# Active Surveillance and Polymerase Chain Reaction (PCR) Between Two Passive Surveillance Periods Improve Detection and Characterization of Pleural Empyema: A 20-Year Study in Tijuana, Mexico

## TL;DR

A 20-year study in Tijuana, Mexico, showed that using active surveillance and PCR improved detection and understanding of pleural empyema in children.

## Contribution

The study demonstrates how integrating active surveillance and PCR diagnostics enhances detection and vaccine impact evaluation for pleural empyema.

## Key findings

- Active surveillance with PCR increased detection of pleural empyema cases and identified causative pathogens.
- The study showed the effectiveness of pneumococcal conjugate vaccines (PCV7 and PCV13) in reducing disease burden.
- Molecular diagnostics improved antimicrobial susceptibility profiling and informed better clinical management.

## Abstract

Pleural empyema (PE) surveillance was conducted at Tijuana General Hospital in Tijuana, Mexico, across three distinct periods: passive surveillance (2000-2005), active clinical surveillance with the incorporation of polymerase chain reaction (PCR)-based diagnostics (2005-2018), and a subsequent return to passive surveillance (2022-2024). The implementation of active surveillance coupled with molecular diagnostics substantially improved the detection of PE cases and the identification of causative pathogens, while also enabling the evaluation of the impact of pneumococcal conjugate vaccines (PCVs), including the 7-valent vaccine (PCV7; 2005-2012) and the 13-valent vaccine (PCV13; 2012-2018). This integrated approach provided a more accurate characterization of the etiologic spectrum of PE in children and adolescents, improved antimicrobial susceptibility profiling to better inform clinical management, and generated robust evidence supporting the high effectiveness of PCV13. Collectively, these findings highlight the value of sustained active surveillance and molecular diagnostics in strengthening evidence-based decision-making related to vaccine effectiveness, safety, and potential future vaccine implementation within national immunization programs.