic properties and neuronal activity in the intact hippocampus by monitoring network activity in the dentate gyrus of Cb-deficient mice after perforant-path stimulation in vivo. We found a decreased threshold for evoked population spikes of granule cells, indicating their increased excitability. Paired-pulse inhibition of the population spike, a measure for somatic GABAergic network inhibition, was enhanced. Mutant mice exhibited steeper slopes of field excitatory postsynaptic potentials, consistent with a reduced dendritic inhibition. In addition, the induction of long-term potentiation (LTP) was reduced. In line with these functional changes, the number of postsynaptic gephyrin and GABAA receptor clusters in the Cb-deficient dentate gyrus was significantly decreased. In conclusion, our data provide the first evidence that Cb-deficiency leads to significant changes of GABAergic inhibition, network excitability and synaptic plasticity in vivo. [Copyright &y& Elsevier]

Abstract: Collybistin (Cb) is a brain-specific guanine nucleotide exchange factor, which interacts with the inhibitory receptor anchoring protein gephyrin. In the hippocampus of constitutively Cb-deficient adult mice, gephyrin and gephyrin-dependent GABAA receptors (GABAARs) are lost from postsynaptic sites. Here, we used a Cre–loxP system to inactivate the Cb gene in the forebrain at different developmental stages. Deletion of Cb during embryonic development prevented gephyrin clustering during synaptogenesis and caused an accumulation of gephyrin aggregates in the cell body of CA1 pyramidal neurons. Inactivation of the Cb gene during the third postnatal week resulted in a protracted loss of postsynaptic gephyrin clusters and the appearance of cytoplasmic gephyrin aggregates. These changes in gephyrin distribution were accompanied by a similar reduction in synaptically localized GABAAR γ2-subunit immunoreactivity. Our data show that Cb is required for both the initial localization and maintenance of gephyrin and gephyrin-dependent GABAARs at inhibitory postsynaptic membrane specializations in the hippocampus. [Copyright &y& Elsevier]

Recently, there has been an increased tendency towards raw-milk consumption, which may pose a consumer risk, due to the possible presence of human pathogenic microorganisms, such as Staphylococcus aureus and even methicillin-resistant S. aureus (MRSA). The prevalence of S. aureus and methicillin-resistant S. aureus (MRSA) was investigated in 40 dairy (cattle, sheep and goat) farms in northern Greece. S. aureus and MRSA were detected in 47.8% and 4.1% of the 387 samples (raw milk, farmers and animal samples) tested, respectively. Most (81.3%) of the MRSA isolates harbored the mec A gene, whereas the mec C or Panton-Valentine Leucocidin (PVL) genes were not detected. Seven spa types were identified, with t127 being the most prevalent. Spa type t034 (CC398) was isolated for the first time from livestock in Greece. Staphylococcal enterotoxin genes were detected in 93.8% of the MRSA isolates. The MRSA isolates were genetically diverse and were all capable of biofilm production. Our results confirm the lurking threat of MRSA in raw milk and dairy farms and suggest the need for surveillance programs starting at the farm level. • Of 387 samples tested, 185 (47.8%) were S. aureus -positive & 16 (4.1%) MRSA-positive. • Most MRSA isolates (6/16) belonged to spa type t127. • Our study is the first to report MRSA CC398 in goats in Greece. • 93.8% of MRSA isolates harbored SE-genes; sec being most frequent (15/16). • All MRSA isolates were capable to form biofilm. [ABSTRACT FROM AUTHOR]