Kerri A Thom

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

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Publications (40)132.27 Total impact

  • [Show abstract] [Hide abstract]
    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.
    09/2014; 35(9):1156-1162.
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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.
    08/2014; 35(8):1060-1062.
  • 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: 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; · 9.37 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. 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: To determine the prevalence of Acinetobacter baumannii, an important healthcare-associated pathogen, among mechanically ventilated patients in Maryland. The Maryland MDRO Prevention Collaborative performed a statewide cross-sectional active surveillance survey of mechanically ventilated patients residing in acute care and long-term care (LTC) facilities. Surveillance cultures (sputum and perianal) were obtained from all mechanically ventilated inpatients at participating facilities during a 2-week period. All healthcare facilities in Maryland that provide care for mechanically ventilated patients were invited to participate. Mechanically ventilated patients, known to be at high risk for colonization and infection with A. baumannii, were included. Seventy percent (40/57) of all eligible healthcare facilities participated in the survey, representing both acute care ([Formula: see text]) and LTC ([Formula: see text]) facilities in all geographic regions of Maryland. Surveillance cultures were obtained from 92% (358/390) of eligible patients. A. baumannii was identified in 34% of all mechanically ventilated patients in Maryland; multidrug-resistant A. baumannii was found in 27% of all patients. A. baumannii was detected in at least 1 patient in 49% of participating facilities; 100% of LTC facilities had at least 1 patient with A. baumannii, compared with 31% of acute care facilities. A. baumannii was identified from all facilities in which 10 or more patients were sampled. A. baumannii is common among mechanically ventilated patients in both acute care and LTC facilities throughout Maryland, with a high proportion of isolates demonstrating multidrug resistance.
    Infection Control and Hospital Epidemiology 09/2012; 33(9):883-8. · 4.02 Impact Factor
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    ABSTRACT: BACKGROUND: Hand hygiene is considered a critical factor in the prevention of health care-associated infections, and there have been many studies on ways to measure hand hygiene compliance. OBJECTIVE: Our objective was to evaluate the utility of estimating hand hygiene compliance using automated count technology versus direct human observation before and after a feedback intervention. We used a before and after quasi-experimental study over 30 weeks, in the setting of one 12-bed neurocare intensive care unit (NCICU) and one 15-bed cardiac intensive care unit (CCU) in a university, tertiary care hospital. METHODS: We assessed hand hygiene through a quasi-experimental study comparing estimated compliance using automated count technology and direct observation by a secret shopper with a feedback intervention at month 3. We used Poisson segmented regression and χ(2) tests to compare trends before and after the intervention. RESULTS: Over 30 weeks, we collected 424,682 dispenser counts and 338 hours of human observations that included 1,783 room entries. Electronic hand hygiene dispenser counts increased significantly in the post-intervention period relative to the pre-intervention period (average count/patient-day increased 22.7 in the NCICU and 7.3 in the CCU, both P < .001), but direct observation of compliance did not change significantly (percent compliant increased by 2.9% in the NCICU and decreased by 6.7% in the CCU, P = .47 and P = .07, respectively). CONCLUSION: Passive electronic monitoring of hand hygiene dispenser counts does not closely correlate with direct human observation and was more responsive than observation to a feedback intervention.
    American journal of infection control 05/2012; · 3.01 Impact Factor
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    ABSTRACT: Best clinical practice aims to eliminate central line-associated blood stream infections (CLABSIs). However, CLABSIs still occur. This study's aim was to identify risk factors for CLABSI in the era of best practice. Critically ill surgical patients admitted over 2 years to the intensive care unit (ICU) for ≥ 4 days were studied. Patients with CLABSI as cause for ICU admission were excluded. Patients who developed CLABSI (National Healthcare Safety Network definition) were compared with those who did not. Hand hygiene, maximal sterile barriers, chlorhexidine scrub, avoidance of femoral vein, and proper maintenance were emphasized. Variables collected included demographics, diagnosis, and severity of illness using the Acute Physiology and Chronic Health Evaluation (APACHE) IV database and the hospital central data repository. Of 961 patients studied, 51 patients (5.2%) developed 59 CLABSIs. Mean time from ICU admission to CLABSI was 26 days ± 26 days. The CLABSI group was more likely to be male (odds ratio [OR] 1.93, 95% confidence interval [CI] 1.02-3.68), more critically ill on ICU admission (APACHE IV score 85.2 ± 21.9 vs. 65.6 ± 23.2, p < 0.01), more likely admitted to the emergency surgery service (OR 1.92, 95% CI 1.02-3.61), and had an association with reopening of recent laparotomy (OR 2.08, 95% CI 1.10-3.94). In the era of best practice, patients who develop CLABSI are clinically distinct from those who do not develop CLABSI. These CLABSIs may be due to deficiencies of the CLABSI definition or represent patient populations requiring enhanced prevention techniques. III, prognostic study.
    The journal of trauma and acute care surgery. 05/2012; 72(5):1174-80.
  • Clare Rock, Kerri Thom
    The Journal of the American Osteopathic Association 04/2012; 112(4):240.
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    ABSTRACT: No standardized guidelines exist for the biostatistical methods appropriate for studies evaluating diagnostic tests. Publication recommendations such as the STARD statement provide guidance for the analysis of data, but biostatistical advice is minimal and application is inconsistent. This article aims to provide a self-contained, accessible resource on the biostatistical aspects of study design and reporting for investigators. For all dichotomous diagnostic tests, estimates of sensitivity and specificity should be reported with confidence intervals. Power calculations are strongly recommended to ensure that investigators achieve desired levels of precision. In the absence of a gold standard reference test, the composite reference standard method is recommended for improving estimates of the sensitivity and specificity of the test under evaluation.
    European Journal of Clinical Microbiology 03/2012; 31(9):2111-6. · 3.02 Impact Factor

Publication Stats

318 Citations
132.27 Total Impact Points


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