Asymptomatic bacterisputia: Rethinking diagnostic stewardship in pneumonia

Rethinking the “Pan-Culture”: Clinical Impact of Respiratory Culturing in Patients With Low Pretest Probability of Ventilator-Associated Pneumonia

“…For the vast majority of patients in this study, recovery of microorganisms from the respiratory tract likely reflected clinically irrelevant colonization of the respiratory tract, unrelated to the index fever or leukocytosis that prompted culture collection. Our group has previously characterized this scenario as “asymptomatic bacterisputia” and argued that contemporary respiratory culturing practices in critically ill patients may precipitate antibiotic overuse [ 28 ]. Obtaining respiratory cultures to evaluate a new fever or WBC count in mechanically ventilated patients regardless of the presence of signs or symptoms localizing infection to the respiratory tract is commonplace in modern clinical practice and is endorsed in multiple heavily referenced expert guidelines [ 36 , 37 ].…”

“…While the effect size on antimicrobial use observed in this study was modest—1.5 DOT/week, applying to only 12% of screened patients—we expect that the clinical impact of targeting ordering practices for respiratory cultures would be markedly higher in clinical practice for the following reasons: First, patients requiring prolonged mechanical ventilation often have multiple episodes of NATW throughout their clinical course, each of which may precipitate unnecessary antibiotic exposures; and second, our prior published experience suggests that at least 30% of patients excluded from this study because of the presence of radiographic keywords in chest imaging transcripts would not have met diagnostic criteria for pneumonia after chart review and thus could have benefitted from diagnostic stewardship interventions targeting the ordering of respiratory cultures [ 28 , 31 ].…”

“…Positive respiratory cultures inform the diagnostic probability of VAP but are not synonymous with infection, owing to the high burden of bacterial colonization of endotracheal tubing and distal lung parenchyma in critically ill patients [ 23–26 ]. In mechanically ventilated patients, respiratory cultures are frequently ordered indiscriminately and in clinical scenarios where their benefit is uncertain [ 27 , 28 ].…”

Principles of diagnostic stewardship: A practical guide from the Society for Healthcare Epidemiology of America Diagnostic Stewardship Task Force

“…For example, positive urine cultures have lower specificity for UTI diagnosis in the elderly, those with urinary catheters, 32 or young children with bagged or clean-catch samples. 33,34 Several studies have shown that clinicians have a poor understanding of test performance in various populations because as antibiotics are more likely to be prescribed based on urine and respiratory culture results than on the presence of UTI-specific [35][36][37] or pneumonia-specific 38,39 symptoms, respectively. As mentioned in the Test reporting section, several strategies can be implemented in the laboratory to support clinicians to appropriately interpret test results.…”

Leveraging diagnostic stewardship within antimicrobial stewardship programmes

“…This over-reliance on respiratory culturing and misconception that the presence of bacteria is synonymous with infection led Albin et al to coin the term “asymptomatic bacterisputia” as an aid in promoting VAP stewardship efforts. 57 How to decrease detection and treatment of asymptomatic bacterisputia in patients with VAP remains an area with research gaps that need to be addressed before widespread measures can be implemented. 58 …”