Molecular Detection of Bacterial Endosymbionts in Acanthamoeba spp.: A Preliminary Study

Acanthamoeba spp. is a free-living amoeba commonly found in the environment. It  is  the  causative   agent  of  Acanthamoeba  keratitis  (AK)  and  granulomatous amoebic  encephalitis (GAE).  This  amoeba is  also  a  host  to  various  bacteria including  pathogenic ones such as Mycobacterium, Legionella, Pseudomonas and Methicillin-resistant Staphylococcus aureus (MRSA). In light of this information, a study was undertaken to detect  these bacterial  endosymbionts in Acanthamoeba spp.  isolated  from air-conditioning  outlets  in  wards  and  operating   theatres  in Universiti  Kebangsaan   Malaysia  Medical   Centre  (UKMMC).  The  presence  of these  bacteria  was screened using primer  pair targeting  each  genus  and  further confirmed by sequencing analysis. Twenty-nine  (80.56 %) Acanthamoeba isolates were  found  to contain  targeted  bacterial  endosymbiont with at least one  genus of bacteria  per isolates.  Mycobacterium spp. (82.76 %) were  the most common bacteria  detected, followed by Legionella spp. (65.52 %) and  Pseudomonas spp. (62.07  %).  No  MRSA were  detected in any  isolates  used  in this study.  Most of the  Mycobacterium endosymbionts were  non-tuberculous mycobacteria, while only two were part of Mycobacterium tuberculosis  complex group. We conclude that most Acanthamoeba have  the potential  to host various pathogenic bacteria. However, the implication on the pathogenicity of both organisms remains unclear and further investigations  are needed.