Comparison of community- and health care-associated methicillin-resistant Staphylococcus aureus infection.
TL;DR: It is suggested that most community-associated MRSA strains did not originate in health care settings, and that their microbiological features may have contributed to their emergence in the community.
Abstract: Context Methicillin-resistant Staphylococcus aureus (MRSA) has traditionally been considered a health care–associated pathogen in patients with established risk factors. However, MRSA has emerged in patients without established risk factors (community-associated MRSA). Objective To characterize epidemiological and microbiological characteristics of community-associated MRSA cases compared with health care–associated MRSA cases. Design, Setting, and Patients Prospective cohort study of patients with MRSA infection identified at 12 Minnesota laboratory facilities from January 1 through December 31, 2000, comparing community-associated (median age, 23 years) with health care–associated (median age, 68 years) MRSA cases. Main Outcome Measures Clinical infections associated with either communityassociated or health care–associated MRSA, microbiological characteristics of the MRSA isolates including susceptibility testing, pulsed-field gel electrophoresis, and staphylococcal exotoxin gene testing. Results Of 1100 MRSA infections, 131 (12%) were community-associated and 937 (85%) were health care–associated; 32 (3%) could not be classified due to lack of information. Skin and soft tissue infections were more common among communityassociated cases (75%) than among health care–associated cases (37%) (odds ratio [OR], 4.25; 95% confidence interval [CI], 2.97-5.90). Although communityassociated MRSA isolates were more likely to be susceptible to 4 antimicrobial classes (adjusted OR, 2.44; 95% CI, 1.35-3.86), most community-associated infections were initially treated with antimicrobials to which the isolate was nonsusceptible. Communityassociated isolates were also more likely to belong to 1 of 2 pulsed-field gel electrophoresis clonal groups in both univariate and multivariate analysis. Communityassociated isolates typically possessed different exotoxin gene profiles (eg, Panton Valentine leukocidin genes) compared with health care–associated isolates. Conclusions Community-associated and health care–associated MRSA cases differ demographically and clinically, and their respective isolates are microbiologically distinct. This suggests that most community-associated MRSA strains did not originate in health care settings, and that their microbiological features may have contributed to their emergence in the community. Clinicians should be aware that therapy with -lactam antimicrobials can no longer be relied on as the sole empiric therapy for severely ill outpatients whose infections may be staphylococcal in origin.
Citations
More filters
TL;DR: Invasive MRSA infection affects certain populations disproportionately and is a major public health problem primarily related to health care but no longer confined to intensive care units, acute care hospitals, or any health care institution.
Abstract: ContextAs the epidemiology of infections with methicillin-resistant Staphylococcus aureus (MRSA) changes, accurate information on the scope and magnitude of MRSA infections in the US population is needed.ObjectivesTo describe the incidence and distribution of invasive MRSA disease in 9 US communities and to estimate the burden of invasive MRSA infections in the United States in 2005.Design and SettingActive, population-based surveillance for invasive MRSA in 9 sites participating in the Active Bacterial Core surveillance (ABCs)/Emerging Infections Program Network from July 2004 through December 2005. Reports of MRSA were investigated and classified as either health care–associated (either hospital-onset or community-onset) or community-associated (patients without established health care risk factors for MRSA).Main Outcome MeasuresIncidence rates and estimated number of invasive MRSA infections and in-hospital deaths among patients with MRSA in the United States in 2005; interval estimates of incidence excluding 1 site that appeared to be an outlier with the highest incidence; molecular characterization of infecting strains.ResultsThere were 8987 observed cases of invasive MRSA reported during the surveillance period. Most MRSA infections were health care–associated: 5250 (58.4%) were community-onset infections, 2389 (26.6%) were hospital-onset infections; 1234 (13.7%) were community-associated infections, and 114 (1.3%) could not be classified. In 2005, the standardized incidence rate of invasive MRSA was 31.8 per 100 000 (interval estimate, 24.4-35.2). Incidence rates were highest among persons 65 years and older (127.7 per 100 000; interval estimate, 92.6-156.9), blacks (66.5 per 100 000; interval estimate, 43.5-63.1), and males (37.5 per 100 000; interval estimate, 26.8-39.5). There were 1598 in-hospital deaths among patients with MRSA infection during the surveillance period. In 2005, the standardized mortality rate was 6.3 per 100 000 (interval estimate, 3.3-7.5). Molecular testing identified strains historically associated with community-associated disease outbreaks recovered from cultures in both hospital-onset and community-onset health care–associated infections in all surveillance areas.ConclusionsInvasive MRSA infection affects certain populations disproportionately. It is a major public health problem primarily related to health care but no longer confined to intensive care units, acute care hospitals, or any health care institution.
3,803 citations
Cites background from "Comparison of community- and health..."
...Studies of the emergence of community-associated MRSA disease over the past decade determined that isolates causing community-associated and health care–associated MRSA infections were distinct.(10) Isolates from the community were susceptible to most non– -lactam antimicrobial agents,(10) carried staphylococcal cassette chromosome type IV,(14) and frequently encoded the dermonecrotic cytotoxin known as Panton-Valentine leukocidin....
[...]
...17 In contrast, strains most frequently associated with MRSA infections in health care settings were USA100, USA200, and less often, USA50018; these tradit ional ly have been mult idrugresistant and have carried staphylococcal cassette chromosome type II.10 In hospitalized patients, MRSA has been a problem since the 1960s19; approximately 20% of bloodstream infections in the hospital setting have been caused by S aureus.20 The proportion of hospital-onset S aureus infections that were methicillin-resistant reached 64.4% in US intensive care units in 2003.21 In the hospital, MRSA infections are associated with greater lengths of stay, higher mortality,22 and increased costs.23,24 Although more recently there has been increased surveillance activity for invasive MRSA infections in the community, surveillance for MRSA bloodstream infections in the United States traditionally has been limited to hospital-onset (ie, nosocomial) disease.20,21 As the epidemiology of MRSA disease changes, including both community- and health care–associated disease, accurate information on the scope and magnitude of the burden of MRSA disease in the US population is needed to set priorities for prevention and control....
[...]
...In contrast, strains most frequently associated with MRSA infections in health care settings were USA100, USA200, and less often, USA500(18); these tradit ional ly have been mult idrugresistant and have carried staphylococcal cassette chromosome type II.(10) In hospitalized patients, MRSA has been a problem since the 1960s(19); approximately 20% of bloodstream infections in the hospital setting have been caused by S aureus....
[...]
TL;DR: These guidelines discuss the management of a variety of clinical syndromes associated with MRSA disease, including skin and soft tissue infections (SSTI), bacteremia and endocarditis, pneumonia, bone and joint infections, and central nervous system infections.
Abstract: Evidence-based guidelines for the management of patients with methicillin-resistant Staphylococcus aureus (MRSA) infections were prepared by an Expert Panel of the Infectious Diseases Society of America (IDSA). The guidelines are intended for use by health care providers who care for adult and pediatric patients with MRSA infections. The guidelines discuss the management of a variety of clinical syndromes associated with MRSA disease, including skin and soft tissue infections (SSTI), bacteremia and endocarditis, pneumonia, bone and joint infections, and central nervous system (CNS) infections. Recommendations are provided regarding vancomycin dosing and monitoring, management of infections due to MRSA strains with reduced susceptibility to vancomycin, and vancomycin treatment failures.
3,370 citations
Cites background from "Comparison of community- and health..."
...However, because 95%–100% of CA-MRSA strains are susceptible in vitro [81, 82], it has become an important option for the outpatient treatment of SSTI [83–85]....
[...]
TL;DR: MRSA is the most common identifiable cause of skin and soft-tissue infections among patients presenting to emergency departments in 11 U.S. cities and clinicians should consider obtaining cultures and modifying empirical therapy to provide MRSA coverage.
Abstract: BACKGROUND Methicillin-resistant Staphylococcus aureus (MRSA) is increasingly recognized in infections among persons in the community without established risk factors for MRSA. METHODS We enrolled adult patients with acute, purulent skin and soft-tissue infections presenting to 11 university-affiliated emergency departments during the month of August 2004. Cultures were obtained, and clinical information was collected. Available S. aureus isolates were characterized by antimicrobial-susceptibility testing, pulsed-field gel electrophoresis, and detection of toxin genes. On MRSA isolates, we performed typing of the staphylococcal cassette chromosome mec (SCCmec), the genetic element that carries the mecA gene encoding methicillin resistance. RESULTS S. aureus was isolated from 320 of 422 patients with skin and soft-tissue infections (76 percent). The prevalence of MRSA was 59 percent overall and ranged from 15 to 74 percent. Pulsed-field type USA300 isolates accounted for 97 percent of MRSA isolates; 74 percent of these were a single strain (USA300-0114). SCCmec type IV and the Panton-Valentine leukocidin toxin gene were detected in 98 percent of MRSA isolates. Other toxin genes were detected rarely. Among the MRSA isolates, 95 percent were susceptible to clindamycin, 6 percent to erythromycin, 60 percent to fluoroquinolones, 100 percent to rifampin and trimethoprim-sulfamethoxazole, and 92 percent to tetracycline. Antibiotic therapy was not concordant with the results of susceptibility testing in 100 of 175 patients with MRSA infection who received antibiotics (57 percent). Among methicillin-susceptible S. aureus isolates, 31 percent were USA300 and 42 percent contained pvl genes. CONCLUSIONS MRSA is the most common identifiable cause of skin and soft-tissue infections among patients presenting to emergency departments in 11 U.S. cities. When antimicrobial therapy is indicated for the treatment of skin and soft-tissue infections, clinicians should consider obtaining cultures and modifying empirical therapy to provide MRSA coverage.
2,096 citations
TL;DR: In the early 21st century, IE is more often an acute disease, characterized by a high rate of S aureus infection, and Mortality remains relatively high.
Abstract: (32.3%), and intracardiac abscess (14.4%). Surgical therapy was common (48.2%), and in-hospital mortality remained high (17.7%). Prosthetic valve involvement (odds ratio, 1.47; 95% confidence interval, 1.131.90), increasing age (1.30; 1.17-1.46 per 10-year interval), pulmonary edema (1.79; 1.39-2.30), S aureus infection (1.54; 1.14-2.08), coagulase-negative staphylococcal infection (1.50; 1.07-2.10), mitral valve vegetation (1.34; 1.06-1.68), and paravalvular complications (2.25; 1.643.09) were associated with an increased risk of inhospital death, whereas viridans streptococcal infection (0.52; 0.33-0.81) and surgery (0.61; 0.44-0.83) were associated with a decreased risk. Conclusions: In the early 21st century, IE is more often an acute disease, characterized by a high rate ofS aureus infection. Mortality remains relatively high.
1,816 citations
Additional excerpts
...003 Invasive procedure within 60 d 690/2581 (27) 392/1463 (27) 162/508 (32) 64/247 (26) 289/1145 (25) 175/681 (26) ....
[...]
...Staphylococcus aureus 869 (31) 487 (31) 256 (43) 43 (17) 339 (28) 231 (32) ....
[...]
...001 Native valve predisposition 884/2761 (32) 538/1547 (35) 147/596 (25) 93/252 (37) 370/1201 (31) 274/712 (38) ....
[...]
...002 CHF 876/2713 (32) 414/1527 (27) 207/591 (35) 97/249 (39) 383/1162 (33) 189/711 (27) ....
[...]
TL;DR: This review details the epidemiology of CA-MRSA strains and the clinical spectrum of infectious syndromes associated with them that ranges from a commensal state to severe, overwhelming infection and addresses the therapy of these infections and strategies for their prevention.
Abstract: Summary: Staphylococcus aureus is an important cause of skin and soft-tissue infections (SSTIs), endovascular infections, pneumonia, septic arthritis, endocarditis, osteomyelitis, foreign-body infections, and sepsis. Methicillin-resistant S. aureus (MRSA) isolates were once confined largely to hospitals, other health care environments, and patients frequenting these facilities. Since the mid-1990s, however, there has been an explosion in the number of MRSA infections reported in populations lacking risk factors for exposure to the health care system. This increase in the incidence of MRSA infection has been associated with the recognition of new MRSA clones known as community-associated MRSA (CA-MRSA). CA-MRSA strains differ from the older, health care-associated MRSA strains; they infect a different group of patients, they cause different clinical syndromes, they differ in antimicrobial susceptibility patterns, they spread rapidly among healthy people in the community, and they frequently cause infections in health care environments as well. This review details what is known about the epidemiology of CA-MRSA strains and the clinical spectrum of infectious syndromes associated with them that ranges from a commensal state to severe, overwhelming infection. It also addresses the therapy of these infections and strategies for their prevention.
1,807 citations
Cites background from "Comparison of community- and health..."
...PVL , but only 4% of HA-MRSA isolates were PVL (654)....
[...]
...Thus, MRSA in the community has a complex epidemiology arising from the circulation of “escaped,” or so-called feral, HAMRSA strains in the general population (115, 117, 154, 437, 529, 852) and the newly recognized CA-MRSA strains (654)....
[...]
...This case definition was initially used to demonstrate that MRSA infections were occurring among healthy people in the community without health care exposure (306, 654)....
[...]
...CA-MRSA isolates have typically been susceptible to most non- -lactam antimicrobial drugs (383, 654), including several orally available agents....
[...]
References
More filters
01 Jan 2000
16,612 citations
TL;DR: This research presents a novel, scalable and scalable approach that allows for real-time assessment of the severity of the infection and its impact on patients’ health.
Abstract: FRED C. TENOVER,* ROBERT D. ARBEIT, RICHARD V. GOERING, PATRICIA A. MICKELSEN, BARBARA E. MURRAY, DAVID H. PERSING, AND BALA SWAMINATHAN National Center for Infectious Diseases, Centers for Disease Control and Prevention, Atlanta, Georgia 30333; Veterans Affairs Medical Center, Boston, Massachusetts 02130; Creighton University, Omaha, Nebraska 68178; Stanford University Medical Center, Stanford, California 94305; University of Texas Medical School, Houston, Texas 77030; and Mayo Clinic, Rochester, Minnesota 55905
7,784 citations
TL;DR: In an elegant series of clinical observations and laboratory studies published in 1880 and 1882, Ogston described staphylococcal disease and its role in sepsis and abscess formation.
Abstract: Micrococcus, which, when limited in its extent and activity, causes acute suppurative inflammation (phlegmon), produces, when more extensive and intense in its action on the human system, the most virulent forms of septicaemia and pyaemia.1 In an elegant series of clinical observations and laboratory studies published in 1880 and 1882, Ogston described staphylococcal disease and its role in sepsis and abscess formation.1,2 More than 100 years later, Staphylococcus aureus remains a versatile and dangerous pathogen in humans. The frequencies of both community-acquired and hospital-acquired staphylococcal infections have increased steadily, with little change in overall mortality. Treatment of these infections . . .
5,550 citations
TL;DR: Panton-Valentine leukocidin genes were detected in 93% of strains associated with furunculosis and in 85% of those associated with severe necrotic hemorrhagic pneumonia (all community-acquired), and it appears that PVL is mainly associated with nec rotic lesions involving the skin or mucosa.
Abstract: Panton-Valentine leukocidin (PVL) is a cytotoxin that causes leukocyte destruction and tissue necrosis. It is produced by fewer than 5% of Staphylococcus aureus strains. A collection of 172 S. aureus strains were screened for PVL genes by polymerase chain reaction amplification. PVL genes were detected in 93% of strains associated with furunculosis and in 85% of those associated with severe necrotic hemorrhagic pneumonia (all community-acquired). They were detected in 55% of cellulitis strains, 50% of cutaneous abscess strains, 23% of osteomyelitis strains, and 13% of finger-pulp-infection strains. PVL genes were not detected in strains responsible for other infections, such as infective endocarditis, mediastinitis, hospital-acquired pneumonia, urinary tract infection, and enterocolitis, or in those associated with toxic-shock syndrome. It thus appears that PVL is mainly associated with necrotic lesions involving the skin or mucosa.
2,463 citations
"Comparison of community- and health..." refers background in this paper
...In Europe, Panton Valentine leukocidin genes are associated with community-associated staphylococcal skin infections and necrotizing pneumonia.(26,34,35) Similarly, in our study, most community-associated MRSA isolates that had Panton Valentine leukocidin genes were associated with skin and soft tissue infections....
[...]
TL;DR: Analysis of CA-MRSA isolates from the United States, France, Switzerland, Australia, New Zealand, and Western Samoa indicated distinct genetic backgrounds associated with each geographic origin, although predominantly restricted to the agr3 background.
Abstract: Infections caused by community-acquired (CA)-methicillin-resistant Staphylococcus aureus (MRSA) have been reported worldwide. We assessed whether any common genetic markers existed among 117 CA-MRSA isolates from the United States, France, Switzerland, Australia, New Zealand, and Western Samoa by performing polymerase chain reaction for 24 virulence factors and the methicillinresistance determinant. The genetic background of the strain was analyzed by pulsed-field gel electrophoresis (PFGE) and multi-locus sequence typing (MLST). The CAMRSA strains shared a type IV SCCmec cassette and the Panton-Valentine leukocidin locus, whereas the distribution of the other toxin genes was quite specific to the strains from each continent. PFGE and MLST analysis indicated distinct genetic backgrounds associated with each geographic origin, although predominantly restricted to the agr3 background. Within each continent, the genetic background of CA-MRSA strains did not correspond to that of the hospital-acquired MRSA.
1,790 citations