residents’ room  
Urinary mycobacterium avium presenting as sterile pyuria  
Kai Yang; Mary Samplaski, MD; Tony Mazzulli, MD; Kirk Lo, MD; Ethan Grober, MD; Keith Allen Jarvi, MD  
Faculty of Medicine, University of Toronto, Toronto, ON, Canada; Department of Urology, University of Southern California, CA, U.S.; Department of Laboratory Medicine and Pathobiology, University of  
Toronto, Toronto, ON, Canada; Department of Surgery, University of Toronto, Toronto, ON, Canada  
Cite as: Can Urol Assoc J 2016;10(5-6):E186-8.  
Published online May 12, 2016.  
Case report  
A 65-year-old woman presented to general urology clin-  
ic with persistent, asymptomatic sterile pyuria. This was  
detected incidentally on routine urinalysis performed by  
her primary care physician. However, on further question-  
ing, she reported having had cloudy urine for years. Several  
urinalyses performed by her primary care physician demon-  
strated 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 his-  
tory with the only medical issues being psoriasis, hyperten-  
sion, 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.  
A 65-year-old healthy woman presented with persistent, asymptom-  
atic 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 uro-  
logical abnormalities were detected by ultrasound and computed  
tomography (CT) imaging of the urinary tract.  
MAC is classified as a slow-growing nontuberculous myco-  
bacterium (NTM). While MAC is ubiquitous in the environ-  
The patient’s physical examination was unremarkable  
and her repeated urinalyses showed 510 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 was performed and read as positive  
with 17 mm of induration. Ultrasound and computed tom-  
ography (CT) scan of the abdomen and pelvis demonstrated  
no abnormalities. Consideration was given to medical treat-  
ment of the MAC, but given that the patient was completely  
asymptomatic, the consensus decision was to manage her  
ment 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 infec-  
tions 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 test-  
ing 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 com-  
monly MAC infection occurs.  
Based on its microbiology, clinical, and epidemiologic  
characteristics, Mycobacterium avium is classified as a  
slow-growing nontuberculous mycobacterium (NTM). It is  
CUAJ • May-June 2016 • Volume 10, Issues 5-6  
2016 Canadian Urological Association  
Gꢀꢁꢂꢃꢄuꢅꢂꢁaꢅy mAC ꢂꢁfꢀcꢃꢂꢄꢁ  
one of the most common nontuberculous species causing  
human disease in the U.S. The precise frequency of disease  
due to Mycobacterium avium is unknown because disease  
reporting is not mandatory.  
manipulation of the urinary tract system, trauma with sub-  
sequent contamination, or hematogenous or lymphatic  
spread from other organs, such as lungs. Our patient had  
no signs/symptoms suggesting infection of other organ sys-  
tems or any of the other risk factors.  
As a nontuberculous mycobacterium, Mycobacterium  
avium is ubiquitous in the environment and it has been  
recovered from water and soil, as well as domestic and wild  
The treatment for genitourinary MAC infection is not  
well-defined and the reported cases have been treated on  
an individualized basis. Treatments reported in previous  
reports have included expectant management, medical  
treatment, and surgical treatment. Medical management of  
mycobacterium infection, such as isoniazid, streptomycin,  
rifampin, and ethambutol, are oftentimes ineffective against  
MAC infection, but may be used depending on culture and  
animals. Environmentally and clinically isolated MACs  
generally belong to different serotypes. However, myco-  
bacteria can become aerosolized from aqueous sources, and  
the strains that are more easily aerosolized are phenotypic-  
ally the same as the ones that cause pulmonary infections.  
Isolates similar or identical to clinically isolated strains have  
also been recovered from naturally occurring surface water,  
hot tubs, and piped hot water systems. Currently, there are  
no convincing data demonstrating human-to-human trans-  
mission. Thus, the concept prevails that these organisms are  
in vitro susceptibility results.  
Due to the asymptomatic  
nature of our patient, as well as her normal imaging, she  
was treated with conservative management.  
Genitourinary tract infections due to Mycobacteria  
tuberculosis are comparatively more common than NTM  
infections. An estimated 420% of patients with pulmonary  
acquired from the environment.  
Risk factors for nontuberculous mycobacterial disease  
include defects in the host immune response due to inher-  
ited or acquired conditions, particularly those that affect  
the Th1 cell and macrophage pathways, and exposure to  
environmental NTMs; repeated surgical interventions in  
the genitourinary tract could also introduce environmental  
tuberculosis develop genitourinary tract involvement. The  
clinical presentation of genitourinary tuberculosis infection  
and NTM infection generally both manifest with lower urin-  
ary tract symptoms. Based on Huang et al, patients with NTM  
infection are more likely to report constitutional symptoms,  
such as fever and leukocytosis, and shorter duration of the  
symptoms (one month or less) than those with tuberculosis  
infections, which typically last up to three months.11  
MAC. There was no evidence that our patient had any  
recognized risk factors for MAC infection, nor any signs of  
being immune-compromised.  
Unlike genitourinary tuberculosis, genitourinary infec-  
tions caused by MAC are relatively rare and only a few cases  
This case study is one of the only reports of MAC infection  
in the urine of an immune-competent individual. Despite the  
report of other NTM species in genitourinary organs, such as  
prostate and epididymis, detection of MAC was only reported  
in urine samples. Although rare, genitourinary MAC infections  
should be considered in the differential diagnosis of sterile  
pyuria, especially in patients who are resistant to conventional  
antibiotic treatment. At present, treatment is generally indi-  
vidualized and may include surveillance, as with our patient.  
have been reported.  
To date, published reports of MAC  
infection of the genitourinary tract system have only reported  
its detection in urine samples, while other NTMs have been  
detected in prostate and epididymis biopsy samples. In  
nearly all reported cases, patients have symptoms of infec-  
tion similar to other conventional bacterial genitourinary  
infections, including fever, dysuria, hematuria, urgency, and  
There have been only two reported  
urinary frequency.  
cases of asymptomatic infection.  
Competing interests: Dr. Mazzulli has been an Advisory Board member for Merck, Paladin, and  
Roche; a Speakers’ Bureau member for Merck and Paladin; and has participated in clinical trials  
for Qvella. Dr. Grober has been an Advisory Board and Speakers’ Bureau member for Eli Lilly,  
Merck, and Paladin; has received grants/honoraria from Paladin; and holds investments in MHB  
Labs. Dr. Jarvi has been an Advisory Board member for Eli Lilly; has received grants/honoraria  
from Allergan; and has participated in clinical trials for Allergan. The remaining authors declare no  
competing financial or personal interests.  
Detection of MAC through urine culture and/or polymer-  
ase chain reaction (PCR) is most commonly used to establish  
the diagnosis, though direct staining for acid-fast bacilli has  
also been used, but is thought to be unreliable.  
reported MAC-infected patients had a positive Mantoux test  
and persistent pyuria. In some studies, histological study was  
performed on prostate tissue and caseating granulomatous  
lesions were found.  
However, due to the invasiveness of  
This paper has been peer-reviewed.  
tissue biopsy, this investigation is not regularly performed  
in other studies. Other radiological urinary tract infection  
findings, such as hydronephrosis and multiloculated renal  
cysts, were only reported by Hung et al.  
The etiology of MAC infection in the genitourinary tract  
system is poorly understood. Potential sources of MAC infec-  
tion include introduction of the organism through surgical  
CUAJ • May-June 2016 • Volume 10, Issues 5-6  
Yaꢁg ꢀꢃ al.  
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Correspondence: Dr. Keith Allen Jarvi, Department of Surgery, University of Toronto, Toronto, ON,  
CUAJ • May-June 2016 • Volume 10, Issues 5-6