Urinary mycobacterium avium presenting as sterile pyuria

Abstract

A 65-year-old healthy woman presented with persistent, asymptomatic sterile pyuria detected by her family physician. While she did not have symptoms, the patient recounts that she has had cloudy urine for years. Cultures of the urine for bacteria showed no growth and no fungi were identified. First-morning urine samples were sent for both tuberculosis and nontuberculosis mycobacterium species testing. The culture grew genotypically identified Mycobaterium avium complex (MAC). Mantoux skin testing was positive. No urological abnormalities were detected by ultrasound and computed tomography (CT) imaging of the urinary tract. IntroductionMAC is classified as a slow-growing nontuberculous mycobacterium (NTM).1 While MAC is ubiquitous in the environment and is the most common disease-causing NTM in humans, there are very few reported cases of MAC infection in the urine and only two reported cases of asymptomatic MAC urine infection. Predisposing factors for NTM infections include defects in host immunity and direct exposure to the NTMs. MAC is ubiquitous in the soil, so those working with soil may be at higher risk of MAC infections.The diagnosis of a MAC urine infection is made with urine culture for MAC and/or polymerase chain reaction (PCR). Direct staining for acid-fast bacilli is considered unreliable. For most patients with a MAC infection, skin Mantoux testing is positive.Testing for MAC infection should be considered for patients with sterile pyuria. While MAC urine infections are not commonly reported, this may reflect how commonly testing for MAC infection is performed rather than how commonly MAC infection occurs. Case reportA 65-year-old woman presented to general urology clinic with persistent, asymptomatic sterile pyuria. This was detected incidentally on routine urinalysis performed by her primary care physician. However, on further questioning, she reported having had cloudy urine for years. Several urinalyses performed by her primary care physician demonstrated abundant neutrophils, but cultures for bacteria and fungus showed no growth and microscopic examination for parasites was negative. She denied any history of dysuria, hematuria, fevers, chills, or other systemic complaints.The patient had a relatively unremarkable medical history with the only medical issues being psoriasis, hypertension, and hypercholesterolemia. She was born in the Czech Republic and emmigrated to Canada at 20 years of age. There was no family history of tuberculosis. She had no antecedent travel or exposure to sick individuals. The patient's physical examination was unremarkable and her repeated urinalyses showed 5-10 leukocytes per high-powered field on urine microscopy. This urine sample again demonstrated no growth on routine culture. Due to the patient's history of repeated sterile pyuria, a first-morning urine was sent for culture for Mycobaterium tuberculosis, Mycobaterium avium, fungus, and examination for parasites. The culture grew genotypically identified Mycobaterium avium complex (MAC).Mantoux skin test ...

Mycobacterium Avium Complex Genitourinary Infections: Case Report and Literature Review

“…Studies question the clinical significance of MAC in the urine as some patients are not treated with antibiotics and managed conservatively [33][34][35]. Like other potential pathogens isolated on cultures, the presence of a positive culture does not necessarily mean true infection: in one large New York hospital over a 3-year period, there were 422 HIVnegative patients with cultures positive for MAC from various body sites.…”