Staphylococcus Aureus Carriage in French Athletes at Risk of CA-MRSA Infection: a Prospective, Cross-sectional Study.

BACKGROUND: Staphylococcus aureus (SA) is a leading cause of infectious diseases in sports teams. In recent decades, community-associated SA (CA-SA) strains have emerged worldwide and have been responsible for outbreaks in sports teams. There are very few data on the prevalence of these strains in France, and none on the carriage among athletes. METHODS: We conducted a cross-sectional study to determine the SA carriage proportion among athletes practicing sports at risk for CA-SA infection in a French county, and determined the methicillin-resistant and/or CA-SA proportion. We also analyzed SA carriage according to risks factors and studied the SA clonality in a sample of our population. RESULTS: We included 300 athletes; SA carriage proportion was 61% (n = 183) and one was MRSA carrier (0.33%). The MRSA strain belonged to the clonal complex ST5. None of the strain produced Panton Valentine Leucocidin, and we did not find clonal distribution within the teams. Interestingly, we found a high throat-only carriage (n = 57), 31.1% of the SA carriers. CONCLUSION: We found a high SA carriage with a local epidemiology quite different than that reported in a similar population in the USA. Further studies on SA carriage should include throat sampling. TRIAL REGISTRATION: The approved protocol was registered on ClinicalTrial.gov , NCT01148485.

Lindane differently modulates intracellular calcium levels in two populations of rainbow trout (Oncorhynchus mykiss) immune cells: head kidney phagocytes and peripheral blood leucocytes.

We studied the in vitro effects of high concentrations of the insecticide lindane (from 2.5 to 100 microM) on intracellular calcium levels ([Ca(2+)](i)) in rainbow trout head kidney phagocytes and peripheral blood leucocytes (PBLs). [Ca(2+)](i) was measured during 6 min by spectrofluorimetry using Indo-1/AM as fluorescent probe. Lindane, from 5 to 100 microM, increased [Ca(2+)](i) in PBLs and from 25 microM in phagocytes. In Ca(2+)-free medium, only 50 and 100 microM lindane increased significantly [Ca(2+)](i) in PBLs and only 100 microM lindane in phagocytes. However, lindane at 5 and 10 microM, induced a decrease in [Ca(2+)](i) in phagocytes suspended in Ca(2+)-free medium. Lindane needed extracellular calcium to rise [Ca(2+)](i) in phagocytes but not in PBLs. Lindane effects on endoplasmic reticulum (ER) calcium store was examined. In spite of mobilisation by lindane of ER calcium store in phagocytes, it had an opposite effect in PBLs. The composition of the two cell population can explain the differences in calcium modulation observed. [Ca(2+)](i) is an extremely important signal transduction element in physiology and modulation of [Ca(2+)](i) by lindane can be responsible for modulations of immune cell functions. Moreover, sustained rises in [Ca(2+)](i) as observed in our study may be associated with cell death and explained partially the cytotoxicity of this organochlorine insecticide on fish immune cells.

3-Methylcholanthrene induces lymphocyte and phagocyte apoptosis in common carp (Cyprinus carpio L) in vitro.

Polycyclic aromatic hydrocarbons (PAH) are an important class of environmental pollutant that are known to be carcinogenic and immunotoxic. In mammals it was suggested that PAH compromise the immune system in part through the induction of programed cell death (apoptosis). In fish, no study has reported the importance of this physiological process in PAH-induced immunotoxicity. We have therefore investigated the capacity of 3-methylcholanthrene to induce lymphocyte and phagocyte apoptosis in carp. By three criteria (exposition of phosphatidylserine at the outer cell membrane, chromatin condensation and fragmentation, and decreased cell size) the data indicate that 3-methylcholanthrene (3-MC) treatment (from 20 to 200 microM) during 24 h produces apoptosis in both lymphocytes and phagocytes. In order to evaluate whether 3-MC induced apoptosis is related to the metabolic activation of 3-MC or 3-MC Ah-R binding, co-exposure experiments with 3-MC and alpha-naphtoflavone (alpha-NF), a compound that inhibits metabolic activation of 3-MC and 3-MC Ah-R binding were performed. While alpha-NF did not prevent 3-MC-induced apoptosis, the compound itself was found to be a strong inducer of apoptosis. There results might indicate that metabolic activation of 3-MC or 3-MC Ah-R binding is not causally linked to apoptosis. However, since 3-MC, alpha-NF and 3-MC + alpha-NF treatments produce the same sustained increase (3 h minimum) in intracellular calcium level, it is possible that this phenomenon is implicated in the induction of programmed cell death by these hydrocarbons.

3-methylcholanthrene inhibits lymphocyte proliferation and increases intracellular calcium levels in common carp (Cyprinus carpio L).

Polycyclic aromatic hydrocarbons (PAHs) are an important class of environmental pollutants that are known to be carcinogenic and immunotoxic. Many authors have focused on macrophage activities in fish exposed to PAHs. However, fewer studies have reported decrease in specific immunity in such fish. We investigated the intracellular mechanisms by which the 3-methylcholanthrene (3-MC) decreased lymphocyte proliferation in carp. T- and B-lymphocyte proliferation induced by Concanavalin A (Con A) and lipopolysaccharide (LPS) were inhibited by 3-MC (0.5-50 microM). 3-MC also produced a rapid and a sustained increase in intracellular calcium concentration ([Ca(2+)](i)) (2 h minimum). However, the cytochrome p450 1A and Ah receptor inhibitor, alpha-naphtoflavone (a-NF), also inhibited lymphocyte proliferation and did not reverse the effects of 3-MC. Moreover, since a-NF and 3-MC increased [Ca(2+)](i) and inhibited lymphocyte proliferation it was possible that calcium release played a role in 3-MC-inhibited lymphocyte proliferation. The rise in [Ca(2+)](i) induced by 3-MC was potentiated by the inhibitor of the endoplasmic reticulum calcium ATPases, thapsigargin. Treating cells with 3-MC decreased calcium mobilization caused by thapsigargin. These results suggest that 3-MC acts on the endoplasmic reticulum, perhaps directly on calcium ATPases, to increase intracellular calcium levels in carp leucocytes.

Lindane-induced macrophage activating factor (MAF) production by peripheral blood leukocytes (PBLs) of rainbow trout (Oncorhynchus mykiss): involvement of intracellular cAMP mobilization.

We studied the in vitro effects of the insecticide lindane (2.5-50 microM) on macrophage activating factor (MAF) production by the peripheral blood leukocytes (PBLs) in rainbow trout. The MAF production induced by the mitogens concanavalin A (ConA) and phorbol-12-myristate-13-acetate (PMA) was not modified by lindane pre-treatment. But lindane alone (2.5-25 microM) stimulated the secretion of MAF by PBLs. Intracellular calcium levels ([Ca2+]i) was measured over 6 min by spectrofluorimetry using Indo-1/AM as fluorescent probe. Lindane (25-100 microM) significantly increased the [Ca2+]i in PBLs, but had no effect on calcium at the dose that caused MAF secretion. Moreover, the effect of lindane on MAF production was potentiated by the inhibitor of phosphodiesterase, isobutylmethylxanthin (IBMX). Lindane also directly increased adenosine monophosphate cyclic (cAMP) in PBLs over the same concentration range that it stimulated MAF production by PBLs. Taken together, these results suggest that lindane increase MAF production by acting on intracellular cAMP concentrations. Moreover, the capacity of this insecticide to act on the [Ca2+]i or on the intracellular concentrations of cAMP according to the dose used could possibly explain its contradictory effects earlier observed on immunity.

3-Methylcholanthrene increases phorbol 12-myristate 13-acetate-induced respiratory burst activity and intracellular calcium levels in common carp (Cyprinus carpio L) macrophages.

Phagocytic cells play a key role in the fish immune system. They secrete reactive oxygen species (ROS) involved in their bactericidal activity. These cells are highly sensitive to pollution by polycyclic aromatic hydrocarbons and other organic pollutants. We have investigated the intracellular mechanisms by which 3-methylcholanthrene (3-MC) increased bactericidal activity of carp phagocytes. Macrophages isolated from head kidney (pronephros) and incubated 1 h with 3-MC enhanced their production of ROS when they were stimulated 1.25 h with phorbol 12-myristate 13-acetate (PMA), a direct activator of protein kinase C (PKC). 3-MC also produced a rapid and a sustained increase in [Ca(2+)](i) (2 h minimum). However, the cytochrome P450 1A and Ah receptor inhibitor, alpha-naphtoflavone (alpha-NF), inhibited the potentiation of PMA-induced ROS production, suggesting 3-MC metabolic activation. Moreover, alpha-NF increased [Ca(2+)](i) without macrophage ROS production, suggesting that some mechanism other than calcium release is playing a role in the stimulation of the macrophages by 3-MC. The rise in [Ca(2+)](i) induced by 3-MC was potentiated by the inhibitor of the endoplasmic reticulum calcium ATPases, thapsigargin. And treating the cells with 3-MC decreased the calcium mobilization caused by thapsigargin. These results suggest that 3-MC acts on the endoplasmic reticulum, perhaps directly on calcium ATPases, to increase intracellular calcium levels in carp phagocytes.

Lindane increases macrophage-activating factor production and intracellular calcium in rainbow trout (Oncorhynchus mykiss) leukocytes.

The authors studied the in vitro effects of lindane on macrophage-activating factor (MAF) production by peripheral blood leukocytes (PBLs) in rainbow trout. MAF production by PBLs induced normally by mitogens concanavalin A (ConA) and phorbol myristate acetate (PMA) was not modified by a pretreatment with lindane (from 2.5 to 50 microM). Only a concentration of 100 microM lindane decreased MAF production, associated with cellular death. Moreover, MAF activities were detected in supernatants of PBL cultures treated with lindane from 2.5 to 10 microM in absence of ConA/PMA stimulation. Factors present in these supernatants remain to be identified. Lindane, at concentrations which did not induce MAF production (50 and 100 microM) led to an increase in PBL calcium levels by acting on the endoplasmic reticulum calcium stores. Although the intracytosolic calcium concentration ([Ca(2+)](i)) increase seems to be associated with cell death, lindane-induced MAF production may be linked with other intracellular mechanisms.

Lindane increases in vitro respiratory burst activity and intracellular calcium levels in rainbow trout (Oncorhynchus mykiss) head kidney phagocytes.

Phagocytic cells are the main actors of the fish immune system. They secrete reactive oxygen species (ROS) involved in their bactericidal activity. The effects of lindane on ROS production in rainbow trout phagocytes are contradictory. Here, we study the effects of high concentrations of lindane on ROS production (by chemiluminescence) and on intracellular calcium levels ([Ca(2+)](i)) (by spectrofluorimetry) in trout phagocytes. In these cells, lindane from 2.5 to 10 µM, increases ROS production and has no effect on [Ca(2+)](i). From 25 to 200 µM, lindane leads to a rise in ROS production (maximal value measured: 41152+/-6253 RLU for 100 µM lindane) associated with an increase in [Ca(2+)](i) (+3149+/-96 nM for 100 µM lindane) and with cytotoxicity which appears 2 min after addition of 100 µM lindane (25.4+/-3.75%; P<0.05). In the absence of extracellular calcium, ROS production of lindane-treated cells remains significantly higher than in controls (maximal value measured: 1899+/-254 RLU for 25 µM lindane), a significant decrease in [Ca(2+)](i) is observed in cells treated with 5 or 10 µM lindane (-54+/-35 nM for 10 µM lindane), and an increase in [Ca(2+)](i) in cells treated with 100 µM lindane (330+/-33 nM). The rise in [Ca(2+)](i) induced by lindane is inhibited when cells are preincubated with thapsigargin (Thaps). We conclude that lindane induces an increase in [Ca(2+)](i)50 µM) alter Ca(2+) homeostasis in the absence of extracellular Ca(2+), confirming that lindane can affect other intracellular stores of Ca(2+). At low concentrations (<25 µM), lindane stimulates ROS production by Ca(2+)-independant mechanisms without inducing cytotoxicity. From 25 µM, lindane increases [Ca(2+)](i) and maximal cytotoxicity appears from 100 µM lindane. Lindane toxicity in fish phagocytes may be associated with high [Ca(2+)](i) and high ROS production. Thus, ROS are beneficial in protection of the organism but when ROS are produced in excess, they can be toxic for cells and tissues.

The effects of 3-methylcholanthrene on macrophage respiratory burst and biotransformation activities in the common carp (Cyprinus carpio L.).

The sensitivity of phagocytic cell function as a bioindicator of pollution stress by polycyclic aromatic hydrocarbons was evaluated in the common carp (Cyprinus carpio L). The time course response of the head-kidney macrophage respiratory burst was measured 1, 2, 3, 5 and 7 days after intraperitoneal injection of a prototypical Cyp 1A inducer (3-methylcholanthrene). This immune activity was compared to the rate of induction of total cytochrome P450, ethoxyresorufin O-deethylase activity (EROD) and glutathione S-transferase activity (GST) in the liver and head-kidney. 3-methylcholanthrene (40 mg kg(-1)) caused a rapid increase in the macrophage respiratory burst. This response was maximal at day 3 post exposure and coincided with maximum induction of cytochrome P450 and EROD activity in liver and head-kidney. Moreover, alpha-naphtoflavone, which functions as both an Ah receptor antagonist and an inhibitor of cytochrome P450 1A activity, reversed the 3-methylcholanthrene induction of immune and enzymatic parameters measured, suggesting metabolic processes. Taken together these results suggest that the induction of macrophage oxidative function may be an equally sensitive marker of exposure to polycyclic aromatic hydrocarbon as the induction of biotransformation activities and confirm that responses mediated by the Ah receptor are similar, if not identical, to those of mammals.