infection control & hospital epidemiology
november 2015, vol. 36, no. 11
original article
Catheter-Associated Urinary Tract Infections in Intensive Care Unit Patients Rudy Tedja, DO;1 Jean Wentink, RN, MPH;3 John C O’Horo, MD;2 Rodney Thompson, MD;2,3 Priya Sampathkumar, MD2,3
objective. To delineate the epidemiology of catheter-associated urinary tract infections (CAUTIs) and to better understand the value of urine cultures for evaluation of fever in the intensive care unit (ICU) setting design. setting. patients.
Two-year retrospective review (2012–2013) A single tertiary center with 1,200 hospital beds and 158 adult ICU beds ICU patients with a CAUTI event
methods. The cohort was identified from a prospective infection prevention database. Charts were reviewed to characterize the patients. CAUTI rates and device utilization ratio (DUR) were calculated. Clinical outcomes were recorded. results. A total of 105 CAUTIs were identified using the National Health and Safety Network (NHSN) definition. Fever was the primary indication for obtaining urine culture in 102 patients (97%). Of these 105 patients, 51 (51%) had an alternative infection to explain the fever, with pneumonia (55%) being the most common followed by bloodstream infection (22%). A total of 18 patients (18%) had fever due to noninfectious cause, and 32 patients (32%) had no alternative explanation. Of these, 66% received appropriate empiric antimicrobial therapy, but no targeted therapy changes were made based on urine culture results. The other 34% did not receive antimicrobial therapy at all. Only 6% of all CAUTIs resulted in blood cultures positive for the same organism within 2 days. The urinary tract was not definitely established as the source of bloodstream infection. conclusions. Urine cultures obtained for evaluation of fever form the basis for identification of CAUTIs in the ICU. However, most patients with CAUTIs are eventually found to have alternative explanations for fever. CAUTI is associated with a low complication rate. Infect. Control Hosp. Epidemiol. 2 01 5 ;3 6 (1 1) :1 33 0 – 13 34
Indwelling urinary catheters are frequently used in critically ill patients. Approximately 66% of patients in intensive care have urinary catheters in place.1 Almost 50% of all ICU patients have a fever during their ICU stay.2 Presence of an indwelling urinary catheter, fever, and bacteriuria together satisfy the National Healthcare Safety Network (NHSN) surveillance definition of catheter-associated urinary tract infection (CAUTI), which is used by participating hospitals nationwide to report CAUTI to the NHSN program. CAUTI rates are available to the public and are considered an indicator of hospital quality. Institutions with high CAUTI rates may incur revenue reductions through pay-for-performance programs such as value-based purchasing and healthcareassociated conditions programs. The 2015 CDC healthcareassociated infection (HAI) progress report based on NHSN data indicates that CAUTI is the only monitored HAI that has increased during the 2010–2013 time period. This finding
has led to an increased commitment to reduction initiatives nationwide. CAUTI reduction, however, is challenging and outcomes have been inconsistent. The lack of specificity of the NHSN definition, particularly in critically ill patients, has been a major limitation. In addition, the surveillance definition does not always reflect the clinical practices of intensivists or infectious disease consultants.3 Here, we sought to delineate the epidemiology of CAUTIs to better understand the value of obtaining urine cultures during fever in the ICU setting.
methods Mayo Clinic is a 1,200-bed hospital with 158 adult intensive care beds. CAUTIs identified using the 2012 and 2013 NHSN surveillance definition form the basis for our cohort.4,5
Affiliations: 1. Division of Critical Care Medicine, Mayo Clinic, Rochester, Minnesota; 2. Division of Infectious Disease, Mayo Clinic, Rochester, Minnesota; 3. Infection Prevention and Control, Mayo Clinic, Rochester, Minnesota. Received March 30, 2015; accepted June 24, 2015; electronically published July 20, 2015 © 2015 by The Society for Healthcare Epidemiology of America. All rights reserved. 0899-823X/2015/3611-0012. DOI: 10.1017/ice.2015.172
cauti in the icu
The most commonly applied NHSN definition required an indwelling urinary catheter in place for >2 calendar days, a positive urine culture with ≤2 species of microorganisms, and at ≥1 of the clinical signs or symptoms (fever >38°C, suprapubic tenderness, or costovertebral angle pain or tenderness).4,5 Our study cohort was comprised of all patients with CAUTI attributed to ICU stay between January 1, 2012, and December 31, 2013. We performed chart reviews to abstract information on urinary catheters, indications for urine culture, symptoms, antimicrobial therapy, and patient outcomes. When fever was the primary indication for urine culture, we performed a chart review to ascertain the cause of fever. Fever evaluation varied according to the complexity of each case. It included history and physical exam, laboratory tests, blood, urine and, lower respiratory tract cultures, and in some patients, lumbar puncture or imaging studies. Patients were followed until death or discharge from the hospital. The primary outcomes were hospital mortality, hospital and ICU length of stay, and bloodstream infection as a result of CAUTI. We used standard descriptive statistical
table 1a. Baseline Demographics for 105 ICU Patients with a CAUTI Event Patient Characteristics Median age, y Age ≥65 years old Male Mean APACHE III scores ± SD Median SOFA scores [IQR] Comorbidities Diabetes mellitus Stroke/intracranial hemorrhage Chronic kidney disease End-stage liver disease Transplant recipients
n (%) 64 (range, 2–94) 52 (50) 36 (34) 71 ± 28 6 [4–9.5] 23 (22) 20 (19) 7 (7) 5 (5) 10 (10)
NOTE. ICU, intensive care unit; CAUTI, catheter-associated urinary tract infection; SD, standard deviation; APACHE Acute Physiology and Chronic Health Evaluation; SOFA, Sequential Organ Failure Assessment.
table 1b.
methods and performed analysis with JMP 10 software (SAS Institute, Cary, NC).
resul ts A total of 105 ICU CAUTIs were identified in 6 adult ICUs in 2012 and 2013, for a CAUTI rate of 2.5 per 1,000 catheter days. The observation period included 42,461 catheter days and 72,799 patient days for a device utilization ratio (DUR) of 0.58. A total of 5,243 urine cultures were performed on catheterized urine specimens in this cohort (72 urine cultures per 1,000 patient days, 194 urine cultures per 1,000 ICU admissions). Descriptive characteristics of the cohort can be found in Table 1a. CAUTI rates and DUR by ICU type are reported in Table 1b. The most common organisms identified by urine culture were yeast (50%), E. coli (18%), Enterococcus spp. (12%), and Pseudomonas spp. (6%) (Table 2). The primary indication for urine culture was fever (102 of 105 patients, 97%). In the majority of patients, a possible alternative explanation of fever was identified. Infection other than CAUTI was found in 51 of 102 patients (51%), which included pneumonia (n = 28, 55%), followed by bloodstream infection (n = 11, 22%). The diagnosis of pneumonia was made on clinical grounds that included a clinical assessment, lower respiratory tract cultures, and radiography. The diagnosis of bloodstream infection was based on positive blood cultures. In 18 of 102 patients (18%), a potential noninfectious cause was identified. Intracranial bleed was the most common potential noninfectious cause (n = 6, 33%), followed by postoperative fever (n = 4, 22%). Only 32 of the 102 patients (32%) had no alternative explanation for fever. Of these 32 patients, 21 (66%) initially received empiric antimicrobial therapy at onset of fever, but no targeted antimicrobial therapy changes were made based on the urine culture results. The other 11 patients (34%) did not receive antimicrobial therapy at all. Most of these patients (73%) had candiduria. Finally, only 6% of all ICU CAUTIs resulted in blood cultures positive with same organism within 2 days (Table 3). The median ICU length of stay for the patients with CAUTI
CAUTI rates and DUR per ICU Type in 105 ICU Patients with a CAUTI Event in 2012 and 2013
Type of ICU Coronary care unit Cardiac surgery ICU Medical ICU Surgical ICUb Mixed medical/surgical/transplant ICU Neurological ICU Total NOTE. a
1331
Admissions
CAUTI events, n (%)
Catheter days
Patient days
CAUTI ratea
DUR
2,645 4,596 5,618 6,235 3,283 4,270 26,647
3 (3) 12 (11) 26 (25) 30 (29) 13 (12) 23 (22) 105 (100)
2,392 8,670 7,573 12,571 4,676 6,579 42,461
7,956 13,207 11,859 22,005 7,356 10,416 72,799
1.25 1.38 3.43 2.39 2.78 3.50 2.47
0.30 0.66 0.64 0.57 0.64 0.63 0.58
CAUTI, catheter-associated urinary tract infection; DUR, device utilization ratio; ICU, intensive care unit. CAUTI rate is reported per 1,000 patient days. b Surgical ICU includes general, vascular, thoracic, trauma ICUs.
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november 2015, vol. 36, no. 11
was 10 days (interquartile range: 6–16 days). In-hospital all-cause mortality was 28%.
d i s c u s s io n We performed a 2-year retrospective cohort analysis of adult ICU patients who met the NHSN surveillance definition for CAUTI. The majority of patients in our ICUs had urine cultures performed as a part of the clinical evaluation for fever. A minority of patients had urine cultures sent based on other symptoms other than fever. In most patients with CAUTI, fever could most often be attributed to another source: pneumonia, bloodstream infection, or an intracranial bleed. This finding is consistent with previous studies.6–8 Fever is extremely common in critically ill patients, and its significance varies depending on clinical context. table 2.
CAUTI Pathogens
Organisms Yeast E. coli Enterococcus spp Vancomycin-resistant K. pneumoniae P. mirabilis E. cloacae P. aeruginosa Coagulase-negative Staphylococcus spp. Othera
n (N = 111)
%
56 20 13 7 3 2 4 7 2 4
50 18 12 7 3 2 4 6 2 4
NOTE. a
CAUTI, catheter-associated urinary tract infection; Streptococcus Group B, M. morganii, Acinetobacter spp., Citrobacter spp.
table 3.
Fever in the ICU is at times felt to be equivalent with infection, triggering cultures from multiple sites including blood, sputum, and urine cultures. Any unexplained fever warrants a thorough clinical evaluation that includes a complete history and physical examination. The 2009 IDSA guideline for the diagnosis of CAUTI suggested that catheterized patients be thoroughly evaluated for alternative sources, before attributing symptoms including fever to the urinary tract.9 Laboratory tests should be ordered only after a clinical evaluation indicates a reasonable pre-test probability that infection might be present.10 Because of the high frequency of asymptomatic bacteriuria, positive urine cultures often mislead, if not confuse, clinicians in management of the patient. Previous studies have reported that fever in the ICU is represented equally by infectious and noninfectious causes, with the infectious causes usually being infection of the lower respiratory tract, blood, and abdomen.11,12 Catheter-associated bacteriuria or candiduria usually represents colonization and is rarely symptomatic.13 The NHSN surveillance definition is promoted as an objective measure of performance and a marker of quality of care. Limitations of the definition are widely recognized. Hanna et al3 found that the NHSN definition of CAUTI did not co-relate with clinical practice of either non-infectious disease or infectious disease physicians. In 2009, the NHSN eliminated catheter-associated asymptomatic bacteriuria as part of the definition. As a result, a significant decrease in the incidence of CAUTI was observed, although overall it still did not change the rate of subsequent antibiotic use in patients with positive urine cultures.14 In 2013, the NHSN definition was revised again in relation to fever alone as a symptom.4 Fever is attributed to CAUTI regardless of an alternative explanation. Almost 66% of our cohort had a potential
ICU Patients with CAUTIs that Resulted in Blood Cultures Positive with the Same Organism Within 2 days
Blood Cultures
History
Interpretation
1
Enterobacter cloacae (single blood culture)
BSI with possible source of urinary tract
2
VRE (single blood culture)
3
VRE (single blood culture)
4 5
Pseudomonas aeruginosa (multiple cultures) P. aeruginosa (multiple cultures)
6
VRE (multiple cultures)
75-year-old woman with aortic valve replacement for infective endocarditis, polymicrobial urine culture (Enterobacter and Morganella spp.) 61-year-old woman with ARDS, pneumonia, on ECMO 71-year-old woman with CNS lymphoma with neurologic complications of chemotherapy 77-year-old man with subarachnoid hemorrhage, aneurysm, and sepsis 62-year-old woman with T-cell leukemia, allogeneic HSCT recipient, complicated with GvHD of skin, gut, pneumonia 57-year-old woman with non-Hodgkin’s lymphoma who underwent chemotherapy and had neutropenic fever
BSI with possible source of urinary tract BSI with possible source of urinary tract BSI with possible source of urinary tract BSI preceded positive urine cultures
Possible translocation from bowel
NOTE. ICU, intensive care unit; CAUTI, catheter-associated urinary tract infection; BSI, bloodstream infection; VRE, vancomycin-resistant enterococcus; ARDS, acute respiratory distress syndrome; ECMO, extracorporeal membrane oxygenation; CNS, central nervous system; HSCT, hematopoietic stem cell transplantation; GvHD, graft-versus-host disease.
cauti in the icu
alternative cause of fever. Even in patients with no other identified cause of fever, urine cultures were not acted upon in 34% of cases. Of these patients, 66% had received appropriate empiric antibiotics in their early febrile course, and no targeted change in antimicrobial therapy was made after the results of urine cultures. This finding suggests that urine cultures in ICU patients rarely help clinicians manage overall patient care. Yeast has been known to frequently colonize urinary catheters. Approximately 50% of isolated organisms in our cohort were yeast. The 2015 NHSN definition has eliminated reporting of candiduria.15 Although this definition has increased specificity, the window during which the nonspecific signs or symptoms including fever count toward the CAUTI definition has increased. With the high frequency of fever in ICU, the definition will cause the overestimation of the incidence of clinically significant CAUTI and is unlikely to be a good measure of hospital quality. Further studies are needed to address the non-specific relationship between fever and bacteriuria to improve the specificity of the NHSN definition in ICU patients. We identified only 6 patients (6%) in our cohort who had blood cultures positive with the same organism isolated from urine specimen within 2 days (Table 3). It was difficult to differentiate whether the bloodstream infection originated from the urinary tract, was filtered from the bloodstream into the urinary tract, or whether the bladder was an unrelated reservoir. In 2 of the patients, the urinary tract was unlikely to be the source. One patient had vancomycin-resistant Enterococcus (VRE) bacteremia in the setting of neutropenia, and the bloodstream infection was possibly related to the translocation of the enteric pathogen across the compromised colonic mucosa. The other patient had persistently positive blood cultures for P. aeruginosa prior to the positive urine culture, which suggests likely filtration of the pathogen into the genitourinary system. Our findings highlight the low number of complications associated with CAUTI in the ICU patients, which is consistent with previous studies.16 This finding brings into question the utility of surveillance for this low-frequency, low-morbidity HAI, which does not serve as a valuable patient-centered outcome. Our study has several limitations. First, it was performed in a single tertiary-care hospital with multiple ICU populations, which may not be representative of other settings. Second, due to the retrospective nature of our study, we relied on the clinical judgment of clinicians caring for the patient in investigating the cause of fever. Third, our cohort was limited to a 2-year study period. Fourth, half of our cohort had yeast as the predominant organism, and with the recent 2015 NHSN definition change that eliminates yeast, our findings are less relevant. However, the frequency of fever in ICU patients will remain high, and as long as clinicians continue culturing urine as part of the clinical evaluation of fever, CAUTI rates will remain high. Further study of the impact of the 2015 NHSN definition changes is needed. In conclusion, we have demonstrated that most ICU CAUTIs identified by the NHSN surveillance definition are not
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clinically significant. The practice of obtaining “pan cultures” in response to fever results in CAUTIs. Reducing catheter utilization is a laudable goal because the catheterized bladder serves as a reservoir for bacteria and yeast. However, CAUTIs, as currently defined by NHSN (even with the 2015 definition changes), are not clinically relevant, and efforts to reduce CAUTI may be better directed at other more serious healthcare infections. CAUTI rates are a reflection of institutional culturing practices, and the current emphasis on CAUTI as a measure of a hospitals quality may be misguided.
acknowledgments Financial support. This manuscript was developed and completed in the absence of an outside funding source. Potential conflicts of interest. At the time of the study, all authors were employed by Mayo Clinic. All authors report no conflicts of interest relevant to this article. Address correspondence to Rudy Tedja, 200 First Street SW, Marian Hall 2-115, Rochester, MN 55905 ([email protected]).
ref e ren ces 1. Dudeck MA, Horan TC, Peterson KD, et al. National Healthcare Safety Network report, data summary for 2011, device-associated module. Am J Infect Control 2013;41:286–300. 2. Laupland KB, Shahpori R, Kirkpatrick AW, Ross T, Gregson DB, Stelfox HT. Occurrence and outcome of fever in critically ill adults. Crit Care Med 2008;36:1531–1535. 3. Al-Qas Hanna F, Sambirska O, Iyer S, Szpunar S, Fakih MG. Clinician practice and the National Healthcare Safety Network definition for the diagnosis of catheter-associated urinary tract infection. Am J Infect Control 2013;41:1173–1177. 4. Catheter-associated urinary tract infection (CAUTI) event. Centers for Disease Control and Prevention website. http://www. cdc.gov/nhsn/PDFs/pscManual/validation/pscManual_july2013. pdf. Published 2013. Accessed May 16, 2015. 5. Catheter-Associated Urinary Tract Infection (CAUTI) event. Centers for Disease Control and Prevention website. http:// onthecuspstophai.org/wp-content/uploads/2012/04/CDC-CAUTIEvent-Definition-Criterion-Form.pdf. Published 2012. Accessed March 24, 2015. 6. Hartley S, Valley S, Kuhn L, et al. Inappropriate testing for urinary tract infection in hospitalized patients: an opportunity for improvement. Infect Control Hosp Epidemiol 2013;34:1204–1207. 7. Neelakanta A, Sharma S, Kesani VP, et al. Impact of changes in the NHSN Catheter-Associated Urinary Tract Infection (CAUTI) surveillance criteria on the frequency and epidemiology of CAUTI in Intensive Care Units (ICUs). Infect Control Hosp Epidemiol 2015;36:346–349. 8. Meddings J, Reichert H, McMahon LF Jr. Challenges and proposed improvements for reviewing symptoms and catheter use to identify National Healthcare Safety Network catheter-associated urinary tract infections. Am J Infect Control 2014;42:S236–S241. 9. Hooton TM, Bradley SF, Cardenas DD, et al. Diagnosis, prevention, and treatment of catheter-associated urinary tract infection in adults: 2009 international clinical practice guidelines from the Infectious Diseases Society of America. Clin Infect Dis 2010;50:625–663.
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10. O’Grady NP, Barie PS, Bartlett JG, et al. Guidelines for evaluation of new fever in critically ill adult patients: 2008 update from the American College of Critical Care Medicine and the Infectious Diseases Society of America. Crit Care Med 2008;36: 1330–1349. 11. Circiumaru B, Baldock G, Cohen J. A prospective study of fever in the intensive care unit. Intensive Care Med 1999;25:668–673. 12. Rehman T, Deboisblanc BP. Persistent fever in the ICU. Chest 2014;145:158–165. 13. Tambyah PA, Maki DG. Catheter-associated urinary tract infection is rarely symptomatic: a prospective study of 1,497 catheterized patients. Arch Intern Med 2000;160:678–682.
14. Press MJ, Metlay JP. Catheter-associated urinary tract infection: does changing the definition change quality? Infect Control Hosp Epidemiol 2013;34:313–315. 15. Urinary tract infection (catheter-associated urinary tract infection [CAUTI] and non-catheter-associated urinary tract infection [UTI] and other urinary system infection [USI]) events. Centers for Disease Control and Prevention website. http://www.cdc.gov/ nhsn/pdfs/pscManual/7pscCAUTIcurrent.pdf. Published 2015. Accessed February 15, 2015. 16. Kizilbash QF, Petersen NJ, Chen GJ, Naik AD, Trautner BW. Bacteremia and mortality with urinary catheter–associated bacteriuria. Infect Control Hosp Epidemiol 2013;34:1153–1159.
november 2015, vol. 36, no. 11
original article
Catheter-Associated Urinary Tract Infections in Intensive Care Unit Patients Rudy Tedja, DO;1 Jean Wentink, RN, MPH;3 John C O’Horo, MD;2 Rodney Thompson, MD;2,3 Priya Sampathkumar, MD2,3
objective. To delineate the epidemiology of catheter-associated urinary tract infections (CAUTIs) and to better understand the value of urine cultures for evaluation of fever in the intensive care unit (ICU) setting design. setting. patients.
Two-year retrospective review (2012–2013) A single tertiary center with 1,200 hospital beds and 158 adult ICU beds ICU patients with a CAUTI event
methods. The cohort was identified from a prospective infection prevention database. Charts were reviewed to characterize the patients. CAUTI rates and device utilization ratio (DUR) were calculated. Clinical outcomes were recorded. results. A total of 105 CAUTIs were identified using the National Health and Safety Network (NHSN) definition. Fever was the primary indication for obtaining urine culture in 102 patients (97%). Of these 105 patients, 51 (51%) had an alternative infection to explain the fever, with pneumonia (55%) being the most common followed by bloodstream infection (22%). A total of 18 patients (18%) had fever due to noninfectious cause, and 32 patients (32%) had no alternative explanation. Of these, 66% received appropriate empiric antimicrobial therapy, but no targeted therapy changes were made based on urine culture results. The other 34% did not receive antimicrobial therapy at all. Only 6% of all CAUTIs resulted in blood cultures positive for the same organism within 2 days. The urinary tract was not definitely established as the source of bloodstream infection. conclusions. Urine cultures obtained for evaluation of fever form the basis for identification of CAUTIs in the ICU. However, most patients with CAUTIs are eventually found to have alternative explanations for fever. CAUTI is associated with a low complication rate. Infect. Control Hosp. Epidemiol. 2 01 5 ;3 6 (1 1) :1 33 0 – 13 34
Indwelling urinary catheters are frequently used in critically ill patients. Approximately 66% of patients in intensive care have urinary catheters in place.1 Almost 50% of all ICU patients have a fever during their ICU stay.2 Presence of an indwelling urinary catheter, fever, and bacteriuria together satisfy the National Healthcare Safety Network (NHSN) surveillance definition of catheter-associated urinary tract infection (CAUTI), which is used by participating hospitals nationwide to report CAUTI to the NHSN program. CAUTI rates are available to the public and are considered an indicator of hospital quality. Institutions with high CAUTI rates may incur revenue reductions through pay-for-performance programs such as value-based purchasing and healthcareassociated conditions programs. The 2015 CDC healthcareassociated infection (HAI) progress report based on NHSN data indicates that CAUTI is the only monitored HAI that has increased during the 2010–2013 time period. This finding
has led to an increased commitment to reduction initiatives nationwide. CAUTI reduction, however, is challenging and outcomes have been inconsistent. The lack of specificity of the NHSN definition, particularly in critically ill patients, has been a major limitation. In addition, the surveillance definition does not always reflect the clinical practices of intensivists or infectious disease consultants.3 Here, we sought to delineate the epidemiology of CAUTIs to better understand the value of obtaining urine cultures during fever in the ICU setting.
methods Mayo Clinic is a 1,200-bed hospital with 158 adult intensive care beds. CAUTIs identified using the 2012 and 2013 NHSN surveillance definition form the basis for our cohort.4,5
Affiliations: 1. Division of Critical Care Medicine, Mayo Clinic, Rochester, Minnesota; 2. Division of Infectious Disease, Mayo Clinic, Rochester, Minnesota; 3. Infection Prevention and Control, Mayo Clinic, Rochester, Minnesota. Received March 30, 2015; accepted June 24, 2015; electronically published July 20, 2015 © 2015 by The Society for Healthcare Epidemiology of America. All rights reserved. 0899-823X/2015/3611-0012. DOI: 10.1017/ice.2015.172
cauti in the icu
The most commonly applied NHSN definition required an indwelling urinary catheter in place for >2 calendar days, a positive urine culture with ≤2 species of microorganisms, and at ≥1 of the clinical signs or symptoms (fever >38°C, suprapubic tenderness, or costovertebral angle pain or tenderness).4,5 Our study cohort was comprised of all patients with CAUTI attributed to ICU stay between January 1, 2012, and December 31, 2013. We performed chart reviews to abstract information on urinary catheters, indications for urine culture, symptoms, antimicrobial therapy, and patient outcomes. When fever was the primary indication for urine culture, we performed a chart review to ascertain the cause of fever. Fever evaluation varied according to the complexity of each case. It included history and physical exam, laboratory tests, blood, urine and, lower respiratory tract cultures, and in some patients, lumbar puncture or imaging studies. Patients were followed until death or discharge from the hospital. The primary outcomes were hospital mortality, hospital and ICU length of stay, and bloodstream infection as a result of CAUTI. We used standard descriptive statistical
table 1a. Baseline Demographics for 105 ICU Patients with a CAUTI Event Patient Characteristics Median age, y Age ≥65 years old Male Mean APACHE III scores ± SD Median SOFA scores [IQR] Comorbidities Diabetes mellitus Stroke/intracranial hemorrhage Chronic kidney disease End-stage liver disease Transplant recipients
n (%) 64 (range, 2–94) 52 (50) 36 (34) 71 ± 28 6 [4–9.5] 23 (22) 20 (19) 7 (7) 5 (5) 10 (10)
NOTE. ICU, intensive care unit; CAUTI, catheter-associated urinary tract infection; SD, standard deviation; APACHE Acute Physiology and Chronic Health Evaluation; SOFA, Sequential Organ Failure Assessment.
table 1b.
methods and performed analysis with JMP 10 software (SAS Institute, Cary, NC).
resul ts A total of 105 ICU CAUTIs were identified in 6 adult ICUs in 2012 and 2013, for a CAUTI rate of 2.5 per 1,000 catheter days. The observation period included 42,461 catheter days and 72,799 patient days for a device utilization ratio (DUR) of 0.58. A total of 5,243 urine cultures were performed on catheterized urine specimens in this cohort (72 urine cultures per 1,000 patient days, 194 urine cultures per 1,000 ICU admissions). Descriptive characteristics of the cohort can be found in Table 1a. CAUTI rates and DUR by ICU type are reported in Table 1b. The most common organisms identified by urine culture were yeast (50%), E. coli (18%), Enterococcus spp. (12%), and Pseudomonas spp. (6%) (Table 2). The primary indication for urine culture was fever (102 of 105 patients, 97%). In the majority of patients, a possible alternative explanation of fever was identified. Infection other than CAUTI was found in 51 of 102 patients (51%), which included pneumonia (n = 28, 55%), followed by bloodstream infection (n = 11, 22%). The diagnosis of pneumonia was made on clinical grounds that included a clinical assessment, lower respiratory tract cultures, and radiography. The diagnosis of bloodstream infection was based on positive blood cultures. In 18 of 102 patients (18%), a potential noninfectious cause was identified. Intracranial bleed was the most common potential noninfectious cause (n = 6, 33%), followed by postoperative fever (n = 4, 22%). Only 32 of the 102 patients (32%) had no alternative explanation for fever. Of these 32 patients, 21 (66%) initially received empiric antimicrobial therapy at onset of fever, but no targeted antimicrobial therapy changes were made based on the urine culture results. The other 11 patients (34%) did not receive antimicrobial therapy at all. Most of these patients (73%) had candiduria. Finally, only 6% of all ICU CAUTIs resulted in blood cultures positive with same organism within 2 days (Table 3). The median ICU length of stay for the patients with CAUTI
CAUTI rates and DUR per ICU Type in 105 ICU Patients with a CAUTI Event in 2012 and 2013
Type of ICU Coronary care unit Cardiac surgery ICU Medical ICU Surgical ICUb Mixed medical/surgical/transplant ICU Neurological ICU Total NOTE. a
1331
Admissions
CAUTI events, n (%)
Catheter days
Patient days
CAUTI ratea
DUR
2,645 4,596 5,618 6,235 3,283 4,270 26,647
3 (3) 12 (11) 26 (25) 30 (29) 13 (12) 23 (22) 105 (100)
2,392 8,670 7,573 12,571 4,676 6,579 42,461
7,956 13,207 11,859 22,005 7,356 10,416 72,799
1.25 1.38 3.43 2.39 2.78 3.50 2.47
0.30 0.66 0.64 0.57 0.64 0.63 0.58
CAUTI, catheter-associated urinary tract infection; DUR, device utilization ratio; ICU, intensive care unit. CAUTI rate is reported per 1,000 patient days. b Surgical ICU includes general, vascular, thoracic, trauma ICUs.
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november 2015, vol. 36, no. 11
was 10 days (interquartile range: 6–16 days). In-hospital all-cause mortality was 28%.
d i s c u s s io n We performed a 2-year retrospective cohort analysis of adult ICU patients who met the NHSN surveillance definition for CAUTI. The majority of patients in our ICUs had urine cultures performed as a part of the clinical evaluation for fever. A minority of patients had urine cultures sent based on other symptoms other than fever. In most patients with CAUTI, fever could most often be attributed to another source: pneumonia, bloodstream infection, or an intracranial bleed. This finding is consistent with previous studies.6–8 Fever is extremely common in critically ill patients, and its significance varies depending on clinical context. table 2.
CAUTI Pathogens
Organisms Yeast E. coli Enterococcus spp Vancomycin-resistant K. pneumoniae P. mirabilis E. cloacae P. aeruginosa Coagulase-negative Staphylococcus spp. Othera
n (N = 111)
%
56 20 13 7 3 2 4 7 2 4
50 18 12 7 3 2 4 6 2 4
NOTE. a
CAUTI, catheter-associated urinary tract infection; Streptococcus Group B, M. morganii, Acinetobacter spp., Citrobacter spp.
table 3.
Fever in the ICU is at times felt to be equivalent with infection, triggering cultures from multiple sites including blood, sputum, and urine cultures. Any unexplained fever warrants a thorough clinical evaluation that includes a complete history and physical examination. The 2009 IDSA guideline for the diagnosis of CAUTI suggested that catheterized patients be thoroughly evaluated for alternative sources, before attributing symptoms including fever to the urinary tract.9 Laboratory tests should be ordered only after a clinical evaluation indicates a reasonable pre-test probability that infection might be present.10 Because of the high frequency of asymptomatic bacteriuria, positive urine cultures often mislead, if not confuse, clinicians in management of the patient. Previous studies have reported that fever in the ICU is represented equally by infectious and noninfectious causes, with the infectious causes usually being infection of the lower respiratory tract, blood, and abdomen.11,12 Catheter-associated bacteriuria or candiduria usually represents colonization and is rarely symptomatic.13 The NHSN surveillance definition is promoted as an objective measure of performance and a marker of quality of care. Limitations of the definition are widely recognized. Hanna et al3 found that the NHSN definition of CAUTI did not co-relate with clinical practice of either non-infectious disease or infectious disease physicians. In 2009, the NHSN eliminated catheter-associated asymptomatic bacteriuria as part of the definition. As a result, a significant decrease in the incidence of CAUTI was observed, although overall it still did not change the rate of subsequent antibiotic use in patients with positive urine cultures.14 In 2013, the NHSN definition was revised again in relation to fever alone as a symptom.4 Fever is attributed to CAUTI regardless of an alternative explanation. Almost 66% of our cohort had a potential
ICU Patients with CAUTIs that Resulted in Blood Cultures Positive with the Same Organism Within 2 days
Blood Cultures
History
Interpretation
1
Enterobacter cloacae (single blood culture)
BSI with possible source of urinary tract
2
VRE (single blood culture)
3
VRE (single blood culture)
4 5
Pseudomonas aeruginosa (multiple cultures) P. aeruginosa (multiple cultures)
6
VRE (multiple cultures)
75-year-old woman with aortic valve replacement for infective endocarditis, polymicrobial urine culture (Enterobacter and Morganella spp.) 61-year-old woman with ARDS, pneumonia, on ECMO 71-year-old woman with CNS lymphoma with neurologic complications of chemotherapy 77-year-old man with subarachnoid hemorrhage, aneurysm, and sepsis 62-year-old woman with T-cell leukemia, allogeneic HSCT recipient, complicated with GvHD of skin, gut, pneumonia 57-year-old woman with non-Hodgkin’s lymphoma who underwent chemotherapy and had neutropenic fever
BSI with possible source of urinary tract BSI with possible source of urinary tract BSI with possible source of urinary tract BSI preceded positive urine cultures
Possible translocation from bowel
NOTE. ICU, intensive care unit; CAUTI, catheter-associated urinary tract infection; BSI, bloodstream infection; VRE, vancomycin-resistant enterococcus; ARDS, acute respiratory distress syndrome; ECMO, extracorporeal membrane oxygenation; CNS, central nervous system; HSCT, hematopoietic stem cell transplantation; GvHD, graft-versus-host disease.
cauti in the icu
alternative cause of fever. Even in patients with no other identified cause of fever, urine cultures were not acted upon in 34% of cases. Of these patients, 66% had received appropriate empiric antibiotics in their early febrile course, and no targeted change in antimicrobial therapy was made after the results of urine cultures. This finding suggests that urine cultures in ICU patients rarely help clinicians manage overall patient care. Yeast has been known to frequently colonize urinary catheters. Approximately 50% of isolated organisms in our cohort were yeast. The 2015 NHSN definition has eliminated reporting of candiduria.15 Although this definition has increased specificity, the window during which the nonspecific signs or symptoms including fever count toward the CAUTI definition has increased. With the high frequency of fever in ICU, the definition will cause the overestimation of the incidence of clinically significant CAUTI and is unlikely to be a good measure of hospital quality. Further studies are needed to address the non-specific relationship between fever and bacteriuria to improve the specificity of the NHSN definition in ICU patients. We identified only 6 patients (6%) in our cohort who had blood cultures positive with the same organism isolated from urine specimen within 2 days (Table 3). It was difficult to differentiate whether the bloodstream infection originated from the urinary tract, was filtered from the bloodstream into the urinary tract, or whether the bladder was an unrelated reservoir. In 2 of the patients, the urinary tract was unlikely to be the source. One patient had vancomycin-resistant Enterococcus (VRE) bacteremia in the setting of neutropenia, and the bloodstream infection was possibly related to the translocation of the enteric pathogen across the compromised colonic mucosa. The other patient had persistently positive blood cultures for P. aeruginosa prior to the positive urine culture, which suggests likely filtration of the pathogen into the genitourinary system. Our findings highlight the low number of complications associated with CAUTI in the ICU patients, which is consistent with previous studies.16 This finding brings into question the utility of surveillance for this low-frequency, low-morbidity HAI, which does not serve as a valuable patient-centered outcome. Our study has several limitations. First, it was performed in a single tertiary-care hospital with multiple ICU populations, which may not be representative of other settings. Second, due to the retrospective nature of our study, we relied on the clinical judgment of clinicians caring for the patient in investigating the cause of fever. Third, our cohort was limited to a 2-year study period. Fourth, half of our cohort had yeast as the predominant organism, and with the recent 2015 NHSN definition change that eliminates yeast, our findings are less relevant. However, the frequency of fever in ICU patients will remain high, and as long as clinicians continue culturing urine as part of the clinical evaluation of fever, CAUTI rates will remain high. Further study of the impact of the 2015 NHSN definition changes is needed. In conclusion, we have demonstrated that most ICU CAUTIs identified by the NHSN surveillance definition are not
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clinically significant. The practice of obtaining “pan cultures” in response to fever results in CAUTIs. Reducing catheter utilization is a laudable goal because the catheterized bladder serves as a reservoir for bacteria and yeast. However, CAUTIs, as currently defined by NHSN (even with the 2015 definition changes), are not clinically relevant, and efforts to reduce CAUTI may be better directed at other more serious healthcare infections. CAUTI rates are a reflection of institutional culturing practices, and the current emphasis on CAUTI as a measure of a hospitals quality may be misguided.
acknowledgments Financial support. This manuscript was developed and completed in the absence of an outside funding source. Potential conflicts of interest. At the time of the study, all authors were employed by Mayo Clinic. All authors report no conflicts of interest relevant to this article. Address correspondence to Rudy Tedja, 200 First Street SW, Marian Hall 2-115, Rochester, MN 55905 ([email protected]).
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