# A 10-Year Retrospective Study of Bacterial Infections in a Japanese Regional Hospital: The Impact of COVID-19 and an Earthquake

## TL;DR

A 10-year study in a Japanese hospital found that the COVID-19 pandemic and an earthquake reduced some bacterial infections but increased others, like Legionella.

## Contribution

The study reveals unique local trends in bacterial infection patterns influenced by the pandemic and natural disasters, differing from global data.

## Key findings

- Bacterial infections like MRSE and Pseudomonas aeruginosa declined during and after the pandemic.
- Legionella infections increased significantly during and after the pandemic and earthquake.
- Mask usage in Japan may have contributed to reduced transmission of certain bacteria.

## Abstract

Bacterial infections are a leading cause of patient mortality, and antimicrobial resistance continues to pose a growing global health and economic threat. The combined effects of the COVID-19 pandemic and earthquakes may have influenced patterns of bacterial infections. This study analyzed data on antimicrobial-resistant and susceptible bacteria over a 10-year period (2015-2024), encompassing these natural disasters. During the COVID-19 pandemic, the number of positive bacterial cultures declined and continued to decrease following the earthquake. This trend included antimicrobial-resistant bacteria, such as methicillin-resistant Staphylococcus aureus and methicillin-resistant Staphylococcus epidermidis (MRSE). Notably, MRSE cases significantly declined during the pandemic period. In addition, infections caused by drug-sensitive Streptococcus pneumoniae among inpatients and Pseudomonas aeruginosa among outpatients showed a significant reduction, with both continuing to decline in the post-pandemic period. In contrast, Legionella infections significantly increased in both the number and frequency of positive cases, a trend that persisted after the 2024 earthquake. These findings differ from previously reported global data. In Japan, widespread mask usage continued even after the pandemic subsided. The results underscore the importance of improving infection control equipment and promoting individual awareness of infection prevention to reduce the risk of future bacterial infections.