[Respiratory infections: Additional transmission-based precautions in healthcare facilities]. / Les infections respiratoires : prévention de la transmission en milieu de soins.

INTRODUCTION: In health care, measures against cross-transmission of microorganisms are codified by standard precautions, and if necessary, they are supplemented by additional precautions. STATE OF THE ART: Several factors impact transmission of microorganisms via the respiratory route: size and quantity of the emitted particles, environmental conditions, nature and pathogenicity of the microorganisms, and degree of host receptivity. While some microorganisms necessitate additional airborne or droplet precautions, others do not. PROSPECTS: For most microorganisms, transmission patterns are well-understood and transmission-based precautions are well-established. For others, measures to prevent cross-transmission in healthcare facilities remain under discussion. CONCLUSIONS: Standard precautions are essential to the prevention of microorganism transmission. Understanding of the modalities of microorganism transmission is essential to implementation of additional transmission-based precautions, particularly in view of opting for appropriate respiratory protection.

Nosocomial outbreak of Pseudomonas aeruginosa associated with a drinking water fountain.

Over a four-month period, ten patients were suspected of having acquired nosocomial infection to P. aeruginosa in the ear, nose, and throat department. Environmental and clinical isolates were compared. Only water from a drinking water fountain was contaminated by P. aeruginosa. This isolate and those of three patients had indistinguishable random amplified polymorphic DNA profiles. These patients had serious oncology diseases. The drinking water fountain was used for their alimentation by percutaneous endoscopic gastrostomy and was the origin of the outbreak. Another type of drinking fountain with a terminal ultraviolet treatment was installed, following which no new infections linked to drinking water were identified.

Control of multi-drug-resistant Acinetobacter baumannii outbreaks in an intensive care unit: feasibility and economic impact of rapid unit closure.

From January to May 2006, a nosocomial outbreak caused by a multi-drug-resistant strain of Acinetobacter baumannii (MDRAB) occurred in a multi-specialty surgical ICU (SICU). During this episode, 20 patients were colonized by an identical MDRAB strain. Despite introduction of control measures, the outbreak was only stopped after complete closure of the unit. When a second MDRAB outbreak was confirmed in the same unit in January 2009, the SICU was closed as soon as possible. This measure allowed faster control of the outbreak, which only involved seven patients and lasted for 25 days. The economic impact of the outbreak was also considerably lower; estimated costs were €202,214 in 2009 compared with €539,325 in 2006. This study found that rapid closure of the SICU, with patients cohorted elsewhere, was a cost-effective way of controlling an MDRAB outbreak.

A mimic of HIV-1 nucleocapsid protein impairs reverse transcription and displays antiviral activity.

Combined inhibition of HIV-1 reverse transcriptase and protease has significantly improved the treatment of AIDS. Nevertheless, resistance to these drugs occurs rapidly because of viral mutations, emphasizing the importance of identifying novel retroviral targets to develop new drug combinations. The critical role played by the nucleocapsid protein NCp7 of HIV-1 at different steps of the retrovirus life cycle makes it an attractive target for the development of new antiviral agents. NCp7 contains two highly conserved zinc fingers and is characterized by a three-dimensional structure that cannot be modified without a complete loss of infectivity of mutated viruses. Based on these structural data, we report that RB 2121, a cyclic peptide designed to mimic several essential biological determinants of NCp7, displays antiviral activity by inhibiting HIV-1 replication in CEM-4 cells infected by HIV-1. In vitro, RB 2121 does not interfere with HIV-1 cell entry and viral enzymes but is able to inhibit the annealing activities of NCp7 by recognizing nucleic acids. Analysis of proviral DNA synthesis by means of PCR has shown that RB 2121 acts at an early step of the retrovirus life cycle by inducing a dose-dependent reduction in transcribed DNA levels through inhibition of NCp7-reverse transcriptase interaction. Because of its original mechanism of action, RB 2121 provides an interesting lead for the rational development of new anti-HIV-1 agents that could be associated advantageously with enzyme inhibitors to counteract rapid virus mutations and resistance problems observed in tritherapies.

Betulinic acid derivatives: a new class of human immunodeficiency virus type 1 specific inhibitors with a new mode of action.

A series of omega-undecanoic amides of lup-20(29)-en-28-oic acid derivatives were synthesized and evaluated for activity in CEM 4 and MT-4 cell cultures against human immunodeficiency virus type 1 (HIV-1) strain IIIB/LAI. The potent HIV inhibitors which emerged, compounds 5a, 16a, and 17b, were all derivatives of betulinic acid (3beta-hydroxylup-20(29)-en-28-oic acid). No activity was found against HIV-2 strain ROD. Compound 5a showed no inhibition of HIV-1 reverse transcriptase activity with poly(C).oligo(dG) as template/primer, nor did it inhibit HIV-1 protease. Additional mechanistic studies revealed that this class of compounds interfere with HIV-1 entry in the cells at a postbinding step.

Betulinic acid derivatives: a new class of specific inhibitors of human immunodeficiency virus type 1 entry.

A novel series of omega-aminoalkanoic acid derivatives of betulinic acid were synthesized and evaluated for their activity against human immunodeficiency virus (HIV). The anti-HIV-1 activity of several members of this new series was found to be in the nanomolar range in CEM 4 and MT-4 cell cultures. The optimization of the omega-aminoalkanoic acid side chain is described. The presence of an amide function within the side chain was found important for optimal activity. RPR 103611 (14g), a statine derivative, was found to be inactive against HIV-1 protease, reverse transcriptase, and integrase as well as on gp120/CD4 binding. "Time of addition" experiments suggested interaction with an early step of HIV-1 replication. As syncytium formation, but not virus-cell binding, seems to be affected, betulinic acid derivatives are assumed to interact with the postbinding virus-cell fusion process.

Polyanion inhibitors of human immunodeficiency virus and other viruses. 1. Polymerized anionic surfactants.

A series of polyanionic compounds was synthesized and evaluated for their activity against human immunodeficiency virus (HIV-1, HIV-2) and various other RNA and DNA viruses. Several compounds, i.e., 2p, 3p, 8p, 13p, 14p, 15p, 17p, 18p, and 19p, proved active against HIV-1 within the concentration range of 0.1-3 micrograms/mL while not being toxic to the host cells (CEM, MT-4) at concentrations up to 100 micrograms/mL or higher. As a rule, these polyanionic compounds proved also active, albeit at somewhat higher concentrations than those required for HIV-1 inhibition, against a number of other enveloped viruses, including HIV-2, human cytomegalovirus, influenza A virus, respiratory syncytial virus, and arenaviruses (Junin and Tacaribe). Among the most potent HIV-1 inhibitors ranked compounds 18p and 19p, the sodium salts of N-methylamides obtained by polymerization of monomers prepared starting from 10-undecenoyl chloride and omega-aminoalkanoic acids.

Prevention of HIV coat protein (gp120) toxicity in cortical cell cultures by riluzole.

Neurological complications observed in HIV-infected patients are very frequent. Neocortical lesions include reduced neuronal density due to neuronal degeneration. The HIV envelope protein gp120 has potent neurotoxic properties in cell cultures blocked either by NMDA antagonists or calcium channel antagonists. Moreover, human monocytoid cell lines infected by HIV release endogenous toxic factors with comparable cellular actions. We have analysed the effects of riluzole, a compound reducing the excitatory amino acid release on gp120-induced neurotoxicity in primary neuronal cultures. Riluzole, which blocks the release of glutamate and aspartate from nerve terminals, prevents (10(-7) M) the neuronal degeneration produced by 20 pM of gp120 in cortical cell cultures. This result could suggest that toxic factors produced by activated macrophages might increase glutamate release, and that this may be prevented by riluzole.

Infection of human macrophages with an endogenous tumour necrosis factor-alpha (TNF-alpha)-independent human immunodeficiency virus type 1 isolate is unresponsive to the TNF-alpha synthesis inhibitor RP 55778.

Monocyte-derived macrophages (MDM) were demonstrated to be susceptible to productive infection by the monocytotropic human immunodeficiency virus type 1 (HIV-1) strain HIV-1/Ba-L and by three primary HIV-1 isolates, HIV-1/DAS, HIV-1/PAR and HIV-1/THI. Production of tumour necrosis factor-alpha (TNF-alpha), interleukin-6 (IL-6) and IL-1 beta was monitored between days 3 and 26 after MDM infection. TNF-alpha and IL-6 were detected in cell culture supernatants from days 16 to 21 following HIV-1/DAS, HIV-1/PAR and HIV-1/Ba-L infection, at the time of high viral replication. IL-1 beta was not found at the same time points. TNF-alpha mRNA expression occurred around the peak of both TNF-alpha levels and supernatant RT activities. In HIV-1/THI-infected macrophage cultures no endogenously produced TNF-alpha was observed, despite high levels of HIV-1 in MDM. This result demonstrates that a primary isolate may replicate independently of TNF-alpha in MDM. To investigate the relationship between TNF-alpha and viral replication we used a TNF-alpha synthesis inhibitor, RP 55778. Treatment throughout the course of cell culture resulted in a significant decrease in both TNF-alpha levels and viral production in HIV-1/DAS-, HIV-1/PAR- and HIV-1/Ba-L-infected MDM cultures. This phenomenon is reversed by adding recombinant human TNF-alpha to the RP 55778-treated cell cultures from day 14 post-infection. No effect of RP 55778 was observed in MDM cultures infected with the primary isolate HIV-1/THI, whose replication is independent of TNF-alpha production and therefore remained unchanged after RP 55778 treatment. We conclude that the clinical value of such a drug is directly dependent on the ability of the HIV-1 strains involved to induce TNF-alpha production at the time of viral replication.

Treatment of human monocyte-derived macrophages with a TNF alpha synthesis inhibitor prior to HIV1 infection: consequences on cytokine production and viral replication.

Human monocyte-derived macrophages (MDM) were infected with the viral strain HIV1/Ba-L and with the clinical isolates HIV1/DAS and HIV1/PAR. Kinetics of tumour necrosis factor alpha (TNF alpha) and interleukin-6 (IL6) production were investigated for 28 days after infection. At the early stages of infection we observed significant TNF alpha and IL6 secretion 2 to 10 h after infection, whatever the viral strain we used. During the late events of MDM infection, TNF alpha and IL6 were detected over 16 to 21 days following HIV1 infection, at the time of high viral replication. Pretreatment of MDM with a TNF alpha synthesis inhibitor, RP 55778, 4 h prior to HIV infection induced a modified cytokine pattern during the first ten hours of infection: TNF alpha production was totally inhibited despite comparable amounts of IL6. At the late phases of the cell culture, a decrease in magnitude of both viral and cytokine production as well as a delay in the appearance of reverse transcriptase activity and cytokine secretion peaks were observed in RP-55778-pretreated and HIV1-infected MDM cultures. Similar results were obtained after pretreatment of HIV1/DAS-infected MDM cultures with an anti-TNF alpha monoclonal antibody.

Triterpene derivatives that block entry of human immunodeficiency virus type 1 into cells.

A series of triterpene compounds characterized by a stringent structure-activity relationship were identified as potent and selective inhibitors of human immunodeficiency virus type 1 (HIV-1) replication. Currently studied botulinic derivatives have 50% inhibitory concentrations (IC50) against HIV-1 strain IIIB/LAI in the 10 nM range in several cellular infection assays but are inactive against HIV-2. These compounds did not significantly inhibit the in vitro activities of several purified HIV-1 enzymes. Rather, they appeared to block virus infection at a postbinding, envelope-dependent step involved in the fusion of the virus to the cell membrane.

A platelet-activating factor antagonist, RP 55778, inhibits cytokine-dependent induction of human immunodeficiency virus expression in chronically infected promonocytic cells.

A platelet-activating factor antagonist, RP 55778, potently suppressed the induction of human immunodeficiency virus (HIV) expression in chronically infected promonocytic U1 cells. RP 55778 inhibited the production of reverse transcriptase activity in U1 cells stimulated with the transcriptionally active inducers of virus production, tumor necrosis factor alpha and phorbol 12-myristate 13-acetate. This effect was correlated only in part with a reduction in the levels of HIV RNA, suggesting that this agent was also affecting posttranscriptional levels of virus production. In this regard, RP 55778 effectively blocked the induction of HIV expression in U1 cells stimulated with interleukin 6 and granulocyte-macrophage colony-stimulating factor, which act predominantly as posttranscriptional activators of HIV expression. Finally, RP 55778 inhibited the production of endogenous tumor necrosis factor alpha in phorbol 12-myristate 13-acetate-stimulated cells, thereby interfering with an autocrine pathway of virus expression. The suppressive effects of RP 55778 on HIV expression appeared to be independent of the platelet-activating factor cell surface receptor on U1 cells. RP 55778 inhibited acute HIV replication in primary T-cell blasts and the proliferative capacity of these cells. This study suggests that RP 55778 may represent potentially useful compounds in the treatment of HIV infection.

Radioprotective effects of the immunostimulating lauroylpeptide LtriP (RP 56142).

The lipopeptide lauroyl-L-Ala-gamma-D-Glu-L,L-A2pm (LtriP) increased the resistance of mice to the lethal effect of gamma-ray irradiation. The radioprotective effect was dependent on the doses of LtriP and of radiation. Maximum survival was observed when the lipopeptide was injected on two successive days before irradiation. This activity seems to be related to immunostimulating functions, since the non-immunostimulating analog lauroyl-L-Ala-gamma-D-Glu-D,D-A2pm-Gly, containing D,D-diaminopimelic acid, was not radioprotective. The protective activity might result from an induction of cytokines, such as IL-1, TNF and M-CSF, since LtriP induced the mRNA expression and the secretion of these immunomodulators.

RP 54745, a potential antirheumatic compound. I. Inhibitor of macrophage stimulation and interleukin-1 production.

RP 54745 is an amino-dithiole-one compound found to be active at micromolar concentration on the metabolism of stimulated macrophages, for example, the hexose monophosphate pathway (HMP) and the exocytosis of lysosomal enzymes. LPS-induced interleukin-1 (IL-1) production by murine peritoneal macrophages was also diminished by this compound in vitro as well as in vivo. This effect was confirmed at the mRNA level; at the concentration of 3 x 10(-6) M, the IL-1 alpha and beta mRNA signals were inhibited, whereas the TNF alpha mRNA signal was only slightly lessened. These observations were confirmed in vivo, with a dose of RP 54745 of 25 mg kg-1. These results led us to consider that RP 54745 might influence certain cells and cytokines implicated in the regulation of the immune system, the disfunctioning of which can lead to inflammatory disorders or autoimmune pathologies.

RP 54745, a potential antirheumatic compound. II. In vivo properties in different animal models.

The results obtained with RP 54745, an amino-dithiole-one compound, on stimulated macrophages, revealing inhibition of the hexose monophosphate pathway (HMP), of the exocytosis of lysosomal enzymes and of the production of interleukin-1 (IL-1), by the compound in vitro as well as in vivo, suggested that RP 5475 might influence cells and cytokines implicated in the regulation of the immune system, the disfunctioning of which can lead to inflammatory disorders or autoimmune pathologies. RP 54745 was effective at moderate oral doses (around 5 mg kg-1) in different mouse models of induced arthritis and in the MRL/lpr mice, genetically predisposed to develop an autoimmune pathology including arthritic disorders. The clinical status of the MRL mice, and several of their disturbed biochemical and immunological parameters, improved after a 3-month treatment with RP 54745. This activity of RP 54745 makes it a very attractive antirheumatic compound and a potentially effective treatment in pathologies where IL-1 production is exacerbated.

An exon 5-deleted mRNA encodes a functional interleukin 2 receptor alpha-subunit.

Two polypeptides are involved in interleukin 2 binding: a low-affinity receptor of 55 kD (IL2-R alpha) and an intermediate affinity component of 75 kD (IL2-R beta). We describe the cloning by the Polymerase Chain Reaction of the coding region of IL2-R alpha from a human T-cell lymphoma cell line. One clone presented a 72-bp deletion that precisely corresponds to exon 5. The deleted form and the normal IL2-R alpha cDNA were expressed CHO cells. Stable transfected cellular clones were compared for their immunoreactivity to monoclonal antibodies directed against IL2-R alpha and for their ability to bind radiolabeled IL2. The presence or absence of the protein region encoded by exon 5 did not modify the IL2-binding capacity of the receptor.

Acute effects of tumor necrosis factor on the microcirculation in rat cremaster muscle.

The acute effects of TNF on the microcirculation were studied by in vivo microscopy in rat cremaster muscle. The changes in arteriolar diameter after topical administration of recombinant TNF (rTNF; 10(-4)-10(4) ng/ml) were studied in second-, third-, and fourth-order arterioles (A2-A4) whose mean diameters under control conditions were 64.3, 30.7, and 14.8 microns respectively. rTNF induced a concentration-dependent vasodilation whose amplitude was largest for the smallest arterioles. At the highest concentration tested, arteriolar diameter increased by 21, 29, and 41% of control diameter for the A2, A3, and A4 arterioles, respectively. Indomethacin or mefenamic acid, two structurally different prostaglandin synthesis inhibitors, markedly inhibited the degree of vasodilation induced by rTNF in the three arteriolar orders. As regards the effect of rTNF on vasoconstriction in response to norepinephrine, vasoconstriction was greatest for the smallest arterioles, and did not change 10 min after rTNF administration for any of the three arteriolar orders. We conclude that (a) rTNF has a direct vasodilatory effect which is greatest in the smallest arterioles, (b) this vasodilation is at least partly mediated by prostaglandins, and (c) administration of rTNF in itself does not acutely alter the response of the arterioles to vasopressive drugs.

Modulation of interleukin-1 and tumor necrosis factor expression by beta-adrenergic agonists in mouse ameboid microglial cells.

Brain macrophages (ameboid microglial cells) purified to homogeneity and cultured in vitro synthesize and release IL-1 and TNF upon stimulation with lipopolysaccharide (LPS). This induction can be measured at the levels of transcription and translation. In the present study we have analysed whether certain compounds normally present in the nervous tissue could regulate cytokine production by brain macrophages. We demonstrate that the beta-adrenergic agonist isoproterenol, at a concentration of 10(-7) M; inhibits the LPS-induced transcription and release of TNF alpha. At the same concentration, isoproterenol increases the accumulation of IL-1 alpha and IL-1 beta mRNAs. In spite of its strong effect on IL-1 mRNA accumulation, the adrenergic agonist did not enhance IL-1 activity produced by microglial cells. On the contrary, as is the case for TNF, the LPS-induced production of IL-1 was inhibited by isoproterenol. The effects of isoproterenol on cytokine production specifically involve the beta 2 and not the beta 1 adrenergic receptor. It thus appears (i) that the accumulation of mRNAs coding for TNF alpha on one hand and IL-1 alpha and beta on the other is regulated in two opposite ways by the stimulation of the beta 2-adrenergic receptor and (ii) that mRNA accumulation and cytokine production and secretion are not necessarily coupled.

[Cachectin or TNF (tumor necrosis factor): clinical implications]. / Cachectine ou TNF (tumor necrosis factor): implications cliniques.

Septic shock remains an acute condition with a bad prognosis and a high mortality rate. This could be related to our incomplete understanding of the pathophysiological mechanisms involved, especially in the immunological field. Recently, several studies have stressed the key role of cytokines. Amongst these, the tumour necrosis factor (TNF) seems to be the most important. This peptide is a hormone secreted by monocytes and macrophages under the effect of various stimuli such as lipopolysaccharides or endotoxin. Giving TNF mimicks the clinical and biological patterns of septic shock. Moreover, high concentrations of TNF have been found in patients suffering from septic shock. Pretreatment with monoclonal antibodies against TNF prevents the occurrence of septic shock after endotoxin administration. TNF acts directly via ubiquitous specific receptors; this probably explains its diffuse activity. The therapeutic implications of these recent advances are not clear. It is not known, for the moment, whether TNF secretion is beneficial or deleterious for the patient.

RP 55778, a PAF receptor antagonist, prevents and reverses LPS-induced hemoconcentration and TNF release.

Platelet-activating factor (PAF) and tumor necrosis factor (TNF) are present in the plasma of animals injected with endotoxin (LPS). Furthermore, when exogenously administered to animals, PAF and TNF induce similar pathological effects. Thus, in order to explore a possible link between these two factors, the effects of a PAF receptor antagonist, RP 55778, and a glucocorticoid, dexamethasone, were studied on LPS-induced hemoconcentration in rats and on the release of TNF induced by exposing isolated murine macrophages to LPS. RP55778 administered either before or after LPS inhibited these endotoxin effects whereas dexamethasone was effective only when given prior to the LPS challenge. Additionally, in murine macrophages the strong TNF mRNA signal induced by LPS was abolished by RP 55778 and dexamethasone treatment. These results indicate that PAF and TNF can mediate the functional manifestations associated with endotoxemia and only RP 55778 appears to show potential for activity against an already established LPS response.