Nasal Methicillin-resistant Staphylococcus Aureus Research Articles

Clinical Efficacy of Nasal Screening and Methicillin-Resistant Staphylococcusaureus Decolonization in Total Hip Arthroplasty without Chlorhexidine Soap or Vancomycin.

Nasal colonization with methicillin-resistant Staphylococcus aureus (MRSA) is a known risk factor for periprosthetic joint infection (PJI). In our facility, preoperative prophylaxis with mupirocin without the chlorhexidine soap scrub or vancomycin was consistently implemented for more than 15years. This study aimed to evaluate the current screening and treatment of intranasal MRSA colonization in our elective primary THA patient population. All patients who underwent primary THA between April 2011, and March 2021 were included in this analysis. All patients were screened preoperatively for nasal MRSA approximately 1month before surgery. Patients with nasal MRSA contamination are treated with topical mupirocin to eradicate the bacteria before surgery. The patients were examined again approximately two weeks before surgery. We evaluated the current screening and treatment of intranasal colonization with MRSA in our elective primary total hip arthroplasty (THA) patient population. Out of 6251 patients, 106 (1.7%) had nasal MRSA contamination. The bacteria were not eradicated in three (3.6%) patients at the second screening. Twenty-two joints (0.35%) out of the 6251 had deep infections. Only 1 patient out of the 106 MRSA nasal carriers suffered from PJI. Twenty-one of the 6145 non-carriers had PJI. The difference between the prevalence of nasal MRSA contamination and the incidence of deep infections was not statistically significant. Our findings suggest that screening of all patients for nasal MRSA before THA followed by mupirocin calcium treatment if needed is sufficient PJI prophylaxis.

Investigating the relationship between muscle mass and nasal Methicillin-Resistant Staphylococcus aureus (MRSA) colonization: Analysis of the National Health and Nutrition Examination Survey (NHANES).

Methicillin-resistant Staphylococcus aureus (MRSA) nasal colonization is associated with an increased risk of infection disease. Low muscle mass has been linked to higher levels of inflammatory markers and weakened immune response, which may impact the susceptibility to nasal MRSA colonization. The relationship between muscle function and immune response to pathogens may be bidirectional. This study investigates the association between muscle mass and nasal MRSA colonization in adults. The present cross-sectional study utilized data from the National Health and Nutrition Examination Survey (NHANES) conducted between 2001 and 2004. Appendicular skeletal muscle mass (ASM) adjusted by body mass index (BMI) (ASM/BMI) was used to evaluate muscle mass. Multivariate logistic regression, adjusted for demographic and infection factors, was used to analyze the association between muscle mass and nasal colonization by MRSA. A subgroup analysis based on age and gender was performed to assess the impact of muscle mass on nasal MRSA colonization. Nasal MRSA colonization was more prevalent in females, those with smaller household sizes, lower income, lower ASM/BMI, those who had stayed in healthcare facilities in the past 12 months, and individuals with diabetes and smoking habits. After adjusting for confounding factors, a dose-dependent association was found between decreasing quartiles of ASM/BMI and the risk of nasal MRSA colonization (p < 0.05). Additionally, per 1 unit increase in ASM/BMI was related to a 64% lower risk of nasal MRSA colonization. This study suggests a significant negative correlation between ASM/BMI and the risk of nasal MRSA colonization. However, more prospective studies are required to investigate the causal relationship between muscle mass and colonization.

Nasal Methicillin-Resistant Staphylococcus aureus Culture Screens in the Setting of Universal Decolonization

Introduction The negative predictive value (NPV) of nasal methicillin-resistant Staphylococcus aureus (MRSA) screens has been compromised by universal decolonization practices. We aimed to determine the reliability of the nasal MRSA culture screen to deescalate antibiotic therapy in the setting of decolonization with ethyl alcohol. Methodology A retrospective observational cohort study was conducted using 62% ethanol solution intranasally per protocol. Patients were divided into 2 groups based on whether they received decolonization. Data were analyzed to determine NPV of the nasal MRSA culture screen with and without decolonization. Results A total of 505 cases were screened, and 128 subjects were included. One hundred two received decolonization, whereas 26 did not. Baseline characteristics were well balanced. Overall MRSA infection prevalence was 31.25%. The NPV was 73% in the decolonized group compared with 80% in the group without. Positive predictive value was 63% in the group receiving decolonization compared with 100% in the group without. There was also a higher specificity but lower sensitivity of the nasal MRSA culture screen in the decolonization group. Nine patients in the decolonization group required reescalation of antibiotics compared with nil in the other group. Conclusions Culture-based nasal MRSA screens are less accurate than PCR tests, as ethyl alcohol leads to false-negative results. A lower NPV in the decolonization group predisposes to increased false negative results, leading to inappropriate antibiotic deescalation and often requiring reinitiation. Nasal MRSA culture screen is less reliable if alcohol has already been administered for decolonization and cannot be used as an appropriate tool to guide antibiotic deescalation.

Association between methicillin-resistant Staphylococcus aureus nasal carriage and infection after pancreatic surgery.

Methicillin-resistant Staphylococcus aureus (MRSA) infections after pancreatectomy are relatively rare; however, they can be fatal when associated with pseudoaneurysms. For the past 12 years, we have been investigating nasal MRSA carriage by polymerase chain reaction testing, postoperatively in patients admitted to the intensive care units, to prevent nosocomial infections. Here, we investigated the relationship between MRSA nasal carriage and postoperative MRSA infection at the surgical site, following pancreatectomy. This single-center retrospective study analyzed 313 pancreatectomies (220 pancreaticoduodenectomies and 93 distal pancreatectomies), performed at our hospital between January 2011 and June 2022. The incidence of surgical site infection (SSI) and postoperative MRSA infection were compared between the nasal MRSA-positive and nasal MRSA-negative groups. MRSA nasal carriage was identified in 24 cases (7.6%), and the frequency of SSIs in the nasal MRSA-positive and MRSA-negative groups were 50% and 36.7%, respectively, with no significant difference (p = .273). However, the frequency of MRSA infection among the SSI cases was significantly higher in the nasal MRSA-positive group (16.7%) than in the nasal MRSA-negative group (1.7%) (p = .003). It should be noted that MRSA carriers have a significantly higher frequency of MRSA-positive SSIs.

Pilot study on nasal microbiota dynamics and MRSA carriage of a pig cohort housed on straw bedding.

Methicillin-resistant Staphylococcus aureus (MRSA) can be transmitted between pigs and humans on farms. Hence, the reduction of MRSA carriage in pigs could decrease the risk of zoonotic transmission. Recently, straw bedding has been found to significantly reduce MRSA carriage in pigs. The mechanisms behind this effect remain unclear but changes in the nasal microbiome may play a role. In this exploratory study, the nasal microbiota of pigs kept on straw was examined using V1/V2 16S rRNA gene sequencing. Nasal swabs were collected from 13 pigs at six different time points during the course of a full fattening cycle resulting in 74 porcine samples. In addition, straw samples were collected at each time point. Eleven out of 13 pigs were MRSA positive at housing-in. We found a strong temporal pattern in the microbial communities. Both microbial diversity and abundance of Staphylococcus species peaked in week 5 after introduction to the straw stable decreased in week 10, when all pigs turned MRSA-negative, and increased again toward the end of the fattening period. These findings show that the introduction of pigs into a new environment has a huge impact on their nasal microbiota, which might lead to unfavorable conditions for MRSA. Moreover, other Staphylococcus species may play a role in eliminating MRSA carriage. We designed a follow-up study including two different husbandry systems to further assess these effects.

Hiding in Plain Sight: Benefit of Abrasion and Laceration Swabs in Identification of Panton-Valentine Leucocidin (PVL)-Meticillin Resistant Staphylococcus aureus (MRSA) Colonisation in Military Personnel.

Background Outbreaks of Panton-Valentine Leucocidin (PVL)-producing methicillin-resistantStaphylococcus aureus(MRSA) skin and soft tissue infections (SSTIs) are a recurrent challenge for the Royal Marines at the Commando Training Centre (CTCRM). The intensity of commando training, its impact on skin integrity, and persistent colonisation reservoirs within the training centre have thwarted attempts to prevent these outbreaks. Aim To present an outbreak of PVL-producing MRSA SSTIs at a military training centre, demonstrating the benefit of additional abrasion and laceration swabs on the identification of colonised personnel and showing the effectiveness of a 10-day decolonisation regime. Method Following the identification of the outbreak of PVL-producing MRSA, all 36 members of the Recruit Troop underwent nasal MRSA screening to identify MRSA carriers. The screening was repeated on day 16 after completing an enhanced 10-day decolonisation regime. A third screening was conducted on the 110th day after a second peak of infection was identified. Various infection control measures, such as enhanced cleaning, restriction of movement and adjustments to the military training serials, were introduced to prevent further spread through the training centre. Results In this outbreak, two-thirds (eighteen) of the Recruit Troop suffered MRSA-PVL skin infections requiring antibiotic therapy and three required hospital admission for surgical management of their abscesses. The outbreak lasted 130 days, with two spikes in infections 10 weeks apart. The outbreak was successfully confined to one troop. Conclusion With concerns about low identification rates of carriers using nasal screening for MRSA, in this outbreak, we improved the identification of asymptomatic carriage with the simple step of additional culture swabs for all cuts and abrasions. Improved identification of colonised recruits, along with an enhanced decolonisation regime and rigid infection control practices, prevented the further spread of the clone through the training centre. In a population with constant ongoing skin trauma, such as the military, contact sport athletes and iIV drug users, our results show that a culture of suitable abrasions/lacerations will improve the identification of MRSA colonisation compared with nasal swabs alone. Despite ongoing skin trauma and the logistical difficulties in delivering effective decolonisation during military training, decolonisation was successful in 79% of recruits after one decolonisation and 87% after the second 10-day decolonisation.

Effects of Discontinuation of Weekly Surveillance Testing on Methicillin-Resistant Staphylococcus aureus in the NICU.

Methicillin-resistant Staphylococcus aureus (MRSA) infection is a major cause of serious morbidity and mortality in the neonatal intensive care unit (NICU). There is no clear consensus on infection control measures. Some approaches to MRSA colonization management may be burdensome with unclear benefits. The objective of this study was to determine if stopping weekly MRSA surveillance with active detection and contact isolation (ADI) was associated with a change in infection rate. This is a retrospective cohort study of infants admitted to two affiliated NICUs. The ADI cohort infants received weekly nasal MRSA cultures and were placed in contact isolation if MRSA colonized for the duration of their hospitalization. The No Surveillance cohort infants were only placed in isolation if there was active MRSA infection or if MRSA colonization was identified incidentally. The rates of infection were determined between the cohorts. There were 8,406 neonates representing 193,684 NICU days in the comparison period. In the ADI cohort, MRSA colonization occurred in 3.4% of infants and infection occurred in 29 infants (0.4%). There were no differences between cohorts in the percent of infants with a MRSA infection at any site (0.5 vs. 0.5%, p = 0.89), rate of MRSA infections per 1,000 patient-days (0.197 vs. 0.201, p = 0.92), rate of bloodstream infections (0.12 vs. 0.26%, p = 0.18), or in the overall mortality rate (3.7 vs. 3.0% p = 0.13). ADI represented an annual cost of $590,000. The rates of MRSA infection did not change when weekly ADI was discontinued and was associated with a decrease in cost and resource utilization. · Placing MRSA-colonized infants in contact isolation is a common practice.. · Data are limited with respect to efficacy in the NICU.. · This study provides evidence that active detection and contact isolation for MRSA colonization may not be beneficial..

Identification of Risk Factors for Nasal Colonization of Methicillin-resistant Staphylococcus aureus and Vancomycin-resistant Staphylococcus aureus in Health Workers at a Tertiary Hospital, Indonesia

BACKGROUND: Methicillin-resistant Staphylococcus aureus (MRSA) and Vancomycin-resistant S. aureus (VRSA) frequently cause nosocomial infections yearly. During the COVID-19 pandemic, the potential for excessive use of antibiotics is a global threat to the increasing incidence of multiresistant bacteria. AIM: This study aimed to determine MRSA and VRSA colonization and identify factors associated with the risk of MRSA and VRSA nasal colonization in health workers at Dr. Soemarno Sosroatmodjo General Hospital, Kuala Kapuas, as one of the type C hospitals in Indonesia. METHODS: This cross-sectional analytic study at Dr. Soemarno Sosroatmodjo General Hospital, a tertiary hospital in Indonesia. A 128 health workers’ subjects had undergone nasal swab screening for MRSA and VRSA colonization examinations. Then, they were asked to complete a questionnaire concerning the risk factors of MRSA and VRSA infections. RESULTS: Nasal swab results obtained as many as 30 (23.5%) MRSA positive subjects and 6 (4.7%) subjects with positive VRSA. The most common risk factors that led to MRSA colonization included a history of positive MRSA in the previous hospital (60%), a history of ear, nose, and throat infection (41.7%), and did not do hand rub/handwash (36.7%). In comparison, the most risk factors for VRSA colonization were having pigs farm at home (33.3%), a history of positive MRSA in the previous hospital (20%), and a history of hospitalization in the past 6–12 months (16.7%). The results of multivariate analysis showed the most powerful and statistically significant risk factors in influencing nasal MRSA colonization were a history of positive MRSA in the previous hospital (OR 13.69, 95% confidence intervals [CI]: 1.34–140.25, p = 0.028) and did not do hand rub/handwash (OR 2.95, 95% CI: 1.167–7.49, p = 0.023). Meanwhile, marital status (OR 0.160, 95% CI: 0.02–1.06), p = 0.058) and home care service (OR 6.10, 95% CI: 0.79–46.96, p = 0.082) were the strongest risk factors for nasal colonization of VRSA but not statistically significant. CONCLUSION: As many as, 23.5% and 4.7% of healthcare workers’ subjects were found with nasal colonization of MRSA and VRSA, respectively. Accordingly, strict policies are needed to minimize the transmission of these organisms from the hospital setting to the community.

Positivity of repeat nasal MRSA PCR screening: a single-center experience.

Repeating nasal methicillin-resistant Staphylococcus aureus (MRSA) polymerase chain reactions (PCRs) within 14 days may increase healthcare costs and inform anti-MRSA antibiotic therapy without known benefit. Within an inpatient admission, our retrospective, single-center evaluation found that conversion from negative to positive on repeat nasal MRSA PCR screen was uncommon (2%).

204. Genomic comparison of blood and colonizing nasal isolates in patients hospitalized with methicillin-resistant Staphylococcus aureus (MRSA) bacteremia

Abstract Background Methicillin-resistant Staphylococcus aureus (MRSA) is a common cause of health-care associated infections, particularly bloodstream infections (BSI). Concomitant colonization of the anterior nares has been shown to have implications on persistence, recurrence, and transmission events. We performed genomic comparisons between paired nasal and blood MRSA isolates obtained from the same patient to elucidate the genetic differences that may contribute to within-host invasion and virulence. Methods Patients hospitalized with MRSA bloodstream infection were swabbed in the bilateral nares. Paired blood and nasal isolates underwent DNA extraction and spa typing. Nasal and blood isolates from the same patients with matching spa types were sequenced by Illumina and PacBio respectively. For genomic analysis, PathoSPOT and Snippy were used to compare genomes of nasal and blood isolate pairs to evaluate single nucleotide polymorphisms, insertions and deletions. Results Of 121 patients with MRSA BSI, 87 patients (72%) had concomitant colonization of the anterior nares with MRSA. Spa type of t002 predominated in both blood and nasal isolates. From the 76 pairs that underwent genomic analysis, several mutated genes were identified across all pairwise comparisons, 8 of which recurred in more than one patient pair. These included genes involved in conferring antibiotic resistance, increased mutability, immune evasion, and adaptive metabolism. Conclusion In patients with MRSA BSI and concomitant MRSA nasal colonization, mutations identified by genomic analysis in blood-nasal pairs are implicated in contributing to invasion and within-host adaptability. Disclosures All Authors: No reported disclosures.

1804. Quality Improvement Project to improve empiric antibiotic therapy for skin and soft tissue infections using the nasal MRSA PCR

Abstract Background Large cohort studies from the Veteran’s Administration support the negative predictive value of the methicillin resistant Staphylococcus aureus (MRSA) nasal polymerase chain reaction (PCR) swabs for skin and soft tissue infection (SSTI). We investigated the use of the nasal MRSA PCR swab to reduce the inappropriate empiric use of vancomycin and piperacillin-tazobactam for SSTI at our institution. Methods Between July and August 2021, we educated Hospital Internal Medicine (HIM) and Internal Medicine Residents (IMR) on the basics of SSTI management and the utility of a negative nasal MRSA PCR swab. Data on empiric use of vancomycin and piperacillin-tazobactam for SSTIs were collected 3/1/2021 to 7/1/2021 (pre-intervention) and 8/30/2021 to 12/29/2021 (post-intervention). We excluded patients who didn’t have an SSTI, weren’t managed by IMR or HIM, and whose empiric antibiotics were for another indication. To account for antibiotics started in the emergency department (ED), a patient was regarded as having received appropriate empiric antibiotics if they were de-escalated in the first 24 hours of being admitted to IMR or HIM. Example of education material. These fliers were distributed to resident rooms following a series of noon conferences Results Pre-intervention there were 106 patient encounters. In 56 of these (52.8%), patients were placed on inappropriate empiric antibiotics. Post-intervention, there were 72 patient encounters. In 23of these (31.9%), patients were placed on inappropriate empiric antibiotic for an absolute risk reduction (ARR) of 20.9% with a statistically significant 95% CI (6.522 - 35.249) and a number needed to treat (NNT) of 4.78. Nasal MRSA PCR testing increased from 40.6% to 56.9%. The ARR among the HIM teams was 21.3% and was statistically significant with a 95% CI (4.24 - 38.394). Their proportion of MRSA testing increased from 41.5% to 50%. The IMR teams had an ARR of 14.8%, which was not statistically significant (95% CI, -11.339 to 40.884). Their MRSA nasal PCR testing increased from 37.5% to 72%. Conclusion Education on SSTI treatment coupled with use of the MRSA nares PCR appeared to improve empiric antibiotic choices. Residents stated that the nasal MRSA PCR facilitated empiric antibiotic choice. Positive ARR was seen in whole and sub-group analyses of physician teams. We theorize that the lack of statistical significance in the IMR group was related to a small sample size. Disclosures All Authors: No reported disclosures.

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

<h3>BACKGROUND CONTEXT</h3> Preoperative MRSA screening and decolonization has demonstrated success for some orthopaedic subspecialties in prevention of surgical site infections (SSIs). Spine surgery, however, has seen varied results, potentially secondary to the anatomic and surgical heterogeneity of the patients included in prior studies. Given that prior research has demonstrated greater propensity for gram positive SSIs in the cervical spine, we sought to investigate if MRSA screening would be more impactful in the cervical spine. <h3>PURPOSE</h3> The purpose of this study was to determine the relationship between nasal MRSA testing and SSI rates specifically in the setting of primary posterior cervical instrumented spine surgery. <h3>STUDY DESIGN/SETTING</h3> Retrospective cohort study. <h3>PATIENT SAMPLE</h3> Adult patients undergoing primary instrumented posterior cervical procedures from January 2015-December 2019 at two tertiary academic referral centers in an urban setting <h3>OUTCOME MEASURES</h3> Physiologic measures: subfascial presumed infected collection or abscess within 90 days of the index operation. <h3>METHODS</h3> Adult patients undergoing primary instrumented posterior cervical procedures from January 2015-December 2019 were reviewed for MRSA testing < 90-days before surgery, preoperative mupirocin, perioperative antibiotics and SSI defined as operative incision and drainage (I&D) < 90-days after surgery. Trauma, tumor and infection cases were excluded. Logistic regression modeling was used with SSI the primary outcome and MRSA screening the primary predictor with clinical and demographic factors as covariates. <h3>RESULTS</h3> This study included 668 patients, of whom MRSA testing was performed in 212 patients (31.7%) and 6 (2.8%) were colonized with MRSA. Twelve patients (1.8%) underwent an I&D. On adjusted analysis, preoperative MRSA testing was not associated with postoperative I&D risk. Perioperative vancomycin similarly had no association with postoperative I&D risk. Notably, six patients (50%) grew MSSA from intraoperative cultures, with no cases of MRSA. <h3>CONCLUSIONS</h3> There was no association between preoperative nasal MRSA screening and SSIs in primary posterior cervical instrumented procedures, nor was there any association between vancomycin or infection rate. Furthermore, there was a preponderance of gram-positive infections but none caused by MRSA. Given these findings, the considerable cost and effort associated with MRSA testing in the setting of primary posterior cervical instrumentation may not be justified. Further research should investigate if higher-risk scenarios demonstrate greater utility of preoperative testing. <h3>FDA DEVICE/DRUG STATUS</h3> This abstract does not discuss or include any applicable devices or drugs.

Does Nasal Screening for Methicillin-Resistant Staphylococcus aureus (MRSA) Prevent Deep Surgical Site Infections for Elective Cervical Spinal Fusion?

Retrospective cohort study. The objective of this study was to determine the relationship between nasal methicillin-resistant Staphylococcus aureus (MRSA) testing and surgical site infection (SSI) rates in the setting of primary posterior cervical instrumented spine surgery. Preoperative MRSA screening and decolonization has demonstrated success for some orthopedic subspecialties in prevention of SSIs. Spine surgery, however, has seen varied results, potentially secondary to the anatomic and surgical heterogeneity of the patients included in prior studies. Given that prior research has demonstrated greater propensity for gram positive SSIs in the cervical spine, we sought to investigate if MRSA screening would be more impactful in the cervical spine. Adult patients undergoing primary instrumented posterior cervical procedures from January 2015 to December 2019 were reviewed for MRSA testing <90 days before surgery, preoperative mupirocin, perioperative antibiotics, and SSI defined as operative incision and drainage (I&D) <90 days after surgery. Logistic regression modeling used SSI as the primary outcome, MRSA screening as primary predictor, and clinical and demographic factors as covariates. This study included 668 patients, of whom MRSA testing was performed in 212 patients (31.7%) and 6 (2.8%) were colonized with MRSA. Twelve patients (1.8%) underwent an I&D. On adjusted analysis, preoperative MRSA testing was not associated with postoperative I&D risk. Perioperative vancomycin similarly had no association with postoperative I&D risk. Notably, 6 patients (50%) grew methicillin sensitive Staphylococcus aureus from intraoperative cultures, with no cases of MRSA. There was no association between preoperative nasal MRSA screening and SSIs in primary posterior cervical instrumented procedures, nor was there any association between vancomycin or infection rate. Furthermore, there was a preponderance of gram positive infections but none caused by MRSA. Given these findings, the considerable cost and effort associated with MRSA testing in the setting of primary posterior cervical instrumentation may not be justified. Further research should investigate if higher-risk scenarios demonstrate greater utility of preoperative testing.

Methicillin-resistant staphylococci among school children in Mariental, Namibia

Methicillin-resistant Staphylococcus aureus (MRSA) is resistant to beta-lactam antibiotics, while some strains are multi-drug resistant and may produce disease-causing toxins. Drug resistant strains are often responsible for chronic, persistent and recurrent infections, which pose a challenge for healthcare practitioners. Our study aimed to determine the prevalence of nasal MRSA and methicillin-resistant coagulase-negative staphylococci (MRCoNS) among school children in the Mariental community, southern Namibia. This was a cross-sectional study in the Mariental District. Nasal specimens (swabs) were collected from 272 randomly selected learners aged 6–14 years attending school in the area during the months of March, September and October 2016. Isolation and identification of staphylococci were performed using standard microbiological methods. Methicillin-resistant isolates were identified by their resistance towards cefoxitin (30 µg) using the Kirby-Bauer disk diffusion assay. Enterotoxin production among multi-drug resistant MRSA isolates was detected with a SET-RPLA toxin detection kit. Methicillin-resistant S. aureus was isolated from 48 (17.6%) learners and MRCoNS from only seven (2.6%). Methicillin-resistant S. aureus colonization was significantly higher (P = 0.003) in the age group 11–14 years than in the group 6–10 years. Among the 433 staphylococcal isolates screened for cefoxitin resistance, 51 (11.8%) were MRSA and seven (1.6%) were MRCoNS. From the 51 MRSA isolates, 22 (43.1%) were multi-drug resistant of which six were enterotoxigenic. This is the first report on MRSA and MRCoNS among school children in Namibia. The presence of multi-drug resistant and potentially virulent staphylococci among school children in Mariental, Namibia, is of concern. Self-infection by these bacteria poses various health risks for the children. It is recommended that school health programmes improve current hygiene practices. Frequent handwashing can prevent staphylococcal disease and spread of resistant strains among learners and the wider community.

1138. Utility of Methicillin-resistant Staphylococcus aureus Nares Screening in Hospitalized Children With Acute Infectious Disease Syndromes

BackgroundEmpirical antibiotic regimens frequently include treatment for methicillin-resistant Staphylococcus aureus (MRSA). Studies in adults with pneumonia support the use of a negative MRSA nares screening (MNS) to help de-escalate antibiotic therapy. Comparable pediatric data in the literature is scarce. We aimed to evaluate the use of MNS for antibiotic de-escalation in hospitalized children (< 18 years) at a tertiary children’s hospital. MethodsA retrospective chart review was conducted of pediatric inpatients (January 01, 2015 to December 31, 2020) with a presumed infectious diagnosis who had a PCR-based MNS test and a clinical culture (i.e. site of infection or blood) performed as part of their diagnostic work up. Those who were screened >5 days since admission or > 48 hours since start of MRSA-active antimicrobials, and those who had antibiotic treatment withdrawn after 48 hours because of negative cultures were excluded. ResultsA total of 101 children were included with a median age (range) of 2 years (0-17) and about half (n=57, 56.4%) were male. Top three diagnosis groups were skin and soft tissue infections (n=33, 32.7%), toxin-mediated syndromes (n=21, 20.8%), and osteoarticular infections (n=13, 12.9%). Pneumonia accounted for only six (5.9%) patients. The prevalence of nasal MRSA colonization was 6.9% (n=7). The sensitivity of the MNS test to predict a MRSA infection was 42.9% with a specificity of 95.7%. The positive predictive value (PPV) and negative predictive values (NPV) were 42.9% and 95.7%, respectively. In about half (55/95, 57.9%) of patients initiated on anti-MRSA therapy, these agents were discontinued during the admission. A quarter (n=14, 25.5%) were de-escalated based on the negative MNS test alone, and another third (n=21, 38.2%) after negative MNS test and negative culture results became available. ConclusionPediatric providers at this institution have started to use the MNS to help limit anti-MRSA therapy. We noted a high NPV which suggests that MNS may be useful for timely de-escalation of anti-MRSA therapy and thereby a useful antimicrobial stewardship tool for hospitalized children. Prospective studies to evaluate the utility of MNS for the various infectious syndromes are warranted.Disclosures All Authors: No reported disclosures

Utility of Methicillin-Resistant Staphylococcus aureus Nares Screening in Hospitalized Children with Acute Infectious Disease Syndromes.

Studies in adults support the use of a negative methicillin-resistant Staphylococcus aureus (MRSA) nares screening (MNS) to help limit empiric anti-MRSA antibiotic therapy. We aimed to evaluate the use of MNS for anti-MRSA antibiotic de-escalation in hospitalized children (<18 years). Records of patients admitted between 1 January 2015 and 31 December 2020 with a presumed infectious diagnosis who were started on anti-MRSA antibiotics, had a PCR-based MNS, and a clinical culture performed were retrospectively reviewed. A total of 95 children were included with a median age (range) of 2 (0–17) years. The top three diagnosis groups were skin and soft tissue infections (n = 38, 40%), toxin-mediated syndromes (n = 17, 17.9%), and osteoarticular infections (n = 14, 14.7%). Nasal MRSA colonization and growth of MRSA in clinical cultures was found in seven patients (7.4%) each. The specificity and the negative predictive value (NPV) of the MNS to predict a clinical MRSA infection were both 95.5%. About half (n = 55, 57.9%) had anti-MRSA antibiotics discontinued in-house. A quarter (n = 14, 25.5%) were de-escalated based on the negative MNS test alone, and another third (n = 21, 38.2%) after negative MNS test and negative culture results became available. A high NPV suggests that MNS may be useful for limiting unnecessary anti-MRSA therapy and thereby a useful antimicrobial stewardship tool for hospitalized children. Prospective studies are needed to further characterize the utility of MNS for specific infectious diagnoses.

Epidemiology of Methicillin-Resistant Staphylococcus Aureus in Arab Countries of the Middle East and North African (MENA) Region.

Available data suggest a high burden of methicillin-resistant staphylococcus aureus (MRSA) in Arab countries of the Middle East and North Africa (MENA). To review the MRSA rates and molecular epidemiology in this region, we used PubMed search engine to identify relative articles published from January 2005 to December 2019. Great heterogeneity in reported rates was expectedly seen. Nasal MRSA colonization ranged from 2%–16% in Gulf Cooperation Council (GCC), 1–9% in the Levant, and 0.2%–9% in North African Arab states. Infective MRSA rates ranged from 9%–38% in GCC, 28%–67% in the Levant, and 28%–57% in North African states. Studies demonstrated a wide clonal diversity in the MENA. The most common molecular types belonged to 5 clonal complexes (CC) known to spread worldwide: CC5, CC8, CC22, CC30, and CC80. The most prevalent strains had genotypes related to the European community-acquired MRSA (CA-MRSA), Brazilian/Hungarian hospital-acquired MRSA (HA-MRSA), UK-EMRSA-15 HA-MRSA, and USA300 CA-MRSA. Finally, significant antimicrobial resistance was seen in the region with variation in patterns depending on location and clonal type. For a more accurate assessment of MRSA epidemiology and burden, the Arab countries need to implement national surveillance systems.

Nasal Carriage of Methicillin-Resistant Staphylococcus aureus among Healthcare Workers in a Tertiary Care Hospital, Kathmandu, Nepal.

Introduction Methicillin-resistant Staphylococcus aureus (MRSA) is one of the most common causes of nosocomial infections. One of the potential risk factors for nosocomial staphylococcal infections is colonization of the anterior nares of healthcare workers (HCWs). Our study aimed to determine the rate of nasal carriage MRSA among HCWs at Manmohan Memorial Medical College and Teaching Hospital, Kathmandu. Methods Two hundred and thirty-two nasal swabs were collected from HCWs of Manmohan Memorial Medical College and Teaching Hospital, Kathmandu, Nepal, within six months (February 2018–July 2018). Nasal swabs were cultured, and S. aureus isolates were subjected to the antimicrobial susceptibility test by the modified Kirby–Bauer disc diffusion method. MRSA and iMLSB (inducible macrolide lincosamide streptogramin B) resistance was screened using the cefoxitin disc (30 μg) and D-test (clindamycin and erythromycin sensitivity pattern), respectively, following CLSI (Clinical and Laboratory Standard Institute) guidelines. Risk factors for MRSA colonization were determined using the chi-square test considering the p value ˂0.05 as significant. Results A total of 34/232 (14.7%) S. aureus were isolated, out of which 12 (35.3%) were MRSA. The overall rate of nasal carriage MRSA among HCWs was 5.2% (12/232). Colonization of MRSA was higher in males (8.7%) than in females (4.3%). MRSA colonization was found to be at peak among the doctors (11.4%). HCWs of the postoperative ward were colonized highest (18.2%). All MRSA isolates were sensitive to linezolid and tetracycline. iMLSB resistance was shown by 7(20.6%) of the isolates. MRSA strains showed higher iMLSB resistance accounting for 33.3% (4/12) in comparison to methicillin-susceptible strains with 13.6% (3/22). Smoking was found to be significantly associated with MRSA colonization (p=0.004). Conclusion Rate of nasal carriage MRSA is high among HCWs and hence needs special attention to prevent HCW-associated infections that may result due to nasal colonization.

9. The impact of nasal screening for methicillin-resistant staphylococcus aureus on surgical site infection after primary lumbar fusion

<h3>BACKGROUND CONTEXT</h3> Surgical site infections (SSI) constitute significant morbidity in spine surgery. Efforts at SSI prevention include preoperative methicillin-resistant Staphylococcus aureus (MRSA) screening and decolonization, with demonstrated success for arthroplasty patients along with vascular and cardiothoracic surgical patients. The variety of surgical approaches and anatomic regions within spine surgery can limit the impact of analyses at the subspecialty level. Despite the success of MRSA nasal screening and decolonization in reducing SSI rates in other disciplines, the impact on spine surgery is less understood. <h3>PURPOSE</h3> To determine the relationship between nasal MRSA testing and operative debridement rates for surgical site infection after primary lumbar fusion. <h3>STUDY DESIGN/SETTING</h3> Retrospective cohort study at two academic tertiary referral centers. <h3>PATIENT SAMPLE</h3> Adult patients (>18 years) were identified from January 2015 to March 2020 based on CPT codes for spinal instrumentation and fusion. Inclusion criteria were primary instrumented posterior lumbar fusion between 1-3 levels and exclusion criteria were revision surgery, tumor, infection, lateral-only surgery or operative surgeon with fewer than 20 cases. <h3>OUTCOME MEASURES</h3> Operative incision and drainage (I&D) of the index lumbar spine wound within 90-days after surgery was the primary outcome. <h3>METHODS</h3> Chart text, operative reports and laboratory reports were reviewed for data abstraction. Multivariable logistic regression modeling assessed for demographic differences between MRSA testing groups as well as factors contributing to I&D risk. <h3>RESULTS</h3> There were 2,148 patients included with a mean age 62.5 (SD 12.9), 56.9% female, and mean BMI 29.4 (SD 6.2). MRSA testing 90 days prior to surgery was completed in 884 (41.1%) of patients, and 19 (2.2%) of tested patients were colonized with MRSA preoperatively. Thirty-six (1.7%) patients underwent surgical I&D within 90 days of their index procedure for a surgical site infection. I&D risk was not associated with presence or result of MRSA testing, preoperative mupirocin prescriptions, or type of intraoperative antibiotic after controlling for surgeon. I&D risk was associated with higher BMI (5.7% increased risk for every 1 unit increase in BMI or a coefficient of 0.057, 95% confidence interval 0.017 to 0.097, p = 0.005) after controlling for age, diabetes and smoking status. <h3>CONCLUSIONS</h3> The present study demonstrates no difference in surgical I&D rates between patients who underwent MRSA testing, who had positive MRSA colonization or who underwent other interventions aimed at decreasing SSI rates such as preoperative mupirocin decolonization or addition of intraoperative vancomycin. Increased BMI was associated with risk of undergoing an operative I&D for surgical site infection, suggesting that patient factors dominate over clinical interventions in the prevention of surgical site infection after primary lumbar spine fusion. <h3>FDA DEVICE/DRUG STATUS</h3> This abstract does not discuss or include any applicable devices or drugs.

Nasal screening for methicillin-resistant Staphylococcus aureus does not reduce surgical site infection after primary lumbar fusion

BACKGROUND CONTEXTPreoperative methicillin-resistant Staphylococcus aureus (MRSA) testing and decolonization has demonstrated success for arthroplasty patients in surgical site infections (SSIs) prevention. Spine surgery, however, has seen varied results. PURPOSEThe purpose of this study was to determine the impact of nasal MRSA testing and operative debridement rates on surgical site infection after primary lumbar fusion. STUDY DESIGN/SETTINGRetrospective cohort study and/or Consolidated medical enterprise PATIENT SAMPLEAdult patients undergoing primary instrumented lumbar fusions from January 2015 to December 2019 were reviewed. OUTCOME MEASURESThe primary outcome was incision and drainage performed in the operating room within 90 days of surgery. METHODSMRSA testing <90-day’s before surgery, mupirocin prescription <30-day’s before surgery, perioperative antibiotics, and Elixhauser comorbidity index were collected for each subject. Bivariate analysis used Wilcoxon rank-sum testing and logistic regression modeling Multivariable logistic regression modeling assessed for associations with MRSA testing, intravenous vancomycin use, and I&D rate. RESULTSThe study included 1,884 patients for analysis, with mean age of 63.1 (SE 0.3) and BMI 29.5 (SE 0.1). MRSA testing was performed in 755 patients (40.1%) and was more likely to be performed in patients with lower Elixhauser index scores (OR 0.98, 95% CI 0.96–0.99, p=.021) on multivariable analysis. Vancomycin use increased significantly over time (OR 1.49 and/or year, 95% CI 1.3–1.8, p<.001) despite no change in mupirocin or I&D rates. MRSA testing, mupirocin prescriptions, perioperative parenteral vancomycin use, and intrawound vancomycin powder use had no impact on I&D rates. I&D risk was associated with higher BMI (OR 1.06, 95% CI 1.02–1.12, p=.009) and higher number of blood product units transfused (OR 1.23, 95% CI 1.03–1.46, p=.022). CONCLUSIONSThe present study demonstrates no impact on surgical I&D rates from the use of preoperative MRSA testing. Increased BMI and transfusions were associated with operative I&D rates for surgical site infection. As a result of the hospital directive, vancomycin use increased over time with no associated change in infection rates, underscoring the need for focused interventions, and engagement with antibiotic stewardship programs.