耐甲氧西林金黄色葡萄球菌感染的治疗研究进展

随着耐甲氧西林金黄色葡萄球菌(MRSA)的感染率不断增加,并成为全球院内感染的首要致病菌。因其高感染率、高致死率以及多重耐药株的出现,使临床治疗面临极大的挑战。本文将从药物治疗、噬菌体疗法和免疫防治等方法对耐甲氧西林金黄色葡萄球菌感染的治疗进行综述,以期对该病原菌临床治疗提供一定的参考。     

Community-associated methicillin-resistant Staphylococcus aureus: current status and molecular epidemiological perspective

MRSA has been a major causative agent of nosocomial infection. However, recently MRSA has become increasingly isolated from community-associated infections. We summarized here up to date information about community-associated MRSA (C-MRSA) infections and characteristics of C-MRSA strains based on molecular analysis. By using the SCCmec typing, strong evidence was provided for the independent derivation of healthcare-associated MRSA and C-MRSA clones.     

Community-associated methicillin-resistant Staphylococcus aureus endocarditis 'down under': case series and literature review

Infective endocarditis is a common complication of Staphylococcus aureus bacteraemia, but literature reports of community-associated methicillin-resistant S. aureus (CA-MRSA) endocarditis are relatively uncommon and mostly comprise intravenous drug users (IVDUs) with the USA300 strain. We report 5 cases of CA-MRSA endocarditis in previously healthy young Australian adults, 4 in IVDUs. Morbidity was high with frequent septic emboli; 3 patients required cardiac surgery and 1 patient died. Typing revealed the 2 most common Australian strains, the Panton-Valentine leukocidin (PVL)-positive ST93 (Queensland) strain and the PVL-negative ST1 (WA-MRSA-1) strain.     

Community-associated methicillin-resistant Staphylococcus aureus skin infections: advances toward identifying the key virulence factors

PURPOSE OF REVIEW: In recent years there has been an increase in the incidence of community-associated methicillin-resistant Staphylococcus aureus (CA-MRSA) infections in healthy individuals, the cause of which is largely unknown. CA-MRSA primarily causes skin and soft-tissue infections but certain strains are also associated with unusually severe pathology. The purpose of this review is to provide a critical analysis of our current knowledge of virulence factors contributing to skin and soft-tissue infections caused by CA-MRSA. RECENT FINDINGS: Isolates classified as pulsed-field gel electrophoresis type USA300 have emerged as the predominant CA-MRSA genotype and in most geographic areas account for 97% or more of CA-MRSA infections. Recent key studies, such as those reporting the complete genome sequence of USA300, and the discovery of cytolytic peptides that contribute significantly to CA-MRSA virulence, lead the way for future investigations. SUMMARY: Although we have only a cursory understanding of the molecular mechanisms of CA-MRSA virulence, studies using clinically relevant CA-MRSA isolates are beginning to identify virulence determinants specific to this pathogen. Identifying CA-MRSA virulence determinants and the concerted regulation of these factors will foster development of vaccines and therapeutics designed to control CA-MRSA skin infections.     

Community-associated methicillin-resistant Staphylococcus aureus in a pediatric emergency department in Newfoundland and Labrador

BACKGROUND:

First-generation cephalosporins and antistaphylococcal penicillins are typically the first choice for treating skin and soft tissue infections (SSTI), but are not effective for infections caused by methicillin-resistant Staphylococcus aureus (MRSA). It is currently unclear what percentage of SSTIs is caused by community-associated MRSA in different regions in Canada.

OBJECTIVES:

To determine the incidence of MRSA in children presenting to a pediatric emergency department with SSTI, and to determine which antibiotics were used to treat these infections.

METHODS:

All visits to a pediatric emergency department were reviewed from April 15, 2010 to April 14, 2011. Diagnoses of cellulitis, abscess, impetigo, folliculitis and skin infection (not otherwise specified) were reviewed in detail to determine whether a culture was taken and which antibiotic was prescribed.

RESULTS:

There were 367 cases of SSTI diagnosed over the study period. Forty-five (12.3%) patients had lesions that were swabbed for culture and sensitivity. S aureus was the most common organism found, with 14 (66%) methicillin-sensitive cases and seven (33%) methicillin-resistant cases. Of the seven cases of MRSA identified, only one patient had clear risk factors for hospital-acquired MRSA. First-generation cephalosporins were initially prescribed for 280 (76%) patients.

CONCLUSIONS:

The overall incidence of MRSA in the population presenting to a pediatric emergency department in Newfoundland and Labrador appeared to be low, although only a small percentage of infections were cultured. At this time, there appears to be no need to change empirical antibiotic coverage, which remains a first-generation cephalosporin.     

Community-associated methicillin-resistant Staphylococcus aureus necrotizing pneumonia without evidence of antecedent viral upper respiratory infection

BACKGROUND:

USA300 community-associated (CA) methicillin-resistant Staphylococcus aureus (MRSA) strains causing necrotizing pneumonia have been reported in association with antecedent viral upper respiratory tract infections (URI).

METHODS:

A case series of necrotizing pneumonia presenting as a primary or coprimary infection, secondary to CA-MRSA without evidence of antecedent viral URI, is presented. Cases were identified through the infectious diseases consultation service records. Clinical and radiographic data were collected by chart review and electronic records. MRSA strains were isolated from sputum, bronchoalveolar lavage, pleural fluid or blood cultures and confirmed using standard laboratory procedures. MRSA strains were characterized by susceptibility testing, pulsed-field gel electrophoresis, spa typing, agr typing and multilocus sequence typing. Testing for respiratory viruses was performed by appropriate serological testing of banked sera, or nucleic acid testing of nasopharyngeal or bronchoalveloar lavage specimens.

RESULTS:

Ten patients who presented or copresented with CA necrotizing pneumonia secondary to CA-MRSA from April 2004 to October 2011 were identified. The median length of stay was 22.5 days. Mortality was 20.0%. Classical risk factors for CA-MRSA were identified in seven of 10 (70.0%) cases. Chest tube placement occurred in seven of 10 patients with empyema. None of the patients had historical evidence of antecedent URI. In eight of 10 patients, serological or nucleic acid testing testing revealed no evidence of acute viral coinfection. Eight strains were CMRSA-10 (USA300). The remaining two strains were a USA300 genetically related strain and a USA1100 strain.

CONCLUSION:

Pneumonia secondary to CA-MRSA can occur in the absence of an antecedent URI. Infections due to CA-MRSA are associated with significant morbidity and mortality. Clinicians need to have an awareness of this clinical entity, particularly in patients who are in risk groups that predispose to exposure to this bacterium.     

Community-associated methicillin-resistant Staphylococcus aureus in northwest Ontario: A five-year report of incidence and antibiotic resistance

BACKGROUND:

The incidence of community-associated methicillin-resistant Staphylococcus aureus (CA-MRSA) is traditionally high in remote areas of Canada with large Aboriginal populations. Northwestern Ontario is home to 28,000 First Nations people in more than 30 remote communities; rates of CA-MRSA are unknown.

OBJECTIVE:

To determine the CA-MRSA rates and antibiotic susceptibilities in this region.

METHODS:

A five-year review of laboratory and patient CA-MRSA data and antibiotic susceptibility was undertaken.

RESULTS:

In 2012, 56% of S aureus isolates were CA-MRSA strains, an increase from 31% in 2008 (P=0.06). Reinfection rates have been increasing faster than new cases and, currrently, 25% of infections are reinfections. CA-MRSA isolates continue to be susceptible to many common antibiotics (nearly 100%), particularly trimethoprim/sulfamethoxazole, clindamycin and tetracycline. Erythromycin susceptibility stands at 58%.

DISCUSSION:

Rates of CA-MRSA, as a percentage of all S aureus isolates, were higher than those reported in other primary care series. The infection rate per 100,000 is one the highest reported in Canada. Antibiotic susceptibilities were unchanged during the study period; the 99% susceptibility rate to clindamycin differs from a 2010 Vancouver (British Columbia) study that reported only a 79% susceptibility to this antibiotic.

CONCLUSION:

There are very high rates of CA-MRSA infections in northwestern Ontario. Disease surveillance and ongoing attention to antibiotic resistance is important in understanding the changing profile of MRSA infections. Social determinants of health, specifically improved housing and sanitation, remain important regional issues.     

Community-associated methicillin-resistant Staphylococcus aureus infections in men who have sex with men: A case series

BACKGROUND: The purpose of the present study was to describe the clinical characteristics and management of community-associated methicillin-resistant Staphylococcus aureus (CA-MRSA) infections among a cohort of men who have sex with men. PATIENTS AND METHODS: A retrospective chart review was conducted of patients with culture-proven MRSA at Maple Leaf Medical Clinic (Toronto, Ontario) between November 2004 and December 2005. Cases were identified by individual physicians and by queries in the clinical management system. A standard data collection form was used to record patient demographics, potential risk factors for MRSA and course of illness. When available, antimicrobial sensitivities were recorded. DNA fingerprinting using pulsed-field gel electrophoresis, and genetic analysis for SCCmec typing and detection of the Panton-Valentine leukocidin cytotoxin were performed on six available isolates. RESULTS: Seventeen patients with MRSA infection were identified, 12 (71%) of whom were HIV-positive. The most common clinical presentation was abscess (35%), followed by furuncle (17%), folliculitis (17%), cellulitis (17%) and sinusitis (12%). The majority of MRSA isolates were resistant to ciprofloxacin (92%) and levofloxacin (77%). All isolates were susceptible to trimethoprim-sulfamethoxazole, rifampin, linezolid, gentamicin and clindamycin, while the majority were susceptible to tetracycline (80%). All six isolates tested were SCCmec type IVa-positive and Panton-Valentine leukocidin-positive, and had fingerprint patterns consistent with the CMRSA-10 (USA300) clone. CONCLUSION: The present study describes the clinical presentation and management of CA-MRSA infections occurring in Toronto among men who have sex with men. The infections appear to have been caused by CMRSA-10, which has caused the majority of CA-MRSA outbreaks elsewhere.     

社区获得性耐甲氧西林金黄色葡萄球菌

社区获得性耐甲氧西林金黄色葡萄球菌是社区感染中重要的致病菌之一,以往由其所致感染多发生在医院环境,如今其引起的社区感染的比例不断上升.自1961年发现第1株耐甲氧西林金黄色葡萄球菌以来,耐甲氧西林金黄色葡萄球菌在世界各地流行并引起暴发流行,耐药程度不断加重.尤其1996年万古霉素不敏感金黄色葡萄球菌及2002年耐万古霉素金黄色葡萄球菌的出现,显示其对人类的威胁愈趋严重,已成为当今感染医学一个难题.本文介绍社区获得性耐甲氧西林金黄色葡萄球菌的流行情况及防治措施.     

Control of methicillin-resistant Staphylococcus aureus

Methicillin-resistant Staphylococcus aureus (MRSA) is a leading cause of nosocomial infections worldwide. Different approaches to the control of this pathogen have met with varying degrees of success in different health care settings. Controversies exist with regards to various MRSA control strategies. The implementation and outcomes of control measures depend on several factors, including scientific, economic, administrative, governmental, and political influences. It is clear that flexibility to adapt and institute these measures in the context of local epidemiology and resources is required.     

Staphylococcus aureus methicillin-resistant: emergence and dissemination

Nosocomial infections due to methicillin-resistant Staphylococcus aureus (MRSA) is an important health problem worldwide. This microorganism causes a variety of clinical infections, including osteomyelitis, invasive endocarditis, septic arthritis and septicemia. Antimicrobial resistance is a factor that influences the persistence of MRSA in the hospital environment. The introduction of molecular typing techniques in epidemiological investigations has provided new tools for identifying the microorganism's origin and routes of dissemination. One of the most important conclusions that have resulted from these types of studies is that a small number of clones are responsible for most of the staphylococcal infections throughout the world.     

Community-acquired methicillin-resistant Staphylococcus aureus pneumonia

Community-acquired methicillin-resistant Staphylococcus aureus is increasingly recognized as an important pathogen causing skin and soft tissue infections. We report a case of severe necrotizing pneumonia caused by community-acquired methicillin-resistant S. aureus in a peripartum woman. This case illustrates that community-acquired methicillin-resistant S. aureus must be considered as a potential pathogen in severe community-acquired pneumonia.