Elizabeth Tindal, MD
Overview and Epidemiology
Infections are more common amongst ICU patients, affecting up to 60% in some studies, due to a combination of factors: poorer baseline health status, more severe acute insults, increased exposure to resistant organisms and greater need for indwelling catheters. These infections impact not only patient morbidity and mortality (odds ratio 1.51, p<0.001) but also hospital expenditures. The most commonly encountered infections include catheter-associated urinary tract infections (CAUTI), ventilator-associated pneumonia (VAP), and central-line associated bloodstream infections (CLABSI).
Vincent JL, Rello J, Marshall J, et al. International study of the prevalence and outcomes of infection in intensive care units. JAMA 2009; 302:2323.
Prevention is the key
In the surgical ICU a large percentage of infections that occur are related to indwelling tubes, lines and drains.
-ET tube – VAP
-Foley catheter – UTI
-Central line – CLABSI
-EVD – CSF infection
The single best and highest yield way to reduce these infections is to revisit tube, line and drain indication and need daily. Infection occurrence is distinctly related to duration of time the device is in place.
Evaluation of fever in the ICU
Per a joint task force involving the American College of Critical Care Medicine and the Infectious Diseases Society of America, a fever has been defined as a body temperature greater than 101ºF. However, in immunocompromised patients, a lower threshold may be used. It is also important to remember that patients who are neutropenic, cirrhotic, receiving corticosteroids, or those on continuous renal replacement therapy (CRRT) may not be able to mount a febrile response. A new fever should be evaluated using a chest x-ray, urinalysis with urine culture, blood cultures and manual inspection of all wounds, surgical sites and/or intravascular line sites.
Approach to Common Infections
Catheter-associated urinary tract infections (CAUTI) are defined as a urinary tract infection which develops while a catheter is in place or within 48 hours of its removal. Fever and pyuria are typically present, but patients may also display localizing symptoms (flank/suprapubic discomfort) or nonspecific symptoms like delirium. The most common pathogens involved are E. coli, enterococcus, Pseudomonas or Klebsiella. If possible, the indwelling catheter should be removed or replaced with a new catheter or substituted with intermittent catheterization, based on patient needs at that time. Ideally, a culture should be obtained after catheter removal via a midstream specimen or, if catheterization is still warranted, obtain a specimen after the new catheter is placed. Empiric treatment can be initiated with an agent such as ceftriaxone or zosyn, but should ultimately be chosen based on patient profile (e.g. risk factors for drug resistance, prior culture data). For those patients who have funguria, Candida is most often the offending species. It should be recognized that in hospitalized patients, this is typically a benign process that represents colonization and not infection, however, it difficult to distinguish between the two processes and treatment with an antifungal may be required based on clinical presentation.
Ventilator-associated pneumonia (VAP) is a clinical diagnosis which can be made when a patient who has been mechanically ventilated for over 48 hours develops a new or worsening infiltrate on chest x-ray as well as signs of infection (fever, secretions, leukocytosis). Bronchoalveolar lavage(BAL), via bronchoscopy, with quantitative cultures, is the method of choice in our institution to reduce antibiotic exposure. BAL for VAP diagnosis has not been shown to improve mortality. Decision to proceed with BAL is based on clinical discretion or the clinical pulmonary infection score (CPIS), which combines temperature, white blood cell count, secretions, P:F ratio and chest x-ray findings. A score greater than or equal to 6 has historically been used as a marker that correlates with VAP, and usually warrants a bronchoscopy with BAL and quantitative analysis.
CPIS criteria can be found at: http://www.surgicalcriticalcare.net/Resources/CPIS.php
The most common pathogens involved in VAP are Staph aureus, Pseudomonas aeruginosa, Klebsiella, Enterobacter, Acinetobacter and E. coli. Empiric VAP treatment begins with Vancomycin(Linezolid) and Zosyn(Cefepime or a carbapenem) or a combination that covers MRSA and gram negative organisms(preferably administered immediately after bronchoscopy), and should be narrowed based on culture results. Vancomycin should be bolused at 30 mg/kg actual body weight to establish therapeutic levels more rapidly.
Central-line associated bloodstream infections (CLABSI) is defined as a confirmed bloodstream infection diagnosed more than 48 hours after placement of a central line. The risk of infection is increased in cases where the line is non-tunneled, placed in the femoral vein(especially in the obese), used for TPN or HD, and has multiple lumens. The most common pathogens are coagulase-negative Staph, Staph aureus, Enterococci, Candida and E. coli. 2 peripheral sets of blood cultures should be collected at the time of fever workup. Central catheters should be removed immediately when a patient is hemodynamically unstable or appears to be declining related to a suspected CPABSI. Empiric treatment should include broad spectrum antibiotics, but should be narrowed as soon as patient-specific culture data is available. Wire line exchanges can be used on rare occasion to workup fever. A review updated 12/2017.
Antibiotic Stewardship
Antibiotic stewardship promotes the appropriate use of antibiotics, reduces development of microbial resistance, and decreases the spread of multi-drug resistant infections, all while improving patient outcomes. In the ICU setting, this means that antibiotics should only be initiated when there is a true indication, should be narrowed as soon as sensitivity data is available and should be administered only for as long as appropriate for the underlying infection. An overview of the CDC’s Antibiotic Stewardship program can be found at https://www.cdc.gov/antibiotic-use/healthcare/pdfs/Antibiotic-Stewardship-Final-factsheet_-071216-508.pdf