# Analysis of the dynamics of transition from non-colonization to colonization and Staphylococcus aureus bacteremia in hemodialysis patients using Markov models

## TL;DR

This study uses Markov models to analyze how hemodialysis patients transition from non-colonization to Staphylococcus aureus colonization and bacteremia, highlighting risk factors and the need for better management.

## Contribution

The study introduces a Markov model to quantify transition dynamics and risk factors for S. aureus colonization and bacteremia in hemodialysis patients.

## Key findings

- Transition from non-colonization to colonization was three times higher than the reverse.
- Colonized patients were more likely to develop bacteremia (13.9%).
- Previous infection, hospitalization, and antibiotic use increased colonization risk.

## Abstract

Hemodialysis patients are frequently colonized by
Staphylococcus aureus, leading to severe infections with high mortality rates. However, little is known about transition from non-colonization to colonization or bacteremia over time. The aim was to analyze the behavior of
S. aureus colonization, identifying the probability of transition from non-colonized to colonized state or bacteremia, and the influence of some covariates.

The study was conducted in a dialysis unit associated with a high complexity hospital in Medellín between October 2017 and October 2019. An initial measurement was taken to evaluate
S. aureus colonization, and follow-up measurements were performed 2 and 6 months later. Bacteremia evolution was monitored for 12 months. A two-state recurrent continuous-time Markov model was constructed to model transition dynamics from non-colonization to
S. aureus colonization in hemodialysis patients. Subsequently, the model was applied to a third state of bacteremia.

Of 178 patients on hemodialysis, 30.3% were colonized by
S. aureus. Transition intensity from non-colonization to colonization was three times higher (0.21; CI: 0.14-0.29) than from colonization to non-colonization (0.07; CI: 0.05-0.11). The colonization risk increased in patients with previous infections (HR: 2.28; CI: 0.78-6.68), hospitalization (HR: 1.29; CI: 0.56-2.99) and antibiotics consumption (HR: 1.17; CI: 0.53-2.58). Mean non-colonized state duration was 10.9 months, while in the colonized state was 5.2 months. In the 3-state model, it was found that patients colonized were more likely to develop
S. aureus infection (13.9%).

A more likely transition from non-colonization to colonization was found, which increases with factors such as previous infection. In addition, the development of bacteremia was more likely in colonized than in non-colonized patients. These results underline the importance of surveillance and proper management of
S. aureus colonization to prevent serious complications, such as bacteremia, and improve prognosis in this vulnerable population.