The Infectious Diseases Society of America recommends pneumococcal urinary antigen testing (UAT) when identifying pneumococcal infections as it would allow for antibiotic de-escalation. However, UAT is not routinely ordered, even in the intensive care unit (ICU). A recent study showed that positive UAT was less frequently associated with resistant organisms but usually did not lead to antibiotic de-escalation, according to data published in Clinical Infectious Diseases.

Investigators performed a retrospective cohort study of adult patients with community-acquired or healthcare-associated pneumonia admitted to 170 US hospitals from 2010 to 2015. Of the 159,894 eligible admissions, 24,757 (15.5%) had UAT performed (ICU, 18.4%; non-ICU: 15.3%). Rates of UAT among hospitals with 100 or more eligible patients varied widely, ranging from 0% to 69%. Compared with patients with a negative UAT result, patients with a positive UAT result were more likely to have a positive Streptococcus pneumoniae culture (25.4% vs 1.9%, P <.001) and less likely to grow other organisms (8.1% vs 11.8%, P <.001). The researchers reported more UAT-positive patients inside the ICU compared with outside the ICU (8.9% vs 6.4%; P <.001). Similar positivity rates were seen in patients with community-acquired pneumonia and those with healthcare-associated pneumonia (7.4% vs 6.7%; P =.06). UAT-positive patients had their broad-spectrum antibiotic coverage narrowed more often than UAT-negative patients and those who did not undergo UAT (38.4% vs 17.0% vs 14.6%, respectively; P <.001); median duration of antibiotic therapy was 3 days, 4 days, and 5 days, respectively (P <.001). Hospital rate of UAT was strongly correlated with de-escalation after a positive test.

The study had several limitations, including its observational design, missed confounders in analyses due to lack of clinical variables in the primarily administrative dataset, and patients being treated with quinolone monotherapy being excluded from the study.

The investigators did conclude that, “UAT appears to be a useful test for identifying patients with pneumonia due to S. pneumoniae.” When patients are stable and receiving broad-spectrum empirical antibiotics, “a positive test appears to signal that antibiotic de-escalation is appropriate.” The investigators also believe that despite UAT being inexpensive, accurate, and rapid, it is currently underused; this represents an important opportunity for antibiotic stewardship. They recommend that broader indications for testing be featured in national guidelines as this may help spread its use nationwide.

Disclosure: A study author declared affiliations with the pharmaceutical industry. Please see the original reference for a full list of author’s disclosures.

Pneumococcal Urinary Antigen Testing Provides Opportunity to Improve Antibiotic Stewardship

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