Infectious Diseases in Critical Care Medicine

23

Infections in Organ Transplants in Critical Care

Patricia Mun ̃oz

Clinical Microbiology and Infectious Diseases Department, Hospital General Universitario, “Gregorio Maran ̃o ́n”,

Madrid, Spain

Almudena Burillo

Clinical Microbiology Department, Hospital Universitario de Mo ́stoles, Madrid, Spain

Emilio Bouza

Clinical Microbiology and Infectious Diseases Department, Hospital General Universitario “Gregorio Maran ̃o ́n”,

Madrid, and CIBER de Enfarmedades Respiratorias (CIBERES), Madrid, Spain

INTRODUCTION
Solid-organ transplant (SOT) recipients may require intensive care unit (ICU) admissions for
different reasons in different moments of their evolution, and infection is one of the most
important of them. Between 5% and 50% transplantation candidates must await trans-
plantation in an ICU and, after the procedure, most of them spend there a mean of four to
seven days for life support (1–6). If the ICU stay is prolonged due to postsurgical
complications, the probability of acquiring a nosocomial infection increases significantly.
Most ICU stays will take place during the period of deepest immunosuppression (7), but
transplant recipients may require readmission to the ICU at any time due to infectious and
noninfectious complications such as severe organ rejection, bleeding, organ dysfunction, etc. In
fact, infections are the most common indication for admissions of transplant recipients in
emergency departments (35%), and severe sepsis (11.7%) is the most common reason for ICU
utilization (8). Figures regarding infections and ICU admissions show that one-half of all
febrile days of liver recipients occur in the ICU, and 87% of these are caused by infections (9).
Antimetabolite immunosuppressive drugs such as mycophenolate mofetil and azathio-
prine are associated with significantly lower maximum temperatures and leukocyte counts
(10). However, in general, the immunosuppression caused by transplantation does not abolish
the inflammatory response, so most transplant recipients with a significant infection will have
fever and most fevers will have an infectious etiology in this setting.
In a multicentric study in Italy, it was shown that most centers are not supported by an
ICU exclusively dedicated to transplantation (11). Accordingly, many of these patients will be
cared by physicians not always familiar with the specific problems posed by the transplant
population. Our aim is to provide information and guidelines regarding most frequently
encountered clinical scenarios relevant to critically ill infected SOT recipients. This chapter
deals with the etiology, approach, and outcome of most common infectious complications
intensive care specialists may find when taking care of SOT recipients. Where no solid data
were available, perspectives based on our own experience and opinion are presented.

INFLUENCE OF THE TYPE OF TRANSPLANTATION AND OF THE TIME AFTER
TRANSPLANTATION
The incidence of infection after a heart transplantation (HT) ranges from 30% to 60% (with a
related mortality of 4–15%) and the rate of infectious episodes per patient is 1.73 in a recent
series (12). Infections are more frequent and severe than those occurring in renal transplant
recipients, but less frequent than those occurring after a liver or a lung transplantation. The
type of SOT and the time after transplantation may be useful clues to the clinician since, unless
unexpected exposure has occurred, there is a timetable according to which different infections
occur post organ transplantation (13,14). According to it, although pneumonia can occur at any