Table 1: Noninvasive testing for obtaining a microbiological diagnosis in solid organ transplant patients with pneumonia

Sample	Laboratory studies
Serum	Blood cultures
	CMV quantitative viral load by PCR
	Aspergillus galactomannen antigen
	Histoplasma, Cryptococcus, Blastomycosisantibody titer
	Histoplasma, Cryptococcus antigen

Urine	Pneumococcal antigen
	Legionella antigen
	Histoplasmaantigen

Nasopharyngeal swab or sputum	Routine culture and Gram stain
	Fungal culture and stain
	AFB culture and stain
	Viral antigen testing for RSV, parainfluenza, influenza, adenovirus

Table 2: Radiographic signs associated with microbiological diagnoses

Finding	Suspected pathogen
Focal consolidation	Bacterial pathogens
"Tree-in-bud opacity"	Atypical pathogens including fungi and mycobacteria
Ground glass opacity	P. jiroveci, viral infections including CMV in at-risk patients
Nodular opacity	Fungi and mycobacteria
"Halo sign"	Aspergillus
Pneumothorax	P. jiroveci

Table 3: Laboratory evaluation of bronchoalveolar lavage (BAL) samples

Essential studies

· Gram stain and quantitative culture

· Fungal evaluation (wet mount stain and culture)

· Mycobacterial evaluation (AFB stain and culture)

· Viral detection and culture (CMV, HSV, Adenovirus, RSV, Parainfluenza virus)

· Gomori methamine silver stain or PCR for P. jiroveci

Optional studies

· Aspergillus galactomannan antigen

· Nocardia culture

· Actinomyces culture

· Toxoplasmosis IFA/DFA

Figure 1

Temporal relationship between infectious etiology and time after transplantation. The risk for bacterial and fungal pneumonia is greatest in the first four weeks and decreases after three months, whereas the risk for CMV infection peaks after the discontinuation of antiviral prophylaxis in at-risk patients. Non-CMV viral infection is typically community acquired and develops more than 6 months after surgery.

Figure 2

Suggested approach to suspected pneumonia in a solid organ transplant recipient. Focal radiographic consolidative changes in conjunction with findings suggestive of bacterial pneumonia lead to empiric antibiotic therapy. Patients presenting > 6 months after transplantation are treated for community acquired pneumonia with observation

while those < 6 months post-procedure are treated for nosocomial infection. All patients

in the latter category, lung transplant recipients, and those non-responsive to empiric therapy should have bronchoscopy performed. Patients with diffuse or nodular opacities should receive empiric treatment but bronchoscopy should be performed to obtain a diagnosis. In patients without a diagnosis after bronchoscopic evaluation, radiologic percutaneous biopsy or surgical lung biopsy should be considered.