Healthcare-Associated Infection and Exposure to Infected or Colonized Concurrent Roommates and Prior Bed Occupants

This dissertation examines factors associated with healthcare-associated infections (HAIs) in four acute care hospitals located in New York City. Specifically, this investigation focuses on the role that the physical environment plays with regard to patient-to-patient transmission. The initial analyses describe the scope of the problem by reporting the incidence of HAIs and antimicrobial resistance over a seven-year period in the study institutions. In total, 19,052 HAIs were identified among 761,426 discharges. HAI rates fell over time within all hospitals and for all organisms and infection types included in the study, and the odds of acquiring an HAI decreased significantly over time for all organisms. Resistance levels were stable for Enterococcus spp., Staphylococcus aureus, Acinetobacter baumannii, and Streptococcus pneumoniae. Multidrug resistance increased for Pseudomonas aeruginosa and decreased for Klebsiella pneumoniae, though imipenem resistance among K. pneumoniae climbed sharply in 2011. A systematic literature review is presented to summarize what is known and unknown about how patients’ exposure to infected or colonized concurrent roommates and prior bed occupants affects their risk of developing HAIs. Eighteen articles meeting the inclusion criteria were identified. More than half reported at least one statistically significant positive association between the infection/colonization status of a roommate or previous room occupant and the development of HAIs. Only a single article identified a statistically significant negative association. The remainder found no associations that reached statistical significance, though this may be due to the fact that they were insufficiently powered. The dissertation concludes with a matched case-control study designed to quantify the association between having a prior bed occupant or roommate with a positive blood, respiratory, urine, or wound culture and subsequent infection with the same organism. In a multivariable analysis controlling for patient characteristics and mutually controlling for each exposure, the odds of being exposed to a prior bed occupant with the same organism were 5.83 (95% Confidence Interval [3.62, 9.39]) times greater for cases versus controls and the odds of being exposed to a roommate with the same organism were 4.82 [3.67, 6.34] times greater

Changes in the incidence and antimicrobial susceptibility of healthcare-associated infections in a New York hospital system, 2006-2012

Introduction:  National efforts to curtail healthcare-associated infections (HAI) proliferated recently, though data detailing progress over time are limited.  This retrospective cohort study aims to describe changes in incidence and antimicrobial susceptibility of HAI in four New York City hospitals over seven years.  Methods:  Electronic data were collected retrospectively for all patients discharged from 2006 through 2012.  Previously validated computerized algorithms based on National Healthcare Safety Network criteria detected bloodstream infections, pneumonia, surgical site infections, and urinary tract infections with Enterococcus spp., Staphylococcus aureus, Streptococcus pneumoniae, Acinetobacter baumannii, Pseudomonas aeruginosa and Klebsiella pneumoniae.  Antimicrobial susceptibilities were obtained from electronic laboratory records.  Logistic regression was used to assess changes in odds of acquiring an HAI and odds of antimicrobial resistance over time, controlling for age, gender, severity of illness, previous hospitalizations, and admission source.  Results:  In total, 19,052 HAI were identified among 761,426 discharges.  HAI rates fell for all organisms, all infection types, and within all hospitals.  Odds of acquiring an HAI decreased significantly over time for all organisms.  Resistance levels were stable for Enterococcus spp., S. aureus, A. baumannii, and S. pneumoniae.  Multidrug resistance increased for P. aeruginosa and decreased for K. pneumoniae, though imipenem resistance among K. pneumoniae climbed sharply in 2011.  Conclusions:  This study suggests that HAI incidence rates are falling, possibly due to increased federal, state and local attention to healthcare quality and patient safety.  Though we found no substantial reductions in resistance, recent national attention towards antimicrobial stewardship may precipitate a change in coming years

High-Throughput Screening Platform for Engineered Nanoparticle-Mediated Genotoxicity Using CometChip Technology

The likelihood of intentional and unintentional engineered nanoparticle (ENP) exposure has dramatically increased due to the use of nanoenabled products. Indeed, ENPs have been incorporated in many useful products and have enhanced our way of life. However, there are many unanswered questions about the consequences of nanoparticle exposures, in particular, with regard to their potential to damage the genome and thus potentially promote cancer. In this study, we present a high-throughput screening assay based upon the recently developed CometChip technology, which enables evaluation of single-stranded DNA breaks, abasic sites, and alkali-sensitive sites in cells exposed to ENPs. The strategic microfabricated, 96-well design and automated processing improves efficiency, reduces processing time, and suppresses user bias in comparison to the standard comet assay. We evaluated the versatility of this assay by screening five industrially relevant ENP exposures (SiO[subscript 2], ZnO, Fe[subscript 2]O[subscript 3], Ag, and CeO[subscript 2]) on both suspension human lymphoblastoid (TK6) and adherent Chinese hamster ovary (H9T3) cell lines. MTT and CyQuant NF assays were employed to assess cellular viability and proliferation after ENP exposure. Exposure to ENPs at a dose range of 5, 10, and 20 μg/mL induced dose-dependent increases in DNA damage and cytotoxicity. Genotoxicity profiles of ZnO > Ag > Fe[subscript 2]O[subscript 3] > CeO[subscript 2] > SiO[subscript 2] in TK6 cells at 4 h and Ag > Fe[subscript 2]O[subscript 3] > ZnO > CeO[subscript 2] > SiO[subscript 2] in H9T3 cells at 24 h were observed. The presented CometChip platform enabled efficient and reliable measurement of ENP-mediated DNA damage, therefore demonstrating the efficacy of this powerful tool in nanogenotoxicity studies.National Science Foundation (U.S.) (Grant 1235806)National Institutes of Health (U.S.) (Grant P30ES000002

Incidence, Risks, and Types of Infections in Pediatric Long-term Care Facilities

Importance: The population of infants, children, and adolescents cared for at pediatric long-term care facilities is increasing in complexity and size and thus consumes substantial health care resources. Infections are a significant cause of morbidity and mortality in this population, but few recent data describe their incidence and effects. Objectives: To describe the types of infections diagnosed in residents of pediatric long-term care facilities, calculate infection rates, and identify risk factors for respiratory tract infections (RTIs). Design, Setting, and Participants: This prospective cohort study, which was part of a larger trial called Keep It Clean for Kids, was conducted from September 1, 2012, to December 31, 2015, at 3 pediatric long-term care facilities in New York. Residents of the facilities who were 21 years or younger and either residents or admitted during the study period (n = 717) were enrolled in the study. Medical records were reviewed to identify infections diagnosed by site clinicians. Main Outcomes and Measures: Incidence of infections, such as RTIs; skin and soft-tissue infections; chronic comorbid conditions, including neurologic and respiratory disorders; and device use, including gastrostomy tubes and tracheostomies, was determined. Risk factors for RTIs were assessed by generalized linear mixed method regression modeling. Results: The 717 residents had a median (interquartile range) age at enrollment of 2.6 (0.4-9.1) years; 358 (49.9%) were male. Four hundred twenty-eight residents (59.7%) had feeding tubes and 215 (30.0%) had tracheostomies. Most chronic comorbid conditions were musculoskeletal or ambulation (532 residents [74.2%]), neurologic (505 [70.4%]), respiratory (361 [50.3%]), and gastrointestinal (230 [32.1%]) disorders, and 460 residents (64.2%) had 4 or more chronic comorbid conditions. Site clinicians diagnosed 2052 infections during the 3-year study period. Respiratory tract infections were most common and were diagnosed in 1291 residents (62.9%). The overall infection rate was 5.3 infections per 1000 resident-days, and RTI rates were 3.3 infections per 1000 resident-days. Overall infection rates and rates of RTI, skin and soft-tissue infection, urinary tract infection, and bloodstream infection varied among the 3 sites. In the multivariable model, younger age (incidence rate ratio [IRR], 1.05; 95% CI, 1.03-1.06), increased number of chronic comorbid conditions (IRR, 1.12; 95% CI, 1.06-1.19), and the use of feeding tubes (IRR, 1.34; 95% CI, 1.03-1.64) and tracheostomies (IRR, 1.40; 95% CI, 1.17-1.69) were associated with RTIs. Conclusions and Relevance: In this study, RTIs were the most common infections diagnosed, but modifiable risk factors for RTIs were not identified. Future work should focus on optimizing infection prevention and control strategies to reduce infections, particularly RTIs, in the pediatric long-term care population

Burden of present-on-admission infections and health care-associated infections, by race and ethnicity

Background: In the United States incidence of sepsis and pneumonia differ by race, but it is unclear whether this is due to intrinsic factors or health care factors. Methods: We conducted a study of 52,006 patients hospitalized during 2006-2008 at a referral hospital in upper Manhattan. We examined how the prevalence of present-on-admission and health care-associated infection compared between non-Hispanic blacks, Hispanics, and non-Hispanic whites adjusting for sociodemographic factors, admission through the emergency department, and comorbid conditions. Results: Non-Hispanic blacks had 1.59-fold (95% confidence interval [CI], 1.29-1.96) and 1.55-fold (95% CI, 1.35-1.77) risk of community-acquired bloodstream infection and urinary tract infection compared with non-Hispanic whites. Hispanic patients had 1.31-fold (95% CI, 1.15-1.49) risk of presenting with community-acquired urinary tract infection compared with non-Hispanic whites. Controlling for admission through the emergency department, comorbidity, and neighborhood income attenuated the differences in prevalence of infections. Conclusions: We found that health disparities in present-on-admission infections might be largely explained by potential lack of ambulatory care, socioeconomic factors, and comorbidity

Risk factors for hospital-acquired antimicrobial-resistant infection caused by Acinetobacter baumannii

Background Acinetobacter baumannii can cause serious healthcare-associated infections (HAIs) and the incidence is increasing, with many strains now resistant to multiple antibiotic classes. The aims of this study were to examine factors associated with HAIs caused by antimicrobial-resistant as compared with antimicrobial-susceptible strains of A. baumannii and to investigate trends in the incidence of resistance over time. Electronic data from two U.S. hospitals in a large urban healthcare system in over the years 2006–2012 were used for the analysis. Multiple logistic regression was used to explore risk factors for infection with A. baumannii resistant to ampicillin or ampicillin/sulbactam in the bloodstream, urinary tract, and respiratory tract. The Cochran-Armitage trend test was used to explore resistance trends over time. Findings A total of 671 adults with first-time A. baumannii infection were included in the analysis; 302 isolates (45 %) were resistant to ampicillin or ampicillin/sulbactam and 369 (55 %) were susceptible. In the multivariable analysis, significant risk factors included longer length of stay prior to infection (Odds Ratio [OR] = 1.03; 95 % Confidence Interval [CI]: 1.01, 1.04), hospital A versus B (OR = 0.35; 95 % CI: 0.13, 0.93), and antibiotic use prior to infection (OR = 2.88; 95 % CI: 1.02, 8.13). Resistance was more common in respiratory infections (OR = 2.96; 95 % CI: 1.04, 8.44). No trend was found between year of infection and resistance. Conclusions The risk factors we identified are consistent with previous findings, but we found no evidence in this population that resistance to ampicillin or ampicillin/sulbactam was increasing over time

Personal and Household Hygiene, Environmental Contamination, and Health in Undergraduate Residence Halls in New York City, 2011

Background: While several studies have documented the importance of hand washing in the university setting, the added role of environmental hygiene remains poorly understood. The purpose of this study was to characterize the personal and environmental hygiene habits of college students, define the determinants of hygiene in this population, and assess the relationship between reported hygiene behaviors, environmental contamination, and health status. Methods: 501 undergraduate students completed a previously validated survey assessing baseline demographics, hygiene habits, determinants of hygiene, and health status. Sixty survey respondents had microbiological samples taken from eight standardized surfaces in their dormitory environment. Bacterial contamination was assessed using standard quantitative bacterial culture techniques. Additional culturing for coagulase-positive Staphylococcus and coliforms was performed using selective agar. Results: While the vast majority of study participants (n = 461, 92%) believed that hand washing was important for infection prevention, there was a large amount of variation in reported personal hygiene practices. More women than men reported consistent hand washing before preparing food (p = .002) and after using the toilet (p = .001). Environmental hygiene showed similar variability although 73.3% (n = 367) of subjects reported dormitory cleaning at least once per month. Contamination of certain surfaces was common, with at least one third of all bookshelves, desks, refrigerator handles, toilet handles, and bathroom door handles positive for <10 CFU of bacteria per 4 cm2 area. Coagulase-positive Staphylococcus was detected in three participants' rooms (5%) and coliforms were present in six students' rooms (10%). Surface contamination with any bacteria did not vary by frequency of cleaning or frequency of illness (p<.05). Conclusions: Our results suggest that surface contamination, while prevalent, is unrelated to reported hygiene or health in the university setting. Further research into environmental reservoirs of infectious diseases may delineate whether surface decontamination is an effective target of hygiene interventions in this population

Transmission of health care-associated infectionsfrom roommates and prior room occupants:a systematic review

Pathogens that cause health care-associated infections (HAIs) are known to survive on surfaces and equipment in health care environments despite routine cleaning. As a result, the infection status of prior room occupants and roommates may play a role in HAI transmission. We performed a systematic review of the literature evaluating the association between patients’ exposure to infected/colonized hospital roommates or prior room occupants and their risk of infection/colonization with the same organism. A PubMed search for English articles published in 1990–2014 yielded 330 studies, which were screened by three reviewers. Eighteen articles met our inclusion criteria. Multiple studies reported positive associations between infection and exposure to roommates with influenza and group A streptococcus, but no associations were found for Clostridium difficile, methicillin-resistant Staphylococcus aureus, Cryptosporidium parvum, or Pseudomonas cepacia; findings were mixed for vancomycin-resistant enterococci (VRE). Positive associations were found between infection/colonization and exposure to rooms previously occupied by patients with Pseudomonas aeruginosa and Acinetobacter baumannii, but no associations were found for resistant Gram-negative organisms; findings were mixed for C. difficile, methicillin-resistant S. aureus, and VRE. Although the majority of studies suggest a link between exposure to infected/colonized roommates and prior room occupants, methodological improvements such as increasing the statistical power and conducting universal screening for colonization would provide more definitive evidence needed to establish causality

Temporal trends and risk factors for extended-spectrum beta-lactamase-producing Escherichia coli in adults with catheter-associated urinary tract infections

Extended-spectrum beta-lactamase (ESBL)-producing Escherichia coli cause up to 10% of catheter-associated urinary tract infections (CAUTI). We report changes in ESBL prevalence among CAUTIs in an adult acute care hospital from 2006-2012 and describe factors associated ESBL-production among E. coli CAUTI. Data on patients ≥18 years discharged from a 647-bed tertiary/quaternary care hospital (2006-2012), a 221-bed community hospital (2007-2012), and a 914-bed tertiary/quaternary care hospital (2008) were obtained retrospectively from an electronic database (N = 415,430 discharges). Infections were identified using a previously validated electronic algorithm. Information on medical conditions and treatments were collected from electronic health records and discharge billing codes. A case-control design was used to determine factors associated with having a CAUTI caused by an ESBL-producing E. coli versus a non-ESBL-producing E. coli. Changes in yearly proportion of ESBL E. coli CAUTI at the 647-bed tertiary/quaternary care hospital were evaluated. ESBL increased from 4% in 2006 to 14% in 2012, peaking at 18% in 2009. Prior antibiotic treatment and urinary tract disease significantly increased odds of ESBL. This study provides evidence that treatment with beta-lactam and non-beta-lactam antibiotics is a risk factor for acquiring ESBL-producing E. coli CAUTI, and the prevalence of this organism may be increasing in acute care hospitals