MRSA Colonization Research Articles

Preventing Transmission of HIV--A Special Symposium

A Dutch medical student has the potentially more virulent Panton-Valentine leukocidin (PVL) form of MRSA colonization yet shows no signs or symptoms of infection. More than a year ago, a routine MRSA screening of health care personnel providing care for MRSA-positive patients detected the colonization. Since then, the student has been treated intensively but unsuccessfully in an attempt to decolonize her. During this decolonization period, the medical student was barred from performing patient-related interventions, temporarily interrupting her medical residency. After initial treatment with mupirocin nasal ointment and antibiotics proved ineffective, a more stringent hygiene regime was added that included hand, nose, hair, and body scrubbing with disinfecting soap. Additional precautions included simultaneous treatment of household members and disinfection of the family home. Despite these efforts, her MRSA status has remained positive. WIP guideline s bar any health care worker diagnosed with MRSA from performing patient-related interventions. Unable to complete the residency requirement of at least 1 year of patient care, the medical student was advised to pursue a career in another profession.

Knowledge, Awareness, and Attitudes Regarding Methicillin-Resistant Staphylococcus Aureus among Caregivers of Hospitalized Children

To explore knowledge, awareness, and attitudes among caregivers of hospitalized children with regard to methicillin-resistant Staphylococcus aureus (MRSA). We developed and administered a bedside questionnaire to caregivers of hospitalized children in contact isolation for MRSA colonization or infection. Of 104 caregivers approached, 100 (96%) consented to participate. The caregivers' children included 28 (28%) newly recognized as colonized or infected with MRSA during the hospitalization and 72 (72%) previously identified as colonized or infected with MRSA. Eighteen (18%) caregivers had no knowledge of MRSA. Twenty-nine (29%) were unaware that their child had MRSA, including caregivers of 9 newly identified patients with MRSA and 20 patients with previously identified MRSA. Of the 71 caregivers aware of their child's MRSA status, 89% had concerns; 77% worried about risks of future MRSA infection, 51% worried about spreading MRSA, and 16% described a feeling of stigma. Worries were more common among caregivers of children with newly identified MRSA (P < .05). Caregivers of children hospitalized with MRSA are frequently unaware that their child has MRSA. Among those aware of their child's MRSA status, many have concerns and worries. Caregivers of children with newly identified MRSA more often are worried and may need additional education and reassurance.

Study on the relationship between colonization pressure and MRSA cross transmission among hospitalized patients

Objective Based on active monitoring MRSA carriage for hospitalized patients, the relationship between colonization pressure and MRSA cross transmission in wards without rigorous contactisolation measures was analyzed, and the role of colonization pressure in predicting MRSA cross transmission was further evaluated. Methods From March to December 2009, active MRSA colonization screening was performed for 240 hospitalized patients in emergency ward and 94 cases in RICU in our hospital. rep-PCR method was employed to do homology analysis on MRSA strains obtained in this study. MRSA weekly colonization pressure, threshold colonization pressure ,cross transmission rate were calculated respectively. RR of MRSA cross transmission under higher level of colonization pressure and lower level of colonization pressure was analyzed. Results MRSA carriage rates on admission for patients in emergency wards and RICU were 6. 25% (15/2A0) and 13. 83 % (13/94) ,and MRSA cross transmission occurred in 13 weeks and 14 weeks in above two units, respectively. Threshold colonization pressures for above two units were 6. 49%and 17. 66%, respectively. For emergency ward, the MRSA cross transmission rate under higher level of colonization pressure was significantly higher than that under lower level of colonization pressure (x2 = 7. 10,P＜0. 01), the RR of MRSA transmission was 9. 61 (95% CI:1. 25-74.00). For RICU, the MRSA cross transmission rate under higher level of colonization pressure was significantly higher than that under lower level of colonization pressure(x2 = 12. 60, P＜0. 01 ), the RR of MRSA transmission was 15.87 (95% CI:2. 06-122. 10). Conclusions Higher level of colonization pressure is an important risk factor for MRSA transmission, and average colonization pressure can be used as a prediction index for MRSA transmission and strengthening prevention and control measures. Key words: Methicillin resistance; Staphylococcus aureus; Staphylococcal infections; Cross infection

P17.15 The point prevalence study of MRSA colonization in long-term-care facilities in the elderly acute care population in Krakow, Poland

P17.15 The point prevalence study of MRSA colonization in long-term-care facilities in the elderly acute care population in Krakow, Poland

P29.24 The value of nasal swabs, multiple body site screening and clinical risk assessment to detect MRSA colonisation in pathfinder hospitals in Scotland

P29.24 The value of nasal swabs, multiple body site screening and clinical risk assessment to detect MRSA colonisation in pathfinder hospitals in Scotland

P29.25 Development of a clinical risk assessment tool to predict MRSA colonisation on admission to hospital

P29.25 Development of a clinical risk assessment tool to predict MRSA colonisation on admission to hospital

Natural history of meticillin-resistant Staphylococcus aureus colonisation among residents in community long term care facilities in Spain

The spread of meticillin-resistant Staphylococcus aureus (MRSA) is a major problem for both acute care hospitals and among residents in long term care facilities (LTCFs). We performed a cohort study to assess the natural history of MRSA colonisation in LTCF residents. Two cohorts of residents (231 MRSA carriers and 196 non-carriers) were followed up for an 18 month period, with cultures of nasal and decubitus ulcers performed every six months. In the MRSA carrier cohort, 110 (47.8%) residents had persistent MRSA colonisation for six months or longer, 44 (19.0%) had transient colonisation and nine (3.9%) were intermittently colonised. No risk factors for persistent MRSA colonisation could be determined. The annual incidence of MRSA acquisition was around 20% [95% confidence interval (CI): 14.3-25.5]. Antibiotic treatmentwas independently associated with MRSA acquisition (odds ratio: 2.27; 95% CI:1.05-4.88; P=0.03). Just two clones were distinguishable by pulsed-field gel electrophoresis and multilocus sequence typing: CC5-MRSA IV, which is widely disseminated in Spanish hospitals, and ST22-MRSA IV. This study adds to the knowledge of the epidemiology of MRSA in community LTCFs, which are important components of long term care in Spain.

Prevention of MRSA Colonization and Control of Resistance of Mupirocin in NICU Patients

Prevention of MRSA Colonization and Control of Resistance of Mupirocin in NICU Patients

The impact of methicillin-resistant Staphylococcus aureus colonisation on paediatric cystic fibrosis patients’ morbidity

BackgroundMethicillin-resistant Staphylococcus aureus (MRSA) plays a well-recognised pathogenic role in cystic fibrosis (CF). AimsTo evaluate the prevalence and incidence of colonisation by MRSA, clinical impact of MRSA colonisation (year after first MRSA isolation), risk factors and pattern of antimicrobial resistance. MethodsRetrospective review of paediatric CF patients colonised with MRSA followed-up at the CF Unit of Hospital de Santa Maria 2003–2007. ResultsTwelve of the 60 patients followed-up during this period were MRSA-positive at some time (chronic colonisation in 3 patients). Mean age at acquisition was 9 years 10 months and mean time interval between CF diagnosis and MRSA acquisition 5 years 7 months.An important rise in MRSA colonisation prevalence and incidence was observed, with the highest rate seen in 2007 (prevalence 14.3% and incidence 8.9%).Four patients had received anti-staphylococcal prophylaxis with flucloxacillin.An increase in the total number of in-patient days was observed in four patients (two with chronic colonisation). Deterioration in lung function was seen in five patients (including the three patients with chronic colonisation). Only one patient had a decrease in body mass index percentile.Resistance to clindamycin and rifampin was the most frequently seen. ConclusionsThis study revealed significant clinical deterioration in patients with chronic colonisation by MRSA, reinforcing the importance of effective and timely decolonisation strategies.

Methicillin resistant Staphylococcus aureus ST398 in veal calf farming: human MRSA carriage related with animal antimicrobial usage and farm hygiene.

IntroductionRecently a specific MRSA sequence type, ST398, emerged in food production animals and farmers. Risk factors for carrying MRSA ST398 in both animals and humans have not been fully evaluated. In this cross-sectional study, we investigated factors associated with MRSA colonization in veal calves and humans working and living on these farms.MethodsA sample of 102 veal calf farms were randomly selected and visited from March 2007–February 2008. Participating farmers were asked to fill in a questionnaire (n = 390) to identify potential risk factors. A nasal swab was taken from each participant. Furthermore, nasal swabs were taken from calves (n = 2151). Swabs were analysed for MRSA by selective enrichment and suspected colonies were confirmed as MRSA by using slide coagulase test and PCR for presence of the mecA-gene. Spa types were identified and a random selection of each spa type was tested with ST398 specific PCR. The Sequence Type of non ST398 strains was determined. Data were analyzed using logistic regression analysis.ResultsHuman MRSA carriage was strongly associated with intensity of animal contact and with the number of MRSA positive animals on the farm. Calves were more often carrier when treated with antibiotics, while farm hygiene was associated with a lower prevalence of MRSA.ConclusionThis is the first study showing direct associations between animal and human carriage of ST398. The direct associations between animal and human MRSA carriage and the association between MRSA and antimicrobial use in calves implicate prudent use of antibiotics in farm animals.

Staphylococcus aureusNasal Colonization and Subsequent Infection in Intensive Care Unit Patients: Does Methicillin Resistance Matter?

Staphylococcus aureus is an important cause of infection in intensive care unit (ICU) patients. Colonization with methicillin-resistant S. aureus (MRSA) is a risk factor for subsequent S. aureus infection. However, MRSA-colonized patients may have more comorbidities than methicillin-susceptible S. aureus (MSSA)-colonized or noncolonized patients and therefore may be more susceptible to infection on that basis. To determine whether MRSA-colonized patients who are admitted to medical and surgical ICUs are more likely to develop any S. aureus infection in the ICU, compared with patients colonized with MSSA or not colonized with S. aureus, independent of predisposing patient risk factors. Prospective cohort study. A 24-bed surgical ICU and a 19-bed medical ICU of a 1,252-bed, academic hospital. A total of 9,523 patients for whom nasal swab samples were cultured for S. aureus at ICU admission during the period from December 2002 through August 2007. Patients in the ICU for more than 48 hours were examined for an ICU-acquired S. aureus infection, defined as development of S. aureus infection more than 48 hours after ICU admission. S. aureus colonization was present at admission for 1,433 (27.8%) of 5,161 patients (674 [47.0%] with MRSA and 759 [53.0%] with MSSA). An ICU-acquired S. aureus infection developed in 113 (2.19%) patients, of whom 75 (66.4%) had an infection due to MRSA. Risk factors associated with an ICU-acquired S. aureus infection included MRSA colonization at admission (adjusted hazard ratio, 4.70 [95% confidence interval, 3.07-7.21]) and MSSA colonization at admission (adjusted hazard ratio, 2.47 [95% confidence interval, 1.52-4.01]). ICU patients colonized with S. aureus were at greater risk of developing a S. aureus infection in the ICU. Even after adjusting for patient-specific risk factors, MRSA-colonized patients were more likely to develop S. aureus infection, compared with MSSA-colonized or noncolonized patients.

Universal Methicillin-ResistantStaphylococcus aureus(MRSA) Surveillance for Adults at Hospital Admission: An Economic Model and Analysis

Methicillin-resistant Staphylococcus aureus (MRSA) transmission and infections are a continuing problem in hospitals. Although some have recommended universal surveillance for MRSA at hospital admission to identify and to isolate MRSA-colonized patients, there is a need for formal economic studies to determine the cost-effectiveness of such a strategy. We developed a stochastic computer simulation model to determine the potential economic impact of performing MRSA surveillance (ie, single culture of an anterior nares specimen) for all hospital admissions at different MRSA prevalences and basic reproductive rate thresholds from the societal and third party-payor perspectives. Patients with positive surveillance culture results were placed under isolation precautions to prevent transmission by way of respiratory droplets. MRSA-colonized patients who were not isolated could transmit MRSA to other hospital patients. The performance of universal MRSA surveillance was cost-effective (defined as an incremental cost-effectiveness ratio of less than $50,000 per quality-adjusted life-year) when the basic reproductive rate was 0.25 or greater and the prevalence was 1% or greater. In fact, surveillance was the dominant strategy when the basic reproductive rate was 1.5 or greater and the prevalence was 15% or greater, the basic reproductive rate was 2.0 or greater and the prevalence was 10% or greater, and the basic reproductive rate was 2.5 or greater and the prevalence was 5% or greater. Universal MRSA surveillance of adults at hospital admission appears to be cost-effective at a wide range of prevalence and basic reproductive rate values. Individual hospitals and healthcare systems could compare their prevailing conditions (eg, the prevalence of MRSA colonization and MRSA transmission dynamics) with the benchmarks in our model to help determine their optimal local strategies.

Use of a Room Placement Algorithm for Safe Placement of Patients With MRSA and/or VRE Colonization in a Long-term Acute Care (LTAC) Hospital Setting

Use of a Room Placement Algorithm for Safe Placement of Patients With MRSA and/or VRE Colonization in a Long-term Acute Care (LTAC) Hospital Setting

Body site colonization in patients with community-associated methicillin-resistant Staphylococcus aureus and other types of S. aureus skin infections

AbstractEfforts to control spread of community-associated methicillin-resistant Staphylococcus aureus (CA-MRSA) are often based on eradication of colonization. However, the role of nasal and non-nasal colonization in the pathogenesis of these infections remains poorly understood. Patients with acute S. aureus skin and soft tissue infection (SSTI) were prospectively enrolled. Each subject's nasal, axillary, inguinal and rectal areas were swabbed for S. aureus and epidemiological risk factors were surveyed. Among the 117 patients enrolled, there were 99 patients who had an SSTI and for whom data could be analysed. Sixty-five patients had a CA-MRSA SSTI. Among these patients, MRSA colonization in the nares, axilla, inguinal area and rectum was 25, 6, 11 and 13%, respectively, and 37% overall were MRSA colonized. Most (96%) MRSA colonization was detected using nose and inguinal screening alone. Non-nasal colonization was 25% among CA-MRSA patients, but only 6% among patients with CA-methicillin-susceptible S. aureus (MSSA) or healthcare-associated MRSA or MSSA. These findings suggest that colonization patterns in CA-MRSA infection are distinct from those in non-CA-MRSA S. aureus infections. The relatively high prevalence of non-nasal colonization may play a key role in CA-MRSA transmission and acquisition of infection.

Dissemination of Methicillin-resistant Staphylococcus aureus among Healthy Children in Northern Taiwan

Background: We previously reported the incidence of community-associated methicillin-resistant Staphylococcus aureus (CA-MRSA) infections among children in Taiwan was increasing. This study examined the extent of MRSA colonization in the healthy pediatric population existed in parallel with this trend. Method: In this prospective observational study, nasal swabs were obtained from healthy children presenting for child healthcare visits or attending one of seven kindergartens during a 2-year period. A case-control study and molecular typing studies were performed. Results: Of 1195 children, 89 (7.4%) had nares cultures positive for MRSA. Risk factors for MRSA colonization included household contact with a high-risk individual (odds ratio [OR], 8.971; 95% confi dence interval [CI], 2.968-27.117) and recent antibiotic use (OR, 5.997; 95% CI, 3.605-9.976). Staphylococcal cassette chromosome mec (SCCmec) typing showed most community MRSA strains were SCCmec types IV and type V(subscript T). Pulsed-field gel electrophoresis revealed MRSA clones distinct from nosocomial MRSA isolates have disseminated in healthy children, and Panton-Valentine leukocidin genes were present in 15 of 89 MRSA isolates (16.9%). Conclusions: As colonization typically precedes infection, the characteristics of children with MRSA nasal carriage may be useful for distinguishing those who may be at risk of MRSA infection.

Can ‘search and destroy’ reduce nosocomial meticillin-resistant Staphylococcus aureus in an Irish hospital?

In Ireland, the Department of Health and Children recommends admission screening of patients at increased risk of methicillin-resistant Staphylococcus aureus (MRSA), isolation of these patients until proven negative, and eradication of any MRSA identified. These actions form the basis of a programme called 'search and destroy' that has successfully reduced MRSA in Scandinavia. There is, however, very little information published on the use of search and destroy in Ireland. This study was carried out using a quantitative, quasi-experimental design in the form of an interventional cohort study. The effect of reducing the turnaround time for MRSA results (2007) and the introduction of pre-emptive isolation (2008) was examined in a hospital with an established admission screening programme for MRSA. Rates of MRSA infection and colonisation were monitored post-intervention and compared to baseline rates prior to the intervention (2005-2006). Rates of hospital-acquired (nosocomial) MRSA infections and colonisation fell in both 2007 and 2008. However, due to the quasi-experimental design of the study and the low endemic level of MRSA in the hospital, a causal link could not be established.

Active surveillance testing and decontamination strategies in intensive care units to reduce methicillin-resistant Staphylococcus aureus infections

Active surveillance testing (AST) and decontamination strategies (DS) using a topical methicillin-resistant Staphylococcus aureus (MRSA) cleansing agent was introduced in July 2007 in a medical intensive care unit (MICU) and a surgical ICU (SICU) of a tertiary care hospital to reduce the incidence of MRSA infection. Data on ICU admissions between July 1, 2007, and June 30, 2008, was analyzed. All subjects, excluding known MRSA status, had an ICU length of stay (LOS) of more than 24 hours and nasal swabs performed on ICU admission, every 7 days during the ICU stay, and on discharge. MICU and SICU specimens were sent for culture and in-house real-time polymerase chain reaction, respectively. MRSA-colonized (MRSAc) patients were subjected to contact isolation precautions and DS for 5 days or until ICU discharge. Data recorded included demographics, LOS, and antibiotic use. Results were analyzed using SPSS. Control charts were used to determine special cause variation. Of 653 eligible patients admitted to the ICU, 85 (13%) were determined to be MRSAc on ICU admission. A further 15% (52 of 351) were determined to be MRSAc during the ICU stay or at discharge. Thus, AST detected MRSA in at least 137 of the 653 patients (21.0%). In contrast, clinical cultures for MRSA were positive in only 12 patients (1.8%). Compared with noncolonized patients, MRSAc patients at any screening point had a longer pre-ICU LOS (P =.001), received more antibiotics (P = .004), and had a longer ICU LOS (P = .003). Compared with the preintervention period of July 2006 to June 2007, there was no significant reduction in mean MRSA infection incidence rate in both ICUs (3.8 to 3.0 per 1000 patient-days [P = .057] in the SICU and 1.4 to 1.7 per 1000 patient-days in the MICU) following intervention. In ICUs, AST detected 11 times more MRSA than clinical cultures. The lack of reduction in MRSA infection rates in the ICUs does not negate the roles of AST and DS, but does argue for better study design and outcome measures like MRSA transmission incidence, which perhaps would have demonstrated a true benefit of AST and DS.

Reflection paper on MRSA in food-producing and companion animals: epidemiology and control options for human and animal health

The scope of this reflection paper was to review the latest research on the risk of MRSA infection and colonization in animals. Attention focused on occurrence, risk factors for colonization and infection, and human contact hazard for livestock, horses, and companion animals. Whereas the clonal relationship between MRSA strains of CC398 is straightforward in livestock this is less obvious in horses. Small companion animals typically share MRSA strains that seem to exchange with a human reservoir. Management and therapeutic options have been suggested for livestock, horses, companion animals, as well as instructions on safety measures for persons in contact with animals. Conclusions were drawn with emphasis on future research activities, especially to confirm the apparent evolution of the organism and to demonstrate efficiency of control strategies.

The impact of household transmission on duration of outpatient colonization with methicillin-resistantStaphylococcus aureus

We identified eight consecutive patients who presented with a skin or soft tissue infection due to MRSA. Of seven household members of these cases, three were colonized with MRSA. The mean duration of MRSA colonization in index cases was 33 days (range 14-104), while mean duration of colonization in household cases was 54 days (range 12-95). There was a borderline significant association between having a concurrent colonized household member and a longer duration of colonization (mean 44 days vs. 26 days, P=0.08).

Staphylococcus aureus vaccine for orthopedic patients: An economic model and analysis

To evaluate the potential economic value of a Staphylococcus aureus vaccine for pre-operative orthopedic surgery patients, we developed an economic computer simulation model. At MRSA colonization rates as low as 1%, a $50 vaccine was cost-effective [≤$50,000 per quality-adjusted life year (QALY) saved] at vaccine efficacy ≥30%, and a $100 vaccine at vaccine efficacy ≥70%. High MRSA prevalence (≥25%) could justify a vaccine price as high as $1000. Our results suggest that a S. aureus vaccine for the pre-operative orthopedic population would be very cost-effective over a wide range of MRSA prevalence and vaccine efficacies and costs.