烧伤病人耐甲氧西林金黄色葡萄球菌及其肠毒素的检测和耐药性分析

目的:评价乳胶结合实验,检测重症监护病房(ICU)耐甲氧西林金黄色葡萄球菌(MRSA)及其肠毒素(SE),并进行耐药性分析。方法:收集260株金黄色葡萄球菌临床分离株,通过药敏试验将其分为耐甲氧西林金黄色葡萄球菌和甲氧西林敏感金黄色葡萄球菌(MSSA),用反向间接血凝试验(RPHA)检测金黄色葡萄球菌肠毒素。结果:MRSA产肠毒素为134株,MSSA产肠毒素为38株,MRSA产肠毒素率为100％,MSSA产肠毒素率为30％。结论:重症监护病房应重视MRSA的检测和金黄色葡萄球菌肠毒素的检测,合理使用广谱抗菌药物。     

Methicillin-resistant Staphylococcus aureus: investigation of a hospital outbreak using a case-control study

A retrospective case-control study of 50 MRSA-positive patients was carried out during an outbreak of methicillin-resistant Staphylococcus aureus (MRSA) at an acute general hospital in London. Controls were randomly selected from MRSA-negative patients admitted during the outbreak period. Risk factors investigated included length of admission prior to screening, number of ward changes, main diagnosis, extent of staff contact, pressure sores, surgical and other invasive procedures and antibiotic treatment. Outcome variables examined were rates of infection (versus colonization) with MRSA and mortality. Patients with MRSA were in hospital longer before microbiological specimens were taken and moved wards more often than controls. In a logistic regression analysis, length of stay in hospital, pressure sores, physiotherapy and surgical procedures were associated with a significantly increased risk of acquiring MRSA. Odds ratios (and 95% confidence intervals) for having acquired MRSA were: 8·3 (1·02−71·43) if a patient had pressure sores; 3·7 (1·10−12·5) if they received physiotherapy; and 3·2 (1·82−10·0) if they underwent surgical procedures. The rate of clinical infection amongst patients with this strain of MRSA was 26% and included life-threatening infections such as septicaemia, underlining the potential virulence of MRSA. Surgery and physiotherapy may have been markers of debility. Physiotherapy was probably a marker of increased rates of contact with all hospital staff, and high standards of hand hygiene should be promoted amongst all staff as the most important factor in controlling an outbreak of MRSA. Good bed management is essential for hospital infection control.     

医院内感染病原菌及其对抗生素的耐药状况

调查1988年3月～5月我院591例住院病例,发生96例次院内感染,总发病率16.2％。院内感染病原菌中,革蓝氏阴性杆菌占72.9％,革蓝氏阳性球菌占12.9％,念珠菌属占14.1％。院内感染病原菌的耐药性明显高于院外菌株。绿脓杆菌对庆大霉素和羧苄青霉素的耐药率分别为63.6％和54.5％。其它革蓝氏阴性杆菌院内株对常用抗生素如氨苄青霉素、羧苄青霉素、庆大霉素和妥布拉霉素的耐药率分别为82.5％、 67.5％、47.5％和45％。革蓝氏阳性球菌院内株的耐药性也很严重,表葡菌对多种半合成青霉素类、红霉素、复方新诺明甚至万古霉素的耐药率达60％以上。同时分离出耐甲氧西林金葡菌。     

International spread of major clones of methicillin resistant staphylococcus aureus: nosocomial endemicity of multi locus sequence type 239 in Saudi Arabia and Romania

Phenotypically identified methicillin resistant Staphylococcus aureus (MRSA) strains from several hospitals in Romania and Saudi Arabia (n = 103 and 68, respectively) were confirmed to be MRSA by mecA PCR and PBP-2' based latex agglutination. Subsequently, strains were differentiated at the sub-species level using pulsed field gel electrophoresis (PFGE) of SmaI DNA macro-restriction fragments. Comparison of the PFGE fingerprints identified major clusters of strains, persistently present in the various hospitals. Endemicity of certain strains was identified, amongst others one due to a particularly methicillin resistant type in the burn wound sector of the Romanian hospital. No PFGE-based overlap was found between the Saudi and Romanian strains. However, multi locus sequence typing (MLST), performed for 20% of all strains, revealed that genuine genetic similarity was obscured by the PFGE analysis. In both the Romanian and Saudi hospitals the renowned sequence type (ST) 239 was very over-represented. This was especially apparent in Saudi Arabia, where all strains except two shared the ST 239 genotype. This clonal type has previously been identified in a variety of other countries. Despite the MLST concordance, PFGE data indicate that ST 239 diversifies while maintaining its core genome intact. ST 80, another previously but less frequently identified clone, was introduced in 2000 in the Romanian institutes and persisted over the past 3 years as a frequent cause of infections in a surgical department. The successful MRSA types can acquire prominent positions in hospitals of previously low-endemicity MRSA status.     

Frequency and Transferability of Trimethoprim and Sulfonamide Resistance in Methicillin-Resistant Staphylococcus aureus and Staphylococcus epidermidis

A total of 374 Staphylococcus aureus and 126 Staphylococcus epidermidis strains from 14 countries were studied for their resistance to methicillin, trimethoprim (Tp) and sulfonamides (Su), alone and combined (TpSu). The frequency of resistance to Tp, Su and TpSu was much higher in methicillin-resistant S. epidermidis (MRSE) than in methicillin-resistant S. aureus (MRSA). Considerable differences, however, existed in isolates from different countries. Resistance to Tp, Su or TpSu in MRSA was low or absent in isolates from Switzerland, Spain, Japan, Mexico, Argentina and Chile, but high in isolates from Germany and Brazil. High level Tp resistance mostly resided on large plasmids. It could be transferred in 17 out of 97 strains. Su resistance was never cotransferred. Strains cured of their large Tp resistance plasmids remained Su-resistant, which suggests a chromosomal location of Su resistance.     

A rapid,high‐throughput screening method for carriage of methicillin‐resistant Staphylococcus aureus

Rapid screening of methicillin‐resistant Staphylococcus aureus (MRSA) colonization prior to hospital admittance is important to reduce nosocomial infections and health care costs. Molecular detection of mecA and S. aureus specific target genes has become widely established for this purpose. However, there are still limitations in potential for high‐throughput screening in the methods described. We have compared the time aspects and workload of four different DNA preparation platforms, resulting in an automated and simple MRSA screening method which combines two liquid handling systems and a simple lysis buffer. We have further transferred our in‐house dual real‐time PCR to a fast‐PCR protocol, reducing the time and labour spent on these samples to a minimum.     

某综合性中医院2018~2020年耐甲氧西林金黄色葡萄球菌分布特点和医院感染监测情况分析

目的 了解某综合性中医院耐甲氧西林金黄色葡萄球菌（MRSA）的分布特点及医院感染情况,为多重耐药菌医院感染控制工作提供依据。方法 回顾性分析安徽中医药大学第一附属医院2018~2020年住院的166 115例患者检出的MRSA监测资料,将患者分为MRSA医院感染组（130例）和非MRSA医院感染组（446例）。采用单因素和多因素logistic回归分析患者MRSA医院感染的分布特点及危险因素。结果 2018~2020年住院患者共检出MRSA 576株,总检出率为34.95%,经趋势χ²检验,MRSA检出率呈逐年下降趋势（χ²=20.089,P<0.001）。MRSA菌株主要来源是痰（52.95%）和咽拭子（15.97%）;分离出的MRSA主要集中在神经外科（49.83%）、肾病科（7.64%）;分离出的MRSA菌株主要分布在冬季（27.95%）、春季（27.43%）。3年来,共有130例患者发生MRSA医院感染,MRSA总的医院感染发病率为0.78‰。2018~2020年MRSA医院感染发病率分别为0.68‰、0.74‰、0.96‰,经趋势χ²检验,MRSA医院感染发病率随年份增加的趋势无统计学意义（χ²=2.508,P=0.113）。单因素分析结果显示,MRSA医院感染组与非MRSA医院感染组在年龄、住院时间、基础疾病、侵入性操作4个方面比较,差异均有统计学意义（P<0.05）。多因素分析显示,年龄、住院时间和有侵入性操作3个因素是患者MRSA医院感染的危险因素（P<0.05）。结论 通过对医院MRSA分布及医院感染情况进行监测和分析,能够及早发现其易感高危人群和危险因素,及时准确地掌握其分布和感染变化情况,对指导临床做好多重耐药菌感染防控工作具有重要的意义。     

Prevalence of Oxacillin-Susceptible Methicillin-Resistant Staphylococcus aureus Nasal Carriage and their Clonal Diversity among Patients Attending Public Health-Care Facilities

Context: Nosocomial infections arise from many microorganisms, including Staphylococcus aureus. Aims: The aim of this study is to determine the molecular epidemiology of circulating methicillin-resistant S. aureus (MRSA) clones among patients attending community and health-care facilities in Nova Friburgo, RJ, Brazil. Methods: A total of 1002 nasal swab samples were collected from May 2010 to September 2015. S. aureus isolates were identified through phenotypic tests, submitted to antimicrobial susceptibility tests and genotypic analysis to detect mecA, panton-valentine leucocidin (PVL) genes, SCCmec, SPA and multilocus sequencing typing (MLST) typing. Results: We identified 294 (29.3%) isolates as S. aureus and 91 (9.1%) as MRSA. A total of 17 isolates did not present a correlation between phenotypic and genotypic resistance profiles. Among MRSA isolates, 17 (18.7%) carried PVL genes. A total of 20 different SPA types were determined, being grouped by MLST into eight different sequence types. ST5/t002 was the most prevalent genotype found among these isolates. Conclusions: There is a gradual colonisation shift happening in the infection pattern by S. aureus in Brazil. The Brazilian Epidemic Clone (ST239-SCCmecIIIa-PVL-) seems to be substituted by isolates from different clonal complexes, such as ST5, ST8 and ST30. The non-correlation between phenotypic/genotypic resistance profile observed in some isolates suggests the presence of other methicillin resistance mechanisms different from mecA presence or a difference in the nucleotide sequence, which prevents the primers to identify the specific region during polymerase chain reaction reactions. MRSA identification should be based on phenotypic and genotypic testing to ensure the various types of resistance mechanisms.