Intermediate vancomycin susceptibility in a community-associated MRSA clone

We describe a case of treatment failure caused by a strain of USA300 community-associated methicillin-resistant Staphylococcus aureus (MRSA) with intermediate susceptibility to vancomycin and reduced susceptibility to daptomycin. The strain was isolated from the bone of a 56-year-old man with lumbar osteomyelitis after a 6-week treatment course of vancomycin for catheter-associated septic thrombophlebitis.     

An assessment of triclosan susceptibility in methicillin-resistant and methicillin-sensitive Staphylococcus aureus

Triclosan is widely used to reduce skin colonization with staphylococci and is incorporated into methicillin-resistant Staphylococcus aureus (MRSA) eradication regimes. Using an agar dilution method, the minimum inhibitory concentration (MIC) to triclosan was determined for 186 isolates of MRSA and methicillin sensitive Staphylococcus aureus (MSSA). Fourteen isolates (7.5%) were detected with a MIC > or = 1.0 part per million (ppm). There was no significant difference between the incidence of triclosan resistance in strains of MSSA and MRSA. None of 16 strains of MRSA which exhibited low-level mupirocin resistance had MIC's > or = 1.0 ppm. Increased MIC's of staphylococci to triclosan may contribute to treatment failure when used to eradicate staphylococcal carriage. We suggest that routine susceptibility testing of staphylococci against triclosan might now be indicated.     

A Report on The First Case of Vancomycin-Intermediate Staphylococcus aureus (VISA) in Hawai‘i

The state of Hawai‘i has the highest prevalence of methicillin-resistant Staphylococcus aureus (MRSA) infection in the United States. Since vancomycin is the most frequently-prescribed antibiotic for healthcare-associated MRSA infection, there is concern for development of vancomycin resistance. We report on a 61 year-old woman with history of previous successful treatments of MRSA bacteremia with vancomycin. She was later hospitalized for catheter-related MRSA bacteremia that persisted despite vancomycin treatment. The vancomycin minimal inhibitory concentration (MIC) was initially 1–2 µg/ml, suggesting susceptibility, but changed to 4µg/ml. At this level, the organism was classified as a vancomycin-intermediate Staphylococcus aureus (VISA). Therapy was changed from vancomycin to daptomycin, and the patient''s blood cultures were sterilized. High suspicion of VISA should be raised in MRSA-infected patients who fail or have a history of vancomycin therapy so that additional susceptibility testing and appropriate antibiotic therapy can be promptly commenced to reduce the morbidity associated with VISA infection.     

Detection of qacA/B in clinical isolates of methicillin-resistant Staphylococcus aureus from a regional healthcare network in the eastern United States

We describe the clinical, microbiologic, and molecular features of the first series of qacA/B-containing strains of methicillin-resistant Staphylococcus aureus from infected US patients. All qac-carrying strains were clonally diverse, and qacA strains exhibited increased tolerance to chlorhexidine as measured by minimum inhibitory concentrations, minimum bactericidal concentrations, and postexposure colony counts.     

Staphylococcus aureus with reduced susceptibility to vancomycin--Illinois, 1999

Staphylococcus aureus is one of the most common causes of hospital- and community-acquired infections. Nosocomial methicillin-resistant S. aureus (MRSA) infections have become common, and cases of community-acquired MRSA infections also have occurred. Since 1996, vancomycin-intermediate S. aureus (VISA; vancomycin minimum inhibitory concentration [MIC = 8-16 microg/mL) has been identified in Europe, Asia, and the United States. The emergence of reduced vancomycin susceptibility in S. aureus increases the possibility that some strains will become fully resistant and that available antimicrobial agents will become ineffective for treating infections caused by such strains. This report describes the fourth case of confirmed VISA from a patient in the United States.     

Control of a methicillin-resistant Staphylococcus aureus outbreak in a neonatal intensive care unit by unselective use of nasal mupirocin ointment

In September 1996, an outbreak of methicillin-resistant Staphylococcus aureus (MRSA) colonization occurred in the neonatal intensive care unit (NICU) of our hospital. After failing to control the outbreak by conventional methods we implemented an intranasal blanket use programme of mupirocin ointment from the beginning of November 1997. In the programme, patients who had been carrying MRSA received intranasal administration of the ointment three times daily for the first three days and consecutively three times weekly, while newly admitted patients and those who had not been colonized were prophylactically medicated three times weekly. This blanket administration was executed for one month. Methicillin-resistant Staphylococcus aureus colonization became undetectable in all but one intubated inpatient who had already been colonized before the start of the programme, and no new acquisitions occurred until the middle of January 1998, seven weeks after the termination of the blanket use programme. The rate of colonized patients in the unit also decreased. During and after the programme, neither an increase in minimum inhibitory concentration for the antibiotic nor apparent adverse reactions in any of the treated patients were observed. We concluded that this procedure is an effective method of controlling an MRSA outbreak in an NICU when the outbreak cannot be managed with conventional measures.     

Epidemiology of methicillin-resistant Staphylococcus aureus at the Kenézy Hospital between 1999 and 2004

INTRODUCTION: The prevention of the spread of multiresistant microorganisms, especially methicillin-resistant Staphylococcus aureus is the main problem of epidemiology in our era. Kenézy Hospital was among the firsts to deal with the laboratory diagnosis of methicillin-resistant Staphylococcus aureus infection in Hungary, looking for the possibilities to isolate, and detect methicillin-resistant Staphylococcus aureus in patients (colonised and infected), and to provide for them proper treatment and complex management. AIMS: The authors aimed to help the work of infection control professionals by sharing their experience and through the analysis of their data. METHODS: The authors analysed the data on the incidence of infection of methicillin-resistant Staphylococcus aureus positive patients from 1999 at the Kenézy Hospital and investigated the effect of infection control policies on the incidence of infection. RESULTS: On the hospital level the lowest frequency of methicillin-resistant Staphylococcus aureus positive patients was found in 2003. The authors identified the Rehabilitation, the Traumatology and the Intensive Care Department as high risk units. The higher incidence was caused by the endemic occurrence of the disease at the specific wards. The methicillin-resistant Staphylococcus aureus infections became more severe every year, demonstrated by the increasing positivity rate of the blood cultures. Based on the identification of the most frequent phage types in each year, an epidemic strain, unlike in England, could not be found at the Kenézy Hospital. CONCLUSIONS: The number of methicillin-resistant Staphylococcus aureus positive patients at an institute depends on the institute's efforts to effectively apply microbiological screening. At a department where methicillin-resistant Staphylococcus aureus is endemic, elimination of the agent and that of the endemia are difficult tasks for the infection control team.     

Vancomycin-resistant Staphylococcus aureus--New York, 2004

Staphylococcus aureus is a common cause of hospital- and community-acquired infections. The development of vancomycin-resistant enterococci in 1988 led the way to the emergence of vancomycin-resistant S. aureus (VRSA) (minimum inhibitory concentration [MIC] > or =32 microg/mL [3]), first recognized in 2002. This report describes the third documented clinical isolate of VRSA from a patient in the United States and provides evidence of failure to detect this VRSA by commonly used automated antimicrobial susceptibility testing.     

Hybrid molecules between benzenesulfonamides and active antimicrobial benzo[d]isothiazol-3-ones

Novel hybrid molecules between benzenesulfonamides and active antimicrobial 2-amino-benzo[d]isothiazol-3-ones were synthesized and characterised and their in vitro antimicrobial activity was evaluated by the minimal inhibitory concentration (MIC). The compounds exhibit moderate antibacterial properties against gram-positive bacteria (MIC 6-100 microg ml(-1)) such as several bacilli, staphylococci and streptococci, including methicillin-resistant Staphylococcus aureus and Staphylococcus epidermidis strains, while no inhibition of gram-negative Escherichia coli is detected up to the concentration of 100 microg ml(-1). Synergistic inhibitory activity occurs when sulfanilamides 4a and 4c are tested in combination with trimethoprim against S. aureus. Concerning antifungal properties, only compound 4c is able to inhibit the growth of Saccharomyces cerevisiae and Cryptococcus neoformans yeasts and several dermatophytes. Structure-activity relationships are discussed.     

Reduction in incidence of nosocomial methicillin-resistant Staphylococcus aureus (MRSA) infection in an intensive care unit: role of treatment with mupirocin ointment and chlorhexidine baths for nasal carriers of MRSA.

After the introduction of routine treatment for every nasal carrier of methicillin-resistant Staphylococcus aureus, active follow-up surveillance for nosocomial methicillin-resistant S. aureus infection was conducted for 5 years in an intensive care unit of a tertiary-care teaching hospital. There was a significant decrease in the incidence of nosocomial methicillin-resistant S. aureus infection during the later years of follow-up. Decolonization of nasal carriers of methicillin-resistant S. aureus is probably associated with such findings.     

In vitro and in vivo study of fosfomycin in methicillin-resistant Staphylococcus aureus septicaemia

Five hundred strains of methicillin-resistant Staphylococcus aureus were tested against various anti-staphylococcal agents. Vancomycin, fusidic acid and fosfomycin were found to be the most effective. Only 1 strain out of 500 was resistant to fosfomycin. Three patients with methicillin-resistant Staphylococcus aureus septicaemia were successfully treated by fosfomycin. We conclude that fosfomycin could be the drug of choice for methicillin-resistant Staphylococcus aureus infection.     

In vitro and in vivo study of fosfomycin in methicillin-resistant Staphylococcus aureus septicaemia.

Five hundred strains of methicillin-resistant Staphylococcus aureus were tested against various anti-staphylococcal agents. Vancomycin, fusidic acid and fosfomycin were found to be the most effective. Only 1 strain out of 500 was resistant to fosfomycin. Three patients with methicillin-resistant Staphylococcus aureus septicaemia were successfully treated by fosfomycin. We conclude that fosfomycin could be the drug of choice for methicillin-resistant Staphylococcus aureus infection.     

Nasal carriage of methicillin-resistant Staphylococcus aureus by hospital staff in north Jordan.

The nasal carriage of methicillin-resistant Staphylococcus aureus was detected in 550 hospital staff members of four hospitals in north Jordan. Of the 109 (19.8%) individuals tested who were nasal carriers of S. aureus, only 32 (5.8%) were found to be carriers of methicillin-resistant Staphylococcus aureus. The carriers were four doctors, 23 nurses, three laboratory technicians, one maid and an administrator. It was noted that 25 (78.1%) of these carriers were in constant contact with patients in operating theatres, surgical wards or intensive care units. It was not clear whether the carriers were short- or long-term carriers, or whether they were persistent sources of methicillin-resistant Staphylococcus aureus. Decontamination of these carriers was considered among other control measures to avoid the dangerous outcome of hospital outbreaks caused by this potential pathogen.     

Isolation in Brazil of nosocomial Staphylococcus aureus with reduced susceptibility to vancomycin.

OBJECTIVE: To evaluate the possible presence of vancomycin-resistant Staphylococcus aureus (VRSA) in a Brazilian hospital. DESIGN: Epidemiological and laboratory investigation of nosocomial VRSA. METHODS: 140 methicillin-resistant S aureus strains isolated between November 1998 and October 1999 were screened for susceptibility to vancomycin. The screening was carried out by using brain-heart infusion agar (BHIA) supplemented with 4, 6, and 8 microg/mL of vancomycin. The minimum inhibitory concentration (MIC) determination was carried out as standardized by the National Committee for Clinical Laboratory Standards using the broth macrodilution, agar-plate dilution, and E-test methods. PATIENTS: Hospitalized patients exposed to vancomycin. RESULTS: 5 of the 140 isolates had a vancomycin MIC of 8 microg/mL by broth macrodilution, agar plate dilution, and E-test methods. Four VRSA strains were isolated from patients in a burn unit who had been treated with vancomycin for more than 30 days, and one from an orthopedic unit patient who had received vancomycin treatment for 7 days. Pulsed-field gel electrophoresis characterized four of the VRSA strains as belonging to the Brazilian endemic clone. All five strains were negative for vanA, vanB, and vanC genes by polymerase chain reaction. Transmission electron microscopy of the five strains revealed significantly thickened cell walls. One patient died due to infection caused by the VRSA strain. CONCLUSIONS: This is the first report of isolation of VRSA in Brazil and the first report of isolation of multiple VRSA strains from one facility over a relatively short period of time. This alerts us to the possibility that VRSA may be capable of nosocomial transfer if adequate hospital infection control measures are not taken.     

葡萄干提取物对两种耐药菌的ESBLs活性抑制作用评价

为寻找天然抗菌药物,在前一阶段试验结果的基础上,选用合适方法浸提葡萄干活性成分,针对耐药性强的革兰阳性金黄色葡萄球菌及革兰阴性铜绿假单胞菌的ESBLs抑制作用以及最低抑菌浓度(MIC)加以评价。实验结果显示,葡萄干提取物对金黄色葡萄球菌及铜绿假单胞菌的ESBLs活性均有明显抑制作用,从最低抑菌浓度反应出,葡萄干提取液对铜绿假单胞菌的抑杀能力强。说明葡萄干提取物中有可以抑杀病原菌的成分,也为从葡萄干中获得有效成分抑杀耐药菌开拓了思路。     

Syntheses and antibacterial activity of a series of 3-(pyridine-3-yl)-2-oxazolidinone

The syntheses of substituted piperazinyl pyridyl oxazolidinones 8-16 are described. Their in vitro activities against Gram-positive organisms such as Staphylococcus aureus, Staphylococcus epidermidis, Streptococcus and enterococcus were evaluated by minimum inhibitory concentration (MIC) determination. Compound 8 and 10 were found to be superior to linezolid.     

氯氰碘柳胺对金黄色葡萄球菌的体外抗菌活性研究

目的探讨氯氰碘柳胺对临床分离的金黄色葡萄球菌(SAU)的体外抗菌活性,为进一步探讨其在临床应用的可能性提供依据。方法临床分离的金黄色葡萄球菌102株,其中耐甲氧西林金黄色葡萄球菌(MRSA)46株,甲氧西林敏感金黄色葡萄球菌(MSSA)56株,采用微量肉汤稀释法测定氯氰碘柳胺,对金黄色葡萄球菌的体外最低抑菌浓度(MIC)值。结果氯氰碘柳胺对MRSA或MSSA的MIC值范围均为0.5～2.0 mg/ml,MIC50均为1.0 mg/ml,MIC90均为2.0 mg/ml。结论氯氰碘柳胺对MRSA或MSSA体外均有较好的抗菌活性,两者间的MIC50与MIC90差异均无统计学意义。     

Synthesis, antimicrobial activity and possible mechanism of action of 9-bromo-substituted indolizinoquinoline-5,12-dione derivatives

A series of 9-bromo-substituted indolizinoquinoline-5,12-dione derivatives was synthesized. Antimicrobial activity assessment indicates that compounds 1, 26, 27 and 28 exhibit strong activity against gram-positive bacterial strains, including Beta-hemolytic streptococcus CMCC32210, Staphylococcus aureus ATCC25923, Staphylococcus epidermidis ATCC12228, Enterococcus faecalis ATCC29212 and methicillin-resistant S. aureus ATCC43300 (MRSA). Compound 27 shows the best anti-MRSA activity with an MIC value of 0.031 μg/ml. To assess the mechanism of action, the inhibitory activities of compound 1 against DNA gyrase and DNA topoisomerase IV were also measured. The results indicate that compound 1 has strong inhibitory effects on the Escherichia coli DNA gyrase supercoiling activity and S. aureus Topo IV relaxing activity.     

两种方法处理后布尿布中微生物含量和种类的比较研究

目的:比较使用后经医院常规消毒的布尿布和家庭热水清洗处理后的布尿布中的微生物含量和种类的差别。方法:使用后的布尿布经医院常规消毒和家庭热水清洗处理后分别检测了细菌总数、霉菌/酵母菌、大肠杆菌的含量以及铜绿假单胞菌和耐甲氧西林金黄色葡萄球菌。结果:家庭热水清洗处理后的布尿布中64份尿布均检测出细菌,细菌总数的平均值为1450348 cfu/g;对32份样品中霉菌/酵母菌进行了检测,其中30份尿布中检测为阳性,其平均值为726.6 cfu/g;7份尿布中检测出大肠杆菌,平均值为721.1 cfu/g;对铜绿假单胞菌的鉴定均为阴性;46份尿布耐甲氧西林的金黄色葡萄球菌(MRSA)鉴定为阳性;经医院常规消毒后的布尿布中55份尿布中均检测出细菌,细菌总数的平均值为30.9 cfu/g;18份尿布中检测出霉菌/酵母菌,平均值为1.1 cfu/g;64份尿布中均未检出大肠杆菌;对铜绿假单胞菌的鉴定均为阴性;9份尿布耐甲氧西林金黄色葡萄球菌鉴定为阳性。采用经医院常规消毒方法的多重带菌率明显低于家庭热水清洗方法。结论:使用后经过医院常规消毒的布尿布中微生物的浓度明显低于家庭热水清洗处理后的布尿布,且霉菌/酵母菌、耐甲氧西林金黄色葡萄球菌和大肠杆菌是布尿布中的主要微生物。     

去甲万古霉素对ICU呼吸机相关性肺炎MRSA的治疗作用

目的分析ICU呼吸机相关性肺炎(VAP)的病原菌特点及去甲万古霉素对耐甲氧西林金黄色葡萄球菌(MRSA)的治疗作用。方法回顾性分析235份VAP的病历资料,采用VITEK-32系统鉴定病原菌种类,用纸片扩散法检测MRSA,对感染MRSA的患者用去甲万古霉素或万古霉素治疗,观察并比较两种药物的临床疗效和细菌学疗效。结果共分离出235株病原菌,其中革兰阴性菌177株,占75.32%,革兰阳性菌53株,占22.55%,真菌5株,占2.13%;分布最多的3种病原菌依次为铜绿假单胞菌、肺炎克雷伯菌和金黄色葡萄球菌,分别占30.21%、22.13%和21.70%;MRSA 43株,检出率为84.31%,43株MRSA患者去甲万古霉素治疗23例,万古霉素治疗20例,去甲万古霉素组死亡5例,死亡率为21.74%,总有效率为60.87%,万古霉素组死亡4例,死亡率为20.00%,总有效率为60.00%;两组死亡率和总有效率比较差异均无统计学意义;细菌学疗效显示,去甲万古霉素和万古霉素组的清除率分别为88.89%和87.50%,两组比较差异无统计学意义。结论 ICU呼吸机相关性肺炎患者MRSA感染率较高,去甲万古霉素对MRSA的疗效与万古霉素相当。