Household transmission of meticillin-resistant Staphylococcus aureus and other staphylococci

Although the role of pets in household transmission of meticillin-resistant Staphylococcus aureus (MRSA) has been examined previously, only minor attention has been given to the role of the abiotic household environment independent of, or in combination with, colonisation of pets and human beings to maintain transmission cycles of MRSA within the household. This report reviews published work about household transmission of S aureus and other staphylococci and describes contamination of household environmental surfaces and colonisation of pets and people. Household microbial communities might have a role in transfer of antimicrobial resistance genes and could be reservoirs for recolonisation of people, although additional research is needed regarding strategies for decontamination of household environments. Household-based interventions should be developed to control recurrent S aureus infections in the community, and coordination between medical and veterinary providers could be beneficial.     

Community-acquired meticillin-resistant Staphylococcus aureus: an emerging threat

Community-acquired meticillin-resistant Staphylococcus aureus (MRSA) is becoming an important public-health problem. New strains of S aureus displaying unique combinations of virulence factors and resistance traits have been associated with high morbidity and mortality in the community. Outbreaks of epidemic furunculosis and cases of severe invasive pulmonary infections in young, otherwise healthy people have been particularly noteworthy. We review the characteristics of these new strains of community-acquired MRSA that have contributed to their pathogenicity and discuss new approaches to the diagnosis and management of suspected and confirmed community-acquired MRSA infections.     

Postoperative infection with meticillin-resistant Staphylococcus aureus and socioeconomic background

Infectious disease can be linked to social deprivation. We investigated whether postoperative infection with meticillin-resistant Staphylococcus aureus (MRSA) is related to socioeconomic background. Patients were stratified by social deprivation according to postcode. In a consecutive series of 1739 UK residents undergoing isolated coronary artery bypass grafting, 23 (1.3%) were infected with MRSA. We noted a graded relation between incidence of infection and social deprivation. Patients from the most deprived areas had a seven-fold higher infection rate (13 of 579 [2.2%]) than those from the least deprived areas (two of 580 [0.3%]; p=0.0040). Patients with MRSA infection had a six-fold higher mortality rate and a longer hospital stay than patients with no such infection. Our findings suggest that patients from deprived areas might be especially susceptible to postoperative infection with MRSA.     

Effect of vancomycin and rifampicin on meticillin-resistant Staphylococcus aureus biofilms

Decolonisation of patients with urinary catheter colonisation by meticillin-resistant Staphylococcus aureus (MRSA) is often difficult. Replacement of the catheter after prophylactic vancomycin administration has been one approach that is often unsuccessful in clinical practice. We suspected that formation of MRSA biofilms might account for the persistence of infection, and our study confirms this, also showing that MRSA is able to colonise a silastic rubber surface even in the presence of prophylactic vancomycin or rifampicin.     

Emergence and resurgence of meticillin-resistant Staphylococcus aureus as a public-health threat

Staphylococcus aureus is a gram-positive bacterium that colonises the skin and is present in the anterior nares in about 25-30% of healthy people. Dependent on its intrinsic virulence or the ability of the host to contain its opportunistic behaviour, S aureus can cause a range of diseases in man. The bacterium readily acquires resistance against all classes of antibiotics by one of two distinct mechanisms: mutation of an existing bacterial gene or horizontal transfer of a resistance gene from another bacterium. Several mobile genetic elements carrying exogenous antibiotic resistance genes might mediate resistance acquisition. Of all the resistance traits S aureus has acquired since the introduction of antimicrobial chemotherapy in the 1930s, meticillin resistance is clinically the most important, since a single genetic element confers resistance to the most commonly prescribed class of antimicrobials--the beta-lactam antibiotics, which include penicillins, cephalosporins, and carbapenems.     

Importance of the environment in meticillin-resistant Staphylococcus aureus acquisition: the case for hospital cleaning

In the UK, we continue to debate the importance of hospital cleaning in relation to increasing numbers of patients acquiring meticillin-resistant Staphylococcus aureus (MRSA). However, there is little direct evidence for the effectiveness of cleaning because it has never been afforded scientific status. Hospital hygiene is usually assessed visually, but this does not necessarily correlate with microbiological risk. A more robust case for hospital cleaning can be presented by considering the evidence for all the stages of the staphylococcal transmission cycle between human beings and their environment. Cleaning has already been accepted as an important factor in the control of other hardy environmental pathogens, such as Clostridium difficile, vancomycin-resistant enterococci, norovirus, and Acinetobacter spp. This Review will show why the removal of dirt might have more impact on the control of MRSA than previously thought. Introduction of additional cleaning services is easier than improvements in hand-hygiene compliance.     

耐甲氧西林金黄色葡萄球菌检出动态及对万古霉素的耐药性变迁

目的 观察耐甲氧西林金黄色葡萄球菌(MRSA)在临床标本中的检出动态及对万古霉素的耐药性变化趋势。方法 检测1966年～2001年各年度各种临床标本中MRSAR的分离率，测量万古霉素对MRSA的抑菌环直径大小。结果 1996～2000年5年内MRSA检出率有逐年上升趋势，2001年通过筛查MRSA携带者并采取消毒隔离措施后，2001年MRSA检出率为32．1％，与2000年(45．9％)、1999年检出率(38．5％)比较明显降低，与1998年(30．2％)接近。随着时间推移，各年度MRSA对万古霉素的抑菌圈直径逐年减小。结论 通过筛查MRSA携带者并采取严格的消毒隔离措施，可使MRSA的检出率下降。MRSA对万古霉素的敏感程度在逐年降低。     

Secrets of success of a human pathogen: molecular evolution of pandemic clones of meticillin-resistant Staphylococcus aureus

The first European isolate of meticillin-resistant Staphylococcus aureus (MRSA) was detected in 1960. Since then MRSA has become a leading cause of nosocomial infections worldwide. Using molecular typing techniques--primarily pulsed-field gel electrophoresis (PFGE)--we identified five major MRSA clones that accounted for almost 70% of the over 3000 MRSA isolates recovered in hospitals mainly in southern and eastern Europe, South America, and the USA. Most of our surveillance studies were done in these areas. Multilocus sequencing typing (MLST) of representative isolates of this collection showed that these five pandemic MRSA clones have evolved from only two distinct ancestral genetic backgrounds, one of which can be traced back to the very first European MRSA isolates and also to meticillin susceptible S aureus strains circulating in Danish hospitals during the mid to late 1950s--i.e., shortly before the introduction of meticillin into therapy. The second lineage with a completely different MLST profile included MRSA frequently recovered in the USA, Japan, and among paediatric isolates from several parts of the world. A few isolates with a third distinct MLST type corresponding to that of EMRSA-16 were also detected in the early Danish isolates. The four structural types of mec element, the heterologous DNA segment containing the meticillin resistance determinant mecA, were present in unique combinations with the MRSA clonal types. Our findings establish evolutionary associations in the most widely spread pandemic clones of MRSA. The epidemiological factors that contributed to the massive dissemination of a few MRSA clones are not well understood. We suggest, however, that the secrets of effectiveness of MRSA could be hidden in the unique genetic background of a surprisingly few lineages of S aureus particularly well able to cope with the contemporary clinical environment.     

利奈唑胺对高龄男性耐甲氧西林金黄色葡萄球菌患者血液生理指标影响及安全性分析

目的：观察利奈唑胺对耐甲氧西林金黄色葡萄球菌（MRSA）感染的高龄男性患者血液生理指标及安全性的影响。方法选取2012年4月至2013年3月在解放军总医院住院并确诊MRSA感染的46例高龄男性患者（83～95岁）,均给予利奈唑胺注射液治疗,0.6g、1次/12h,疗程10～14d。比较治疗前后红细胞（RBC）、血红蛋白（HB）、白细胞（WBC）、血小板（PLT）和网织红细胞（Ret）等血液生理指标变化。观察治疗期间出血不良反应。结果治疗后与治疗前比较,HB[（95.609±14.210） vs （102.478±15.941）g/L]、WBC＆#215;1012/L [（6.944±2.590） vs （8.728±2.277）]、Ret[（1.124%±0.844%） vs （1.789%±0.831%）]和PLT＆#215;109/L [（142.913±62.065） vs （227.304±56.250）]均显著降低,差异均有统计学意义（P＜0.01）。治疗期间共有22例患者发生出血倾向,出现2个部位出血患者10例（22%）,3个部位出血患者4例（9%）,≥4个部位出血患者2例。结论利奈唑胺能降低高龄男性患者HB、PLT、Ret水平,治疗期间需警惕出血并发症。