In vitro activity of daptomycin against multidrug-resistant Staphylococcus aureus and S. aureus with known virulence factors, including community-acquired methicillin-resistant isolates

The in vitro activity of daptomycin was evaluated against 360 multidrug-resistant Staphylococcus aureus isolates (including hospital-acquired isolates) and multidrug-susceptible community-acquired methicillin-resistant S. aureus with known virulence genes. All isolates were inhibited at 相似文献   

A rapid screening method for Panton-Valentine leucocidin-positive community-acquired methicillin-resistant Staphylococcus aureus belonging to multilocus sequence type 30 and its related clone using a combination of multiplex PCR and pulsed-field gel electrophoresis

Community-acquired methicillin-resistant Staphylococcus aureus (CA-MRSA), which is often positive for Panton-Valentine leucocidin (PVL), is increasingly noted as an emerging pathogen worldwide. In Japan, PVLpositive CA-MRSA belonging to multilocus sequence type (ST) 30 has spread and caused, for example, pediatric death due to community-acquired pneumonia and severe pelvic abscesses in an athlete. In this study, we investigated a new rapid screening method for PVL-positive ST30 CA-MRSA and its related clone by a combination of multiplex polymerase chain reaction (M-PCR) and pulsed-field gel electrophoresis (PFGE). For M-PCR, the targets of the assay were the five genes for PVL, collagen adhesin, bone sialoprotein adhesin, methicillin resistance, and S. aureus-specifi c thermostable nuclease. Only PVL-positive ST30 CA-MRSA strains produced all five bands in M-PCR. With PFGE, Japanese strains and most foreign strains of PVLpositive ST30 CA-MRSA shared the same pattern. Moreover, PFGE distinguished current PVL-positive CA-MRSA ST30/spa19 strains from previous PVL-positive MRSA ST30/spa43 strains (which were isolated at the time of nosocomial MRSA outbreaks in the late 1980s and early 1990s) in Japan. Thus, the M-PCR assay rapidly, and the M-PCR/PFGE combination assay more precisely, discriminated between PVL-positive ST30 CA-MRSA (or its related clone) and PVL-positive CA-MRSA belonging to other ST types such as ST1, 8, 59, and 80, PVL-negative CA-MRSA, hospital-acquired MRSA, methicillin-susceptible S. aureus, or coagulase-negative staphylococci (CNS), including MRCNS. This screening method is more useful than genotyping for routine work in many clinical laboratories.     

Genotypes, intrafamilial transmission, and virulence potential of nasal methicillin-resistant Staphylococcus aureus from children in the community

Pediatric outpatients and healthy children in the community were examined for nasal methicillin-resistant Staphylococcus aureus (MRSA) in Japan. MRSA isolation frequencies were 0.7% (3/426) and 3.7% (5/136), respectively, in pediatric outpatients and healthy children in the community (overall frequency, 1.4%). The frequency of MRSA isolation was higher in children 5–9 years of age compared with the other age groups. All eight MRSA strains isolated were Panton-Valentine leukocidin-negative. Of these, three with the genotype multilocus sequence type (ST) 8/spa606/SCCmecIV (2 cases) and ST88/spa999/SCCmecIV/exfoliative toxin A gene (eta) were identical or similar to MRSA from bullous impetigo, determined by pulsed-field gel electrophoresis. One strain with ST764 (ST5 variant)/spa2/SCCmecII/staphylococcal enterotoxin B gene seb2 (seb variant) was similar to MRSA from bacteremia, and one with ST5/spa2/SCCmecII was the Pandemic New York/Japan clone. The remaining three strains, with ST22/spa998/SCCmecI, ST380/spa799/SCCmecIV, and ST857/spa416/SCCmecII, have not been identified. All MRSA strains were resistant to one or more non-β-lactam antibiotics, and the ST5 and ST764 strains were multidrugresistant. Family analysis demonstrated parent-to-child transmission (for ST8 and ST764), as well as acquisition from outside the family (for ST8 and ST380). The data suggest that young school-age children have a higher carriage rate of nasal MRSA than children of other ages, and that not only community-acquired MRSA strains but also MRSA strains with characteristics of hospital-acquired MRSA are spreading in the community.     

Lemierre's syndrome: methicillin-resistant Staphylococcus aureus (MRSA) finds a new home

Lemierre's syndrome is septic thrombophlebitis of the internal jugular vein, arising as a complication of an oropharyngeal infection. This thrombophlebitis frequently results in septic emboli to organs such as the lungs. The causative agent in most previously described cases is Fusobacterium necrophorum, an anaerobic Gram-negative organism. We present the case of an 8-year-old previously healthy girl who came to the Emergency Department with a 5-day history of left-sided neck pain and was subsequently diagnosed with methicillin-resistant Staphylococcus aureus (MRSA) Lemierre's syndrome. MRSA has not previously been described in Lemierre's syndrome in the Emergency Medicine literature. The clinical presentation, findings, and management of the syndrome are discussed. Regardless of etiology, once the diagnosis of Lemierre's syndrome is made, long-term broad-spectrum intravenous therapy will be necessary.     

Emergence of the community-acquired methicillin-resistant Staphylococcus aureus USA300 clone in Japan

We isolated methicillin-resistant Staphylococcus aureus (MRSA) from a 3-month-old Indian girl who was born in the United States, moved to Japan, and suffered from subcutaneous abscesses in 2007. The MRSA (strain NN36) belonged to multilocus sequence type (ST) 8, exhibited agr1, staphylococcal cassette chromosome mec (SCCmec) type IVa, and coagulase type III, and was positive for Panton-Valentine leukocidin (PVL) and the arginine catabolic mobile element (ACME), just like the USA300 clone, which is the predominant community-acquired MRSA (CA-MRSA) in the United States. Strain NN36 shared an identical pulsed-field gel electrophoresis (PFGE) pattern with the USA300 clone. Although the USA300 clone is of spa1, strain NN36 possessed spa985. Strain NN36 was resistant to erythromycin and kanamycin, in addition to β-lactam agents (e.g., oxacillin). The data suggest that the USA300 clone has emerged in Japan. Because the USA300 clone has recently spread to European countries, surveillance of the USA300 clone should be actively performed in Japan.     

Multifocal pelvic abscesses and osteomyelitis from community-acquired methicillin-resistant Staphylococcus aureus in a 17-year-old basketball player

A 17-year-old female basketball player suffered from cutaneous abscesses, which complicated into a systemic progression to osteomyelitis and simultaneous iliopsoas and piriformis abscesses, adjacent to the sacroiliac joint. The causative agent was community-acquired methicillin-resistant Staphylococcus aureus with multilocus sequence type 30, spa19, and SCCmecIVc. The clinical importance of this genotype is discussed.     

Community-associated methicillin-resistant Staphylococcus aureus, eastern Argentina

Sixty-nine community-associated methicillin-resistant Staphylococcus aureus recovered in 6 healthcare centers from northeastern and eastern Argentina were genotyped by pulsed-field gel electrophoresis. The predominant pulsotype was widely distributed harbored SCCmec type IV and Panton-Valentine leukocidin genes. Representative isolates were characterized by multilocus sequence typing and spa typing, demonstrating that this clone belonged to ST5 and spa type 311.     

Application of loop-mediated isothermal amplification technique to rapid and direct detection of methicillin-resistant Staphylococcus aureus (MRSA) in blood cultures

Staphylococcus aureus is the most important pathogen in nosocomial infections, including bloodstream infections. Prompt identification of S. aureus from blood cultures and detection of methicillin resistance are essential in cases of suspected sepsis. A novel nucleic acid amplification technique, loop-mediated isothermal amplification (LAMP), which amplifies DNA under isothermal conditions (63°C) with high specificity, efficiency, and rapidity, was applied to detect methicillin-resistant S. aureus (MRSA) directly from positive blood culture bottles. MRSA-LAMP, which targets the spa gene, encoding S. aureus-specific protein A, and the mecA gene, encoding penicillin-binding protein-2′ for methicillin resistance, could detect MRSA within 2 h after the blood culture signal became positive. The diagnostic values of LAMP, compared to a duplex real-time polymerase chain reaction (Drt-PCR) assay, were 92.3% and 96.2% sensitivity, 100% and 100% specificity, 100% and 100% positive predictive value (PPV), and 96.9% and 98.4% negative predictive value (NPV), respectively. These two methods had almost the same results, but the LAMP method is more cost-effective and provides excellent availability for rapid examination in a hospital clinical laboratory. Therefore, the LAMP assay appears to be a sensitive and reliable new method to diagnose MRSA bloodstream infection for appropriate antibiotic therapy.     

Clinical features and molecular characteristics of invasive community-acquired methicillin-resistant Staphylococcus aureus infections in Taiwanese children

Highly virulent community-acquired methicillin-resistant Staphylococcus aureus (CA-MRSA) has been associated with morbidity and mortality in various countries of the world. We characterized the clinical and molecular features of pediatric invasive CA-MRSA infections in Taiwan. Between July 2000 and June 2005, 31 previously healthy children with invasive CA-MRSA infections were identified from 423 children with community-onset methicillin-resistant S. aureus infections. The medical records were reviewed. The clinical isolates, if available, were collected for molecular characterization. Sixteen (51.6%) patients were male, and the mean age was 5.7 years. Adolescents accounted for 9 (29%) cases. Eighteen children had bone and/or joint infections, 14 had deep-seated soft tissue infections, 11 had pneumonia, and 2 had central nervous system infections. Multiorgan involvement was identified in 8 of 20 bacteremic cases. Twenty-two patients (71%) required surgical interventions. The mean hospital stay was 27.4 days. All of the 15 available isolates were classified as sequence type (ST) 59 or its single locus variant and belonged to 2 previously reported community-associated clones containing staphylococcal cassette chromosome mec (SCCmec) type IV or type V(T) in Taiwan. Most of the isolates were multiresistant to clindamycin (94%) and erythromycin (97%). Eleven (73.3%) isolates carried pvl genes, and the strains harboring pvl genes were significantly associated with lung involvement. In conclusion, invasive CA-MRSA infections in pediatric population were not limited to young children. Surgical interventions were often required, and a prolonged course of antibiotic therapy was needed. A multiresistant CA-MRSA clone characterized as ST59 was identified from these children in Taiwan.     

Characterization of oxacillin-susceptible <Emphasis Type="Italic">mecA</Emphasis>-positive <Emphasis Type="Italic">Staphylococcus aureus</Emphasis>: a new type of MRSA

Methicillin-resistant Staphylococcus aureus (MRSA) has been defined as S. aureus having the mecA gene or showing a minimum inhibitory concentration (MIC) of oxacillin higher than 4 mg/l. However, some clinical isolates are mecA-positive and oxacillin-susceptible. Therefore, we surveyed the occurrence of S. aureus having the mecA gene and an MIC of oxacillin of less than 2 mg/l (oxacillin-susceptible MRSA; OS-MRSA) in a total of 480 strains of S. aureus collected from 11 hospitals in different location in Japan isolated from 2003 through 2005. We found 6 strains matching the criteria for OS-MRSA. All 6 strains were staphylococcal cassette chromosome (SCC) mec-positive, without exception, and 4 strains showed the SCCmec type III-variant, which is unique in Japan. These OS-MRSAs were least resistant to oxacillin among the MRSAs tested and they were within the susceptible range to seven other beta-lactam antibiotics tested. Thus, OS-MRSA may become a high-resistant MRSA upon the treatment of patients with beta-lactam antibiotics. To characterize whether these OS-MRSAs were hospital-acquired or community-acquired MRSAs, we tested for the presence of the genes encoding toxins. Genes encoding hemolysin, exfoliative toxin, enterotoxin, toxic shock syndrome toxin-1, and Panton-Valentine leukocidin were found in 6, 4, 0, 0, and 0 strains, respectively. These results revealed that OS-MRSAs could be classified as a new type of MRSA that exhibits properties distinguishable from either hospital- or community-acquired MRSA. Coagulase typing of the OS-MRSAs supported the above conclusion. In this study, the occurrence of OS-MRSA at a certain frequency was noted; precautions are called for in the classification of oxacillin-resistant S. aureus and in the treatment of OS-MRSA infection.     

Community-acquired methicillin-resistant Staphylococcus aureus in Madrid, Spain: transcontinental importation and polyclonal emergence of Panton-Valentine leukocidin-positive isolates

Community-acquired methicillin-resistant Staphylococcus aureus (CA-MRSA) isolates producing the Panton-Valentine leukocidin (PVL) have been reported worldwide. We describe the molecular characteristics of PVL-positive CA-MRSA strains isolated in Madrid, Spain, and analyze the clinical features of patients infected with these isolates. From 2004 to 2007, we collected 13 PVL-positive MRSA isolates from patients attending to the emergency department. The isolates were genotyped by pulsed-field gel electrophoresis, SCCmec typing, agr polymorphism, and multilocus sequence typing. Susceptibility to 29 antimicrobials was determined by the broth microdilution and by the E-test methods. The isolates belonged to 3 genotypes: ST8-SCCmec IVc (n = 11), ST5-SCCmec IVa (n = 1), and ST80-SCCmec IVc (n = 1). The corresponding agr types were I, II, and III, respectively. Five isolates were resistant to tetracycline and doxycycline, and 1 was resistant to fusidic acid (ST80). The isolates were from children (n = 9) and adults (n = 4), and were associated with skin and soft tissue infections (n = 9), otitis (n = 1), and bacteremia (n = 1). Nine patients were from South America. Our results indicate the transcontinental importation and recent emergence in Spain of PVL-positive CA-MRSA strains belonging to 3 distinct lineages, including 1 predominant (ST8-SCCmec IVc).     

Life-threatening hemoptysis in adults with community-acquired pneumonia due to Panton-Valentine leukocidin-secreting Staphylococcus aureus

Three new consecutive cases of life-threatening hemoptysis in adults with community-acquired pneumonia due to Panton-Valentine leukocidin-secreting Staphylococcus aureus are presented, focusing on the particular clinical presentation of this new entity. Between December 1999 and March 2001, three adults aged from 23 to 67 years were admitted to our respiratory intensive care unit for massive hemoptysis and septic shock associated with community-acquired Staphylococcus aureus pneumonia. Isolates were sent to the Centre National de Référence des Toxémies Staphylococciques in Lyon, France, where they were found to secrete Panton-Valentive leukocidin. The clinical course was similar in the three patients, with massive hemoptysis and septic shock necessitating mechanical ventilation. Two patients died rapidly; necropsy showed pulmonary vascular necrosis in one of them. The third patient recovered after appropriate antibiotic therapy. Leukocidin/neutrophil interactions in the pulmonary vasculature may cause severe hemoptysis in patients with community-acquired Staphylococcus aureus pneumonia secreting Panton-Valentine leukocidin. Adult patients with massive hemoptysis and suspected community-acquired pneumonia should receive antibiotic regimens covering Staphylococcus aureus.     

In vitro activity of telavancin and comparator antimicrobial agents against a panel of genetically defined staphylococci

The in vitro activity of telavancin was determined for 94 diverse Staphylococcus spp. Telavancin had MIC(90) values of 0.5 μg/mL for methicillin-susceptible, methicillin-resistant, and vancomycin-susceptible Staphylococcus aureus, and coagulase-negative staphylococci isolates. Telavancin MICs were 0.5-1 μg/mL for vancomycin-intermediate S. aureus isolates and 2-4 μg/mL for vancomycin-resistant S. aureus strains.     

In vitro activity of lysostaphin, mupirocin, and tea tree oil against clinical methicillin-resistant Staphylococcus aureus

Colonization of methicillin-resistant Staphylococcus aureus (MRSA) commonly leads to infection by the same strain. We examined the activity of lysostaphin, mupirocin, and tea tree oil against clinical MRSA (n = 98) isolates. MIC(50) (range) were as follows: lysostaphin, 0.125 mg/L (0.125-0.25); mupirocin, 0.5 mg/L (0.19-1024); tea tree oil, 1024 mg/L (512-2048). High- and low-level mupirocin resistance was noted in 9.2% of our MRSA isolates. Time kill results indicate MRSA activity at 24 h was lysostaphin = gentamicin = vancomycin (P mupirocin > tea tree oil (P >or= .05). Checkerboard testing indicated a synergistic relationship between lysostaphin and mupirocin in combination with gentamicin. Antagonism was observed with the combination of vancomycin and tea tree oil; time kill studies confirmed this result. Decolonization options are limited and resistance to mupirocin exists. Lysostaphin and tea tree oil may offer additional therapeutic options for the decolonization of MRSA where current treatment alternatives are limited.     

Antimicrobial susceptibility and molecular characteristics of 857 methicillin-resistant Staphylococcus aureus isolates from 16 medical centers in Japan (2008-2009): nationwide survey of community-acquired and nosocomial MRSA

This study is a nationwide survey of all clinical methicillin-resistant Staphylococcus aureus (MRSA) isolates, including community-acquired MRSA (CA-MRSA), in Japan. A total of 857 MRSA clinical isolates were collected from the 16 institutions throughout Japan that participated in the survey (2008-2009). The drug susceptibility and staphylococcal cassette chromosome mec (SCCmec) typing and the presence of specific pathogenic genes were evaluated. The isolates comprised SCCmec type II (73.6%), type IV (20%), and type I (6%). The percentage of SCCmec type IV isolates was significantly higher in outpatients than in inpatients. Most of the isolated strains were sensitive to vancomycin (VCM, MIC ≤2 μg/mL), linezolid (MIC ≤4 μg/mL), and teicoplanin (MIC ≤8 μg/mL). Although most strains were sensitive to VCM, the MIC value of VCM for SCCmec type II strains was higher than that for SCCmec type IV strains. Only 4 (2.3%) of 171 SCCmec type IV strains were Panton-Valentine leukocidin (lukS/F-PV)-positive. Thus, this result indicates a unique feature of SCCmec type IV strains in Japan. The information in this study not only is important in terms of local public health but will also contribute to an understanding of epidemic clones of CA-MRSA.     

Trends of β-lactam antibiotic susceptibility in blood-borne methicillin-resistant Staphylococcus aureus (MRSA) and their linkage to the staphylococcal cassette chromosome mec (SCC mec ) type

We investigated trends of beta-lactam antibiotic susceptibility in a total of 218 strains of blood-borne methicillin-resistant Staphylococcus aureus (MRSA) isolated from 1978 through 2002 at a middle-size geriatric hospital in Tokyo; the strains were classified by the MRSA marker, staphylococcal cassette chromosome mec (SCCmec). The minimum growth inhibitory concentration (MIC) of cloxacillin at which 50% of the strains were inhibited (MIC50) was 2 microg/ml in the strains isolated in 1978-1984 and 32 to 64 microg/ml in the strains isolated subsequently. Similarly, the MIC50 values of cefazolin and imipenem in the 1978-1984 isolates were 16 and 相似文献   

Nosocomial infection of β-lactam antibiotic-induced vancomycin-resistant Staphylococcus aureus (BIVR)

We report here an outbreak of β-lactam-induced vancomycin-resistant methicillin-resistant Staphylococcus aureus (MRSA; BIVR) at one of the Cancer-Institute-affiliated hospitals in Tokyo. We examined a total of 500 strains (100 per year) of clinically isolated MRSA from 1998 to 2002. The detection rates of BIVR in the years 1998, 1999, 2000, 2001, and 2002 were 10%, 9%, 49%, 15%, and 19%, respectively. To investigate the cause of the high incidence of BIVR detection in the year 2000, we carried out pulsed-field gel electrophoresis (PFGE) of the SmaI-digested chromosomal DNA of BIVR and MRSA. The results showed that 96% of the BIVR strains isolated in 2000 were classified as an identical DNA type “A”, while only 47% of the MRSA strains were classified as this type. We concluded, based on these results, that this hospital had a nosocomial infection of BIVR in the year 2000. An important message given by this study would be that nosocomial BIVR infection could occur in any hospital where MRSA infection is treated with vancomycin and β-lactam antibiotics.     

Detection of mecA-mediated resistance using reference and commercial testing methods in a collection of Staphylococcus aureus expressing borderline oxacillin MICs

Phenotypic methods for detecting mecA-mediated resistance in Staphylococcus aureus include both oxacillin and cefoxitin susceptibility tests; many laboratories perform multiple tests. Conflicting oxacillin and cefoxitin susceptibility results are most likely to occur for isolates that either have reduced susceptibility to oxacillin by a non-mecA-mediated mechanism or are mecA positive but are very heteroresistant. To understand the performance of oxacillin and cefoxitin tests for such isolates, we tested 135 S. aureus isolates using either cefoxitin or oxacillin and compared the results with mecA polymerase chain reaction. These strains either expressed borderline oxacillin MICs (1-4 microg/mL) and had undetermined mecA status or were mecA positive but were not detected by oxacillin broth microdilution (BMD) or disk diffusion (DD) in original testing. For 24-h readings, performance of cefoxitin tests (sensitivity/specificity) were DD (99/100), Etest using < or =6 microg/mL as susceptible (99/98), and Phoenix MIC using < or =4 microg/mL as susceptible (98/100). Using 6 microg/mL of cefoxitin as a screen test in both BMD and agar dilution also worked well (98/98-100). Sensitivity/specificity of oxacillin methods were oxacillin agar screen (BBL: 80/86; Remel, Lenexa, KS: 85/50), DD (91/59), BMD (85/88), MicroScan (89/96), VITEK Legacy (82/93), VITEK 2 (91/73), and Phoenix, (67/96). These results suggest that a cefoxitin test can be used alone to predict mecA-mediated resistance in S. aureus.     

Unselective use of intranasal mupirocin ointment for controlling propagation of methicillin-resistant Staphylococcus aureus in a thoracic surgery ward

We executed a blanket-use program of intranasal application of mupirocin ointment to control the propagation of methicillin-resistant Staphylococcus aureus (MRSA) that occurred in a thoracic surgery ward of a university hospital. During an intervention of 14 weeks, all patients admitted to the ward for scheduled surgery received the ointment to their nares three times daily for 3 days before surgery, once on return to the ward, and three times weekly for the following 2 weeks. None of 84 patients was newly colonized with MRSA, and the daily rates of patients with MRSA in a recovery room in the ward significantly decreased in the period. We consider that the unselective application of mupirocin ointment is one of the effective measures to control MRSA propagation in a thoracic surgery unit.     

Adult methicillin-resistant Staphylococcus aureus bacteremia in Taiwan: clinical significance of non-multi-resistant antibiogram and Panton-Valentine leukocidin gene

It is poorly defined whether or not adult patients with methicillin-resistant Staphylococcus aureus (MRSA) bacteremia with a non-multi-resistant antibiogram phenotype and Panton-Valentine leukocidin (PVL) gene carriage have different clinical syndromes. Clinical characteristics of 95 adult patients of MRSA bacteremia, with isolates that were non-multi-resistant to non-beta-lactam, were compared with a contemporaneous multiresistant group. Independent risk factors other than community-associated MRSA bacteremia patients associated with recovery of non-multi-resistant MRSA isolates by multivariate analysis included deep-seated infection and catheter insertion site infection. Older age, intensive care unit-onset bacteremia, and postoperative infection were negative independent risk factors associated with non-multi-resistant MRSA isolates. Most of the 60 recoverable non-multi-resistant MRSA isolates belonged to multilocus sequence type 59, and all isolates belonged to staphylococcal chromosomal cassette mec (SCCmec) element type IV or type V. Most PVL-positive MRSA isolates belonged to SCCmec V. PVL-positive CA-MRSA isolates could cause more deep-seated infections in patients presented with non-multi-resistant MRSA bacteremia.