Development and evaluation of molecular tools for detecting and differentiating intestinal amoebae in healthy individuals.

Amoebae are single-celled parasites frequently colonizing human gut. However, few molecular tools are available for accurate identification. Here, we evaluated a panel of polymerase chain reactions (PCRs) targeting Entamoeba histolytica, Entamoeba dispar, Entamoeba coli, Entamoeba hartmanni, Entamoeba polecki, Endolimax nana and Iodamoeba bütschlii. Thirty-six faecal samples (18 containing at least one amoeba species by microscopy and 18 microscopy negative for amoebae) were tested. Real-time PCRs were used for detection and differentiation of E. histolytica and E. dispar. Conventional PCR with Sanger sequencing were applied for detection and differentiation of E. coli, E. hartmanni, E. polecki, E. nana and I. bütschlii. All microscopy results were confirmed by DNA-based methods. However, more samples were positive for single and mixed amoebic species by DNA-based assays than by microscopy (22 vs 18 and 7 vs 1, respectively). DNA sequencing allowed identification of E. coli subtypes (ST1 and ST2), showed low intra-specific variation within E. hartmanni, identified two phylogenetically distinct groups within E. nana, and identified Iodamoeba at the ribosomal lineage level. Taking into account the high intra-genetic diversity within some of the species at the small subunit (SSU) rRNA gene level, amplification of SSU rRNA genes with subsequent sequencing represents a useful method for detecting, differentiating and subtyping intestinal amoebae.

Rhizomastix biflagellata sp. nov., a new amoeboflagellate of uncertain phylogenetic position isolated from frogs.

The genus Rhizomastix contains five species of amoeboflagellates with a single anterior flagellum, which live as intestinal symbionts of insects and amphibians. Though established in 1911, Rhizomastix has been neglected for decades and its phylogenetic position is uncertain. This paper describes the morphology of the first cultivated strain of Rhizomastix. The organism was isolated from an argentine horned frog and differs from the known Rhizomastix species by the presence of biflagellate cells. The isolate is described as Rhizomastix biflagellata sp. nov. A possible relationship of Rhizomastix to Archamoebae is discussed.

Comparative study of entero-parasitic infections among HIV sero-positive and sero-negative patients in Lagos, Nigeria.

BACKGROUND: Intestinal parasites are endemic in many parts of the world where HIV infection is also widespread. Previous studies had shown that the spectrum of opportunistic and common endemic parasitic infections with HIV vary in different regions and usually reflect the infections prevalent in these regions. This present study was aimed at comparing the prevalence and types of intestinal parasitic infections in HIV sero-positive and sero-negative patients in Lagos. MATERIALS AND METHODS: Venous blood and stool samples of 1080 patients, recruited from three health care institutions were screened for HIV infection and intestinal parasites using HIV-1, HIV-2 rapid tests, direct wet mount with saline/iodine and formol-ether technique, respectively. RESULTS: Results showed that 6% (65/1080) of patients were sero-positive for HIV infection. In addition, 23.3% (252/1080) patients were infected with intestinal parasites and 33.8% (22/65) of patients with HIV had intestinal parasites co-infections. The prevalence of Entamoeba histolytica/Entamoeba dispar, Entamoeba coli, Iodamoeba butschilii, Giardia intestinalis, and Hookworm were statistically significantly higher among HIV sero-positive patients as compared to the HIV sero-negative patients. In addition, HIV sero-positive patients had higher odds of mixed intestinal parasites than the HIV sero-negative patients (9.1% versus 3.9%; adjusted OR 2.05, 95% CI, 1.14-3.72, P=0.021). CONCLUSION: In this study population, HIV sero-positive patients were more likely to have intestinal parasitic infections. The study underscores the public health significance of intestinal parasitic infections in HIV infected individuals.