Corynebacterium striatum is a commensal of human skin and has been recently recognized as an emerging pathogen. A case of nosocomial pacemaker lead endocarditis due to a multidrug-resistant C. striatum strain is described, highlighting the role of sonication as a diagnostic tool in cardiac device infections.
CASE REPORTA 71-year-old woman, who underwent pacemaker replacement 2 months before, was admitted with a 15-day history of fever and generator site pain. She was febrile (core temperature, 38.5°C), her blood pressure was 120/80 mmHg, and her pulse rate was 76 beats/min. Erythema, warmth, tenderness, and purulent drainage were observed at the pocket site. Respiratory, abdominal, and neurological parameters were normal, and an examination of the heart showed a 2/6 systolic murmur. Laboratory analyses revealed a mild leukocytosis (11 ϫ 10 9 leukocytes/liter, 85% polymorphonuclear cells) and an erythrocyte sedimentation rate correspondent to 50 mm/h. A markedly increased C-reactive protein level (8 IU/liter) was observed.Two separate sets of blood and swab cultures obtained from purulent secretion at the pocket site yielded coagulase-negative Staphylococcus which showed resistance to methicillin and rifampin and susceptibility to vancomycin, teicoplanin, linezolid, and daptomycin.A transthoracic echocardiogram revealed a mobile mass adherent to the intracardiac lead in the absence of valve vegetations. Treatment with daptomycin (6 mg/kg body weight once daily) was started, leading to a rapid improvement, as determined by clinical and laboratory findings. Blood cultures and pocket swabs, performed 72 h after the beginning of antimicrobial therapy, were sterile. Serum bactericidal activity was Ͼ1:16 (4). After 7 days of daptomycin treatment, the patient developed renal failure (clearance of creatinine, Ͻ20 ml/min), and the antimicrobial therapy was switched to intravenous linezolid (600 mg twice daily). Following this therapy, the patient again became febrile (core temperature, 39°C). Blood cultures and pocket site swabs were negative. The patient underwent device removal, and a reimplantation of a new pacemaker was performed 8 days later. On macroscopic examination, the intracardiac portion of the electrode showed the presence of a mass adherent to the lead. Four samples of lead tips were collected: two of them were analyzed by following the traditional microbiological procedures without sonication, whereas the other two samples were submitted to device sonication and then cultured. Briefly, within 1 h from the removal, two lead tips were inoculated in Trypticase soy broth (TSB) which was incubated for 24 h and analyzed for bacterial growth. The other two lead tips were vortexed for 30 s and then sonicated in NaCl solution for 5 min at a frequency Ͼ20 kHz and finally vortexed again for another 30 s. The Ultrasonik 300 bath (Ney, BarkMeyer Division, Yucaipa, CA) was used for sonication. The resulting sonication fluid was centrifuged at 3,200 rpm for 15 min, and the sediment was used for microbiological cultures. A...