Original Article
695
Urinary Tract Infections in a Neonatal Intensive Care Unit Mark F. Weems, MD1 Daniel Wei, MD2 Rangasamy Ramanathan, MD2 Linda Vachon, MD3 Smeeta Sardesai, MD, MS Ed2
Regional One Health and Le Bonheur Children’s Hospital, University of Tennessee Health Science Center, Memphis, Tennessee 2 Division of Neonatal Medicine, Department of Pediatrics, Keck School of Medicine of USC, LAC þ USC Medical Center, University of Southern California, Los Angeles, California 3 Department of Radiology, Keck School of Medicine of USC, LAC þ USC Medical Center, University of Southern California, Los Angeles, California
Address for correspondence Mark F. Weems, MD, Division of Neonatal-Perinatal Medicine, Department of Pediatrics, Regional One Health and Le Bonheur Children’s Hospital, University of Tennessee Health Science Center; 853 Jefferson Avenue, Rout Bldg E201, Memphis, TN, 38163 (e-mail: [email protected]).
Am J Perinatol 2015;32:695–702.
Abstract
Keywords
► ultrasound ► voiding cystourethrogram ► vesicoureteral reflux ► neonate ► infant ► urinary tract infection
Objective Our aim was to describe laboratory findings and imaging results for neonatal patients diagnosed with urinary tract infection (UTI). Study Design Medical records were reviewed for infants diagnosed with UTI in a single neonatal intensive care unit (NICU) over a 13-year period. Results Of the 8,241 patients admitted to the NICU during the study period, 137 infants were diagnosed with UTI. Imaging was reviewed for 101 patients. Renal pelvis dilation was found in 34% of patients and vesicoureteral reflux was found in 21%. Renal pelvis dilation was not associated with reflux (OR: 0.53 [95% CI: 0.18–1.5]). The sensitivity of urinalysis to detect a positive culture was 76%, and the specificity was 41%. Tests of cure for bacterial infections were uniformly negative. Conclusion Renal pelvis dilation was common but not associated with reflux among NICU patients diagnosed with UTI. Diagnostic criteria in this population are not well defined, and guidelines are needed for diagnosis and management of UTIs in NICU patients.
Urinary tract infections (UTIs) occur commonly in both pediatric and neonatal populations. Approximately 5% of children aged 2 to 24 months with unexplained fever are found to have a UTI.1 Prevalence can vary from 0.1 to 1% in all neonates and 4 to 25% in preterm neonates.2,3 The American Academy of Pediatrics (AAP) first published recommendations for the diagnosis and management of UTI in 1999.4 In 2011, the AAP revised the Clinical Practice Guideline for the diagnosis and management of the initial UTI in febrile infants and children. However, infants less than two months of age were excluded from the Guideline because there is a lack of data for the diagnosis and treatment of UTI in this age group. Neonatologists are left without a standardized strategy for managing UTI in neonatal patients despite evidence that
these younger infants are at increased risk for UTI, reflux, and long-term sequelae due to ionizing radiation associated with urinary tract imaging.2,5–7 In this study, we present our retrospective data of infants diagnosed with UTI in a single neonatal intensive care unit (NICU).
received March 5, 2014 accepted after revision September 18, 2014 published online December 17, 2014
Copyright © 2015 by Thieme Medical Publishers, Inc., 333 Seventh Avenue, New York, NY 10001, USA. Tel: +1(212) 584-4662.
Methods The University of Southern California Health Science Institutional Review Board approved this retrospective review. Patients were identified using an electronic medical record database, Neonatal Information System (Medical Data Systems, Rosemont, PA) versions 3 and 5 at the Los Angeles
DOI http://dx.doi.org/ 10.1055/s-0034-1395474. ISSN 0735-1631.
Downloaded by: University of Pennsylvania Libraries. Copyrighted material.
1 Division of Neonatal-Perinatal Medicine, Department of Pediatrics,
Lorayne Barton, MD, MPH2
Urinary Tract Infections in a Neonatal Intensive Care Unit
Weems et al.
County þ University of Southern California (LAC þ USC) Medical Center NICU, a level III NICU that admits inborn neonates, patients transferred from other hospitals, and infants who are readmitted after having been discharged to home provided they are less than 52 weeks postmenstrual age (PMA). The study population was identified by a searching for “urinary tract infection” on the problem list or “voiding cystourethrogram” on the procedure list. The search was limited to patients with a date of birth within the range of January 1, 2000, to December 31, 2012. Medical records were reviewed for 196 patients identified through the search of the database. For the purposes of this study, UTI was defined as any positive urine culture that was collected by catheterization and treated with appropriate antimicrobial therapy based on reported sensitivities. The standard treatment course was 10 days. We note the definition used differs from the 2011 AAP definition in which the diagnosis requires both urinalysis results that suggest infection and the presence of at least 50,000 colony-forming units (CFUs) per milliliter of a uropathogen. Each infant’s date of birth, gestational age, birth weight, PMA at UTI diagnosis, culture and urinalysis results, collection method, renal ultrasound results, and voiding cystourethrogram (VCUG) results were collected. Infants were excluded if there was no UTI diagnosed during the NICU stay, if the urine culture was obtained by bag collection, and if the VCUG was performed for indications other than UTI. Maternal charts were reviewed for prenatal ultrasounds. The population was studied as a whole and as two subgroups: one group was diagnosed with UTI during the initial NICU admission; the second group had been diagnosed with UTI and admitted to the NICU after being previously discharged home. In conformance with the 2011 AAP Guideline, an abnormal ultrasound was defined as a dilated renal pelvis. The presence and degree of renal pelvis dilation was determined by the radiology report documented in the medical record. Ultrasounds were described with terms such as minimal fullness, mild pelviectasis, and hydronephrosis. These results were tested for associations with reflux on VCUG for all renal pelvis dilation and specifically for hydronephrosis. A single pediatric radiologist retrospectively reviewed all available renal ultrasound images for measurement of renal pelvis anterior-posterior (AP) diameter, the maximum AP measurement of the renal pelvis on the transverse view of the kidney. The radiologist was blinded to patient outcomes, but not to initial ultrasound reading. Renal pelvis AP diameters were tested for associations with reflux at each 1 mm increment between 1 and 7 mm. To determine sensitivity and specificity of urinalysis to identify a positive urine culture, samples collected at the time of UTI diagnosis were compared with urine samples collected from the same patients at time when the culture was negative if collection was during the NICU admission period, prior to 52 weeks PMA. Leukocyte esterase and nitrite were evaluated by dipstick. Leukocyte esterase was considered positive if reported as trace, small, moderate, large, or 3þ, and nitrite was reported as negative or positive. White blood cell (WBC)
count and bacteria were evaluated by microscopy of centrifuged urine. Five or more WBC per high power field and presence of bacteria on visual assessment of the sample were each considered positive. Data were coded and imported into Stata 12 (StataCorp LP, College Station, TX). Results were analyzed for statistical significance by binary logistic regression, binomial test, Wilcoxon rank-sum test, and Chi-square test, as applicable. Statistical testing of urinalysis results was repeated for colony counts of 10,000 and 50,000 CFU per milliliter.
American Journal of Perinatology
Vol. 32
No. 7/2015
Results During the study period, 146 infants were diagnosed with UTI in the NICU; nine patients were excluded because the urine sample was documented to be from a bag collection or clean catch. One hundred thirty-seven cases remained, representing 1.7% of the 8,241 patients admitted to LAC þ USC NICU during the time period. Diagnosis required a positive culture from a catheterized urine sample and treatment with appropriate antimicrobial therapy based on sensitivities. The standard length of treatment was 10 days, and the decision to treat was based on the clinical judgment of the treating physician. Urine culture colony counts ranged from 100 to >100,000. Fifteen infants (11%) had urine cultures repeated prior to starting treatment. Of these, four infants had an increase in their colony count, two infants had a decrease, and nine infants had the same colony count, a change in collection method, or a change in pathogen. The study population included inborn patients, patients transferred from other NICUs, and patients admitted from home prior to 52 weeks PMA. Of the 72 patients admitted from home, 31 (43%) presented with fever of at least 38°C. None of the 65 patients diagnosed with nosocomial UTI was found to have a fever; all patients in this group received urine testing with late-onset sepsis screening. Voiding cystourethrogram results were available for 101 infants. Demographic data are presented in ►Tables 1 – 4, and pathogens are listed in ►Table 5. Thirty-four (34%) infants were found to have renal pelvis dilation on ultrasound, 13 (31%) from the nosocomial group and 21 (36%) from the group diagnosed with UTI after first discharge. Thirteen (13%) were diagnosed with hydronephrosis after excluding clinically insignificant findings such as “minimal fullness” and “pelviectasis.” Twenty-one (21%) infants were found to have reflux on VCUG as detailed in ►Table 4, 11 (26%) from the nosocomial group and 10 (17%) from the after first discharge group. Neither renal pelvis dilation nor hydronephrosis were associated with reflux on VCUG in the total population (OR: 0.53 [95% CI: 0.18–1.5] and OR: 0.3 [95% CI: 0.04–1.8], respectively). Ten preterm infants were diagnosed with candidal UTI. This subpopulation had a median PMA at birth of 26 weeks and median PMA at diagnosis of 31 weeks. Sub-analysis of the 91 patients diagnosed with bacterial UTI, we found that 29 (32%) had renal pelvis dilation and 21 (23%) had reflux. We found no association between renal ultrasound abnormalities and reflux (OR: 0.59 [95% CI: 0.2–1.7]) in the subpopulation with bacterial UTI. Subanalysis of the 22 cases that met the
Downloaded by: University of Pennsylvania Libraries. Copyrighted material.
696
Urinary Tract Infections in a Neonatal Intensive Care Unit
Weems et al.
697
Table 1 Infants diagnosed with UTI Characteristic
Nosocomial UTI (n ¼ 65)
Acquired after first discharge (n ¼ 72)
Total (n ¼ 137)
Birth weight, median (IQR), g
868 (650–1,245)a
3,148 (2,731–3,633)a
2,245 (825–3,317)a
PMA at birth, median (IQR), wk
27 (25–29)
38 (36–40)
35 (27–38)
Premature infants (
695
Urinary Tract Infections in a Neonatal Intensive Care Unit Mark F. Weems, MD1 Daniel Wei, MD2 Rangasamy Ramanathan, MD2 Linda Vachon, MD3 Smeeta Sardesai, MD, MS Ed2
Regional One Health and Le Bonheur Children’s Hospital, University of Tennessee Health Science Center, Memphis, Tennessee 2 Division of Neonatal Medicine, Department of Pediatrics, Keck School of Medicine of USC, LAC þ USC Medical Center, University of Southern California, Los Angeles, California 3 Department of Radiology, Keck School of Medicine of USC, LAC þ USC Medical Center, University of Southern California, Los Angeles, California
Address for correspondence Mark F. Weems, MD, Division of Neonatal-Perinatal Medicine, Department of Pediatrics, Regional One Health and Le Bonheur Children’s Hospital, University of Tennessee Health Science Center; 853 Jefferson Avenue, Rout Bldg E201, Memphis, TN, 38163 (e-mail: [email protected]).
Am J Perinatol 2015;32:695–702.
Abstract
Keywords
► ultrasound ► voiding cystourethrogram ► vesicoureteral reflux ► neonate ► infant ► urinary tract infection
Objective Our aim was to describe laboratory findings and imaging results for neonatal patients diagnosed with urinary tract infection (UTI). Study Design Medical records were reviewed for infants diagnosed with UTI in a single neonatal intensive care unit (NICU) over a 13-year period. Results Of the 8,241 patients admitted to the NICU during the study period, 137 infants were diagnosed with UTI. Imaging was reviewed for 101 patients. Renal pelvis dilation was found in 34% of patients and vesicoureteral reflux was found in 21%. Renal pelvis dilation was not associated with reflux (OR: 0.53 [95% CI: 0.18–1.5]). The sensitivity of urinalysis to detect a positive culture was 76%, and the specificity was 41%. Tests of cure for bacterial infections were uniformly negative. Conclusion Renal pelvis dilation was common but not associated with reflux among NICU patients diagnosed with UTI. Diagnostic criteria in this population are not well defined, and guidelines are needed for diagnosis and management of UTIs in NICU patients.
Urinary tract infections (UTIs) occur commonly in both pediatric and neonatal populations. Approximately 5% of children aged 2 to 24 months with unexplained fever are found to have a UTI.1 Prevalence can vary from 0.1 to 1% in all neonates and 4 to 25% in preterm neonates.2,3 The American Academy of Pediatrics (AAP) first published recommendations for the diagnosis and management of UTI in 1999.4 In 2011, the AAP revised the Clinical Practice Guideline for the diagnosis and management of the initial UTI in febrile infants and children. However, infants less than two months of age were excluded from the Guideline because there is a lack of data for the diagnosis and treatment of UTI in this age group. Neonatologists are left without a standardized strategy for managing UTI in neonatal patients despite evidence that
these younger infants are at increased risk for UTI, reflux, and long-term sequelae due to ionizing radiation associated with urinary tract imaging.2,5–7 In this study, we present our retrospective data of infants diagnosed with UTI in a single neonatal intensive care unit (NICU).
received March 5, 2014 accepted after revision September 18, 2014 published online December 17, 2014
Copyright © 2015 by Thieme Medical Publishers, Inc., 333 Seventh Avenue, New York, NY 10001, USA. Tel: +1(212) 584-4662.
Methods The University of Southern California Health Science Institutional Review Board approved this retrospective review. Patients were identified using an electronic medical record database, Neonatal Information System (Medical Data Systems, Rosemont, PA) versions 3 and 5 at the Los Angeles
DOI http://dx.doi.org/ 10.1055/s-0034-1395474. ISSN 0735-1631.
Downloaded by: University of Pennsylvania Libraries. Copyrighted material.
1 Division of Neonatal-Perinatal Medicine, Department of Pediatrics,
Lorayne Barton, MD, MPH2
Urinary Tract Infections in a Neonatal Intensive Care Unit
Weems et al.
County þ University of Southern California (LAC þ USC) Medical Center NICU, a level III NICU that admits inborn neonates, patients transferred from other hospitals, and infants who are readmitted after having been discharged to home provided they are less than 52 weeks postmenstrual age (PMA). The study population was identified by a searching for “urinary tract infection” on the problem list or “voiding cystourethrogram” on the procedure list. The search was limited to patients with a date of birth within the range of January 1, 2000, to December 31, 2012. Medical records were reviewed for 196 patients identified through the search of the database. For the purposes of this study, UTI was defined as any positive urine culture that was collected by catheterization and treated with appropriate antimicrobial therapy based on reported sensitivities. The standard treatment course was 10 days. We note the definition used differs from the 2011 AAP definition in which the diagnosis requires both urinalysis results that suggest infection and the presence of at least 50,000 colony-forming units (CFUs) per milliliter of a uropathogen. Each infant’s date of birth, gestational age, birth weight, PMA at UTI diagnosis, culture and urinalysis results, collection method, renal ultrasound results, and voiding cystourethrogram (VCUG) results were collected. Infants were excluded if there was no UTI diagnosed during the NICU stay, if the urine culture was obtained by bag collection, and if the VCUG was performed for indications other than UTI. Maternal charts were reviewed for prenatal ultrasounds. The population was studied as a whole and as two subgroups: one group was diagnosed with UTI during the initial NICU admission; the second group had been diagnosed with UTI and admitted to the NICU after being previously discharged home. In conformance with the 2011 AAP Guideline, an abnormal ultrasound was defined as a dilated renal pelvis. The presence and degree of renal pelvis dilation was determined by the radiology report documented in the medical record. Ultrasounds were described with terms such as minimal fullness, mild pelviectasis, and hydronephrosis. These results were tested for associations with reflux on VCUG for all renal pelvis dilation and specifically for hydronephrosis. A single pediatric radiologist retrospectively reviewed all available renal ultrasound images for measurement of renal pelvis anterior-posterior (AP) diameter, the maximum AP measurement of the renal pelvis on the transverse view of the kidney. The radiologist was blinded to patient outcomes, but not to initial ultrasound reading. Renal pelvis AP diameters were tested for associations with reflux at each 1 mm increment between 1 and 7 mm. To determine sensitivity and specificity of urinalysis to identify a positive urine culture, samples collected at the time of UTI diagnosis were compared with urine samples collected from the same patients at time when the culture was negative if collection was during the NICU admission period, prior to 52 weeks PMA. Leukocyte esterase and nitrite were evaluated by dipstick. Leukocyte esterase was considered positive if reported as trace, small, moderate, large, or 3þ, and nitrite was reported as negative or positive. White blood cell (WBC)
count and bacteria were evaluated by microscopy of centrifuged urine. Five or more WBC per high power field and presence of bacteria on visual assessment of the sample were each considered positive. Data were coded and imported into Stata 12 (StataCorp LP, College Station, TX). Results were analyzed for statistical significance by binary logistic regression, binomial test, Wilcoxon rank-sum test, and Chi-square test, as applicable. Statistical testing of urinalysis results was repeated for colony counts of 10,000 and 50,000 CFU per milliliter.
American Journal of Perinatology
Vol. 32
No. 7/2015
Results During the study period, 146 infants were diagnosed with UTI in the NICU; nine patients were excluded because the urine sample was documented to be from a bag collection or clean catch. One hundred thirty-seven cases remained, representing 1.7% of the 8,241 patients admitted to LAC þ USC NICU during the time period. Diagnosis required a positive culture from a catheterized urine sample and treatment with appropriate antimicrobial therapy based on sensitivities. The standard length of treatment was 10 days, and the decision to treat was based on the clinical judgment of the treating physician. Urine culture colony counts ranged from 100 to >100,000. Fifteen infants (11%) had urine cultures repeated prior to starting treatment. Of these, four infants had an increase in their colony count, two infants had a decrease, and nine infants had the same colony count, a change in collection method, or a change in pathogen. The study population included inborn patients, patients transferred from other NICUs, and patients admitted from home prior to 52 weeks PMA. Of the 72 patients admitted from home, 31 (43%) presented with fever of at least 38°C. None of the 65 patients diagnosed with nosocomial UTI was found to have a fever; all patients in this group received urine testing with late-onset sepsis screening. Voiding cystourethrogram results were available for 101 infants. Demographic data are presented in ►Tables 1 – 4, and pathogens are listed in ►Table 5. Thirty-four (34%) infants were found to have renal pelvis dilation on ultrasound, 13 (31%) from the nosocomial group and 21 (36%) from the group diagnosed with UTI after first discharge. Thirteen (13%) were diagnosed with hydronephrosis after excluding clinically insignificant findings such as “minimal fullness” and “pelviectasis.” Twenty-one (21%) infants were found to have reflux on VCUG as detailed in ►Table 4, 11 (26%) from the nosocomial group and 10 (17%) from the after first discharge group. Neither renal pelvis dilation nor hydronephrosis were associated with reflux on VCUG in the total population (OR: 0.53 [95% CI: 0.18–1.5] and OR: 0.3 [95% CI: 0.04–1.8], respectively). Ten preterm infants were diagnosed with candidal UTI. This subpopulation had a median PMA at birth of 26 weeks and median PMA at diagnosis of 31 weeks. Sub-analysis of the 91 patients diagnosed with bacterial UTI, we found that 29 (32%) had renal pelvis dilation and 21 (23%) had reflux. We found no association between renal ultrasound abnormalities and reflux (OR: 0.59 [95% CI: 0.2–1.7]) in the subpopulation with bacterial UTI. Subanalysis of the 22 cases that met the
Downloaded by: University of Pennsylvania Libraries. Copyrighted material.
696
Urinary Tract Infections in a Neonatal Intensive Care Unit
Weems et al.
697
Table 1 Infants diagnosed with UTI Characteristic
Nosocomial UTI (n ¼ 65)
Acquired after first discharge (n ¼ 72)
Total (n ¼ 137)
Birth weight, median (IQR), g
868 (650–1,245)a
3,148 (2,731–3,633)a
2,245 (825–3,317)a
PMA at birth, median (IQR), wk
27 (25–29)
38 (36–40)
35 (27–38)
Premature infants (
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