Dulanthi Weerasekera

Probiotic supplements are suggested to promote human health by preventing pathogen colonization. However, the mechanistic bases for their efficacy in vivo are largely uncharacterized. Here using metabolomics and bacterial genetics, we show that the human oral probiotic Streptococcus salivarius K12 (SAL) produces salivabactin, an antibiotic that eff...

Objectives: In frame of a study to characterize the interaction of human macrophage-like cells with pathogenic corynebacteria, Corynebacterium diphtheriae and Corynebacterium ulcerans, live cell imaging experiments were carried out and time lapse fluorescence microscopy videos were generated, which are presented here. Data description: The time...

When infecting a human host, Corynebacterium diphtheriae and Corynebacterium ulcerans are able to impair macrophage maturation and induce cell death. However, the underlying molecular mechanisms are not well understood. As a framework for this project, a combination of fluorescence microscopy, cytotoxicity assays, live cell imaging, and fluorescenc...

In order to further analyse the structure of DIP0733, its sequence was cloned in pBADMycHis ara and expressed in E. coli BL21. Different protocols for DIP0733 expression have been optimized and the purified protein was obtained in the membrane fraction. Following the pelleting of unbroken cells after lysis, the supernatant was spun again at 48400 g...

Diphtheria toxin is one of the best investigated bacterial toxins and the major virulence factor of toxigenic Corynebacterium diphtheriae and Corynebacterium ulcerans strains. However, also diphtheria toxin-free strains of these two species can cause severe infections in animals and humans, indicating the presence of additional virulence factors. I...

Seven non-toxigenic C. diphtheriae strains and one toxigenic strain were analyzed with regard to their interaction with murine macrophages (BMM) and human THP-1 macrophage-like cells. Proliferation assays with BMM and THP-1 revealed similar intracellular CFUs for C. diphtheriae strains independent of the host cell. Strain ISS4060 showed highest int...

Background: The transmission dynamics of Mycobacterium tuberculosis (Mtb) using various genotyping tools has been studied globally and a particular tool for genotyping Mtb is the mycobacterial interspersed repetitive units-variable number tandem repeats (MIRU-VNTR). Tuberculosis (TB) remains an important public health problem worldwide and Sri Lank...

Corynebacterium diphtheriae is the causative agent of respiratory diphtheria, a major cause of infant mortality until the 1930s (Hadfield et al., 2000; Burkovski, 2014). Although the incidence of diphtheria has declined due to vaccination with diphtheria toxoid, the disease has not been completely eradicated. Moreover, the occurrence of non-toxigen...

Background: Corynebacterium diphtheriae is the etiologic agent of diphtheria and different systemic infections. The bacterium has been classically described as an extracellular pathogen. However, a number of studies revealed its ability to invade epithelial cells, indicating a more complex pathogen-host interaction. The molecular mechanisms contro...

The incidence and prevalence of non-tuberculous mycobacteria [NTM] and associated respiratory diseases are on the rise but it is not a reportable disease in many countries. Over the past two decades molecular tools have contributed significantly in identifying many novel species of NTM, their virulence as well as differentiating their pathogenic is...

Corynebacterium diphtheriae is typically recognized as a colonizer of the upper respiratory tract (respiratory diphtheria) and the skin (cutaneous diphtheria). However, different strains of Corynebacterium diphtheriae can also cause invasive infections. In this study, the characterization of a non-toxigenic Corynebacterium diphtheriae strain (desig...

Rapid distinguishing of mycobacterial species and knowledge about their susceptibility is vital for the management of patients with pulmonary disease who are not responding to initial treatment as the mycobacteria have a spectrum of virulence and different susceptibilities to antibiotics. Most biochemical techniques used for species differentiation...

Multidrug-resistant tuberculosis (MDR-TB) is tuberculosis due to organisms which show high-level resistance to both isoniazid and rifampin and the accurate diagnosis of MDR-TB requires a positive culture of Mycobacterium tuberculosis (Mtb) and drug susceptibility testing. According to literature rifampin (RIF) resistance is considered as a marker f...

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Objective: To characterize the Mycobacterium tuberculosis (M. tuberculosis) isolates by spoligotyping and mycobacterial interspersed repetitive unit-variable number tandem repeat (MIRU-VNTR) typing to understand how M. tuberculosis strains transmit among the study population. Methods: Spoligotyping and MIRU-VNTR were used to genotype M. tuberculosi...

Background/Objectives: To characterize the Mycobacterium tuberculosis (MTB) isolates by spoligotyping and Mycobacterial Interspersed Repetitive Unit-Variable Number Tandem Repeat (MIRU-VNTR) typing to understand how MTB strains transmit among the study population. Methods: Spoligotyping and MIRU-VNTR were used to genotype the MTB isolates obtained...

MCAG consists of a cluster of rapidly growing Mycobacteria. Though uncommon, infections due to these organisms have been reported. The objective of this case study is to identify the causative organisms in sputum of a patient who was suffering from a pulmonary infection unresponsive to treatment using SYBR Green mediated Real time PCR1. In June 201...

Objectives: To identify mycobacterial species in bronchoscopy specimens with a simple assay based on polymerase chain reaction and restriction enzyme digestion. Methods: Sputum smear negative, bronchoscopy specimens (n=202) were collected from patients attending the Central Chest Clinic and the Teaching Hospital Kandy, Sri Lanka. DNA, extracted...