Bloodstream Infections, Catheter-Related Infections, and Infective Endocarditis
As other patients requiring intensive care, catheter-related bloodstream infections (CRBSIs) are
a potential threat for severe infection after SOT. In a recent study performed by our group in
HT recipients, CRBSI accounted for 16% of BSI in this population (34). In HT recipients, the
incidence of bloodstream infection is 15.8%. BSI episodes were detected a median of 51 days
after transplantation. The main BSI origins were lower respiratory tract (23%), urinary tract
(20%), and CRBSI (16%). Gram-negative organisms predominated (55.3%), followed by gram-
positive organisms (44.6%). We found a clear relationship between time of onset and some
characteristics of the BSI. During the first month after transplantation, 95% of BSIs were
nosocomially acquired and the main origins were IV catheter (32%), surgical site, and LRT
(18% each). From month 2 to month 6, 70% of the BSIs were nosocomially acquired and the
main origins were UTI and LRT (25% each). After the sixth month, only 22% of the BSI
episodes were nosocomial and the most common portals of entry were LRT (33%), primary
bacteremia (22%), and UTI (17%) (p¼ 0.1). Mortality was 59.2%, with 12.2% directly
attributable to BSI. Independent risk factors for BSI after HT were hemodialysis (OR 6.5;
95% CI 3.2–13), prolonged ICU stay (OR 3.6; 95% CI 1.6–8.1), and viral infection (OR 2.1; 95% CI
1.1–4). BSI was a risk factor for mortality (OR 1.8; 95% CI 1.2–2.8) (34).
CRBSI caused 15% of the febrile episodes of liver transplant recipients in the ICU (9).
Although only 37% of the bacterial infections after liver transplantation occur more than
100 days after transplant, 60% of the cases of primary bacteremia after liver transplantation
occur late (255). The incidence of BSI after OLT is 0.28 episodes/patient. BSI accounted for 36%
of all major infections. Intravascular catheters were the most frequent source and MRSA was
the most frequent pathogen causing BSI. In recent years, a shift toward a higher importance of
gram-negative microorganisms causing bacteremia has been observed (34,256). Gram-negative
CRBSI, mainly if more than one case is detected, should always prompt exclusion of a
nosocomial hazard, such as contamination of the infusate or transmission by health care
workers (257,258).
Seventy percent of catheter-related and all bacteremias due to intra-abdominal infections
occurred90 days, whereas 75% of the bacteremias due to biliary source occurred>90 days
after transplantation. Length of initial posttransplant ICU stay (p¼0.014) and readmission to
the ICU (p¼0.003) were independently significant predictors of bloodstream infections. Up to
40% of the candidemias occurred within 30 days of transplantation and were of unknown
origin, whereas the portal of entry in all candidemias occurring>30 days posttransplant was
known (catheter, hepatic abscess, urinary tract). Mortality in patients with bloodstream
infections was 52% (15/29) vs. 9% (9/101) in patients without bloodstream infections
(p<0.001). In conclusion, intravascular catheters (and not intra-abdominal infections) have
emerged as the most common source of BSI after OLT (259).
In another study, primary (catheter-related) bacteremia (31%; 9 of 29 patients),
pneumonia (24%; 7 of 29 patients), abdominal and/or biliary infections (14%; 4 of 29 patients),
and wound infections (10%; 3 of 29 patients) were the predominant sources of bacteremia (260).
The most important risk factor for CRBSI is the length of catheterization. Most catheters
used in critically ill SOT patients are short termed. These include central venous catheters,
temporary hemodialysis catheters, peripheral venous catheters, and arterial cannulas. The site
of central venous catheterization (internal jugular vein vs. the subclavian vein) does not seem
to have an impact on the incidence of related infections, as long as catheterization is performed
by experienced personnel (261).S. aureusnasal carriage is associated with a higher risk of
bacteremia (63). Active surveillance cultures to detect colonization and implementation of
targeted infection control interventions have proved to be effective in curtailing new
acquisition ofS. aureuscolonization and in decreasing the rate ofS. aureusinfection in this
population (262). Strict adherence to hand hygiene and to prophylactic guidelines may help
reduce the incidence of these infections.
Protothecaspp. are unicellular algae of low virulence that are rarely associated with
human infections. Of nine cases reported in the literature, five had a localized infection and four
had disseminated protothecosis (263). Seven cases were due toP. wickerhamii, and two were due
toP. zopfii. Overall mortality in transplant recipients withProtothecainfections was 88% (7/8).
All four cases of disseminated protothecosis died despite therapy with amphotericin B.
Infections in Organ Transplants in Critical Care 403