Epidemiology of methicillin-resistant Staphylococcus aureus at a children's hospital.

OBJECTIVE: To describe the relative contribution of and risk factors for both community-acquired and nosocomial methicillin-resistant Staphylococcus aureus (MRSA) infections. DESIGN: Retrospective cohort study. SETTING: 270-bed, tertiary-care children's hospital. PARTICIPANTS: All MRSA-infected children from whom MRSA was recovered between October 1, 1999, and September 30, 2001. METHODS: Demographic, clinical, and risk factor data were abstracted from medical records. Categorical variables were analyzed using the chi-square or Fisher's exact test and continuous variables were analyzed using the Mann-Whitney test. RESULTS: Of the 62 patients with new MRSA infection, 37 had community-acquired MRSA and 25 had nosocomial MRSA. Most community-acquired MRSA infections were of the skin and soft tissue, the middle ear, and the lower respiratory tract. Nosocomial MRSA infections occurred in the lower respiratory tract, the skin and soft tissue, and the blood. Risk factors for infection, including underlying medical illness, prior hospitalization, and prior surgery, were similar for patients with community-acquired MRSA and nosocomial MRSA. History of central venous catheterization and previous endotracheal intubation was more common in patients with nosocomial MRSA. Only 3 patients with community-acquired MRSA had no identifiable risk factor other than recent antibiotic use. Resistance for clindamycin, erythromycin, and levofloxacin was similar between strains of community-acquired MRSA and nosocomial MRSA. CONCLUSIONS: Similarities in patient risk factors and resistance patterns of isolates of both community-acquired and nosocomial MRSA suggest healthcare acquisition of most MRSA. Thus, classifying MRSA as either community acquired or nosocomial underestimates the amount of healthcare-associated MRSA.     

Four pediatric deaths from community-acquired methicillin-resistant Staphylococcus aureus — Minnesota and North Dakota, 1997-1999

Methicillin-resistant Staphylococcus aureus (MRSA) is an emerging community-acquired pathogen among patients without established risk factors for MRSA infection (e.g., recent hospitalization, recent surgery, residence in a long-term-care facility [LTCF], or injecting-drug use [IDU]) (1). Since 1996, the Minnesota Department of Health (MDH) and the Indian Health Service (IHS) have investigated cases of community-acquired MRSA infection in patients without established risk factors. This report describes four fatal cases among children with community-acquired MRSA; the MRSA strains isolated from these patients appear to be different from typical nosocomial MRSA strains in antimicrobial susceptibility patterns and pulsed-field gel electrophoresis (PFGE) characteristics.     

Father-to-infant transmission of community-acquired methicillin-resistant Staphylococcus aureus in a neonatal intensive care unit.

Methicillin-resistant Staphylococcus aureus (MRSA) is increasingly being recognized as a cause of community-acquired infection. Its transmission in neonatal intensive care units (NICUs) has reportedly been linked to a few cases of community-acquired MRSA (CA-MRSA) infection. Here, I describe a case of CA-MRSA transmission from a father to his child in a NICU. Recognition that CA-MRSA may be transmitted in a hospital setting raises important issues for MRSA infection control and treatment options.     

Community-acquired methicillin-resistant Staphylococcus aureus infection in Singapore is usually "healthcare associated".

OBJECTIVE: To assess the frequency of community-acquired methicillin-resistant Staphylococcus aureus (MRSA) infections. SETTING: A teaching hospital in Singapore. METHODS: Prospectively collected surveillance data were reviewed during a 1-year period to determine the extent and origin of community-acquired MRSA infections. RESULTS: Whereas 32% of 383 MRSA infections were detected less than 48 hours after hospital admission and would, by convention, be classified as "community acquired," all but one of these were among patients who had been exposed to outpatient centers including dialysis or chemotherapy clinics, visiting nurses, community hospitals, or all three. CONCLUSIONS: With health care increasingly being delivered in an outpatient setting, community-acquired MRSA infections are often acquired in hospital-related sites and most may be more accurately described as "healthcare acquired." Infection control measures need to move beyond the traditional paradigm of acute care hospitals to effectively control the spread of resistant pathogens.     

Healthcare-associated Staphylococcus aureus bacteremia and the risk for methicillin resistance: is the Centers for Disease Control and Prevention definition for community-acquired bacteremia still appropriate?

OBJECTIVE: To evaluate a new classification for bloodstream infections that differentiates hospital acquired, healthcare associated, and community acquired in patients with blood cultures positive for Staphylococcus aureus. DESIGN: Prospective, observational study. SETTING: Three tertiary-care, university-affiliated hospitals in Dublin, Ireland, and Strasbourg, France. PATIENTS: Two hundred thirty consecutive patients older than 18 years with blood cultures positive for S. aureus. METHODS: S. aureus bacteremia (SAB) was defined as hospital acquired if the first positive blood culture was performed more than 48 hours after admission. Other SABs were classified as healthcare associated or community acquired according to the definition proposed by Friedman et al. When available, strains of methicillin-resistant Staphylococcus aureus (MRSA) were analyzed by pulsed-field gel electrophoresis (PFGE). RESULTS: Eighty-two patients were considered as having community-acquired bacteremia according to the Centers for Disease Control and Prevention (CDC) classification. Of these 82 patients, 56% (46) had healthcare-associated SAB. MRSA prevalence was similar in patients with hospital-acquired and healthcare-associated SAB (41% vs 33%; P > .05), but significantly lower in the group with community-acquired SAB (11%; P < .03). PFGE of MRSA strains showed that most community-acquired and healthcare-associated MRSA strains were similar to hospital-acquired MRSA strains. On multivariate analysis, Friedman's classification was more effective than the CDC classification for predicting MRSA. CONCLUSION: These results support the call for a new classification for community-acquired bacteremia that would account for healthcare received outside the hospital by patients with SAB.     

Community-acquired methicillin-resistant Staphylococcus aureus,Finland

Methicillin-resistant Staphylococcus aureus (MRSA) is no longer only hospital acquired. MRSA is defined as community acquired if the MRSA-positive specimen was obtained outside hospital settings or within 2 days of hospital admission, and if it was from a person who had not been hospitalized within 2 years before the date of MRSA isolation. To estimate the proportion of community-acquired MRSA, we analyzed previous hospitalizations for all MRSA-positive persons in Finland from 1997 to 1999 by using data from the National Hospital Discharge Register. Of 526 MRSA-positive persons, 21% had community-acquired MRSA. Three MRSA strains identified by phage typing, pulsed-field gel electrophoresis, and ribotyping were associated with community acquisition. None of the strains were multiresistant, and all showed an mec hypervariable region hybridization pattern A (HVR type A). None of the epidemic multiresistant hospital strains were prevalent in nonhospitalized persons. Our population-based data suggest that community-acquired MRSA may also arise de novo, through horizontal acquisition of the mecA gene.     

An outbreak of community-acquired foodborne illness caused by methicillin-resistant Staphylococcus aureus.

Infections with methicillin-resistant Staphylococcus aureus (MRSA) are increasingly community acquired. We investigated an outbreak in which a food handler, food specimen, and three ill patrons were culture positive for the same toxin-producing strain of MRSA. This is the first report of an outbreak of gastrointestinal illness caused by community-acquired MRSA.     

Epidemiology, control and treatments of antimicrobial resistances: highlights of the 45th ICAAC, Washington, 2005

For more than 20 years, hospital and community-acquired antimicrobial resistances regularly increase. In France, methicilline-resistant Staphylococcus aureus (MRSA) and extended-spectrum beta-lactamase-producing Enterobacteriaceae are the most common resistant pathogens. Previous hospitalisation, surgery, long length of stay, enteral feeding and antibiotic exposure are the main risk factors associated with nosocomial MRSA infections. To limit the emergence of resistances, control strategies have been implemented, based on isolation practices, healthcare workers education, strict hand hygiene and a controlled use of antibiotics. However, new antimicrobials acting by a novel mechanism of action are necessary in fighting the most resistant organisms. Therefore, the launch on the American market in June 2005 of tigecycline, a first-in-class glycylcycline indicated in the treatment of complicated skin and skin structure infections and complicated intra-abdominal infections, will provide to physicians a new therapeutic option against hospital or community-acquired resistant pathogens. The data presented to ICAAC indicate its expended broad spectrum of in vitro activity against Gram positives, Gram negatives, anaerobes and against number of difficult-to-treat resistant isolates, such as hospital or community-acquired MRSA, vancomycine resistant Enterococcus but also ESBL-producing organisms.     

Clinical experience and outcomes of community-acquired and nosocomial methicillin-resistant Staphylococcus aureus in a northern Australian hospital

Methicillin-resistant Staphylococcus aureus (MRSA) is a well-recognized cause of hospital-acquired sepsis. We reviewed the clinical features of a new variant of community-acquired MRSA originally described from the Kimberley region of northern Western Australia (WA MRSA). This strain has become an increasing cause of community- and hospital-acquired sepsis at Royal Darwin Hospital (RDH) in the Northern Territory, especially in Aboriginal Australians from remote communities. Fifty percent of WA MRSA was community-acquired, with 76% in Aboriginals. Like the MRSA from eastern Australia (EA MRSA), WA MRSA commonly caused skin sepsis but was less likely to cause respiratory or urinary infections compared with EA MRSA. Twelve out of 125 (9·6%) WA MRSA and 7/93 (7·5%) EA MRSA infections were septicaemias. Septicaemia due to WA MRSA occurred in adult medical patients, especially those with temporary haemodialysis catheters, while EA MRSA septicaemia occurred throughout the hospital. Aboriginal people were more likely to develop both community- and hospital-acquired WA MRSA septicaemia [overall relative risk (RR) 12·3 (95% CI 3·7–40·7)]. Control of WA MRSA requires policies to reduce transmission in both hospitals and communities. Community-based control programmes need support for individual patient management, improved housing and hygiene, control of skin sepsis and appropriate use of antibiotics, especially in rural Aboriginal communities in northern Australia.     

Aktuelle Daten und Trends zu Methicillin-resistenten Staphylococcus aureus (MRSA)

Nosocomial infections caused by methicillin-resistant Staphylococcus aureus (MRSA) are a problem in hospital settings worldwide. The National Reference Centre for Staphylococci performs molecular typing on a representative sample set of MRSA isolates from German hospitals for assessing long-term trends thus following the dynamics of emergence and spread of MRSA clones. The article focuses on recent data concerning antibiotic resistance and epidemic MRSA in nosocomial settings and also reflects the impact of community-acquired MRSA and MRSA from zoonotic reservoirs. Identifying common and newly emerging clones is an on-going challenge in the changing epidemiology of MRSA and prevention of further spread needs molecular surveillance.     

Community-acquired methicillin-resistant Staphylococcus aureus among military recruits

We report an outbreak of 235 community-acquired methicillin-resistant Staphylococcus aureus (MRSA) infections among military recruits. In this unique environment, the close contact between recruits and the physical demands of training may have contributed to the spread of MRSA. Control measures included improved hygiene and aggressive clinical treatment.     

Methicillin-resistant Staphylococcus aureus in children, Taiwan

Highly virulent community-acquired methicillin-resistant Staphylococcus aureus (CA-MRSA) with Panton-Valentine leukocidin (PVL) is common worldwide. Using antimicrobial drug susceptibility testing, staphylococcal cassette chromosome mec typing, exotoxin profiling, and pulsed-field gel electrophoresis typing, we provide evidence that supports the relationship between nasal strains of PVL-positive MRSA and community-acquired disease.     

Staphylococcus aureus with reduced susceptibility to vancomycin--Illinois, 1999

Staphylococcus aureus is one of the most common causes of hospital- and community-acquired infections. Nosocomial methicillin-resistant S. aureus (MRSA) infections have become common, and cases of community-acquired MRSA infections also have occurred. Since 1996, vancomycin-intermediate S. aureus (VISA; vancomycin minimum inhibitory concentration [MIC = 8-16 microg/mL) has been identified in Europe, Asia, and the United States. The emergence of reduced vancomycin susceptibility in S. aureus increases the possibility that some strains will become fully resistant and that available antimicrobial agents will become ineffective for treating infections caused by such strains. This report describes the fourth case of confirmed VISA from a patient in the United States.     

Staphylococcus aureus,a successful pathogen

Staphylococcus aureus is a dreadful pathogen for mankind, causing boils, abscesses, wound infections, osteomyelitis, septicaemia, endocarditis, pneumonia, toxic shock syndrome, scalded skin syndrome, and food poisoning. The development of penicillin-, methicillin-, and vancomycin-resistant strains shows that S. aureus has an enormous adaptive power. Most methicillin-resistant strains of S. aureus (MRSA) are hospital-acquired, although an increasing number are reported to be community-acquired. A limited number of clones of MRSA have spread all over the world. Since most community-acquired MRSA can be traced back to some contact with health care, MRSA can still best be combatted by control measures in health care institutions. In this respect, the Netherlands and Scandinavian countries have been very successful so far. S. aureus has many virulence factors at its disposal: structural components, enzymes and three types of toxins. Panton-Valentine leukocidin (PVL) has received attention as a factor causing severe pneumonia with high mortality. A strain combining methicillin resistance and PVL has spread through France. Recently, the genome of an MRSA strain has been unravelled. Its structure illustrates how well S. aureus can adapt itself and acquire properties of other microorganisms. This genetic knowledge may lead to new strategies to combat S. aureus.     

耐甲氧西林金黄色葡萄球菌医院感染及社区感染的流行特点

目的了解住院患者中耐甲氧西林金黄色葡萄球菌(MRSA)医院感染及社区感染的流行特点,为积极预防和控制MRSA的感染与传播提供科学依据。方法 2008年7月1日-2010年12月31日,由专职人员每天根据细菌培养结果按照统一的方法到病房对患者进行前瞻性调查,2005年1月1日-2008年6月30日对金黄色葡萄球菌培养阳性住院患者进行回顾性调查。结果 MRSA医院感染率为0.10‰,入院患者中MRSA社区发病的感染率为1.40‰;医院感染中MRSA感染率为70.40%,显著高于社区感染感染率为46.04%(P<0.001);MRSA感染主要发生在重症监护病房(ICU)、内科及干部病房,呼吸系统的感染;MRSA感染率最高的是ICU和干部病房,>80.0%,呼吸系统和泌尿系统的感染。结论金黄色葡萄球菌耐药状况在医院内形势依然严峻,预防与控制MRSA感染重点在ICU、内科及干部病房,主要发生在呼吸系统的感染。     

Methicillin-resistant Staphylococcus aureus (MRSA) in the community

Methicillin-resistant Staphylococcus aureus (MRSA) infections have been confined to healthcare centres for decades. However, MRSA infections are increasingly seen in young healthy individuals with no exposure to healthcare centres. These community-acquired MRSA (CA-MRSA) strains differ from healthcare-associated MRSA (HA-MRSA) strains in various ways. For example, CA-MRSA is strongly associated with the staphylococcal cassette chromosome mec (SCCmec) type IV and the toxin Panton-Valentine leukocidin. CA-MRSA spreads relatively easily but often remains susceptible to non-3-lactam antibiotics. Given the epidemic potential of CA-MRSA strains, there is a high probability that the number of CA-MRSA infections will increase in The Netherlands. In order to prevent and control CA-MRSA outbreaks in the community successfully, the restrictive Dutch antibiotic policy must be followed with strict infection prevention measures.     

Severe community-acquired pneumonia due to Staphylococcus aureus, 2003-04 influenza season

During the 2003-04 influenza season, 17 cases of Staphylococcus aureus community-acquired pneumonia (CAP) were reported from 9 states; 15 (88%) were associated with methicillin-resistant S. aureus (MRSA). The median age of patients was 21 years; 5 (29%) had underlying diseases, and 4 (24%) had risk factors for MRSA. Twelve (71%) had laboratory evidence of influenza virus infection. All but 1 patient, who died on arrival, were hospitalized. Death occurred in 5 (4 with MRSA). S. aureus isolates were available from 13 (76%) patients (11 MRSA). Toxin genes were detected in all isolates; 11 (85%) had only genes for Panton-Valentine leukocidin. All isolates had community-associated pulsed-field gel electrophoresis patterns; all MRSA isolates had the staphylococcal cassette chromosome mec type IVa. In communities with a high prevalence of MRSA, empiric therapy of severe CAP during periods of high influenza activity should include consideration for MRSA.     

Community-acquired methicillin-resistant Staphylococcus aureus in institutionalized adults with developmental disabilities

Methicillin-resistant Staphylococcus aureus (MRSA) has recently been reported to emerge in the community setting. We describe the investigation and control of a community-acquired outbreak of MRSA skin infections in a closed community of institutionalized adults with developmental disabilities. In a 9-month period in 1997, 20 (71%) of 28 residents had 73 infectious episodes. Of the cultures, 60% and 32% obtained from residents and personnel, respectively, grew S. aureus; 96% and 27% were MRSA. All isolates were genetically related by pulsed-field gel electrophoresis and belonged to a phage type not previously described in the region. No known risk factors for MRSA acquisition were found. However, 58 antibiotic courses had been administered to 16 residents during the preceding 9 months. Infection control measures, antibiotic restriction, and appropriate therapy resulted in successful termination of this outbreak. Selective antibiotic pressure may result in the emergence, persistence, and dissemination of MRSA strains, causing prolonged disease.