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.     

Suffering from meticillin-resistant Staphylococcus aureus: experiences and understandings of colonisation

The objective was to explore individuals' experiences and understandings of meticillin-resistant Staphylococcus aureus (MRSA) colonisation. Thirteen interviews were performed and processed using content analysis, resulting in the theme ‘Invaded, insecure and alone’. The participants experienced fears and limitations in everyday life and expressed a need to protect others from contagion. Moreover, they experienced encounters with, and information from, healthcare workers differently: some were content, whereas others were discontent. The described fears, limitations and inadequate professional–patient relationship generated unacceptable distress for MRSA-colonised persons. Thus, the healthcare sector should assume responsibility for managing MRSA, and healthcare workers must improve their professionalism and information skills, so as to better meet MRSA-colonised persons' needs.     

定植压力与耐甲氧西林金黄色葡萄球菌医院内交叉传播相关性研究

目的了解医院环境耐甲氧西林金黄色葡萄球菌(MRSA)的分布、耐药性和分子分型情况,为医院感染防控提供依据。方法对2014年12月—2015年5月上海市静安区某三级综合性医院监护病房环境中分离的MRSA菌株,采用K-B纸片扩散法进行药敏试验,并采用脉冲场凝胶电泳(PFGE)进行分子分型。结果316件标本中检出金黄色葡萄球菌46株,污染率为14.6%;检出MRSA22株,污染率为7.0%。MRSA对头孢呋辛、左氧氟沙星、环丙沙星、氨苄西林/舒巴坦、红霉素、庆大霉素的耐药率均高于甲氧西林敏感的金黄色葡萄球菌(MSSA),差异均有统计学意义(P值均＜0.01)。14株MRSA经PFGE检测后共分为8个型别,总体相似度在85%的水平。其中2个型别各有4株为同一基因型。结论医院环境表面分离的MRSA对β-内酰胺类、喹诺酮类、大环内酯类抗生素存在不同程度耐药,环境中存在MRSA克隆株污染,应加强病人和环境、医务人员和环境之间的感染控制措施。     

UK healthcare workers' knowledge of meticillin-resistant Staphylococcus aureus practice guidelines; a questionnaire study

Effective infection control practice requires knowledge of and adherence to contemporary infection control guidelines. Utilising a novel questionnaire tool, we evaluated knowledge of recently published guidelines on meticillin-resistant Staphylococcus aureus (MRSA) precautions in a number of relevant healthcare worker (HCW) populations. The questionnaire was developed from national UK MRSA practice guidelines and consisted of 10 ‘true or false’ statements. The questionnaire was utilised to assess knowledge in 293 participants from HCW and control populations. The participants included 188 doctors attending the British Medical Association's Annual Representatives Meeting, 52 trainee surgeons attending the Association of Surgeons in Training annual conference, 30 members of a non-clinical control population and 23 infection control nurses (ICNs). The mean (SD) score for knowledge levels obtained from doctors was 6.6 (1.68), for non-clinical control population was 4.7 (1.8) and for ICNs, 8.4 (1.12). There were significant differences in knowledge levels between different population groups (P < 0.001), UK employment region of the participant (P = 0.01) and the doctors' medical specialty (P = 0.02). Career seniority and gender of the participant were not significantly associated with differences in levels of knowledge. This questionnaire study evaluates a novel discriminatory questionnaire tool which differentiates knowledge levels of MRSA practice guidelines among a non-clinical population, HCWs and specialist infection control staff, thus providing a means for the rapid assessment of MRSA educational interventions. We identify demographics within HCW target populations which are associated with low levels of such knowledge. Consideration towards revising current HCW educational programmes to improve knowledge and best practice in MRSA prevention is required.     

Survey of meticillin-resistant Staphylococcus aureus policies in UK eye departments

The purpose of this study was to investigate meticillin-resistant Staphylococcus aureus (MRSA) screening and decolonisation practices for patients undergoing routine cataract surgery in ophthalmology departments across the UK. A postal questionnaire survey of all ophthalmology departments in the UK was carried out, with 75 of 152 (49.3%) questionnaires returned. Sixty-three percent of units had a departmental MRSA policy. Preoperative MRSA screening was performed in 50 (66.7%) units, three of which screened all preoperative patients and the remainder performed selective screening. The proportion of patients screened for MRSA ranged from 0 to 100%, with a median of 2% and a mean of 9.9% (95% confidence interval: 3.5–16.2%). Overall, 65.3% of respondents felt that their departmental policy was reasonable, although there was considerable dissatisfaction and confusion, with comments identifying lack of evidence and the need for guidelines applicable to day-case cataract surgery. The survey demonstrates significant inconsistencies in preoperative MRSA screening practice in ophthalmology departments throughout the UK. Current recommendations from the Department of Health suggest that day-case ophthalmology patients do not require routine screening, although the implication appears that high risk patients continue to do so. Further investigation is required to ascertain the scientific validity of these recommendations.     

The evolution of Staphylococcus aureus

A broad variety of infections, ranging from minor infections of the skin to post-operative wound infections can be caused by Staphylococcus aureus. The adaptive power of S. aureus to antibiotics leaded, in the early 1960s, to the emergence of methicillin-resistant S. aureus (MRSA). The cause of resistance to methicillin and all other β-lactam antibiotics is the mecA gene, which is situated on a mobile genetic element, the staphylococcal cassette chromosome mec (SCCmec). Seven major variants of SCCmec, type I to VII, are distinguished. The most important techniques used to investigate the molecular epidemiology of S. aureus are pulsed-field gel electrophoresis (PFGE), multilocus sequence typing (MLST), S. aureus protein A (spa) typing and SCCmec typing (only for MRSA). These techniques have been used to study the evolution of the MRSA clones that have emerged since the early 1960s, and to study their subsequent worldwide dissemination. The early MRSA clones were hospital-associated (HA-MRSA). However, from the late 1990s, community-associated MRSA (CA-MRSA) clones emerged worldwide. CA-MRSA harbors SCCmec type IV, V or VII, the majority belong to other S. aureus lineages compared to HA-MRSA, and CA-MRSA is often associated with the presence of the toxin Panton-Valentine leukocidin (PVL). However, during recent years, the distinction between HA-MRSA and CA-MRSA has started to disappear, and CA-MRSA is now endemic in many US hospitals. MRSA probably originated trough the transfer of SCCmec into a limited number of methicillin-sensitive S. aureus (MSSA) lineages. This review describes the latest observations about the structure of SCCmec, the techniques used to study the molecular epidemiology and evolution of S. aureus as well as some challenges that researchers face in the future.     

Beneficial effects of dietary arginine supplementation in methicillin-resistant Staphylococcus aureus infected mice

To determine any potential benefits of feeding increased amounts of arginine to septic mice, 45 BALB/c mice were randomized into 3 groups. Group A mice were fed 20% casein diet (control), whereas the mice in Groups B and C were given 20% casein diet supplemented with 2% and 4% arginine, respectively. The diets were isonitrogenous and isocaloric. On the 10th day on these diets, each mouse was challenged with 2.0×10⁸ colony forming units (CFU) of methicillin-resistant Staphylococcus aureus (MRSA) organisms intravenously and mortality noted for 20 days. The final survival rate in Group A (20%) tended to be lower than the rates in Group B (60%) and Group C (46%) but without significant difference (p>0.05). Of the surviving mice 20 days post inoculation, in Group B, 7 out of 9 (77%) eliminated the organisms as compared to 1 out of 4 (25%) in Group A, and 3 out of 7 (43%) in Group C. The surviving mice in Group B had significantly heavier splenic weight (140±30mg) as compared to Group A mice (90±10mg). The present data suggest that 2% dietary arginine supplementation may be beneficial in offering protection to the mice following MRSA challenge.     

Methicillin-resistant Staphylococcus aureus (MRSA) isolated in clinics and hospitals in the Fukuoka city area

Bacteriological and clinical studies were carried out on 280 strains of Staphylococcus aureus isolated in clinics and hospitals in the Fukuoka city area from September 1990 to March 1991. The percentage of methicillin-resistant S. aureus (MRSA) strains studied was 41·4% (116 of 280). Of 116 MRSA strains, 48 (41·3%) produced coagulase VII and 21 (18·1%) produced coagulase II. The mean age of the patients who harboured MRSA, 70·5 ± 16·9 years, was significantly higher than that of patients with methicillin-sensitive S. aureus (MSSA), 44·2 ± 29·3 years (P < 0·001). MRSA was detected more frequently than MSSA in sputum (P < 0 · 01), while MSSA was detected more frequently than MRSA in pus (P < 0 · 01). Ninety (89 · 1%) of 101 strains of MRSA were isolated from inpatients and 98 (71 · 0%) of 130 strains of MSSA were isolated from outpatients. Similar number of MRSA strains were recovered in a variety of hospitals, indicating that there was no relationship between hospital size (number of beds) and the incidence of MRSA. As for drug susceptibility, coagulase VII-producing MRSA strains were more sensitive to clindamycin (P < 0 · 01) and more resistant to mino-cycline (P < 0 · 01) than were other MRSA strains.     

Eradication of the long-term carriage of methicillin-resistant Staphylococcus aureus in patients wearing dentures: a follow-up of 10 patients

To cure the long-term carriage of methicillin-resistant Staphylococcus aureus (MRSA), eradication treatment was given to 10 patients wearing complete dentures. In addition to multiple body sites, MRSA was cultured from the dentures of six patients. The contaminated dentures were rebased and sterilized with heat in order to prevent recolonization. The patients did not use their dentures during the decolonization therapy. Subsequently, MRSA was eradicated from three of these patients but three others remained MRSA-positive despite at least two courses of combined systemic and topical eradication treatment. These particular patients had persistent stomatitis and their dentures were a poor fit, in poor condition and repeatedly grew MRSA. Eradication treatment was successful in the remaining four patients whose dentures were MRSA-negative. These results confirm that dentures may function as foreign bodies and sustain persistent nasopharyngeal.MRSA colonization. Therefore, we suggest that whenever eradication of MRSA is deemed necessary in cases of nasal, oral or pharyngeal carriage, heat treatment of the dentures should be included. Further comparative studies with larger patient populations are needed to evaluate the contribution of dentures to the long-term carriage of MRSA, as well as to assess the value of denture sterilization during the eradication course.     

Limited effectiveness of chlorhexidine based hand disinfectants against methicillin-resistant Staphylococcus aureus (MRSA)

Hand disinfectants containing chlorhexidine are thought to be less bactericidal against methicillin-resistant Staphylococcus aureus (MRSA) than methicilhn-susceptible Staphylococcus aureus (MSSA). We report an in vitro comparison between three distinct MRSA strains and three MSSA strains. The bactericidal efficacy of chlorhexidine digluconate, ‘Hibiscrub’ and ‘Hibisol’ against Staphylococcus aureus was determined in a quantitative suspension test. Logarithmic reduction factors (RF) were calculated for each of six parallel experiments. Chlorhexidine digluconate and ‘Hibisol’ showed RF>5 at most concentrations and reaction times but ‘Hibiscrub’ did not. MRSA was found to be significantly less susceptible than MSSA to chlorhexidine digluconate, ‘Hibiscrub’ and ‘Hibisol’ (P < 0·05; two-tailed t-test for independent samples). ‘Hibisol’ was significantly more effective against MRSA than ‘Hibiscrub’ (P < 0·05). Hand disinfectants containing both alcohol and chlorhexidine (e.g., ‘Hibisol’) are more effective against MRSA than scrubs based only on chlorhexidine (‘Hibiscrub’) and should be used in clinical practice.     

我国食品来源金黄色葡萄球菌种群结构分析

目的了解我国食源性金黄色葡萄球菌(金葡菌)的种群结构。方法通过全基因组测序方法对2006-2020年我国16个省份收集的763株食源性金葡菌进行多位点序列分型、葡萄球菌蛋白A编码基因(spa)和葡萄球菌染色体mec基因盒(SCCmec)分型, 使用BioNumerics 7.5软件创建基于ST类型的最小生成树。国外进口食品分离到的金葡菌31株被纳入基因组系统发育树的构建。结果 763株金葡菌共鉴定出90个ST型和160个spa型别, 其中20种为新ST型别。72个(72/90, 80.0%)ST型属于22个克隆群, 其中主要型别为CC7、CC1、CC5、CC398、CC188、CC59、CC6、CC88、CC15和CC25, 占82.44%(629/763)。其中优势克隆群中ST型和spa型别随着时间的变化呈多态性变化。耐甲氧西林金葡菌(MRSA)的阳性率为7.60%, 共鉴定出7种SCCmec型别, 以ST59-t437-Ⅳa(17.24%, 10/58)、ST239-t030-Ⅲ(12.07%, 7/58)、ST59-t437-Ⅴb(8.62%, 5/58)、ST338-t437-...     

Methicillin-resistant Staphylococcus aureus (MRSA) and Pseudomonas aeruginosa isolation from pharyngeal swab cultures among the Japanese elderly at admission to a geriatric hospital

The isolation rate of Methicillin-resistant Staphylococcus aureus (MRSA) and Pseudomonas aeruginosa from pharyngeal swab cultures in the Japanese elderly was studied at admission to a geriatric hospital which had long-term care units. The subjects were 233 consecutive patients who were admitted to K Hospital in the time period April 1994 to March 1996. The isolation rate of MRSA and of Pseudomonas aeruginosa was 10.3% and 8.2% respectively. The proportions of the patients with severely to moderately limited Activities of Daily Living (ADL) (ADL score = 0–1) (P < 0.01), those with fever (P < ;0.01), those with CRP positive (P = 0.04) and those with hypoalbuminemia (serum albumin<3.5 g/dl) (P < 0.01) were higher in the MRSA positive patients than in the negative patients while the proportion of the patients with fever was higher in the Pseudomonas aeruginosa positive patients than in the negative patients (P < 0.02). In the multiple logistic regression analysis, the limitation of ADL (ADL score 0–1 vs 2–3, OR = 1.54, 95% CI = 1.02–2.33) and fever (with vs without, OR = 1.77, 95% CI = 1.18–2.66) remained as risk factors for the isolation of MRSA while only fever (with vs without, OR = 1.67, 95% CI = 1.11–2.53) remained as a risk factor for the isolation of Pseudomonas aeruginosa.     

Staff carriage of methicillin-resistant Staphylococcus aureus (EMRSA 15) and the home environment: a case report

A case of refractory carriage of methicillin-resistant Staphylococcus aureus (MRSA) by a nurse is described. The nurse's home environment was widely contaminated with MRSA and two family members acquired the organism. Relapse of carriage after routine anti-staphylococcal measures and three negative sets of screening specimens resulted in a hospital outbreak involving three patients. The problem was finally terminated after a co-ordinated commercial cleaning of the house, thermal disinfection of all linen and replacement of some soft furnishings.     

Multiple-locus variable-number tandem-repeat analysis of meticillin-resistant Staphylococcus aureus discriminates within USA pulsed-field gel electrophoresis types

Many isolates of meticillin-resistant Staphylococcus aureus (MRSA) are indistinguishable when compared using the standard pulsed-field gel electrophoresis (PFGE) typing method. This may present a problem when investigating local outbreaks of MRSA transmission in a healthcare setting. It also impedes investigation of the widely disseminated community-acquired MRSA (USA 300-0114) in the inpatient setting, which is displacing other traditional hospital-acquired PFGE types. Combination of methods, including multiple-locus sequence typing (MLST), spa typing and staphylococcal cassette chromosome mec (SCCmec) typing, have been used with, or in place of, PFGE to characterise MRSA for epidemiological purposes. These methods are technically challenging, time-consuming and expensive and are rarely feasible except in large laboratories in tertiary care medical centres. Another method, which is simpler and with faster turnaround time, is multiple-locus variable-number tandem-repeat analysis (MLVA). We investigated the utility of MLVA to distinguish common PFGE types. The results suggest that MLVA can be used to identify unrelated strains with identical PFGE patterns or confirm close genetic composition of linked isolates. MLVA could potentially be used in conjunction with PFGE to validate relationships, but further prospective evaluation of these relationships will be required in order to define the proper role, if any, for use of this method in hospital epidemiology.     

Trends in sources of meticillin-resistant Staphylococcus aureus (MRSA) bacteraemia: data from the national mandatory surveillance of MRSA bacteraemia in England, 2006–2009

The national mandatory surveillance system for reporting meticillin-resistant Staphylococcus aureus (MRSA) bacteraemia in England has captured data on the source of reported bacteraemias since 2006. This study analysed episodes of MRSA bacteraemia (N = 4404) where a probable source of infection was reported between 2006 and 2009. In 2009, this information was available for one-third of reported episodes of MRSA bacteraemia. Of these, 20% were attributed to intravascular devices and 28% were attributed to skin and soft tissue infection. Sixty-four percent of the patients were male, and urinary tract infection was a significantly more common source of MRSA bacteraemia in males compared with females (12% vs 3%). Detection of bacteraemia within two days of hospital admission does not reliably discriminate between community- and hospital-associated MRSA bacteraemia as community cases are frequently associated with an invasive procedure/device. Between 2006 and 2009, there was a significant decline in the proportion of episodes of MRSA bacteraemia associated with central vascular catheters [incidence rate ratio (IRR) 0.42, 95% confidence interval (CI) 0.29–0.61; P < 0.001], peripheral vascular catheters (IRR 0.69, 95% CI 0.48–0.99; P = 0.042) and surgical site infection (IRR 0.42, 95% CI 0.25–0.72; P = 0.001), and a significant increase in the proportion of episodes of MRSA bacteraemia associated with skin and soft tissue infection (IRR 1.33, 95% CI 1.05–1.69; P = 0.017) and attributed to contamination of the specimen (IRR 1.96, 95% CI 1.25–3.06; P = 0.003). Since data were not available for all cases, the generalizability of these trends depends on the assumption that records with source data reflect a reasonably random sample of cases in each year. These changes have occurred in the context of a general decline in the rate of MRSA bacteraemia in England since 2006.     

N-terminal sequence polymorphism in the coagulase gene of Staphylococcus aureus and its potential use as an epidemiological marker

N-terminal DNA sequences of the coagulase gene were amplified from Staphylococcus aureus strain ISP8 (NCTC 8325-4) DNA using the polymerase chain reaction. The amplified DNA product (984 bp) was used to probe SmaI and DraI digested total DNA of methicillin- and multi-resistant S. aureus (MRSA) type strains, methicillin-sensitive S. aureus (MSSA) clinical isolates, and community (commensal) isolates. A SmaI fragment of a similar size in all the isolates examined hybridized with the coagulase gene fragment probe. All MRSA isolates, representing closely related (clonal) types, revealed identical coagulase hybridization patterns with DraI digested DNA. MSSA and community isolates closely related to ISP8 by SmaI fragment analysis shared closely related DraI/coagulase hybridization patterns, differing from that identified for the MRSAs. In contrast, the community and MSSA isolates not related to ISP8 as judged by total SmaI fragment polymorphisms, were also diverse in their DraI/ coagulase hybridization patterns. In addition, the intensity of the hybridization signal obtained with the MRSA isolates varied significantly (less than) from the other isolates, indicating the presence of multiple and probably different coagulase genes between the isolates. The findings reported here indicate that hybridization analysis using single genes as DNA probes is less discriminant than restriction fragment length polymorphism analysis of the total genome of different isolates.