Methicillin-resistant Staphylococcus Aureus Acquisition Rate Research Articles

Analysis of the Trends of Methicillin-Resistant Staphylococcus aureus in Gauteng Public Hospitals from 2009 to 2018.

Most investigations into the distribution of methicillin resistant Staphylococcus aureus (MRSA) have focused exclusively on bloodborne infections within individual health care institutions for shorter time periods. This has limited the analysis of a community-spread pathogen to snapshots within the hospital domain. Therefore, in this study we determined the demographic and geographical patterns of MRSA infections and their fluctuation in 10 years within all public hospitals in Gauteng, South Africa. A retrospective analysis of S. aureus samples was done by deduplicating samples in two groups. The sample groups were placed into subsets with respect to demographic and geographical fields and compared across the studied period. Logistic regression was utilized to determine odds ratios for resistant infections in univariate and multivariable configurations. A total of 66,071 unique infectious events were identified from the 148,065 samples received over a 10-year period, out of which 14,356 were identified as bacteremia. MRSA bacteremia rates in Gauteng peaked in 2015 and have since decreased. Within Gauteng, metropolitan areas have the greatest burden of MRSA with children under 5 years of age and males being most affected. Medical wards have the highest S. aureus bacteremia rates, while intensive care units have the highest MRSA bacteremia rates. Patient age, admitting ward, and geographical district are the most important associated factors of resistance. MRSA acquisition rates have shown tremendous growth since 2009 but have since spiked and subsequently decreased. This may be due to the initiation of the National Guidelines on Antimicrobial Stewardship and Infectious Disease Surveillance. Further studies to determine the trajectory of infections are required to support these claims. IMPORTANCE S. aureus is the leading cause of a variety of devastating clinical conditions, including infective endocarditis, bacteremia, and pleuropulmonary infections. It is an important pathogen responsible for substantial morbidity and mortality. MRSA is a variant of interest originally responsible for difficult to treat hospital-acquired infections that has since achieved community spread throughout the world. Most investigations into the distribution of MRSA have focused exclusively on bloodborne infections within individual health care institutions for shorter periods. This has limited the analysis of a community-spread pathogen to snapshots within the hospital domain. This study sought to determine the demographic and geographical patterns of MRSA infections as well as how these have fluctuated over time within all public hospitals. This will also help in understanding the epidemiology and resistance trends of S. aureus, which will help clinicians to understand the clinical prospective and policy makers to design guidelines and strategies for treating such infections.

Modeling methicillin-resistant Staphylococcus aureus (MRSA) acquisitions in the intensive care unit with different staffing levels and finite direct-care tasks

Background: Modeling is a cost-effective way to evaluate interventions pertaining to hospital infection acquisitions, such as staffing levels. Increasing the number of nurses in an intensive care unit affects rates of HAI transmission. The way compartmental models are often formulated assumes that there is a never-ending series of tasks for workers to perform. Our previous models used a baseline of 1:3 nurse:patient ratio, and we kept the number of tasks the same across staffing ratios. We wanted to understand how having a finite number of tasks, using this baseline number, across staffing levels affected HAI acquisitions. Methods: We used a stochastic mathematical model of methicillin-resistant Staphylococcus aureus (MRSA) to study the impact of changes in staffing and a finite pool of tasks on hospital-associated acquisitions. For a 15-bed intensive care unit (ICU), we have 1 intensivist, and we set the nurse:patient ratios at 1:1, 1:1.5, 1:2.5, 1:3, 1:5, and 1:7.5, to represent the extreme ends of staffing levels and more moderate values in line with critical care society guidelines. Each model was run 1,000 times. The outcome of each scenario is the median number of hospital-associated MRSA acquisitions in 1 year from those 1,000 runs. Results: Treating the 1:3 nurse:patient ratio as the baseline, with 45 MRSA acquisitions per year, increasing the number of nurses from 5 to 6 (moving to a 1:2.5 nurse:patient ratio) had a relative risk (RR) of 0.77, suggesting that a small change in nurse staffing levels might have an outsized impact on rates. More dramatic changes had correspondingly larger swings in MRSA acquisition rates, with 1:1 nurse:patient ratio scenarios having an RR of 0.17, and at the other extreme, a 1:7.5 nurse:patient ratio having an RR of 4.66. Comparing the infinite to finite models, the ratios with more nurses had lower acquisition rates, with decreases ranging from 20% to 50%. Ratios with fewer nurses in the ICU showed 100%–400% increases in the number of acquisitions. All results were statistically significant. Conclusions: As nurse:patient ratios go up, the burden of direct-care tasks fall on fewer people, which has a direct impact on HAI rates. Our model demonstrates this hypothesis. Therefore, appropriate staffing should be considered in infection control guidelines, and the cost of staffing should be weighed against its impact on infection prevention as well as other areas of patient care. In this study, we considered only the impact from changes in contact patterns emerging from different staffing levels. Further insights may exist when considering other outcomes that also accompany increased staffing.Disclosures: None

173. Deciphering COVID-19-Associated Effects on Hospital MRSA Transmission and Social Networks

173. Deciphering COVID-19-Associated Effects on Hospital MRSA Transmission and Social Networks

Ward-level factors associated with methicillin-resistant Staphylococcus aureus acquisition-an electronic medical records study in Singapore.

Methicillin-Resistant Staphylococcus aureus (MRSA) is endemic in hospitals worldwide. Intrahospital transfers may impact MRSA acquisition risk experienced by patients. In this study, we investigated ward characteristics and connectivity that are associated with MRSA acquisition. We analysed electronic medical records on patient transfers and MRSA screening of in-patients at an acute-care tertiary hospital in Singapore to investigate whether ward characteristics and connectivity within a network of in-patient wards were associated with MRSA acquisition rates over a period of four years. Most patient transfers concentrated in a stable core network of wards. Factors associated with increased rate of MRSA acquisition were MRSA prevalence among patients transferred from other wards (rate ratio (RR): 7.74 [95% confidence interval (CI): 3.88, 15.44], additional 5 percentage point), critical care ward (RR: 1.72 [95% CI: 1.09, 2.70]) and presence of MRSA cohorting beds (RR: 1.39 [95% CI: 1.03, 1.90]. Oncology ward (RR: 0.66 [95% CI: 0.46, 0.94]) (compared to medical ward), and median length of stay (RR: 0.70 [95% CI: 0.55, 0.90], additional 1.5 days) were associated with lower acquisition rates. In addition, we found evidence of interaction between MRSA prevalence among patients transferred from other wards and weighted in-degree although the latter was not associated with MRSA acquisition after controlling for confounders. Wards with higher MRSA prevalence among patients transferred from other wards were more likely to have higher MRSA acquisition rate. Its effect further increased in wards receiving greater number of patients. In addition, critical care ward, presence of MRSA cohorting beds, ward specialty, and median length of stay were associated with MRSA acquisition.

Methicillin-Resistant Staphylococcus Aureus Bacteremia: Epidemiology, Clinical Characteristics, Risk Factors, and Outcomes in a Tertiary Care Center in Riyadh, Saudi Arabia.

BackgroundMethicillin-resistant Staphylococcus aureus (MRSA) has become increasingly common in hospitals worldwide. In an era of pandemics, it is important to understand all types of infectious diseases in order to control its outcome and reduce mortality rates related to it. This study aims to identify the epidemiology of MRSA bloodstream infection, risk factors, and mortality in King Abdulaziz Medical City in Riyadh.MethodsThis is a retrospective chart review study from January 2013 to June 2017. All patients with positive blood culture for MRSA at King Abdulaziz Medical City (KAMC), which is a tertiary care center in Riyadh, Saudi Arabia, were included. Data were extracted from electronic and paper medical records for patients who had a positive blood culture for MRSA. Data collected included demographics, microbiological details, risk factors, and 30-day mortality.ResultsFrom 2013 through June 2017, 633 Staphylococcus aureus bacteremia were reported in KAMC, of which 184 (29.1%) were MRSA with a mean age of 60±19 years. Almost all of our isolates were susceptible to vancomycin, linezolid, and tigecycline. The most common infectious syndrome these patients presented with was an endovascular infection which accounts for 30.4% while 19.9% presented as a case of pneumonia. The mortality within 30 days of collection of the positive blood culture was 20.65%. Male gender (OR = 2.33; 95% CI = 1.34-4.05; P-value = 0.003) and patients with history of recent hospital (OR = 2.34; 95% CI = 1.27-4.34; P-value = 0.007) or ICU (OR = 1.66; 95% CI = 1.09-2.52; P-value = 0.018) admissions were more likely to acquire MRSA.ConclusionsThe incidence of MRSA bacteremia at King Abdulaziz Medical City is high and increasing in conjunction with incidence rate posing a significantly high rate of mortality. Recent history of hospital admission, ICU admission and males were found to be significantly associated with higher rates of MRSA infection. Some modifiable risk factors that could be used to facilitate the reduction of MRSA acquisition rates is to avoid unnecessary hospital and ICU admissions.

Combining pulsed xenon ultraviolet disinfection with terminal manual cleaning helps reduce the acquisition rate of methicillin-resistant Staphylococcus aureus

The clinical effectiveness of ultraviolet light (UV) disinfection remains unclear. This study aimed to investigate the effect of adding pulsed xenon UV (PX-UV) disinfection to the terminal cleaning protocol on the rate of methicillin-resistant Staphylococcus aureus (MRSA) acquisition at a Japanese hospital. The use of a PX-UV disinfection device was added to the manual terminal cleaning protocol applied after the discharge or transfer of patients treated in the intensive and high care units. We used a Poisson regression model to examine the incidence of MRSA acquisition, based on the study period, PX-UV intervention status, unit type, and the rate of consumption of alcohol-based hand rub (ABHR). Approximately 86% of the rooms in the intervention units were terminally disinfected with the PX-UV device. In the intervention units, the incidence of MRSA acquisition decreased from 3.56 per 1,000 patient-days in the nonintervention period to 2.21 per 1,000 patient-days in the intervention period. Moreover, the use of PX-UV disinfection decreased the risk of MRSA acquisition (incident rate ratio: 0.556; 95% confidence interval, 0.309-0.999; P = .0497). ABHR consumption did not affect the risk of MRSA acquisition. Adding PX-UV disinfection to terminal manual cleaning reduced the rate of MRSA acquisition.

Intranasal Antiseptic and Universal Antiseptic Baths Are Effective in Reducing MRSA Acquisition in Extended-Care Facilities

Background: Methicillin-resistant Staphylococcus aureus (MRSA) is a growing clinical problem in rehabilitation hospitals, where patients stay for extended periods for intensive rehabilitation therapy. In addition to cutaneous sites, the nares could be a source for nosocomial MRSA transmission. Decolonization of nasal and cutaneous reservoirs could reduce MRSA acquisition. We evaluated the effectiveness of topical intranasal octenidine gel, coupled with universal chlorhexidine baths, in reducing MRSA acquisition in an extended-care facility. Methods: We conducted a quasi-experimental before-and-after study from January 2013 to June 2019. All patients admitted to a 100-bed rehabilitation hospital specialized in stroke and trauma care in Singapore were screened for MRSA colonization on admission. Patients screened negative for MRSA were subsequently screened at discharge for MRSA acquisition. Screening swabs were obtained from the nares, axillae, and groin and were cultured on selective chromogenic agar. Patients who tested positive for MRSA from clinical samples collected >3 days after admission were also considered to have hospital-acquired MRSA. Universal chlorhexidine baths were implemented throughout the study period. Intranasal application of octenidine gel for MRSA colonizers for use for 5 days from admission was added to the hospital’s protocol beginning in September 2017. An interrupted time series with segmented regression analysis was performed to evaluate the trends in MRSA acquisition before the intervention (January 2013–July 2017) and after the intervention (September 2017–June 2019) with intranasal octenidine. August 2017 was excluded from the analysis because the intervention commenced midmonth. Results: In total, 77 observational months (55 before the intervention and 22 after the intervention) were included. The mean monthly MRSA acquisition rates were 7.0 per 1,000 patient days before the intervention and 4.4 per 1,000 patient days after the intervention (P < .001), with a mean number of patient days of 2,516.3 per month before the intervention and 2,427.2 per month after the intervention (P = .0172). The mean monthly number of MRSA-colonized patients on admission to the hospital decreased from 24.8 before the intervention to 18.7 after the intervention (P < .001). Mean monthly hand hygiene compliance rate increased significantly from 65.7% before the intervention to 87.4% after the intervention (P < .001). After adjusting for the number of MRSA-colonized patients on admission and hand hygiene compliance rates, a constant trend was observed from January 2013 to July 2017 (adjusted mean coefficient, 0.012; 95% CI, −0.037 to 0.06), with an immediate drop in September 2017 (adjusted mean coefficient, −2.145; 95% CI, −0.248 to −0.002; P = .033), followed by a significant reduction in MRSA acquisition after the intervention from September 2017 through June 2019 (adjusted mean coefficient, −0.125; 95% CI, -4.109 to -0.181; P = .047). Conclusions: Topical intranasal octenidine, coupled with universal chlorhexidine baths, can reduce MRSA acquisition in extended-care facilities. Further studies should be conducted to validate the findings in other healthcare settings.Funding: NoneDisclosures: None

Assessing the Potential Impact of a Long-Acting Skin Disinfectant in the Prevention of MRSA

Background: Healthcare-associated transmission of methicillin-resistant Staphylococcus aureus (MRSA) remains a persistent problem despite advances in prevention. The use of chlorhexidine gluconate (CHG) as a means of decolonizing patients, either through targeted decolonization or daily bathing, is a frequently used measure to supplement other MRSA reduction interventions. However, there is room for new and innovative decolonizing agents. We explored the potential utility of a long-acting CHG-like disinfectant with a persistent protective effect as well as an immediate decolonizing action in the prevention of MRSA acquisition as well as the subsequent development of clinical illness and MRSA-related mortality. Methods: We modeled MRSA transmission throughout an 18-bed intensive care unit, based on previously published models. A baseline model with no daily decolonizing protocol was used as a baseline and was compared to a scenario assuming that patients were bathed with CHG, which decolonizes them but provides no ongoing protection, as well as a scenario involving a hypothetical treatment that both decolonizes and provides ongoing protection from subsequent colonization. We varied the duration and efficacy of this protection to fully explore the potential utility of such a treatment. Results: The results of the simulations are shown in Fig. 1, where duration and efficacy of protection varied. The number of MRSA acquisitions from each combination is depicted as a single point, with blue points indicating correspondingly fewer MRSA acquisitions. Overall, improved efficacy of the hypothetical disinfectant resulted in immediate improvements in MRSA acquisition rates when compared to the baseline. To see major improvements in the MRSA acquisition rate due to the duration of infection, that duration must be well above 10 hours in many scenarios. There is also little evidence of synergy between the two. Conclusions: Based on recent results suggesting CHG has a relatively modest per-use efficacy (<.20), there is room for improvement in the formulation and administration of decolonizing agents. Although there has been considerable excitement about the possibility of long-acting agents that not only decolonize but provide long-acting protection against colonization, these results suggest that such protection would only result in markedly decreased acquisition rates only if that duration of protection was extremely long, or if the agent itself was also considerably more efficacious than CHG. These results may be used to help consider the necessary study size for clinical studies of these agents in the future, or to set research priorities and properly calibrate expectations.Funding: NoneDisclosures: None

Impact of decolonization on methicillin-resistant Staphylococcus aureus transmission and infection in a neonatal intensive care unit.

The value of decolonization as a strategy for preventing methicillin-resistantStaphylococcus aureus (MRSA) in the neonatal intensive care unit (NICU) remains to be determined. After adding decolonization to further reduce MRSA transmission in our NICU, we conducted this retrospective review to evaluate its effectiveness. The review included patients who were admitted to our NICU between April 2015 and June 2018 and were eligible for decolonization including twice daily intranasal mupirocin and daily chlorhexidine gluconate bathing over 5 consecutive days. Patients were considered successfully decolonized if 3 subsequent MRSA screenings conducted at 1-week intervals were negative. The MRSA acquisition rate (AR) was calculated as hospital-acquired (HA) MRSA per 1,000 patient days (PD) and was used to measure the effectiveness of the decolonization. Of the 151 MRSA patients being reviewed, 78 (51.6%) were HA-MRSA, resulting in an overall AR of 1.27 per 1,000 PD. Between April 2015 and February 2016, when only the decolonization was added, the AR was 2.38 per 1,000 PD. Between March 2016 and June 2018 after unit added a technician dedicated to the cleaning of reusable equipment, the AR decreased significantly to 0.92 per 1,000 PD (P < .05). Of the 78 patients who were started on the decolonization, 49 (62.8%) completed the protocol, 11 (14.1%) remained colonized, and 13 (16.7%) were recolonized prior to NICU discharge. In a NICU with comprehensive MRSA prevention measures in place, enhancing the cleaning of reusable equipment, not decolonization, led to significant reduction of MRSA transmission.

Environmental disinfection with photocatalyst as an adjunctive measure to control transmission of methicillin-resistant Staphylococcus aureus: a prospective cohort study in a high-incidence setting

BackgroundEnvironmental disinfection with continuously antimicrobial surfaces could offer superior control of surface bioburden. We sought to decide the efficacy of photocatalyst antimicrobial coating in reducing methicillin-resistant Staphylococcus aureus (MRSA) acquisition in high incidence setting.MethodsWe performed prospective cohort study involving patients hospitalized in medical intensive care unit. A titanium dioxide-based photocatalyst was coated on high touch surfaces and walls. Five months of pre-intervention data were compared with five months of post-intervention data. The incidence rates of multidrug-resistant organism acquisition and the rates of hospital-acquired blood stream infection, pneumonia, urinary tract infection, and Clostridium difficile–associated diseases were compared using Cox proportional hazards regression analysis.ResultsIn total, 621 patients were included. There was significant decrease in MRSA acquisition rate after photocatalyst coating (hazard ratio, 0.37; 95% confidence interval, 0.14–0.99; p = 0.04). However, clinical identification of vancomycin-resistant Enterococcus spp. and multidrug-resistant Acinetobacter baumannii did not decrease significantly. The hazard of contracting hospital-acquired pneumonia during the intervention period compared to baseline period was 0.46 (95% confidence interval, 0.23–0.94; p = 0.03).ConclusionsIn conclusion, MRSA rate was significantly reduced after photocatalyst coating. We provide evidence that photocatalyst disinfection can be an adjunctive measure to control MRSA acquisition in high-incidence settings.Trial registrationISRCTN Registry (ISRCTN31972004). Registered retrospectively on November 19, 2018.

1149. Environmental Disinfection With Photocatalyst as an Adjunctive Measure to Control Multidrug-Resistant Organisms Transmission: A Prospective Cohort Study in High Incidence Setting

BackgroundHand hygiene and isolation precaution are often difficult to sustain, requiring additional measure to control multidrug-resistant organisms (MDRO) transmission. It was suggested that continuously antimicrobial surfaces could offer superior control of surface bioburden.Thus, we sought to decide the efficacy of photocatalyst antimicrobial coating in reducing MDRO acquisition in high incidence setting.MethodsAt an institute where used to have high incidence rate of methicillin-resistant Staphylococcus aureus (MRSA), we performed prospective cohort study involving patients hospitalized in medical intensive care unit. Five months of preintervention (where routine infection control measures were maintained) data were compared with 5 months of postintervention (after titanium dioxide-based photocatalyst were coated on high touch surfaces) data. The acquisition rate of MDROs and the rates of hospital acquired blood stream infection (BSI), pneumonia, urinary tract infection (UTI), and Clostridium difficile-associated disease (CDAD) were compared using Cox proportional hazards regression analysis.ResultsA total of 621 patients were included. There was significant decrease in MRSA acquisition rate after photocatalyst antimicrobial coating. (hazard ratio, 0.37; 95% CI, 0.14–0.99; P = 0.04.) However, acquisition rates of vancomycin-resistant Enterococcus spp. and multidrug-resistant Acinetobacter baunmannii had not significantly decreased. The hazard of acquiring hospital acquired pneumonia during intervention period compared with baseline period was 0.46 (95% CI, 0.23–0.94; P = 0.03). There were not significant reduction in hospital acquired BSI, UTI, and CDAD, after photocatalyst antimicrobial coating.ConclusionMRSA acquisition rate and hospital acquired pneumonia were significantly reduced after photocatalyst antimicrobial coating. This study provides evidence that photocatalyst antimicrobial disinfection can be an adjunctive measure to control MRSA acquisition in high incidence setting.Disclosures All authors: No reported disclosures.

Estimating the impact of post randomization changes in staff behavior in infection prevention trials: a mathematical modeling approach

BackgroundRandomized controlled trials (RCTs) of behavior-based interventions are particularly vulnerable to post-randomization changes between study arms. We assess the impact of such a change in a large, multicenter study of universal contact precautions to prevent infection transmission in intensive care units.MethodsWe construct a stochastic mathematical model of methicillin-resistant Staphylococcus aureus (MRSA) acquisition in a simulated 18-bed intensive care unit (ICU). Using parameters from a recent study of contact precautions that reported a post-randomization change in contact rates, with fewer visits observed in the treatment arm, we explore the impact of several possible interpretations of this change on MRSA acquisition rates.ResultsScenarios where contact precautions resulted in less patient visitation resulted in a mean decrease in MRSA acquisition rate of 37%, accounting for much of the effect reported in the trial.ConclusionsBehavior changes that impact the contact rate have the potential to drastically alter the results of RCTs in infection control settings. Careful monitoring for these changes, and an assessment of which changes will likely have the greatest impact on the study before the study begins are both recommended.

Intra-Facility Acquisition of Methicillin-Resistant Staphylococcus aureus (MRSA) in Southern Wisconsin Skilled Nursing Facilities

BackgroundStudies have shown that skilled nursing facilities (SNFs) are reservoirs for methicillin-resistant Staphylococcus aureus (MRSA). The extent to which resident-to-resident transmission accounts for the high burden of MRSA in these facilities remains poorly understood. The objective of this study was to estimate the frequency of intra-facility MRSA acquisition in a sample of SNFs participating in a longitduinal study in Wisconsin.MethodsMRSA colonization among a cohort of 449 subjects residing in six SNFs in Southern Wisconsin was measured using serial, multi-anatomical surveillance culturing. Phenotypic acquisitions events (i.e., MRSA [-] to MRSA[+]) were identified and further characterized both temporally (calendar date) and genetically (pulse-field gel electrophoresis). An intra-facility acquisition event was defined as incident recovery of an MRSA isolate that was genetically identical to at least one other strain previously recovered in a study facility. A Marascuilo procedure for comparing multiple proportions was employed to determine whether the proportion of intra-facility MRSA acquisitions differed across study facilities. Linear regression was employed to assess if certain facility-level characteristics were associated with rates of intra-facility MRSA acquisition.Results129 acquisition events were identified that met our criteria, of which 74 were determined to be intra-facility (57.4%) [95% CI: 45.5–67.6%]. Statistically significant differences were found between the intra-facility acquisition proportion of multiple SNFs. A facility’s baseline MRSA prevalence was significantly associated with its intra-facility MRSA acquisition rate (R2 = 0.784, P-value = 0.012).ConclusionIntra-facility acquisition represents a large proportion of the burden of MRSA observed in SNFs. The rate of intra-facility acquisition is variable between facilities but may, in part, be explained by the prevalent burden of MRSA in the facility (i.e., MRSA colonization pressure to characteristics of the facility). Whether other facility characteristics, including infection prevention practices are contributing to these transmission dynamics requires further study.Disclosures All authors: No reported disclosures.

Effect of daily chlorhexidine bathing on the acquisition of methicillin-resistant Staphylococcus aureus in a medical intensive care unit with methicillin-resistant S aureus endemicity.

Universal decolonization is recommended in intensive care units (ICUs) that have unacceptably high rates of methicillin-resistant Staphylococcus aureus (MRSA) despite implementation of basic prevention strategies. An interrupted time series study was performed to evaluate the effect of daily chlorhexidine bathing on the acquisition of MRSA in a medical ICU with MRSA endemicity. There was a 14-month control period and a 16-month chlorhexidine bathing period. Segmented Poisson regression analysis was performed to assess the impact of daily chlorhexidine bathing on the incidence density of MRSA. Also, chlorhexidine susceptibility testing with polymerase chain reaction for the qacA/B gene was performed on MRSA isolates collected during the chlorhexidine bathing period. There was a significant reduction in trend (-0.056; 95% confidence interval, -0.095 to -0.017; P = .005) of incidence density of MRSA despite a significant increase in both level and trend of MRSA prevalence rates during the chlorhexidine bathing period. However, there was no significant reduction in level of incidence density of MRSA during the interventional period. Minimum inhibitory concentration of chlorhexidine and the detection rates of the qacA/B gene for a total of 174 MRSA isolates did not increase during the chlorhexidine bathing period. Daily chlorhexidine bathing resulted in a significantly decreasing trend of MRSA acquisition rates irrespective of increased MRSA prevalence rates in the medical ICU. There was no shift of chlorhexidine-resistant MRSA strains.

Models to predict prevalence and transition dynamics of methicillin-resistant Staphylococcus aureus in community nursing homes

Recent spread of USA300 methicillin-resistant Staphylococcus aureus (MRSA) to nursing homes has been of particular concern. We sought to predict the ultimate prevalence of USA300 and non-USA300 MRSA and to examine the influence of potential risk factors on MRSA acquisition in community nursing homes. The data were collected during a longitudinal MRSA surveillance study that involved 449 residents in 6 community nursing homes in Wisconsin. The subjects were screened every 3 months for up to 1 year. Markov chain models were employed to predict strain-specific prevalence of MRSA at steady state, and to assess the influence of potential risk factors, including recent hospitalizations, invasive medical devices, and antibiotic exposure on MRSA acquisition rates and average duration of colonization. At steady state, 20% (95% confidence interval [CI], 15%-25%) of residents were predicted to remain colonized with non-USA300 and 4% (95% CI, 2%-7%) with USA300 MRSA. Residents who used antibiotics during the previous 3 months were twice more likely to acquire MRSA than those who did not (acquisition rates, 0.052; 95% CI, 0.038-0.075 and 0.025; 95% CI, 0.018-0.037, respectively). Non-USA300 was predicted to remain the dominant MRSA strain in community nursing homes. The higher rate of MRSA acquisition among residents with recent antibiotic exposure suggests that antibiotic stewardship may reduce MRSA colonization in this setting.

Hand Hygiene Promotion in a Hospital Setting through the WHO Multimodal Hand Hygiene Improvement Strategy

Background: This study evaluated the frequency and types of hand hygiene practices among healthcare workers directed by the WHO multimodal hand hygiene improvement strategy, and investigated the effect of hand hygiene practice on methicillin-resistant Staphylococcus aureus (MRSA) and vancomycin-resistant enterococci (VRE) isolation and MRSA acquisition rate and colonization pressure. Methods: A quasi-experimental study was performed at a tertiary care university hospital with 850 beds from January to September 2012. We assessed the hospital hand hygiene program using the WHO hand hygiene self-assessment framework. The WHO multimodal strategy was used for healthcare workers with low indexes, and the subjects were reassessed. Results: Hand hygiene compliance increased significantly from a pre-intervention rate of 58.7% to 72.6% post-intervention. MRSA and VRE isolation rates decreased from 1.69 per 1000 patient days to 1.41 and from 0.17 to 0.11, respectively. In intensive care units (ICUs), hand hygiene compliance rate rose to 77.9%, with a total score of 4.16 points out of 5 being awarded for the hand hygiene method, which was higher than that for the other care units. The pre-intervention MRSA acquisition rate in the ICU decreased from 7.47% to 4.30% post-intervention. This was associated with a decrease in the MRSA colonization pressure over the intervention period (26.2% to 16.9%). Conclusion: The utilization of the WHO multimodal strategy for improvement of hand hygiene increased the hand hygiene compliance rate and was effective in predicting a decreased rate of cross-infection, MRSA acquisition, and colonization pressure. We conclude that the implementation of such improvement strategies is crucial to maintaining hygiene standards and reducing infection within healthcare facilities.

Relationships Between the Importation, Transmission, and Nosocomial Infections of Methicillin-Resistant Staphylococcus aureus: An Observational Study of 112 Veterans Affairs Medical Centers

The study of hospital methicillin-resistant Staphylococcus aureus (MRSA) epidemiology is complicated by its transmissibility. Our objective was to understand how MRSA importation and transmission influence MRSA nosocomial infections in Veterans Affairs Medical Centers (VAMCs). We performed hospital-level analyses of acute-care MRSA admission prevalence, acquisition rates, and incident nosocomial clinical culture (INCC) rates, each a surrogate measure of importation, transmission, and nosocomial infection, respectively. We studied 112 VAMCs from October 2007 through September 2010, after the start of a bundled intervention including active surveillance for MRSA. We analyzed data using generalized linear mixed models. A total of 2.9 million surveillance tests were collected from 1.4 million patient admissions. Overall MRSA admission prevalence was 11.4%, acquisition was 5.2 per 1000 patient-days at risk, and INCC was 1.8 per 1000 patient-days at risk. A 10% increase in a hospital's average admission prevalence was associated with a 9.7% increase in its weekly acquisition rates (P < .001) and a 9.8% increase in its weekly INCC rates (P < .001). Significant decreases were observed in all 3 measures during the study period (P < .001). When INCC rates were stratified by nasal MRSA carriage at admission, a significant downward trend was observed only among those initially negative. Measured associations between MRSA admission prevalence, acquisition rate, and INCC rate were consistent with the hypothesis that decreased acquisition led to decreased importation, which in turn further abated acquisition. The downward trend in INCC rate specifically among individuals with negative admission surveillance tests suggests that decreasing transmission contributed to lower rates of nosocomial MRSA infection.

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

BackgroundThe relative contribution of long term care facilities (LTCFs) and hospitals in the transmission of methicillin-resistant Staphylococcus aureus (MRSA) is unknown.MethodsConcurrent 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.ResultsIn 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.ConclusionsOur 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.

Do Active Surveillance and Contact Precautions Reduce MRSA Acquisition? A Prospective Interrupted Time Series

BackgroundConsensus for methicillin-resistant Staphylococcus aureus (MRSA) control has still not been reached. We hypothesised that use of rapid MRSA detection followed by contact precautions and single room isolation would reduce MRSA acquisition.MethodsThis study was a pre-planned prospective interrupted time series comparing rapid PCR detection and use of long sleeved gowns and gloves (contact precautions) plus single room isolation or cohorting of MRSA colonised patients with a control group. The study took place in a medical-surgical intensive care unit of a tertiary adult hospital between May 21st 2007 and September 21st 2009. The primary outcome was the rate of MRSA acquisition. A segmented regression analysis was performed to determine the trend in MRSA acquisition rates before and after the intervention.FindingsThe rate of MRSA acquisition was 18.5 per 1000 at risk patient days in the control phase and 7.9 per 1000 at-risk patient days in the intervention phase, with an adjusted hazard ratio 0.39 (95% CI 0.24 to 0.62). Segmented regression analysis showed a decline in MRSA acquisition of 7% per month in the intervention phase, (95%CI 1.9% to 12.8% reduction) which was a significant change in slope compared with the control phase. Secondary analysis found prior exposure to anaerobically active antibiotics and colonization pressure were associated with increased acquisition risk.ConclusionContact precautions with single room isolation or cohorting were associated with a 60% reduction in MRSA acquisition. While this study was a quasi-experimental design, many measures were taken to strengthen the study, such as accounting for differences in colonisation pressure, hand hygiene compliance and individual risk factors across the groups, and confining the study to one centre to reduce variation in transmission. Use of two research nurses may limit its generalisability to units in which this level of support is available.

Molecular characterization of Methicillin-resistant Staphylococcus aureus from intensive care unit in Aberdeen Royal Infirmary, Scotland: Category: Lesson in Microbiology & Infection Control

Methicillin-resistant Staphylococcus aureus (MRSA) is a major cause of hospital-acquired infections which is often endemic on intensive care units (ICU) in the UK. Critically ill patients are at high risk of developing MRSA associated bacteraemia with a high mortality rate. MRSA strains are primarily transmitted through staff and the environment between the ICU patients. Up to 75% decrease in the rate of MRSA acquisition was reported after improved environmental hygiene in a UK ICU. Several typing methods have been used to study MRSA surveillance and epidemiology, e.g.