Balamuthia mandrillaris: An opportunistic, free-living ameba - An updated review

Functional annotation and comparative genomics analysis of Balamuthia mandrillaris reveals potential virulence-related genes

Balamuthia mandrillaris is a pathogenic protozoan that causes a rare but almost always fatal infection of the central nervous system and, in some cases, cutaneous lesions. Currently, the genomic data for this free-living amoeba include the description of several complete mitochondrial genomes. In contrast, two complete genomes with draft quality are available in GenBank, but none of these have a functional annotation. In the present study, the complete genome of B. mandrillaris isolated from a freshwater artificial lagoon was sequenced and assembled, obtaining an assembled genome with better assembly quality parameter values than the currently available genomes. Afterward, the genome mentioned earlier, along with strains V039 and 2046, were subjected to functional annotation. Finally, comparative genomics analysis was performed, and it was found that homologous genes in the core genome potentially involved in the virulence of Acanthamoeba spp. and Trypanosoma cruzi. Moreover, eleven of fifteen genes were identified in the three strains described as potential target genes to develop new treatment approaches for B. mandrillaris infections. These results describe proteins in this protozoan's complete genome and help prioritize which target genes could be used to develop new treatments.

Anti-Balamuthia mandrillaris and anti-Naegleria fowleri effects of drugs conjugated with various nanostructures

Balamuthia mandrillaris and Naegleria fowleri are protist pathogens that can cause fatal infections. Despite mortality rate of > 90%, there is no effective therapy. Treatment remains problematic involving repurposed drugs, e.g., azoles, amphotericin B and miltefosine but requires early diagnosis. In addition to drug discovery, modifying existing drugs using nanotechnology offers promise in the development of therapeutic interventions against these parasitic infections. Herein, various drugs conjugated with nanoparticles were developed and evaluated for their antiprotozoal activities. Characterizations of the drugs' formulations were accomplished utilizing Fourier-transform infrared spectroscopy, efficiency of drug entrapment, polydispersity index, zeta potential, size, and surface morphology. The nanoconjugates were tested against human cells to determine their toxicity in vitro. The majority of drug nanoconjugates exhibited amoebicidal effects against B. mandrillaris and N. fowleri. Amphotericin B-, Sulfamethoxazole-, Metronidazole-based nanoconjugates are of interest since they exhibited significant amoebicidal effects against both parasites (p < 0.05). Furthermore, Sulfamethoxazole and Naproxen significantly diminished host cell death caused by B. mandrillaris by up to 70% (p < 0.05), while Amphotericin B-, Sulfamethoxazole-, Metronidazole-based drug nanoconjugates showed the highest reduction in host cell death caused by N. fowleri by up to 80%. When tested alone, all of the drug nanoconjugates tested in this study showed limited toxic effects against human cells in vitro (less than 20%). Although these are promising findings, prospective work is warranted to comprehend the mechanistic details of nanoconjugates versus amoebae as well as their in vivo testing, to develop antimicrobials against the devastating infections caused by these parasites.

Encephalomyelomeningitis Caused by Balamuthia mandrillaris: A Case Report and Literature Review

Central nervous system infection by Balamuthia mandrillaris is a rare and severe condition, which has a fatality rate of approximately 95% and often evades timely diagnosis due to its rarity and non-specific clinical manifestations. Here, we report a case of encephalomyelomeningitis caused by B. mandrillaris in a male who presented with transient coma, nausea, and vomiting when working in a garbage dump. Initial magnetic resonance imaging (MRI) of the brain showed normal signals. Despite receiving steroids as well as antibacterial and antiviral treatment, he developed urinary and fecal dysfunction, inability to walk, and deterioration of consciousness. Both brain and spinal cord MRI revealed abnormal findings, and next-generation sequencing of the cerebrospinal fluid showed the presence of B. mandrillaris. A combination of fluconazole and albendazole was administered; however, the patient deteriorated gradually and died 30 days after the onset. We suggest the unbiased metagenomic sequencing of the affected tissues/CSF in patients with CNS infections that are difficult to diagnose or treat, and multiple tests at different stages of the disease may be required.