Medicine

Now showing 1 - 3 of 3

Distinct microbiome profiles and biofilms in Leishmania donovani-driven cutaneous leishmaniasis wounds
(Nature Publishing Group, 2021) Kaluarachchi, T.D.J.; Campbell, P.M.; Wickremasinghe, R.; Ranasinghe, S.; Wickremasinghe, R.; Yasawardene, S.; de Silva, H.; Menike, C.; Jayarathne, M.C.K.; Jayathilake, S.; Dilhari, A.; McBain, A.J .; Weerasekera, M.M.
The endemic strain of Leishmania donovani in Sri Lanka causes cutaneous leishmaniasis (CL) rather than more common visceral form. We have visualized biofilms and profiled the microbiome of lesions and unaffected skin in thirty-nine CL patients. Twenty-four lesions (61.5%) were biofilm-positive according to fluorescence in situ hybridization. Biopsies of biofilm-positive lesions were dominated by Pseudomonas, class Bacilli and Enterobacteriaceae and distinguished by significantly lower community evenness. Higher relative abundance of a class Bacilli OTU was detected in wound swabs versus contralateral skin. Wound swabs and biopsies had significantly distinct microbiome profiles and lower diversity compared to unaffected skin. Greater abundances of potentially pathogenic organisms were observed in wet ulcers, lesions with high parasite loads and large wounds. In summary, more than half of L. donovani associated CL wounds harboured biofilms and the wounds exhibited a distinct, less diverse, microbiome than unaffected skin.
Recent developments and future directions in the paratransgenesis based control of Leishmania transmission
(Elsevier, 2020) Wijerathna, T.; Gunathunga, S.; Gunathilaka, N.
ABSTRACT: Vector-borne diseases are one of the main concerns regarding global health. Among these, leishmaniasis stands as one of the most serious issues. This disease is transmitted via the bite of female phlebotomine sand flies. Due to the drawbacks such as the development of resistance associated with conventional vector control methods, paratransgenesis has become more popular in the recent past. A range of bacteria inhabit the gut of different species of sand flies. Bacillus subtilis, B. megaterium, and Enterobacter cloacae dissolvens are some of the common bacteria with ideal characteristics for this technique. Among the large number of natural anti-microbial peptides (AMPs) recovered from animals, DS hypo-01, Phylloseptin-1 and melittin are found to be the most effective. Hybrids of Cecropin A and melittin such as CA(1–8)M(1–18), D-CA(1–8)M(1–18) and N-Ac-CA(1–8)M(1–18) are also suitable candidates. Use of peptides initially released in an inactive form to activate upon exposure to a specific molecule is a potential solution for the lower specificity of AMPs. Single chain antibodies on the other hand, have high specificity, but effectiveness is lower than AMPs. The genetic transformation of the selected bacteria and the generation of paratransgenic sand flies through transtadial transmission are feasible under laboratory conditions. Safe delivery techniques such as microencapsulation are being tested to increase the specificity reducing environmental issues. Nevertheless, extensive studies with more practical approaches are required before applying this technique in the field. KEYWORDS: Leishmaniasis; Paratransgenesis; Antileishmanial peptides; Gut microbiota; Biological control.
Evaluation of rapid extraction and isothermal amplification techniques for the detection of Leishmania donovani DNA from skin lesions of suspected cases at the point of need in Sri Lanka
(BioMed Central, 2018) Gunaratna, G.; Manamperi, A.; Bohiken-Fascher, S.; Wickremasinghe, R.; Gunawardena, K.; Yapa, B.; Pathiana, N.; Pathirana, H.; de Silva, N.; Sooriyaarachchi, M.; Deerasinghe, T.; Mondal, D.; Ranasinghe, S.; Abd EI Wahed, A.
BACKGROUND: Leishmaniasis is a disease caused by vector-borne protozoans. In Sri Lanka, the cutaneous form of the disease is predominant, which is usually diagnosed using Giemsa-stained slit skin smear examination and by histology. However, the sensitivity of slit skin smears and histology are reportedly low. Moreover, facilities for the highly sensitive polymerase chain reaction (PCR) are available only in a few highly-equipped parasitology laboratories. Therefore, there is a need for low cost, sensitive and specific screening tests for diagnosis of leishmaniasis at the point of need. RESULTS: In this study, a mobile suitcase laboratory applying novel extraction (SpeedXtract) and isothermal amplification and detection (recombinase polymerase amplification assay, RPA) methods were evaluated for the diagnosis of cutaneous leishmaniasis in Sri Lanka. First, the developed assay was applied to three different sample types (punch biopsy, slit skin smears and fine needle aspirates) at a local hospital. The results showed that the 2 mm punch biopsy sample produced the best exponential amplification curve and early fluorescence signal in the RPA assay. Secondly, punch biopsies were collected from 150 suspected cutaneous leishmaniasis cases and screened with SpeedXtract/RPA, RNAlater/PCR and ATL buffer/PCR, in addition to Giemsa-stained slit skin smears. Fifty-seven samples were negative in all detection methods. In total 93 samples were positive with assay sensitivities of 65.5% (SpeedXtract/RPA), 63.4% (RNAlater/PCR) and 92.4% (ATL buffer/PCR). The Giemsa-stained slit skin smear delivered the worst clinical sensitivity (32.2%). CONCLUSIONS: The SpeedXtract/RPA method under field conditions took 35 min, while almost 8 h were needed to finalize the extraction and detection by PCR in the laboratory. The SpeedXtract/RPA method produced similar sensitivity to samples preserved in RNAlater and subjected to PCR amplification, but both were less sensitive than ATL-preserved samples subjected to PCR amplification. There is a need for a standardization of sample collection and nucleic acid extraction methods.

Medicine

Browse

Filters

Settings

Sort By

Results per page

Search Results