TABLE 2.

ARB identified to datea

ARBHostbLife-stylePathogenicityReference
α proteobacteriad
    Afipia felisAcanthamoebaFacultative intracellularUnknown157
    Afipia broomaeAcanthamoebaFacultative intracellularUnknown155
    Bosea spp.AcanthamoebaFacultative intracellularUnknown154
    Bradyrhizobium japonicumAcanthamoebaFacultative intracellularUnknown155
    Caedibacter acanthamoebaeAcanthamoebacFacultative intracellularUnknown114
    Ehrlichia-like organismSaccamoebacObligate intracellularUnknown182
    Mezorhizobium amorphaeAcanthamoebaExtracellularUnknown155
    Odyssella thelassonicensisAcanthamoebaFacultative intracellularUnknown27
    Paracaedibacter symbiosusAcanthamoebacFacultative intracellularUnknown114
    Paracaedibacter acanthamoebaeAcanthamoebacFacultative intracellularUnknown114
    “Rasbo bacterium”AcanthamoebaExtracellularUnknown150
    Rickettsia-likeAcanthamoebaObligate intracellularPotential80
β proteobacteriad
    Burkholderia cepaciaAcanthamoebaExtracellularEstablished148, 168
    Burkholdereria pseudomalleiAcanthamoebaExtracellularEstablished127
    Procabacter acanthamoebaAcanthamoebacFacultative intracellularUnknown115
    Ralstonia pickettiiAcanthamoebacExtracellularPotential180
γ proteobacteriad
    Coxiella burnetiiAcanthamoebaObligate intracellularEstablished158
    Escherichia coli O157AcanthamoebaExtracellularEstablished17
    Francisella tularensisAcanthamoebaFacultative intracellularEstablished25
    Legionella pneumophilaMany speciesFacultative intracellularEstablished209
    Legionella anisaAcanthamoebaFacultative intracellularPotential156
    Legionella lytica (formerly Sarcobium lyticum)AcanthamoebaFacultative intracellularPotential66, 67
    L. falloniiAcanthamoebaFacultative intracellularPotential5
    L. rowbothamiiAcanthamoebaFacultative intracellularPotential5
    L. drozanskiiAcanthamoebaFacultative intracellularPotential5
    L. drancourtiiAcanthamoebaFacultative intracellularPotential151
    Other LLAPAcanthamoebaFacultative intracellularPotential212
    Pseudomonas aeruginosaAcanthamoebacExtracellularEstablished178
    Vibrio choleraeAcanthamoeba, NaegleriaExtracellularEstablished237
ε proteobacteria
    Helicobacter pyloriAcanthamoebaFacultative intracellularEstablished248
Chlamydiaed
    Chlamydophila pneumoniaeAcanthamoebaObligate intracellularEstablished71
    Neochlamydia hartmanellaeHartmanellacObligate intracellularPotential118
    Parachlamydia acanthamoebaeAcanthamoebacObligate intracellularPotential7
    Simkania negevensisAcanthamoebaObligate intracellularEstablished133
Flavobacteria
    Amoebophilus asiaticusAcanthamoebacObligate intracellularUnknown116
    Flavobacterium spp.AcanthamoebaFacultative intracellularUnknown116, 187
Bacilli
    Listeria monocytogenesAcanthamoebaFacultative intracellularEstablished163
Actinobacteriad
    Molibuncus curtisiiAcanthamoebaExtracellularPotential241
    Mycobacterium lepraeAcanthamoebaObligate intracellularEstablished129
    Mycobacterium aviumAcanthamoebaFacultative intracellularEstablished45, 141, 224
    Mycobacterium marinumAcanthamoebaFacultative intracellularEstablished45, 141
    Mycobacterium ulceransAcanthamoebaFacultative intracellularEstablished141
    Mycobacterium simiaeAcanthamoebaFacultative intracellularPotential141
    Mycobacterium phleiAcanthamoebaFacultative intracellularPotential141
    Mycobacterium fortuitumAcanthamoebaFacultative intracellularPotential45, 141
    Mycobacterium smegmatisAcanthamoebaFacultative intracellularPotential141
  • a Among the ARB, some are natural hosts of free-living amoebae (identified within free-living amoebae isolated by amoebal enrichment), some were recovered by amoebal coculture (i.e., using as the cell background free-living amoebae), and some were found to be resistant to a given amoebal “host” in vitro. Some are obligate intracellular bacteria, while others are facultative intracellular bacteria or extracellular bacteria. Some are established human pathogens, while other are emerging potential pathogens, or, until now, strictly environmental species. The list does not include Enterobacteriaceae that have been shown to resist destruction by free-living amoebae only under non-physiological conditions, such as chlorination (137).

  • b Natural host, or grown by amoebal coculture.

  • c Natural host.

  • d Class, according to reference 86.