High frequency of Panton-Valentine leukocidin genes in invasive methicillin-susceptible <Emphasis Type="Italic">Staphylococcus aureus</Emphasis> strains and the relationship with methicillin-resistant <Emphasis Type="Italic">Staphylococcus aureus</Emphasis> in Córdoba,Argentina

In the study presented here, the genetic characteristics of methicillin-susceptible Staphylococcus aureus (MSSA) strains isolated from patients attending hospitals in the city of Córdoba, Argentina, during 1999–2002 were evaluated to determine their genetic relationship with methicillin-resistant S. aureus (MRSA) clones as part of an effort to control the potential emergence of new epidemic MRSA strains. The results showed there is a high frequency of MSSA strains carrying Panton-Valentine leukocidin genes in invasive infections in Córdoba, Argentina, particularly in those occurring in hospital settings. Panton-Valentine leukocidin genes were found in the genomic background of one clone (ST30-N pulsotype) belonging to a successful internationally distributed MSSA lineage (clonal complex 30), which is closely related to the EMRSA-16 pandemic clone. These genes were also detected in the ancestral clone (ST5-M pulsotype) of the most prevalent MRSA epidemic clone causing healthcare-associated infections in this region, known as the Cordobes/Chilean clone. The molecular characterization of circulating MSSA strains, including the detection of Panton-Valentine leukocidin genes, is thus a useful marker for investigating the evolving epidemiology of hospital- and community-acquired MRSA clones.     

Panton-Valentine leukocidin genes and staphylococcal chromosomal cassette <Emphasis Type="Italic">mec</Emphasis> types amongst Finnish community-acquired methicillin-resistant <Emphasis Type="Italic">Staphylococcus aureus</Emphasis> strains, 1997–1999

Methicillin-resistant Staphylococcus aureus (MRSA) strains from Finland covering years 1997–1999 were studied for the presence of Panton-Valentine leukocidin (PVL) gene loci, and the clinically well-defined community-acquired MRSA (CA-MRSA) strains (n = 108) also for staphylococcal chromosomal cassette mec (SCCmec) and multilocus sequence types (MLST). Only a minority (12%) of the CA-MRSA strains contained the PVL gene loci and possessed genotypes formerly described as typical to CA-MRSA strains. The majority of these strains were heterogenous by MLST and pulsed-field gel electrophoresis (PFGE) analysis but, however, harboured the SCCmec cassette type IV. In conclusion, it seems doubtful to consider only molecular characteristics such as the presence of PVL genes as definite markers for CA-MRSA strains. This data was partly presented at the 14th European Congress of Clinical Microbiology and Infectious Diseases (ECCMID), May 1–4, 2004, Prague, Czech Republic, Poster no. P1014.     

Outcome for invasive <Emphasis Type="Italic">Staphylococcus aureus</Emphasis> infections

We report a survey of invasive Staphylococcus aureus (ISA) infections concerning outcome variables such as mortality, recurrence and residual symptoms. A prospective, population-based study of all cases of ISA was conducted in the catchment area of Skaraborg Hospital (population 255,109) in western Sweden during the period from 1st March 2003 to 28th February 2005. One hundred and fifty-seven patients were included. Recurrences were seen in 13 cases (9.3%). Thirty patients (19.1%) died during the first 28 days. Mortality rates for complicated bacteraemia and severe sepsis were 32% and 54%, respectively. Older patients (>65 years of age), patients with concomitant heart disease and patients with endovascular infections all suffered higher mortality. Line-associated infections had a higher recurrence rate. Residual symptoms were common, with 34% of the living patients reporting incomplete recovery. Accessory gene regulator (agr) type within the bacteria did not affect disease presentation. We conclude that ISA infections are of major medical importance, with high rates of mortality (19.1%), recurrence (9.3%) and residual functional impairment (34%).     

Flucloxacillin treatment of <Emphasis Type="Italic">Staphylococcus aureus</Emphasis> meningitis

In this paper, we aimed to evaluate the efficacy of flucloxacillin treatment of meningitis caused by methicillin-sensitive Staphylococcus aureus. We identified 33 patients with meningitis due to S. aureus; eight had community-acquired meningitis and 25 had neurosurgical meningitis. Six of the eight patients with community-acquired meningitis were cured. Eighteen of the 22 patients treated with flucloxacillin were cured without relapse (86%, 95%CI 65–97%) and their cerebrospinal fluid (CSF) cultures were sterile after a median of 3 days of treatment. The cure rate for 12 patients who also received an additional antibiotic at the outset of treatment was 75% (95%CI 43–95%). This was not different to the cure rate for the ten patients who received flucloxacillin alone 90% (95%CI 56–100%). We conclude that flucloxacillin is an effective treatment for meningitis caused by S. aureus.     

SCC<Emphasis Type="Italic">mec</Emphasis> and <Emphasis Type="Italic">spa</Emphasis> types of methicillin-resistant <Emphasis Type="Italic">Staphylococcus aureus</Emphasis> strains in Israel. Detection of SCC<Emphasis Type="Italic">mec</Emphasis> type V

Molecular characterization of methicillin-resistant Staphylococcus aureus isolates from three hospitals in Israel was the aim of the study presented here. We identified 11 distinct genetic clones by pulsed-field gel electrophoresis. Molecular typing identified four different SCCmec types—I, II, IV, and V−and nine spa types. Spa type t002 was the most common. An erratum to this article can be found at     

Methicillin-resistant versus methicillin-sensitive <Emphasis Type="Italic">Staphylococcus aureus</Emphasis> infective endocarditis

The incidence of methicillin-resistant Staphylococcus aureus (MRSA) infective endocarditis (IE) is increasing. This study compared clinical characteristics and mortality in patients with methicillin-sensitive S. aureus (MSSA) IE versus MRSA IE, based on a prospectively collected series of 72 consecutive patients with definite S. aureus IE according to the modified Duke criteria between June 2000 and December 2006. Sixteen of 72 IE patients (22%) were caused by MRSA. Nosocomial origin, surgical site infection, surgery in the previous 6 months, the presence of a catheter and persistent bacteremia were significantly associated with MRSA. MSSA patients had significantly more unknown origin of bacteremia and experienced a significantly higher rate of major embolism than MRSA patients. MSSA patients underwent more frequently combined surgical and antimicrobial therapy, and MRSA patients were treated more frequently with antimicrobial therapy due to a contraindication to surgery. The 6-month mortality was higher in patients with MRSA than MSSA. In the MSSA group treated with antimicrobial therapy without an indication to surgery, all patients survived, and in the combined surgical and antimicrobial group 29% died. The mortality in MRSA patients was lowest if combined surgical and antimicrobial therapy was performed. Both in MSSA and MRSA patients with antimicrobial therapy due to a contraindication to surgery, the mortality was extremely high. These data suggest that in S. aureus IE patients with a nosocomial origin, the presence of a catheter or recent surgery, initial therapy should include antimicrobial agents active against MRSA. Antimicrobial therapy alone with close monitoring of the therapeutic effect and signs of complicated course is an acceptable approach in selected patients with MSSA IE. Denial of surgery because of local or general factors in patients that meet criteria for surgical intervention in acute IE is prognostically ominous.     

Rapid detection of Panton–Valentine leukocidin-positive <Emphasis Type="Italic">Staphylococcus aureus</Emphasis> by real-time PCR targeting the <Emphasis Type="Italic">luk</Emphasis>S-PV gene

In order to assess the speed and accuracy of a real-time PCR assay targeting the lukS-PV gene of Panton–Valentine leukocidin (PVL)-positive Staphylococcus aureus, 700 S. aureus strains were tested and the results were compared to those achieved with block cycler PCR. Cross-reactivity was tested with 166 other bacterial species. Using this homogeneous real-time PCR assay format, the presence or absence of genetic information for PVL, which is also found in community-associated methicillin-resistant S. aureus, was correctly identified from pure culture and directly in various types of clinical specimens.     

Complicating infectious foci in patients with <Emphasis Type="Italic">Staphylococcus aureus</Emphasis> or <Emphasis Type="Italic">Streptococcus</Emphasis> species bacteraemia

Complicating infectious foci resulting from haematogenous or local spread of microorganisms are observed frequently in patients with Staphylococcus aureus bacteraemia (SAB) or Streptococcus species bacteraemia (SSB). The aim of this study was to compare the epidemiology of complicating infectious foci during SAB and SSB in a university hospital in The Netherlands. The charts of all adult patients diagnosed with SAB or SSB (except for Streptococcus pneumoniae bacteraemia) from July 2002 until December 2004 were reviewed retrospectively. Overall, 180 immunocompetent patients were identified, 127 with SAB and 53 with SSB. The percentage of patients with complicating infectious foci (39% of SAB patients, 25% of SSB patients) did not differ significantly between the groups. Endocarditis and cerebral involvement, however, were significantly more common in the SSB group. Of all complicating infectious foci, 32% lacked guiding signs or symptoms and 10% were detected only at autopsy. Factors associated with the development of complicating infectious foci were a delay in treatment for more than 48 h after the onset of symptoms, community acquisition, persistently positive blood cultures, congenital heart disease, and the presence of foreign bodies or prosthetic valves. Infection-related mortality was 18% in SAB patients and 11% in SSB patients and was significantly higher in patients with complicating infectious foci (29 vs. 9%). In conclusion, complicating infectious foci develop in approximately one-third of all patients with SAB and SSB. An active approach that entails searching for the complicating infectious foci is warranted in these patients, because only two-thirds of complicated infectious foci have guiding symptoms or signs, and infection-related mortality is significantly increased in patients with complicating infectious foci compared to patients without these infections. Authors M.L.H. Cuijpers and F.J. Vos contributed equally to this work.     

Molecular epidemiology of <Emphasis Type="Italic">Staphylococcus aureus</Emphasis> in asymptomatic carriers

Microarrays were used to extensively characterise 155 Staphylococcus aureus isolates obtained from asymptomatic carriers from Saxony, Germany, in order to determine clonal complex affiliation, as well as the carriage of clinically relevant genes. Isolates belonged to 20 different clonal complexes (CCs). The most common CC was CC8 (18.71%), followed by CCs 15, 30 and 45. Three isolates (1.94%) were methicillin-resistant S. aureus (MRSA). Beta-lactamase was common (70.97%), but other resistance genes were found only sporadically. Genes encoding superantigens were abundant. The enterotoxin cluster egc was found in 45.81% of isolates. The toxic shock syndrome toxin gene tst was detected in 14.84% of isolates and 17.42% harboured enterotoxin A alleles (sea, sea-N315). Contrarily, Panton-Valentine leukocidin (lukS/F-PV) was rare, being found in only one methicillin-susceptible CC30 isolate. Its low prevalence in asymptomatic carriers might emphasise a pathogenetic significance in patients with skin and soft tissue infections. Most microbial surface components recognising adhesive matrix molecules of the host (MSCRAMMs) genes were nearly ubiquitously present. However, two MSCRAMM genes, cna (collagen adhesion) and sasG (surface protein G), were detected in only some CCs. These data provide an insight into its pathogenesis, especially when compared to isolates from patients with defined clinical conditions. They might also be helpful for the design of a future vaccine.     

Simultaneous real-time PCR detection of <Emphasis Type="Italic">Bacillus anthracis</Emphasis>, <Emphasis Type="Italic">Francisella tularensis</Emphasis> and <Emphasis Type="Italic">Yersinia pestis</Emphasis>

This report describes the development of in-house real-time PCR assays using minor groove binding probes for simultaneous detection of the Bacillus anthracis pag and cap genes, the Francisella tularensis 23 KDa gene, as well as the Yersinia pestis pla gene. The sensitivities of these assays were at least 1 fg, except for the assay targeting the Bacillus anthracis cap gene, which showed a sensitivity of 10 fg when total DNA was used as a template in a serial dilution. The clinical value of the Bacillus anthracis- and Francisella tularensis-specific assays was demonstrated by successful amplification of DNA from cases of cow anthrax and hare tularemia, respectively. No cross-reactivity between these species-specific assays or with 39 other bacterial species was noted. These assays may provide a rapid tool for the simultaneous detection and identification of the three category A bacterial species listed as biological threats by the Centers for Disease Control and Prevention.     

Serum procalcitonin has the potential to identify <Emphasis Type="Italic">Staphylococcus aureus</Emphasis> endocarditis

The role of procalcitonin (PCT) in the diagnosis of infective endocarditis (IE) remains unclear. The aim of our study was to test the accuracy of PCT in the early diagnosis of IE and analyse if the accuracy of PCT is dependent on the type of pathogen causing IE. We carried out a prospective analysis of hospitalised patients referred for transthoracic echocardiography to search for an IE. The plasma PCT value was measured at the time of echocardiography. The diagnosis of IE was made using the modified Duke criteria. A total of 77 patients were included. IE was confirmed in 15 patients. The mean PCT values were 6.9 (±21.6) ug/l in patients without IE and 6.4 (±11.7) ug/l in patients with confirmed IE (p=0.92). IE patients with Staphylococcus aureus bacteraemia (n=7) had significantly higher PCT values compared to IE patients with other types of bacteraemia (n=8) (13.1 vs. 0.435, p=0.0299). This study demonstrates that PCT levels markedly differ at the time when IE is diagnosed. While PCT values are very high in patients with S. aureus bacteraemia, they are surprisingly low in patients with Streptococcus viridans bacteraemia, which are common offenders of endocarditis. We conclude that serum PCT has the potential to be used in the early diagnosis of S. aureus endocarditis.     

Detection of <Emphasis Type="Italic">Ureaplasma</Emphasis> biovars and polymerase chain reaction-based subtyping of <Emphasis Type="Italic">Ureaplasma parvum</Emphasis> in women with or without symptoms of genital infections

Ureaplasma parvum colonises human mucosal surfaces, primarily in the urogenital and respiratory tracts, causing a wide spectrum of diseases, from non-gonococcal urethritis to pneumonitis in immunocompromised hosts. Although the basis for these diverse clinical outcomes is not yet understood, it has been suggested that only certain strains of these micro-organisms are disease-associated. The aim of this study was to determine the distribution of Ureaplasma biovars and U. parvum serovars and to estimate their possible association with age, absence of lactobacilli, clinical symptoms and antibiotic resistance. DNA was extracted by endocervical, vaginal and urethral samples obtained from 158 women positive for U. urealyticum by culture and were biotyped by polymerase chain reaction (PCR) targeting the multiple-banded gene. Parvo biovar (biovar 1) was found in 136 (86%) and T960 biovar (biovar 2) in 22 (14%) patients. Among the different serovars of U. parvum, we found that serovar 3/14 was present maximally in the 21–25-year-old age group, while T960 biovar was distributed with quite similar frequency in women of 26–30 and >40 years of age. In this study, U. parvum serovar 3/14 and T960 biovar were found to be significantly associated with symptomatic patients and a loss of lactobacilli, while, on the contrary, U. parvum serovar 6 was significantly correlated with asymptomatic women and normal vaginal flora. The most active antibiotic for the majority of Ureaplasma isolates was tetracycline. These preliminary data show the possibility of distinguishing between the more or less virulent strains of Ureaplasma, with important consequences for therapeutic treatment.     

Comparison of <Emphasis Type="Italic">SYBR Green I</Emphasis> and <Emphasis Type="Italic">TaqMan</Emphasis> real-time PCR formats for the analysis of <Emphasis Type="Italic">her2</Emphasis> gene dose in human breast tumors

We compared two technologies of real-time PCR (with the use of fluorescent SYBR Green I dye and specific TaqMan probe) for quantification of the dose of her2 gene in breast tumors. The maximum increase in the gene dose in TaqMan and SYBR Green I analyses was 10-and 5-fold, respectively. In was found that TaqMan and SYBR Green I technologies allow detection of the matrix in amounts corresponding to 1–100 and 2.5–40.0 ng genomic DNA, respectively. Tenfold increase in the gene dose leads to incorrect evaluation of multiplication ratio in the SYBR Green I analysis. These results suggest that TaqMan technology is more preferable for correct evaluation of her2 gene dose. __________ Translated from Byulleten’ Eksperimental’noi Biologii i Meditsiny, Vol. 145, No. 2, pp. 201–205, February, 2008     

Community-associated versus healthcare-associated methicillin-resistant <Emphasis Type="Italic">Staphylococcus aureus</Emphasis> bacteraemia: a 10-year retrospective review

The objective was to compare the epidemiology and outcome of healthcare- (HA-) and community-associated (CA-) MRSA bacteraemia. A 10-year retrospective study of MRSA bacteraemia was carried out. Episodes were classified according to established criteria. Molecular typing was performed on a subset of isolates. Of 197 MRSA bacteraemia episodes, 178 (90.4%) were classified as HA-MRSA and 19 (9.6%) as CA-MRSA. All-cause 7- and 30-day mortality rates were similar in the HA and CA-MRSA bacteraemia groups; however, 1-year mortality was higher in the HA-MRSA bacteraemia group (48.3% vs 21.1% [p = 0.023]). Thirty-day all-cause mortality was significantly lower if empiric antimicrobial therapy included agent(s) to which the isolate tested susceptible, compared with patients receiving “inactive” therapy (19% vs 35.1% [p = 0.011]). The majority of MRSA bacteraemia episodes were caused by clones known to circulate in the community. All-cause mortality is as high in HA- as in CA-MRSA bacteraemia. Thirty-day mortality was significantly reduced if the patient received an antibiotic with activity against the MRSA isolate. Results presented in part at the Interscience Conference on Antimicrobial Agents and Chemotherapy (ICAAC), Chicago, IL, 17–20 September 2007.     

<Emphasis Type="Italic">Trichomonas vaginalis</Emphasis> harboring <Emphasis Type="Italic">Mycoplasma hominis</Emphasis> increases cytopathogenicity in vitro

The parasite Trichomonas vaginalis causes one of the most common non-viral sexually transmitted infections in humans. Mycoplasmas are frequently found with trichomonads but the consequences of this association are not yet known. In the present study, the effects of T. vaginalis harboring M. hominis on human vaginal epithelial cells and on MDCK cells are described. The results were analyzed by light, scanning and transmission electron microscopy, as well as using cell viability assays. There was an increase in the cytopathic effects on the epithelial cells infected with T. vaginalis associated with M. hominis compared to T. vaginalis alone. The epithelial cells exhibited an increase in the intercellular spaces, a lesser viability, and increased destruction provoked by the infected T. vaginalis. In addition, the trichomonads presented a higher amoeboid transformation rate and an intense phagocytic activity, characteristics of higher virulence behavior.     

Mortality after infection with methicillin-resistant <Emphasis Type="Italic">Staphylococcus aureus</Emphasis>(MRSA) diagnosed in the community

Background  

Outbreak reports suggest that community-acquired methicillin-resistant Staphylococcus aureus (MRSA) infections can be life-threatening. We conducted a population based cohort study to assess the magnitude of mortality associated with MRSA infections diagnosed in the community.     

Effective quantitative real-time polymerase chain reaction analysis of the parkin gene (<Emphasis Type="Italic">PARK2</Emphasis>) exon 1–12 dosage

Background  

One of the causes of Parkinson's disease is mutations in the PARK2 gene. Deletions and duplications of single exons or exon groups account for a large proportion of the gene mutations. Direct detection of these mutations can be used for the diagnosis of Parkinson's disease.     

High rate of decreasing daptomycin susceptibility during the treatment of persistent <Emphasis Type="Italic">Staphylococcus aureus</Emphasis> bacteremia

Daptomycin is bactericidal against Staphylococcus aureus, with susceptibility defined as a minimal inhibitory concentration (MIC) < or =1 microg/ml. Higher MIC developed in a few cases during therapy. The frequency of MIC rise in persistent bacteremia is unknown. We evaluated all patients with S. aureus bacteremia (SAB) treated with daptomycin (> or =2 days) from 1 April 2004 to 30 October 2006. All patients with post-daptomycin-exposure saved isolates were studied. Daptomycin susceptibility was determined (in duplicate) on all pre- and post-daptomycin-exposure isolates by the broth (Mueller-Hinton) microdilution method. Among 74 treatment courses in 67 patients, 18 were for SAB. Ten had persistent bacteremia (median = 11 days; range = 1-21) and post-daptomycin-exposure saved isolates. The patient age was 29-84 years (median = 57.5 years). Intravascular catheter was the most common source (50%). Most patients (90%) failed therapy prior to starting daptomycin. The initial daptomycin dose was 4 mg/kg in four (40%) cases. The pre-exposure MIC was 0.125-0.5 microg/ml. The post-exposure MIC increased in four cases and was elevated in two cases (60%), to 2 microg/ml in five and 4 microg/ml in one. MIC rise was noted within 5-15 days of exposure and persisted up to 247 days after stopping daptomycin. Pulse-field gel electrophoresis (PFGE) band pattern of isolates with increased MIC revealed 1-3-band differences, implying genetic relatedness. All patients with non-susceptible isolates relapsed or failed therapy. These findings illustrate that daptomycin susceptibility often decreases during the treatment of persistent SAB. Therefore, susceptibility should be closely monitored during therapy.