891. Does Bacterial Infection Cause Post-Obstructive Pneumonia (POP)?
Session: Poster Abstract Session: Respiratory Infections
Friday, October 4, 2013
Room: The Moscone Center: Poster Hall C
Background: A pulmonary infiltrate distal to a tumor of the lung is called POP. Patients (pt) with POP are generally treated for bacterial infection with little evidence to support this approach. There is remarkably insufficient literature on this common clinical problem. 

Methods: For 14 months we prospectively studied every pt admitted for a syndrome consistent with community acquired pneumonia (CAP). For the present study we selected pt whose imaging revealed a pulmonary infiltrate distal to a lung mass. Symptoms and signs were recorded. Nearly all pt had cultures of blood and sputum, urine antigen tests for Legionella and pneumococcus, PCR for 15 respiratory viruses (Biofire, Salt Lake City, UT) and serum procalcitonin (PCT) (Biomérieux, Durham, NC).  

Results: 22 pt, all male, met entrance criteria; in every case POP was included as an admission diagnosis. Mean duration of symptoms was 19d (range 1-60, median 14) prior to admission. Of 22 pt, 8 had subjective fever, 20 increased cough and 13 increased sputum. Only 8 (36.4%) had fever (temp >99.4 F) during the first 24 hr in hospital. Mean WBC was 12,305 (range 4,500 to 28,300 median 11,050). Mean PORT score was 101.2. A bacterial pathogen was identified by blood culture in 2 pt; none had positive sputum culture or urine antigen for pneumococcus or Legionella. PCR identified a respiratory virus in 4/19 pt, identifying coronavirus in 3 and rhinovirus in 1. Mean and median PCT were 1.35 and 0.19, respectively. PCT was <0.1 (strongly opposes bacterial infection) in 6, 0.1 to <0.25 (indeterminate) in 6, and >0.25 (suggests bacterial infection) in 10. All pt were treated empirically with antibiotics; by the 5th hospital day, 14 felt subjectively better, and mean WBC count fell to 10,620. 

Conclusion: We systematically studied pt with POP, a diagnosis that regularly leads to antibiotic treatment. Clinical findings, generally negative bacteriology and PCT <.25 in 12 (54.5%) pt or PCT <.1 in 6 (27.3%) pt suggest that a substantial proportion of patients with POP do not have bacterial infection. Renewed attempts are indicated to determine whether infiltrates in POP patients are attributable to bacterial infection.

Daniel Musher, MD, FIDSA1,2, Rahul Sampath, MD1,2, Carlo Zuno, MD1,2, Michael Abers, MD2, Barcleigh Sandvall, MD2, Nancy Logan1 and Charles Stager, PhD1,2, (1)Michael E. Debakey VA Medical Center, Houston, TX, (2)Baylor College of Medicine, Houston, TX

Disclosures:

D. Musher, None

R. Sampath, None

C. Zuno, None

M. Abers, None

B. Sandvall, None

N. Logan, None

C. Stager, None

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