Rapid and Sensitive Identification of Bacterial Infection and Bacteria Gram Types in Pleural Fluid of Children

Rapid and sensitive identification of pleural and peritoneal infections by droplet digital PCR

Pleural and peritoneal infections cause substantial morbidity and mortality. Traditional diagnostic methods rely on the cultivation of clinical samples, which usually takes days to obtain report and holds a low detection sensitivity. In this study, we evaluated a 5-fluorescent-channel droplet digital PCR (ddPCR) system and 5 assay panels for culture-independent rapid pathogen detections directly from pleural and peritoneal fluid samples. Traditional culture of the same sample was used as reference. A total of 40 pleural fluid samples and 19 peritoneal fluid samples were tested in this study. Twenty-five positives including 4 polymicrobial infections by culture and 26 positives including 11 polymicrobial infections by ddPCR were detected for pleural fluid samples; 14 positives including 2 polymicrobial infections by culture and 15 positives including 3 polymicrobial infections by ddPCR were detected for peritoneal fluid samples. Klebsiella pneumoniae was the most common bacterium detected both in pleural and in peritoneal fluid samples. The sensitivity of the ddPCR assay for pleural and peritoneal fluid samples was 96% (95% confidence interval (CI) = 79.65 to 99.90%) and 92.86% (95% CI = 66.13 to 99.82%), respectively. The turnaround time of the ddPCR assay was approximately 3 h comparing with 38.30 ± 22.44 h for culture-based identifications. Our results demonstrated that the ddPCR assay is a rapid and sensitive method for identifying pathogens responsible for pleural and peritoneal infections and would be a promising approach for early diagnosis and optimizing treatment of infections.

Detection of the major bacterial pathogens among children suffering from empyema in Ahvaz city, Iran

Introduction

Empyema is one of the important causes of pediatric hospital admissions.

Aim

In this study, we had investigated the frequency rates of S aureus, S pneumoniae, H influenzae, and P aeruginosa using PCR and bacterial culture among children suffering from empyema in Ahvaz city, Iran.

Methods

This was a descriptive study conducted on the patients hospitalized in ICUs of two teaching Hospitals of Ahvaz, Iran, between March and September 2018 on 105 pleural fluid (PF) samples of the children less than 16 years of age with the diagnosis of empyema thoracis. These specimens were inoculated on the bacterial culture media and identified using biochemical characteristics. Then, the existence of the four pathogens mentioned above was evaluated using PCR method.

Result

In this study, these bacteria agents were identified in 81 (77.14%) and 30 (28.57%) cases using the PCR assay and bacterial culture, respectively. Moreover, the PCR assay identified the infectious agents in 51 (68%) of PFs where the culture method failed. S pneumoniae (63 cases) was recognized as the most common pathogen, followed by P aeruginosa(19 cases), S aureus(15 cases), and H influenzae (9 cases) using the bacterial culture and PCR. Co‐infections were detected in 21 samples (20%) using PCR and one sample using the bacterial culture (P aeruginosa and S pneumoniae).

Conclusion

In this study, we found the higher frequencies of these microorganisms using PCR than culture. In addition, we showed that PCR was a sensitive and accurate method that unaffected by antibiotic therapy and could detect well co‐infections.