Repeat Molecular Testing for Respiratory Pathogens: Diagnostic Gain or Diminishing Returns?

Post-COVID-19 pandemic changes in pertussis incidence among patients with acute respiratory tract infections in Zhejiang, China

Background

Previous studies have compared the incidence of pertussis before and during the COVID-19 pandemic, finding that public health measures related to COVID-19 contributed to a temporary decline in reported pertussis cases during the pandemic. However, the post-pandemic period has seen a resurgence in respiratory infections, influenced by relaxed health measures and decreased public vigilance. This study investigates the epidemiological dynamics of pertussis among patients with acute respiratory tract infections (ARTI) in Zhejiang Province, China, providing essential reference information for ongoing public health strategies.

Methods

This study analyzed multicenter data from January 2023 to May 2024, involving 8,560 patients with ARTI from three hospitals in Zhejiang Province. Inclusion criteria included patients who presented with cough symptoms and were clinically diagnosed with either acute upper respiratory tract infections (URTI) or acute lower respiratory tract infections (LRTI), and who had undergone at least one Bordetella pertussis DNA test. The study analyzed the epidemiological changes of pertussis positivity rates and their associations with time, age, gender, and diagnosis types (URTI and LRTI).

Results

From January 2023 to May 2024, the positivity rate and testing number for pertussis among patients with ARTI generally showed a gradual increasing pattern. In March 2024, the positivity rate reached its peak at 31.58%, followed by a weekly decline. The overall positivity rate was 23.59%, with no significant differences observed between genders. Pertussis incidence was higher in patients with LRTI (24.49%) compared to those with URTI (18.63%, OR = 1.40, 95% CI: 1.20-1.63, p < 0.001) and in outpatients (25.32%) compared to inpatients (6.09%, OR = 4.17, 95% CI: 3.07-5.64, p < 0.001). According to a generalized additive model analysis, there was a wave-shaped, non-linear relationship between age and pertussis incidence, with a relatively high rate observed in the 5 to 17 age group, peaking at age 10 (33.85%). Additionally, the impact of age, patient type, and diagnosis type on the pertussis infection rate varied across different age groups.

Conclusion

After the COVID-19 pandemic, the positivity rate of pertussis in Zhejiang Province peaked in early 2024 and then showed a declining pattern. Children and adolescents were particularly affected, emphasizing the need for enhanced vaccination and public health interventions in this population.

Diagnostic Stewardship for Multiplex Respiratory Testing: What We Know and What Needs to Be Done

Syndromic respiratory panels are now widely available in clinical microbiology laboratories and health care institutions. These panels can rapidly diagnose infections and detect antimicrobial resistance genes allowing for more rapid therapeutic optimization compared to standard microbiology approaches. However, given reimbursement concerns and limitations of multiplex molecular testing and results interpretation, maximum clinical utility and positive clinical outcomes depend on active diagnostic stewardship. Here, the authors review clinical outcomes of both upper and lower respiratory panels and present diagnostic stewardship strategies for optimal use of respiratory panels.

Effective Approaches to Diagnostic Stewardship of Syndromic Molecular Panels

BACKGROUND

Syndromic molecular panels for the diagnosis of gastroenteritis, meningitis/encephalitis, and pneumonia are becoming routinely used for patient care throughout the world.

CONTENT

These rapid, sample-to-answer assays have great potential to improve patient care, infection control, and antimicrobial stewardship. However, diagnostic stewardship is essential for their optimal use and accuracy, and interventions can be applied at all phases of the diagnostic process.

SUMMARY

The aim of this review article is to describe effective approaches to diagnostic stewardship for syndromic molecular panels to ensure appropriate test utilization and quality assured results.

Roles for Pathogen Interference in Influenza Vaccination, with Implications to Vaccine Effectiveness (VE) and Attribution of Influenza Deaths

Pathogen interference is the ability of one pathogen to alter the course and clinical outcomes of infection by another. With up to 3000 species of human pathogens the potential combinations are vast. These combinations operate within further immune complexity induced by infection with multiple persistent pathogens, and by the role which the human microbiome plays in maintaining health, immune function, and resistance to infection. All the above are further complicated by malnutrition in children and the elderly. Influenza vaccination offers a measure of protection for elderly individuals subsequently infected with influenza. However, all vaccines induce both specific and non-specific effects. The specific effects involve stimulation of humoral and cellular immunity, while the nonspecific effects are far more nuanced including changes in gene expression patterns and production of small RNAs which contribute to pathogen interference. Little is known about the outcomes of vaccinated elderly not subsequently infected with influenza but infected with multiple other non-influenza winter pathogens. In this review we propose that in certain years the specific antigen mix in the seasonal influenza vaccine inadvertently increases the risk of infection from other non-influenza pathogens. The possibility that vaccination could upset the pathogen balance, and that the timing of vaccination relative to the pathogen balance was critical to success, was proposed in 2010 but was seemingly ignored. Persons vaccinated early in the winter are more likely to experience higher pathogen interference. Implications to the estimation of vaccine effectiveness and influenza deaths are discussed.

Molecular Diagnosis of Pneumonia (Including Multiplex Panels)

Background

Pneumonia is a common illness, accounting for a staggering amount of worldwide morbidity and mortality. The diagnosis of pneumonia is challenging given the variety of responsible pathogens. Diagnostic testing for bacterial pneumonia has traditionally relied on time-consuming culture-based methods, though recently multiplexed molecular approaches have been described. Multiplexed molecular assays for pneumonia have the potential to provide broad diagnostic information in a rapid timeframe. Much has yet to be learned about these assays regarding analytical performance, potential impact, and optimal implementation strategy.

Content

Herein we provide a summary of what is known and what has yet to be learned about multiplexed molecular pneumonia assays. We provide a comparison of the different commercially available assays and summarize the most current performance data for each. We further describe outcome data and lessons learned from those who have implemented these assays worldwide. Finally, based on the current state of performance and outcome data, we provide informed strategies and considerations for laboratories contemplating implementation.

Summary

Multiplexed molecular assays for the diagnosis of pneumonia boast high accuracy though the diagnostic information gained from these assays is inherently different from culture and must be interpreted in cultural context. Despite this, these assays can be powerful and effective diagnostic tools with a potential to positively impact patient care. The extent to which this is realized varies from setting to setting, though is dependent on thoughtful implementation and a focus on delivering clear, rapid, and actionable results that can be interpreted in the appropriate context.

Impact of FilmArray™ Respiratory Panel testing on the clinical management of pediatric bone marrow transplant patients

Viral respiratory tract infections cause significant morbidity in bone marrow transplant (BMT) patients. Speed and sensitivity of the FilmArray™ Respiratory Panel (FA-RP) can improve care but may prompt inappropriate testing. Studies describing FA-RP use in pediatric BMT patients are limited; we investigated FA-RP use, results, and clinical management to evaluate clinical significance of testing in pediatric BMT patients. Retrospective analysis of 671 respiratory specimens from 204 unique BMT patients between 01/01/2016 and 01/01/2019 was performed. Age, underlying diagnoses, FA-RP result, reason for FA-RP, and symptoms were abstracted. FA-RP impact on antimicrobial management, scheduled procedures, infection control measures, and hospital admission/discharge were investigated. Impacts of repeat testing were evaluated. Two hundred sixty-nine out of 671 specimens (40%) tested positive; human rhinovirus/enterovirus (hRV/hEV) was the most common (161/269, 60%). The primary reason for FA-RP was URI symptoms (402/671, 60%) with 54% testing positive. One hundred twenty-two out of 671 (18.2%) specimens were from asymptomatic patients; 14 (11.4%) tested positive. FA-RP informed antiviral initiation in 7/19 (36.8%), 7/8 (87.5%), and 5/30 (16.7%) of RSV, influenza, and human parainfluenza cases, respectively. In 11 cases, FA-RP informed azithromycin and ceftriaxone initiation, continuation, or discontinuation. BMT was delayed for three positives (two RSV, one hRV/hEV). In 22 instances, negative FA-RP cleared patients for BMT. In 70% of cases, repeats offered no new clinical information; all negative-to-positive cases had new or worsening respiratory symptoms. FA-RP was ordered on symptomatic and asymptomatic patients, provided rapid diagnosis in > 50% of symptomatic patients, and informed infection control measures for all inpatients and antiviral initiation in > 80% of influenza cases.