Analysis of the Bacterial Diversity in Liver Abscess: Differences Between Pyogenic and Amebic Abscesses

Abstract

Abstract. Several recent studies have demonstrated that virulence in Entamoeba histolytica is triggered in the presence of both pathogenic and nonpathogenic bacteria species using in vitro and in vivo experimental animal models. In this study, we examined samples aspirated from abscess material obtained from patients who were clinically diagnosed with amebic liver abscess (ALA) or pyogenic liver abscess (PLA). To determine the diversity of bacterial species in the abscesses, we performed partial 16S rRNA gene sequencing. In addition, the E. histolytica and Entamoeba dispar species were genotyped using tRNA-linked short tandem repeats as specific molecular markers. The association between clinical data and bacterial and parasite genotypes were examined through a correspondence analysis. The results showed the presence of numerous bacterial groups. These taxonomic groups constitute common members of the gut microbiota, although all of the detected bacterial species have a close phylogenetic relationship with bacterial pathogens. Furthermore, some patients clinically diagnosed with PLA and ALA were coinfected with E. dispar or E. histolytica, which suggests that the virulence of these parasites increased in the presence of bacteria. However, no specific bacterial groups were associated with this effect. Together, our results suggest a nonspecific mechanism of virulence modulation by bacteria in Entamoeba.

Discrimination Experiments in Entamoeba and Evidence from Other Protists Suggest Pathogenic Amebas Cooperate with Kin to Colonize Hosts and Deter Rivals

“…(e.g., E. histolytica or E. dispar ) form abscesses in the host's tissues and/or organs (i.e., the Reyna‐Fabián et al. 's study, above), it is possible that amebas segregate spatially according to kinship and clone identity, similar to the segregation observed in social amebas in the field or laboratory ( D. discoideum , D. purpureum , and D. giganteum ; Fortunato et al. ; Sathe et al.…”

“…This is relevant as abscesses are communities of microbes and studies suggest that they can be composed of genotype mixes (e.g., Reyna‐Fabián et al. ), although the prevalence of clonality in protistan infections is often assumed (Tibayrenc ; Tibayrenc and Ayala ; Tibayrenc et al. ); thus, clone segregation in abscesses needs to be confirmed.…”

“…), the ameba ability to discriminate/recognize taxa, clone, or kin will also facilitate fine‐scale (millimeter, perhaps microscopic) niche partitioning when invading the host and colonizing its tissues/organs, or forming abscesses (the latter as multitaxa communities of bacteria and ameba species and their clones; Reyna‐Fabián et al. ). Reyna‐Fabián et al.…”

“…Reyna‐Fabián et al. () have reported bispecies ( E. histolytica HM1:IMSS and E. dispar SAW‐760) infection in a liver abscess from a single human host in Mexico (genotyped as per tRNA short‐tandem repeats, STRs, 6DA, or DA(1), respectively; see Ali et al. for genotyping approach).…”

Recent advances in Entamoeba biology: RNA interference, drug discovery, and gut microbiome

“…Independent studies by Rani et al . 100 and Reyna-Fabian et al 101 demonstrated a significant role of gut microbiota and its influence in patients with amoebic liver abscesses.…”