Mycobacterium tuberculosis Beijing type mutation frequency--author's response.

Contains fulltext : 125696.pdf (publisher's version ) (Open Access)1 maart 201

SILA-421 activity in vitro against rifampicin-susceptible and rifampicin-resistant Mycobacterium tuberculosis, and in vivo in a murine tuberculosis model

Item does not contain fulltextDue to the emergence of multidrug-resistant and extensively drug-resistant tuberculosis (TB), there is an urgent need for new TB drugs or for compounds that improve the efficacy of currently used drugs. In this study, time-kill kinetics of SILA-421 as a single drug and in combination with isoniazid (INH), rifampicin (RIF), moxifloxacin (MXF) or amikacin (AMK) against Mycobacterium tuberculosis were assessed. Therapeutic efficacy in vivo in a mouse TB model was also studied. Further in vitro analysis was performed with a RIF-susceptible and RIF-resistant strains of M. tuberculosis. When used as a single drug, SILA-421 in vitro showed concentration-dependent and time-dependent bactericidal activity. SILA-421 also enhanced the activity of INH and RIF, resulting in synergy in the case of INH. Emergence of INH resistance following exposure to INH can be prevented by the addition SILA-421. SILA-421 had no additional value in combination with MXF or AMK. Furthermore, SILA-421 enhanced the activity of RIF towards a RIF-resistant strain and resulted in complete elimination of RIF-resistant mycobacteria. Unfortunately, in mice with TB induced by a Beijing genotype strain, addition of SILA-421 to an isoniazid-rifampicin-pyrazinamide regimen for 13 weeks did not result in enhanced therapeutic efficacy

Scintigraphic imaging using 99mTc-labeled PEG liposomes allows early detection of experimental invasive pulmonary aspergillosis in neutropenic rats.

Item does not contain fulltextThe value of scintigraphic imaging using 99mTc labeled poly(ethyleneglycol) (PEG) -liposomes for detecting invasive pulmonary aspergillosis at different stages of the disease was investigated in a rat model. At 24, 48, 72, 120 and 168 h after fungal inoculation scintigraphic images were obtained and biodistribution of the radiolabel was determined. Findings were compared with serum galactomannan detection and other parameters of progression of fungal infection.At 48 h liposomal uptake in the infected left lung was increased significantly and 82% of the scintigraphic images was assessed positive. Serum galactomannan was only detected at 72 h and later. Liposomal uptake in the infected left lung increased over time and was significantly correlated with both the size of the pulmonary hemorrhagic lesion and the levels of circulating galactomannan. It was concluded that scintigraphic imaging using 99mTc-PEG-liposomes allows early detection of invasive pulmonary aspergillosis in this model, and that liposomal uptake in the infected lung was strongly associated with the severity of the disease

Scintigraphic imaging using 99mTc-labeled PEG liposomes allows early detection of experimental invasive pulmonary aspergillosis in neutropenic rats.

Item does not contain fulltextThe value of scintigraphic imaging using 99mTc labeled poly(ethyleneglycol) (PEG) -liposomes for detecting invasive pulmonary aspergillosis at different stages of the disease was investigated in a rat model. At 24, 48, 72, 120 and 168 h after fungal inoculation scintigraphic images were obtained and biodistribution of the radiolabel was determined. Findings were compared with serum galactomannan detection and other parameters of progression of fungal infection.At 48 h liposomal uptake in the infected left lung was increased significantly and 82% of the scintigraphic images was assessed positive. Serum galactomannan was only detected at 72 h and later. Liposomal uptake in the infected left lung increased over time and was significantly correlated with both the size of the pulmonary hemorrhagic lesion and the levels of circulating galactomannan. It was concluded that scintigraphic imaging using 99mTc-PEG-liposomes allows early detection of invasive pulmonary aspergillosis in this model, and that liposomal uptake in the infected lung was strongly associated with the severity of the disease

Consequences of Noncompliance for Therapy Efficacy and Emergence of Resistance in Murine Tuberculosis Caused by the Beijing Genotype of Mycobacterium tuberculosis.

Item does not contain fulltextDespite great effort by health organizations worldwide in fighting tuberculosis (TB), morbidity and mortality are not declining as expected. One of the reasons is related to the evolutionary development of Mycobacterium tuberculosis, in particular the Beijing genotype strains. In a previous study, we showed the association between the Beijing genotype and an increased mutation frequency for rifampin resistance. In this study, we use a Beijing genotype strain and an East-African/Indian genotype strain to investigate with our mouse TB model whether the higher mutation frequency observed in a Beijing genotype strain is associated with treatment failure particularly during noncompliance therapy. Both genotype strains showed high virulence in comparison to that of M. tuberculosis strain H37Rv, resulting in a highly progressive infection with a rapid lethal outcome in untreated mice. Compliance treatment was effective without relapse of TB irrespective of the infecting strain, showing similar decreases in the mycobacterial load in infected organs and similar histopathological changes. Noncompliance treatment, simulated by a reduced duration and dosing frequency, resulted in a relapse of infection. Relapse rates were correlated with the level of noncompliance and were identical for Beijing infection and East African/Indian infection. However, only in Beijing-infected mice, isoniazid-resistant mutants were selected at the highest level of noncompliance. This is in line with the substantial selection of isoniazid-resistant mutants in vitro in a wide isoniazid concentration window observed for the Beijing strain and not for the EAI strain. These results suggest that genotype diversity of M. tuberculosis may be involved in emergence of resistance and indicates that genotype-tailor-made treatment should be investigated.1 september 201

Scintigrafic imaging of bacterial and fungal infection in granulocytopenic rats.

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