OBJECTIVE Recerntly, the role of the healthcare network, defined as a set of hospitals linked by patient transfers, has been increasingly considered in the control of antimicrobial resistance. Here, we investigate the potential impact of nursing homes on the spread of antimicrobial-resistant pathogens across the healthcare network and its importance for control strategies. METHODS Based on patient transfer data, we designed a network model representing the Dutch healthcare system of hospitals and nursing homes. We simulated the spread of an antimicrobial-resistant pathogen across the healthcare network, and we modeled transmission within institutions using a stochastic susceptible-infected-susceptible (SIS) epidemic model. Transmission between institutions followed transfers. We identified the contribution of nursing homes to the dispersal of the pathogen by comparing simulations of the network with and without nursing homes. RESULTS Our results strongly suggest that nursing homes in the Netherlands have the potential to drive and sustain epidemics across the healthcare network. Even when the daily probability of transmission in nursing homes is much lower than in hospitals, transmission of resistance can be more effective because of the much longer length of stay of patients in nursing homes. CONCLUSIONS If an antimicrobial-resistant pathogen emerges that spreads easily within nursing homes, control efforts aimed at hospitals may no longer be effective in preventing nationwide outbreaks. It is important to consider nursing homes in planning regional and national infection control and in implementing surveillance systems that monitor the spread of antimicrobial resistance. Infect Control Hosp Epidemiol 2016;37:761-767.

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The Role of Nursing Homes in the Spread of Antimicrobial Resistance Over the Healthcare Network.

Infection is the leading cause of morbidity and the second leading cause of mortality in patients on renal replacement therapy. The rates of bloodstream infection in hemodialysis patients vary according to the type of venous access used. Gram-positive bacteria are most frequently isolated in blood cultures of hemodialysis patients. This study evaluated risk factors for the development of bloodstream infections in patients undergoing hemodialysis.

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Risk factors for bloodstream infection in patients at a Brazilian hemodialysis center: a case–control study

Multidrug-resistant organisms (MDRO) and in particular multidrug-resistant Gram-negative organisms (MRGN) are an increasing problem in hospital care. However, data on the current prevalence of MDRO in long-term care facilities (LTCFs) are rare. To assess carriage rates of MDRO in LTCF residents in the German Rhine-Main region, we performed a point prevalence survey in 2013. Swabs from nose, throat and perineum were analysed for meticillin-resistant Staphylococcus aureus (MRSA), perianal swabs were analysed for extended-spectrum beta-lactamase (ESBL)-producing organisms, MRGN and vancomycin-resistant enterococci (VRE). In 26 LTCFs, 690 residents were enrolled for analysis of MRSA colonisation and 455 for analysis of rectal carriage of ESBL/MRGN and VRE. Prevalences for MRSA, ESBL/MRGN and VRE were 6.5%, 17.8%, and 0.4%, respectively. MRSA carriage was significantly associated with MRSA history, the presence of urinary catheters, percutaneous endoscopic gastrostomy tubes and previous antibiotic therapy, whereas ESBL/MRGN carriage was exclusively associated with urinary catheters. In conclusion, this study revealed no increase in MRSA prevalence in LTCFs since 2007. In contrast, the rate of ESBL/MRGN carriage in German LTCFs was remarkably high. In nearly all positive residents, MDRO carriage had not been known before, indicating a lack of screening efforts and/or a lack of information on hospital discharge.

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Current prevalence of multidrug-resistant organisms in long-term care facilities in the Rhine-Main district, Germany, 2013

Background The spread of multidrug-resistant organisms (MDROs) is a global concern, and much about transmission in healthcare systems remains unknown. To reduce hospital stays, nursing facilities (NFs) have increasingly assumed care of post-acute populations. We estimate the prevalence of MDRO colonization in NF patients on enrollment and discharge to community settings, risk factors for colonization, and rates of acquiring MDROs during the stay. Methods We conducted a prospective, longitudinal cohort study of newly admitted patients in 6 NFs in southeast Michigan using active microbial surveillance of multiple anatomic sites sampled at enrollment, days 14 and 30, and monthly thereafter for up to 6 months. Results We enrolled 651 patients and collected 7526 samples over 1629 visits, with an average of 29 days of follow-up per participant. Nearly all participants were admitted for post-acute care (95%). More than half (56.8%) were colonized with MDROs at enrollment: methicillin-resistant Staphylococcus aureus (MRSA), 16.1%; vancomycin-resistant enterococci (VRE), 33.2%; and resistant gram-negative bacilli (R-GNB), 32.0%. Risk factors for colonization at enrollment included prolonged hospitalization (>14 days), functional disability, antibiotic use, or device use. Rates per 1000 patient-days of acquiring a new MDRO were MRSA, 3.4; VRE, 8.2; and R-GNB, 13.6. MDRO colonization at discharge was similar to that at enrollment (56.4%): MRSA, 18.4%; VRE, 30.3%; and R-GNB, 33.6%. Conclusions Short-stay NF patients exhibit a high prevalence of MDROs near the time of admission, as well as at discharge, and may serve as a reservoir for spread in other healthcare settings. Future interventions to reduce MDROs should specifically target this population.

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Longitudinal Assessment of Multidrug-Resistant Organisms in Newly Admitted Nursing Facility Patients: Implications for an Evolving Population.

Antimicrobial-resistant bacteria are either highly prevalent or increasing rapidly in Hong Kong and China. Treatment options for these bacteria are generally limited, less effective and more expensive. The emergence and dynamics of antimicrobial resistance genes in bacteria circulating between animals, the environment and humans are not entirely known. Nonetheless, selective pressure by antibiotics on the microbiomes of animal and human, and their associated environments (especially farms and healthcare institutions), sewage systems and soil are likely to confer survival advantages upon bacteria with antimicrobial-resistance genes, which may be further disseminated through plasmids or transposons with integrons. Therefore, antibiotic use must be tightly regulated to eliminate such selective pressure, including the illegalization of antibiotics as growth promoters in animal feed and regulation of antibiotic use in veterinary practice and human medicine. Heightened awareness of infection control measures to reduce the risk of acquiring resistant bacteria is essential, especially during antimicrobial use or institutionalization in healthcare facilities. The transmission cycle must be interrupted by proper hand hygiene, environmental cleaning, avoidance of undercooked or raw food and compliance with infection control measures by healthcare workers, visitors and patients, especially during treatment with antibiotics. In addition to these routine measures, proactive microbiological screening of hospitalized patients with risk factors for carrying resistant bacteria, including history of travel to endemic countries, transfer from other hospitals, and prolonged hospitalization; directly observed hand hygiene before oral intake of drugs, food and drinks; and targeted disinfection of high-touch or mutual-touch items, such as bed rails and bed curtains, are important. Transparency of surveillance data from each institute for public scrutiny provides an incentive for controlling antimicrobial resistance in healthcare settings at an administrative level.

Strategic measures for the control of surging antimicrobial resistance in Hong Kong and mainland of China.

The relative contribution of long term care facilities (LTCFs) and hospitals in the transmission of methicillin-resistant Staphylococcus aureus (MRSA) is unknown. Concurrent MRSA screening and spa type analysis was performed in LTCFs and their network hospitals to estimate the rate of MRSA acquisition among residents during their stay in LTCFs and hospitals, by colonization pressure and MRSA transmission calculations. In 40 LTCFs, 436 (21.6%) of 2020 residents were identified as ‘MRSA-positive’. The incidence of MRSA transmission per 1000-colonization-days among the residents during their stay in LTCFs and hospitals were 309 and 113 respectively, while the colonization pressure in LTCFs and hospitals were 210 and 185 per 1000-patient-days respectively. MRSA spa type t1081 was the most commonly isolated linage in both LTCF residents (76/121, 62.8%) and hospitalized patients (51/87, 58.6%), while type t4677 was significantly associated with LTCF residents (24/121, 19.8%) compared with hospitalized patients (3/87, 3.4%) (p < 0.001). This suggested continuous transmission of MRSA t4677 among LTCF residents. Also, an inverse linear relationship between MRSA prevalence in LTCFs and the average living area per LTCF resident was observed (Pearson correlation −0.443, p = 0.004), with the odds of patients acquiring MRSA reduced by a factor of 0.90 for each 10 square feet increase in living area. Our data suggest that MRSA transmission was more serious in LTCFs than in hospitals. Infection control should be focused on LTCFs in order to reduce the burden of MRSA carriers in healthcare settings.

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Transmission of methicillin-resistant staphylococcus aureus in the long term care facilities in Hong Kong

Disease surveillance is essential for studying disease spread. An important task in disease surveillance is identifying disease clusters, which are areas of unusually high incidence. In this paper, we formulate the disease surveillance problem as a clustering problem and review some standard techniques used for clustering problems. Inspired by techniques used in graph theory, we introduce our new method, which is based on a new statistic derived from minimal internal distance in the graph, to solve this problem. Simulated and real lung cancer data from New Mexico are analyzed according to our method, and results are compared with those of the popular spatial scan statistic.

Kris Baoqian Pan

Papers

Transmission of methicillin-resistant staphylococcus aureus in the long term care facilities in Hong Kong

Disease surveillance by clustering based on minimal internal distance