Rapid diagnostics are the critical link to improving sepsis care and addressing AMR

The global threat of antimicrobial resistance (AMR)

According to the World Health Organization (WHO), “the persistent failure to develop, manufacture, and distribute effective new antibiotics is further fueling the impact of antimicrobial resistance (AMR)¹¹ and threatens our ability to successfully treat bacterial infections.”^{11, 12} Every year, 700,000 people die of AMR, and if no action is taken, the death toll because of AMR could rise to as many as 10 million, annually by 2050¹² and cause a 3.8% reduction in annual gross domestic product (GDP).¹² This global threat has created room for innovation in the terrain of rapid diagnostic tests to combat the development and spread of drug resistance bacteria. There is a federal challenge/competition, with a prize of $20 million, a joint effort between the National Institutes of Health and the Department of Health and Human Services Office of the Assistant Secretary for Preparedness and Response (ASPR) to address the issue of AMR.¹³

The challenge calls for new, innovative, and novel laboratory diagnostic tests that identify and characterize antibiotic-resistant bacteria, to reduce the unnecessary use of antibiotics, a major cause of antibiotic resistance.¹³ It is important to note that diagnostic tests play an important role in the prevention and inappropriate use of antibiotics because they assist in the selection of the most effective therapy, thereby reducing the risk for antibiotic resistance.¹⁴

Laboratory diagnoses of sepsis causing pathogens

The gold standard for the detection of sepsis-causing pathogens is a blood culture (BC),¹⁵ which requires a higher blood volume for testing, up to 30 ml with multiple culture sets.¹⁵ This has been in use since the inception of early microbiological diagnosis and has served patients with sepsis well, but there are issues that include the delayed resulting of specimens of up to 3 days, cross contamination, and the impact of prior antibiotics use on the likelihood of pathogen detection that could further impact the management of the patient.¹⁵

There are numerous other tests, apart from BC, which are non-specific such as the complete blood count (CBC) that identifies an increase in the white blood cells (WBC), signifying an infection, and a reduction of the WBC may also indicate the individual is at risk of developing an infection.¹⁶ The elevated lactate level is another non-specific method of managing sepsis patients, though lactate levels may also be elevated in other situations such as intense exercise or heart failure.^{16, 17}

Another non-specific test is the C-reactive protein (CRP) that the body produces when there is an inflammation, and several other conditions can cause inflammation, including infections.^{16, 17} Procalcitonin (PCT) is a protein in blood that rises if there is a bacterial infection, but it does not identify the specific bacterial pathogen. Other tests are Prothrombin time and partial thromboplastin time (PT and PTT), platelet count, and d-dimer.^{16, 17}

Rapid diagnostic test (RDT)

The ideal rapid diagnostic test (RDT) would potentially have advantages that include rapid and reliable results, low detection limits, high-throughput testing, and specific organism detection directly from a clinical specimen.¹⁸ There are numerous U.S. Food and Drug Administration (FDA) approved molecular diagnostic tests for detecting sepsis causing pathogens,¹⁸ some are culture independent tests such as the magnetic resonance (T2MR), metagenomic shotgun sequencing methods, and nucleic acid amplification platforms. There are also the culture dependent platforms or post-culture, meaning it relies on the BC result before it can be tested on such a diagnostic platform such as MALDI-TOF MS, Real-time multiplex PCR, and in situ hybridization.¹⁸ Culture is the standard for pathogen detection, but in recent times, culture independent diagnostic tests are increasingly used due to their advantages such as rapid detection of organisms, which is critical to clinical decision making.¹⁹

The newer rapid diagnostic tests (RDT) could shorten the time to the detection of pathogens, and this could potentially lead to faster initiation of appropriate and targeted therapy,^{19, 20, 21} shortening the time of unnecessarydrugs,¹⁹ thereby, reducing the time of exposure to ineffective medicine. This may reduce the chances of developing AMR.^{19, 20, 21} All these could have an impact on the rate of mortality, length of stay (LOS) in the hospital, and a reduction in cost of both drugs and bed occupancy per patient.^{19, 20, 21}

Aparna Ahuja, MD, PGDip Hosp Mgment, DCH&FW, IFCAP, Chief Medical Officer at T2 Biosystems

Temitayo Famoroti, MD, MPH, MMed, Senior Medical Affairs Specialist, T2 Biosystems

Muhsen Alkurdi, BSMG, ICBB, Medical Affairs Manager at T2 Biosystems

References

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