environmental assay data sheet

Acanthamoeba PCR test

Test code: X0051 - Ultrasensitive qualitative detection of Acanthamoeba by real time PCR

Acanthamoeba are single-celled, free-living amoebae commonly found in environmental sources such as soil, freshwater, saltwater, air, dust, and even tap water or air conditioning systems. These organisms are widespread globally and typically feed on bacteria. They are opportunistic pathogens in humans and animals under certain conditions.

Acanthamoeba has two main stages during its life cycle. The trophozoite form is the active motile stage (typically 14-40 μm in size) that is responsible for feeding, growth, and reproduction via mitosis. This is the infective form that can invade host tissues. The cyst form is a dormant, double-walled stage that forms under stressful conditions, such as lack of food or exposure to disinfectants. Cysts are highly resistant to extreme environmental conditions, including chlorine and many antibiotics, so that the organism can survive for extended periods. Acanthamoeba does not have a flagellated stage and does not require a host for its life cycle, so it is truly free-living. Some species of Acanthamoeba can act as "Trojan horses" to carry intracellular bacteria, which can worsen a host’s infection.

Infection with Acanthamoeba in most cases is harmless and does not cause disease. However, infection with certain species, such as A. castellanii, A. culbertsoni, and A. polyphaga, can cause rare but serious complications, particularly in individuals with weakened immune systems or those with breached tissue barriers. The protozoan can enter through eyes, nasal passages, broken skin, or open wounds. Acanthamoeba keratitis, a painful eye infection affecting the cornea, is often linked to poor contact lens hygiene, such as using tap water or homemade solutions. It can lead to vision loss if untreated. Granulomatous amebic encephalitis is a severe, often fatal brain infection (mortality ~95%) that progresses slowly, causing brain swelling via protease secretion. It typically affects those with weakened immune systems, such as AIDS patients, and enters via the bloodstream after initial skin or lung entry.

Other Acanthamoeba infections include cutaneous lesions, sinusitis, or disseminated disease involving the lungs or sinuses, especially in immunocompromised hosts. Prevention of the infection relies on good personal hygiene, such as avoiding using tap water for contact lenses, cleaning lenses properly, and protecting wounds from environmental exposure.

Traditional methods of diagnosing Acanthamoeba infection include direct microscopy and culture. These methods have low sensitivity and specificity. Polymerase chain reaction (PCR) is increasingly being used to provide rapid, sensitive, and specific detection of this organism (Itahashi et al., 2011; Year et al., 2007).

Utilities:

• Check for Acanthamoeba in water sources, soil, and other environmental samples
• Selection of appropriate remediation regimens
• Check for post-remediation absence of this agent
• Help confirm the presence of this agent in animals
• Help minimize human exposure to this agent

References:

Itahashi M, Higaki S, Fukuda M, Mishima H, Shimomura Y. Utility of real-time polymerase chain reaction in diagnosing and treating Acanthamoeba keratitis. Cornea. 2011 Nov;30(11):1233-7.

Specimen requirements: 2 ml of water, or water filter media; or 10 ml of soil; or environmental swabs or swipes; or 0.2 ml CSF or fresh, frozen or fixed tissue.

Contact Zoologix if advice is needed to determine an appropriate specimen type for a specific diagnostic application. For specimen types not listed here, please contact Zoologix to confirm specimen acceptability and shipping instructions.

For all specimen types, if there will be a delay in shipping, or during very warm weather, refrigerate specimens until shipped and ship with a cold pack unless more stringent shipping requirements are specified. Frozen specimens should be shipped so as to remain frozen in transit. See shipping instructions for more information.

Turnaround time: 2 business days

Methodology: Qualitative real time polymerase chain reaction

Normal range: Nondetected