[Show abstract][Hide abstract] ABSTRACT: HIV patients are at increased risk of development of infections and infection-associated poor health outcomes. We aimed to 1) assess the prevalence of USA300 community-associated methicillin-resistant Staphylococcus aureus (CA-MRSA) among HIV-infected patients with S. aureus bloodstream infections and. 2) determine risk factors for infective endocarditis and in-hospital mortality among patients in this population.
All adult HIV-infected patients with documented S. aureus bacteremia admitted to the University of Maryland Medical Center between January 1, 2003 and December 31, 2005 were included. CA-MRSA was defined as a USA 300 MRSA isolate with the MBQBLO spa-type motif and positive for both the arginine catabolic mobile element and Panton-Valentin Leukocidin. Risk factors for S. aureus-associated infective endocarditis and mortality were determined using logistic regression to calculate odds ratios (OR) and 95% confidence intervals (CI). Potential risk factors included demographic variables, comorbid illnesses, and intravenous drug use.
Among 131 episodes of S. aureus bacteremia, 85 (66%) were MRSA of which 47 (54%) were CA-MRSA. Sixty-three patients (48%) developed endocarditis and 10 patients (8%) died in the hospital on the index admission Patients with CA-MRSA were significantly more likely to develop endocarditis (OR = 2.73, 95% CI = 1.30, 5.71). No other variables including comorbid conditions, current receipt of antiretroviral therapy, pre-culture severity of illness, or CD4 count were significantly associated with endocarditis and none were associated with in-hospital mortality.
CA-MRSA was significantly associated with an increased incidence of endocarditis in this cohort of HIV patients with MRSA bacteremia. In populations such as these, in which the prevalence of intravenous drug use and probability of endocarditis are both high, efforts must be made for early detection, which may improve treatment outcomes.
Preview · Article · Oct 2011 · BMC Infectious Diseases
[Show abstract][Hide abstract] ABSTRACT: To examine the pathogenesis of USA300 MRSA infection in long-term care residents, we performed a retrospective cohort study of 1691 adult residents of two extended-care facilities from 2003 to 2007 to assess whether the risk of subsequent MRSA infection is higher in USA300 MRSA-colonized residents compared to non-colonized residents or non-USA300 MRSA colonized residents. Six per cent of residents were colonized with USA300 MRSA; 12% of residents were colonized with non-USA300 MRSA; and 101 residents developed MRSA infection. The risk of infection was twofold higher in residents colonized with USA300 MRSA compared to residents not colonized with MRSA [adjusted hazard ratio 2·3, 95% confidence interval (CI) 1·1-4·5]. The risk of infection in USA300 MRSA-colonized residents was similar to USA300 MRSA non-colonized residents (relative risk 1·1, 95% CI 0·5-2·3). Our findings show that colonization with USA300 MRSA increases the risk of MRSA infection suggesting a similar pathogenesis.
No preview · Article · Jul 2011 · Epidemiology and Infection
[Show abstract][Hide abstract] ABSTRACT: To assess risk factors for methicillin-resistant Staphylococcus aureus (MRSA) acquisition among extended care residents focusing on level of care (residential vs rehabilitation) and room placement with an MRSA-positive resident.
Prospective cohort study.
Extended care units at 2 healthcare systems in Maryland.
Four hundred forty-three residents with no history of MRSA and negative MRSA surveillance cultures of the anterior nares and areas of skin breakdown at enrollment.
Follow-up cultures were collected every 4 weeks and/or at discharge for a period of 12 weeks. Study data were collected by a research nurse from the medical staff and the electronic medical records. Cox proportional hazards modeling was used to calculate adjusted hazards ratios (aHRs) and 95% confidence intervals (CIs).
Residents in rehabilitation care had 4-fold higher risk of MRSA acquisition compared with residents in residential care (hazard ratio [HR], 4. [95% CI, 2.2-8.8]). Being bedbound was significantly associated with MRSA acquisition in both populations (residential care, aHR, 4.3 [95% CI, 1.5-12.2]; rehabilitation care, aHR, 4.8 [95% CI, 1.2-18.7]). Having an MRSA-positive roommate was not significantly associated with acquisition in either population (residential care, aHR, 1.4 [95% CI, 0.5-3.9]; rehabilitation care, aHR, 0.5 [95% CI, 0.1-2.2]); based on concordant spa typing, only 2 of 8 residents who acquired MRSA and had room placement with an MRSA-positive resident acquired their MRSA isolate from their roommate.
Residents in rehabilitation care appear at higher risk and have different risk factors for MRSA acquisition compared to those in residential care.
No preview · Article · Mar 2011 · Infection Control and Hospital Epidemiology
[Show abstract][Hide abstract] ABSTRACT: The anterior nares are the most sensitive single site for detecting methicillin-resistant Staphylococcus aureus (MRSA) colonization. Colonization patterns of USA300 MRSA colonization are unknown.
To assess whether residents of extended care facilities who are colonized with USA300 MRSA have different nares or skin colonization findings, compared with residents who are colonized with non-USA300 MRSA strains.
The study population included residents of 5 extended care units in 3 separate facilities who had a recent history of MRSA colonization. Specimens were obtained weekly for surveillance cultures from the anterior nares, perineum, axilla, and skin breakdown (if present) for 3 weeks. MRSA isolates were categorized as USA300 MRSA or non-USA300 MRSA.
Of the 193 residents who tested positive for MRSA, 165 were colonized in the anterior nares, and 119 were colonized on their skin. Eighty-four percent of USA300 MRSA-colonized residents had anterior nares colonization, compared with 86% of residents colonized with non-USA300 MRSA (P= .80). Sixty-six percent of USA300 MRSA-colonized residents were colonized on the skin, compared with 59% of residents colonized with non-USA300 MRSA (P= .30).
Colonization patterns of USA300 MRSA and non-USA300 MRSA are similar in residents of extended care facilities. Anterior nares cultures will detect most--but not all--people who are colonized with MRSA, regardless of whether it is USA300 or non-USA300 MRSA.
Full-text · Article · Mar 2009 · Infection Control and Hospital Epidemiology
[Show abstract][Hide abstract] ABSTRACT: Background: S. aureus can survive for months on environmental surfaces. This may serve as an indirect source of transmission to uninfected individuals and as a marker of the ability to transmit to others. The objective of this study was to estimate the association between the level of MRSA colonization in MRSA (+) adults and MRSA transmission to the environment. Methods:
We conducted a cohort study of residents with a recent history of MRSA in 3 extended care facilities over 4 years. In a series of 12 week study cycles, we cultured the anterior nares and perineum every week. We cultured the largest area of skin breakdown every 4 weeks. Environmental cultures of the floor by their bedside were obtained every 4 weeks. Residents who were culture positive and present for at least 4 weeks were included. We collected demographic and clinical characteristics including uncontrolled secretions (e.g. diarrhea). We calculated a level of nares colonization as # of MRSA (+) nares cultures / # of nares cultures collected. Results: 204 residents met our eligibility criteria. The mean age was 56 years and 86% were men. 51% were in residential care; 29%, long term rehabilitation and 20%, short term rehabilitation or post-acute care. 47% had a positive floor culture. Percentage of weekly nares culture positive (median 71% vs. 50%, p=0.001) and diarrhea (16% vs. 7%, p=0.06) were associated with being floor positive. Perineal culture positive (22% vs. 27%, p=0.55) or skin breakdown positive (34% vs. 27%, p=0.24) was not associated with being floor positive.
Conclusions: High level colonization as defined by percentage of weekly nares cultures positive and diarrhea are associated with transmission to the environment. Further investigation is needed to determine whether these factors are associated with transmission to other residents.
[Show abstract][Hide abstract] ABSTRACT: To estimate the prevalence of and determine risk factors for Staphylococcus aureus colonization of the perineum.
Cross-sectional study with follow-up of up to 1 year.
Multiple outpatient sites.
Eighty-four community-dwelling adults with spinal cord dysfunction (SCD).
Colonization of perineum with S. aureus.
Overall, 24% of the study cohort carried S. aureus on their perineal skin at enrollment, with 16% having methicillin-susceptible S. aureus and 10% having methicillin-resistant S. aureus (MRSA). Most perineal carriers were also colonized in the anterior nares. Participants with trauma as the cause of their SCD were more likely to be colonized with S. aureus than participants with SCD caused by multiple sclerosis or other causes (relative risk [RR], 2.8; 95% confidence interval [CI], 1.2-6.6; P=.01). Participants with pelvic decubiti were more likely to be colonized with S. aureus than participants without pelvic decubiti (RR=4.3; 95% CI, 2.4-7.7; P<.001). The recent use of any antibiotic was not associated with an increased risk of colonization with S. aureus (RR=1.5; 95% CI, 0.7-3.3; P=.31); however, recent fluoroquinolone use was significantly associated with perineal colonization (RR=2.8; 95% CI, 1.4-5.8; P=.02). Of the 8 participants with MRSA colonization, only 2 (25%) had a history of MRSA colonization.
S. aureus colonization of the perineum is common in this outpatient population of people with SCD. The use of fluoroquinolones was associated with S. aureus colonization. Colonization with MRSA without a history of MRSA was common.
No preview · Article · Aug 2007 · Archives of Physical Medicine and Rehabilitation
[Show abstract][Hide abstract] ABSTRACT: Until recently, methicillin-resistant Staphylococcus aureus (MRSA) has caused predominantly healthcare-associated infections. We studied MRSA infections and overall skin and soft tissue infections (SSTIs) in outpatients receiving care at the Baltimore Veterans Affairs Medical Center Emergency Care Service during 2001-2005. We found an increase in MRSA infections, from 0.2 to 5.9 per 1,000 visits (p < 0.01); most were community-associated SSTIs. Molecular typing showed that > 80% of MRSA infections were caused by USA300. In addition, SSTI visits increased from 20 to 61 per 1,000 visits (p < 0.01). The proportion of SSTI cultures that yielded MRSA increased from 4% to 42% (p < 0.01), while the proportion that yielded methicillin-sensitive S. aureus remained the same (10% to 13%, p = 0.5). The increase in community-associated MRSA infections and the overall increase in SSTIs in our population suggest that USA300 is becoming more virulent and has a greater propensity to cause SSTIs.
Preview · Article · Aug 2007 · Emerging infectious diseases
[Show abstract][Hide abstract] ABSTRACT: Extended-spectrum beta-lactamase (ESBL)-producing Escherichia coli is an emerging pathogen. The causal role of antibiotic selective pressure versus patient-to-patient transmission has not been assessed. The objective of this study was to quantify the amount of patient-to-patient transmission among patients who acquire an ESBL-producing E coli infection using perianal surveillance cultures in an intensive care unit (ICU) population.
A prospective cohort of patients admitted between September 1, 2001, and September 1, 2004, to the medical and surgical ICUs at a tertiary care hospital was studied. Patients had perianal cultures on admission, weekly, and upon discharge. Strain typing by pulsed-field gel electrophoresis (PFGE) and epidemiologic criteria were used to quantify the amount of patient-to-patient transmission.
There were 1806 patients admitted to the ICUs. There were 74 patients who had ESBL-producing E coli on admission to the ICU and 23 patients who acquired ESBL-producing E coli. Among these 23 patients, there were 14 PFGE types, and 3 (13%) patient acquisitions were defined as patient-to-patient transmission by similar PFGE type and overlapping time in the hospital.
Our data suggest that patient-to-patient transmission is not an important cause of the acquisition of ESBL-producing E coli colonization in the ICU setting.
No preview · Article · Apr 2007 · American Journal of Infection Control
[Show abstract][Hide abstract] ABSTRACT: To quantify the clinical impact of methicillin-resistance in Staphylococcus aureus causing infection complicated by bacteremia in adult patients, while controlling for the severity of patients' underlying illnesses.
Retrospective cohort study from October 1, 1995, through December 31, 2003.
A total of 438 patients with S. aureus infection complicated by bacteremia from a single Veterans Affairs healthcare system.
We found that 193 (44%) of the 438 patients had methicillin-resistant S. aureus (MRSA) infection and 114 (26%) died of causes attributable to S. aureus infection within 90 days after the infection was identified. Patients with MRSA infection had a higher mortality risk, compared with patients with methicillin-susceptible S. aureus (MSSA) infections (relative risk, 1.7 [95% confidence interval, 1.3-2.4]; P<.01), except for patients with pneumonia (relative risk, 0.7 [95% confidence interval, 0.4-1.3]). Patients with MRSA infections were significantly older (P<.01), had more underlying diseases (P=.02), and were more likely to have severe sepsis in response to their infection (P<.01) compared with patients with MSSA bacteremia. Patients who died within 90 days after S. aureus infection was identified were significantly older (P<.01) and more likely to have severe sepsis (P<.01) and pneumonia (P=.01), compared with patients who survived. After adjusting for age as a confounder, comorbidities, and pneumonia as an effect modifier, S. aureus infection-related mortality remained significantly higher in patients with MRSA infection than in those with MSSA infection, among those without pneumonia (hazard ratio, 1.8 [95% confidence interval, 1.2-3.0]); P<.01.
The results of this study suggest that patients with MRSA infections other than pneumonia have a higher mortality risk than patients with MSSA infections other than pneumonia, independent of the severity of patients' underlying illnesses.
Full-text · Article · Mar 2007 · Infection Control and Hospital Epidemiology