A Rare Case of a Prostatic Abscess Secondary to a Mycoplasma hominis Infection

Abstract

Mycoplasma hominis is one of the pathogenic organisms that may cause prostatitis with the development of a prostatic abscess in very rare cases. A 57-year-old man presented with lower urinary tract symptoms and low-grade fever. The transabdominal ultrasonography showed prostate enlargement suggesting acute prostatitis. The patient was started on empiric antibacterial therapy with fluoroquinolones. The urine and semen cultures showed no bacterial growth. A few days later, the patient presented again with symptoms progression and acute urinary retention. The transrectal ultrasound revealed diffuse calcifications and intraprostatic fluids. The computed tomography of the abdomen and pelvis showed a large abscess in the prostate with a periprostatic inflammatory reaction. While all bacterial cultures were negative, the multiplex polymerase chain reaction (PCR) test revealed a Mycoplasma hominis infection. The patient was managed with transurethral drainage. After six months of follow-up, the patient was free of symptoms and the repeat PCR study confirmed clearance of the Mycoplasma infection.

Keywords: acute prostatitis; multiplex pcr; mycoplasma hominis; mycoplasma infections; pcr multiplex; prostate abscess; prostate surgery; prostatic abscess; transrectal ultrasound scan; transurethral drainage.

Figure 1. Transabdominal ultrasound examination of the prostate.

Both the axial (A) and the sagittal (B) sections show an inhomogeneous and irregular enlargement of the prostate with an estimated size of 122.1 ml. No abnormalities can be identified in the urinary bladder.

Figure 2. Transrectal ultrasound scan of the prostate.

(A) The section shows a diffuse enlargement of the prostate gland with scattered calcifications. (B) The section shows a hypoechoic area within the prostate gland with a subcapsular leak of fluid. The findings are consistent with a prostatic abscess.

Figure 3. Computed tomography of the abdomen and pelvis with oral and intravenous contrast medium in the venous phase.

The coronal (A), axial (B), and sagittal (C) views of the prostate show diffuse enlargement, scattered calcifications, and a complex abscess structure with intraprostatic fluids. Image C shows the course of the urinary catheter up to the urinary bladder, with the mass of the abscess extending into the small pelvis and pushing the urinary bladder upwards and forwards. Note also the diffuse periprostatic inflammatory reaction in images A and C.

Figure 4. Polymerase chain reaction (PCR) amplification plots.

(A) Multiplex real-time PCR carried out on the prostatic tissue scrapings. Curve 1 depicts the amplified DNA target of Mycoplasma hominis (M. hominis). Curve 2 depicts an amplified internal (endogenous) control, confirming the proper isolation technique pre-PCR. Curve 3 is a flat unamplified negative control confirming the absence of contamination. The window G on the right reveals a threshold cycle (Ct) value of 29.47 for M. hominis only; other microbial DNAs were not detected. (B) Multiplex real-time PCR carried out on the urethral swab. Note that the amplification for M. hominis starts at a Ct value of 23.15 (window E on the right side). (C) Multiplex real-time PCR carried out on the prostatic tissue and urethral swab. All the curves depicted here are amplified targets of known positive control samples indicating a valid probe and PCR reaction.