Risk Factors For Methicillin-resistant Staphylococcus Aureus Infection Research Articles

The Prevalence, Epidemiological, and Molecular Characterization of Methicillin-Resistant Staphylococcus aureus (MRSA) in Macau (2017-2022).

Macau, recognized as a global tourism hub and the world's most densely populated region, provides a unique environment conducive to methicillin-resistant Staphylococcus aureus (MRSA) transmission in healthcare and community settings, posing a significant public health concern both locally and globally. The epidemiology and molecular characteristics of MRSA in the distinct city of Macau remain largely unelucidated. This five-year longitudinal study (2017-2022) examined the local prevalence and molecular typing of MRSA in Macau, with future MRSA type distribution predicted through ARIMA modeling. We subsequently analyzed the epidemiological characteristics of MRSA, including specimen source, clinical department, collection year, season, patient age, sex, and the annual number of tourists. Comprehensive antibiotic resistance profiles of the strains were also assessed. Of 504 clinically isolated S. aureus strains, 183 (36.3%) were identified as MRSA by the cefoxitin disk diffusion method and validated through multi-locus sequence typing (MLST). The MRSA detection rate showed an upward trend, increasing from 30.1% in 2017 to 45.7% in 2022. SCCmec type IV was predominant (28.9%), followed by types II (25.4%), III (22.1%), and V (22.1%). The primary sources of MRSA isolates were sputum (39.2%) and secretions (25.6%). Older age emerged as a risk factor for MRSA infection, whereas no significant associations were found with seasonal variations, gender, or the annual number of tourists. Despite displaying universal resistance to cefoxitin, oxacillin, and benzylpenicillin, MRSA isolates in Macau remained fully sensitive to vancomycin, tigecycline, quinupristin, nitrofurantoin, and linezolid. Continuous surveillance and analysis of MRSA distribution in Macau could provide invaluable insights for the effective management of MRSA prevention and control measures within healthcare settings.

Predictors of hospital mortality and multidrug-resistant pathogens in hospitalized pneumonia patients residing in the community

Background and objectiveThe 2019 ATS/ADSA guidelines for adult community-acquired pneumonia (CAP) eliminated healthcare-associated pneumonia (HCAP) and considered it to be a form of CAP. This concept, however, was based on studies with relatively small sample sizes. MethodsWe investigated the risk factors of 30-day mortality, and methicillin-resistant Staphylococcus aureus (MRSA) and Pseudomonas aeruginosa infections in patients with pneumonia coming from the community using the Diagnosis Procedure Combination database, a nationwide discharge database of acute care hospitals. Furthermore, we compared these factors between CAP and HCAP. ResultsA total of 272,337 patients aged ≥20 years with pneumonia were grouped into 145,082 CAP patients and 127,255 HCAP patients. The 30-day mortality rate (8.9 % vs.3.3 %), MRSA infection (2.4 % vs. 1.4 %), and Pseudomonas aeruginosa infection (1.6 % vs. 1.0 %) were significantly higher in HCAP than in CAP patients. Multivariable logistic regression analysis showed that 12 of 13 identified predictors of mortality (i.e., high age, male, underweight, non-ambulatory status, bedsore, dehydration, respiratory failure, consciousness disturbance, hypotension, admitted in critical care, comorbidity of heart failure, and chronic obstructive pulmonary disease) were identical in CAP and HCAP patients. Similarly, five of six distinct risk factors for MRSA infection, and three of three for Pseudomonas aeruginosa infection were identical between the patients. ConclusionThe risk factors for mortality and MRSA or Pseudomonas aeruginosa infection were almost identical in patients with CAP and HCAP. The assessment of individual risk factors for mortality and MRSA or Pseudomonas aeruginosa infection in CAP and abandoning categorization as HCAP can improve and simplify empiric therapy.

Epidemiology of Methicillin-resistant and Methicillin-sensitive Staphylococcus aureus infections in Lebanon

Background. Methicillin-resistant Staphylococcus aureus (MRSA) is a prevalent pathogen associated with significant morbidity and mortality. In Lebanon, MRSA rates have recently started to rise. We aimed to determine risk factors for acquiring MRSA and Methicillin-sensitive Staphylococcus aureus (MSSA) infections and identify independent risk factors for in-hospital mortality among patients with S. aureus infection. Methods. We used a case-case-control study design that included patients with infections and compared them to uninfected controls. Two multivariable regression models were constructed to determine variables associated with acquiring MRSA and MSSA infections. We explored independent predictors of mortality in the overall population compared with the MRSA subgroup. Results. 356 patients with S. aureus infections were identified and compared to 208 uninfected controls. A recent history of surgery and underlying diabetes were independent risk factors for acquiring both infections. Having a urinary catheter for more than 6 days and steroid therapy were unique risk factors for MRSA infection (aOR 28.1, 95% CI 3.5-223.6 and 3.7, 95% CI 1.6-8.7, respectively). Risk factors exclusively associated with MRSA infection included ICU admission, acute renal failure, and malignancy. Conclusions. Risk factors associated with MRSA infection are distinct from those associated with MSSA infection. This can be used to risk stratify patients and will aid in choosing empirical antibiotic therapy.

Methicillin-resistant Staphylococcus aureus nasal carriage among patients on haemodialysis with newly inserted central venous catheters.

Although methicillin-resistant Staphylococcus aureus (MRSA) nasal colonization is common among end-stage kidney disease patients undergoing haemodialysis, few studies were focused on MRSA nasal carriers among haemodialysis patients with central venous catheters (CVCs). The aim of this study is to evaluate the risk factors, various clinical outcomes and effect of decolonization for MRSA nasal colonization among patients on haemodialysis via CVCs. This was a single-centre non-concurrent cohort study of 676 patients who had new haemodialysis CVCs inserted. They were all screened for MRSA colonization via nasal swabs and were categorized into two groups: MRSA carriers and MRSA noncarriers. Potential risk factors and clinical outcomes were analysed in both groups. All MRSA carriers were given decolonization therapy and the effect of decolonization on subsequent MRSA infection was also performed. Eighty-two patients (12.1%) were MRSA carriers. Multivariate analysis showed that MRSA carrier (OR 5.44; 95% CI 3.02-9.79), long-term care facility resident (OR 4.08; 95% CI 2.07-8.05), history of Staphylococcus aureus infection (OR 3.20; 95% CI 1.42-7.20) and CVC in situ > 21days (OR 2.12; 95% CI 1.15-3.93) were independent risk factors for MRSA infection. There was no significant difference in all-cause mortality between MRSA carriers and noncarriers. The MRSA infection rates were similar between MRSA carriers with successful decolonization and those who had failed/incomplete decolonization in our subgroup analysis. MRSA nasal colonization is an important cause of MRSA infection among haemodialysis patients with CVCs. However, decolonization therapy may not be effective in reducing MRSA infection.

Methicillin-Resistant Staphylococcus aureus: The Magnitude and Risk Factors among Patients Admitted to Tikur Anbessa Specialized Hospital, Addis Ababa, Ethiopia.

Background In healthcare facilities, a gradual increase in methicillin-resistant Staphylococcus aureus (MRSA) infections has been seen over the past 2 decades. Similarly, it has been responsible for the most frequent and invasive pathogens associated with admitted patient infection. Currently, it is considered an urgent threat to public health and classified as one of the top-priority antimicrobial-resistant pathogens. This study aimed to determine the magnitude and associated risk factors of MRSA infection among admitted patients. Methods A facility-based cross-sectional examination was led on 413 patients admitted to Tikur Anbessa Specialized Hospital from January 2018 to January 2019. A convenient sampling technique was used. Clinical specimens of pus and blood were collected from admitted patients who developed the infection after 48 hours of admission. Gram stain, culture media preparations, and biochemical tests were conducted to identify and isolate the causative agent. Staphylococcus aureus (S. aureus) were identified as MRSA strains after having a zone of inhibition less than or equal to 21 mm to the cefoxitin (30 ug) disc. Bivariate and multivariable logistic regression analyses were computed. The odds ratio, along with 95% CI, was estimated to identify associated risk factors for MRSA infection. Results Out of 413 collected specimens, 38.7% had coagulase-positive S. aureus of which 35.6% (95% CI: 28.2%–43.0%) were MRSA. Being within the age group of 19–29 years and 30–39 years with AOR = 5.02 and 95% CI: 1.24–20.35 and AOR = 6.65 and 95% CI: 1.78–24.78, respectively, admitting in the hematology ward and the pediatric ward with AOR = 7.80 and 95% CI: 1.82–33.49 and AOR = 10.54 and 95% CI: 1.78–62.42, respectively, and experiencing poor prognosis with AOR = 10.97 and 95% CI: 4.57–26.36 were significantly associated with MRSA infection. Conclusion and Recommendation. The significant magnitude of MRSA was found among patients admitted to this hospital. Therefore, identified risk factors should be considered when executing hospital-acquired infection prevention programs. We also suggest that healthcare providers should consider the identified risk factors while prescribing the antibiotic.

The Prevalence, Risk, and Management of Methicillin-Resistant Staphylococcus aureus Infection in Diverse Populations across Canada: A Systematic Review.

Methicillin-resistant Staphylococcus aureus (MRSA) first emerged after methicillin was introduced to combat penicillin resistance, and its prevalence in Canada has increased since the first MRSA outbreak in the early 1980s. We reviewed the existing literature on MRSA prevalence in Canada over time and in diverse populations across the country. MRSA prevalence increased steadily in the 1990s and 2000s and remains a public health concern in Canada, especially among vulnerable populations, such as rural, remote, and Indigenous communities. Antibiotic resistance patterns and risk factors for MRSA infection were also reported. All studies reported high susceptibility (>85%) to trimethoprim-sulfamethoxazole, with no significant resistance reported for vancomycin, linezolid, or rifampin. While MRSA continues to have susceptibility to several antibiotics, the high and sometimes variable resistance rates to other drugs underscores the importance of antimicrobial stewardship. Risk factors for high MRSA infection rates related to infection control measures, low socioeconomic status, and personal demographic characteristics were also reported. Additional surveillance, infection control measures, enhanced anti-microbial stewardship, and community education programs are necessary to decrease MRSA prevalence and minimize the public health risk posed by this pathogen.

Risk factors for wound infection caused by Methicillin Resistant Staphylococcus aureus among hospitalized patients: a case control study from a tertiary care hospital in India.

Methicillin Resistant Staphylococcus aureus (MRSA) causes infection in hospitals and communities. The prevalence and risk factors of MRSA infection is not homogenous across the globe. To find the risk factors of MRSA infection among hospitalized patients. Cross-sectional case control study was conducted at a tertiary care hospital in India. The risk factors were collected using checklist from 130 MRSA and 130 Methicillin sensitive staphylococcus aureus (MSSA) infected patients. The pathogens were isolated from the wound swabs according to Clinical and Laboratory Standards Institute guidelines. Both the groups were comparable in terms of age, gender, diabetic status, undergoing invasive procedures, urinary catheterization and smoking (p>0.05). Multivariate logistic regression revealed surgical treatment (OR 4.355; CI 1.03, 18.328; p=0.045), prolonged hospitalization (OR 0.307; CI 0.11, 0.832; p=0.020), tracheostomy (OR 5.298, CI 1.16, 24.298; p=0.032), pressure/venous ulcer (OR 7.205; CI 1.75, 29.606; p=0.006) and previous hospitalization (OR 2.883; CI 1.25, 6.631; p=0.013) as significant risk factors for MRSA infection. Surgical treatment, prolonged and history of hospitalization, having tracheostomy for ventilation and pressure/venous ulcer were the key risk factors. Therefore, special attention has to be given to the preventable risk factors while caring for hospitalized patients to prevent MRSA infection.

What Are the Risk Factors for Methicillin-resistant Staphylococcus Aureus Infection Among Patients in a Neonatal Intensive Care Unit?

<h3>Background</h3> Outbreaks of methicillin-resistant Staphylococcus aureus (MRSA) often occur in neonatal intensive care units (NICUs). However, few studies investigating relevant risk factors and potential interventions have been conducted. The purpose of the current study was to identify risk factors for MRSA infection in NICU patients. <h3>Methods</h3> The current investigation was a prospective cohort study of newborns admitted to the NICU at a Japanese teaching hospital between 1 July 2002 and 31 December 2008. The following patient-related factors were investigated: birth-weight, gestational age, sex, Apgar score, number of fetuses, length until cord detachment, and eye mucous. The medical factors investigated included type of delivery, inborn/outborn, antimicrobial therapy, use of medical devices, Kangaroo mother care, patient-to-nurse ratio, and MRSA colonization pressure. Cox proportional hazards regression was used to analyze risks of MRSA infection, and hazards ratios (HRs) and confidence intervals (CIs) were calculated. The statistical significance level was set at α = 0.05. <h3>Results</h3> A total of 1608 cases were analyzed, and MRSA was isolated from 282 (17.5%) patients. Significant parameters identified in Cox proportional hazards analysis included caesarean section (HR 1.46, 95% CI 1.10–1.95), eye mucous (HR 1.53, 95% CI 1.15–2.05), administration of the mother's first milk via catheter (HR 1.57, 95% CI 1.03–2.41), umbilical catheter placement (HR 2.05, 95% CI 1.02–4.10), patient-to-nurse ratio (HR 0.12, 95% CI 0.05–0.26), and MRSA colonization pressure (HR 16.79, 95% CI 8.41–33.50). <h3>Conclusions</h3> This study identified the risk factors for MSRA infection and determined that identifying high-risk patients, shortening periods of catheterization, maximizing patient-to-nurse ratios, and reducing MRSA colonization pressure can help reduce MRSA transmission among NICU patients.

Nasal colonization with methicillin-resistant Staphylococcus aureus associated with elevated homocysteine levels in the general US adults.

Given the emergence of community-acquired methicillin-resistant Staphylococcus aureus (MRSA) as a global health threat, understanding the risk factors for MRSA infection in the community may be a reasonable strategy to prevent it. We investigated the associations between serum homocysteine levels and prevalence of nasal colonization with S aureus and MRSA among United States adults. We conducted a cross-sectional analysis of a nationally representative sample of 7832 adults (20 years or older). The main outcome variables were nasal colonization with S aureus and MRSA. Percentages of colonization with S aureus and MRSA were calculated by the quartiles of serum homocysteine. A total of 7832 of 2051 subjects (26.2%) were culture positive for S aureus, 98 (4.8%) of whom had nasal colonization with MRSA. In comparison with subjects having the lowest serum homocysteine, the odds of nasal colonization with MRSA were significantly higher in those with the highest homocysteine (odds ratio, 3.09; 95% confidence interval, 1.11–8.61) in multivariate analysis, adjusted for all confounding variables. By contrast, homocysteine elevation was not significantly associated with S aureus colonization. Nasal colonization with MRSA in the general community was significantly associated with increases in serum homocysteine levels.

Methicillin-resistant Staphylococcus aureus: prevalence of and risk factors associated with colonization of patients on admission to the Teaching hospital, Karapitiya

Methicillin-resistant Staphylococcus aureus (MRSA) causes a substantial burden of community-acquired and nosocomial infection. Prior colonization with MRSA is a recognized risk factor for MRSA infection. The study aimed to assess the prevalence of and risk factors for MRSA colonization at admission to surgical, medical and orthopaedic wards of Teaching Hospital, Karapitiya, Sri Lanka. From September 2016 to March 2017, consecutive patients admitted to orthopaedic wards and every fifth patient admitted to medical and general surgical wards were enrolled. A nasal swab was collected from the anterior nares within 24 hours of admission and tested using standard microbiologic procedures. Clinical and demographic data were collected. A total of 502 patients were enrolled, including 152 medical, 201 general surgical, and 149 orthopaedic patients. The median age was 45 years (range 3- 85 years) and 58% of patients were male. At admission, 31 (6.2%) were colonized with MRSA. Colonization prevalence was higher in orthopaedic (18, 12.1%) compared to medical (6, 4.0%) and general surgical (7, 3.5%) patients, p=0.002. Patients colonized with MRSA on admission were more likely to be children

Prevalence and Risk Factors for Methicillin-Resistant Staphylococcus aureus (MRSA) Infections in Custodial Populations: A Systematic Review.

early identification, isolation, and treatment of skin infections at admission; education on maintaining skin integrity and presenting early with skin infections; increasing hygiene by not sharing items and encouraging handwashing; improved handling and disinfection of communal laundering; influenza vaccination for all prisoners and staff; and population-based longitudinal studies including younger detainees.

Prevalence and characteristics of methicillin-resistant Staphylococcus aureus in community residents of Japan.

BackgroundTo implement effective precautions to avoid methicillin‐resistant Staphylococcus aureus (MRSA) nosocomial infections, it is important to clarify when, how, and from whom MRSA was transmitted to the patients. However, MRSA strains obtained from outpatient population were not analyzed, and the transmission routes of MRSA in the community are not completely understood. The purpose of this study was to clarify whether MRSA is spreading in community settings or whether MRSA transmission still occurs only in healthcare institutions.MethodsSurveillance cultures of 1274 residents living in a community were performed in two different areas, Kochi and Osaka prefectures of Japan. All isolated MRSA strains were evaluated using multilocus sequence typing (MLST) to clarify the transmission routes of MRSA. The results were compared with those of inpatients. Moreover, written questionnaires and medical records were analyzed.ResultsAnalysis of surveillance cultures from residents living in the community in Japan revealed an MRSA colonization rate of 0.94%. The proportion of MRSA to S. aureus colonization was 2.6% in the 310 residents, which was significantly lower than in the 393 hospitalized patients (63.1%; P < .0001). MRSA strains in residents are different from the endemic strains in the hospitalized patients. Previous hospital admission is a risk factor for MRSA infection of the endemic strain in hospital.ConclusionsMethicillin‐resistant Staphylococcus aureus colonization in community setting is rare in Japan. MLST results suggest that some MRSA strains are moving to the community through previous hospital admissions; however, MRSA is not spreading in community settings.

Neonatal methicillin-resistant Staphylococcus aureus colonization and infection.

Methicillin-resistant Staphylococcus aureus (MRSA) is a common etiological agent of a life-threatening infection in neonatal intensive care units (NICUs). Neonates with very low birth weight and patients with serious diseases are more likely to be exposed to invasive procedures which make them at a high risk of MRSA colonization and infection. Since MRSA colonization is a risk factor for MRSA infection, prevention of MRSA transmission is an important issue in NICUs. NICUs in Japan practice standard contact precautions and active surveillance cultures (ASC) to prevent MRSA transmission. In this report, we analyzed the clinical characteristics of MRSA colonization and infection between January 2010 and December 2015 in our perinatal care center. We conducted retrospective analysis of 1716 neonates hospitalized in our perinatal care center. 120 cases had MRSA colonization (6.99%) and among them 33 neonates were infected. The duration of stay (P≤0.001) and the birth weight (P≤0.001) showed statistically significant differences between MRSA-colonized neonates and non-MRSA-colonized neonates. The number of central venous catheterization showed statistically significant differences (P = 0.001) and the number of digestive system diseases showed marginally significant differences (P = 0.072) between MRSA-colonized non-infected neonates and MRSA-infected neonates. As previous reports have shown, we present that the neonates with central venous catheterization were more likely to be infected with MRSA. We also need to pay attention to neonates with digestive system diseases, showing signs of infection, because they may be potentially infected with MRSA.

Methicillin-resistant Staphylococcus aureus in cystic fibrosis: how should it be managed?

Methicillin-resistant Staphylococcus aureus (MRSA) remains prevalent in people with cystic fibrosis (CF). As chronic infection is often associated with worse pulmonary outcomes, the organism is concerning to CF providers and patients. This review describes current epidemiology, our understanding of risk factors for MRSA infection, and relevant aspects of treatment with review of new and ongoing trials. Prevalence ranges from a low of 3 to 4% in some European countries to a high of approximately 26% in the United States. Risk factors for chronic MRSA infection include patient-specific factors such as genotype, pancreatic insufficiency, diabetes and antibiotic use; however, warmer climate also contributes to increased MRSA rates in CF and non-CF. In addition to retrospective reviews, a few clinical trials are being conducted or have been performed showing the successful short-term eradication of incident MRSA. Chronic MRSA remains challenging to eradicate and antibiotics should be dosed to adjust for CF-specific pharmacokinetics. As chronic MRSA will remain a long-term challenge to treat, ongoing effort should focus on the prevention of transmission with a need to better understand patient's environmental and modifiable risk factors. Early treatment appears successful; however, protocols to achieve long-term clearance are lacking.

Empiric Methicillin Resistant Staphylococcus aureus Coverage in the Early Ventilator Associated Pneumonia Window: If and When

Choice of empiric antibiotic(s) for early ventilator associated pneumonia (VAP) involves weighing the risks of potential infection with multi-drug resistant (MDR) pathogens against those of over-exposure to broad-spectrum agents. Although early VAP is believed to be rarely caused by MDR pathogens, the overall incidence of all methicillin resistant Staphylococcus aureus (MRSA) infections is increasing. We questioned if MRSA VAP is becoming more common and if these infections were occurring earlier in the patient's hospital course. We hypothesized that 1) early (2-4 d from intubation) VAP caused by MRSA is relatively uncommon and 2) those patients with early VAP because of MRSA had risk factors associated with a MDR organism infection. Bronchoscopies with lavage (BALs) from patients admitted to our SICU from 2010-2013 were reviewed. MRSA VAP was defined as growth of ≥10(5) cfu/mL from BAL. Multi-drug resistant risk factors included a previous MRSA infection or positive nasal swab, antibiotic use within 90 d, hospitalization for >5 d, hemodialysis, homelessness, intravenous drug use, and men having sex with men. In the 3-y period, there were 438 cases of VAP. Forty-seven specimens from 43 patients had quantitative microbiologic confirmation of MRSA VAP for an overall prevalence of 10.7%. Of patients with early VAP, three of 106 (2.8%) were MRSA positive. Culture results were graphed according to ventilator days ( Fig. 1 ). The median days ventilated at the time of MRSA VAP were 8 d (range 2-81). All of the early MRSA VAP patients had identifiable risk factors for MRSA infection. The negative predictive value for patients not having a risk factor was one. These data suggest that the incidence of MRSA VAP is stable. Those patients with early MRSA VAP demonstrated traditional MDR risk factors. Patients without risk factors in the early time period could effectively be ruled out from having MRSA VAP and likely do not require empiric MRSA coverage.

Methicillin-resistant Staphylococcus aureus eradication in young infants should include the diaper area and treat housing contacts.

Methicillin-resistant Staphylococcus aureus (MRSA) causes community and healthcare associated infections in all age groups and treatment can be difficult due to its resistance against methicillin and other antimicrobials. The disease spectrum ranges from superficial skin and soft tissue infections (SSTI) (1) to life-threatening invasive infections (2). Colonisation is age-dependent (3) and often precedes infection (1). Other risk factors for MRSA infections in children are not well established. We aimed to characterise paediatric MRSA infections to assess potential risk factors for transmission and infection in children in a single centre in Switzerland, a country with a very low prevalence of MRSA, at less than 1% (4). This article is protected by copyright. All rights reserved.

Risk factors for methicillin-resistant Staphylococcus aureus skin and soft tissue infection in MRSA-colonized patients discharged from a Veterans Affairs hospital.

Currently, limited studies have quantified the risk of methicillin-resistant Staphylococcus aureus (MRSA) skin and soft tissue infections (SSTIs) for MRSA-colonized patients on discharge from hospital. Our retrospective, case-control study identified independent risk factors for the development of MRSA SSTIs among such patients detected by active MRSA nasal screening in an acute care hospital by PCR on admission, and bacteriological cultures on discharge. Cases were MRSA-colonized patients aged ⩾18 years who developed a MRSA SSTI post-discharge and controls were those who did not develop a MRSA SSTI post-discharge. Controls were matched to cases by length of follow-up (±10 days) for up to 18 months. Potential demographic and clinical risk factors for MRSA infection were identified using electronic queries and manual chart abstraction; data were compared by standard statistical tests and variables with P values ⩽0·05 in bivariable analysis were entered into a logistic regression model. Multivariable analysis demonstrated prior hospital admission within 12 months (P = 0·02), prior MRSA infection (P = 0·05), and previous myocardial infarction (P = 0·01) were independently predictive of a MRSA SSTI post-discharge. Identification of MRSA colonization upon admission and recognition of risk factors could help identify a high-risk population that could benefit from MRSA SSTI prevention strategies.

Staphylococcus aureus bacteraemia in Gauteng academic hospitals, South Africa

Methicillin-resistant Staphylococcus aureus (MRSA) infections are responsible for longer hospital stays, increased hospital costs, and poorer outcomes compared to methicillin-sensitive S. aureus (MSSA) infections. We aimed to describe the epidemiology of S. aureus bacteraemia (SAB) and to determine factors associated with MRSA infection in South Africa. Cases of SAB were reported from September 2012 to September 2013 from three sentinel sites. A case was defined as the isolation of S. aureus from a blood culture during a 21-day period. Detailed clinical information was collected. Multivariable logistic regression was done to determine factors associated with MRSA infection and mortality. There were 442 cases of SAB reported; antimicrobial susceptibility testing was performed on 240 isolates (54%). Thirty-six percent (86/240) of cases had an MRSA infection. A longer hospital stay before positive specimen collection (odds ratio (OR) 1.08, 95% confidence interval (CI) 1.02-1.13, p=0.004), hospitalization in the last year (OR 15.7, 95% CI 2.5-99.5, p=0.003), HIV infection (OR 4.9, 95% CI 1.05-22.90, p=0.044), and antibiotic use in the previous 2 months (OR 0.1, 95% CI 0.01-0.68, p=0.022) were independent predictors of MRSA. Older age, and in particular age 25-44 years (OR 22.2, 95% CI 2.7-185.5, p=0.004, compared to those aged<5 years), was the only independent predictor of mortality amongst cases with SAB. MRSA isolates were non-susceptible to more antimicrobial agents compared to MSSA isolates. HIV infection was an independent risk factor for MRSA infection. The selection of appropriate empirical antimicrobial treatment is essential in patients with MRSA infections because of non-susceptibility to many other antimicrobial classes.

Risk factors for MRSA infection in companion animals: Results from a case–control study within Germany

Increasing numbers of companion animals suffering from infections with methicillin-resistant Staphylococcus aureus (MRSA) have been reported in the recent past. These infections are of particular concern because of the limited treatment options for MRSA and their transferability to humans. Since MRSA lineages isolated from infected companion animals often mirror typical human epidemic strains circulating in the same region, successful strategies to combat MRSA need strong and coordinated efforts from both, the human and the veterinary field according to the “One Health” concept. Hence, to identify potential risk factors related to MRSA infections in dogs, cats and horses, a case–control study was conducted, including data on 106 MRSA-infected animal patients as cases and 102 MSSA-infected animals as controls, originating from 155 different veterinary settings within Germany. Demographic data on animal patients, patient history and administration of antibiotics as well as practice/clinic specific parameters were assessed as putative risk factors. Multivariable logistic regression identified the following variables as risk factors for MRSA infection compared to MSSA infection: number of employees working at the veterinary setting (n>10; p<0.001), antibiotic treatment prior to sampling (systemic: p=0.002; local: p=0.049, both: p=0.011) and surgical site infection (p<0.001). Spa typing revealed predominantly clonal complexes well-known for hospital-associated lineages spreading in human health-care settings in Germany (CC5 and CC22) for isolates of dog and cat origin. CC398-MRSA dominated among equine isolates, a CC that was described as a nosocomial pathogen in equine clinical settings before.The identified risk factors and genotyping results are in accordance with numerous study outcomes from the field of human medicine and point towards reasonable problems with nosocomial spread of MRSA, especially within companion animal veterinary clinics. To define targeted infection control strategies against nosocomial pathogens, it is important to accomplish intervention studies addressing routes of transmission in companion animal veterinary settings.

Active surveillance to determine the impact of methicillin resistance on mortality in patients with bacteremia and influences of the use of antibiotics on the development of MRSA infection

Methicillin-resistant Staphylococcus aureus (MRSA) is among the most important pathogens of nosocomial infections, mainly in intensive care units (ICUs), and accounts for 40-60% of all healthcare-associated S. aureus infections. We evaluated the incidence of nosocomial infection by S. aureus, identified the risk factors for MRSA infection, and evaluated the effect of resistance to methicillin on mortality in patients. We conducted MRSA surveillance at a university hospital in Brazil from January 1, 2010, to December 31, 2010, and performed a retrospective case-control matched study to evaluate the frequency of subsequent MRSA bacteremia and death among patients. We evaluated and compared the risk factors between patients with MRSA and methicillin-sensitive Staphylococcus aureus (MSSA) infection. Sepsis was the most common cause of infection (17.7/1,000 patient-days), followed by surgical site (11.4/1,000 patient-days), pneumonia (4.1/1,000 patient-days), and urinary tract infection (2.4/1,000 patient-days). The significant risk factors were time of hospitalization, use of central vascular catheter (CVC), urinary catheter, nasogastric tube, parenteral nutrition, tracheostomy, mechanical ventilation, and previous antibiotic administration, the latter of which was the only independent risk factor for MRSA infection. Mortality was significantly higher in patients with MRSA. The number of antibiotics tested was not related to increases in the frequency of MRSA/1,000 patient-days. The incidence of mortality attributable to MRSA (bloodstream infection) BSI was 50%. Surveillance results showed that the use of high levels of antibiotics was directly related to the development of MRSA infection, and the mortality attributable to MRSA in patients with bacteremia was significant.