Kerri A Thom

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

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Publications (54)142.8 Total impact

  • [Show abstract] [Hide abstract]
    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.
    Infection Control and Hospital Epidemiology 11/2014; 35(11):1411-3. · 3.94 Impact Factor
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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.
    IDWeek 2014 Meeting of the Infectious Diseases Society of America; 10/2014
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    ABSTRACT: Background: Air sampling during outbreaks has demonstrated a potential for airborne transmission of Acinetobacter baumannii. The aim of this study was to assess air contamination with A. baumanniiin an endemic situation and to examine associated patient factors. Methods: This study was conducted in seven intensive care units at the University of Maryland Medical Center in Baltimore, Maryland, between May and December 2013. Patients with a culture positive for A. baumannii within the previous 5 days were identified. Air surrounding the patient was sampled for one hour, 3 feet from the head of the bed, using the Six-Stage Viable Andersen Cascade Impactor (ACI) (ThermoScientific). RambaCHROM™ Acinetobacter Agar plates were incubated at 37°C in ambient air for 24 hours. Patient factors such as presence of wounds, diarrhea and medical devices and antibiotic therapy were collected. Results: We sampled the rooms of 12 patients known to be colonized or infected with A. baumannii. Two colony forming units of A.baumannii were isolated in the air surrounding one patient. (Patient 1 on table below). The particles carrying A. baumannii were equal to or larger than 7.0µm in size. A. baumanniiwas not found in the air surrounding the remaining patients. The table below shows the characteristics of all patients sampled. Conclusion: We found that A. baumannii infrequently contaminated the air surrounding patients known to be colonized or infected with A. baumannii; many of whom were on a closed ventilation circuit. More studies need to be done to determine which patients are more likely to contaminate the surrounding air. Patient number Culture Site MDR Mechanical Ventilation Urinary catheter Central venous catheter Wound Diarrhea Antibiotics 1 * Sputum Catheter tip Yes Yes Yes Yes Yes Yes Yes 2 Sputum Peri-anal Yes No Yes No No No No 3 Sputum Yes No No No No Yes No 4 Sputum Yes Yes No No No yes No 5 Sputum No Yes Yes Yes No Yes Yes 6 Sputum No Yes Yes Yes Yes Yes Yes 7 Sputum Peri-anal Yes Yes Yes Yes No No Yes 8 Wound Yes No Yes Yes No No Yes 9 Sputum peri-anal Yes Yes Yes Yes No No Yes 10 Sputum No Yes No Yes Yes Yes Yes 11 Blood No Yes Yes Yes No No Yes 12 Sputum No Yes Yes No No No Yes *= Patient 1 had A. baumannii isolated from the surrounding air.
    IDWeek 2014 Meeting of the Infectious Diseases Society of America; 10/2014
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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.
    Infection Control and Hospital Epidemiology 09/2014; 35(9):1156-1162. · 3.94 Impact Factor
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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.
    Infection Control and Hospital Epidemiology 08/2014; 35(8):1060-1062. · 3.94 Impact Factor
  • Infection Control and Hospital Epidemiology 04/2014; 35(4):443-5. · 4.02 Impact Factor
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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.
    Infection Control and Hospital Epidemiology 04/2014; 35(4):426-9. · 4.02 Impact Factor
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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.
    Diagnostic microbiology and infectious disease 01/2014; · 2.45 Impact Factor
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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.
    American journal of infection control 12/2013; · 3.01 Impact Factor
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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.
    American journal of infection control 12/2013; · 3.01 Impact Factor
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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.
    IDWeek 2013 Meeting of the Infectious Diseases Society of America; 10/2013
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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.
    Infection Control and Hospital Epidemiology 09/2013; 34(9):984-6. · 4.02 Impact Factor
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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.
    American journal of infection control 07/2013; · 3.01 Impact Factor
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    ABSTRACT: Cancer patients are frequently immune suppressed and at risk for a wide range of opportunistic and healthcare-associated infections. A good infection prevention program is extremely important to reduce risk of infection. This review focuses on infection prevention measures specific to patients, healthcare personnel and visitors in the cancer center.
    Clinical Infectious Diseases 05/2013; · 9.42 Impact Factor
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    ABSTRACT: Objective. To determine whether enhanced daily cleaning would reduce contamination of healthcare worker (HCW) gowns and gloves with methicillin-resistant Staphylococcus aureus (MRSA) or multidrug-resistant Acinetobacter baumannii (MDRAB). Design. A cluster-randomized controlled trial. Setting. Four intensive care units (ICUs) in an urban tertiary care hospital. Participants. ICU rooms occupied by patients colonized with MRSA or MDRAB. Intervention. Extra enhanced daily cleaning of ICU room surfaces frequently touched by HCWs. Results. A total of 4,444 cultures were collected from 132 rooms over 10 months. Using fluorescent dot markers at 2,199 surfaces, we found that 26% of surfaces in control rooms were cleaned and that 100% of surfaces in experimental rooms were cleaned ([Formula: see text]). The mean proportion of contaminated HCW gowns and gloves following routine care provision and before leaving the rooms of patients with MDRAB was 16% among control rooms and 12% among experimental rooms (relative risk, 0.77 [95% confidence interval, 0.28-2.11]; [Formula: see text]). For MRSA, the mean proportions were 22% and 19%, respectively (relative risk, 0.89 [95% confidence interval, 0.50-1.53]; [Formula: see text]). Discussion. Intense enhanced daily cleaning of ICU rooms occupied by patients colonized with MRSA or MDRAB was associated with a nonsignificant reduction in contamination of HCW gowns and gloves after routine patient care activities. Further research is needed to determine whether intense environmental cleaning will lead to significant reductions and fewer infections. Trial registration. ClinicalTrials.gov identifier: NCT01481935.
    Infection Control and Hospital Epidemiology 05/2013; 34(5):487-93. · 4.02 Impact Factor
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    ABSTRACT: Objective. To quantify the association between admission to an intensive care unit (ICU) room most recently occupied by a patient positive for extended-spectrum β-lactamase (EBSL)-producing gram-negative bacteria and acquisition of infection or colonization with that pathogen. Design. Retrospective cohort study. Setting and Patients. The study included patients admitted to medical and surgical ICUs of an academic medical center between September 1, 2001, and June 30, 2009. Methods. Perianal surveillance cultures were obtained at admission to the ICU, weekly, and at discharge from the ICU. Patients were included if they had culture results that were negative for ESBL-producing gram-negative bacteria at ICU admission and had an ICU length of stay longer than 48 hours. Pulsed-field gel electrophoresis (PFGE) was performed on ESBL-positive isolates from patients who acquired the same bacterial species (eg, Klebsiella species or Escherichia coli) as the previous room occupant. Results. Among 9,371 eligible admissions (7,651 unique patients), 267 (3%) involved patients who acquired an ESBL-producing pathogen in the ICU; of these patients, 32 (12%) were hospitalized in a room in which the prior occupant had been positive for ESBL. Logistic regression results suggested that the prior occupant's ESBL status was not significantly associated with acquisition of an ESBL-producing pathogen (adjusted odds ratio, 1.39 [95% confidence interval, 0.94-2.08]) after adjusting for colonization pressure and antibiotic exposure in the ICU. PFGE results suggested that 6 (18%) of 32 patients acquired a bacterial strain that was the same as or closely related to the strain obtained from the prior occupant. Conclusions. These data suggest that environmental contamination may not play a substantial role in the transmission of ESBL-producing pathogens among ICU patients. Intensifying environmental decontamination may be less effective than other interventions in preventing transmission of ESBL-producing pathogens.
    Infection Control and Hospital Epidemiology 05/2013; 34(5):453-8. · 4.02 Impact Factor
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    ABSTRACT: We evaluated the prevalence of multidrug-resistant Acinetobacter baumannii environmental contamination before and after discharge cleaning in rooms of infected/colonized patients. 46.9% of rooms and 15.3% of sites were found contaminated precleaning, and 25% of rooms and 5.5% of sites were found contaminated postcleaning. Cleaning significantly decreased environmental contamination of A baumannii; however, persistent contamination represents a significant risk factor for transmission. Further studies on this and more effective cleaning methods are needed.
    American journal of infection control 12/2012; 40(10):1005-7. · 3.01 Impact Factor
  • Infection Control and Hospital Epidemiology 11/2012; 33(11):1177-8. · 4.02 Impact Factor
  • Kerri A Thom
    Infection Control and Hospital Epidemiology 11/2012; 33(11):1184. · 4.02 Impact Factor
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    ABSTRACT: Background: Central line associated bloodstream infection (CLABSI) intervention studies assess reduction in CLABSI rates as the primary outcome. However, even when defined by CDC standardized surveillance criteria, this measure involves some subjective judgment. Laboratory identified objective measures, such as total healthcare-associated bacteremia (HAB), could overcome potential assessment bias. Methods: We performed a retrospective study of laboratory detected bacteremia in all adult ICUs at our institution from July 2007-December 2011, using July 2009 as the start date for bundled interventions for CLABSI prevention. Major elements of the intervention were use of central line (CL) insertion checklists, education on appropriate blood culture methodology, aseptic CL maintenance, antimicrobial coated CLs, chlorhexidine dressings at CL exit sites, and neutral pressure needleless connectors. No other major infection prevention initiatives occurred during the study period. HAB was defined as laboratory detected bacteremia with onset > 48 hours after admission. Monthly rates of HAB/1000 patient-days, CLABSI/1000 CL days, and number of blood cultures obtained/ 1000 patient-days were evaluated over time, and before and after the intervention, using Quasi-Poisson regression. Results: Prior to the intervention, there was a slight non-significant increase per month in both mean CLABSI and HAB rates. Comparing post- to pre-intervention, there were strongly significant relative mean decreases in both CLABSI rate (5.4% per month, P < .001), and HAB rate (5.5% per month, P < .001). Adjusting for blood culture rates did not impact the effect of intervention on CLABSI rates, but did slightly attenuate the effect on HAB rates to a 2.2% relative decrease per month, though the change in slope remained strongly statistically significant (P < .001) (Figure 1). Conclusion: CLABSI reduction efforts were strongly associated with reduction in the rates of both CLABSI and total HAB in ICUs, and occurred independently of a decrease in the number of blood cultures obtained. This supports that the observed CLABSI reduction represents a true decrease rather than a result of assessment bias. Moreover, the HAB metric lends to automated surveillance without the need for resource intensive evaluation by infection preventionists.
    IDWeek 2012 Meeting of the Infectious Diseases Society of America; 10/2012

Publication Stats

408 Citations
142.80 Total Impact Points

Institutions

  • 2007–2014
    • University of Maryland, Baltimore
      • • Department of Epidemiology and Public Health
      • • Department of Medicine
      Baltimore, Maryland, United States
  • 2012
    • Johns Hopkins University
      • Department of Biostatistics
      Baltimore, Maryland, United States
  • 2010
    • University of Iowa
      Iowa City, Iowa, United States
  • 2008–2010
    • University of Maryland Medical Center
      • Department of Medicine
      Baltimore, Maryland, United States