Methicillin-resistant Staphylococcus Aureus Cases Research Articles

Increasing trend of antimicrobial resistance among methicillin-resistant Staphylococcus aureus strains in Southwest Finland, 2007–2016: An analysis of shifting strain dynamics and emerging risk factors

ObjectivesSubstantial rise in the annual incidence of methicillin-resistant Staphylococcus aureus (MRSA) was reported in Southwest Finland (12.4 to 24.9/100 000 people) between 2007–2016. To understand the implications of these changes to the management of MRSA, we sought to analyze the antimicrobial resistance (AMR) trends of MRSA in relation with patient characteristics. MethodsAntimicrobial susceptibility was determined for ten clinically relevant antimicrobials. Strains with resistance to ≥2 antimicrobials were defined multi-resistant. The isolates were spa typed and clustered. AMR trends and risk factors were identified by associating resistant phenotypes with patient demographics. ResultsA total of 983 new MRSA cases were identified between 2007–2016. After 2011, significant increasing trends were observed in the proportion of isolates resistant to clindamycin (13.9 to 31.5%, p<0.001), erythromycin (19.4 to 35.4%, p<0.001) and tetracycline (16.7 to 32%, p<0.001). The proportion of multi-resistant isolates more than doubled from 14.8 to 39.2%. The increasing AMR trend was reflected in the increase of new strain types and the decrease of previously dominant, non-multi-resistant strains. Patient risk factors associated with (p<0.001) the acquisition of multi-resistant strains included community acquisition, livestock contact, hospital care abroad and immigrant status. ConclusionsNotable increasing AMR trends among MRSA isolates were observed in Southwest Finland, 2007–2016. The shift in patient demographics to younger age groups and community acquisition contributed to the increase in multi-resistant strains. Immigration, contact with hospital environment abroad and contact with livestock were identified as essential risk factors of multi-resistance. The increased level of co-resistance has persisted after 2016.

Hospitalizations among family members increase the risk of MRSA infection in a household.

Estimate the risk for household transmission of Methicillin-Resistant Staphylococcus aureus (MRSA) following exposure to infected family members or family members recently discharged from a hospital. Analysis of monthly MRSA incidence from longitudinal insurance claims using the Merative MarketScan Commercial and Medicare (2001-2021) databases. Visits to inpatient, emergency department, and outpatient settings. Households with ≥2 family members enrolled in the same insurance plan for the entire month. We estimated a monthly incidence model, where enrollees were binned into monthly enrollment strata defined by demographic, patient, and exposure characteristics. Monthly incidence within each stratum was computed, and a regression analysis was used to estimate the incidence rate ratio (IRR) associated with household exposures of interest while accounting for potential confounding factors. A total of 157,944,708 enrollees were included and 424,512 cases of MRSA were identified. Across all included enrollees, exposure to a family member with MRSA in the prior 30 days was associated with significantly increased risk of infection (IRR: 71.03 [95% CI, 67.73-74.50]). After removing enrollees who were hospitalized or exposed to a family member with MRSA, exposure to a family member who was recently discharged from the hospital was associated with increased risk of infection (IRR: 1.44 [95% CI, 1.39-1.49]) and the risk of infection increased with the duration of the family member's hospital stay (P value < .001). Exposure to a recently hospitalized and discharged family member increased the risk of MRSA infection in a household even when the hospitalized family member was not diagnosed with MRSA.

Rapid identification and subsequent contextualization of an outbreak of methicillin-resistant Staphylococcus aureus in a neonatal intensive care unit using nanopore sequencing.

Outbreaks of methicillin-resistant Staphylococcus aureus (MRSA) are well described in the neonatal intensive care unit (NICU) setting. Genomics has revolutionized the investigation of such outbreaks; however, to date, this has largely been completed retrospectively and has typically relied on short-read platforms. In 2022, our laboratory established a prospective genomic surveillance system using Oxford Nanopore Technologies sequencing for rapid outbreak detection. Herein, using this system, we describe the detection and control of an outbreak of sequence-type (ST)97 MRSA in our NICU. The outbreak was identified 13 days after the first MRSA-positive culture and at a point where there were only two known cases. Ward screening rapidly defined the extent of the outbreak, with six other infants found to be colonized. There was minimal transmission once the outbreak had been detected and appropriate infection control measures had been instituted; only two further ST97 cases were detected, along with three unrelated non-ST97 MRSA cases. To contextualize the outbreak, core-genome single-nucleotide variants were identified for phylogenetic analysis after de novo assembly of nanopore data. Comparisons with global (n=45) and national surveillance (n=35) ST97 genomes revealed the stepwise evolution of methicillin resistance within this ST97 subset. A distinct cluster comprising nine of the ten ST97-IVa genomes from the NICU was identified, with strains from 2020 to 2022 national surveillance serving as outgroups to this cluster. One ST97-IVa genome presumed to be part of the outbreak formed an outgroup and was retrospectively excluded. A second phylogeny was created using Illumina sequencing, which considerably reduced the branch lengths of the NICU isolates on the phylogenetic tree. However, the overall tree topology and conclusions were unchanged, with the exception of the NICU outbreak cluster, where differences in branch lengths were observed. This analysis demonstrated the ability of a nanopore-only prospective genomic surveillance system to rapidly identify and contextualize an outbreak of MRSA in a NICU.

Modeling relaxed policies for discontinuation of methicillin-resistant Staphylococcus aureus contact precautions.

To evaluate the economic costs of reducing the University of Virginia Hospital's present "3-negative" policy, which continues methicillin-resistant Staphylococcus aureus (MRSA) contact precautions until patients receive 3 consecutive negative test results, to either 2 or 1 negative. Cost-effective analysis. The University of Virginia Hospital. The study included data from 41,216 patients from 2015 to 2019. We developed a model for MRSA transmission in the University of Virginia Hospital, accounting for both environmental contamination and interactions between patients and providers, which were derived from electronic health record (EHR) data. The model was fit to MRSA incidence over the study period under the current 3-negative clearance policy. A counterfactual simulation was used to estimate outcomes and costs for 2- and 1-negative policies compared with the current 3-negative policy. Our findings suggest that 2-negative and 1-negative policies would have led to 6 (95% CI, -30 to 44; P < .001) and 17 (95% CI, -23 to 59; -10.1% to 25.8%; P < .001) more MRSA cases, respectively, at the hospital over the study period. Overall, the 1-negative policy has statistically significantly lower costs ($628,452; 95% CI, $513,592-$752,148) annually (P < .001) in US dollars, inflation-adjusted for 2023) than the 2-negative policy ($687,946; 95% CI, $562,522-$812,662) and 3-negative ($702,823; 95% CI, $577,277-$846,605). A single negative MRSA nares PCR test may provide sufficient evidence to discontinue MRSA contact precautions, and it may be the most cost-effective option.

Prevalence and antimicrobial susceptibility pattern of methicillin-resistant Staphylococcus aureus (MRSA) at a maternity and children hospital in Saudi Arabia: A cross-sectional study

BackgroundMethicillin-resistant Staphylococcus aureus (MRSA) pathogens are considered a serious global health threat, leading to increased mortality and antimicrobial resistance. Rates in Saudi Arabia remain high, necessitating continuous surveillance. This study investigates MRSA prevalence and susceptibility at a Saudi maternity and children's hospital. MethodA cross-sectional study was conducted on pediatric (<18 years) and maternal patients with S. aureus infection from Jan. 2020 to March. 2022. Bacterial strains were obtained from patient’s clinical specimens and was identified by standard method. The BD Phoenix™ M50 was used for antibiotic susceptibility tests and MRSA detection. Data were analysed using descriptive and inferential statistics (Chi-square test) with SPSS software. ResultsOut of 152 S. aureus cases, 114/152 (75 %) were pediatric and 38/152 (25 %) were maternal patients. The overall MRSA infection was 69/152 (45.4 %). Among pediatrics, 31/54 (57.4 %) MRSA cases were female; over 30/54 (56 %) were under 1 year old; and most MRSA infections were obtained from skin 29/54 (53.7 %) compared to other sites of infections (p = 0.024). Among maternal cases, 15/38 (39.5 %) were MRSA, primarily from wound infections 14/15 (93.3 %) compared to other sites of infections (p = 0.39). All MRSA isolates were sensitive to vancomycin and linezolid. While 51/60(85 %) were sensitive to Trimethoprim/ sulfamethoxazole. ConclusionThis investigation found a high prevalence of MRSA among pediatrics and maternal inpatients, indicating a significant burden. All MRSA isolates were susceptible to vancomycin but demonstrated variable sensitivity to other antibiotics. These findings highlight the need for ongoing surveillance, infection control strategies, and research into alternative treatment options to combat this major public health threat.

Staphylococcal aureus outbreaks in neonatal intensive care units: strategies, nuances, and lessons learned from the frontline.

Methicillin-resistant Staphylococcus aureus (MRSA) infections in neonates can result in significant morbidity and mortality. However, comparatively to adults, neonatal MRSA data remains relatively scarce. Additionally, while evidence-driven practices for adults have seen considerable progress, neonatal infection prevention strategies remain poorly described. The Leeds Newborn Service adopted a series of infection prevention and control (IPC) measures following a rise in MRSA cases in 2008-2009. This narrative review presents IPC measures for neonatal MRSA and methicillin-sensitive Staphylococcus aureus (MSSA) infections and reflects upon local challenges and successes of these interventions. Our experience underscores the importance of an adaptive, evidence-based strategy, tailored to the neonatal population. Effectively addressing MRSA/MSSA requires continuous monitoring with sustained targeted interventions. Our key learning points highlight the intertwined difficulties of specific neonatal requirements and lack of definitive IPC guidance, suggesting a holistic approach is key for successful IPC outcomes in the neonatal intensive care unit setting.

Whole-Genome Sequencing-Based Screening of MRSA in Patients and Healthcare Workers in Public Hospitals in Benin.

Methicillin-resistant Staphylococcus aureus (MRSA) constitutes a serious public health concern, with a considerable impact on patients' health, and substantial healthcare costs. In this study, patients and healthcare workers (HCWs) from six public hospitals in Benin were screened for MRSA. Strains were identified as MRSA using conventional microbiological methods in Benin, and confirmed using matrix-assisted laser desorption/ionization time-of-flight mass spectrometry in Belgium. Whole-genome sequencing (WGS) was used on the confirmed MRSA isolates, to characterize their genomic content and study their relatedness. Amongst the 305 isolates (304 wound swabs and 61 nasal swabs) that were collected from patients and HCWs, we detected 32 and 15 cases of MRSA, respectively. From this collection, 27 high-quality WGS datasets were obtained, which carried numerous genes and mutations associated with antimicrobial resistance. The mecA gene was detected in all the sequenced isolates. These isolates were assigned to five sequence types (STs), with ST8 (55.56%, n = 15/27), ST152 (18.52%, n = 5/27), and ST121 (18.52%, n = 5/27) being the most common. These 27 isolates carried multiple virulence genes, including the genes encoding the Panton-Valentine leukocidin toxin (48.15%, n = 13/27), and the tst gene (29.63%, n = 8/27), associated with toxic shock syndrome. This study highlights the need to implement a multimodal strategy for reducing the risk of the cross-transmission of MRSA in hospitals.

Investigation and mapping of the prevalence of “superbugs” Methicillin-resistant Staphylococcus aureus (MRSA) and antimicrobial susceptibility pattern in Enugu metropolis in Southeast Nigeria

Global public health is threatened by increasing incidence of Antimicrobial resistance (AMR). Methicillin-Resistant Staphylococcus aureus (MRSA), usually referred to as “superbug, is a prominent AMR that is generating concerns across the world. They are resistant to commonly used antibiotics, thereby making treatment of common infections very difficult; resulting in prolonged illness and hospitalisation, disability and in some cases, death. Despite the concerns and threats posed by MRSA, studies of its prevalence in communities across Nigeria are scanty. Here, we investigated the prevalence of MRSA in the South East Nigeria using isolates obtained from two major hospitals in Enugu metropolis and a medical laboratory. The isolates were clinically identified from different specimens and pure isolates were subjected to antimicrobial susceptibility profiling using conventional antibiotics. Geographic Information System (GIS) techniques were used to analyse the anonymised three year MRSA records. This provided relevant insights on the spatial spread of MRSA in the city. This research serves as a first step towards modelling its spatial epidemiology in the region. Results indicated that cases of MRSA were widespread in the city. Majority of MRSA were resistant to the antibiotics indicating that they are multidrug-resistant (MDR). Spatiotemporal analyses conducted showed that incidence of MRSA was increasing by the year.

Risk factors for the transmission of Clostridioides difficile or methicillin-resistant Staphylococcus aureus in acute care

Background: Some hospitals continue to struggle with nosocomial transmission of Clostridioides difficile infection (CDI) and methicillin-resistant Staphylococcus aureus (MRSA) despite years of infection control efforts. We investigated the relationship between unit infrastructural–organizational risk factors and nosocomial transmission of CDI and MRSA. Methods: This retrospective observational study included 100 eligible acute-care inpatient units from 12 hospitals in British Columbia, Canada, from April 1, 2020, to September 16, 2021. The outcome variables included whether a unit was on the CDI or MRSA vulnerable unit list (ie, defined as having ≥5 CDI cases or ≥6 MRSA cases being attributed to the unit in the last 6 fiscal periods), the average CDI/MRSA rate, as well as the average CDI/MRSA standardized infection ratio (SIR). Independent variables included, but were not limited to, infection control factors (eg hand hygiene rate), infrastructural factors (eg, unit age, total beds on unit), and organizational factors (eg, hallway bed utilization, nursing overtime). Multivariable regression was performed to identify statistically significant risk factors using SAS, R Studio, and Stata software. Results: For CDI, older units were associated with higher odds of being on the CDI vulnerable unit list (aOR, 1.086; 95% CI, 1.024–1.175), higher CDI rate (adjusted relative risk [aRR], 0.012; 95% CI, 0.004–0.020), and higher CDI SIR (aRR, 0.011; 95% CI, 0.003–0.020). Larger unit size was associated with higher odds of being on the CDI vulnerable unit list (aOR, 1.210; 95% CI, 1.095–1.400) and higher CDI SIR (aRR, 0.013; 95% CI, 0.001–0.026). For MRSA, an increase in hand hygiene rate was associated with lower odds of being on the MRSA vulnerable unit list (aOR, 0.71; 95% CI, 0.53–0.897), lower MRSA rate (aRR, −0.035; 95% CI, −0.063 to −0.008), and lower MRSA SIR (aRR, −0.039; 95% CI, −0.069 to −0.008). Higher MRSA bioburden was associated with higher odds of being on the MRSA vulnerable unit list (aOR, &gt;999; 95% CI, &gt;999 to &gt;999), higher MRSA rate (aRR, 9.008; 95% CI, 5.586–12.429), and higher MRSA SIR (aRR, 4.964; 95% CI, 1.971–7.958). Additionally, higher MRSA rates were associated increased utilization of hallway beds (aRR, 0.680; 95% CI, 0.094–1.267), increased nursing overtime rate (aRR, 5.018; 95% CI, 1.210–8.826), and not having a clean supply room with the door consistently closed (aRR, −0.283; 95% CI, −0.536 to −0.03). Conclusions: Several infrastructural and organizational factors were associated with nosocomial transmissions of CDI and MRSA. Further research is needed to investigate the mechanisms by which these factors are associated.Disclosures: None

Clinical and economic burden of bacteremia due to multidrug-resistant organisms in Korea: a prospective case control study

The socioeconomic and clinical burden of multidrug-resistant organisms (MDRO), including methicillin-resistant Staphylococcus aureus (MRSA), vancomycin-resistant enterococci (VRE), multidrug-resistant Acinetobacter baumannii (MRAB), multidrug-resistant Pseudomonas aeruginosa (MRPA), and carbapenem-resistant Enterobacteriaceae (CRE) have not yet been adequately addressed. We prospectively searched for MDRO bacteremia cases with matched controls from 10 hospitals across Korea during a 6-month period in 2017. Patients were classified into the MDRO, susceptible organism, and no-infection groups. The corresponding susceptible or no-infection controls had been selected according to predefined criteria. We collected clinical information and estimated the total additional medical cost due to MDRO infections using the multistate model. During the 6-month period, a total of 486 MDRO bacteremia cases (260, 87, 18, 20, and 101 cases of MRSA, MRAB, MRPA, CRE, and VRE, respectively) were identified. The 90-d mortality rates were 30.4%, 63.2%, 16.7%, 55.0%, and 47.5%, respectively. The additional costs caused by bacteremia were $15 768, $35 682, $39 908, $72 051, and $33 662 per MDRO type, respectively. Based on these 6-month data, the estimated annual number of bacteremia cases due to these five MDRO in Korea were 7979 (4070, 1396, 218, 461, and 1834 cases, respectively). Overall, this caused an estimated 3280 (1237, 882, 36, 254, and 871, respectively) deaths and cost $294 505 002 ($84 707 359, $74 387 364, $10 344 370, $45 850 215, and $79 215 694, respectively) (range $170,627,020-$416,094,679) in socioeconomic loss. A tremendous clinical and economic burden is caused by MDRO bacteremia compared with antibiotic-susceptible and no-infection groups. Substantial investment and efforts by related government agencies and medical staffs are needed.

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.

Prolonged silent carriage, genomic virulence potential and transmission between staff and patients characterize a neonatal intensive care unit (NICU) outbreak of methicillin-resistant Staphylococcus aureus (MRSA).

Methicillin-resistant Staphylococcus aureus (MRSA) is an important pathogen in neonatal intensive care units (NICU) that confers significant morbidity and mortality. Improving our understanding of MRSA transmission dynamics, especially among high-risk patients, is an infection prevention priority. We investigated a cluster of clinical MRSA cases in the NICU using a combination of epidemiologic review and whole-genome sequencing (WGS) of isolates from clinical and surveillance cultures obtained from patients and healthcare personnel (HCP). Phylogenetic analysis identified 2 genetically distinct phylogenetic clades and revealed multiple silent-transmission events between HCP and infants. The predominant outbreak strain harbored multiple virulence factors. Epidemiologic investigation and genomic analysis identified a HCP colonized with the dominant MRSA outbreak strain who cared for most NICU patients who were infected or colonized with the same strain, including 1 NICU patient with severe infection 7 months before the described outbreak. These results guided implementation of infection prevention interventions that prevented further transmission events. Silent transmission of MRSA between HCP and NICU patients likely contributed to a NICU outbreak involving a virulent MRSA strain. WGS enabled data-driven decision making to inform implementation of infection control policies that mitigated the outbreak. Prospective WGS coupled with epidemiologic analysis can be used to detect transmission events and prompt early implementation of control strategies.

Predictive Role of Targeted, Active Surveillance Cultures for Detection of Methicillin-Resistant Staphylococcus aureus.

IntroductionMethicillin-resistant Staphylococcus aureus (MRSA) colonisation is an important source of healthcare-acquired infections. Reliable screening strategies for MRSA colonisation are essential for the timely implementation of infection control measures.AimThis study determined reliable MRSA screening sites to predict colonisation in resource-limited settings and estimated the impact of missed MRSA cases when shifting from multi- to single-site screening.MethodologyA cross-sectional study was conducted in patients with positive MRSA surveillance cultures from the routinely screened sites (nasal, axillary, groin, and throat) from January 2009 to December 2019.ResultsA total of 1906 screening tests were positive for MRSA cultures (n = 1345 patients). As a single site, the nasal cavity showed the highest MRSA detection, with a sensitivity of 66.8% (95% CI = 64–69) with 277.9 missed isolation days. Screening three or more anatomical sites detected 97–100% of MRSA cases, with 0–24.5 missed isolation days. Screening the axilla and groin separately or in combination showed a good clinical utility index (CUI) of >0.6 to <0.8, while an excellent CUI was obtained upon screening other site samples (>0.8). The combined nasal and throat cultures demonstrated a sensitivity of 93.2 (95% CI = 91–94) with 57.2 missed isolation days.ConclusionMulti-site screening is the optimal strategy for minimising MRSA exposure within a healthcare facility. For active MRSA surveillance, a combination of nasal and throat cultures can provide a practical approach in low-resource settings compared to nasal sampling alone.

Antimicrobial use and resistance data in human and animal sectors in the Lao PDR: evidence to inform policy

ObjectivesTo review the scientific evidence base on antimicrobial use (AMU) and antimicrobial resistance (AMR) in human and animal sectors in the Lao PDR (Laos).MethodsWe reviewed all publications from July 1994...

Successful Treatment of Invasive MRSA Infections in Children Using Area Under the Vancomycin Concentration-Time Curve Divided by the Minimum Inhibitory Concentration (AUC/MIC) to Measure Vancomycin Exposure

Background: Vancomycin is the treatment of choice for invasive methicillin-resistant Staphylococcus aureus (MRSA) infections. Previous guidelines issued by the Infectious Diseases Society of America (IDSA) recommended targeting vancomycin serum trough concentrations of 15–20 mg/L; however, troughs &lt;15 mg/L are also associated with increased odds of renal toxicity. To minimize toxicity, recently updated ASHP/IDSA/PIDS vancomycin dosing guidelines recommend the use of an area under the vancomycin concentration-time curve divided by the minimum inhibitory concentration (AUC/MIC) pharmacodynamic index to measure vancomycin exposure, with an AUC/MIC ratio &gt;400 correlating with clinical efficacy. However, data on vancomycin therapeutic drug monitoring (TDM) in children are limited. Our institutional practice since January 2009 has been to use AUC/MIC, rather than serum trough concentrations, to guide vancomycin dosing. In this study, we describe clinical outcomes in vancomycin-treated children with invasive MRSA infections using this dosing method. Methods: We performed a retrospective chart review of children hospitalized with invasive MRSA infections between 2006 and 2019 at Rady Children’s Hospital in San Diego, California. Clinical, microbiologic, and pharmacologic data including the site of MRSA infection, clinical failure or cure, occurrence of acute kidney injury (AKI), vancomycin MIC, vancomycin AUC, and serum trough concentrations were collected. Results: In total, 61 invasive MRSA cases were reviewed: 20 were admitted January 2016 through December 2008, and 41 were admitted January 2009 through June 2019 (Figure 1). Most patients did not have medical comorbidities. The most common types of infections were primary bacteremia (34%) and osteomyelitis (32%). Of 61 children, 50 (82%) had positive clinical outcomes regardless of vancomycin dosing method. Of 20 patients, 8 (40%) admitted prior to January 2009 developed AKI, compared with 5 (12%) of 41 patients admitted after January 2009. Conclusions: In our retrospective review, most patients had clinically successful outcomes regardless of which dosing strategy was used. We found higher rates of renal toxicity in patients who were admitted prior to 2009, with TDM based on measuring peak and trough concentrations, compared with those using AUC/MIC for TDM. Our findings suggest that AUC/MIC TDM for invasive MRSA infections may be associated with lower rates of renal toxicity.Funding: NoDisclosures: None

Risk factors associated with methicillin-resistant Staphylococcus aureus isolation from serially collected sputum samples of patients hospitalized with pneumonia

IntroductionRisk factors associated with the new detection of methicillin-resistant Staphylococcus aureus (MRSA) during hospitalization remain unclear. This study aimed to identify risk factors associated with MRSA isolation from the sputum of patients admitted with pneumonia, during their hospitalization. MethodsPatients were prospectively enrolled from 2003 to 2012. Sputum samples were collected for bacterial cultures on days 1, 4, 7, 11, and 14 of hospitalization and thereafter. Cases of MRSA first isolated from sputum obtained before day 4 were defined as “carriage on admission.” Cases of MRSA first isolated on day 4 and thereafter, were defined as “new detection after admission.” Statistical analysis was used to investigate the risk factors associated with MRSA isolation. ResultsMRSA was isolated from 167 of 1,008 patients (carriage: 47; new detection: 120). Multivariate analysis revealed that the risk factors for MRSA carriage were activities of daily living (ADL) disability prior to admission (odds ratio [OR], 2.92; 95% confidence interval [CI], 1.37–6.22) and hospitalization within the previous 90 days (OR, 3.75; 95% CI, 1.90–7.41). ADL disability prior to admission (risk ratio [RR], 1.82; 95% CI, 1.17–2.84) and a high pneumonia severity index score upon admission (RR, 2.20; 95% CI, 1.37–3.65) were risk factors for new detection of MRSA. ConclusionsSeveral risk factors were found to be associated with MRSA carriage and/or its new detection, based on the sputum samples from patients admitted with pneumonia. These factors may be indicators for selective surveillance and the early implementation of infection control measures.

Increasing Incidences and Clonal Diversity of Methicillin-Resistant Staphylococcus aureus in the Nordic Countries - Results From the Nordic MRSA Surveillance.

Methicillin-resistant Staphylococcus aureus (MRSA) is notifiable in Denmark, Finland, Iceland, Norway and Sweden. The prevalence of MRSA in this region has been low for many years, but all five countries experience increasing numbers of new cases. The aim of the study was to describe the molecular epidemiology in the Nordic countries 2009-2016. Numbers of new cases of MRSA from 1997 to 2016 were compared, and a database containing information on spa-type and place of residence or acquisition, for all new MRSA isolates from 2009 to 2016 was established. A website was developed to visualize the geographic distribution of the spa-types. The incidence of new MRSA cases increased in all Nordic countries with Denmark having 61.8 new cases per 100,000 inhabitants in 2016 as the highest. The number of new cases 2009 to 2016 was 60,984. spa-typing revealed a high genetic diversity, with a total of 2,344 different spa-types identified. The majority of these spa-types (N = 2,017) were found in 1-10 cases. The most common spa-types t127/CC1, t223/CC22, and t304/CC6:8 increased significantly in all Nordic countries during the study period, except for Iceland, while spa-type t002/CC5 decreased in the same four countries. The trends of other common spa-types were different in each of the Nordic countries. The Nordic countries were shown to share similar trends but also to have country-specific characteristics in their MRSA populations. A continued increasing numbers of MRSA will challenge the surveillance economically. A more selected molecular surveillance will probably have to be employed in the future.

Comparison of Outcomes of Community and Hospital-Acquired Methicillin- Susceptible and Methicillin-Resistant Staphylococcus Aureus Infections

Introduction: Staphylococcus Aureus (S. aureus) causes community (CA) and hospital-acquired (HA) infections that kills millions of patients every year. It is unclear if Methicillin-resistant Staphylococcus Aureus (MRSA) have higher mortality and complication than Methicillin -susceptible Staphylococcus Aureus (MSSA) infections in CA and HA infections. Methods: This retrospective study included confirmed of cases S. aureus infections, which classified as MSSA or MRSA and CA or HA infections We assessed 30-day mortality, rate of Septic Shock and Acute Renal Injury (AKI) as outcomes measures. Results: Of the total 183 cases included, we found no differences between MRSA and MSSA cases in mortality (P=0.734) and other outcomes. Likewise, CA and HA cases Similar mortality. However, HA cases developed a higher rate of AKI compared to CA cases. We observed this increased rate of AKI only in HA MSSA cases. Conclusion: This study offers a new perspective on HA MSSA as a serious pathogen as MRSA, that requires intervention to prevent its spread. Future research needed to identify new measures for MSSA prevention and investigate whether current MRSA prevention strategies are effective in MSSA. Keywords: Methicillin-resistant; MRSA; MSSA; Saudi Arabia; Staphylococcus aureus

Antibiotic Sensitivity to Methicillin and Methicillin Plus Macrolide- Lincosamide-Streptogramins Resistant Staphylococcus Aureus

This study was conducted from May 2018 to Oct 2019 to determine the culture and sensitivity pattern of Methicillin resistant Staphylococcus aureus (MRSA) and MRSA with Macrolide Lincosamide and Streptogramin-B (MLS-B) antibiotics in a tertiary care hospital of Nowshera. A total of 235 isolates were studies and 86 samples showed MRSA. The prevalence rate of MRSA was 89/235 (37.87%). Out of 86 isolates with MRSA, 19 (22.09%) were also resistant to MLS-B antibiotics.Regarding gender specification, 52 (60.5%) were females and 34 (39.5%) were males. The mean age with standard deviation of patients was 29 + 6.8 years. The sensitivity pattern to MRSA was; Vancomycin 100%, Linezolid 100%, Rifampicin 86.04%, Clindamycin, 73.25%, Fusidic acid 60.46%, Erythromycin 44.18%., Doxycyclin 32.55%, levofloxacin 16.27%, Gentamycin 13.95% and Ciprofloxacin 11. 62%. Sensitivity of Vancomycin &amp; Linezolid was 100% in MRSA and MLS-B resistant isolates, and should be kept reserved for MRSA cases to avoid misuse of antibiotics and to reduce resistance.

Methicillin-resistant Staphylococcus aureus development in intensive care patients. A case-control study.

Objectives:To determine the factors associated with the development of methicillin-resistant Staphylococcus aureus (MRSA), hospital stay and mortality, and early versus late MRSA infection.Methods:Cases (n=44) were intensive care unit (ICU) patients admitted to King Fahd Specialist Hospital, Al-Qassim, Saudi Arabia between 2015 and 2019 who developed MRSA during their hospital stay. Controls (n=48) were patients from the same place and period who did not develop MRSA. Data were abstracted from hospital records.Results:Admission with sepsis (case: 46% vs. control: 2%, p<0.001) and having at least one comorbid condition (case: 95% vs. control: 46%, p<0.001) were significantly associated with the development of MRSA. Age (mean ± SD: case: 65±18, control: 64±18, p=0.7) and gender (% male, case: 52%, control: 56%, p=0.70) were not associated with the development of MRSA. Approximately 73% of all MRSA cases developed within the first 2 weeks of admission. Among the early cases, 44% died during their ICU stay; the corresponding percentage among the late cases was 42% (p=0.69). There was no difference between early and late MRSA cases in terms of non-sepsis admissions (50% vs. 67%, p=0.32) or comorbid status (at least one: 97% vs. 92%, p=0.17).Conclusion:Sepsis and comorbid conditions were significant risk factors for MRSA development among hospital patients.