Methicillin-resistant Staphylococcus aureus in the hospitals of central Greece.

A total of 250 consecutive Staphylococcus aureus clinical isolates were collected during the period 1999-2000 from the five major hospitals of the district of Thessaly (Central Greece). Thirty seven (14.8%) of the isolates were mecA-positive (MRSA) in a PCR-based assay; all exhibited resistance to oxacillin (agar dilution MICs > or =4 mg/L) and were also resistant to multiple antibiotics. Most of the MRSA isolates had been collected in the intensive care units and the surgical wards of the participating hospitals in a sporadic fashion. The MRSA incidence found here was significantly lower than reported in previous studies from Greece. Molecular typing by PFGE showed that the MRSA isolates were distributed between three pulsotypes. Evaluation of various conventional methods for assessing methicillin resistance showed that oxacillin agar dilution and immunological detection of PBP2a with the Slidex MRSA Detection kit were the most reliable in this setting. Misclassifications of isolates exhibiting low-level resistance (oxacillin MIC 2-4 mg/L) occurred with the salt agar screen, the oxacillin disk diffusion and the ATB Staph System methods.     

Anti-methicillin resistant Staphylococcus aureus (MRSA) compounds isolated from Laurus nobilis

We found that an extract from Laurus nobilis L. (Lauraceae) leaves showed antibacterial activity against methicillin-resistant Staphylococcus aureus (MRSA). We purified two flavonoids as the effective compounds and identified them as kaempferol 3-O-alpha-L-(2',4'-di-E-p-coumaroyl)-rhamnoside (C2) and kaempferol 3-O-alpha-L-(2'-Z-p-coumaroyl-4'-E-p-coumaroyl)-rhamnoside (C3). Both compounds showed strong antibacterial activity not only against MRSA but also against vancomycin-resistant enterococci (VRE). There was low or no antibacterial activity of C2 and C3 for Streptococcus pneumoniae, Pseudomonas aeruginosa and Serratia marcescens.     

Methicillin-resistant Staphylococcus aureus: an increasing threat in New Zealand hospitals

During the three years 1985 to 1987 an increasing number of methicillin-resistant Staphylococcus aureus (MRSA) strains were identified in New Zealand each year. A total of 66 strains of MRSA were identified among isolates received from 418 patients and health personnel. The majority (337/418, 80.6%) of the isolates were from two independent large outbreaks of MRSA. All strains of MRSA were sensitive to vancomycin, rifampicin and fusidic acid. An overseas origin, usually Australia, was identified for 48.4% of strains. The majority of isolates were from patients whose host defences had been breached. Postoperative and cutaneous wounds were the commonest sites of acquisition.     

Outcomes of Daptomycin Plus Ceftaroline Versus Alternative Therapy for Persistent Methicillin-resistant Staphylococcus aureus (MRSA) Bacteraemia

ObjectivesThis study aimed to evaluate both efficacy and safety of combination therapy with daptomycin plus ceftaroline (DAP/CPT) versus alternative therapy in the treatment of persistent methicillin-resistant Staphylococcus aureus bacteraemia (MRSAB).MethodsThis retrospective, single-centre study investigated adult patients who underwent a change in antibiotic therapy for persistent MRSAB. Daptomycin plus ceftaroline was compared with alternative therapy after initial treatment with vancomycin or DAP monotherapy was modified. The primary outcome was in-hospital mortality, and several secondary efficacy and safety outcomes were evaluated.ResultsA total of 68 patients with persistent MRSAB had initial therapy switched to DAP/CPT (n = 43) or alternative therapy (n = 25). In-hospital mortality was similar with DAP/CPT versus alternative therapy (16.3% vs. 16%; P = 1.0). On average, the total duration of bacteraemia was numerically 1 day less in patients switched to DAP/CPT (11.4 days vs. 12.5 days; P = 0.5). Daptomycin plus ceftaroline was de-escalated in 81% of patients after receiving combination therapy for an average of 12.5 days. Secondary outcomes, including rates of adverse events and emergence of antimicrobial resistance, were similar between the two groups.ConclusionsSwitching to DAP/CPT after approximately 1 week of persistent MRSA bacteraemia may result in similar clinical outcomes when compared with alternative therapy. Rates of adverse events and emergence of antimicrobial resistance were low without a statistically significant difference observed between DAP/CPT and alternative therapy. These findings, as well as the impact of earlier switch or prolonged treatment with the combination, require further investigation.     

Caco-2 cells cytotoxicity of nifuroxazide derivatives with potential activity against Methicillin-resistant Staphylococcus aureus (MRSA)

It is important to determine the toxicity of compounds and co-solvents that are used in cell monolayer permeability studies to increase confidence in the results obtained from these in vitro experiments. This study was designed to evaluate the cytotoxicity of new nifuroxazide derivatives with potential activity against Methicillin-resistant Staphylococcus aureus (MRSA) in Caco-2 cells to select analogues for further in vitro permeability analyses. In this study, nitrofurantoin and nifuroxazide, in addition to 6 furanic and 6 thiophenic nifuroxazide derivatives were tested at 2, 4, 6, 8 and 10 μg/mL. In vitro cytotoxicity assays were performed according to the MTT (methyl tetrazolium) assay protocol described in ISO 10993-5. The viability of treated Caco-2 cells was greater than 83% for all tested nitrofurantoin concentrations, while those treated with nifuroxazide at 2, 4 and 6 μg/mL had viabilities greater than 70%. Treatment with the nifuroxazide analogues resulted in viability values greater than 70% at 2 and 4 μg/mL with the exception of the thiophenic methyl-substituted derivative, which resulted in cell viabilities below 70% at all tested concentrations. Caco-2 cells demonstrated reasonable viability for all nifuroxazide derivatives, except the thiophenic methyl-substituted compound. The former were selected for further permeability studies using Caco-2 cells.     

Community-associated methicillin-resistant Staphylococcus aureus (MRSA) in Australia

A series of epidemics of community-associated methicillin-resistant Staphylococcus aureus (CA-MRSA) have occurred in Australia, starting in Western Australia in the early 1990s, in the Northern Territory soon thereafter and in eastern states in the mid 1990s. The Western Australian epidemic has been due mainly to Panton–Valentine leukocidin (PVL)-negative clones, whilst PVL-positive clones have predominated in the east. More recently, the major epidemic clones have spread throughout the country, whilst multiple new minor clones have emerged, mainly in Western Australia. A total of 45 clones of CA-MRSA have been detected in Australia to date: 30 of these carry SCCmec IV, 6 carry SCCmec V and 9 carry novel SCCmec types. Overall, CA-MRSA clones have been associated predominantly with skin and soft-tissue infections. PVL-positive clones have been associated with furunculosis, necrotising pneumonia and osteomyelitis and have caused fatalities in otherwise healthy children and young adults. Initial treatment of these infections remains problematic, as it is frequently inappropriate. Of particular concern, healthcare-associated acquisition of CA-MRSA clones is now increasing, although major hospital outbreaks have not occurred yet.     

Reduced glycopeptide susceptibility in methicillin-resistant Staphylococcus aureus (MRSA)

Vancomycin and other glycopeptide antibiotics are the current mainstay of therapy for infections caused by methicillin-resistant Staphylococcus aureus (MRSA). However, the high prevalence of MRSA has led to increased use of vancomycin in chronic and seriously ill patients and has resulted in the emergence of MRSA with reduced susceptibility to glycopeptides. Multiple MRSA phenotypes demonstrate reduced susceptibility to glycopeptides. According to the Clinical and Laboratory Standards Institute, vancomycin-intermediate S. aureus (VISA) are now those isolates with minimum inhibitory concentrations (MICs) between 4 microg/mL and 8 microg/mL, whilst heterogeneous VISA (hVISA) strains appear to be susceptible to vancomycin but contain a subpopulation of cells with reduced susceptibility to vancomycin (MICs > or = 4 microg/mL). At this time, MICs for these strains are reported to range between 1 microg/mL and 2 microg/mL. Vancomycin-resistant S. aureus (VRSA) are defined as those having MICs > or = 16 microg/mL. The detection of reduced susceptibility to vancomycin by routine susceptibility testing is unreliable and vancomycin non-susceptibility is most probably being underreported. Reports of reduced clinical efficacy associated with vancomycin MICs between 1 microg/mL and 2 microg/mL have been published. Patients most at risk of infection by hVISA, VISA and VRSA appear to be those with previous exposure to vancomycin. VRSA appears in the elderly and those with chronic leg or decubitus ulcers mainly containing vancomycin-resistant enterococci, which were probably the donor organism of the vanA gene to S. aureus. All MRSA strains recovered from patients whose infections do not respond to vancomycin treatment should be tested accurately for vancomycin susceptibility if these phenotypes are not to be missed. Treatment options for infections due to MRSA with reduced susceptibility to vancomycin are limited. Rapid identification of patients harbouring VRSA, VISA or hVISA as well as prompt isolation and adherence to infection control protocols are paramount in controlling the dissemination of these pathogens.     

Meticillin-resistant Staphylococcus aureus (MRSA): screening and decolonisation

Meticillin-resistant Staphylococcus aureus (MRSA) infections are of increasing importance to clinicians, public health agencies and governments. Prevention and control strategies must address sources in healthcare settings, the community and livestock. This document presents the conclusions of a European Consensus Conference on the role of screening and decolonisation in the control of MRSA infection. The conference was held in Rome on 5-6 March 2010 and was organised jointly by the European Society of Clinical Microbiology and Infectious Diseases (ESCMID) and the International Society of Chemotherapy (ISC). In an environment where MRSA is endemic, universal or targeted screening of patients to detect colonisation was considered to be an essential pillar of any MRSA control programme, along with the option of decolonising carriers dependent on relative risk of infection, either to self or others, in a specific setting. Staff screening may be useful but is problematic as it needs to distinguish between transient carriage and longer-term colonisation. The consequences of identification of MRSA-positive staff may have important effects on morale and the ability to maintain staffing levels. The role of environmental contamination in MRSA infection is unclear, but screening may be helpful as an audit of hygiene procedures. In all situations, screening procedures and decolonisation carry a significant cost burden, the clinical value of which requires careful evaluation. European initiatives designed to provide further information on the cost/benefit value of particular strategies in the control of infection, including those involving MRSA, are in progress.     

Activity of ACHN-490 against meticillin-resistant Staphylococcus aureus (MRSA) isolates from patients in US hospitals

The activity of ACHN-490 was evaluated against 493 meticillin-resistant Staphylococcus aureus (MRSA) isolates collected in 2009-2010 from 23 US hospitals. The MIC₅₀ and MIC₉₀ values (minimal inhibitory concentrations for 50% and 90% of the organisms, respectively) for ACHN-490 were 1 and 2 μg/mL compared with 8 and 32 μg/mL for amikacin, 0.5 and 1 μg/mL for gentamicin and 2 and >16 μg/mL for tobramycin. The gene encoding the aminoglycoside-modifying enzyme APH(2″)-Ia/AAC(6′)-Ie was present in 12% of the subset of 84 isolates examined by polymerase chain reaction (PCR), whilst the gene encoding ANT(4′)-Ia was present in 89% of isolates. ACHN-490 activity was not affected by either enzyme.     

Susceptibility pattern of Staphylococcus aureus isolated in Malaysian hospitals

Isolates of 390 Staphylococcus aureus were tested against 13 different antibiotics by a disc diffusion method as recommended by the National Committee for Clinical Laboratory Standards (NCCLS). Strains were isolated from blood (5.7%), cerebrospinal fluid (0.5%), respiratory tract (11.8%), pus and wound (73.3%), urine (1.8%), genital specimens (1.0%) and other specimens (4.3%). Only 4.6% of the isolates were fully susceptible to all the drugs tested. Resistance to penicillin was 94.1%, methicillin, 39.7%, chloramphenicol, 8.5%, ciprofloxacin, 29.2%, clindamycin, 2.1%, erythromycin, 45.9% gentamicin, 40.5%; rifampicin, 3.3% tetracycline, 47.2%, co-trimoxazole, 38.5%, mupirocin, 2.8%, fusidic acid, 3.6%. None of the isolates was resistant to vancomycin. The susceptibility of methicillin-resistant strains to erythromycin, gentamicin, tetracycline and ciprofloxacin was low, while clindamycin, fusidic acid, mupirocin, and rifampicin remained active.     

双黄连联合万古霉素对耐甲氧西林金黄色葡萄球菌生物被膜抑制作用的研究

目的研究双黄连联合万古霉素对MRSA生物被膜的影响。方法平板培养法培养MRSA生物被膜,银染法鉴定。96孔平板培养,分为四组:空白对照组(A组)、双黄连组(B组)、万古霉素组(C组)、双黄连+万古霉素组(D组)。经上述不同药物对生物被膜处理后,比色法测定藻酸盐含量,MTT法测定各组活菌计数。结果 1 B、C、D组作用后藻酸盐含量明显低于A组(P<0.05),D组分别较B组及C组低(P<0.05);2 B、C、D组作用后活菌计数明显低于A组(P<0.05),D组活菌计数亦分别较B组及C组低(P<0.05)。结论双黄连可抑制MRSA生物被膜合成,并有显著抑菌作用,与万古霉素有协同作用。     

Epileptogenic activity of methicillin-resistant Staphylococcus aureus (MRSA) antibiotics in rats

The present study was undertaken to clarify the epileptogenic activity induced by intracerebroventricular injection (i.c.v.) of antibiotics effective in methicillin-resistant Staphylococcus aureus (MRSA) in chronically electrode implanted rats. Teicoplanin (10-100 microg, i.c.v.) caused dose-related electroencephalographic (EEG) seizure characterized by an uninterrupted high voltage and wave complex. At the same time, the rats showed forelimb clonus, head nodding, jumping and severe convulsion. At a high dose (100 microg, i.c.v.), the drug caused a severe twisting immediately after the intracerebroventricular injection (i.c.v.) followed by jumping and violent convulsion with a continuous rhythmic spike and wave complex in EEG. On the other hand, vancomycin (30-1000 microg, i.c.v.) caused no or almost no epileptogenic activity in terms of behavior and in EEG. However, at a high dose (1000 microg, i.c.v.), the drug caused an occasional spike from the hippocampus without showing any behavioral changes in the rats. Fosfomycin (30-1000 microg, i.c.v.), cefazolin (10-100 microg, i.c.v.) and penicillin G (30-300 microg, i.c.v.), used as reference drugs, caused dose-dependent epileptogenic activity in both EEG. From these findings, it was found that teicoplanin caused a potent epileptogenic activity, different to vancomycin. Therefore, it can be concluded that vancomycin may be safety on epileptogenic activity used for the clinical purpose of infections caused by MRSA.     

Costs of hospital-acquired methicillin-resistant Staphylococcus aureus (MRSA) and its control

For most countries badly affected by methicillin-resistant Staphylococcus aureus (MRSA) there have been many years of debate about its relative virulence compared with methicillin-susceptible S. aureus (MSSA) and whether it could be controlled. Now that it is endemic in the majority of hospitals around the world, it is clear that it is at least as virulent as MSSA and is an additional burden of healthcare-acquired infection. There is increasing evidence that, despite this endemicity, control efforts can be successful, although they are often perceived as expensive. In reality, there is a large body of consistent evidence that control is highly cost effective, particularly in the context of the huge societal costs of MRSA and the future ever-greater threats that it poses.     

Infective endocarditis caused by USA300 methicillin-resistant Staphylococcus aureus (MRSA)

We report seven cases of infective endocarditis caused by USA300 methicillin-resistant Staphylococcus aureus (MRSA) at an urban, tertiary care, academic institution. Five strains were community associated and two were healthcare associated. All patients were injection drug users. Staphylococcus aureus isolates were characterised as USA300-type MRSA using pulsed-field gel electrophoresis. Five cases were right-sided endocarditis and two cases were left-sided. The mean length of in-hospital antimicrobial therapy was 23 days and the mean length of total antibiotic therapy was 55 days. Complications included heart failure resulting in valve replacement in one patient as well as death in that patient. As USA300 strains of MRSA continue to increase in prevalence, clinicians must be aware of the increasing spectrum of illness in considering management and prevention strategies.     

Update on screening and clinical diagnosis of meticillin-resistant Staphylococcus aureus (MRSA)

Based on the failure of conventional control strategies, some experts and public health officials have promoted active screening to detect asymptomatic carriers of meticillin-resistant Staphylococcus aureus (MRSA) as an effective prevention strategy. Data regarding the (cost-) effectiveness of MRSA screening have recently grown and have produced mixed results. Several clinical studies have not only provided conflicting findings but have also raised numerous issues about the appropriate populations for universal versus targeted screening, screening method(s) and intervention(s). It must also be emphasised that screening alone is not effective. Results should be followed by appropriate interventions to reduce the risk of MRSA transmission and infection. We believe a reasonable approach in most European hospitals with an MRSA on-admission prevalence of <5% is to use targeted rather than universal screening (predominantly with chromogenic media, except for high-risk units and critically ill patients for whom molecular tests could be cost effective), after carefully considering the local MRSA epidemiology, infection control practices and vulnerability of the patient population. This strategy is likely to be cost effective if linked to prompt institution of control measures.     

Relationship between arbekacin-susceptibility and aminoglycoside-resistant gene of methicillin-resistant Staphylococcus aureus (MRSA)

The susceptibility to arbekacin (ABK) of methicillin-resistant Staphylococcus aureus (MRSA) was investigated to find out how it related to aac(6')/aph(2") gene. In 49 isolates of MRSA for which MIC of ABK ranged from 0.125 to 64 micrograms/ml, the MICs of ABK for 38 strains carrying aac(6')/aph(2") gene were widely distributed from 0.25 to 64, whereas those for 11 strains without that gene were all < or = 0.5 microgram/ml. Residual rate of ABK activity was higher than that of gentamicin after the reaction with each crude enzyme preparation extracted from 3 isolates of MRSA, carrying aac(6')/aph(2") and aad(4',4") genes. Furthermore, 97 strains of MRSA isolated at Kanagawa prefecture in Japan in 1999 were all sensitive to ABK, although 28 strains of them carried aac(6')/aph(2") gene. These results showed that ABK resistance was not necessarily related to carrying aac(6')/aph(2") gene in clinical isolates of MRSA.     

耐甲氧西林金黄色葡萄球菌肺炎小鼠感染模型的建立与评估

目的 本研究采用临床分离鉴定的ST239型耐甲氧西林金黄葡萄球菌(MRSA)感染BALB/c小鼠,建立小鼠肺炎模型,对小鼠的临床症状、肺载菌量与组织病理学变化进行时相性监测,并用该模型验证万古霉素对小鼠的治疗效果.方法 取35只小鼠随机分成MRSA感染组、药物组和对照组,通过滴鼻方式分别滴入50μL细菌(前两组)与PBS(对照组);感染一天后对药物组用同样的方式滴入万古霉素,CT检测肺部的变化,并对肺载菌量和组织病理学变化进行观察.结果 与对照组比较,CT和细菌计数等结果表明MRSA感染组和药物组的肺组织有明显的炎症反应,载菌量较高;与感染组相比,药物组小鼠肺部的载菌量明显降低,气管和肺部的组织病理学症状明显减轻.结论 本实验结果表明小鼠MRSA肺炎模型成功建立,并可用于药物疗效的比较评估.该模型的建立,将为进一步研究临床分离的MRSA的病原特性、发病机理、治疗方法等,提供可靠的小动物模型.     

A therapy for methicillin-resistant Staphylococcus aureus (MRSA) infections in obstetrics and gynecology

Although it has been reported that the incidence of methicillin-resistant Staphylococcus aureus (MRSA) infections is extremely low in the obstetrics/gynecology setting, we recently had 5 patients with MRSA infections in the obstetrics/gynecology departments of 4 clinics in Yamagata Prefecture from September 1990 to February 1991. 1) Classified by disease, 4 of the patients had intrauterine infections (3 puerperal intrauterine infections and 1 intrauterine infection) and 1 had a postoperative wound infection. 2) Classified by treatment after the MRSA isolates had been determined, 2 of the patients were given imipenem/cilastatin alone (which turned out to be effective), 2 were given concomitant IPM/CS + quinolone agents (ofloxacin, tosufloxacin; effective) and 1 was given minocycline and OFLX. The principal lessons we learned from these cases are that attention should be paid to the occurrence of MRSA infection even in the obstetrics/gynecology field and that the method of selecting and administering antibiotics to prevent and treat such infections should be reconsidered.