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The role of rapid diagnostics in antimicrobial stewardship
WHO recently released its first-ever report on antimicrobial resistance, documenting alarming rates of resistance to antibiotics in every region of the world and predicting "catastrophic consequences" and a "post-antibiotic era," in which these mainstays of medicine are powerless against previously treatable but dangerous infectious diseases. The WHO report follows similar warnings issued by the CDC, the FDA and the White House, and is the most urgent call to action yet to address the growing crisis of antimicrobial resistance.
Overuse of antibiotics is especially prevalent in hospitals, where overprescribing broad-spectrum antibiotics in place of targeted narrow-spectrum therapies has driven an increase in resistant bacteria and the spread of health care-associated infections such as MRSA and Clostridium difficile.
Although many hospitals and clinics have implemented antimicrobial stewardship programs to help reduce antibiotic use, an important and proven strategy is frequently underutilized: the use of rapid diagnostics that can empower health care professionals to identify cases when antibiotics should be prescribed and when they can be withheld.
In many health care settings, diagnostic uncertainty is a limiting factor for optimal antimicrobial stewardship and can lead to the overuse and misuse of antibiotics as clinicians attempt to “second guess†and provide a much-anticipated and often-requested remedy to a sick patient. In fact, rapid tests are available today for many of the conditions that are commonly misdiagnosed or treated empirically during the patient visit.
For example, because throat swab culture can delay diagnosis for 18 to 72 hours, physicians may treat suspected group A streptococcus infection empirically. Because group A strep is the cause in only a limited number of cases of pharyngitis or sore throat cases, there is a need for accurate diagnostics as a key decision-making tool. In the case of respiratory viral diseases such as influenza, infection control measures are important to prevent the spread of disease throughout a health care institution. Misdiagnosis can lead to a lack of implementation of infection control measures, as well as inappropriate treatment with antibiotics, which are ineffective against viral conditions.
James Cottam
Rapid tests also address an inherent problem with the "gold standard" of culture. These culture-based methodologies are sensitive and low cost, but can result in delays of up to 4 days because they rely on growing the bacteria or viruses. During this delay there is a risk for transmission of an antimicrobial-resistant organism to multiple patients. With the advent of newer, more accurate and rapid diagnostics, these time frames can be reduced dramatically. For example, new technologies can dramatically reduce reporting times from several days to only minutes.
In certain parts of Europe, near-patient testing is more widely implemented as part of antimicrobial stewardship, and results clearly demonstrate its effectiveness. In parts of Scandinavia and Switzerland, a simple point-of-care test for the biomarker C-reactive protein (CRP) test is widely used and is helping physicians disseminate, in less than 5 minutes, serious illness from often self-limiting illness like acute bronchitis or other respiratory tract infections, which may not need to be treated by antibiotics. In a 2011 multinational study, point-of-care testing for group A streptococcus and CRP contributed to significant reductions in antibiotic prescribing for respiratory tract infections — as much as 20% in one country.
Along with other interventions such as infection control measures and patient education, rapid testing should be part of the antimicrobial stewardship mix to help ensure that patients get the right antibiotics at the right time, at the right dosage and for the right duration. By identifying the most appropriate therapies, these stewardship programs at international, national and institutional levels are imperative for preserving antibiotic efficacy, improving health care outcomes and reducing health care costs.
WHO. Antimicrobial resistance: global report on surveillance 2014. Available at: www.who.int/drugresistance/documents/surveillancereport/en. Accessed Sept. 27, 2014.