Kerri A Thom

University of Maryland, Baltimore, Baltimore, Maryland, United States

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Publications (64)172.01 Total impact

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    ABSTRACT: OBJECTIVE To determine the prevalence of Pseudomonas aeruginosa colonization on intensive care unit (ICU) admission, risk factors for P. aeruginosa colonization, and the incidence of subsequent clinical culture with P. aeruginosa among those colonized and not colonized. METHODS We conducted a cohort study of patients admitted to a medical or surgical intensive care unit of a tertiary care hospital. Patients had admission perirectal surveillance cultures performed. Risk factors analyzed included comorbidities at admission, age, sex, antibiotics received during current hospitalization before ICU admission, and type of ICU. RESULTS Of 1,840 patients, 213 (11.6%) were colonized with P. aeruginosa on ICU admission. Significant risk factors in the multivariable analysis for colonization were age (odds ratio, 1.02 [95% CI, 1.01-1.03]), anemia (1.90 [1.05-3.42]), and neurologic disorder (1.80 [1.27-2.54]). Of the 213 patients colonized with P. aeruginosa on admission, 41 (19.2%) had a subsequent clinical culture positive for P. aeruginosa on ICU admission and 60 (28.2%) had a subsequent clinical culture positive for P. aeruginosa in the current hospitalization (ICU period and post-ICU period). Of these 60 patients, 49 (81.7%) had clinical infections. Of the 1,627 patients not colonized on admission, only 68 (4.2%) had a subsequent clinical culture positive for P. aeruginosa in the current hospitalization. Patients colonized with P. aeruginosa were more likely to have a subsequent positive clinical culture than patients not colonized (incidence rate ratio, 6.74 [95% CI, 4.91-9.25]). CONCLUSIONS Prediction rules or rapid diagnostic testing will help clinicians more appropriately choose empirical antibiotic therapy for subsequent infections. Infect. Control Hosp. Epidemiol. 2016;1-5.
    No preview · Article · Feb 2016 · Infection Control and Hospital Epidemiology
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    ABSTRACT: OBJECTIVE To assess antimicrobial utilization before and after a change in urine culture ordering practice in adult intensive care units (ICUs) whereby urine cultures were only performed when pyuria was detected. DESIGN Quasi-experimental study SETTING A 700-bed academic medical center PATIENTS Patients admitted to any adult ICU METHODS Aggregate data for all adult ICUs were obtained for population-level antimicrobial use (days of therapy [DOT]), urine cultures performed, and bacteriuria, all measured per 1,000 patient days before the intervention (January-December 2012) and after the intervention (January-December 2013). These data were compared using interrupted time series negative binomial regression. Randomly selected patient charts from the population of adult ICU patients with orders for urine culture in the presence of indwelling or recently removed urinary catheters were reviewed for demographic, clinical, and antimicrobial use characteristics, and pre- and post-intervention data were compared. RESULTS Statistically significant reductions were observed in aggregate monthly rates of urine cultures performed and bacteriuria detected but not in DOT. At the patient level, compared with the pre-intervention group (n=250), in the post-intervention group (n=250), fewer patients started a new antimicrobial therapy based on urine culture results (23% vs 41%, P=.002), but no difference in the mean total DOT was observed. CONCLUSION A change in urine-culture ordering practice was associated with a decrease in the percentage of patients starting a new antimicrobial therapy based on the index urine-culture order but not in total duration of antimicrobial use in adult ICUs. Other drivers of antimicrobial use in ICU patients need to be evaluated by antimicrobial stewardship teams. Infect. Control Hosp. Epidemiol. 2016;1-7.
    No preview · Article · Jan 2016 · Infection Control and Hospital Epidemiology
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    ABSTRACT: BACKGROUND Central-line-associated bloodstream infection (CLABSI) rate is an important quality measure, but it suffers from subjectivity and interrater variability, and decreasing national CLABSI rates may compromise its power to discriminate between hospitals. This study evaluates hospital-onset bacteremia (HOB, ie, any positive blood culture obtained 48 hours post admission) as a healthcare-associated infection-related outcome measure by assessing the association between HOB and CLABSI rates and comparing the power of each to discriminate quality among intensive care units (ICUs). METHODS In this multicenter study, ICUs provided monthly CLABSI and HOB rates for 2012 and 2013. A Poisson regression model was used to assess the association between these 2 rates. We compared the power of each measure to discriminate between ICUs using standardized infection ratios (SIRs) with 95% confidence intervals (CIs). A measure was defined as having greater power to discriminate if more of the SIRs (with surrounding CIs) were different from 1. RESULTS In 80 ICUs from 16 hospitals in the United States and Canada, a total of 663 CLABSIs, 475,420 central line days, 11,280 HOBs, and 966,757 patient days were reported. An absolute change in HOB of 1 per 1,000 patient days was associated with a 2.5% change in CLABSI rate (P<.001). Among the 80 ICUs, 20 (25%) had a CLABSI SIR and 60 (75%) had an HOB SIR that was different from 1 (P<.001). CONCLUSION Change in HOB rate is strongly associated with change in CLABSI rate and has greater power to discriminate between ICU performances. Consideration should be given to using HOB to replace CLABSI as an outcome measure in infection prevention quality assessments. Infect. Control Hosp. Epidemiol. 2015;00(0):1-6.
    No preview · Article · Oct 2015 · Infection Control and Hospital Epidemiology
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    ABSTRACT: A prospective, single center, open-label study was conducted to determine if the standard practice for surgical prophylaxis, which includes standardized dosing of cefazolin, at the University of Maryland Medical Center (UMMC) is adequate for patients placed on bypass during cardiac surgery. All patients were given the same standard dosing regimen regardless of weight: two grams of cefazolin administered within 1 h of incision, an additional one gram injected into the bypass circuit at the onset of bypass, and two grams every 3 h after the initial dose. Cefazolin serum concentrations were collected immediately after incision, after the start of bypass, each hour of bypass, at the end of bypass and at sternal closure. Ten patients were consented and completed the study with an average age of 62 y, average weight of 84.7 kg and average cardiopulmonary bypass time of 116 min. The free serum concentrations of cefazolin stayed above the pre-defined inhibitory threshold of 16 mcg/mL throughout the procedure for 100% of participants. The mean total serum concentration in the blood throughout surgery was 160 mcg/mL. No patients were found to have surgical site infections using standard criteria and no adverse events were observed. For patients undergoing cardiac surgery with cardiopulmonary bypass, the UMMC dosing regimen surpassed targeted cefazolin concentrations during the entire surgical procedure for all patients regardless of weight or time on bypass.
    No preview · Article · Aug 2015 · Surgical Infections
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    ABSTRACT: Centers for Disease Control and Prevention (CDC) risk adjustment methods for central-line-associated bloodstream infections (CLABSI) only adjust for type of intensive care unit (ICU). This cohort study explored risk factors for CLABSI using 2 comorbidity classification schemes, the Charlson Comorbidity Index (CCI) and the Chronic Disease Score (CDS). Our study supports the need for additional research into risk factors for CLABSI, including electronically available comorbid conditions. Infect Control Hosp Epidemiol 2014;00(0): 1-3.
    No preview · Article · Apr 2015 · Infection Control and Hospital Epidemiology
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    ABSTRACT: OBJECTIVE To identify factors associated with the development of surgical site infection (SSI) among adult patients undergoing renal transplantation DESIGN A retrospective cohort study SETTING An urban tertiary care center in Baltimore, Maryland, with a well-established renal transplantation program that performs ~200-250renal transplant procedures annually RESULTS At total of 441 adult patients underwent renal transplantation between January 1, 2010, and December 31, 2011. Of these 441patients, 66 (15%) developed an SSI; of these 66, 31 (47%) were superficial incisional infections and 35 (53%) were deep-incisional or organ-space infections. The average body mass index (BMI) among this patient cohort was 29.7; 84 (42%) were obese (BMI >30). Patients who developed an SSI had a greater mean BMI (31.7 vs 29.4; P=.004) and were more likely to have a history of peripheral vascular disease, rheumatologic disease, and narcotic abuse. History of cerebral vascular disease was protective. Multivariate analysis showed BMI (odds ratio [OR] 1.06; 95% confidence interval [CI], 1.02-1.11) and past history of narcotic use/abuse (OR, 4.86; 95% CI, 1.24-19.12) to be significantly associated with development of SSI after controlling for National Healthcare Surveillance Network (NHSN) score and presence of cerebrovascular, peripheral vascular, and rheumatologic disease. CONCLUSIONS We identified higher BMI as a risk factor for the development of SSI following renal transplantation. Notably, neither aggregate comorbidity scores nor NHSN risk index were associated with SSI in this population. Additional risk adjustment measures and research in this area are needed to compare SSIs across transplant centers. Infect Control Hosp Epidemiol 2015;00(0): 1-7.
    No preview · Article · Apr 2015 · Infection Control and Hospital Epidemiology
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    ABSTRACT: Healthcare worker attire may become contaminated with pathogenic organisms during a normal shift. We performed a randomized crossover study to assess whether treatment with an antimicrobial coating would decrease bacterial contamination on scrubs. Thirty percent of all scrubs were contaminated; there was no difference in the rate of contamination between the intervention and control groups.
    No preview · Article · Nov 2014 · Infection Control and Hospital Epidemiology
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    ABSTRACT: In the management of multidrug-resistant infections in critically ill patients with multiorgan dysfunction, consideration must be given to the pharmacokinetics and pharmacodynamics of an antimicrobial agent to optimize dosing. We describe a 25-year-old woman who was undergoing thrice-weekly hemodialysis and developed multidrug-resistant Pseudomonas aeruginosa bacteremia secondary to infected left and right ventricular assist devices. After multiple courses of antibiotics, her blood cultures revealed that the infecting organism was becoming progressively more resistant to antibiotic options. Cefepime 2 g administered over 3 hours/day (in combination with colistimethate) provided adequate drug levels for multidrug-resistant, cefepime-intermediate P. aeruginosa bacteremia in this patient. We present the clinical case of this patient, followed by a discussion of possible therapeutic approaches to be considered, including illustration of the principles of using extended-infusion antimicrobial regimens, and present the patient's resulting clinical course.
    No preview · Article · Nov 2014 · Pharmacotherapy
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    ABSTRACT: Background: Current risk adjustment for central line-associated bloodstream infections (CLABSI) follows National Healthcare Safety Network (NHSN) Centers for Disease Control and Prevention (CDC) guidelines, which only adjust for ICU type. With increasing public reporting policies at the state and national level, improved risk adjustment methods are needed. Our aim was to investigate whether comorbid conditions from ICD9 components of the Charlson Comorbidity Index (CCI) and the medication-components of the Chronic Disease Score (CDS) provide information useful for further adjustment. Methods: We studied a University of Maryland Medical Center cohort of adult ICU patients admitted from July 2010 to December 2012. Data, including comorbid conditions, were from electronic medical records. CLABSIs were defined by infection preventionists. Eligible patients had a central line for at least 48 hours and no prior CLABSI during the study period. Two separate logistic regression models were constructed, one using CDS and the other using CCI components. Both models also included the number of line days. Results: 4011 subjects with 4950 central lines were included, with a total of 32577 line days at risk and 76 CLABSIs (CLABSI rate: 2.33 per 1000 line day). The mean ICU length of stay for those with a CLABSI was 30.1 days and 14.7 days for those without a CLABSI (p<0.0001). The mean days with a central line for those with a CLABSI was 10 days and 5.8 days for those without a CLABSI (p<0.01); line days was predictive of CLABSI in both models. In the CDS model, medication use associated with hypercholesterolemia and hypertenstion (calcium channel blockers) was protective, while hypertension (beta blockers) and kidney disease were associated with CLABSI (Fig 1). In the CCI model, myocardial infarction and kidney disease were associated with CLABSI (Fig 2). Conclusion: We demonstrate several risk factors for the development of CLABSI, including duration of central line and several components of the CDS and CCI such the use of lipid-lowering agents. These factors are commonly measured and often available in electronic medical records. Further study is warranted to determine if these and other risk factors will improve risk adjustment methods used by the NHSN/CDC.
    No preview · Conference Paper · Oct 2014
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    ABSTRACT: Using a validated air sampling method we found Acinetobacter baumannii in the air surrounding only 1 of 12 patients known to be colonized or infected with A. baumannii . Patients’ closed-circuit ventilator status, frequent air exchanges in patient rooms, and short sampling time may have contributed to this low burden. Infect Control Hosp Epidemiol 2015;36(7):830–832
    No preview · Conference Paper · Oct 2014
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    ABSTRACT: Objective: Hand hygiene and environmental cleaning are essential infection prevention strategies, but the relative impact of each is unknown. This information is important in assessing resource allocation. Methods: We developed an agent-based model of patient-to-patient transmission-via the hands of transiently colonized healthcare workers and incompletely terminally cleaned rooms-in a 20-patient intensive care unit. Nurses and physicians were modeled and had distinct hand hygiene compliance levels on entry and exit to patient rooms. We simulated the transmission of Acinetobacter baumannii, methicillin-resistant Staphylococcus aureus, and vancomycin-resistant enterococci for 1 year using data from the literature and observed data to inform model input parameters. Results: We simulated 175 parameter-based scenarios and compared the effects of hand hygiene and environmental cleaning on rates of multidrug-resistant organism acquisition. For all organisms, increases in hand hygiene compliance outperformed equal increases in thoroughness of terminal cleaning. From baseline, a 2∶1 improvement in terminal cleaning compared with hand hygiene was required to match an equal reduction in acquisition rates (eg, a 20% improvement in terminal cleaning was required to match the reduction in acquisition due to a 10% improvement in hand hygiene compliance). Conclusions: Hand hygiene should remain a priority for infection control programs, but environmental cleaning can have significant benefit for hospitals or individual hospital units that have either high hand hygiene compliance levels or low terminal cleaning thoroughness.
    No preview · Article · Sep 2014 · Infection Control and Hospital Epidemiology
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    ABSTRACT: We performed a real-world, controlled intervention to investigate use of an antimicrobial surface polymer, MSDS Poly, on environmental contamination. Pathogenic bacteria were identified in 18 (90%) of 20 observations in treated rooms and 19 (83%) of 23 observations in untreated rooms (P = .67). MSDS Poly had no significant effect on environmental contamination.
    No preview · Article · Aug 2014 · Infection Control and Hospital Epidemiology

  • No preview · Article · Apr 2014 · Infection Control and Hospital Epidemiology
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    ABSTRACT: We examined contamination of healthcare worker (HCW) gown and gloves after caring for patients with Klebsiella pneumoniae carbapenemase (KPC)-producing and non-KPC-producing Klebsiella as a proxy for horizontal transmission. The rate of contamination with Klebsiella species is similar to that of contamination with methicillin- resistant Staphylococcus aureus and vancomycin-resistant enterococcus, with 31 (14%) of 220 of HCW-patient interactions resulting in contamination of gloves and gowns. © 2014 by The Society for Healthcare Epidemiology of America. All rights reserved.
    No preview · Article · Apr 2014 · Infection Control and Hospital Epidemiology
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    ABSTRACT: We hypothesized that prior colonization with antibiotic-resistant Gram-negative bacteria is associated with increased risk of subsequent antibiotic-resistant Gram-negative bacteremia among cancer patients. We performed a matched case-control study. Cases were cancer patients with a blood culture positive for antibiotic-resistant Gram-negative bacteria. Controls were cancer patients with a blood culture not positive for antibiotic-resistant Gram-negative bacteria. Prior colonization was defined as any antibiotic-resistant Gram-negative bacteria in surveillance or non-sterile-site cultures obtained 2-365 days before the bacteremia. Thirty-two (37%) of 86 cases and 27 (8%) of 323 matched controls were previously colonized by any antibiotic-resistant Gram-negative bacteria. Prior colonization was strongly associated with antibiotic-resistant Gram-negative bacteremia (odds ratio [OR] 7.2, 95% confidence interval [CI] 3.5-14.7) after controlling for recent treatment with piperacillin-tazobactam (OR 2.5, 95% CI 1.3-4.8). In these patients with suspected bacteremia, prior cultures may predict increased risk of antibiotic-resistant Gram-negative bacteremia.
    No preview · Article · Jan 2014 · Diagnostic microbiology and infectious disease
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    ABSTRACT: Hand hygiene (HH) is a critical part of infection prevention in health care settings. Hospitals around the world continuously struggle to improve health care personnel (HCP) HH compliance. The current gold standard for monitoring compliance is direct observation; however, this method is time-consuming and costly. One emerging area of interest involves automated systems for monitoring HH behavior such as radiofrequency identification (RFID) tracking systems. To assess the accuracy of a commercially available RFID system in detecting HCP HH behavior, we compared direct observation with data collected by the RFID system in a simulated validation setting and to a real-life clinical setting over 2 hospitals. A total of 1,554 HH events was observed. Accuracy for identifying HH events was high in the simulated validation setting (88.5%) but relatively low in the real-life clinical setting (52.4%). This difference was significant (P < .01). Accuracy for detecting HCP movement into and out of patient rooms was also high in the simulated setting but not in the real-life clinical setting (100% on entry and exit in simulated setting vs 54.3% entry and 49.5% exit in real-life clinical setting, P < .01). In this validation study of an RFID system, almost half of the HH events were missed. More research is necessary to further develop these systems and improve accuracy prior to widespread adoption.
    No preview · Article · Dec 2013 · American journal of infection control
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    ABSTRACT: Central line (CL)-associated bloodstream infections (CLABSI) are an important cause of patient morbidity and mortality. Novel strategies to prevent CLABSI are needed. We described a quasiexperimental study to examine the effect of the presence of a unit-based quality nurse (UQN) dedicated to perform patient safety and infection control activities with a focus on CLABSI prevention in a surgical intensive care unit (SICU). From July 2008 to March 2012, there were 3,257 SICU admissions; CL utilization ratio was 0.74 (18,193 CL-days/24,576 patient-days). The UQN program began in July 2010; the nurse was present for 30% (193/518) of the days of the intervention period of July 2010 to March 2012. The average CLABSI rate was 5.0 per 1,000 CL-days before the intervention and 1.5 after the intervention and decreased by 5.1% (P = .005) for each additional 1% of days of the month that the UQN was present, even after adjusting for CLABSI rates in other adult intensive care units, time, severity of illness, and Comprehensive Unit-based Safety Program participation (5.1%, P = .004). Approximately 11.4 CLABSIs were prevented. The presence of a UQN dedicated to perform infection control activities may be an effective strategy for CLABSI reduction.
    No preview · Article · Dec 2013 · American journal of infection control
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    ABSTRACT: Background: Surgical site infections (SSI) are associated with significant morbidity, mortality and healthcare cost. Few studies have examined risk factors for development of SSI among renal transplant recipients. Methods: We performed a retrospective cohort study of adult renal transplant recipients at the University of Maryland Medical Center from January 2010 to December 2011 to identify risk factors for SSI. The primary outcome (SSI) was identified by reviewing patient medical records using defined criteria by the National Healthcare Safety Network (NHSN). Additional data (demographic and risk factors) were collected by chart review and an electronic data repository. The Chi-square and t-test were used to compare categorical and continuous variables respectively. Risk factors for SSI were identified by multiple logistic regression. Results: 441 patients underwent renal transplantation during the study period. The mean age was 53 years; 58% (256/441) were men; 47%(207/441) were African American and 48% (210/441) were white. 71% (315/441) of organs transplanted were cadaveric. 15% (66/441) of patients developed SSI; 47% (31/66) “superficial” and 53% (35/66) “deep”. 50% (220/441) were re-admitted within 30 days of transplantation; 94% (62/66) of cases and 42% (158/375) of controls (p<0.01). The table below outlines results of bi-variate analyses that were included in multivariate analysis. In the multivariate analysis only BMI was associated with the development of SSI (OR 1.07, 95% CI 1.02-1.11) Study Variables* Entire Cohort (N=441) Cases (N=66) Controls (N=375) p-value BMI 29.7 (5.9) 31.7 (5.7) 29.4 (5.9) <0.01 Surgery duration (hr) 3.2 (1.1) 3.2 (1.0) 3.3 (1.2) 0.58 NHSN Score 2.1 (0.5) 2.1 (0.5) 2.1 (0.5) 0.95 Charlson Components Cerebrovascular 20 (4.5) 0 20 (58) 0.06 Peripheral vascular 29 (6.6) 8 (12) 21 (5.6) 0.05 Rheumatologic 20 (4.5) 6 (9) 14 (3.7) 0.05 *Continuous variables (BMI, Duration) reported as mean (SD); other variables are categorical & reported as number (%) Conclusion: Obesity was strongly associated with development of SSI among renal transplant recipients. NHSN Score was not associated with development of SSI. More research is needed to identify additional measures to be used in case-mix adjustment when comparing SSI rates between facilities.
    No preview · Conference Paper · Oct 2013
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    ABSTRACT: The validity of the central line-associated bloodstream infection (CLABSI) measure is compromised by subjectivity. We observed significant decreases in both CLABSIs and total hospital-acquired bloodstream infections (BSIs) following a CLABSI prevention intervention in adult intensive care units. Total hospital-acquired BSIs could be explored as an adjunct, objective CLABSI measure.
    No preview · Article · Sep 2013 · Infection Control and Hospital Epidemiology
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    ABSTRACT: Hand hygiene (HH) is recognized as a basic effective measure in prevention of nosocomial infections. However, the importance of HH before donning nonsterile gloves is unknown, and few published studies address this issue. Despite the lack of evidence, the World Health Organization and other leading bodies recommend this practice. The aim of this study was to assess the utility of HH before donning nonsterile gloves prior to patient contact. A prospective, randomized, controlled trial of health care workers entering Contact Isolation rooms in intensive care units was performed. Baseline finger and palm prints were made from dominant hands onto agar plates. Health care workers were then randomized to directly don nonsterile gloves or perform HH and then don nonsterile gloves. Postgloving finger and palm prints were then made from the gloved hands. Plates were incubated and colony-forming units (CFU) of bacteria were counted. Total bacterial colony counts of gloved hands did not differ between the 2 groups (6.9 vs 8.1 CFU, respectively, P = .52). Staphylococcus aureus was identified from gloves (once in "hand hygiene prior to gloving" group, twice in "direct gloving" group). All other organisms were expected commensal flora. HH before donning nonsterile gloves does not decrease already low bacterial counts on gloves. The utility of HH before donning nonsterile gloves may be unnecessary.
    No preview · Article · Jul 2013 · American journal of infection control

Publication Stats

780 Citations
172.01 Total Impact Points

Institutions

  • 2008-2015
    • University of Maryland, Baltimore
      • • Department of Epidemiology and Public Health
      • • Department of Medicine
      Baltimore, Maryland, United States
  • 2012-2014
    • Loyola University Maryland
      Baltimore, Maryland, United States
  • 2011
    • Baltimore City Health Department
      Baltimore, Maryland, United States