A Rare Case of AICD Endocarditis caused by Staphylococcus Saprophyticus Treated Successfully with Antibiotics

摘要

To date, there have been two cases of endocarditis caused by S. saprophyticus reported in the literature; both involved native valves and had serious to deadly courses. We report the first case of endocarditis of a prosthesis due to S. saprophyticus; it appeared to affect the right atrium and possibly the mitral valve as well. The infection did not occur as a result of urinary tract infection; it is assumed that the causative agent may have entered the body through a tunneled catheter for hemodyalisis, though the catheter insertion site exhibited no signs of infection. In addition, this case represents the first report of endocarditis caused by S. saprophyticus that was successfully treated with antibiotic therapy. This case illustrates the potential for infection of a prosthesis in addition to native valves caused by S. saprophyticus and also the potential for successful treatment with antibiotics. Introduction Staphylococcus saprophyticus is a coagulase-negative staphylococcus (CoNS) species that is most commonly associated in humans with uncomplicated urinary tract infections in young, sexually active females (1). Rarely, infections due to S. saprophyticus have progressed to become more serious, causing acute pyelonephritis (2), septicemia (3) and nephrolithiasis (4). To date, S. saprophyticus has been reported as the cause of endocarditis twice in the literature (5, 6). In both cases, a native valve was affected. One case required valve replacement (5) and the other resulted in death of the patient (6). Here we present the first reported case of endocarditis of a prosthesis due to S. saprophyticus, as well as the first case of endocarditis caused by S. saprophyticus which was successfully treated with antibiotic therapy. Case Report A 58-year-old female presented to the emergency room with fatigue, fever, chills, shortness of breath upon exertion, intermittent chest pain and dry cough for the previous four days. She denied any nausea, vomiting, abdominal pain, urinary symptoms or diarrhea. She was receiving hemodialysis for end stage renal failure via a right internal jugular tunneled catheter. A blood culture taken by the primary care physician two days prior to admission was positive for CoNS. The patient's medical history was positive for hypertension, diabetes mellitus, coronary artery disease with PCI and hypercholesterolemia. She had stent placement in the left anterior descending artery after myocardial infarction five years prior to the current admission and implantable cardiac defibrillator (AICD) placement 3-4 weeks prior to the current admission. The catheter site showed no signs of infection. The patient reported drug allergies to penicillin, tetracycline, vancomycin and tobramycin; therefore, she was started on quinupristin/dalfopristin and ciprofloxacin to treat possible tunneled catheter infection. Removal of the catheter was considered, but it was decided to wait to determine whether there was improvement in symptoms after beginning treatment. TEE revealed a 5x3 mm, highly echogenic density on the tip of the anterior leaflet of the mitral valve with a small amount of independent motion, suggestive of a vegetation versus a calcification of the leaflet (Figure 1). The right atrium (RA) showed a pedunculated, medium-sized, echogenic density with a tiny, more mobile surface excrescence at the junction of the inferior vena cava and the RA cavity consistent with a vegetation. There was also a 12x10 mm, fixed density with a mobile excrescence at the junction of the RA and the superior vena cava involving the catheter representing a vegetation or thrombus (Figure 2). There was moderate regurgitation of the mitral and tricuspid valves. Four blood cultures (from arm) taken on the first three days of admission grew Staphylococcus saprophyticus/CoNS that was resistant to ampicillin, cefazolin, cefepime, cefotaxime, ciprofloxacin, amoxicillin, gentamicin, imipenem and oxacillin. Treatment was switched to quinupristin/da