Clinical Spectrum of Infections Due to the Newly Described <i>Actinomyces</i> Species <i>A. turicensis</i> , <i>A. radingae</i> , and <i>A. europaeus</i>

<jats:title>ABSTRACT</jats:title> <jats:p> Over a 7-year period, we isolated 294 <jats:italic>Actinomyces</jats:italic> -like organisms (ALOs) which were not clearly identifiable. Using well-defined probes coding for sequences specific for recently described <jats:italic>Actinomyces</jats:italic> species ( <jats:italic>A. turicensis</jats:italic> , <jats:italic>A. radingae</jats:italic> , and <jats:italic>A. europaeus</jats:italic> ), we were able to identify 128 strains. The majority belonged to the <jats:italic>A. turicensis</jats:italic> species. <jats:italic>A. radingae</jats:italic> was found only in patients with skin-related pathologies. <jats:italic>A. europaeus</jats:italic> was also detected in patients with urinary tract infections. The main sources of <jats:italic>A. turicensis</jats:italic> were genital infections, followed by skin-related and urinary tract infections. Additional clinical pictures were appendicitis, cholecystitis, ear, nose, and throat infections, and bacteremia. In a small number of patients these ALOs were found as the only pathogen. Strains of the three species were tested by two widely used biochemical identification methods. <jats:italic>A. turicensis</jats:italic> was easily identifiable by both these methods. We conclude that these ALOs are not infrequent pathogens and are found in a wide range of human infections. At least <jats:italic>A. turicensis</jats:italic> is easily identifiable by clinical diagnostic laboratories. </jats:p>