Mycetoma of the Renal Pelvis Caused by Fusarium Species

A preterm infant, with posterior urethral valves had a mycetoma of the renal pelvis caused by Fusarium species. Prolonged treatment with amphotericin B alone or with flucytosine failed. Combined surgical drainage and medical therapy resulted in full resolution. Case report. The patient was a 1400-g newborn infant born by cesarean section to a 27-year-old woman, gravida 1, para 1, after 28 weeks of gestation. Prenatal ultrasound examination revealed oligohydramnios, dilatation of the bladder, bilateral hydronephrosis, hydroureters and possible posterior urethral valves. These findings were confirmed postnatally along with vesicoureteral reflux. Percutaneous vesicostomy was performed with good urine drainage. After delivery ampicillin and gentamicin were administered for 5 days followed by cloxacillin and rifampin for 7 days because of persistent coagulase-negative Staphylococcus bacteremia at the age of 6 days. On Day 12 urine culture grew Fusarium spp., but blood culture was negative. The Fusarium was identified according to the colony morphology on Sabouraud dextrose and potato dextrose agar and by microscopic examination. Renal ultrasound revealed a mycetoma of the left renal pelvis, without signs of urinary obstruction. Treatment with amphotericin B 1/mg/kg/day was started. After 12 days of treatment rifampin was added, but urine culture remained positive for Fusarium spp. On Day 20 intravesical irrigation with amphotericin B via vesicostomy was attempted for 1 week, but the urine culture and renal ultrasound were unchanged. After 6 weeks of medical treatment with amphotericin B and 2 weeks of combined treatment with flucytosine and amphotericin B, the lesion failed to resolve, and repeated urine cultures were positive. Surgical treatment was deferred initially because of the prematurity, but at this point open pyelotomy of the renal pelvis was performed. A gelatinous substance was drained from the renal pelvis and grew Fusarium spp. Three days later repeated renal ultrasound was normal, and urine cultures were sterile. After 2 weeks the amphotericin B was discontinued. During the entire period blood cultures were negative, and no other focal infection was diagnosed. Follow-up examination 2 months later was unremarkable. Discussion. Renal mycetoma in neonates is uncommon and can result in complete obstruction of the urinary tract. The first sign is usually a flank mass, although urine ascites caused by urinary leak through a fissure in the renal pelvis 1 was described as the first sign in one patient. The diagnosis of renal mycetoma is made by ultrasound examination. In a literature review of renal mycetoma, all published cases were caused by Candida spp., usually Candida albicans.2–5 In one-half to two-thirds of cases there was bilateral involvement, 4 and the obstruction occurred in ∼60%. 2 Candidal bloodstream infection in cases of candidal mycetoma can be as high as 70%, 4 supporting the hypothesis that mycetoma formation is secondary to candidemia rather than to ascending infection. Congenital obstructive uropathy was a risk factor for candidemia and the subsequent mycetoma. 4 Nosocomial infection at the urinary catheter site was a major source of morbidity and mortality in this group. 6 Initial treatment of renal fungus ball is conservative, with surgery as an option. 2, 3, 7 Conservative treatment usually consists of amphotericin B alone or combined with other antifungal agents, administered systemically or injected directly into the bladder. Surgical treatment includes drainage of the fungal mass by percutaneous nephrostomy, open surgery (pyelotomy) or, rarely, nephrectomy. 3 Percutaneous nephrostomy enables good drainage of the renal pelvis and collecting system, irrigation and with an antifungal agent or fragmentation with a guidewire if necessary. In preterm infants, however, this procedure may be hazardous and is reserved only for cases of bilateral fungus ball with evidence of obstructive uropathy. 4, 7 The duration of antifungal medication has traditionally been dictated by the presence of the mycetoma on ultrasound examination and by positivity of urine culture. However, mycetoma may persist long after viable organisms are no longer present. 4 Therefore urine cultures serve as a better guide, and antifungal therapy can be continued for 3 to 6 weeks after the last positive urine culture and stopped before the ultrasonographic findings resolve. 4 Fusarium is recognized as an etiologic agent in localized, superficial or invasive tissue infections in healthy and immunocompromised patients. It causes granulomatous infections in ulcerated, traumatized or burned skin; keratitis after ocular trauma and in contact lens wearers; and onychomycosis. Other less common foreign body-associated Fusarium infections are septic arthritis, osteomyelitis, endophthalmitis and peritonitis. 8 The presence of positive blood culture and more than one site of involvement are indicative of disseminated fusariosis. 8 The optimal treatment regimen for patient with Fusarium infection is not well-established. In vitro studies of antifungal susceptibility have shown that Fusarium may be partially resistant to amphotericin B. However, most authors still recommend it as the drug of choice, often combined with flucytosine or rifampin, and less commonly with ketoconazole or exogenous growth factors. The new triazole, voriconazole, has effectiveness similar to those of itraconazole and amphotericin B. 9 A potential new therapeutic approach to fusariosis is the combination of amphotericin B and azithromycin. 10 This report documents the first case of renal pelvic mycetoma caused by Fusarium spp. in a preterm infant with posterior urethral valves. The successful treatment consisted of a combined medical and surgical approach.