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. http://dx.doi.org/10.5489/cuaj.3363

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.

Abstract

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.

Introduction

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 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 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

conservatively.

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.

Discussion

Based on its microbiology, clinical, and epidemiologic

characteristics, Mycobacterium avium is classified as a

slow-growing nontuberculous mycobacterium (NTM). It is

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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

-5

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-

7,8

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

0,12

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 4‒20% of patients with pulmonary

-8

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.

0-12

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

0-12

There have been only two reported

urinary frequency.

cases of asymptomatic infection.

0,11

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

0,11

also been used, but is thought to be unreliable.

Most

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

0,12

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

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Yaꢁg ꢀꢃ al.

Al-Muhsen S, Casanova JL. The genetic heterogeneity of mendelian susceptibility to mycobacterial diseases.

J Allergy Clin Immunol 2008;122:1043-51. http://dx.doi.org/10.1016/j.jaci.2008.10.037

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Canada; kjarvi@mtsinai.on.ca

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