# Electrolyte Concentration in Urine and Urinary Infection—Is There Any Relation?

## TL;DR

This study investigates whether ion concentrations in urine are linked to urinary tract infections, finding a possible connection with calcium levels.

## Contribution

The study explores the relationship between urinary ion concentrations and UTIs, revealing a novel potential role for calcium in bacterial proliferation.

## Key findings

- Higher calcium concentrations in urine may facilitate the growth of Gram-negative bacteria.
- Sodium, potassium, chloride, and magnesium concentrations do not appear to influence UTIs.
- Gram-negative bacteria do not proliferate in low-calcium environments.

## Abstract

Background: Sodium, potassium, chloride, calcium, and magnesium in urine are useful biomarkers and are commonly evaluated in patients with different conditions. Urinary tract infections are among the most common diseases worldwide. However, their treatment poses significant challenges, particularly in hospitals, primarily due to antibiotic resistance and recurrence. Objectives: To evaluate the relationship between ion concentrations in urine and the presence of infection. Methods: A total of 175 random urine samples were collected from patients who had a request for urine culture at the Cova da Beira University Hospital Centre in Portugal. In vitro contamination was also conducted, in which ten negative urine cultures were contaminated with an Escherichia coli strain to evaluate the direct effect of its presence on the concentration of the ions. Results: In total, 61 samples were found to be positive, following a consensual quantitative definition. For Ca, there was a significant association between its concentrations in positive and negative cultures. In ten negative urine cultures experimentally contaminated with an Escherichia coli strain, bacterial growth did not seem to affect the concentration of ions. In vitro contaminated samples were also inoculated on MacConkey agar and incubated. The results showed that Gram-negative bacteria do not seem to proliferate in environments with low Ca concentrations. Conclusions: The presence of higher concentrations of Ca may facilitate the multiplication of Gram-negative bacteria, which can potentially result in depletion of Ca in vivo to putatively potentiate an inflammatory response. The concentration of Na, K, Cl, and Mg does not seem to have any relationship with UTIs.