# Limitations of inflammatory biomarkers in differentiating patients with fungal pneumonia and bacterial co-infection

## TL;DR

This study finds that inflammatory biomarkers cannot reliably distinguish fungal pneumonia patients with or without bacterial co-infections.

## Contribution

The novel contribution is demonstrating the ineffectiveness of common inflammatory biomarkers in differentiating fungal pneumonia with and without bacterial co-infection.

## Key findings

- No inflammatory biomarkers were statistically significant between fungal pneumonia patients with and without bacterial co-infection.
- Comorbidities like diabetes and chronic inflammatory disease were more common in co-infected patients.
- Unspecified mycosis and pneumocystosis were the most common fungal pneumonia diagnoses.

## Abstract

With the increasing number of fungal infections due to antibiotic use and growing numbers of immunocompromised patients, it has become imperative to understand the nature of these infections. Fungal infections, however, remain largely understudied and underdiagnosed, especially when it comes to co-infections with other organisms. This study aimed to compare inflammatory biomarkers in fungal pneumonia patients with and without bacterial co-infections and analyze the frequencies of the causative bacterial and fungal organisms.

This retrospective study used electronic medical records from patients diagnosed with fungal pneumonia from January 2013 to December 2023. Fungal and bacterial etiologies were identified with International Classification of Diseases-10 codes and summarized with descriptive statistics. Baseline characteristics, comorbidities, and length of stay were analyzed using descriptive statistics and the Chi-squared test. Inflammatory biomarkers, including C-reactive protein, erythrocyte sedimentation rate, procalcitonin, white blood cell count, body temperature, ferritin, and electrolytes, were collected using Current Procedural Terminology codes and compared using Chi-squared test between patients diagnosed with fungal pneumonia alone or with fungal pneumonia and bacterial co-infection.

A total of 1,024 patients were diagnosed with fungal pneumonia. The most common diagnosis among the patients was unspecified mycosis.
Moreover, the most common organism-specific mycotic disease was pneumocystosis. Comorbidities, including diabetes and chronic inflammatory disease, were more common
in patients with co-infection (p < 0.05). None of the inflammatory biomarkers investigated were statistically significant.

Lack of specificity of most fungal organisms responsible for pneumonia highlights the critical lack of specific diagnostic methods for fungal diseases. The results show that inflammatory biomarkers are not significantly different between fungal pneumonia patients with and without bacterial co-infections.