Are histopathological findings of diagnostic value in native valve endocarditis?

BACKGROUND: Optimal management of infective endocarditis (IE) depends on the early detection of IE-causing pathogens and on appropriate antimicrobial and surgical therapy. The current guidelines of the European Society of Cardiology (ESC) recommend histopathological examination as the gold standard for diagnosing IE Habib et al. (Eur Heart J 30:2369-2413, 2005). We hypothesize that histopathological findings do not provide additional information relevant to clinical decision-making. METHODS: We retrospectively reviewed a cohort of patients who had undergone surgery for native valve endocarditis (NVE) at the University Hospital Regensburg between September 1994 and February 2005. All episodes of intraoperatively confirmed endocarditis during this period were included in the study. Data were retrieved from surgical records, microbiological and histopathological reports, and medical files of the treating as well as admitting hospital. Pathogens were correlated with the site of manifestation of the affected heart valve and with clinical and histopathological findings. RESULTS: A total of 163 episodes of NVE were recorded and entered into our study for analysis. The valves affected were the aortic valve (45 %), the mitral valve (28 %), the aortic and mitral valve (22 %), and other valves (5 %). IE-causing pathogens were Staphylococcus aureus (22 %), viridans streptococci (18 %), enterococci (10 %), streptococci other than Streptococcus viridans (9 %), coagulase-negative staphylococci (5 %), miscellaneous pathogens (4 %), and culture-negative endocarditis (33 %). Infection with S. aureus was associated with high rates of sepsis, septic foci, and embolic events, while patients with enterococcal IE showed the highest rate of abscesses. Mortality rate in all subgroups was low without significant differences. However, histopathological findings correlated poorly with the pathogen involved and showed only few significant associations that were without clinical relevance. CONCLUSIONS: The clinical presentation of IE depends on the pathogen involved. Among the episodes of NVE examined, the histopathological examination of resected heart valves did not show any pathogen-specific morphological patterns and therefore did not provide any additional information of clinical value. Based on our findings, we recommend complementary cultures of the resected materials (valve tissue, thrombotic material, pacer wire) and implementation of molecular diagnostic methods (e.g., broad-range PCR amplification techniques) instead of histopathological analyses of resected valve tissue.

Lack of evidence for persistent nasal colonization with community-acquired methicillin-resistant Staphylococcus aureus in a central European cohort.

One hundred and three patients who had previously tested positive for community-acquired methicillin-resistant Staphylococcus aureus (cMRSA) were followed up for a mean time of 32.6 months. Eighty patients had a history of skin or soft tissue infection, and the remainder were mostly asymptomatic carriers. Of 103 patients, only two reported ongoing symptoms with abscess formation. Of 81 nasal swabs available, 30.9% were positive for S. aureus but only four yielded Panton-Valentine leukocidin-positive methicillin-resistant S. aureus. In summary, we were unable to find persistent health issues or nasal colonization with cMRSA in a cohort of previously cMRSA-infected/colonized patients.

EEG in the FEAB model: measurement of electroencephalographical burst suppression and seizure liability in safety pharmacology.

INTRODUCTION: The purpose of this study was to explore the integration of electroencephalographical (EEG) measurements into the fentanyl/etomidate-anaesthetised Beagle (FEAB) model in order to detect burst suppression and/or seizure development caused by compounds, prior to new molecular entity (NME) declaration. Detecting such unfavourable side effects prevents their being found in conscious animals at a later stage of safety evaluation. In addition, this has the advantage of performing safety studies on the three vital organ systems (cardiovascular system, respiratory system and central nervous system) within one and the same animal model. METHODS: Dogs were anaesthetized and instrumented according to the FEAB model requirements, and in addition three needle electrodes were placed on the cranium and a one lead EEG signal was measured. The raw signal was analysed by the Narcotrend® (MonitorTechnik, Bad Bramstedt, Germany) for depth of anaesthesia registration, visually analysed for burst suppression ratio calculation after different anaesthetics (pentobarbital and etomidate), and spiking and seizure activity were quantified after intravenous administration of different proconvulsant agents: pentylenetetrazole (PTZ), bicuculline (BCC), bupropion (BUP) and pilocarpine (PIL). RESULTS: High doses of pentobarbital (60 mg/kg over 10 min) and etomidate (6 mg/kg over 10 min) induced dose-dependent burst suppression of 98 ± 2% and 61 ± 16%, respectively. Infusions of PTZ (1.5mg/kg/min), BCC (0.0625 mg/kg/min), BUP (0.5mg/kg/min) and PIL (5mg/kg/min) induced dose-dependent spiking and seizures: the thresholds were 34 ± 2, 0.15 ± 0.03, 10.0 ± 1 and 144 ± 9 mg/kg, respectively. In PTZ-treated dogs, spiking and seizures could be abolished with diazepam (2mg/kg i.v.) or with propofol (4 mg/kg i.v.). DISCUSSION: The present study showed that a one lead EEG can be used reliably in the FEAB model to estimate the depth of anaesthesia, and to detect burst suppression and seizure risk in safety pharmacology studies.

The Electro-Mechanical window: a risk marker for Torsade de Pointes in a canine model of drug induced arrhythmias.

BACKGROUND AND PURPOSE: In cardiovascular pharmacology, electrical and mechanical events can be distinguished, and the phrase 'electro-mechanical window' (EMw) describes the temporal difference between these events. We studied whether changes in EMw have potential predictive value for the occurrence of arrhythmias in fentanyl/etomidate-anaesthetized beagle (FEAB) dogs. EXPERIMENTAL APPROACH: The EMw was calculated as differences between the QT interval and QLVP(end) in FEAB dogs during atrial pacing, treatment with isoprenaline or atropine, body temperature changes and induction of Torsade de Pointes (TdP) in an LQT1 model. KEY RESULTS: The electrical systole (QT interval) was shorter than the duration of the mechanical event (QLVP(end) ), providing a positive EMw. Atrial pacing, atropine or body temperature changes had no major effects on EMw, despite large changes in QT duration. However, ß-adrenoceptor stimulation (with isoprenaline) decreased the EMw (from 90 to 5 ms) and in combination with HMR1556, a blocker of the slowly activating potassium current (I(Ks) ), induced a large negative EMw (-109ms) and TdP. Prevention of TdP by atenolol or verapamil was associated with a less negative EMw (-23 to -16ms). Mexiletine, a poorly effective long QT treatment, did not affect the EMw or prevent TdP induction. CONCLUSIONS AND IMPLICATIONS: The EMw is a marker, other than QT prolongation, of TdP risk in the FEAB model. Therefore, we suggest examining the EMw as a risk marker in cardiovascular safety studies and as a potential biomarker to improve clinical management of long QT syndrome patients, especially in patients with borderline QT prolongation.

Risk factors associated with long-term prognosis of patients with Staphylococcus aureus bacteremia.

OBJECTIVE: To estimate risk factors associated with long-term outcome (i.e., 1-year survival) in patients with Staphylococcus aureus bacteremia (SAB). METHODS AND MATERIALS: This was a retrospective study in which the microbiological laboratory data records of patients admitted to the University Hospital of Regensburg between January 2004 and June 2005 were examined to identify those patients with blood cultures positive for S. aureus. Corresponding clinical records for all patients were reviewed using a standardized questionnaire. Of the 119 patients identified with SAB, 80 were available for the >1-year follow-up. RESULTS: Crude 1-year mortality was 47.5; 30- and 90-day mortality was 28.8 and 37.5%, respectively. In-hospital mortality was 28.8%. There were no significant differences in 1-year survival in terms of age, gender, antibiotic resistance, and mode of acquisition (nosocomial vs. community-acquired). A significantly better survival was observed with an identifiable focus present, if the chosen empiric antibiotic therapy was adequate or if the body mass index of the patient was >24. CONCLUSION: In summary, in this patient cohort, considerable additional mortality due to SAB beyond 30 or 90 days was present. Our results suggest that long-term survival data should be taken into account in outcome studies involving patients with S. aureus bacteremia.

Splanchnic sympathectomy prevents translocation and spreading of E coli but not S aureus in liver cirrhosis.

INTRODUCTION: Spontaneous bacterial peritonitis (SBP) is mainly caused by bacterial translocation of enteric Gram-negative bacteria, predominantly Escherichia coli. The sympathetic nervous system (SNS) is activated in advanced cirrhosis, particularly in the splanchic circulation, and exerts potent immunosuppressive actions. However, the role of splanchnic SNS activity in bacterial translocation and bacterial spreading in cirrhosis remains unclear. METHODS: E coli or Stapylococcus aureus (10(6) CFU) were given intraperitoneally. After 6 h, mesenteric lymph nodes (MLN), liver, spleen, lung and peripheral blood were harvested from ascitic cirrhotic rats (LC) and healthy controls with and without splanchnic sympathectomy (SE). The bacterial tissue burden was determined by standard microbiological culture techniques. In vitro phagocytic activity of peritoneal polymorphonuclear leucocytes was assessed by FACS analysis. RESULTS: Under basal conditions SE reduced bacterial translocation to MLN in LC rats from 45% to 17%. LC rats had a marked increase in bacteraemia after E coli and S aureus challenge and an increased incidence and degree of E coli translocation to MLN, liver, spleen and lung compared with control rats. SE prevented bacteraemia in LC rats after E coli but not after S aureus challenge. Prior SE abolished the difference in incidence as well as the bacterial tissue burden in each organ after E coli application in LC rats, being no longer significantly different from control rats with or without SE. The protective effects of SE against E coli were associated with a greater influx of mononuclear cells into the peritoneal cavity and increased phagocytic activity of peritoneal polymorphonuclear leucocytes. CONCLUSIONS: In cirrhosis with bacterial peritonitis, hyperactivity of the splanchnic sympathetic nervous system contributes to the translocation of E coli but not S aureus to MLN and extraintestinal sites. This indicates a key role for sympathetic drive in the impairment in host defence against Gram-negative bacteria in cirrhosis.

Single-nucleotide polymorphism in the SCCmec-orfX junction distinguishes between livestock-associated MRSA CC398 and human epidemic MRSA strains.

A number of real-time PCR assays for direct detection of methicillinresistant (MRSA) in clinical specimens are targeting staphylococcal cassette chromosome mec (SCCmec) right extremity sequences and the S. aureus chromosomal orfX gene sequences located to the right of the SCCmec integration site. When testing 184 MRSA strains of human and animal origin from geographically distinct locations, we identified several characteristic single-nucleotide polymorphisms (SNPs) within the SCCmec-orfX junction of livestock-associated (LA) MRSA CC398 which serve as suitable strain markers for screening purposes. Within an assay time of 60 minutes and an additional 10 minutes for the melting curve analysis, all MRSA CC398 isolates were correctly identified by their characteristic T(m) value in the commercial LightCycler MRSA Advanced test. Studies to confirm the diagnostic accuracy of the SNP-based strain identification assay with a larger collection of clinical and LA-MRSA strains are ongoing.

[Treatment of lower limb osteomyelitis by a local bone substitute supplemented with antibiotics]. / Osteitisbehandlung an Unterschenkeln mit Knochenersatzmaterial als lokalem Antibiotikumträger.

A seriously injured tsunami victim with complicated osteomyelitis is presented. The patient was treated with a new resorbable bone substitute, which can be loaded with different antibiotics. The successful treatment is illustrated by the clinical, radiological and histological features. Bilateral open fractures of the lower leg with open elbow fracture led to a bilateral amputation of the lower legs and the right arm because of a beginning sepsis. The following intramedullary osteitis with multiresistant Pseudomonas aeruginosa, Escherichia coli and Enterococcus faecium was treated with the bone substitute PerOssal combined with systemic and local application of vancomycin and systemic application of ceftazidime and meropenem. This case report illustrates the concept of an additional local antibiotic treatment of osteomyelitis by a bone substitute also functioning as a drug delivery system.

The effect of changes in core body temperature on the QT interval in beagle dogs: a previously ignored phenomenon, with a method for correction.

BACKGROUND AND PURPOSE: Body core temperature (Tc) changes affect the QT interval, but correction for this has not been systematically investigated. It may be important to correct QT intervals for drug-induced changes in Tc. EXPERIMENTAL APPROACH: Anaesthetized beagle dogs were artificially cooled (34.2 degrees C) or warmed (42.1 degrees C). The relationship between corrected QT intervals (QTcV; QT interval corrected according to the Van de Water formula) and Tc was analysed. This relationship was also examined in conscious dogs where Tc was increased by exercise. KEY RESULTS: When QTcV intervals were plotted against changes in Tc, linear correlations were observed in all individual dogs. The slopes did not significantly differ between cooling (-14.85+/-2.08) or heating (-13.12+/-3.46) protocols. We propose a correction formula to compensate for the influence of Tc changes and standardize the QTcV duration to 37.5 degrees C: QTcVcT (QTcV corrected for changes in core temperature)=QTcV-14 (37.5 - Tc). Furthermore, cooled dogs were re-warmed (from 34.2 to 40.0 degrees C) and marked QTcV shortening (-29%) was induced. After Tc correction, using the above formula, this decrease was abolished. In these re-warmed dogs, we observed significant increases in T-wave amplitude and in serum [K(+)] levels. No arrhythmias or increase in pro-arrhythmic biomarkers were observed. In exercising dogs, the above formula completely compensated QTcV for the temperature increase. CONCLUSIONS AND IMPLICATIONS: This study shows the importance of correcting QTcV intervals for changes in Tc, to avoid misleading interpretations of apparent QTcV interval changes. We recommend that all ICH S7A, conscious animal safety studies should routinely measure core body temperature and correct QTcV appropriately, if body temperature and heart rate changes are observed.

[Multiple abscesses in immunocompetent patients caused by Panton-Valentine leukocidin positive Staphylococcus aureus]. / Multiple Abszesse bei immunkompetenten Patienten durch Panton-Valentin-Leukozidin-positiven Staphylococcus aureus.

We report cases of immunocompetent patients showing multiple abscesses by a Panton-Valentine leukocidin (PVL) positive Staphylococcus aureus. PVL is considered to be an important virulence factor. The most common manifestations by this pathogen are recurrent or multiple abscesses of the skin. Seldom necrotizing pneumonia with high mortality occurs. Even methicillin-resistant PVL positive isolates have been identified in Germany. Only appropriate infection control measures in combination with antimicrobial therapy resulted in successful eradication of this pathogen. Dermatologists should be informed about this specific type of infection and about the appropriate infection control measures.

Management of a large healthcare-associated outbreak of Panton-Valentine leucocidin-positive meticillin-resistant Staphylococcus aureus in Germany.

We report the largest documented healthcare-associated outbreak of Panton-Valentine leucocidin-positive meticillin-resistant Staphylococcus aureus (PVL(+) MRSA) in Europe. Six index patients from three long-term care facilities (LTCFs) were screened positive for PVL(+) MRSA in 2004 on admission to a community hospital in Germany. The purpose of this prospective study was to describe the prevalence of PVL(+) MRSA in the LTCFs before and after infection control interventions. Screening for MRSA with or without PVL was performed in all three LTCFs in 2004 [453 residents, 240 healthcare workers (HCWs)] and 2005 (440 residents, 192 HCWs). Swabs from anterior nares and wounds, if applicable, were collected. Colonised residents and staff were treated with mupirocin nasal ointment and topical antiseptics, and staff were provided with hygiene education. Total MRSA carrier rate of residents and HCWs in 2004 was 11.3% (PVL(+) MRSA 9.1%, PVL(-) MRSA 2.2%). There were comparable carrier rates between residents and HCWs in each LTCF. All PVL(+) MRSA isolates were of clonal origin (MLST 22) representing a novel spa sequence type t310. A decrease in total MRSA prevalence (from 11.3 to 5.5%) and PVL(+) MRSA (from 9.1 to 3.3%) was observed in 2005. The rate of PVL(-) MRSA remained unaffected. No symptomatic skin infections were noted among residents or HCWs. In this outbreak incomplete control of PVL(+) MRSA presumably resulted from difficult and delayed detection and decolonisation of carriers, incomplete compliance with control measures and lack of enforcement by public health authorities.

Comparative genomics and DNA array-based genotyping of pandemic Staphylococcus aureus strains encoding Panton-Valentine leukocidin.

Within the last few years, methicillin-resistant Staphylococcus aureus (MRSA) strains encoding Panton-Valentine leukocidin (PVL) have emerged and spread worldwide. This epidemic can be attributed to a small number of distinct clones. The present study used a novel assay, based on multiplex linear DNA amplification and subsequent microarray hybridisation, to simultaneously detect all relevant exotoxins, antimicrobial resistance determinants and the allelic variants of agr. The genes of the staphylococcal exotoxin-like (set) locus were also included for typing purposes. This assay, together with multilocus sequence typing (MLST) and spa typing, was applied to 56 clinical isolates and reference strains representing all major pandemic PVL-MRSA lineages, as well as to phylogenetically-related strains and putative ancestors. Array hybridisation results allowed the assignment of isolates to clonal groups, which were in accordance with MLST and spa typing data. Ten distinct clonal groups of PVL-MRSA (ST1, ST5, ST8, ST22, ST30, ST59/359, ST80/583, ST88, ST93 and ST152), including 12 MLST types, were identified and analysed with regard to resistance determinants and genes coding for exotoxins. The array hybridisation data confirmed that pandemic PVL-positive strains originate from very diverse genetic backgrounds, and provided insights into the evolution of some lineages. The DNA microarray technique provides a valuable epidemiological tool for the detailed characterisation of clinical isolates and comparison of strains at a global level.

Low rate of clinical consequences derived from results of blood cultures obtained in an internal medicine emergency department.

BACKGROUND: Blood cultures detect bacteremia in individual patients and help define local pathogen and resistance spectra. At the same time, the benefits of blood culture results in the management of individual patients -- and therefore their cost-effectiveness -- are disputed. PATIENTS AND METHODS: During 1 calendar year, we conducted a prospective study of emergency department admissions with blood culture draws and at least a 3-day hospitalization afterwards. We prospectively surveyed treating physicians on usefulness of blood culture results for patient management. RESULTS: 428 diagnostic episodes (emergency visits) involving 390 patients occurred during the study period from 10/2002 to 10/2003. The analysis included 188/428 (44%) episodes with blood culture draws performed according to the predefined clinical standard where patients were hospitalized with sufficient duration. Absence of therapeutic consequences in response to blood culture results was reported for 138/142 (97%) of episodes with negative blood culture results, for 16/21 (76%) with blood culture results positive only for skin flora, and for 14/25 (56%) of episodes with blood cultures positive for obligate pathogens. Treating physicians regarded the blood culture results necessary for clarifying the etiology in 34/188 (18%) episodes, and rated blood culture results necessary for their therapeutic decisions in 29/188 (15%) episodes. CONCLUSION: Negative blood culture results rarely changed the management of medical inpatients. Our study suggests that in settings with broad-spectrum empirical antibiotic therapy positive blood culture results for obligate pathogens trigger adjustment of the antibiotic therapy in only about half of instances. Many blood cultures drawn in the emergency department where considered unnecessary by ward physicians. Guidelines for preventing unnecessary blood culture draws are warranted in order to increase the rate of their meaningful clinical consequences for medical inpatients initially treated with broad-spectrum empirical antibiotics.

Primary cutaneous cryptococcosis and secondary antigenemia in a patient with long-term corticosteroid therapy.

We report a case of a 71-year-old male who developed severe cellulitis of his right forearm and hand after he had an accidental injury from the sharp edge of a metal plate of a birdhouse. The patient suffers from chronic asthma and has been treated with systemic corticosteroids for years. Culture of aspirates from two sites of the wound area revealed growth of Cryptococcus neoformans in one and Acinetobacter lwoffii in the other. After combined treatment including antibiotics, antifungal therapy with fluconazole 400 mg/d and surgical debridement followed by a mesh graft, the patient achieved complete healing of the wound. Five months after the infection, the patient was still positive for cryptococcal antigen at a titer of 1:64 despite oral treatment with fluconazole 50 mg/d, and maintenance therapy with fluconazole 200 mg/d was recommended for 6 months, or longer depending on further results. The clinical and microbiological characteristics of this patient as well as therapeutical and epidemiological aspects of primary cutaneous cryptococcosis (PCC) are discussed.

Emergence of methicillin-resistant Staphylococcus aureus with Panton-Valentine leukocidin genes in central Europe.

The aim of the present study was to investigate strains of methicillin-resistant Staphylococcus aureus (MRSA) for the presence of the lukS-lukF determinant of Panton-Valentine leukocidin and to further characterize strains found to contain the genes. During the past 2 years, MRSA containing the lukS-lukF genes for Panton-Valentine leukocidin, particularly those emerging outside of hospitals, have become of interest. MRSA strains sent to the national reference center in Germany were investigated for lukS-lukF by polymerase chain reaction (PCR). If the presence of lukS-lukF was demonstrated, strains were further characterized by molecular typing (determination of SmaI pattern, spa sequence, and multilocus sequence type), PCR demonstration of resistance genes, and characterization of the SCCmec element. Since the end of 2002, MRSA containing Panton-Valentine leukocidin genes have been demonstrated as the causative agent of 28 cases of infection (9 community-acquired cases, 19 sporadic nosocomial cases) in different areas of Germany. Twenty-seven of these 28 isolates exhibited a unique pattern of genomic typing: all exhibited multilocus sequence type 80, spa sequence type 44, and a SmaI macrorestriction pattern that corresponds to a community-acquired strain of MRSA from France and Switzerland. In addition to resistance to oxacillin, the strains exhibited resistance to ciprofloxacin, tetracycline (tetM), and fusidic acid, the last of which is encoded by the far-1 gene. The far-1 gene was shown to be located on the plasmid. One isolate corresponded to community MRSA (cMRSA) of multilocus sequence type 1 from the USA.

Factors that determine acetylcholine responsiveness of guinea pig tracheal tubes.

Acetylcholine administered to the inside of epithelium-denuded tracheal tubes did cause a potent contraction (2486+/-120 mg). In contrast, a response was hardly observed in tissues with an intact epithelial layer (674+/-81 mg), which was due to both the synthesis of nitric oxide and the activity of acetylcholinesterase, since the contractions to acetylcholine were significantly enhanced after preincubation with N(omega)-nitro-L-arginine methyl ester (L-NAME) or physostigmine (1374+/-65 and 1120+/-65 mg, respectively). In addition, the suppressive effect was caused by the barrier function of the epithelial layer, since preincubation of epithelium-denuded tissues with physostigmine significantly increased the pD2 value for acetylcholine (7.48+/-0.04) compared to intact tissues preincubated with physostigmine (6.32+/-0.10) and epithelium-denuded preparations without physostigmine (6.37+/-0.06). Increasing concentrations of physostigmine administered to the inside of tissues with epithelium did induce a potent spontaneous contraction (1440+/-350 mg) that was prevented by atropine. In contrast to what was expected, the contractile response was diminished in tracheal tubes without epithelium (665+/-221 mg). It is concluded that contractions of epithelium-denuded tissues are more pronounced to exogenous than to endogenous acetylcholine, and that the production and breakdown of this neurotransmitter is very rapid in intact guinea pig airways. Moreover, the release of nitric oxide and the barrier function of the epithelium did suppress the responsiveness to acetylcholine.