PURPOSE: This study correlates the low prevalence of empyema to the method of pleural fluid culture at our institution. Specifically standard culture in sterile tube grossly underestimates the prevalence of empyema.
METHODS: Our study is a retrospective study of all pleural specimens sent for microbiology at NYDH for years 2008-2009. We reviewed electronic medical records, microbiology and pleural fluid chemistry for patients with empyema. Subsequently we obtained charts for each patient and further data were collected.
RESULTS: Data were obtained over two years for 96 patients. 92 pleural specimens were sent using standard methods and only 2 specimens were sent in blood culture bottles. Seven were sent using both methods. Out of 8 empyemas, 6 were positive by culture, 5 were positive by Gram Stain but only three cases were positive for both gram stain and culture. In our study all cultures grew only one microorganism except one culture done in blood bottles which grew two microorganisms. Of 8 specimens from patients with diagnosis of empyema, 6 specimens were sent using standard method, 1 specimens were sent in only blood culture bottles, and only 1 specimen was sent using both methods.
CONCLUSION: At NYDH the method for culturing pleural fluid is not standardized but predominately involves culture obtained in sterile tubes and not in blood culture bottles. This methodolgy explains the low prevalence of empyema at our hospital of 8.67% compared to published epidemiology ranging from 10 to 25% of parapneumonic effusions. In our study 4 cultures grew Gram positive cocci and two gram negative rods. None of them grew anaerobes.
CLINICAL IMPLICATIONS: Our study correlates our institution’s low prevalence of empyema to the method of culturing pleural fluid. Specifically the conventional method for pleural culture in sterile tube underestimates the prevalence of empyema. We expect that our prevalence of empyema will increase if the pleural fluid specimen will be inoculated in blood culture bottles.
DISCLOSURE: Abhinav Tiwary, No Financial Disclosure Information; No Product/Research Disclosure Information