Urinary Actinomyces infection with a urachal remnant

Abstract

Urinary Gram staining is helpful in patients with complicated urinary retention, such as prolonged urinary retention and coexisting ureteral retention disease. If gram-positive rods are observed on urine Gram staining in a patient with urinary tract infection, an anaerobic culture of the urine may be helpful for early diagnosis and treatment of Actinomyces infection.

Background

Actinomyces, a gram-positive anaerobic rod, is generally not detected in routine urinary culture. A major characteristic of Actinomyces infection is mass formation. As the diagnosis is based primarily on clinical and histopathological findings, a biopsy is often required for confirmation. Microbiological diagnosis and treatment are usually initiated on finding gram-positive branching filaments on Gram staining.

Herein, we report a case in which early diagnosis was possible owing to characteristic physical findings and Gram staining.

Case presentation

A man in his 60s without any pre-existing medical conditions presented to our emergency department with periumbilical and lower abdominal distention, abdominal pain and a 2-week history of gradual swelling in the periumbilical region. The patient experienced an urge to urinate; however, he had difficulty passing urine. Three days after abdominal swelling appeared, he presented to our hospital with fever and anorexia, in addition to the above symptoms, and was admitted.

His vital signs on admission were as follows: body temperature, 37.1°C; heart rate, 97 beats/min; blood pressure, 104/60 mm Hg; and respiratory rate, 22 breaths/min.

Investigations

Physical examination revealed marked distention and tenderness extending from the periumbilical region to the lower abdomen (figure 1). Haematology and blood biochemistry showed: white cell count, 31.45×10⁹ (range: 3.3–8.6×10⁹)/L; blood urea nitrogen level, 217 (range: 8.0–20.0) mg/dL; creatinine level, 5.32 (range: 0.65–1.07) mg/dL; sodium level, 129 (range: 138–145) mmol/L; potassium level, 5.7 (range: 3.6–4.8) mmol/L; and C reactive protein level, 19.33 (range: 0.00–0.14) mg/dL. Urinalysis results showed bacteria 3+ and an elevated white cell count (100≤/HF, reference range: <4/HF).

Figure 1.

Photograph of the patient’s abdomen. The periumbilical region and lower abdomen show marked inflation.

Ultrasonography showed significant fluid retention in the bulging umbilical region. A urethral catheter was placed for symptomatic relief, and 1.5 L of urine was drained. Gram staining of the urine (figure 2) showed filamentous gram-positive bacilli. Following urinary drainage, the abdominal distention resolved; however, CT performed for closer examination showed a cord-like structure from the upper bladder border to the umbilical region (figure 3, arrows) and an enlarged prostate gland.

Figure 2.

Gram stain of a urine sample. Gram-positive branching filamentous rods (arrows) and other gram-variable cocci and rods are seen. No sulfur granules are visible (magnification ×1000 (10×100)).

Figure 3.

Abdominal CT scan showing a urachal remnant. An inflamed urachal remnant between the umbilicus and the bladder (arrows).

Differential diagnosis

Based on the ultrasonography and Gram staining findings, urinary retention with an Actinomyces urinary tract infection (UTI) was suspected.

As gram-positive rods were the dominant phenotype observed on Gram staining of the urine specimen, and because of its size and filamentous formation, we ruled out the possibility of other microbial infections such as aspergillosis and fungal microorganisms. As Nocardia can also form gram-positive filamentous rods, Kinyoun staining was performed, which was negative.

Treatment

After submitting the urine for anaerobic culture, we administered empirical treatment with ceftriaxone for 6 days.

Outcome and follow-up

Actinomyces neuii, showing creamy-white, confluent colonies growth, was isolated in the blood and urine culture. The patient was treated with ampicillin, which was continued for 3 days until his fever, abdominal pain and anorexia fully resolved. After his symptoms resolved, he was advised to continue oral amoxicillin for a further 6 months.

Discussion

Our patient with a prolonged urinary retention and a coexisting urachal remnant developed Actinomyces bacteraemia that was detected and successfully treated, preventing the development of an Actinomyces mass. Urachal remnants are an anomaly caused by failure of involution of the urachus during fetal development, resulting in a tubular connection between the urinary bladder and the umbilicus. In this patient, urinary retention in the urachal remnant led to the characteristic appearance of periumbilical distention because of the tubular connection between the bladder and the umbilicus.¹

Actinomyces infections are associated with long-term urinary retention and urachal remnants, both of which were present in our patient.²

Characteristic masses formed due to Actinomyces infection are often misdiagnosed as malignant tumours.³ Overall, <10% of such patients are diagnosed preoperatively, and surgeries are performed in many cases despite their invasiveness.⁴

Actinomyces UTIs require several months of antimicrobial therapy and careful follow-up.⁵ Therefore, early treatment before mass formation benefits patients by preventing unnecessary invasive surgical procedures.

UTIs are commonly caused by gram-negative rods.⁶ An observation of filamentous gram-positive rods in a patient with an UTI indicates an atypical infection and requires additional anaerobic culture of the urine to confirm Actinomyces infection. In our case, Gram staining of the urine allowed early detection and treatment of Actinomyces infection. Therefore, careful examination during Gram staining of the urine is recommended to detect atypical pathogens such as Actinomyces.

Patient’s perspective.

I am grateful for the best and rapid treatment for my serious condition. Please contribute my case fully for development of medicine.

Learning points.

• Urinary Gram staining is useful in patients with complicated urinary retention, such as a prolonged urinary retention and coexisting ureteral retention disease.

• If filamentous gram-positive rods are observed on Gram staining in a patient with a urinary tract infection, anaerobic culture of the urine may be helpful for early diagnosis and treatment of Actinomyces infection.

• In patients with Actinomyces infections, proactive urinary Gram staining can improve patient outcomes by preventing unnecessary procedures and inappropriate treatment due to misdiagnoses.

Ethics statements

Patient consent for publication

Obtained.