Dynamics of platelet parameters in children with severe community-acquired pneumonia between viral and bacterial infections

Background

Changes in platelet parameters may vary according to the different pathogens. However, little is known about the differences in platelet parameters in children with severe community-acquired pneumonia (CAP) children of viral and bacterial infections.

Methods

This was a single-center retrospective study that included 156 children with severe CAP. Dynamic changes in platelet parameters, including platelet count (PLT), mean platelet volume (MPV), platelet distribution width (PDW) and plateletcrit (PCT), were recorded at 24 h, 48 h, 72 h, and day 7 of admission, as well as at discharge.

Results

At 72 h of admission, PLT in the viral infection group was significantly lower than that in the bacterial infection and bacterial and viral coinfections group. Meanwhile, the curve of changes in PLT (ΔPLT) in the viral infection group was clearly separated from the other two groups at this time point. Receiver operating characteristic (ROC) analysis showed that PLT at 72 h of admission could assist in distinguishing bacterial and viral infections in severe pneumonia children with the area under curve (AUC) value of 0.683 [95% confidence interval (CI): 0.561-0.805, P=0.007]. However, its sensitivity and specificity were not high, at 68% and 65%, respectively.

Conclusions

Although the diagnostic value of platelet parameters in bacterial and viral infection in children with severe CAP is limited, they are still expected to be combined with other indicators to provide a reference for timely treatment.

Targeted next-generation sequencing for pulmonary infection diagnosis in patients unsuitable for bronchoalveolar lavage

Background

Targeted next-generation sequencing (tNGS) has emerged as a rapid diagnostic technology for identifying a wide spectrum of pathogens responsible for pulmonary infections.

Methods

Sputum samples were collected from patients unable or unwilling to undergo bronchoalveolar lavage. These samples underwent tNGS analysis to diagnose pulmonary infections. Retrospective analysis was performed on clinical data, and the clinical efficacy of tNGS was compared to conventional microbiological tests (CMTs).

Results

This study included 209 pediatric and adult patients with confirmed pulmonary infections. tNGS detected 45 potential pathogens, whereas CMTs identified 23 pathogens. The overall microbial detection rate significantly differed between tNGS and CMTs (96.7% vs. 36.8%, p < 0.001). Among the 76 patients with concordant positive results from tNGS and CMTs, 86.8% (66/76) exhibited full or partial agreement. For highly pathogenic and rare/noncolonized microorganisms, tNGS, combined with comprehensive clinical review, directly guided pathogenic diagnosis and antibiotic treatment in 21 patients. This included infections caused by Mycobacterium tuberculosis complex, certain atypical pathogens, Aspergillus, and nontuberculous Mycobacteria. Among the enrolled population, 38.8% (81/209) of patients adjusted their treatment based on tNGS results. Furthermore, tNGS findings unveiled age-specific heterogeneity in pathogen distribution between children and adults.

Conclusion

CMTs often fall short in meeting the diagnostic needs of pulmonary infections. This study highlights how tNGS of sputum samples from patients who cannot or will not undergo bronchoalveolar lavage yield valuable insights into potential pathogens, thereby enhancing the diagnosis of pulmonary infections in specific cases.

Prospective Evaluation of a Rapid Clinical Metagenomics Test for Bacterial Pneumonia

Background

The diagnosis of bacterial pathogens in lower respiratory tract infections (LRI) using conventional culture methods remains challenging and time-consuming.

Objectives

To evaluate the clinical performance of a rapid nanopore-sequencing based metagenomics test for diagnosis of bacterial pathogens in common LRIs through a large-scale prospective study.

Methods

We enrolled 292 hospitalized patients suspected to have LRIs between November 2018 and June 2019 in a single-center, prospective cohort study. Rapid clinical metagenomics test was performed on-site, and the results were compared with those of routine microbiology tests.

Results

171 bronchoalveolar lavage fluid (BAL) and 121 sputum samples were collected from patients with six kinds of LRIs. The turnaround time (from sample registration to result) for the rapid metagenomics test was 6.4 ± 1.4 hours, compared to 94.8 ± 34.9 hours for routine culture. Compared with culture and real-time PCR validation tests, rapid metagenomics achieved 96.6% sensitivity and 88.0% specificity and identified pathogens in 63 out of 161 (39.1%) culture-negative samples. Correlation between enriched anaerobes and lung abscess was observed by Gene Set Enrichment Analysis. Moreover, 38 anaerobic species failed in culture was identified by metagenomics sequencing. The hypothetical impact of metagenomics test proposed antibiotic de-escalation in 34 patients compared to 1 using routine culture.

Conclusions

Rapid clinical metagenomics test improved pathogen detection yield in the diagnosis of LRI. Empirical antimicrobial therapy could be de-escalated if rapid metagenomics test results were hypothetically applied to clinical management.