Isolation, identification and increasing importance of 'free-living' amoebae causing human disease

Zsuzsanna Szénási, T. Endo, K. Yagita, E. Nagy

Research output: Contribution to journalArticle

74 Citations (Scopus)

Abstract

Amphizoic small amoebic protozoa are capable of existing both in 'free-living' and in 'parasitic' form depending on the actual conditions. Two genera (Naegleria and Acanthamoeba) have become recognised as opportunist human parasites. Since the first description in 1965 of a lethal case of primary amoebic meningoencephalitis (PARI) caused by Naegleria, many more (mostly lethal) cases have been reported, while granulomatous amoebic encephalitis (GAE), as well as eye (keratinitis, conjunctivitis, etc.), ear, nose, skin and internal organ infections caused by Acanthamoeba have also occurred in rapidly increasing numbers. Both pathogenic and non-pathogenic species of Naegleria and Acanthamoeba are found worldwide in water, soil and dust, where they provide a potential source of infection. Successful differential diagnosis and appropriate (specific) therapy depends on precise laboratory identification of the 'free-living' amoebae. In most cases, isolation from the environment can be achieved, but identification and differentiation of the pathogenic and non-pathogenic strains is not easy. The methods presently available do not fulfil completely the requirements for specificity, sensitivity and reliability. Morphological criteria are inadequate, while thermophilic character, pH dependency and even virulence in infected mice, are not unambiguous features of pathogenicity of the different strains. More promising are molecular methods, such as restriction endonuclease digestion of whole-cell DNA or mitochondrial DNA, as well as iso-enzyme profile analysis after iso-electric focusing and staining for acid phosphatase and propionyl esterase activity. Use of appropriate monoclonal antibodies has also yielded promising results in the differentiation of human pathogenic and non-pathogenic strains. However, quicker, simpler, more specific and reliable methods are still highly desirable. The significance of endosymbiosis (especially with Legionella strains) is not well understood. The results of a systematic survey in Hungary for the isolation and identification of 'free-living' amoebae, including an investigation of the Hungarian amoebic fauna, the isolation of possibly pathogenic Naegleria in strains and of some Acanthamoeba strains from eye diseases, as well as the finding of a case of endosymbiosis, are also reported here.

Original languageEnglish
Pages (from-to)5-16
Number of pages12
JournalJournal of Medical Microbiology
Volume47
Issue number1
Publication statusPublished - 1998

Fingerprint

Naegleria
Acanthamoeba
Amoeba
Symbiosis
Virulence
Acetylesterase
Legionella
Conjunctivitis
Eye Diseases
Hungary
DNA Restriction Enzymes
Encephalitis
Acid Phosphatase
Infection
Dust
Mitochondrial DNA
Nose
Ear
Digestion
Parasites

ASJC Scopus subject areas

  • Microbiology (medical)
  • Microbiology

Cite this

Isolation, identification and increasing importance of 'free-living' amoebae causing human disease. / Szénási, Zsuzsanna; Endo, T.; Yagita, K.; Nagy, E.

In: Journal of Medical Microbiology, Vol. 47, No. 1, 1998, p. 5-16.

Research output: Contribution to journalArticle

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