Re-evaluating microbiological testing and isolation measures for suspected MRSA carriers: insights from a retrospective study in a Dutch tertiary care center.

Background: Methicillin-resistant Staphylococcus aureus (MRSA) is a common pathogen in the intensive care unit (ICU). Active surveillance cultures (ASCs) for MRSA are often performed in ICUs; however, they may not be optimal in ICUs with a low MRSA prevalence. This study aims to determine the risk factors of MRSA carriage in the ICU and develop a clinical predictive model to optimize the screening process.Methods: All patients who were admitted to the ICU between April 2015 and August 2022 were retrospectively included in this study. At the time of ICU admission, all patients underwent MRSA screening using nasal ASCs. Based on the screening results, patients were categorized into MRSA-positive and MRSA-negative groups. Patients' characteristics were evaluated to determine the prevalence of MRSA and the risk factors. Cost analysis was conducted based on the risk factors identified by our analysis.Results: Of the 3927 ICU patients included, 133 (3.4%) were MRSA-positive. Multivariate analyses showed that risk factors for MRSA carriage were age ≥ 50 years (odds ratio [OR]: 2.11), history of hospitalization within a year (OR: 1.50), and ICD-10 codes classification I, IV, and XII (OR: 4.98). Screening patients based on at least one of the risk factors exhibited high sensitivity (96.9%) to identifying MRSA carriage and could reduce ASC overall costs by 10.9%, equivalent to $4686.Conclusion: This study suggests that universal ASCs to detect MRSA may not be optimal in ICU settings with a low prevalence of MRSA. Targeted screening based on risk factors may reduce the volume and cost of MRSA screening. Prospective multicenter studies are warranted to validate these findings and to assess the generalizability of the proposed screening strategy.

132 Non-respiratory swabs have little role in the detection of methicillin resistant Staphylococcus aureus in cystic fibrosis

Background: Methicillin-resistant Staphylococcus aureus (MRSA) infection in neonates is associated with significant morbidity, mortality, and hospital cost. Multiple studies have shown that these infections are often preceded by colonization, but no consensus has been established for MRSA surveillance. The impact of changing the surveillance strategy on vancomycin utilization has not been evaluated previously. Methods: Retrospective chart review of infants who underwent MRSA screening in a level IV NICU with all outborn neonates. A weekly surveillance PCR was obtained from the nares between July 2016 and June 2017 (phase 1) and only on admission and discharge between July 2017 and June 2018 (phase 2). Patients with a positive PCR were placed on contact precautions without decolonization. The χ2 test was performed to compare the 2 phases of screening, and the Student t test and the Fisher exact test were used to compare the characteristics of MRSA colonized infants. Vancomycin utilization was measured in days of therapy (DOT) per 1,000 NICU patient days. Results: In total, 689 infants underwent MRSA screening during the study period; 324 infants had weekly MRSA surveillance and 365 infants had screening at admission and discharge. There was no statistically significant difference in MRSA colonization rates (4.3% vs 3.0%) or MRSA colonization acquisition (negative to positive, 1.8% vs 1.0%) between the phases. Among MRSA-colonized patients, nearly 60% were colonized on admission. Nearly 40% of the infants became colonized with MRSA during their hospitalization, none of whom developed MRSA infections prior to discharge. Mean vancomycin utilization decreased from 38.55 to 30.16 DOT per 1,000 NICU patient days between the 2 study periods. Conclusions: In a level IV NICU with relatively low MRSA prevalence, the change in MRSA screening practice from weekly surveillance to surveillance upon admission and discharge demonstrated no difference in MRSA acquisition or infection. Overall vancomycin utilization also decreased during this period, suggesting a culture shift around antibiotic utilization. Further study is needed to evaluate the utility of MRSA screening, decolonization, and isolation practices in low-prevalence NICUs and to identify additional drivers of vancomycin utilization.Funding: NoneDisclosures: None

The problem of the spread of methicillin-resistant Staphylococcus aureus (MRSA) during hospital transfers, re-admission and admission from nursing homes is well documented. Since MRSA carriage can be occult, only to be detected later in clinical specimens, screening at hospital admission has been advocated for areas in which MRSA is endemic [1]. In a previous study Troillet et al. [2] found that without admission screening half of the MRSA carriers whose status was unknown at admission would have been missed or detected late. Compared with no screening, targeted screening has been shown to be effective in reducing the rates of MRSA acquisition in hospitals with a high level of endemic MRSA [3]. In Hong Kong, MRSA has been endemic since the mid-1980s [4]. Currently, screening for MRSA at admission is only practiced in a few selected units. The present report details the experience gained at an acutecare hospital in Hong Kong (Northern District Hospital) where screening for MRSA at admission is practiced routinely. The data was obtained by retrospectively reviewing the culture results in the hospital’s mainframe computer and the infection control records over a 3-year period (1 January 1999–31 December 2001). The 600bed hospital has all of the major specialty services, including an intensive care unit and a 24-h emergency department. The hospital’s screening policy called for cultures to be performed within 24 h for all patients with one or more of the following risk factors: a history of MRSA carriage, nursing home residence or any previous hospitalization (including inter-hospital transfer) during the preceding 6 months. Patients were grouped together and isolation precautions were implemented until the results of screening were available [1]. Screening cultures were also performed before the start of hospital duty for all new healthcare workers whose jobs involved close patient contact. During the study period, compliance with the MRSA screening policy was monitored regularly by ward visits and chart review, and it was estimated to exceed 90%. In order to obtain a background rate of MRSA carriage, 600 patients without the above risk factors for MRSA were prospectively screened at the emergency department for 3 months (August–November 2000) using the same protocol. An average of 10 patients per day was screened. To facilitate data retrieval and auditing, codes were entered into the laboratory records of all screened patients and healthcare workers. Initial and follow-up samples were coded separately. Individual risk factors were not coded separately until 1 June 2001. Hence, a breakdown of the MRSA isolation rate according to individual risk factors was available only for the period 1 June–31 December 2001. As part of the infection control policy, all patients and staff members who tested positive for MRSA during screening were treated topically for 5 days with a daily wash or bath using 4% chlorhexidine gluconate (Hibiscrub; Zeneca Pharma, France) and the twice-daily application of 2% mupirocin (Bactroban nasal; GlaxoSmithKline, Hong Kong) to both nares. Follow-up MRSA cultures were performed weekly for 3 weeks following T. L. Que · K. T. Yip · H. L. Ng New Territory North Pathology Service, Northern District Hospital, Hong Kong SAR, People’s Republic of China

Background Methicillin-resistant Staphylococcus aureus (MRSA) is one of the most common pathogens in the intensive care unit (ICU). Active surveillance cultures (ASCs) for MRSA often performed in ICUs may not be optimal in ICU settings with low prevalence of MRSA. This study aims to determine the risk factors of MRSA carriage in the ICU and develop a clinical predictive model to optimize the screening process. Methods All patients screened for MRSA by nasal ASC at the time of ICU admission between April 2015 and August 2022 were retrospectively included and divided into MRSA-positive and MRSA-negative groups. Patients’ characteristics were evaluated to determine the prevalence of MRSA and the risk factors. Cost analysis was conducted based on the risk factors identified by our analysis. Results Of the 3,927 ICU patients included, 133 (3.4%) were MRSA-positive. Multivariate analyses showed that risk factors for MRSA carriage were age ≥60 years (odds ratio [OR]: 1.60), history of hospitalization within a year (OR: 1.51), admission under departments dealing with skin and soft tissues (OR: 3.00), and ICD-10 codes classification I (OR: 3.44). Screening patients based on at least one of the risk factors exhibited high sensitivity (93.2%) to identifying MRSA carriage and could reduce ASC overall costs by 86.9%. Conclusion This study suggests that universal ASCs to detect MRSA may not be optimal in ICU settings with low prevalence of MRSA. Targeted screening based on risk factors may reduce the volume and cost of MRSA screening. Prospective studies are warranted to confirm these findings. Disclosures All Authors: No reported disclosures

Screening for methicillin-resistant Staphylococcus aureus (MRSA) represents a worldwide public health priority. Screening patients to detect colonization is considered an essential pillar of any MRSA control program. To (a) assess health care workers' (HCWs) attitudes, social norms, perceived behavioral control toward MRSA screening, and intention to perform the screening; (b) examine the predictors of HCWs intentions to perform screening; (c) identify HCWs' perception of barriers to and benefits of screening; and (d) identify HCWs' information sources about screening. Data obtained from 870 HCWs using the MRSA Screening Survey (MRSASS) were analyzed. The MRSASS was divided into three parts. Part 1 assessed sociodemographic variables. Part 2 contained the following six sections: (a) attitudes and perceived risk of MRSA screening, (b) perceived social norms of screening, (c) perceived behavioral control factors, (d) intention, (e) barriers to screening, and (f) benefit of screening. Part 3 assessed HCWs' source of information about MRSA screening. HCWs had positive attitudes toward the intention to screen for MRSA. Many HCWs felt that they had little influence on policy makers to conduct MRSA screening. The most reported barriers for MRSA screening were a lack of isolation facilities and increased workload. Only 5.2% (n = 45) of respondents indicated that they had been given MRSA screening training. Attitude was the only predictor for the intention to screen for MRSA. HCWs believed that the barriers to MRSA screening were inadequate facilities, primarily the lack of isolation facilities, and increased workload.

Joint Healthcare Infection Society (HIS) and Infection Prevention Society (IPS) guidelines for the prevention and control of meticillin-resistant Staphylococcus aureus (MRSA) in healthcare facilities

To estimate the proportion of patients who acquire methicillin-resistant Staphylococcus aureus (MRSA) while in hospital and to identify risk factors associated with acquisition of MRSA. Retrospective cohort study. Adult patients discharged from 36 general specialty wards of 2 Scottish hospitals that had implemented universal screening for MRSA on admission. Patients were screened for MRSA on discharge from hospital by using multisite body swabs that were tested by culture. Discharge screening results were linked to admission screening results. Genotyping was undertaken to identify newly acquired MRSA in MRSA-positive patients on admission. Of the 5,155 patients screened for MRSA on discharge, 2.9% (95% confidence interval [CI], 2.43-3.34) were found to be positive. In the subcohort screened on both admission and discharge (n = 2,724), 1.3% of all patients acquired MRSA while in hospital (incidence rate, 2.1/1,000 hospital bed-days in this cohort [95% CI, 1.5-2.9]), while 1.3% remained MRSA positive throughout hospital stay. Three risk factors for acquisition of MRSA were identified: age above 64 years, self-reported renal failure, and self-reported presence of open wounds. On a population level, the prevalence of MRSA colonization did not differ between admission and discharge. Cross-transmission of MRSA takes place in Scottish hospitals that have implemented universal screening for MRSA. This study reinforces the importance of infection prevention and control measures to prevent MRSA cross-transmission in hospitals; universal screening for MRSA on admission will in itself not be sufficient to reduce the number of MRSA colonizations and subsequent MRSA infections.

MRSA screening: can one swab be used for both culture and rapid testing? An evaluation of chromogenic culture and subsequent Hain GenoQuick PCR amplification/detection

BackgroundAs part of universal decolonization, intensive care unit (ICU) patients may receive intranasal mupirocin to reduce MRSA infections. However, due to concerns about widespread use of mupirocin promoting resistance, some have proposed a bactericidal antiseptic, povidone-iodine (P-I), as an alternative. There are few data as to whether either agent reduces the sensitivity of MRSA nares screening. This study aimed to discern whether intranasal P-I interferes with MRSA screening via polymerase chain reaction (PCR) and/or culture.MethodsWe performed a prospective proof-of-concept cohort study at our >1200-bed, community-based academic health care system, enrolling 20 patients who screened MRSA-positive by PCR on admission to a medical ICU, medical-surgical ICU, or medical stepdown unit. All patients received twice-daily intranasal P-I (7.5%) for 5 days or until unit discharge. We obtained follow-up nasal MRSA PCR tests after 4-6 days, and confirmed all PCR results with MRSA cultures using CHROMagar™. We calculated sensitivity of MRSA PCR at follow-up using culture as the gold standard.ResultsTwenty patients were enrolled, with a median age of 72 years (range, 53-91). Most (75%) were admitted with active infection, and 40% had known MRSA history. All baseline PCRs were confirmed by positive culture. Patients underwent a mean of 8.1 (range, 4-13) nasal P-I applications prior to follow-up testing. At follow up, 16/20 (80%) remained MRSA-positive via both PCR and culture. Of the 4 patients with negative follow-up results, 1 was both PCR-/culture-, 2 were PCR+/culture- and 1 was PCR-/culture+. All 4 had received ≥1 doses of vancomycin, and one person had received ≥1 doses of linezolid. The sensitivity of MRSA PCR at follow-up was 94%.ConclusionMRSA PCR remains highly sensitive even after multiple applications of P-I, and may be more sensitive than culture. If clinicians wish to screen for MRSA for stewardship or other purposes, receipt of nasal P-I should not be a deterrent. However, the fact that most patients remained culture-positive after 4-13 applications raises concerns that P-I is less effective than mupirocin for clearing nasal colonization. We recommend using quantitative cultures to further investigate the effectiveness of nasal P-I.DisclosuresAll Authors: No reported disclosures

Colonization of methicillin-resistant Staphylococcus aureus (MRSA) can be detected via nasal screens. Evidence indicates that negative MRSA nasal screens may be used to de-escalate anti-MRSA antibiotics in pulmonary infections. In the ICU, universal decolonization with intranasal mupirocin is implemented to reduce MRSA infection risk. This study aimed to determine whether mupirocin administration affects the reliability of MRSA PCR nasal screens. This retrospective study divided subjects based on timing of intranasal mupirocin administration-before and after MRSA screen. Subjects with confirmed pulmonary infection that received vancomycin, blood/respiratory cultures, and had MRSA PCR screen collected were included. Subjects with concurrent infection requiring vancomycin or MRSA infection in prior 30 days were excluded. Primary outcome of this non-inferiority study was the negative predictive value (NPV) of the screen. Secondary outcomes included the positive predictive value (PPV), sensitivity, and specificity of the screen and duration of vancomycin. Ultimately, 125 subjects were included in each group. The NPV in the group receiving mupirocin before screen was 95.2%, whereas the NPV in the group receiving mupirocin after screen was 99%. The difference between groups was -3.8% (90% CI -7.8%-0.2%; p=0.31), which failed to meet non-inferiority criteria. The secondary outcomes of PPV, sensitivity and specificity of the screen were similar in both groups. The duration of vancomycin was significantly longer in subjects receiving mupirocin before screen (3 days vs. 2 days; p<0.05). Intranasal mupirocin prior to the screen may reduce NPV in pulmonary infections. Approach de-escalation of vancomycin based on screen results with caution.

234. Does nasal screening for methicillin resistant Staphylococcus aureus (MRSA) prevent deep surgical site infections for elective cervical spinal fusion?

IntroductionIn the maternity population the benefits of MRSA (Methicillin-resistant Staphylococcus aureus) screening remain unproven. The authors report results of recently introduced screening in Southampton.MethodsWomen were screened if booked for elective...

Background: Methicillin-resistant Staphylococcus aureus (MRSA) is a frequent source of infection in the neonatal intensive care unit (NICU). Due to the serious consequences associated with MRSA infections in neonates, much effort has been made to prevent and control epidemics in NICUs. Since 2006, our hospital has performed MRSA nasal surveillance screening of all newborns in the NICU in accordance with the recommendations of the Chicago-Area Neonatal MRSA Working Group. In 2017, a MRSA infection was identified in a newborn shortly after transfer from an outside hospital and who had an initial negative MRSA admission screen. As a result, we modified the admission screening process for all transfers from outside NICUs. Methods: The Evanston Hospital Infant Special Care Unit is a level 3 NICU in the northern suburbs of Chicago with 44 NICU beds and 450 admissions per year. Effective July 1, 2017, all NICU transfers have a nasal MRSA screen performed upon admission and after 48 hours. The transferred baby is placed on contact isolation until both screening results return negative. Nasal MRSA testing is performed using both PCR on the BD MAX MRSA Assay platform and is confirmed by culture using MRSA CHROMagar TM. Results: Between July 1, 2017, and October 31, 2019, 112 neonates were transferred from outside NICUs. Moreover, 105 (94%) had at least 1 MRSA screen completed and 99 (88%) had both MRSA screens completed. Of 99 with 2 screens, only 1 neonate had an initial positive nasal MRSA screen. Of the remaining 98 negative babies, none had a repeat positive nasal MRSA screen within 48 hours of admission. of 99 neonates with 2 serial admission MRSA screens, 82 (83%) were transferred within 48 hours of birth. In addition, 17 neonates were transferred &gt;48 hours after birth, including the 1 MRSA-positive baby. Conclusions: In an attempt to identify all potential MRSA-positive neonates transferred to our NICU, we instituted a policy of 2 admission nares swabs. However, our data suggest that a single initial MRSA swab may be sufficient. If continued collection of a second screen is performed, it may be sufficient to screen babies who have been hospitalized for at least 48 hours prior to transfer, which eliminates 83% of admission testing and results in a cost savings.Funding: NoneDisclosures: None

Frequency-risk and duration-risk relations between occupational livestock contact and methicillin-resistant Staphylococcus aureus carriage among workers in Guangdong, China