Molecular epidemiology of Staphylococcus aureus colonization in 2 long-term care facilities.

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).     

Methicillin-resistant Staphylococcus aureus: a questionnaire survey of 75 long-term care facilities in western New York.

OBJECTIVES: To determine the frequency of recognition of methicillin-resistant Staphylococcus aureus (MRSA) as an infection control problem and its prevalence among long-term care facilities, and to evaluate whether certain long-term care facility characteristics such as bed size, ownership, level of infection control activity, and frequency of resident transfers to acute care hospitals are related to the recognition or prevalence of MRSA in this setting. DESIGN: Questionnaire survey. SETTING: Seventy-five long-term care facilities in the 8 counties of western New York. RESULTS: Seventy-five of 81 (92.6%) long-term care facilities returned a completed questionnaire. Seventy-nine percent were considered to have a "limited" level of infection control activity (part-time infection control practitioner who spent less than 10 hours a week on infection control activities). The larger the long-term care facility, the more time was spent on infection control activities (p = .01). Seventy-two percent of the long-term care facilities screened new admissions for MRSA by reviewing culture reports; 69% of the long-term care facilities had a specific infection control policy for MRSA. Sixteen of the 75 (21%) facilities felt they had an infection control problem with MRSA. By univariate analysis, the only characteristic significantly associated with this recognition was use of nurse practitioners or physician assistants by a facility (p < .05). Eighty-one percent of the 75 long-term care facilities had identified one or more patients with MRSA in the year prior to the survey. By univariate analysis, the only characteristics that were significantly associated with the number of residents with MRSA were the monthly average number of residents transferred to acute care facilities (p = .034) and facility bed size (p = .022); there was also a trend toward increasing intensity of infection control activities (p = .085). However, facility bed size and the average number of resident transfers per month to acute care facilities were strongly associated (p = .0002). By stepwise logistic regression analysis, only bed size was an independent predictor of the number of residents with MRSA. Many long-term care facilities had tried to eradicate MRSA; ciprofloxacin was most commonly used to eradicate MRSA. CONCLUSIONS: The vast majority of the 75 long-term care facilities in the 8 counties of western New York have identified patients with MRSA, although only a minority (21%) of them actually believed that an infection control problem existed. Facility size (a surrogate for the monthly average number of resident transfers to acute care facilities) seems to be an important factor in determining the number of residents with MRSA in long-term care facilities in our geographic region. The major longitudinal studies of MRSA in such facilities have so far been done only in Veterans Affairs facilities. Further studies are needed in freestanding long-term care facilities, the largest group of long-term care facilities in the United States, to determine the epidemiology of MRSA in this setting and to develop practical and valid infection control methods for residents with MRSA.     

Methicillin-resistant Staphylococcus aureus in U.S. hospitals, 1975-1991.

OBJECTIVES: Analyze changes that have occurred among U.S. hospitals over a 17-year period, 1975 through 1991, in the percentage of Staphylococcus aureus resistant to beta-lactam antibiotics and associated with nosocomial infections. DESIGN: Retrospective review. The percentage of methicillin-resistant S aureus (MRSA) was defined as the number of S aureus isolates resistant to either methicillin, oxacillin, or nafcillin divided by the total number of S aureus isolates for which methicillin, oxacillin, or nafcillin susceptibility test results were reported to the National Nosocomial Infections Surveillance (NNIS) System. SETTING: NNIS System hospitals. RESULTS: Of the 66,132 S aureus isolates that were tested for susceptibility to methicillin, oxacillin, or nafcillin during 1975 through 1991, 6,986 (11%) were resistant to methicillin, oxacillin, or nafcillin. The percentage MRSA among all hospitals rose from 2.4% in 1975 to 29% in 1991, but the rate of increase differed significantly among 3 bed-size categories: < 200 beds, 200 to 499 beds, and > or = 500 beds. In 1991, for hospitals with < 200 beds, 14.9% of S aureus isolates were MRSA; for hospitals with 200 to 499 beds, 20.3% were MRSA; and for hospitals with > or = 500 beds, 38.3% were MRSA. The percentage MRSA in each of the bed-size categories rose above 5% at different times: in 1983, for hospitals with > or = 500 beds; in 1985, for hospitals with 200 to 499 beds; and in 1987, for hospitals with < 200 beds. CONCLUSIONS: This study suggests that hospitals of all sizes are facing the problem of MRSA, the problem appears to be increasing regardless of hospital size, and control measures advocated for MRSA appear to require re-evaluation. Further study of MRSA in hospitals would benefit our understanding of this costly pathogen.     

Methicillin-resistant Staphylococcus aureus in neonatal intensive care unit

A neonatal intensive care unit outbreak was caused by a strain of methicillin-resistant Staphylococcus aureus previously found in the community (ST45-MRSA-IV). Fifteen infected neonates were identified, 2 of whom died. This outbreak illustrates how a rare community pathogen can rapidly spread through nosocomial transmission.     

Methicillin-resistant Staphylococcus aureus: associated morbidity and effectiveness of control measures

The strain of methicillin-resistant Staphylococcus aureus (MRSA) prevalent in south-east England produced in one acute hospital in a year 40 infections (bacteraemia, pneumonia and surgical wound, skin and urinary tract infections) with three attributable deaths. Rigorous measures succeeded in controlling the outbreak despite its extent, but our results suggest that less stringent measures could fail to control outbreaks of this scale. Several subsequent localized outbreaks within the hospital, probably caused by separate re-introductions of MRSA from other hospitals, were controlled by re-instigation of control measures on individual wards. The overall success of the intervention was shown by the decline in the incidence of MRSA infections from 27 in the 6 months beforehand to 2 in the most recent 6 months, and by the decline in the prevalence of colonization among patients 10 or more days in hospital from 52% immediately before the intervention to 3% 7 months after it. The incidence of attributable morbidity and death without control measures warrants a concerted effort to tackle the epidemic in all affected hospitals in Britain.     

Methicillin-resistant Staphylococcus aureus in a general intensive care unit

Methicillin-resistant Staphylococcus aureus (MRSA) has presented special problems in intensive care units (ICUs) because of the difficulties in implementing infection control measures. The prevalence and rate of acquisition of MRSA were studied over thirty months in a nine-bed ICU. Nasal and groin swabs were taken on admission and then weekly, and other cultures as clinically indicated. Of 1361 admissions 119 were MRSA-positive on arrival. 21 cases had been identified before admission and the remainder were detected by screening; in 57 the positive result was known only after discharge. Of the 1242 admissions initially negative 68 acquired MRSA while in the ICU. The ICU had no known MRSA-positive patients on 185 (20.3%) of 914 days, the longest sequence being 17 days. Positive patients occupied 1387 (16.9%) of the 8226 available bed days. Length of stay predicted the risk of acquiring MRSA. Estimated from patients who completed each weekly screening cycle, the risk was 7.5% per week in the first week and 20.3% per week thereafter. The risk was not influenced by initial APACHE II score, the use of haemofiltration, or the number of MRSA-positive patients in the unit. The data suggest that a further 38 of those discharged between weekly screenings acquired MRSA, giving an incidence of 8.5%. MRSA was grown from blood in 17 patients, and from sputum in 53 (ICU-acquired in 18% and 47%). This study suggests that nearly 10% of admissions to a general ICU will be MRSA-positive, of whom only half will be identified before discharge. With standard prevention the risk of previously negative patients acquiring MRSA approximates to 1% per day in the first week and 3% per day thereafter, with nearly one-fifth progressing to bacteraemia; one-half will have MRSA in sputum. Patients with longer stays constitute a high-risk minority for whom additional measures such as decontamination with oropharyngeal and enteral vancomycin should be considered.     

Methicillin-resistant Staphylococcus aureus, Western Australia

Methicillin-resistant Staphylococcus aureus (MRSA) continues to be a notable cause of hospital-acquired infections. A statewide screening and control policy was implemented in Western Australia (WA) after an outbreak of epidemic MRSA in a Perth hospital in 1982. We report on statutory notifications from 1998 to 2002 and review the 20-year period from 1983 to 2002. The rate of reporting of community-associated Western Australia MRSA (WAMRSA) escalated from 1998 to 2002 but may have peaked in 2001. Several outbreaks were halted, but they resulted in an increase in reports as a result of screening. A notable increase in ciprofloxacin resistance during the study period was observed as a result of more United Kingdom epidemic MRSA (EMRSA) -15 and -16. WA has seen a persistently low incidence of multidrug-resistant MRSA because of the screening and decolonization program. Non-multidrug-resistant, community-associated WAMRSA strains have not established in WA hospitals.     

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.     

Methicillin-resistant Staphylococcus aureus in Taiwan

We found a virulent closely related clone (Panton-Valentine leukocidin-positive, SCCmec V:ST59) of methicillin-resistant Staphylococcus aureus in inpatients and outpatients in Taiwan. The isolates were found mostly in wounds but were also detected in blood, ear, respiratory, and other specimens; all were susceptible to ciprofloxacin, gentamicin, and trimethoprim-sulfamethoxazole.     

Methicillin-resistant Staphylococcus aureus: awareness and perceptions

The purpose of this study was to investigate levels of awareness and the perceived risk of contracting methicillin-resistant Staphylococcus aureus (MRSA) amongst patients/visitors and employees of the UK National Health Service (NHS). Differences between the two cohorts were also investigated, particularly sources of information about MRSA. In March 2005, a piloted questionnaire was circulated to 50 patients/visitors and 100 NHS employees (25 doctors, 25 nurses, 25 domestics and 25 porters). No information was returned from porters, but the overall response rate was 67%. There was a high level of awareness of MRSA among both patients/visitors (94%) and NHS employees (100%). General media was the most common source of information for patients/visitors (68%) compared with 24% of NHS employees (P < 0.01). Perceived risk of contracting MRSA was very similar among patients/visitors and NHS employees (34% vs 35%, P > 0.10). Fifty-two percent of doctors felt that they were at risk compared with 13% of domestic employees. In conclusion, this study showed a high level of awareness among the general public and healthcare workers alike.     

Methicillin-resistant Staphylococcus aureus in Canadian aboriginal people.

We describe 279 hospitalized Canadian aboriginals in whom methicillin-resistant Staphylococcus aureus (MRSA) was detected. They were identified in 38 Canadian hospitals from 1995 through 2002. Compared with nonaboriginals, aboriginals were more likely to be younger than 18 years of age (OR, 1.8; P<.0001), to have had an MRSA infection (OR, 3.8; P<.0001), and to have had MRSA isolated from specimens of skin or soft tissue (OR, 4.1; P=.016). The clinical features of MRSA infection in aboriginals are distinct from those in the general patient population with MRSA infection in Canadian hospitals, and the genetic background of MRSA isolates from aboriginals also varies from that of strains from the non-aboriginal population.