Dual perinephric and prostatic abscesses from methacillin-resistant Staphylococcus aureus.

Abstract: Perinephric and prostatic abscesses may present with protean symptoms and often arise from ascending urinary tract infections. Both abscesses are often caused by uropathogens, and only on rare occasions is the etiology due to methacillin-resistant Staphylococcus aureus (MRSA). Perinephric and prostatic abscesses have never been reported to occur together. We present a 56-year-old male with poorly controlled diabetes that had recently begun performing daily self-digital rectal examinations, who presented with a three day history of urinary symptoms. The patient had bilateral costovertebral angle tenderness and a boggy, tender, enlarged prostate. Blood and urine cultures showed MRSA. CT scan of the abdomen and pelvis demonstrated right perinephric abscess and prostatic abscess. This case report illustrates the potential for simultaneous perinephric and prostatic abscesses by MRSA.

Key Words: perinephric abscess, prostatic abscess, methacillin-resistant Staphylococcus aureus (MRSA), noninsulin-dependent diabetes mellitus

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Both perinephric and prostatic abscesses may present with protean symptoms and often arise from ascending urinary tract infections. Both abscesses are often caused by uropathogens such as E coli, Proteus species, and Klebsiella species. (1) On rare occasions, the etiology of perinephric or prostatic abscesses can be methacillin-resistant Staphylococcus aureus (MRSA). While persistent metastatic Staphylococcus aureus bacteremia has been described, (2) dual perinephric and prostatic abscesses have never been reported. We report a case of simultaneous perinephric and prostatic abscesses from MRSA.

Case Report

A 56-year-old Caucasian male with past medical history of poorly controlled noninsulin dependent diabetes mellitus (Hb[A.sub.1C] 19%), benign prostatic hypertrophy, hematuria (negative cystoscopy ten years prior) and dyslipidemia presented with a three day history of difficulty urinating, hematuria, fever, chills and low back pain. Before admission, the patient was asymptomatic, had not previously been evaluated for urolithiasis, had not had any known urinary tract catherizations with subsequent antibiotic therapy (eg, quinolones), and two years prior had a negative urine analysis. The patient had recently begun performing daily self-digital rectal examinations due to concern for prostate cancer. He was tachycardic, but afebrile and normotensive. On physical examination, the patient had bilateral costovertebral angle tenderness, right lower quadrant abdominal tenderness, and a boggy, tender, enlarged prostate. The white blood cell (WBC) count was elevated at 17.8 X [10.sup.3] per [micro]L with 80% neutrophils. The patient had elevated serum glucose, but otherwise normal electrolytes. Urine analysis showed significant protein, glucose, large blood, WBCs and 2+ bacteria. The patient was started on ceftriaxone and gentamicin. On the second hospital day, his fever rose to 101[degrees]F, and his antibiotics were changed to piperacillin/tazobactam. Two blood cultures and one urine culture showed MRSA growth on the second day, and the antibiotics were changed to vancomycin and gentamicin. On the third hospital day, a CT scan of the abdomen and pelvis demonstrated a right perinephric abscess and prostatic abscess (Fig.). CT-guided drainage of the perinephric collection was performed on hospital day five; cultures grew MRSA with identical antibiotic sensitivities as previous blood cultures. On hospital day eight, urology performed cystoscopy and transurethral unroofing of the prostatic abscess. Serial CT scans showed gradual resolution of the perinephric and prostatic abscesses. A transthoracic echocardiogram was performed during the hospitalization which showed no valvular vegetations. All repeat blood cultures showed no growth. On hospital day eleven, the patient's percutaneous drain was removed, and the patient was discharged home on a six-week course of vancomycin and rifampin.

Discussion

Staphylococcus aureus bacteremia has the potential to produce metastatic foci that can serve as sources for persistent bacteremia. (2) S aureus is also the most common skin infection. Except for a cystoscopy ten years prior, the patient had no risk factors for MRSA, such as any hospitalizations, surgery, dialysis, residence in long-term care facility, or any indwelling medical device. The bacterial strain had more antibiotic resistance (ciprofloxacin, clindamycin, erythromycin, and tetracycline) than most community-acquired MRSA strains, but was sensitive to gentamicin, rifampin, and vancomycin. This is consistent with previous reports, stating that at least 97% of community-acquired MRSA strains are sensitive to at least the same three antibiotics as in this case. (3) Although this strain has similar resistance and susceptibility patterns as other isolates of community-acquired MRSA in the Cleveland, Ohio, region, it is unclear whether this bacterium is hospital- or community-acquired without further laboratory evaluation.

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This case report also illustrates the potential for metastatic S aureus infections leading to multiple abscesses that can flourish in the setting of uncontrolled diabetes. Diabetes predisposes patients to more severe infections, including perinephric abscesses. (4,5) This is secondary to diabetic neuropathy-induced bladder dysfunction, urologic manipulation, and high glucose concentrations impairing polymorphonuclear leukocytes, (5) all factors that may have contributed to enhanced growth of MRSA in this case.

It is rare for patients to present with S aureus prostatic abscesses. One study found that S aureus prostatic abscesses only occurred in 6 of 99 patients, (6) and there are only two published reports of MRSA prostatic abscesses. (2,7) Instrumentation of the urethra and urinary bladder are risk factors for prostatic abscesses. (6) It is possible that the prior cystoscopy had led to MRSA colonization, but the patient did not become symptomatic until his diabetes was uncontrolled.

Conclusion

Simultaneous perinephric and prostatic abscesses have not been previously reported in the literature. This patient may have been colonized with MRSA from his prior cystoscopy; subsequently, he may have developed a urinary tract infection that expanded into a metastatic S aureus infection that spread to both perinephric and prostatic abscesses in the setting of his uncontrolled diabetes. While unlikely due to the multiple fascial layers of the prostate and an absence of literature of prostatic abscesses among patients who engage in anal intercourse and those who have transrectal ultrasounds of the prostate, it is possible that the self-digital rectal examinations introduced the MRSA from skin colonization. Although the exact pathophysiology of infection is unknown, metastatic S aureus infections can cause high mortality, even when treated correctly. Thus, it is important for clinicians to have heightened awareness of this condition to begin treatment promptly.

References

1. Brook I. Urinary tract and genitor-urinary suppurative infections due to anaerobic bacteria. Int J Urol 2004;11:133-141.

2. Fraser TG, Smith ND, Noskin GA. Persistent methacillin-resistant Staphylococcus aureus bacteremia due to a prostatic abscess. Scand J Infect Dis 2003;35:273-274.

3. Fridkin SK, Hageman JC, Morrison M, et al. Methacillin-resistant Staphylococcus aureus disease in three communities. N Engl J Med 2005;352:1436-1444.

4. Plevin SN, Balodimos MC, Bradley RF. Perinephric abscess in diabetic patients. J Urol 1970;103:538-543.

5. Wheat LJ. Infection and diabetes mellitus. Diabetes Care 1980;3:187-197.

6. Weinberger M, Cytron S, Servadio C, et al. Prostatic abscess in the antibiotic era. Rev Infect Dis 1988;10:239-249.

7. Baker SD, Horger DC, Keane TE. Community-acquired methacillin-resistant Staphylococcus aureus prostatic abscess. Urology 2004;64:808-810.

Aaron A. R. Tobian, MD, PhD, and Scott K. Ober, MD, MBA

From the Department of Medicine, Louis Stokes Cleveland Veterans Affairs Medical Center, Case Western Reserve University, Cleveland, OH.

Reprint requests to Dr. Scott K. Ober, 10701 East Boulevard, 170(W) Cleveland, OH 44106. Email: [e-mail]

A.A.R.T. was supported by National Institutes of Health training grants T32 GM07250.

Accepted September 22, 2006.

RELATED ARTICLE: Key Points

* This case report is novel since there are no previously reported cases of simultaneous perinephric and prostatic abscesses and only two previously reported cases of MRSA prostatic abscesses.

* Due to the high mortality of this condition, even when treated correctly, it is important for clinicians to have heightened awareness of this condition to begin treatment promptly.