Internet queries and methicillin-resistant Staphylococcus aureus surveillance

The Internet is a common source of medical information and has created novel surveillance opportunities. We assessed the potential for Internet-based surveillance of methicillin-resistant Staphylococcus aureus and examined the extent to which it reflects trends in hospitalizations and news coverage. Google queries were a useful predictor of hospitalizations for methicillin-resistant S. aureus infections.     

Isolate removal methods and methicillin-resistant Staphylococcus aureus surveillance

The effect of duplicate isolate removal strategies on Staphylococcal aureus susceptibility to oxacillin was compared by using antimicrobial test results for 14,595 isolates from statewide surveillance in Hawaii in 2002. No removal was compared to most resistant and most susceptible methods at 365 days and to the National Committee for Clinical Laboratory Standards (NCCLS) and Cerner algorithms at 3-, 10-, 30-, 90-, and 365-day analysis periods. Overall, no removal produced the lowest estimates of susceptibility. Estimates with either NCCLS or Cerner differed by <2% when the analysis period was the same; with either method, the difference observed between a 90- and a 365-day period was <1%. The effect of duplicate isolate removal was greater for inpatient than outpatient settings. Considering the ease of implementation and comparability of results, we recommend using the first isolate of a given species per patient to calculate susceptibility frequencies for S. aureus to oxacillin.     

National hospital infection surveillance on methicillin-resistant Staphylococcus aureus

Surveillance of methicillin-resistant Staphylococcus aureus (MRSA) infections in Japan was performed in 1995 and 1996. Hospital infection rates of MRSA appear to have remained stable in recent years, and this study was undertaken to test this hypothesis. In national surveillance, the incidence of MRSA hospital infections per 100 admissions remained stable at between 0.7 and 0.8 from 1999 to 2003, with a tendency towards a slight decline. This study shows that precautions against MRSA infection in Japan may prove to be an effective preventive measure.     

Development of a surveillance system for methicillin-resistant Staphylococcus aureus in German hospitals.

OBJECTIVE: To determine the appropriate method to calculate the rate of methicillin-resistant Staphylococcus aureus (MRSA) infection and colonization (hereafter, MRSA rates) for interhospital comparisons, such that the large number of patients who are already MRSA positive on admission is taken into account. DESIGN: A prospective, multicenter, hospital-based surveillance of MRSA-positive case patients from January through December 2004. SETTING: Data from 31 hospitals participating in the German national nosocomial infections surveillance system (KISS) were recorded during routine surveillance by the infection control team at each hospital. RESULTS: Data for 4,215 MRSA-positive case patients were evaluated. From this data, the following values were calculated. The median incidence density was 0.71 MRSA-positive case patients per 1,000 patient-days, and the median nosocomial incidence density was 0.27 patients with nosocomial MRSA infection or colonization per 1,000 patient-days (95% CI, 0.18-0.34). The median average daily MRSA burden was 1.13 MRSA patient-days per 100 patient-days (95% CI, 0.86-1.51), with the average daily MRSA burden defined as the total number of MRSA patient-days divided by the total number of patient-days times 100. The median MRSA-days-associated nosocomial MRSA infection and colonization rate, which describes the MRSA infection risk for other patients in hospitals housing large numbers of MRSA-positive patients and/or many patients who were MRSA positive on admission, was 23.1 cases of nosocomial MRSA infection and colonization per 1,000 MRSA patient-days (95% CI, 17.4-28.6). The values were also calculated for various MRSA screening levels. CONCLUSIONS: The MRSA-days-associated nosocomial MRSA rate allows investigators to assess the extent of MRSA colonization and infection at each hospital, taking into account cases that have been imported from other hospitals, as well as from the community. This information provides an appropriate incentive for hospitals to introduce further infection control measures.     

Osteomyelitis with methicillin-resistant Staphylococcus aureus

We describe 10 patients with hospital-acquired osteomyelitis due to methicillin-resistant Staphylococcus aureus. The patients were posttraumatic and eight had a foreign body in situ at the site of infection. Vancomycin therapy in association with radical debridement was followed by clinical and radiological cure in eight patients at 2-3.5 years follow-up, in two of whom a foreign body was left in situ. Only minor adverse effects of vancomycin therapy (one rash, two thrombophlebitis) were seen.     

Screening strategies in surveillance and control of methicillin-resistant Staphylococcus aureus (MRSA)

With reports of hospital-acquired methicillin-resistant Staphylococcus aureus (MRSA) continuing to increase and therapeutic options decrease, infection control methods are of increasing importance. Here we investigate the relationship between surveillance and infection control. Surveillance plays two roles with respect to control: it allows detection of infected/colonized individuals necessary for their removal from the general population, and it allows quantification of control success. We develop a stochastic model of MRSA transmission dynamics exploring the effects of two screening strategies in an epidemic setting: random and on admission. We consider both hospital and community populations and include control and surveillance in a single framework. Random screening was more efficient at hospital surveillance and allowed nosocomial control, which also prevented epidemic behaviour in the community. Therefore, random screening was the more effective control strategy for both the hospital and community populations in this setting. Surveillance strategies have significant impact on both ascertainment of infection prevalence and its control.     

Molecular epidemiology of methicillin-resistant Staphylococcus aureus

Subtyping methicillin- resistant Staphylococcus aureus (MRSA) isolates and tracking nosocomial infections have evolved from phenotypic to genotypic approaches; most laboratories now depend on pulsed-field gel electrophoresis (PFGE). We discuss the limitations of current image-based genotyping methods, including PFGE, and the advantages (including ease of entering data into a database) of using DNA sequence analysis to control MRSA infections in health-care facilities.     

Human-to-dog transmission of methicillin-resistant Staphylococcus aureus

Methicillin-resistant Staphylococcus aureus (MRSA) was cultured from the nose of a healthy dog whose owner was colonized with MRSA while she worked in a Dutch nursing home. Pulsed-field gel electrophoresis and typing of the staphylococcal chromosome cassette mec (SCCmec) region showed that both MRSA strains were identical.     

Genetic characterization of methicillin-resistant Staphylococcus aureus

The genome structure of Staphylococcus aureus is analyzed. The genome is composed of two domains. The first domain, descendent from an ancestral bacterial species, contains house-keeping genes that showed highest homology to those of Bacillus species. The second domain contained the genes responsible for virulence and drug-resistance in human infection that seems to have been acquired from other bacterial species via lateral gene transfer. The latter domain constitutes the genetic information that makes S. aureus a notorious hospital pathogen.     

耐甲氧西林金黄色葡萄球菌的目标性监控与分析

目的 了解临床耐甲氧西林金黄色葡萄球菌的分离及耐药性,探索耐甲氧西林金黄色葡萄球菌感染病例的监控措施.方法 对2010年医院临床分离的病原菌进行目标性监测,统计出耐甲氧西林金黄色葡萄球菌的株数以及耐药性,并对临床耐甲氧西林金黄色葡萄球菌感染病例实施监控.结果 全年检测结果发现,共分离出金黄色葡萄球菌334株,耐甲氧西林金黄色葡萄球菌50株,检出率为14.97％;对抗菌药物耐药率较高;全院未发生耐甲氧西林金黄色葡萄球菌的暴发和流行.结论 耐甲氧西林金黄色葡萄球菌分离株数较多,耐药率较高,应该加强临床合理使用抗菌药物的管理,并对耐甲氧西林金黄色葡萄球菌感染病例实施监控,预防和减少多药耐药菌的产生,控制医院感染.     

Effect of targeted surveillance for control of methicillin-resistant Staphylococcus aureus in a community hospital system.

OBJECTIVE: To examine the cost associated with targeted surveillance for methicillin-resistant Staphylococcus aureus (MRSA) and the effect of such surveillance on the rate of nosocomial MRSA infection in a community hospital system. DESIGN: A before-and-after study comparing the rate of MRSA infection before (BES) and after (AES) the initiation of expanded surveillance. Cost-effectiveness was calculated as the difference between the cost savings associated with preventing nosocomial MRSA bacteremias and surgical site infections AES and the cost of MRSA cultures and contact isolation for patients colonized with MRSA. SETTING AND PARTICIPANTS: Patients in a 400-bed tertiary-care facility (Roper Hospital) and a 180-bed suburban hospital (St. Francis Hospital), both in Charleston, South Carolina.Interventions. Beginning in September 2001, patients were screened for MRSA colonization upon admission to the intensive care unit and weekly thereafter. In July 2002, surveillance was expanded to include targeted screening of patients admitted to general wards who were at risk of MRSA colonization. Colonized patients were placed in contact isolation. RESULTS: The mean rate of nosocomial MRSA infection decreased at Roper (0.76 cases per 1,000 patient-days BES and 0.45 per 1000 patient-days AES; P = .05) and at St. Francis (0.73 cases per 1,000 patient-days BES and 0.57 cases per 1000 patient-days AES; P=.35). Surveillance was cost-effective, preventing 13 nosocomial MRSA bacteremias and 9 surgical site infections, for a savings of 1,545,762 US dollars. CONCLUSIONS: Targeted surveillance for MRSA colonization was cost-effective and provided substantial benefits by reducing the rate of nosocomial MRSA infections in a community hospital system.     

耐甲氧西林金黄色葡萄球菌的耐药性分析

目的 了解耐甲氧西林金黄色葡萄球菌临床感染现状及其耐药性,为临床合理使用抗菌药物提供科学依据.方法 采用phonix-100对314株金黄色葡萄球菌进行鉴定和药敏试验,数据统计使用WHONET5.5软件及SPSS17.0软件进行.结果 共分离出314株金黄色葡萄球菌,其中耐甲氧西林金黄色葡萄球菌(MRSA) 164株,占52.2％,甲氧西林敏感金黄色葡萄球菌(MSSA) 150株,占47.8％;标本来源以痰液为主,占58.3％,其次是伤口分泌物占29.3％;MRSA和MSSA对万古霉素、替考拉宁、利奈唑胺无耐药,MRSA对阿米卡星、庆大霉素、妥布霉素、利福平、环丙沙星、磺胺甲噁唑/甲氧苄啶、克林霉素、红霉素、四环素耐药率分别为86.6％、89.6％、93.3％、43.3％、87.8％、6.7％、84.1％、84.1％、85.3％;MSSA对青霉素、阿米卡星、庆大霉素、妥布霉素、利福平、环丙沙星、磺胺甲噁唑/甲氧苄啶、克林霉素、红霉素、四环素耐药率分别为92.0％、0.7％、32.7％、32.7％、2.7％、10.0％、34.7％、36.0％、59.3％、22.0％;MRSA对大环内酯类、氨基糖苷类、氟喹诺酮类、四环素类、克林霉素耐药率明显高于MSSA.结论 MRSA分离率较高,耐药性严重,应引起重视,临床应根据药敏试验结果合理选择抗菌药物.