Impact of screening for MRSA carriers at hospital admission on risk-adjusted indicators according to the imported MRSA colonization pressure

We evaluated the impact of the different components of a screening programme of methicillin-resistant Staphylococcus aureus (MRSA) carriers at hospital admission on the value of two risk-adjusted rates: the proportion of imported MRSA and an indicator of the MRSA colonization pressure (ICP), and the incidence of MRSA acquired and detected in our hospital. Indicators were calculated: (1) with no screening programme; (2) with a programme limited to the intensive care unit (ICU); (3) with a programme extended to patients with risk factors for MRSA carriage hospitalized in non-ICU wards. The programme included an automatic alert. Systematic sampling of patients with risk factors hospitalized in non-ICU settings detected nearly 50% of carriers at admission. The proportion of MRSA imported into our hospital varied from 35.4% without any screening programme to 71.8% when all components of our screening programme were considered (P<10(-4)). The ICP varied from 3.1% (31/985) with the complete programme to 10.4% (31/297) without any screening programme (P<10(-6)). Screening patients with risk factors for MRSA carriage hospitalized in non-ICU wards resulted in a 51% increase of the calculated proportion of imported strains and a 58% decrease of the ICP. The two studied indicators were strongly dependent on the screening strategy for MRSA carriers implemented at admission. The screening strategy for patients admitted to non-ICU wards who have risk factors for MRSA carriage seems to be the determinant for the interpretation of certain risk-adjusted indicators of MRSA cross-transmission. Comparisons of these indicators must consider the setting in which the screening programmes are implemented.     

Comparison of systematic versus selective screening for methicillin-resistant Staphylococcus aureus carriage in a high-risk dermatology ward.

OBJECTIVE: To compare two strategies for screening methicillin-resistant Staphylococcus aureus (MRSA) carriers in a high-risk dermatology ward: systematic screening of all admitted patients versus selective screening of patients at risk. DESIGN: The two strategies were applied prospectively during two consecutive periods. In period A (8.5 months), only patients transferred from other wards, or with a history of prior hospitalization, or presenting chronic wounds or disease with denuded skin were considered at high risk of MRSA carriage and sampled. In period B (7.5 months), all admitted patients were systematically screened. End-points were the number of patients having a MRSA-positive screening sample on admission during period B and having none of the risk factors used in period A, the rate of imported MRSA cases, and the rate of acquired cases. SETTING: A 1,032-bed university hospital with a 19-bed inpatient dermatology ward, a referral center for toxic epidermal necrolysis and severe extensive dermatoses. PATIENTS: The study included 729 dermatology inpatients (370 in period A and 359 in period B). RESULTS: During period A, screening samples were obtained on admission for 30% of patients (77% of the patients at risk) and identified 25 MRSA carriers. During period B, 90.5% of admitted patients were screened, and 26 MRSA carriers were detected on admission; all of these patients belonged to at least one predefined category at risk for carriage. Overall rates of imported and acquired cases were similar between the two periods (6.8% vs 7.5%, and 2.9% vs 2.4%, respectively). CONCLUSIONS: A screening strategy targeted to patients at risk of harboring MRSA has similar sensitivity and is more cost-effective than a strategy of systematic screening to identify MRSA carriers on admission.     

Carriage of methicillin-resistant Staphylococcus aureus among hospital employees: prevalence, duration, and transmission to households.

OBJECTIVE: To assess the prevalence and duration of methicillin-resistant Staphylococcus aureus (MRSA) carriage among hospital employees and transmission to their households. DESIGN: A point-prevalence survey of MRSA carriage (nasal swabbing) of staff and patients throughout the hospital; a prevalence survey of MRSA carriage in 2 medical wards, with carriers observed to estimate carriage duration; and evaluation of transmission to MRSA-positive workers' families. All MRSA isolates were analyzed by pulsed-field gel electrophoresis. During the study, no MRSA outbreak was detected among hospitalized patients. SETTING: A 600-bed, public tertiary-care teaching hospital near Paris. RESULTS: Sixty MRSA carriers were identified among 965 healthcare providers (prevalence, 6.2%; CI95, 4.7%-7.7%). Prevalence was higher in staff from clinical wards than from elsewhere (9.0% vs 2.1%; P < .0001). Identity of isolates from employees and patients varied from 25% in medical wards to 100% in the long-term-care facility. MRSA carriage was identified in 14 employees from 2 medical wards (prevalence, 19.4%; CI95, 10.3%-28.5%). Prevalence depended on the length of service in these wards. Transmission to households was investigated in 10 MRSA-positive workers' families and was found in 4. All isolates from each family were identical. CONCLUSIONS: Few data are available concerning the prevalence of MRSA carriers among hospital employees in the absence of an outbreak among patients. MRSA transmission between patients and employees likely depends on the frequency and duration of exposure to MRSA-positive patients and infection control measures employed. Frequent transmission of MRSA from colonized healthcare workers to their households was documented.     

High prevalence of carriage of methicillin-resistant Staphylococcus aureus at hospital admission in elderly patients: implications for infection control strategies.

BACKGROUND: Despite contact isolation precautions for patients with methicillin-resistant Staphylococcus aureus (MRSA), MRSA infections are increasing in many countries. OBJECTIVE: To evaluate the role of a potential unrecognized reservoir of MRSA carried by patients in acute care wards, we determined the prevalence of MRSA at hospital admission, with special emphasis on screening-specimen yields. SETTING: A 1100-bed teaching hospital in Paris, France. METHODS: Nasal screening cultures were performed at admission to a tertiary-care teaching hospital for patients older than 75 years. RESULTS: MRSA was isolated from 63 (7.9%) of 797 patients. On the multivariate analysis, variables significantly associated with MRSA carriage were presence of chronic skin lesions (adjusted odds ratio [AOR], 5.10; 95% confidence interval [CI95], 2.52-10.33); transfer from a nursing home, rehabilitation unit, or long-term-care unit (AOR, 4.52; CI95, 2.23-9.18); and poor chronic health status (AOR, 1.80; CI95, 1.02-3.18). Without admission screening, 84.1% of MRSA carriers would have been missed at hospital admission and 76.2% during their hospital stay. Furthermore, 81.1% of days at risk for MRSA dissemination would have been spent without contact isolation precautions had admission screening not been performed. CONCLUSIONS: MRSA carriage at hospital admission is far more prevalent than MRSA-positive clinical specimens. This may contribute to failure of contact isolation programs. Screening cultures at admission help to identify the reservoir of unknown MRSA patients.     

The Nottingham Staphylococcus aureus population study: prevalence of MRSA among the elderly in a university hospital

A prevalence survey of methicillin-resistant Staphylococcus aureus (MRSA) in elderly patients (65 years and older) three weeks after admission to a university hospital was performed. Risk factors associated with hospital MRSA carriage were determined. The design was a cross-sectional patient-based study and all adult wards at the University Hospital Nottingham (1600 beds) were included. Three hundred and forty-two elderly individuals (65 years and older) were enrolled into the study on day 21 after admission. One hundred and twenty patients [35.08% (95% confidence intervals 29.93-40.25%)] carried S. aureus. MRSA was isolated from 54 patients. The MRSA prevalence was 158/1000 (95% CI 119-197/1000 patients). Independent risk factors for MRSA carriage in the hospital were exposure to ampicillin [adjusted odds ratio 4.1 (95% CI 1.28-13.14)] and ciprofloxacin [17.1 (95% CI 2.91-99.90)]. Forty-one MRSA isolates (75.9%) belonged to the epidemic type EMRSA 15, seven isolates to EMRSA 16 (12.9%) and six isolates were sporadic strains as determined by genetic typing. It can be expected that among this defined risk group, between 187 and 331 patients carried MRSA on discharge in the year 2000. MRSA carriage is frequent and detected in only 15% of actual carriers amongst elderly patients by routine clinical investigations three weeks after admission. The only significant risk factor identified by multivariate logistic regression was antibiotic chemotherapy. The repeated finding of a strong association between MRSA colonization and previous ciprofloxacin exposure demands attention and indicates that fluoroquinolones should be used prudently in institutions where MRSA is endemic.     

Low prevalence of methicillin-resistant Staphylococcus aureus (MRSA) at hospital admission in the Netherlands: the value of search and destroy and restrictive antibiotic use

In the Netherlands, less than 1% of clinical isolates of Staphylococcus aureus are methicillin-resistant (MRSA). A national search and destroy policy prevents MRSA from becoming endemic. Some MRSA outbreaks cannot be related to patients at risk for MRSA carriage. This study was designed to measure the prevalence of MRSA among patients without risk factors for MRSA carriage at the time of admission to the hospital. In four Dutch hospitals, patients admitted to non-surgical departments in the period 1999-2000 were screened for MRSA nasal carriage. Nasal swabs were streaked on 5% sheep blood agar (BA), submerged in a selective broth, and incubated for two to three days at 35 degrees C. Colonies suspected of being S. aureus were identified with an agglutination test. Susceptibility testing was performed by an automated system and additional oxacillin disk diffusion. Methicillin resistance was confirmed by a DNA hybridization test and mecA PCR. MRSA strains were genotyped by pulsed-field gel electrophoresis (PFGE). Twenty-four percent (2332/9859) of the patients were S. aureus nasal carriers. Only three (0.03%) patients were MRSA carriers. These patients were not repatriated, nor known to be MRSA carriers before screening. Genotyping revealed that the strains were not clonally related and were not related to MRSA outbreaks in the hospital where the patients were admitted. We conclude that at routine admission to a Dutch hospital (excluding high-risk foreign admissions) the MRSA prevalence is low (0.03%), due to the Dutch search and destroy policy and restrictive antibiotic prescribing.     

Comparison of routine prophylaxis with vancomycin or cefazolin for femoral neck fracture surgery: microbiological and clinical outcomes.

OBJECTIVE: To assess the impact of antibiotic prophylaxis on the emergence of vancomycin-resistant strains of Enterococcus faecium, Enterococcus faecalis, and Staphylococcus aureus and the incidence of surgical site infection (SSI) after vancomycin or cefazolin prophylaxis for femoral neck fracture surgery. DESIGN: Prospective cohort study. SETTING: A hospital with a high prevalence of methicillin-resistant S. aureus (MRSA) carriage. PATIENTS: All patients admitted with a femoral neck fracture from March 1, 2004 through February 28, 2005 were prospectively identified and screened for MRSA and vancomycin-resistant (VRE) carriage at admission and at day 7. Deep incisional and organ/space SSIs were also recorded. RESULTS: Of 263 patients included in the study, 152 (58%) received cefazolin and 106 (40%) received vancomycin. At admission, the prevalence of MRSA carriage was 6.8%; it was 12% among patients with risk factors and 2.2% among patients with no risk factors (P=.002). At day 7 after surgery, there were 6 patients (2%) who had hospital-acquired MRSA, corresponding to 0.7% in the cefazolin group and 5% in the vancomycin group (P=.04); none of the MRSA isolates were resistant to glycopeptides. The rate of VRE carriage at admission was 0.4%. Three patients (1%) had acquired carriage of VRE (1 had E. faecium and 2 had E. faecalis); all 3 were in the cefazolin group (2% of patients) and none in the vancomycin group (P=.27). Eight SSIs (3%) occurred, 4% in the cefazolin group and 2% in the vancomycin group (P=.47). CONCLUSIONS: This preliminary study demonstrates that cefazolin and vancomycin prophylaxis have similar impacts on the emergence of glycopeptide-resistant pathogens. Neither MRSA infection nor increased rates of SSI with other bacteria were observed in the vancomycin group, suggesting that a larger multicenter study should be initiated.     

Epidemiology of hospital-acquired infections in cirrhotic patients: effect of carriage of methicillin-resistant Staphylococcus aureus and influence of previous antibiotic therapy and norfloxacin prophylaxis.

We assessed the prevalence of carriage of methicillin-resistant Staphylococcus aureus (MRSA) in anterior nares and stools, and of third-generation cephalosporin resistant enterobacteriaceae and non-fermenting gram-negative bacilli (RE/RNF) in stools of 748 hospitalized long-stay cirrhotic patients. We also evaluated the consequences of carriage on the epidemiology of hospital-acquired spontaneous bacterial peritonitis, bacteraemia and urinary tract infection (UTI) in these patients. The prevalence of carriage of MRSA and RE/RNF was 16.7% and 14.7% respectively. Whereas RE/RNF carriage did not lead to an increased risk of infection due to RE/RNF, the overall risk of infections caused by MRSA was more than tenfold higher in MRSA carriers. MRSA and RE/RNF carriers had received prior antibiotic therapy to a greater extent than non-carriers (P < 0.001) and MRSA carriers had received prior norfloxacin prophylaxis to a greater extent than the two other groups (P < 0.02). The mortality rate during hospital stay was higher in MRSA and RE/RNF carriers than in non-carriers (P < 0.001). Pugh score (P < 0.0001), age (P < 0.0001), MRSA carriage (P = 0.0018) and bacteraemia (P = 0.0017) were associated independently with mortality. MRSA carriage in hospitalized cirrhotic patients leads to the emergence of infections due to this strain, mainly SBP and bacteraemia. Prior antibiotic therapy and norfloxacin prophylaxis increase the risk of carriage of MRSA.     

Active screening in high-risk units is an effective and cost-avoidant method to reduce the rate of methicillin-resistant Staphylococcus aureus infection in the hospital.

OBJECTIVE: To evaluate the impact of active screening for methicillin-resistant Staphylococcus aureus (MRSA) on MRSA infection rates and cost avoidance in units where the risk of MRSA transmission is high. METHODS: During a 15-month period, all patients admitted to our adult medical and surgical intensive care units (ICUs) were screened for MRSA nasal carriage on admission and weekly thereafter. The overall rates of all MRSA infections and of nosocomial MRSA infection in the 2 adult ICUs and the general wards were compared with rates during the 15-month period prior to the start of routine screening. The percentage of patients colonized or infected with MRSA on admission and the cost avoidance of the surveillance program were also assessed. RESULTS: The overall rate of MRSA infections for all 3 areas combined decreased from 6.1 infections per 1,000 census-days in the preintervention period to 4.1 infections per 1,000 census-days in the postintervention period (P = .01). The decrease remained statistically significant when only nosocomial MRSA infections were examined (4.5 vs 2.8 infections per 1,000 census-days; P < .01), despite a corresponding increase during the postintervention period in the percentage of patients with onset of MRSA infection in the first 72 hours after admission to the general wards (46% to 81%; P < .005). A total of 3.7% of ICU patients were colonized or infected with MRSA on admission; MRSA would not have been detected in 91% of these patients if screening had not been performed. At a cost of Dollars 3,475/month for the program, we averted a mean of 2.5 MRSA infections/month for the ICUs combined, avoiding Dollars 19,714/month in excess cost in the ICUs. CONCLUSIONS: Even in a setting of increasing community-associated MRSA, active MRSA screening as part of a multi-factorial intervention targeted to high-risk units may be an effective and cost-avoidant strategy for achieving a sustained decrease of MRSA infections throughout the hospital.     

A clinical trial of mupirocin in the eradication of methicillin-resistant Staphylococcus aureus nasal carriage in a digestive disease unit

We assessed the incidence of nasal carriage of methicillin-resistant Staphylococcus aureus (MRSA) on admission, the rate of acquisition during the hospital stay and the relationship with subsequent infection in a digestive disease unit. The efficacy of a program of nasal carriage eradication with mupirocin was evaluated simultaneously. Over one year 484 patients were studied prospectively on admission for nasal and stool carriage of MRSA, then every week for nasal carriage. Nearly 70% (68.8%) of patients had chronic liver diseases. Nasal carriers were assigned to a five-day course of intranasal mupirocin ointment. One hundred and seventeen (24.2%) patients were MRSA positive, 57 (11.8%) of which were carriers on admission and 60 (12.4%) acquired carriage. Of these, 86 were treated with mupirocin with a success rate of 98.8% and 25.9% of them recolonized. Fourteen patients were retreated, to allow eradication in 71.4% of cases. Seventy percent of these became carriers again. One high-level mupirocin-resistant strain was isolated before treatment and seven during or after treatment. Hospital stay and stool carriage were independently associated with reacquisition (P=0.0105 and P=0.0462, respectively). Molecular analysis showed identity between the strains isolated from infection samples and from nasal swabs during the same week. For every patient who became recolonized, nasal strains isolated before and after eradication were the same in 70% of cases. Mortality during hospital stay was independently associated with age (P=0.0081), MRSA nasal carriage (P=0.02631), MRSA infection (P<0.0001) and liver disease (P=0.0017). This study did not show a change in the prevalence rate of infection in the unit during treatment with mupirocin. This treatment should only be attempted once due to the risk of emergence of high-level resistant strains.     

Sustained low prevalence of meticillin-resistant Staphylococcus aureus upon admission to hospital in The Netherlands

The prevalence of meticillin-resistant Staphylococcus aureus (MRSA) carriage at hospital admission in The Netherlands was 0.03% in 1999–2000. The aim of the present study was to assess whether the prevalence of MRSA carriage in The Netherlands has changed over the last few years. In five Dutch hospitals, 6496 unique patients were screened for nasal S. aureus carriage at hospital admission by microbiological culture between 1 October 2005 and 7 June 2007. In total, 2036 of 6496 (31.3%) patients carried S. aureus in their nose, and seven of 6496 (0.11%) patients were nasal carriers of MRSA. Compared with 1999–2000, the prevalence of MRSA carriage in the Dutch population at hospital admission has increased more than three fold; however, this increase was not significant (P = 0.06, Fisher’s exact test). This prevalence is still among the lowest in the world, probably as a result of the stringent Dutch infection control policy, and the restrictive use of antibiotics in The Netherlands.     

Prevalence of methicillin-resistant Staphylococcus aureus colonization in surgical patients,on admission to a Welsh hospital

Nosocomial infection with methicillin-resistant Staphylococcus aureus (MRSA) is on the increase and expensive to treat. Because surgical wound infection is one of the most frequent MRSA-induced infections with often disastrous consequences, it was decided to estimate the incidence and risk factors of MRSA colonization in surgical patients. All patients admitted to general surgical and orthopaedic wards were studied prospectively. At the time of admission, a detailed questionnaire was completed, nasal swabs and swabs of any pre-existing wound sites in each patient were sent for culture. Of 430 patients studied, 23 patients were positive for MRSA on admission. The prevalence of MRSA colonization in this study was 5.3% of whom 15 (65%) were nasal carriers and eight (35%) had MRSA colonization elsewhere. All nasal MRSA carriers had at least one documented hospital admission in the preceding year. Among the MRSA-positive patients, 10 (43%) either were admitted directly from, or had been previously admitted to, a nursing home. MRSA remains mainly a hospital-acquired infection although a significant proportion is acquired in the community. The risk factors identified were previous hospital admission, patients from nursing homes, male and aged over 70.     

Prevalence of and risk factors for methicillin-resistant Staphylococcus aureus carriage at hospital admission.

To determine the prevalence of and risk factors for methicillin-resistant Staphylococcus aureus (MRSA) carriage at the time of admission to our hospital, we screened the medical records of 1,128 patients for demographic and clinical data. The antimicrobial resistance pattern and genotype of MRSA isolates were studied. The prevalence of MRSA carriage at hospital admission was 1.4%. Older patients and patients previously admitted to healthcare centers were the most likely to have MRSA carriage at admission.     

Effect on MRSA transmission of rapid PCR testing of patients admitted to critical care

We report a significant reduction in the rate of meticillin-resistant Staphylococcus aureus (MRSA) transmission on a critical care unit when admission screening by culture was replaced with a same-day polymerase chain reaction (PCR) test. This was an observational cohort study, set in a 19-bed mixed medical and surgical adult critical care unit in southwest England. We studied 1305 patients admitted between April 2005 and February 2006. Standard MRSA culture methods were used to screen 612 patients between April 2005 and August 2005, and the IDI MRSA PCR test was used to screen 693 patients between September 2005 and February 2006. Standard infection control precautions were instituted when positive results were obtained by either method. Outcome measures included carriage rate, turnaround time for results and rate of subsequent MRSA transmission on the unit. The overall carriage rate on admission to the unit was 7.0%. Culture results were available in three working days, PCR results within one working day. The mean incidence of MRSA transmission was 13.89/1000 patient days during the culture phase and 4.9/1000 patient days during the PCR phase (relative risk reduction 0.65, 95% CI 0.28-1.07). PCR screening for MRSA on admission to critical care units is feasible in routine clinical practice, provides quicker results than culture-based screening and is associated with a significant reduction in subsequent MRSA transmission.     

A bundle of care to reduce colorectal surgical infections: an Australian experience

Staphylococcus aureus carriage increases the risk of infection. Demographic and microbiological data from adult patients with nasal S. aureus carriage were analysed in order to define effect modifiers of this association. Predictors for growth of S. aureus from clinical cultures were identified in a case-control study using bivariate and multi-variate logistic regression analysis. Between 1 January 2005 and 1 April 2009, 645 patients with nasal S. aureus colonization and documented follow-up of ≥90 days were identified; 159 (25%) patients were found to carry meticillin-resistant S.?aureus (MRSA). The median age of patients was 58 years, and 421 (65%) were male. During the subsequent 90 days, one or more clinical cultures were positive for S. aureus in 131 patients (20%). Multi-variate analysis identified a prior history of any S. aureus positive culture [adjusted odds ratio (aOR) 2.4, 95% confidence interval (CI) 1.5-3.8; P=0.0005) as an independent predictor of subsequent S. aureus infection. MRSA colonization was a predictor of infection in patients aged >40 years (aOR 2.5, 95% CI 1.4-4.1; P=0.0004), and even more so in patients aged ≤40 years (aOR 12.4, 95% CI 3.0-51; P=0.0005). Age >40 years was an additional independent risk?factor for meticillin-susceptible S. aureus carriers (aOR 3.0, 95% CI 1.2-7.8; P=0.02) but not for MRSA carriers. Preferential screening of patients at high risk for MRSA carriage and subsequent infection, as well as the absence of a universal policy for the use of decolonization regimens, may partly explain the relatively high risk of S. aureus infection in the patient population. MRSA carriers and older patients with recurrent S. aureus positive cultures may gain the greatest benefit from routine decolonization measures.     

Methicillin-resistant Staphylococcus aureus in people living and working in pig farms

We compared the prevalence of human and animal methicillin-resistant Staphylococcus aureus (MRSA) at pig farms in The Netherlands, and related this to individual and farm-level characteristics. More than half of the farms investigated (28/50) had MRSA in pigs or stable dust and about one third (15/50) of person(s) were identified as MRSA carriers. Human carriage was found only on farms with MRSA-positive pigs or dust. MRSA strains in human samples were the same spa-type as found in pigs and all were not typable by pulsed-field gel electrophoresis (NT-MRSA). Multivariate analyses showed that risk factors for human MRSA carriage were: working in pig stables (OR 40, 95% CI 8-209) and the presence of sows and finishing pigs (OR 9, 95% CI 3-30). Veterinary sample collectors sampling the pigs showed transient MRSA carriage only during the day of the farm visit. Working in pig stables with MRSA-positive pigs poses a high risk for acquiring MRSA, increasingly so when contact with live pigs is more intensive or long lasting.     

Meticillin-resistant Staphylococcus aureus carriage among district nurse patients and medical admissions in a UK district

We studied the prevalence of meticillin-resistant Staphylococcus aureus (MRSA) carriage in two defined community populations and assessed risk factors associated with MRSA colonization. The study was designed as a population prevalence survey and was carried out in the medical assessment unit (MAU) of the local hospital and the district nurse patient (DNP) population in Huntingdonshire. In all, 162 participants were recruited, 91 were from MAU and 71 from the DNP population. MRSA was found in 21.1% [confidence interval (CI): 11.6-30.4] of the DNP study population and 6.6% (CI 1.5-11.7) of the MAU study population. Factors found to be significantly associated with MRSA colonization were age (76.6 years, P=0.008), presence of wound/ulcer (P=0.012), hospital admission in the past year (P=0.017), past history of MRSA (P<0.001), and antibiotic use in the preceding six months (P=0.016). The only independent predictor for MRSA colonization was found to be past history of MRSA (adjusted odds ratio: 8.53; CI: 2.11-34.43; P=0.003). The DNP population are a significant reservoir for MRSA in the community and policies on screening high-risk patients need to reflect this.     

Long-term efficacy of mupirocin in the prevention of infections with meticillin-resistant Staphylococcus aureus in a gastroenterology unit

The long-term efficacy (55 months) of eradication of nasal carriage of meticillin-resistant Staphylococcus aureus (MRSA) by mupirocin was assessed for MRSA infections in a gastroenterology unit receiving patients for long hospital stays. In total, 2242 patients were included in the study; 92% had been hospitalized in another hospital before admission to the study department, 64% had chronic liver diseases (LD), 25% had miscellaneous medical conditions and 11% were admitted following gastroenterological surgery. Three consecutive periods were considered in the analysis. Nasal carriage at admission was similar in all three periods (10.9 vs 7.5 vs 8.6% in Periods 1, 2 and 3, respectively), while acquired nasal carriage decreased in the whole population (14.3 vs 16.2 vs 10.2% in Periods 1, 2 and 3, respectively, P=0.006) and in LD patients (15.8 vs 18.7 vs 11.9% in Periods 1, 2 and 3, respectively, P=0.018). The incidence of MRSA infections (N per total number of hospitalization-days) was 1.41 per 1000 in the year before initiation of eradication, 1.40 in Period 1, 0.74 in Period 2 and 0.59 in Period 3 (P=0.022). The incidence of MRSA infections among patients was 7.0% in Period 1, 3.7% in Period 2 and 3.1% in Period 3 in LD patients (P=0.0062). The corresponding figures were 5.5, 3.0 and 2.4% for the whole population (P=0.0024). The mortality caused by MRSA was 0.31, 0.19 and 0.13% (P=0.035) in Periods 1, 2 and 3, respectively. The numbers of resistant strains among those acquired during hospitalization were 12 in Period 1, four in Period 2 and six in Period 3. Long-term intranasal mupirocin treatment in MRSA carrier patients with long hospital stay is associated with a decrease in acquired carriage and MRSA infections, while resistance of the strains to mupirocin does not increase provided that colonized patients are only treated once.     

Methicillin-resistant Staphylococcus aureus in veterinary doctors and students, the Netherlands

The prevalence of methicillin-resistant Staphylococcus aureus (MRSA) in the Netherlands, at 1.0%, is among the lowest in Europe. In 2004, a relationship between pig farming and a high risk for MRSA carriage was found. To investigate if those in professional contact with livestock are at higher risk for MRSA carriage, we screened 80 veterinary students and 99 veterinarians and questioned them about animal contacts and known MRSA risk factors. Of these, 27 students who did not have livestock contact were excluded from further analysis. We found 7 carriers of MRSA, a prevalence of 4.6%, which is similar to that found in patients who had previously been treated at foreign hospitals. A correlation of MRSA carriage with a specific animal group could not be established. To preserve the low prevalence of MRSA in the Netherlands, persons involved in the care of livestock should be isolated and screened on admission to the hospital.     

Risk factors for Staphylococcus aureus nasal carriage in residents of three nursing homes in Germany

The prevalence of Staphylococcus aureus nasal carriage in three nursing homes (N=500) was 36.6%. No meticillin-resistant S. aureus (MRSA) was detected. The following significant risk factors for S. aureus nasal carriage were identified: vascular cognitive impairment [odds ratio (OR)=0.31]; diabetes mellitus (OR=1.82); hypertension (OR=0.30); chronic obstructive pulmonary disease (OR=1.86); stroke (OR=3.31); antibiotic therapy within the previous three months (OR=2.10); and level 2 care (defined as highly dependent, needing help in activities of daily living for up to 4h/day) (OR=1.97). Compared with other countries, the prevalence of MRSA nasal carriage in residents of German nursing homes is low.