Community-onset healthcare-associated MRSA bacteraemia in a district general hospital

Methicillin-resistant Staphylococcus aureus (MRSA) bacteraemia is associated with significant mortality and morbidity. This retrospective study involved 76 episodes over four years in a district general hospital in the UK. Twenty-eight of these episodes (36.8%) occurred within 72 h of admission. All of these, however, had risk factors for MRSA acquisition and were classified as healthcare-associated bacteraemias. The mortality rates (all causes) at seven days and three months were 31.5% and 53.4%, respectively. Ten patients died before targeted therapy could be commenced. All patients in the study had multiple comorbidities, and pneumonia was a common diagnosis. Previous antibiotics, increased age, admission on surgical wards/intensive care units, and the presence of central venous cannulae and urinary catheters were risk factors for infection. In 48.7% of episodes, patients were not known to be colonized with MRSA prior to their bacteraemia. Empirical targeted therapy should be given to patients with risk factors for MRSA and staphylococci in blood cultures pending susceptibility results. Increased use of screening may also be required to reduce transmission and increase the likelihood of appropriate empirical antimicrobial therapy. Eradication of MRSA from carriers in the community should be considered to reduce the number of community-onset healthcare-associated bacteraemias.     

Enhanced surveillance of meticillin-resistant Staphylococcus aureus bacteraemia in a London teaching hospital

In 2001, the UK Department of Health introduced mandatory surveillance of meticillin-resistant Staphylococcus aureus (MRSA) bacteraemias (blood-culture-positive episodes) in English hospitals. We performed enhanced surveillance in their hospital between April 2001 and March 2003 to determine the epidemiology of MRSA bacteraemia across different specialities. There were 267 MRSA-blood-culture-positive episodes, giving a rate of 0.37 per 1000 occupied bed-days (OBD). Thirty-three (12.4%) episodes were false positives due to contaminants and 15 (5.6%) originated in the community or at another institution. Thirty-one (11.6%) episodes were in outpatients or occurred after recent discharge and were designated 'hospital associated'. The remaining 188 cases were clinically significant hospital-acquired episodes in inpatients, with a rate of 0.26 per 1000 OBDs. The highest rates were in the intensive therapy unit (ITU; 2.74 per 1000 OBDs) and the high-dependency unit (HDU; 1.68 per 1000 OBDs). Fifty-five non-ITU, non-HDU episodes occurred in patients who had been discharged from ITU or HDU prior to the development of bacteraemia but during the same admission. The number of MRSA bacteraemias related to ITU/HDU suggests that these wards may be hubs of MRSA infection. Haematology, oncology and renal (HOR) patients had the greatest number of hospital-associated episodes. The most common source of MRSA bacteraemia was a vascular access device (VAD) (108 episodes, 57%, 64% of which were central lines). The high bacteraemia rates in ITU, HDU and HOR patients were associated with high usage of VADs. The majority of episodes occurred in patients who were newly colonized with MRSA after admission. Thus, in this hospital, VADs and stays in ITU or HDU are important risk factors for bacteraemia, and VAD care and prevention of cross-infection are priorities for intervention. We recommend that the mandatory national surveillance scheme should collect additional data on MRSA bacteraemia to provide information for a national strategy for MRSA control and to allow appropriate comparison between institutions.     

Random meticillin-resistant Staphylococcus aureus carrier surveillance at a district hospital and the impact of interventions to reduce endemic carriage

Colonisation with meticillin-resistant Staphylococcus aureus (MRSA) has previously been described as a risk factor for subsequent infection. MRSA colonisation reached endemic proportions in most healthcare institutions in the UK during the 1990s. Bacteraemia due to MRSA is associated with increased mortality and morbidity compared with meticillin-susceptible S. aureus and national targets have been set for reduction. We present our findings of regular random colonisation surveillance and systematic decolonisation of MRSA carriers over a five-year period with the aim of reducing the pool of carriers and number of MRSA bacteraemia cases. Interventions to reduce the rate of colonisation included assurance of decolonisation and follow up, targeting wards with the highest carriage rates using enhanced screening and education, and screening all admissions aged >65 years. There was a statistically significant reduction in the proportion of patients colonised from 14.6% to 7.0% (P < 0.001) and the total number of bacteraemia cases from 42 to 22 (P = 0.012) in the initial 24 months of surveillance compared to the most recent 24 months. Regular surveillance of MRSA carriage is useful for monitoring the effects of control measures on MRSA carriage among inpatients. Interventions to reduce carriage are able to reduce the pool of MRSA carriers, thereby reducing cases of bacteraemia.     

Appearance of methicillin-resistant Staphylococcus aureus (MRSA) sensitive to gentamicin in a hospital with a previous endemic distinct MRSA

Since 1990 a clone of gentamicin and methicillin-resistant Staphylococcus aureus (MRSA) has remained endemic in our hospital, but since January 1996 a gentamicin-sensitive strain has progressively replaced the previous clone. We characterized the phenotypic and molecular pattern of the MRSA strains isolated in our hospital in 1996 and compared prospectively the epidemiological, clinical and evolutionary characteristics of ninety patients infected or colonized by gentamicin-sensitive MRSA (GS-MRSA) (49) and by gentamicin-resistant MRSA (GR-MRSA) (41). Finally we studied the variation of aminoglycoside consumption in our hospital from 1989 to 1996. We observed two antibiotypes (GS-MRSA and GR-MRSA) corresponding to two major chromosomal patterns. Patients with GS-MRSA usually acquired the infection 72 hours after hospital admission. No significant differences were observed in epidemiological characteristics, clinical presentation and evolution between patients with GS-MRSA and GR-MRSA. Since 1989 aminoglycoside intake in our hospital has decreased by 46%.     

Molecular characterization of methicillin-resistant Staphylococcus aureus (MRSA) in a university hospital in Italy

The molecular epidemiology of methicillin-resistant Staphylococcus aureus (MRSA) in a university hospital in Italy was studied in a five-month period in 1996, during which all S. aureus isolated were collected. All MRSA isolates (95) and a sample of methicillin-susceptible S. aureus (20) were typed with a variety of phenotypic and genotypic methods. Clonal identities were determined by pulsed-field gel electrophoresis (PFGE) of chromosomal SmaI digests and, for MRSA isolates, by probing ClaI digests with a mecA probe and a Tn554 probe. Overall, MRSA represented 32.3% of all isolates, with very high percentages from the intensive care units (adult and neonatal). PFGE after restriction with SmaI resolved genomic DNA of 95 MRSA strains into 26 major PFGE patterns. The use of southern blot hybridization of ClaI genomic digests with mecA and Tn554 allowed us a significant increase in discrimination, differentiating at least 32 different clones. Two major clones, however, each sharing common ClaI-mecA and Tn554 type and PFGE pattern as well as a common resistance phenotype, represented more than 50% of all MRSA isolates. The recovery of these two clones in the majority of the isolates of adult and neonatal intensive care units, respectively, is indicative of typical nosocomial outbreaks and clonal spread. It is concluded that intensive care units are major areas requiring preventative interventions.     

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.     

三级教学医院综合ICU导管相关性感染的目标性监测

目的了解综合ICU患者导管相关性感染的现状及特点,为制定预防控制方案提供依据。方法根据目标性监测要求,对2012年1-12月ICU患者的医院感染发病率、3种导管相关感染及常见病原菌特点进行监测,采用MINKE医院感染管理软件系统对监测资料进行汇总分析。结果 814例ICU住院时间>48h的患者,发生医院感染74例次、例次感染率为9.09%,例次千日感染率为11.50‰,调整后日例次感染率为3.87‰;3种导管相关性感染率以呼吸机相关性感染居首位,千日感染率为22.72‰,留置尿管和中心静脉置管相关性感染次之,分别为1.94‰和1.47‰;共分离病原菌103株,其中革兰阴性菌79株占76.70%,革兰阳性菌11株占10.68%,真菌13株占12.62%;ICU医院感染检出的主要病原菌耐药现象严重,其中金黄色葡萄球菌对万古霉素和利奈唑胺保持全敏感,真菌对伏立康唑、伊曲康唑和两性霉素B均敏感,肠杆菌科细菌对亚胺培南、美罗培南、头孢替坦、阿米卡星等抗菌药物保持较高的敏感性。结论 3种导管的使用率和感染率与国内统计数据相仿,但是呼吸机相关性肺炎(VAP)的发生率远高于美国国家医疗安全网络(NHSN)统计数据,需重点加强预防VAP干预措施的制定。     

Risk factors for methicillin-resistant staphylococcus aureus (MRSA) infection in a Japanese geriatric hospital

A case control study on MRSA infection was carried out, with the purpose of evaluating the effect of age, gender, hypoalbuminemia, the limitation of activities of daily living (ADL), the administration of antibiotics and the use of the new cephems which include third generation cephalosporins and monobactam and carbapenems, on the occurrence of MRSA infection among the inpatients in a geriatric hospital. From April 1991 to March 1994, 285 patients underwent a bacterial culture in the various clinical aspects. 118 patients were positive for MRSA, who were then used as cases while 167 patients who were negative for MRSA were used as controls. The level of serum albumin and the ADL score were lower in the MRSA group than in the non-MRSA group (P < 0.01) while the number of antibiotics administered before bacterial culture was greater in the MRSA group than in the non-MRSA group (P < 0.01). The third generation cephems were more commonly used in the MRSA positive patients than the negative patients (P < 0.01). Even after controlling for the other factors, hypoalbuminemia (OR = 1.73, 95% CI = 1.27–2.36), the limited ADL (partially limited vs without limitation: OR = 1.88, 95% CI = 1.19–2.96, completely limited vs without limitation: OR = 2.50, 95% CI = 1.64–3.82), the use of antibiotics other than the third generation cephems (vs without antibiotics: OR = 1.73, 95% CI = 1.20–2.50) and the administration of the third generation cephems (vs without antibiotics: OR = 3.12, 95% CI = 2.16–4.50) increased the risk of MRSA infection.     

Distribution of erm genes among MRSA isolates with resistance to clindamycin in a Chinese teaching hospital

The objective of this study was to analyze erythromycin and clindamycin resistance patterns among different MRSA lineages in China. Antimicrobial susceptibility testing, resistance determinant screening, plasmid electroporation and sequence comparisons were performed. High rates of clindamycin (92.5%, 270/292) and erythromycin (92.8%, 271/292) resistance were observed. Additionally, 88.2% (60/68) of the ST59 MRSA isolates and 78.9% (15/19) of the ST239 MRSA isolates had constitutive resistance to clindamycin, while 82.0% (123/150) of the ST5 MRSA isolates showed inducible clindamycin resistance. The ermB gene was identified in 80.9% (55/68) of the ST59 isolates but was not detected in ST5 and ST239 MRSA isolates. Detection rates of ermA were high in the ST5 (99.3%, 149/150) and ST239 (89.5%, 17/19) MRSA isolates, but no ermA-positive ST59 MRSA isolates were identified. The ermC gene, observed to be harbored on similar, transmissible plasmids ranging in size from 2402 to 2473 bp, were found in different MRSA lineages. Summarily, high erythromycin and clindamycin resistance rates were observed in MRSA isolates. ST59 and ST239 MRSA isolates primarily exhibited constitutive resistance, while ST5 MRSA isolates showed inducible resistance phenotypes. ermA and ermB genes were frequently carried by specific MRSA clones, while ermC gene was present within small transmissible plasmids in all lineages. Erythromycin and clindamycin resistance genes transfer between MRSA isolates in healthcare settings remains a problem, and infection control procedures should be applied.     

替考拉宁与万古霉素治疗MRSA下呼吸道感染的疗效与安全性评价

目的 评价替考拉宁与万古霉素治疗下呼吸道耐甲氧西林金黄色葡萄球菌(MRSA)感染的疗效和安全性.方法 对28例应用替考拉宁和32例应用万古霉素治疗的MRSA肺部感染患者进行治疗前后的临床症状、体征、临床疗效、细菌清除情况以及不良反应的统计分析,并将临床分离菌分别进行替考拉宁和万古霉素的体外药敏试验.结果 替考拉宁与万古霉素治疗MRSA肺部感染的临床有效率为75.00%和78.13%,细菌清除率为78.51%和84.38%,不良反应总发生率为10.71%和15.63%,两组结果 差异无统计学意义;平均治疗时间为替考拉宁组(9.29±3.77)d,万古霉素组(15.13±9.28)d,差异有统计学意义(P＜0.01);万古霉素和替考拉宁对两组患者痰培养所得的60株MRSA均敏感;另外,两组均有少数患者出现一过性肝功能升高;各有1例白细胞下降,停药后好转,万古霉素组有1例发生急性肾功能衰竭.结论 替考拉宁治疗MRSA下呼吸道感染疗效较好,且安全可靠;替考拉宁较之万古霉素使用时间更短.     

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.     

2008-2010年北京某综合医院医院感染监测资料分析

目的 总结和分析某综合医院医院感染发生率、病死率和病原菌的分布.方法 利用北京市《医院感染监控管理系统》收集2008-2010年的医院感染监测数据,对所收集的数据进行描述性统计分析,并对计数资料进行卡方检验.结果 3年发生医院感染649例,感染率为0.79％;感染部位构成以下呼吸道感染为主占43.6％,其次为手术部位感染占19.2％,泌尿道感染占8.2％,皮肤软组织感染占7.3％;检出病原菌共560株,构成主要为革兰阴性杆菌占52.7％,其次为真菌占25.0％,革兰阳性球菌占21.4％;与医院感染有关死亡病例40例,病死率为6.16％,医院感染与非医院感染病例病死率相比相对危险度(RR)为8.27.结论 某综合医院医院感染发生率总体水平较低且呈现下降趋势,实施有效的感染控制措施利于预防与控制医院感染的发生.     

溃疡膏加白糖治疗烧伤创面耐甲氧西林金黄色葡萄球菌感染疗效观察

目的观察溃疡膏加白糖在治疗烧伤耐甲氧西林金黄色葡萄球菌(MRSA)感染创面的临床效果,缩短残余创面治愈时间。方法回顾性总结1996年1月~2008年10月收治的烧伤患者,创面分泌物细菌培养为MRSA感染者52例,创面处理在溃疡膏内加入白糖,创面用约1∶5000高锰酸钾溶液清洗干净,直接涂抹溃疡膏后覆盖凡士林纱布,半暴露或者干纱布包扎,根据创面感染控制情况每日或者间隔1~2 d换药1次。结果经过2~5次换药,感染创面1周内很快得到控制,MRSA检出阳性率从用药前的100.00%下降至用药后1周的5.76%;无新生感染创面,治愈40例,12例创面较大者换药控制感染后手术植皮治愈,所有创面在1~2周内痊愈。结论溃疡膏加白糖治疗烧伤创面MRSA感染,具有明显的抗菌作用,能加速创面愈合,临床效果满意,方法简单可行,值得临床推广应用。     

A change in Belgian epidemic methicillin-resistant Staphylococcus aureus phage types in 2000: phenotypic and genotypic characterization of isolates from a general hospital

During 2000, new methicillin-resistant Staphylococcus aureus (MRSA) epidemic phage types became preponderant in Belgium. In the present study, phenotypic and genotypic characteristics of 130 MRSA isolates from a general Belgian hospital were investigated. The MRSA nature of the isolates was confirmed by coagulase test, oxacillin screen plate test and detection of the mecA gene by polymerase chain reaction. Phage typing categorized the MRSA strains into two main groups: the [O]* types and the [J]* types. SmaI macrorestriction analysis by pulsed-field gel electrophoresis gave the same pulsotype in the majority of strains. All strains of the [O]* and [J]* groups, except one, belonged to this pulsotype. Aminoglycoside-modifying-enzyme genes could only be detected in a minority of strains. Although the epidemic phage types of the mid-1990s appear to have been supplanted by the [O]* and [J]* groups, the MRSA population examined showed a remarkably uniform profile corresponding to the previous major clone B.     

Analysis of surveillance data with Poisson regression: a case study

One way to examine the ability of a statistical technique to detect changes in surveillance data is to analyse data sets with known changes and observe how accurately these changes can be detected. The elimination of restrictions on legal abortions should have reduced mortality associated with abortions, particularly mortality associated with illegal abortions. The sensitivity of Poisson regression to detect changes in abortion associated mortality from 1962 to 1984 was assessed for the entire United States of America and for specific states. Although it is clear that this change occurred using data from the entire United States, only the largest of the individual state data sets examined (370 events over 23 years) consistently demonstrated the expected pattern. Inconsistent patterns were found in data sets from two states with between one-fourth and one-half this number of events. The legal change was not detected at all in three states with a small number of events (1 event per year or less). From this case study, a minimum of two or three events per year seems to be necessary before Poisson regression can detect outliers. Comparisons of the four tests used suggest that tests based on model deviance are superior to tests based on comparison of observed and expected number of events.     

Hypothetical performance of syndrome-based management of acute paediatric admissions of children aged more than 60 days in a Kenyan district hospital

OBJECTIVE: To investigate whether the outpatient, syndrome-based approach of the Integrated Management of Childhood Illness (IMCI) protocol could be extended to the inpatient arena to give clear and simple minimum standards of care for poorly resourced facilities. METHODS: A prospective, one-year admission cohort retrospectively compared hypothetical performance of syndrome-based management with paediatrician-defined final diagnosis. Admission syndrome definitions were based on local adaptations to the IMCI protocol that encompassed 20 clinical features, measurement of oxygen saturation, and malaria microscopy. FINDINGS: After 315 children with clinically obvious diagnoses (e.g. sickle cell disease and burns) were excluded, 3705 admission episodes were studied. Of these, 2334 (63%) met criteria for at least one severe syndrome (mortality 8% vs <1% for "non-severe" cases), and half of these had features of two or more severe syndromes. No cases of measles were seen. Syndrome-based treatment would have been appropriate (sensitivity >95%) for severe pneumonia, severe malaria, and diarrhoea with severe dehydration, and probably for severe malnutrition (sensitivity 71%). Syndrome-directed treatment suggested the use of broad-spectrum antibiotics in 75/133 (56% sensitivity) children with bacteraemic and 63/71 (89% sensitivity) children with meningitis. CONCLUSIONS: Twenty clinical features, oxygen saturation measurements, and results of malaria blood slides could be used for inpatient, syndrome-based management of acute paediatric admissions. The addition of microscopy of the cerebrospinal fluid and haemoglobin measurements would improve syndrome-directed treatment considerably. This approach might rationalize admission policy and standardize inpatient paediatric care in resource-poor countries, although the clinical detection of bacteraemia remains a problem.