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Annals of Parasitology 2024Representatives of the genus Acanthamoeba are among the most widespread protists in the environment. They have a ubiquitous distribution and can sometimes cause quite...
Representatives of the genus Acanthamoeba are among the most widespread protists in the environment. They have a ubiquitous distribution and can sometimes cause quite serious pathologies in humans. The treatment ofp rotozoal infections caused by free-living amoebae is currently limited and often unsuccessful. In the presented investigation, amebicidal activity was determined against both the trophozoites and cysts of Acanthamoeba spp., which were isolated during the microbiological examination of environmental objects. The inhibitory activity of drugs in vitro was determined using the authors' proposed method, which is based on the plaque formation phenomenon: this is initiated by free-living amoebae when cultured in agar containing the bacteria Cellulosimicrobium sp. strain bent-1. Based on a series of experimental studies, the paper proposes a reliable and inexpensive method for determining the anti-protozoal activity of medicinal agents, which will significantly complement the current screening method system when studying existing drugs, or new drugs during their development stage.
Topics: Acanthamoeba; Antiprotozoal Agents; Trophozoites; Amebicides
PubMed: 38935775
DOI: 10.17420/ap7001.522 -
Pharmaceuticals (Basel, Switzerland) Jun 2024spp. can cause a sight threatening disease. At present, the current treatments used to treat spp. Infections, such as biguanide-based antimicrobials, remain...
spp. can cause a sight threatening disease. At present, the current treatments used to treat spp. Infections, such as biguanide-based antimicrobials, remain inefficacious, with the appearance of resistant forms and high cytotoxicity to host cells. In this study, an initial screening was conducted against Neff and murine macrophages J774A.1 using alamarBlue™. Among the 160 compounds included in the cited box, 90% exhibited an inhibition of the parasite above 80%, while only 18.75% of the compounds inhibited the parasite with a lethality towards murine macrophage lower than 20%. Based on the amoebicidal activity, the cytotoxicity assay, and availability, Terconazole was chosen for the elucidation of the action mode in two clinical strains, and L10. A fluorescence image-based system and proteomic techniques were used to investigate the effect of the present azole on the cytoskeleton network and various programmed cell death features, including chromatin condensation and mitochondria dysfunction. Taking all the results together, we can suggest that Terconazole can induce programmed cell death (PCD) via the inhibition of sterol biosynthesis inhibition.
PubMed: 38931475
DOI: 10.3390/ph17060808 -
Microorganisms Jun 2024Ophthalmologists' diagnostic and treatment competence in Acanthamoeba keratitis varies widely. This investigator-initiated, retrospective, single-center chart review...
Ophthalmologists' diagnostic and treatment competence in Acanthamoeba keratitis varies widely. This investigator-initiated, retrospective, single-center chart review examined the electronic patient files regarding PCR-positive Acanthamoeba keratitis. We included corneal and contact lens assessments. We further reviewed the patient's medical history, corneal scraping results regarding viral or fungal co-infections, and the duration from symptom onset to final diagnosis. We identified 59 eyes of 52 patients from February 2010 to February 2023, with 31 of 52 (59.6%) being female patients. The median (IQR, range) patient age was 33 (25.3 to 45.5 [13 to 90]) years, and the mean (SD, range) time to diagnosis after symptom onset was 18 (10.5 to 35 [3 to 70]) days. Overall, 7 of 52 (7.7%) patients displayed a bilateral Acanthamoeba infection, and 48 (92.3%) used contact lenses at symptom onset. Regarding other microbiological co-infections, we found virologic PCR testing in 45 of 52 (86.5%) patients, with 3 (6.7%) positive corneal scrapings. Fungal cultures were performed in 49 of 52 (94.2%) patients, with 5 (10.2%) positive corneal scrapings. The medical treatment success rate was 45/46 (97.8%). This study raises awareness of patient education in contact lens handling and screens for further microbial co-infections in suspected Acanthamoeba cases.
PubMed: 38930596
DOI: 10.3390/microorganisms12061214 -
Microorganisms Jun 2024, a widely distributed free-living amoeba found in various environments, is an opportunistic pathogen responsible for causing keratitis, a condition that may lead to...
, a widely distributed free-living amoeba found in various environments, is an opportunistic pathogen responsible for causing keratitis, a condition that may lead to blindness. However, identifying the pathogenicity of is challenging due to its complex life cycle, ability to adapt to different environments, variable virulence factors, and intricate interactions with the host immune system. Additionally, the development of an effective model for studying pathogenicity is limited, hindering a comprehensive understanding of the mechanisms underlying its virulence and host interactions. The aim of this study was to develop an ex vivo model for infection using porcine eyeballs and to evaluate the pathogenicity of the isolates. Based on slit lamp and biopsy analysis, the developed ex vivo model is capable of successfully infecting within 3 days. Histopathological staining revealed that clinical isolates of exhibited greater corneal stroma destruction and invasion in this model than environmental isolates. Our results highlight the importance of an ex vivo porcine eye model in elucidating the pathogenesis of infection and its potential implications for understanding and managing -related ocular diseases.
PubMed: 38930543
DOI: 10.3390/microorganisms12061161 -
Pathogens (Basel, Switzerland) May 2024keratitis (AK) is a severe infection of the cornea. Prevention and treatment are difficult due to the inefficacy of currently available compounds. The impact of many...
keratitis (AK) is a severe infection of the cornea. Prevention and treatment are difficult due to the inefficacy of currently available compounds. The impact of many commonly used compounds for routine examinations of is unexplored but might offer insight useful in combatting AK. In this study, we demonstrate that sodium metabisulfite, a common preservation constituent of eye care solutions, was found to be active against trophozoites at concentrations lower than that commonly found in eye drops (IC 0.03 mg/mL). We demonstrate that sodium metabisulfite depletes thiamine from growth medium and that is a thiamine auxotroph, requiring thiamine salvage for growth. The inhibitory effects of sodium metabisulfite can be overcome by thiamine supplementation. These results are consistent with the lack of key enzymes for thiamine biosynthesis in the genome of , an area which might prove exploitable using new or existing compounds. Indeed, this study highlights sodium metabisulfite as a useful inhibitor of trophozoites in vitro and that it acts, at least in part, by limiting available thiamine.
PubMed: 38921729
DOI: 10.3390/pathogens13060431 -
PloS One 2024Exploration of interspecies interactions between microorganisms can have taxonomic, ecological, evolutionary, or medical applications. To better explore interactions...
Exploration of interspecies interactions between microorganisms can have taxonomic, ecological, evolutionary, or medical applications. To better explore interactions between microorganisms it is important to establish the ideal conditions that ensure survival of all species involved. In this study, we sought to identify the ideal biotic and abiotic factors that would result in high co-culture viability of two interkingdom species, Pseudomonas aeruginosa and Acanthamoeba castellanii, two soil dwelling microbes. There have been limited studies showing long-term interactions between these two organisms as co-culture can result in high mortality for one or both organisms suggesting a predator-predator interaction may exist between them. In this study, we identified biotic and abiotic conditions that resulted in a high viability for both organisms in long-term co-culture, including optimizing temperature, nutrient concentration, choice of bacterial strains, and the initial ratio of interacting partners. These two species represent ideal partners for studying microbial interactions because amoebae act similarly to mammalian immune cells in many respects, and this can allow researchers to study host-pathogen interactions in vitro. Therefore, long-term interaction studies between these microbes might reveal the evolutionary steps that occur in bacteria when subjected to intense predation, like what occurs when pathogens enter the human body. The culture conditions characterized here resulted in high viability for both organisms for at least 14-days in co-culture suggesting that long-term experimental studies between these species can be achieved using these culture conditions.
Topics: Acanthamoeba castellanii; Pseudomonas aeruginosa; Coculture Techniques; Microbial Interactions; Temperature; Soil Microbiology
PubMed: 38913685
DOI: 10.1371/journal.pone.0305973 -
Acta Tropica Jun 2024Soluble factors in the secretome of Acanthamoeba castellanii play crucial roles in the pathogenesis of Acanthamoeba keratitis (AK). Investigating the pathological...
Soluble factors in the secretome of Acanthamoeba castellanii play crucial roles in the pathogenesis of Acanthamoeba keratitis (AK). Investigating the pathological effects of A. castellanii-derived conditioned medium (ACCM) on ocular cells can provide insights into the damage inflicted during AK. This study examined ACCM-induced cytotoxicity in primary human corneal stromal cells (CSCs) and a human SV40 immortalized corneal epithelial cell line (ihCECs) at varying ACCM concentrations (25 %, 50 %, 75 %, and 100 %). MTT, AlamarBlue, Sulforhodamine B, lactate dehydrogenase, and Caspase-3/7 activation assays were used to assess the impact of ACCM on the cell viability, proliferation and apoptosis. Additionally, fluorescent staining was used to reveal actin cytoskeleton changes. ACCM exposure significantly decreased cell viability, increased apoptosis, and disrupted the actin cytoskeleton, particularly at higher concentrations and longer exposures. Proteases were found to mediate these cytopathogenic effects, highlighting the need for characterization of A. castellanii proteases as key virulence factors in AK pathogenesis.
PubMed: 38901524
DOI: 10.1016/j.actatropica.2024.107288 -
Survey of Ophthalmology Jun 2024Acanthamoeba keratitis (AK) is a rare, sight-threating corneal infection. The disease is challenging to diagnose and treat, and the amoeba can rapidly encyst, persisting...
Acanthamoeba keratitis (AK) is a rare, sight-threating corneal infection. The disease is challenging to diagnose and treat, and the amoeba can rapidly encyst, persisting in the tissue and causing recurrences. Medical therapy is conventionally considered the first line treatment, but advanced cases could require more invasive treatments like a "chaud" corneal transplant. We review the incidence of severe complications in patients affected byAK. Of 439 reports screened, 158 met our inclusion criteria. Incidence of severe complications was low, with 2.21% patients developing perforation, 1% requiring evisceration/enucleation and less than 1% developing endophthalmitis. Corneal transplantation was required in 16.68% of the cases. According to our results, and considering the reported incidences of these complications in other infectious keratitis, AK patients have an overall low risk of developing perforation, endophthalmitis, and enucleation/evisceration. Nevertheless, data available in literature remain poor, and further randomized control trials are needed to confirm our findings.
PubMed: 38885760
DOI: 10.1016/j.survophthal.2024.06.001 -
Scientific Reports Jun 2024Natural products play a significant role in providing the current demand as antiparasitic agents, which offer an attractive approach for the discovery of novel drugs....
Natural products play a significant role in providing the current demand as antiparasitic agents, which offer an attractive approach for the discovery of novel drugs. The present study aimed to evaluate in vitro the potential impact of seaweed Padina pavonica (P. pavonica) extract in combating Acanthamoeba castellanii (A. castellanii). The phytochemical constituents of the extract were characterized by Gas chromatography-mass spectrometry. Six concentrations of the algal extract were used to evaluate its antiprotozoal activity at various incubation periods. Our results showed that the extract has significant inhibition against trophozoites and cysts viability, with complete inhibition at the high concentrations. The IC of P. pavonica extract was 4.56 and 4.89 µg/mL for trophozoites and cysts, respectively, at 24 h. Morphological alterations of A. castellanii trophozoites/cysts treated with the extract were assessed using inverted and scanning electron microscopes and showed severe damage features upon treatment with the extract at different concentrations. Molecular Docking of extracted compounds against Acanthamoeba cytochrome P450 monooxygenase (AcCYP51) was performed using Autodock vina1.5.6. A pharmacokinetic study using SwissADME was also conducted to investigate the potentiality of the identified bioactive compounds from Padina extract to be orally active drug candidates. In conclusion, this study highlights the in vitro amoebicidal activity of P. pavonica extract against A. castellanii adults and cysts and suggests potential AcCYP51 inhibition.
Topics: Acanthamoeba castellanii; Molecular Docking Simulation; Acanthamoeba Keratitis; Plant Extracts; Antiprotozoal Agents; Trophozoites; Animals; Humans
PubMed: 38871751
DOI: 10.1038/s41598-024-63691-8 -
BMJ Case Reports Jun 2024Granulomatous amoebic encephalitis due to spp is a rare, near-fatal central nervous system infection. It is often seen in immunocompromised individuals. Here we...
Granulomatous amoebic encephalitis due to spp is a rare, near-fatal central nervous system infection. It is often seen in immunocompromised individuals. Here we describe a survivor of this infection who was co-infected with multidrug-resistant tuberculosis. He presented to us with features of meningitis and a history of chronic cough. The chest X-ray was classical for pulmonary tuberculosis. Neuroimaging was suggestive of encephalitis; herpes simplex virus PCR was negative. Cerebrospinal fluid (CSF) showed lymphocytic pleocytosis. Wet mounts revealed trophozoites of Currently, he is being treated with oral bedaquiline, levofloxacin, linezolid, clofazimine, cycloserine and pyridoxine for tuberculosis. He received intravenous amikacin and oral cotrimoxazole and fluconazole for infection for 1 month. The resolution was confirmed by repeating the CSF wet mount, culture and neuroimaging. He was then discharged with oral rifampicin, cotrimoxazole and fluconazole. He is currently under our close follow-up.
Topics: Humans; Male; Acanthamoeba; Tuberculosis, Meningeal; Amebiasis; Tuberculosis, Multidrug-Resistant; Immunocompetence; Coinfection
PubMed: 38871639
DOI: 10.1136/bcr-2024-260613