A pathogen or a contaminant: the emerging significance of Kytococcus schroeteri

Abstract number: 1134_04_42

Becker K., Berchiche C., Aepinus C., Wüllenweber J., Etienne J., Podbielski A., Herrmann M., Peters G., von Eiff C.

Background:  

‘Micrococci’ are found as normal inhabitants of human skin and mucous membranes and are usually disregarded as contaminants in clinical isolates. Nevertheless, strains identified as members of the Micrococcinae suborder have been described to be increasingly involved as causative organisms in septicemia, endocarditis peritonitis, pneumonia and other severe systemic infections.

Patients and results:  

Following the recent description of Kytococcus schroeteri, four severe infections due to this pathogen were observed in different hospitals. After the first case, reporting a prosthetic valve endocarditis in a 34-year-old female without any other known diseases, a K. schroeteri infection associated with a prosthetic aortic valve was observed in a 38-year-old diabetic women. A further prosthetic valve infection affected the mitral valve of a 79-year-old patient. The first fatal case due to K. schroeteri was noted in a patient with asthma chronically treated with corticosteroids. This 71-year-old female referred to a French medical ICU for management of severe respiratory distress developed bacteremic pneumonia leading to distributive shock that progressed to multiorgan failure. In addition to phenotypical analyses, all isolates were confirmed on species level by 16S rDNA sequencing. K. schroeteri strains hitherto recovered were resistant to penicillin and oxacillin, but susceptible to glycopeptides, gentamicin, and rifampin. Of particular interest, rifampin in combination with other antibiotics (gentamicin, glycopeptides) was administered in all non-fatal cases.

Conclusions:  

Though it appears to be an organism of low virulence, the emerging number of reported cases of K. schroeteri infection has established the pathogenic potential of this organism. Thus, if an infection is clinically suspected, the repeated isolation of such isolates in the absence of other microorganisms should not be underestimated. Accurate identification of Kytococci is of importance as these species have been shown to be resistant to penicillin and -lactamase-resistant penicillins in contrast to members of other ‘micrococcal’ genera.