Eradication or decolonization of methicillin-resistant Staphylococcus aureus carriage: what are we doing and why are we doing it?
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Biomedical subjects
Publications and source records attributed to Suzanne F Bradley.
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Persistent colonization with Staphylococcus aureus was assessed in 22 nursing home residents. Eighteen residents (82%) remained colonized with the same strain found at baseline; 6 (33%) of 18 residents transiently acquired a new strain. Four residents (18%) acquired a new persistent strain. Residents colonized with methicillin-resistant S. aureus were more likely to acquire a new strain (67%) than were residents colonized with methicillin-susceptible S. aureus (20%) (P=.04).
OBJECTIVES: Evaluate the effect of preadmission functional status on severity of pneumonia, length of hospital stay (LOS), and all-cause 30-day and 1-year mortality of adults aged 60 and older and to understand the effect of pneumonia on short-term functional impairment. DESIGN: Prospective cohort study. SETTING: University hospital. PARTICIPANTS: One hundred twelve patients with radiograph-proven pneumonia (mean age 74.6) were enrolled. MEASUREMENTS: Functional status and comorbidities were assessed using the Functional Autonomy Measurement System (SMAF) and Charlson Comorbidity Index. Clinical information was used to calculate the Pneumonia Prognostic Index (PPI). RESULTS: Eighty-four (75%) patients were functionally independent (FI) before admission, with a SMAF score of 40 or lower. Dementia and aspiration history were higher in the group that was functionally dependent (FD) before admission (P<.001). The FI group had less-severe pneumonia per the PPI and shorter mean LOS+/-standard deviation (5.62+/-0.51 days) than the FD group (11.42+/-2.58, P<.004). The FI group had lower 1-year mortality (19/65, 23%) than the FD group (14/28, 50%), and the difference remained significant after adjusting for Charlson Index and severity of illness (P=.009). All patients lost function after admission, with loss being more pronounced in the FI group (mean change 19.24+/-12.9 vs 4.72+/-6.55, P<.001). CONCLUSION: Older adults who were FI before admission were more likely to present with less-severe pneumonia and have a shorter LOS. In addition, further loss of function was common in these patients. Assessment of function before and during hospitalization should be an integral part of clinical evaluation in all older adults with pneumonia.
OBJECTIVES: We examined the molecular basis of the emergence of mupirocin resistance in a methicillin-resistant Staphylococcus aureus (MRSA) strain colonizing a nursing home resident undergoing mupirocin prophylaxis. PATIENT AND METHODS: A persistent carrier of mupirocin-susceptible MRSA participated in a trial of mupirocin for nasal decolonization among nursing home residents. During prophylaxis a high-level mupirocin-resistant MRSA emerged in the nasal isolates from this patient. S. aureus and coagulase-negative staphylococci were isolated prior to, during and after 14 days of mupirocin treatment. The staphylococcal isolates and their plasmids were examined by molecular genetic methods. RESULTS: All mupirocin-susceptible and -resistant MRSA isolates possessed the same genotype. The patient was also colonized by a single mupirocin-resistant Staphylococcus epidermidis strain. The mupirocin-resistant MRSA and S. epidermidis strains harboured identical plasmids that carried the mupA determinant and genes for conjugative DNA transfer in staphylococci. These plasmids could be transferred in vitro from both clinical isolates to S. aureus RN2677. CONCLUSIONS: The MRSA strain contained a conjugative plasmid expressing mupA that was identical with that found in the S. epidermidis strain which colonized the patient. These findings suggest that transfer of mupA from S. epidermidis to MRSA probably occurred during mupirocin prophylaxis.
CONTEXT: The global significance of infective endocarditis (IE) caused by Staphylococcus aureus is unknown. OBJECTIVES: To document the international emergence of health care-associated S aureus IE and methicillin-resistant S aureus (MRSA) IE and to evaluate regional variation in patients with S aureus IE. DESIGN, SETTING, AND PARTICIPANTS: Prospective observational cohort study set in 39 medical centers in 16 countries. Participants were a population of 1779 patients with definite IE as defined by Duke criteria who were enrolled in the International Collaboration on Endocarditis-Prospective Cohort Study from June 2000 to December 2003. MAIN OUTCOME MEASURE: In-hospital mortality. RESULTS: S aureus was the most common pathogen among the 1779 cases of definite IE in the International Collaboration on Endocarditis Prospective-Cohort Study (558 patients, 31.4%). Health care-associated infection was the most common form of S aureus IE (218 patients, 39.1%), accounting for 25.9% (Australia/New Zealand) to 54.2% (Brazil) of cases. Most patients with health care-associated S aureus IE (131 patients, 60.1%) acquired the infection outside of the hospital. MRSA IE was more common in the United States (37.2%) and Brazil (37.5%) than in Europe/Middle East (23.7%) and Australia/New Zealand (15.5%, P<.001). Persistent bacteremia was independently associated with MRSA IE (odds ratio, 6.2; 95% confidence interval, 2.9-13.2). Patients in the United States were most likely to be hemodialysis dependent, to have diabetes, to have a presumed intravascular device source, to receive vancomycin, to be infected with MRSA, and to have persistent bacteremia (P<.001 for all comparisons). CONCLUSIONS: S aureus is the leading cause of IE in many regions of the world. Characteristics of patients with S aureus IE vary significantly by region. Further studies are required to determine the causes of regional variation.
BACKGROUND: Studies on adherence to infection control policies in nursing homes (NHs) are limited. This pilot study explores the use of various infection control practices and the role of infection control practitioners in southeast Michigan NHs. METHODS: A 43-item self-administered questionnaire and explanatory cover letter were mailed to 105 licensed NHs in southeast Michigan. A second mailing was sent to the nonresponders 4 weeks later. RESULTS: Significant variability existed in adoption of various infection control measures with respect to time spent in infection control activities (50% of facilities having a full-time infection control practitioner), definitions used in monitoring infections, and immunization rates (influenza: range, 0%-100%; mean, 73.2%; pneumococcal: range, 0%-100%; mean, 38.5%). CONCLUSION: Although strides have been made in infection control research in NHs, significant variations exist in implementation of infection control methods and guidelines. Future research should focus on identifying barriers to infection control in NHs.
The clinical presentation of staphylococcal pneumonia is changing. Healthy young people without traditional risk factors for Staphylococcus aureus disease are presenting with severe necrotizing infection and high mortality. The clinical picture is reminiscent of outbreaks of postinfluenzal staphylococcal pneumonia seen in the past century. Most of these staphylococcal strains are methicillin-resistant and are not health care associated. Many strains contain toxins that are likely responsible for the severity of illness seen. Panton-Valentine leukocidin has rarely been identified in S. aureus until recently. It appears that the genetic element for methicillin resistance has been introduced into multiple highly virulent methicillin-susceptible strains with great potential for further spread. Early recognition and treatment of possible community-acquired methicillin-resistant S. aureus (CA-MRSA) is essential. It is equally important to attain microbiological confirmation of the diagnosis for optimal treatment and to initiate appropriate infection control procedures.
Limited data identify the risk factors for infection with Enterobacteriaceae resistant to third-generation cephalosporins among residents of long-term-care facilities. Using a nested case-control study design, nursing home residents with clinical isolates of Enterobacteriaceae resistant to third-generation cephalosporins were compared to residents with isolates of Enterobacteriaceae susceptible to third-generation cephalosporins. Data were collected on antimicrobial drug exposure 10 weeks before detection of the isolates, facility-level demographics, hygiene facilities, and staffing levels. Logistic regression models were built to adjust for confounding variables. Twenty-seven case-residents were identified and compared to 85 controls. Exposure to any cephalosporin (adjusted odds ratio [OR] 4.0, 95% confidence interval [CI] 1.2 to 13.6) and log percentage of residents using gastrostomy tubes within the nursing home (adjusted OR 3.9, 95% CI 1.3 to 12.0) were associated with having a clinical isolate resistant to third-generation cephalosporins.
Mupirocin has been used in nursing homes to prevent the spread of methicillin-resistant Staphylococcus aureus (MRSA), despite the lack of controlled trials. In this double-blind, randomized study, the efficacy of intranasal mupirocin ointment versus that of placebo in reducing colonization and preventing infection was assessed among persistent carriers of S. aureus. Twice-daily treatment was given for 2 weeks, with a follow-up period of 6 months. Staphylococcal colonization rates were similar between residents at the Ann Arbor Veterans Affairs (VA) Extended Care Center, Michigan (33%), and residents at a community-based long-term care facility in Ann Arbor (36%), although those at the VA Center carried MRSA more often (58% vs. 35%; P=.017). After treatment, mupirocin had eradicated colonization in 93% of residents, whereas 85% of residents who received placebo remained colonized (P<.001). At day 90 after study entry, 61% of the residents in the mupirocin group remained decolonized. Four patients did not respond to mupirocin therapy; 3 of the 4 had mupirocin-resistant S. aureus strains. Thirteen (86%) of 14 residents who became recolonized had the same pretherapy strain; no strain recovered during relapse was resistant to mupirocin. A trend toward reduction in infections was seen with mupirocin treatment.
We assessed whether trivalent live, cold-adapted influenza virus (CAIV-T) vaccine provides added protection when co-administered with trivalent inactivated influenza virus vaccine (TVV) in patients with chronic obstructive pulmonary disease (COPD). Subjects (N=2215) were randomly assigned to receive either TVV intramuscularly (IM) and CAIV-T intranasally (TC), or TVV and placebo (TP). The vaccines were well-tolerated. Efficacy of TC compared to TP was not statistically significant and was 0.16 for any influenza virus strain (95% confidence limit (CL): -0.22, 0.43), 0.26 for A (H3N2) virus (95% CL: -0.17, 0.53), and -0.05 for type B virus (95% CL: -1.13, 0.48). However, there was a possible advantage for TC over TP in reducing respiratory consequences of an influenza season measured by pulmonary function and symptoms at end of study.
The authors prospectively collected data on exposure to antimicrobial agents and susceptibility patterns among all clinical isolates of bacteria taken from 9,156 residents of 50 nursing homes in Canada and the United States in 1998-1999. Exposure to antimicrobial agents was measured during the 10 weeks prior to detection of targeted resistant bacteria in residents and compared with antibiotic exposure during a 10-week interval in individuals with sensitive organisms. These main effects were adjusted for infection-control and staffing covariates using multiple logistic regression modeling. Increased staffing of nursing homes with registered nurses (adjusted odds ratio (OR) = 0.79 (95% confidence interval (CI): 0.72, 0.87) per registered nurse per 100 resident-days) and use of antibacterial soap (adjusted OR = 0.40, 95% CI: 0.18, 0.90) were associated with reduced risk of methicillin-resistant Staphylococcus aureus in nursing home residents. An increase in the number of hand-washing sinks per 100 residents was shown to reduce the risk of trimethoprim-sulfamethoxazole (TMP/SMX)-resistant Enterobacteriaceae (adjusted OR = 0.94, 95% CI: 0.90, 0.98). Exposure to TMP-SMX and exposure to fluoroquinolones were significant risk factors for isolation of TMP-SMX-resistant Enterobacteriaciae (adjusted OR = 1.14, 95% CI: 1.06, 1.22) and fluoroquinolone-resistant Enterobacteriaciae (adjusted OR = 1.08, 95% CI: 1.04, 1.11), respectively. These findings suggest that increased staffing, more hand-washing sinks, and use of antimicrobial soap may reduce resistance to antimicrobial agents in long-term care facilities.
Eleven patients developed deep sternal wound infections due to Candida albicans after undergoing coronary artery bypass grafting (CABG) and were assessed. Six had sternal osteomyelitis, 1 had osteomyelitis and mediastinitis, and 4 had deep wound infections that probably involved bone. Seven patients experienced onset of infection within 28 days of CABG, but 4 experienced onset 48-150 days after CABG. Infections were characterized by a chronic, indolent course requiring prolonged treatment with an antifungal agent. Delay in initiating antifungal therapy was common. All patients were treated with fluconazole, and 1 also received amphotericin B. Six patients underwent incision and drainage, with or without wire removal, and 3 underwent sternectomy with placement of a muscle flap. Of 10 patients for whom follow-up data were available, 7 were cured after initial therapy (median duration of treatment, 6 months), and 3 experienced a relapse and required a second course of fluconazole.
Antimicrobial agents are among the most frequently prescribed medications in long-term-care facilities (LTCFs). Therefore, it is not surprising that Clostridium difficile colonization and C. difficile-associated diarrhea (CDAD) occur commonly in elderly LTCF residents. C. difficile has been identified as the most common cause of non-epidemic acute diarrheal illness in nursing homes, and outbreaks of CDAD in LTCFs have also been recognized. This position paper reviews the epidemiology and clinical features of CDAD in elderly residents of LTCFs and, using available evidence, provides recommendations for the management of C. difficile in this setting.
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Asymptomatic colonization with methicillin-resistant Staphylococcus aureus (MRSA) is common in long-term care facilities, but the burden of symptomatic infection appears to be low. Patients known to be MRSA carriers should not be refused admission, and routine cultures to identify carriers are not warranted. In the absence of symptomatic MRSA, no measures beyond routine infection control and standard precautions are necessary. Increased rates of infection should prompt investigation of a potential outbreak and initiation of more drastic infection-control measures. During an outbreak, both infected and colonized residents should be isolated until transmission has been halted. Using short-term nasal application of mupirocin ointment for MRSA-colonized residents and staff implicated in the outbreak may help break the chain of transmission.
The prevalence of infection with Staphylococcus aureus among older adults is unknown, but clinical syndromes caused by this organism are common. Bacteremia, pneumonia, endocarditis, and bone and joint infections are encountered with relative frequency in this population, and the clinical presentation may be atypical. Underlying disease and functional debility, rather than age itself, predispose the older adult to staphylococcal carriage and infection. Infections with methicillin-resistant strains of S. aureus are acquired primarily in hospital, rather than in nursing homes or in the community. Lack of clinical suspicion for S. aureus infection and delays in appropriate therapy can be fatal. Staphylococcal infection should be considered for an older adult with risk factors for staphylococcal carriage, comorbid illness, debility, and history of recent hospitalization or nursing home stay. Choices regarding empirical therapy should be made on the basis of knowledge of local antibiotic susceptibility patterns.