Author: M. Auron, M.D, Department of Hospital Medicine, Cleveland Clinic
Reviewer: V. Dimov, M.D., Department of Hospital Medicine, Cleveland Clinic
A 50 yo male with type 2 diabetes mellitus (recent HbA1c 7.5%) was admitted with complaints of dysuria and non-specific abdominal pain for 1 week, accompanied by malaise followed by fevers and chills.
Glyburide 10 mg BID, Metformin 850 mg BID, Lisinopril 10 mg daily, ASA 81 mg daily.
The patient appeared ill, with low grade fever, marked tachycardia and orthostatic hypotension, but examination was otherwise nonspecific. No cardiac murmur was present, and the prostate was non-tender.
What is the most likely diagnosis?
Diabetic ketoacidosis and complicated urinary tract infection.
What tests would you order?
- Complete blood count with differential
- Basic metabolic panel
- Urinalysis and urine culture
- Blood culture
- Arterial Blood Gases.
Glucose of 441, WBC of 19,440 (73% segmented neutrophils, 17% band forms), sodium 126, CO2 18, creatinine of 1.7, and an arterial pH of 7.44.
Urinalysis demonstrated no leukocyte esterase or nitrite.
Blood cultures drawn on admission grew gram positive cocci in clusters, which proved to be methicillin-sensitive Staphylococcus aureus (MSSA), although urine cultures showed no growth.
What treatment would you start for this patient?
The patient should receive intensive intravenous fluid hydration with 0.9% NaCl in boluses until resolution of orthostatic changes; as well, prompt start of empirical intravenous broad spectrum antibiotics (vancomycin and piperacillin-tazobactam) should be done until cultures yield an organism. After blood cultures yielded MSSA antibiotics were change to gentamicin and cefazolin.
What happened next?
An abdominal computed tomography (CT) scan (Fig. 1) demonstrated a prostatic abscess extending to the seminal vesicles with largest diameter of 3 cm in the right seminal vesicle. A trans-rectal ultrasound-guided drainage of the abscess was performed with heavy growth of MSSA. A pigtail drainage catheter was inserted into the abscess cavity for 6 days, draining a total of 54 cc of purulent fluid. Resolution of the abscess was documented on a repeat CT scan.
Figure 1. Computed tomography scan of the pelvis: The seminal vesicles are enlarged and demonstrate fluid attenuation internally. The right seminal vesicle measures approximately 3 cm in size. This fluid attenuation extends into the prostate, which is also heterogeneous and mildly enlarged. There are surrounding inflammatory changes of the perivesical fat. The urinary bladder shows minimal thickening of the wall. Delayed images show no obvious intraluminal abnormalities with further opacification of the urinary bladder.
Initial transthoracic echocardiogram was done which was normal. However, in light of high-grade MSSA bacteremia a transesophageal echocardiogram (TEE) (Fig. 2) revealed 2 masses (4x4mm and 6x1mm) on the anterior leaflet of the mitral valve, consistent with vegetations.
Figure 2. Trans-esophageal echocardiogram: It can be appreciated the presence of a vegetation in the anterior leaflet of mitral valve; doppler shows surprisingly no significant mitral valve regurgitation.
Sterilization of blood cultures was achieved on iv cefazolin and gentamycin and patient had clinical improvement within several days. He was discharged to complete a 6-week course of cefazolin.
Staphylococcus aureus Prostatic abscess complicated by Infective Endocarditis.
What did we learn from this case?
Prostatic abscesses are unusual but severe infections involving significant morbidity, with a mortality rate reported to be as high as 30%. Prostate abscess is frequently associated with immunocompromised states and our patient was likely predisposed to both Staphylococcus aureus infection and prostatic abscess by his diabetes mellitus.
Diagnosis of prostate abscesses may be delayed because symptoms and clinical finding are often non-specific, and urine culture is frequently negative. In our patient, an initially normal rectal examination made diagnosis more difficult.
CT scan appears to be the optimal modality for both diagnosis and follow-up. Prostatic abscess due to Staphylococcus aureus is rare.
Given that our patient´s dysuria and lower abdominal pain began coincident with or just before onset of his constitutional symptoms, we postulate that the prostate was likely the initial site of infection, with subsequent bacteremic seeding of a presumably normal mitral valve. Cases of endocarditis caused by S. aureus in the absence of drug use are most commonly leftsided tend to occur in older patients, and have been reported to have a mortality rate as high as 44%.
S. aureus endocarditis typically has a rapid onset and frequently involves normal cardiac valves. Patients most often do not display classic stigmata of bacterial endocarditis upon initial presentation.
Definitive therapy of prostatic abscesses consists of drainage accompanied by adjunctive antibiotics, as most cases will not be cured by antibiotics alone. Trans-rectal ultrasound (TRUS) guided needle aspiration offers a less invasive, effective and simple therapeutic procedure with less morbidity than surgical drainage, and should be considered as an initial approach.
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