Wikiversity Journal of Medicine/Images of Aerococcus urinae

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Image credits and author of introduction: Mikael Häggström, MD, Sundsvall Regional Hospital
ORCID: 0000-0002-2732-7631
Author correspondence by online form

Author of patient case: Jonatan Mattila, MD, Sundsvall Regional Hospital,
Author correspondence by online form

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Media in this article is on display in Wikipedia in the following article: [https://en.wikipedia.org/wiki/Aerococcus urinae Aerococcus urinae]

Abstract

This is a description of an infection in 73 year old man with multiple comorbidities, with images of Aerococcus urinae from resultant blood cultures, showing their alpha hemolytic and Gram-positive properties.

Plain language summary: Aerococcus urinae is a type of bacteria that can lead to infections in the urinary system. This work describes a 73 year old man who had an infection with Aerococcus urinae. Samples of blood and urine were taken from the patient, and when put on blood cells the bacteria weakly changed the color of the blood cells around them. This result is called alpha hemolysis, and can be seen in Image 1. Adding Gram stain to the bacteria turned them violet, and therefore the bacteria were Gram-positive. This can be seen in microscopy in Image 2. The patient was treated with antibiotics.

Aerococcus urinae

Aerococcus urinae is a relatively new species of bacteria in clinical and microbiological practice, first reported in 1989 and designated as a separate species in 1992.^[1] It can cause urinary tract infections, bacteremia/septicemia and/or endocarditis.^[2] As a urinary tract pathogen, it causes infections predominantly in elderly persons with local or general predisposing conditions.^[3] Aerococcus urinae has been estimated to cause approximately 0.31 - 0.44% of urinary tract infections.^[3]

Patient case

A 73 year old man presented to the emergency department with two days of fatigue, fever and chills. He had a previous history of left arterial cerebral media infarction with expressive aphasia, right side hemiparesis and post-stroke seizures. He suffered from hypertension, atrial fibrillation and aortic stenosis with normal systolic left ventricular function as well as urinary incontinence and prostatic hyperplasia.

In the emergency department he was afebrile and the blood-samples showed a C-reactive protein level of 19 mg/l (normally less than 5^[4] or 6^[5]) and a leukocyte count of 13.7*10⁹/l (normally less than 9.0^[6] or 10.0^[7]). The patient was admitted to the hospital for observation, and after one day on the ward he developed chills and was subfebrile with a tympanic body temperature of 37.6°C (normally up to 37.5°C)^[8]. Blood and urine samples were taken for culture. Microscopy of the blood samples showed gram-positive cocci. The patient received intravenous cefotaxime. After three days all blood samples and urine samples showed growth of gram-positive catalase-negative cocci Aerococcus urinae (Images 1 and 2).

Image 1: Blood agar with alpha hemolytic colonies following culture from the patient's blood samples.

Image 2: Micrograph of the bacteria with Gram stain, showing gram-positive cocci.

Confirmation was done with MALDI TOF mass spectrometry.

During the seven days of inpatient care, inflammatory parameters did not reach more than 61 mg/l for C-reactive protein and 13.7*10⁹/l for leukocyte count. The patient received a cardiac ultrasound due to a systolic murmur, but it did not show any convincing signs of endocarditis.

Written consent was obtained from the patient for this publication.

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References