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Gardnerella Bacteremia Reported in HIV-Positive Male

Investigators from the University of California San Diego Medical School report on the first case of Gardnerella bacteremia in an HIV-positive male following the placement of a urinary catheter.

In a case study published in Clinical Infectious Diseases, lead investigator, Prerana Bhatia, MD, University of California San Diego Medical School in San Diego California, and her colleagues report on a case of Gardnerella bacteremia in an HIV-positive male following the placement of a urinary catheter.

Gardnerella vaginalis is a gram-positive, rod-shaped anaerobic bacterium that can form biofilms and adhere to epithelial cells. According to the authors, Gardnerella is commonly found in the genitourinary tract of both women and men. Transmission of Gardnerella is not thought to occur through sex and as such, it is not considered a sexually-transmitted infection. Usually, Gardnerella is associated with bacterial vaginosis, an easily treated condition. However, there have been reports, mostly in women, where Gardnerella has caused severe infections, such as bacteremia or brain abscesses.

The patient in the case study was a 51-year old male with AIDS who was admitted to the hospital complaining of headaches, nausea, vomiting, as well as weakness in his right arm, leg, and face. The patient also reported feeling like his bladder was not completely empty, even after urinating. He was not on any antiretroviral drug regimen and presented with normal vital signs. The physicians on the case performed a post-void residual bladder scan which revealed 500 milliliters of urine. Consequently, a urinary catheter placement was attempted 3 times; however, the catheter placement was unsuccessful as the patient reported excruciating pain and voided bloody urine. Later on that same day, a urinary catheter placement was successful and blood cultures were obtained from the patient. Although the patient did not have a fever, laboratory testing showed an increase in white blood cell count from day 1 to day 2, which is indicative of an infection.

After 5 days of incubation of the blood cultures obtained during day 1, 2 anaerobic and 1 aerobic culture grew gram-positive rod-shaped bacteria. The cultures were allowed to grow for 2 additional days, after which time matrix-assisted laser desorption ionization time-of-flight (MALDI-TOF) mass spectrometry was utilized to identify the organism. The organism was identified to be Gardnerella and the oral antibiotic metronidazole was prescribed for a 2-week period. The patient was then evaluated in a urology clinic where the urinary catheter was eventually removed.

The authors note that this case study represents the first reported case of Gardnerella bacteremia due to a urinary catheter placement which demonstrates that even minor procedures can lead to Gardnerella bacteremia. In addition, the authors note that the patient in the study was severely immunocompromised due to his untreated HIV infection which may have put him at a higher risk of acquiring a systemic infection. Furthermore, the authors remark that cases of Gardnerella may be underreported. In previous work, Gardnerella has taken 4 to 15 days for identification which is beyond the time for incubation of blood cultures in most labs. In addition, Gardnerella may be confused with Corynebacterium due to shared morphological characteristics between the 2 bacterial species. Therefore, more specialized analysis, such as MALDI-TOF mass spectrometry is needed to better identify Gardnerella infections.

Samar Mahmoud graduated from Drew University in 2011 with a BA in Biochemistry and Molecular Biology. After two years of working in the industry as a Quality Control Technician for a blood bank, she went back to school and graduated from Montclair State University in 2016 with an MS in Pharmaceutical Biochemistry. She is currently pursuing a PhD in Molecular and Cellular Biology at the University of Massachusetts at Amherst.