Ordering Sputum Cultures in Community Acquired Pneumonia A Cost Conscious Project Morvarid (Marie) Behdin 02/20/19

Introduction The diagnosis of CAP is based on the presence of select clinical features (e.g., cough, fever, sputum production, and pleuritic chest pain) and is supported by imaging of the lung Diagnostic testing for microbial etiology includes blood cultures, sputum cultures, urinary antigens, can aid in diagnosis

Sputum Cultures Expectorated sputum can be submitted for Gram stain and culture, but the utility is currently subject to controversy for the following reasons: Many bacterial species are normal flora/colonizers of the respiratory tract and, although present in respiratory secretions, they may not be responsible for the clinical illness in a patient with pneumonia There are variations in the quality of sputum samples obtained Up 30% of patients with bacterial pneumonia may be unable to produce a sputum specimen, even under optimal conditions The sputum Gram stain has less utility in the diagnosis of atypical pneumonia Initiation of empiric treatment prior to obtaining cultures Overall the rate of pathogen detection varies, some studies indicating diagnostic yields <10% while others indicate rates of 54-86%

IDSA/ATS Guidelines The 2007 IDSA/ATS guidelines recommend Gram stain and culture of a sample of expectorated sputum be obtained only if a good quality sputum can be obtained and if appropriate measures are in place for collection, transport, and processing. Under these circumstances, expectorated sputum specimens are recommended for hospitalized patients with evidence of pneumonia and any of the following: Intensive care unit admission Failure of outpatient antibiotic therapy Cavitary lesions Active alcohol abuse, immunocompromise Severe obstructive or structural lung disease Positive urine antigen test for pneumococcus Positive urine antigen test for Legionella (special culture needed) Pleural effusion

Overall, the strongest indication to obtain further cultures, including sputum cultures is in severe CAP requiring ICU admission and in HAP/VAP

Objective & Methods Objective: To promote evidence-based and cost-conscious care in the inpatient setting by reducing unnecessary laboratory testing Methods: Retrospective chart review of sputum cultures ordered for suspected community acquired pneumonia Reviewed 20 patient admitted to medicine teams A-G, ICU, and family medicine team F Time period: 12/1/2018-2/18/2019 Evaluated appropriateness of sputum testing based on IDSA/ATS guidelines

Results Out of the 20 patients evaluated with suspected/diagnosed CAP, 14 had sputum cultures ordered 10 of the 14 sputum cultures ordered met the IDSA/ATS indications for sputum culture Criteria met: severe sepsis/septic shock (5), immunocompromised (2 chemo, 1 transplant), failure outpatient antibiotics (1), severe underlying obstructive lung disease (1) Criteria not met: sputum culture ordered as part of general sepsis work up when alternative dx suspected (2), otherwise healthy without above criteria met (2) Overall, 28% of patient’s with expectorated sputum specimens collected for CAP did not meet guidelines

Limitations Limited sample size (n=20) Confounders like possible aspiration pneumonia, inhaled steroid use, quality of sputum cultures not accounted for, clinical context Did results of the sputum cultures alter therapy?

Implications With the rising cost of healthcare, it is imperative that we utilize cost conscious approach to medicine and minimize unnecessary tests Each sputum gram stain and culture costs around $167 This means in the small group we evaluated, $668 was spent inappropriately In those who appropriately ordered sputum cultures, did they even utilize those results? Did the results change the management of these patients?

References https://www.thoracic.org/statements/resources/mtpi/idsaat s-cap.pdf https://www.sciencedirect.com/science/article/pii/S119874 3X18308061 https://www.uptodate.com/contents/sputum-cultures-for- the-evaluation-of-bacterial-pneumonia#H6 https://www.uptodate.com/contents/diagnostic-approach- to-community-acquired-pneumonia-in-adults#H9