Potentially pathogenic Acanthamoeba genotype T4 isolated from dental units and emergency combination showers

BACKGROUND Acanthamoeba is the genus of free-living amoebae that is most frequently isolated in nature. To date, 20 Acanthamoeba genotypes have been described. Genotype T4 is responsible for approximately 90% of encephalitis and keratitis cases. Due to the ubiquitous presence of amoebae, isolation from environmental sources is not uncommon; to determine the clinical importance of an isolation, it is necessary to have evidence of the pathogenic potential of amoebae. OBJECTIVE The aim of this study was to physiologically characterise 8 Acanthamoeba T4 isolates obtained from dental units and emergency combination showers and to determine their pathogenic potential by employing different laboratory techniques. METHODS Eight axenic cultures of Acanthamoeba genotype T4 were used in pathogenic potential assays. Osmotolerance, thermotolerance, determination and characterisation of extracellular proteases and evaluation of cytopathic effects in MDCK cells were performed. FINDINGS All of the isolates were osmotolerant, thermotolerant and had serine proteases from 44-122 kDa. Two isolates had cytopathic effects on the MDCK cell monolayer. MAIN CONCLUSION The presence of Acanthamoeba T4 with pathogenic potential in areas such as those tested in this study reaffirms the need for adequate cleaning and maintenance protocols to reduce the possibility of infection with free-living amoebae.

Isolation of acanthamoeba genotype t4 from a non-contact lens wearer from the Philippines.

We report the case of a 76-year old Filipino male who presented with pain, redness, and blurring of vision of the right eye. Corneal scraping was done and sent to the St. Luke's Research and Biotechnology Group for detection and identification of the infectious agent. Morphological detection was performed by allowing the organism from the scraping to grow in 1.5% non-nutrient agar plate with heat-killed E. coli. Trophozoites with acanthopodia and double-walled cysts characteristic of Acanthamoeba were observed within the first and second week of observations, respectively. Molecular identification of the amoebae at the genus level based on the presence of Acanthamoeba-specific amplimer S1, ASA.S1 confirmed the morphological identification. Genotyping through sequence revealed that the organism belonged to T4, which is the genotype commonly present in the eye of keratitis patients.

Isolation of <i>Acanthamoeba</i> genotype T4 from a non-contact lens wearer from the Philippines

We report a case of a 76-year old Filipino male from the province of Porac, Pampanga who presented with pain, redness, and blurring of vision of the right eye (oculus dexter, OD) on 25 February 2009. One and a half weeks prior to consultation, patient complained of right eye discharge and lid swelling. The patient consulted an ophthalmologist and was given unrecalled topical eye medications. There was no improvement from the symptoms and patient complained of worsening pain and redness in the right eye. The patient was a non-contact lens wearer and he denied any trauma to the right eye. However, he admitted to washing both eyes with tap water. Visual acuity in the right eye was counting fingers at 3 feet. Slit lamp examination showed diffuse conjunctival injection. There was note of a ring-like infiltrate in the cornea almost extending to the limbus. There was also note of significant anterior chamber cells reaction and hypopyon. Primary working impression was Acanthamoeba keratitis (AK), OD. Corneal scraping was done and sent to the St. Luke's Research and Biotechnology for detection and identification of the infectious agent. Morphological detection was done by allowing the organism from the scraping to grow in 1.5% non-nutrient agar plate with heat-killed E. coli. Trophozoites with acanthopodia and double-walled cysts characteristic of Acanthamoeba were observed within the first and second week of observations, respectively. Molecular identification of the amoebae at the genus level based on the presence of Acanthamoeba-specific amplimer S1, ASA. S1 (a partial 18S ribosomal DNA gene) confirmed the morphological identification (band at 461-bp). Genotyping through sequence revealed that the organism belonged to T4, which is the genotype commonly present from the eye of keratitis patients.

Isolation of <i>Acanthamoeba</i> Genotype T4 from a Non-Contact Lens Wearer from the Philippines

We report the case of a 76-year old Filipino male who presented with pain, redness, and blurring of vision of the right eye. Corneal scraping was done and sent to the St. Luke’s Research and Biotechnology Group for detection and identification of the infectious agent. Morphological detection was performed by allowing the organism from the scraping to grow in 1.5% non-nutrient agar plate with heat-killed <i>E. coli</i>. Trophozoites with acanthopodia and double-walled cysts characteristic of <i>Acanthamoeba</i> were observed within the first and second week of observations, respectively. Molecular identification of the amoebae at the genus level based on the presence of <i>Acanthamoeba</i>-specific amplimer S1, ASA.S1 confirmed the morphological identification. Genotyping through sequence revealed that the organism belonged to T4, which is the genotype commonly present in the eye of keratitis patients.