In vitro antimicrobial activity of daptomycin alone and in adjunction with either amoxicillin, cefotaxime or rifampicin against the main pathogens responsible for bacterial meningitis in adults

OBJECTIVES

As daptomycin adjunction is currently under clinical evaluation in the multicentre phase II AddaMAP study to improve the prognosis of pneumococcal meningitis, the present work aimed at evaluating the in vitro antimicrobial activity of daptomycin-based combinations against some of the most frequent species responsible for bacterial meningitis.

METHODS

Clinically relevant strains of Streptococcus pneumoniae, Listeria monocytogenes, Haemophilus influenzae and Neisseria meningitidis were obtained from National Reference Centers. The antimicrobial activity of amoxicillin, cefotaxime and rifampicin, either alone or in association with daptomycin, was explored through the determination of minimum inhibitory concentration (MIC) and fractional inhibitory concentration index (FICI) as well as time-kill assay (TKA) using the broth microdilution method.

RESULTS

All species taken together, the adjunction of daptomycin had no deleterious impact on the antimicrobial activity of amoxicillin, cefotaxime or rifampicin in vitro. Regarding Gram-positive bacteria, FICI and TKA analysis confirmed a global improvement of growth inhibition and bactericidal activity due to the adjunction of daptomycin. The synergistic effect prevailed for L. monocytogenes as demonstrated by FICI mainly <0.5 and a dynamic TKA-based synergy rate >50%. In addition, daptomycin-based associations did not modify the activity of β-lactam antibiotics or rifampicin against Gram-negative bacteria, notably N. meningitidis.

CONCLUSION

These results bring comforting evidence towards the clinical potential of daptomycin adjunction in the treatment of bacterial meningitis, which supports the ongoing AddaMAP clinical trial.

Activity of Different Antistaphylococcal Therapies, Alone or Combined, in a Rat Model of Methicillin-Resistant Staphylococcus epidermidis Osteitis without Implant

We developed a rat model of methicillin-resistant Staphylococcus epidermidis (MRSE) osteitis without implant to compare the efficacy of vancomycin, linezolid, daptomycin, ceftaroline, and rifampin either alone or in association with rifampin. A clinical strain of MRSE was inoculated into the proximal tibia. Following a 1-week infection period, rats received either no treatment or 3, 7, or 14 days of human-equivalent antibiotic regimen. Quantitative bone cultures were performed throughout the 14-day period. The mean ± SD quantity of staphylococci in the bone after a 1-week infection period was 4.5 ± 1.0 log10 CFU/g bone, with this bacterial load remaining stable after 3 weeks of infection (4.9 ± 1.4 log10 CFU/g bone). Vancomycin monotherapy was the most slowly bactericidal treatment, whereas ceftaroline monotherapy was the most rapidly bactericidal treatment. The addition of rifampin significantly increased the bacterial reduction for vancomycin, linezolid, and daptomycin. All tibias were sterilized after 2 weeks of treatment except for animals receiving vancomycin or daptomycin alone (66.6% and 50% of sterilization, respectively). These results show that ceftaroline and linezolid alone remain good options in the treatment of MRSE osteitis without implant. The combination with rifampin increases the antibiotic effect of vancomycin and daptomycin lines.

Kineret®/IL-1ra blocks the IL-1/IL-8 inflammatory cascade during recombinant Panton Valentine Leukocidin-triggered pneumonia but not during S. aureus infection

OBJECTIVES

Community-acquired Staphylococcus aureus necrotizing pneumonia is a life-threatening disease. Panton Valentine Leukocidin (PVL) has been associated with necrotizing pneumonia. PVL triggers inflammasome activation in human macrophages leading to IL-1β release. IL-1β activates lung epithelial cells to release IL-8. This study aimed to assess the relevance of this inflammatory cascade in vivo and to test the potential of an IL-1 receptor antagonist (IL-1Ra/Kineret) to decrease inflammation-mediated lung injury.

METHODS

We used the sequential instillation of Heat-killed S. aureus and PVL or S. aureus infection to trigger necrotizing pneumonia in rabbits. In these models, we investigated inflammation in the presence or absence of IL-1Ra/Kineret.

RESULTS

We demonstrated that the presence of PVL was associated with IL-1β and IL-8 release in the lung. During PVL-mediated sterile pneumonia, Kineret/IL-1Ra reduced IL-8 production indicating the relevance of the PVL/IL-1/IL-8 cascade in vivo and the potential of Kineret/IL-1Ra to reduce lung inflammation. However, Kineret/IL-1Ra was ineffective in blocking IL-8 production during infection with S. aureus. Furthermore, treatment with Kineret increased the bacterial burden in the lung.

CONCLUSIONS

Our data demonstrate PVL-dependent inflammasome activation during S.aureus pneumonia, indicate that IL-1 signaling controls bacterial burden in the lung and suggest that therapy aimed at targeting this pathway might be deleterious during pneumonia.

In vivo efficacy of ceftaroline fosamil in a methicillin-resistant panton-valentine leukocidin-producing Staphylococcus aureus rabbit pneumonia model

Ceftaroline, the active metabolite of the prodrug ceftaroline fosamil, is a cephalosporin with broad-spectrum in vitro activity against Gram-positive organisms, including methicillin-resistant Staphylococcus aureus (MRSA) and multidrug-resistant Streptococcus pneumoniae (MDRSP), and common Gram-negative pathogens. This study investigated the in vivo activity of ceftaroline fosamil compared with clindamycin, linezolid, and vancomycin in a severe pneumonia model due to MRSA-producing Panton-Valentine leukocidin (PVL). A USA300 PVL-positive clone was used to induce pneumonia in rabbits. Infected rabbits were randomly assigned to no treatment or simulated human-equivalent dosing with ceftaroline fosamil, clindamycin, linezolid, or vancomycin. Residual bacterial concentrations in the lungs and spleen were assessed after 48 h of treatment. PVL expression was measured using a specific enzyme-linked immunosorbent assay (ELISA). Ceftaroline, clindamycin, and linezolid considerably reduced mortality rates compared with the control, whereas vancomycin did not. Pulmonary and splenic bacterial titers and PVL concentrations were greatly reduced by ceftaroline, clindamycin, and linezolid. Ceftaroline, clindamycin, and linezolid were associated with reduced pulmonary tissue damage based on significantly lower macroscopic scores. Ceftaroline fosamil, clindamycin, and, to a lesser extent, linezolid were efficient in reducing bacterial titers in both the lungs and spleen and decreasing macroscopic scores and PVL production compared with the control.

Novel role of tissue transglutaminase (TG2) in chronic inflammatory diseases (48.12)

Tissue transglutaminase (TG2) has a critical role in the pathogenesis of chronic inflammatory diseases. We have previously described the key role of TG2 in cystic fibrosis (CF), a genetic disease characterised by chronic lung infections and inflammation. In CF, mutation on the CFTR gene results in an increased TG2 expression and activity leading to functional sequestration of the anti-inflammatory PPARγ and increase of inflammation.

Here we tested whether in vivo inhibition of TG2 can reverse inflammation in chronic inflammatory diseases. To assess the importance of TG2, we injected cystamine, a potent TG2 inhibitor, in a transgenic mouse model of CF and in the TAZ10 transgenic mice that spontaneously develop autoimmune thyroiditis.

Intraperitoneal administration of cystamine had a significant impact on the lung epithelium in the CF model, where it decreased TG expression and activity. The treatment was also able to dampen all the classic inflammatory parameters as well as restoring normal cellular levels of functional PPARγ. Interestingly, cystamine injections could also block inflammation in the TAZ10 TCR transgenic mouse model, highlighting the pivotal role of TG2 in generating inflammation in two very different pathologies.

This work underlines the critical role of TG2 in inflammation and provides new opportunities to develop therapeutic strategies for sufferers of chronic inflammatory diseases.

[I. Induced abortions and spontaneous abortions. Psychopathological aspects apropos of a preliminary sample of 411 requests for pregnancy interruption]

Since 1975 (17th January), abortion is free and legal in France. The authors analyse 411 first cases of women requiring for an abortion (seen over a period of 11 weeks). Most of them are young women, single, many begin their sexual life. Unwanted pregnancy indicates absence of contraception by ignorance, refusal or ambivalence (never used = 184 cases). 105 women used archaic and inefficient contraceptive means. Modern contraceptive means was used by 154 women but ill applied, ill tolerated and/or discarded (pill = 103 cases, I.U.D. = 14, diaphragme = 2, condoms = 35). Unwanted pregnancy and abortion signify failure of contraception. We compare psychologic and psychopathologic features of women requiring repeated induced abortion with those of women suffering of repeated spontaneous abortion and infertility. These women have frequently (same) problems of feminine identity, bad maternal imago, absence of father, unhappy, and conflictive childhood, immature sexuality and personnality. Contradiction between conscious and unconscious wishes create the two opposite situations and intrapsychic conflicts (spontaneous abortion = conscious willing of pregnancy + unconscious rejection of unbearable pregnancy; induced abortion = strong but unconscious wish of pregancy + conscious and volontary rejection of maternity). Psychotherapy should improve sexual and affective life and in both cases. The authors compare infanticide and abortion behaviors, contraceptive means, and psychological problems of doctors who are asked abortion.

[A religious sect, its mental ill patients, its physician and its psychiatrists]

A religious Sect (Jéhovah witness), its mental patients, its doctor and its psychiatrists. The authors study religious sects, specially Jéhovoah witness. Such 15 mentally ill patients among this group have been treated at the psychiatric clinic. The fact that they are members of a community, sharing the same religious faith, and having in common severe rules of life, is considered as having a pathogenic or beneficial effect. One of them, physician, explain their opinion of mental illness : they believe in biological factors and discard any psychotherapeutic mean.