Infectious Diseases in Critical Care Medicine

Legionellahas been reported in 2% to 27% of SOT recipients with pneumonia (76–78).

Most common species implicated are Legionella pneumophila and L. micdadei (79,80). A

prodrome of influenza-like symptoms is followed by a sometimes “explosive” pneumonia

with patchy lobular or interstitial infiltrates on chest radiograph. High fever, hypothermia,

abdominal pain, and mental status changes are sometimes seen. Pneumonia is the most

common presentation, but some patients have just fever (74). Other manifestations have also

been described such as liver abscesses, pericarditis, cellulitis, peritonitis, or hemodialysis

fistula infections (81). Infiltrate is usually lobar, butLegionellahas to be included in the

differential diagnosis of lung nodules, cavitating pneumonia, and lung abscess (71).Legionella

infections can be overlooked unless specialized laboratory methodologies (cultured on

selective media, urinary antigen test) are applied routinely on all cases of pneumonia (72).

Routine culture forLegionellain the water supply is recommended in all transplant centers and

ICUs with cases of legionellosis (82). The use of impregnated filter systems may help prevent

nosocomial legionellosis in high-risk patient care areas (83). Late community-acquired

bacterial pneumonias are 10-fold more frequent in cardiac transplant recipients than in the

general population (2.6 cases/100 cardiac transplants) (64). The etiological agents are similar to

those of the general population (S. pneumoniae, Haemophilus influenzae, etc.), with the exception

of lung transplant patients who may suffer recurrent pneumonias caused by

P. aeruginosaorB. cepacia(84).

The frequency ofM. tuberculosisdisease in receptors of solid-organ transplantation in

most developed countries ranges from 1.2% to 6.4%, but in transplant patients living in areas of

high-level endemicity it might reach up to 15% (38,85–87). Although there is a huge regional

variability, in general, SOT incidence is 20 to 74 times higher than in the general population,

with a mortality rate of up to 30%. The most frequent form of acquisition of tuberculosis after

transplantation is the reactivation of latent tuberculosis in patients with previous exposure.

Tuberculosis develops a mean of 9 months after transplantation (0.5–13 months). Risk factors

for early onset are nonrenal transplant, allograft rejection, immunosuppressive therapy with

OKT3 or anti–T cell antibodies, and previous exposure toM. tuberculosis. Clinical presentation

is frequently atypical and diverse, with unsuspected and elusive sites of involvement. A large

series of tuberculosis in transplant recipients described pulmonary involvement in 51% of

patients, extrapulmonary tuberculosis in 16%, and disseminated infection in 33% (38). In lungs,

radiographic appearance may vary between focal or diffuse interstitial infiltrates, nodules,

pleural effusion, or cavitary lesions. Manifestations include fever of unknown origin, allograft

dysfunction, gastrointestinal bleeding, peritonitis, or ulcers. In transplant patients,

M. tuberculosisinfection was also described in skin, muscle, osteoarticular system, CNS,

genitourinary tract, lymph nodes, larynx, adrenal glands, and thyroid (38,88). Ocular lesions

may be an early way to detect dissemination (59). Coinfection with other pathogens is not

Table 3 Probable Etiology of Pneumonia in Relation to the Type and Progression of the Infiltrates

Radiological
pattern

Probable etiology in relation to the type and progression of the infiltrates

Acutea Subacute

Consolidation Bacteria (S. Pneumoniaegram-negative
rods,Legionella,S. aureus) (1–2 wk)
Embolism, atelectasis
Hemorrhage
Acute graft rejection in lung transplant
recipients
CMV (2–3 m or later if prophylaxis)

Aspergillus(30 days),Nocardia, tuberculosis

(9–23 mo), drugs

P. jiroveci, Legionella,HSV, VZV,Toxoplasma

Bronchiolitis obliterans

Interstitial Edema
Transfusions
(Bacteria)

Virus (CMV, influenza, parainfluenza, RSV,
EBV),P. jiroveci, drugs
(Fungi,Nocardia, tuberculosis)
Nodular (Bacteria, edema) Fungi,Nocardia, R. equi, tuberculosis
(P. jiroveci, CMV)

aRequires attention in<24 hours. Less common possibilities are among brackets.

Infections in Organ Transplants in Critical Care 393