Tea tree oil as an alternative topical decolonization agent for methicillin-resistant Staphylococcus aureus

The combination of a 4% tea tree oil nasal ointment and 5% tea tree oil body wash was compared with a standard 2% mupirocin nasal ointment and triclosan body wash for the eradication of methicillin-resistant Staphylococcus aureus carriage. The tea tree oil combination appeared to perform better than the standard combination, although the difference was not statistically significant due to the small number of patients.     

Importance of bacterial burden among methicillin-resistant Staphylococcus aureus carriers in a long-term care facility.

OBJECTIVE: To evaluate the prevalence and transmission of methicillin-resistant Staphylococcus aureus (MRSA) nasal colonization, as well as risk factors associated with MRSA carriage, among residents of a long-term care facility (LTCF). DESIGN: Prospective, longitudinal cohort study. SETTING: A 100-bed Veterans Administration LTCF. PARTICIPANTS: All current and newly admitted residents of the LTCF during an 8-week study period. METHODS: Nasal swab samples were obtained weekly and cultured on MRSA-selective media, and the cultures were graded for growth on a semiquantitative scale from 0 (no growth) to 6 (heavy growth). Epidemiologic data for the periods before and during the study were collected to assess risk factors for MRSA carriage. RESULTS: Of 83 LTCF residents, 49 (59%) had 1 or more nasal swab cultures that were positive for MRSA; 34 (41%) were consistently culture-negative (designated "noncarriers"). Of the 49 culture-positive residents, 30 (36% of the total of 83 residents) had all cultures positive for MRSA (designated "persistent carriers"), and 19 (23% of the 83 residents) had at least 1 culture, but not all cultures, positive for MRSA (designated "intermittent carriers"). Multivariate analysis showed that participants with at least 1 nasal swab culture positive for MRSA were likely to have had previous hospitalization (odds ratio, 3.9) or wounds (odds ratio, 8.2). Persistent carriers and intermittent carriers did not differ in epidemiologic characteristics but did differ in mean MRSA growth score (3.7 vs 0.7; P<.001). CONCLUSIONS: Epidemiologic characteristics differed between noncarriers and subjects with at least 1 nasal swab culture positive for MRSA. However, in this LTCF population, only the degree of bacterial colonization (as reflected by mean MRSA growth score) distinguished persistent carriers from intermittent carriers. Understanding the burden of colonization may be important when determining future surveillance and control strategies.     

Mupirocin-resistant, methicillin-resistant Staphylococcus aureus: does mupirocin remain effective?

OBJECTIVE: To determine the efficacy of mupirocin ointment in reducing nasal colonization with mupirocin-susceptible, methicillin-resistant Staphylococcus aureus (MS MRSA) as well as mupirocin-resistant MRSA (MR MRSA). DESIGN: Prospective evaluation in which patients colonized with MRSA were treated twice daily with 2% topical mupirocin ointment for 5 days. SETTING: James H. Quillen Veterans' Affairs Medical Center. PATIENTS: Forty hospitalized patients with two anterior nares cultures positive for MRSA within a 7-day period. METHODS: Treated patients had post-treatment cultures at day 3 and weeks 1, 2, and 4. Isolates underwent mupirocin-susceptibility testing and DNA typing. MRSA clearance and type turnover were assessed for isolates that were mupirocin-susceptible, low-level (LL) MR MRSA and high-level (HL) MR MRSA. RESULTS: Post-treatment nares cultures on day 3 were negative for 78.5%, 80%, and 27.7% of patients with MS MRSA, LL-MR MRSA, and HLMR MRSA, respectively. Sustained culture negativity at 1 to 4 weeks was more common in the MS MRSA group (91%) than in the LL-MR MRSA group (25%) or the HL-MR MRSA group (25%). Positive post-treatment cultures usually showed the same DNA pattern relative to baseline. Plasmid curing of 18 HL-MR MRSA resulted in 15 MS MRSA and 3 LL-MR MRSA. CONCLUSIONS: Mupirocin was effective in eradicating MS MRSA, but strains of MR MRSA often persisted after treatment. This appeared to reflect treatment failure rather than exogenous recolonization. MR MRSA is now more prevalent and it is appropriate to sample MRSA populations for mupirocin susceptibility prior to incorporating mupirocin into infection control programs.     

Current practice in Staphylococcus aureus screening and decolonization

We surveyed infectious disease physicians to determine their preoperative Staphylococcus aureus screening and decolonization practices. Sixty percent reported preoperative screening for S. aureus. However, specific screening and decolonization practices are highly variable, are focused almost exclusively on methicillin-resistant S. aureus, and do not include testing for mupirocin or chlorhexidine resistance.     

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.     

Phages for methicillin-resistant Staphylococcus aureus: an international trial.

An internationally agreed and validated set of phages is used worldwide for the typing of strains of Staphylococcus aureus of human origin. However, because of the sometimes reduced susceptibility of methicillin-resistant strains (MRSA) to these phages, some of the national typing centres use locally isolated and characterized sets of experimental phages. In this trial, 42 such phages were distributed to 6 centres and tested against 744 isolates of MRSA with the intention of defining a phage set to augment the international set. The use of these experimental phages increased the percentage typability from 75% with the international set to 93% and the number of identifiable lytic patterns from 192 to 424. A subset of 10 experimental phages was selected. When this subset was compared with the experimental panel, the typability rate was 91% and 370 distinct patterns were obtained. This subset of phages has been distributed for international trial.     

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.     

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.     

A model for surveillance of methicillin-resistant Staphylococcus aureus

It is well recognized that methicillin-resistant Staphylococcus aureus (MRSA) has become a community pathogen. Several key differences between community-associated and hospital-associated MRSA strains exist, including distinct methicillin resistance genes and genetic backgrounds and differing susceptibility to antibiotics. Recent studies have demonstrated that typical hospital and community strains easily move between hospital and community environments. Despite evidence of MRSA's expanding reach in the community, the best methods for population-level detection and containment have not been established. In an effort to determine effective methods for monitoring the spread of MRSA, we reviewed the literature on hospital-associated and community-associated MRSA (CA-MRSA) in the community and proposed a model for enhanced surveillance. By linking epidemiologic and molecular techniques within a surveillance system that coordinates activities in the community and health-care setting, scientists and public health officials can begin to measure the true extent of CA-MRSA in communities and hospitals.     

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.     

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.     

Control of epidemic methicillin-resistant Staphylococcus aureus

We controlled the spread of epidemic methicillin-resistant Staphylococcus aureus (MRSA) infection in an 884-bed veterans' facility by cohorting known active MRSA carriers and MRSA-infected patients on one nursing unit. Simultaneously, all previously-institutionalized transfers into the veterans' facility were screened with swab cultures for MRSA at the time of admission. All MRSA patients were maintained on contact (gown and glove) or strict isolation and treated aggressively with topical and enteral antibiotics with the assistance of the infectious disease consultant. The monthly incidence of new MRSA patients dropped from a maximum of 16 per month to three or less per month within six months of instituting these infection control measures. There were no further MRSA bacteremias after the establishment of the MRSA cohort in a single unit. Aggressive cohort management of known MRSA patients and screening of previously-institutionalized patients on admission for MRSA controlled epidemic MRSA in this large institution.