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.

[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.

A bacteria-induced switch of sympathetic effector mechanisms augments local inhibition of TNF-alpha and IL-6 secretion in the spleen.

It is believed that an inflammation-induced activation of the CNS leads to an inhibition of overshooting immune responses to prevent extensive local cytokine secretion. However, immunosuppression by the sympathetic nervous system may be unfavorable when bacteria are present locally and when TNF-alpha is necessary to overcome infection. We now report in a superfusion model, using mouse spleen slices, that although local Pseudomonas aeruginosa increased splenic TNF-alpha and IL-6 secretion severalfold over basal levels, electrically released neurotransmitters attenuated cytokine secretion to similar basal level as under bacteria-free conditions. Bacteria reversed noradrenergic inhibitory effector mechanisms: Under bacteria-free conditions, TNF-alpha secretion was very low and IL-6 secretion was mainly inhibited by alpha2-adrenoreceptor ligation. In the presence of bacteria, TNF-alpha and IL-6 secretion were high and IL-6 secretion was mainly inhibited by beta-adrenoreceptor ligation. The alpha- to beta-adrenoswitch of IL-6 inhibition in the presence of bacteria was mediated by the prior adrenergic regulation of TNF-alpha. In vivo, chemical abrogation of sympathetic inhibition reduced accumulation of bacteria in the spleen, which depended at least in part on TNF-alpha. This suggests that activation of the sympathetic nervous system may be a forerunner for accumulation of bacteria in tissue and consecutively sepsis due to intensified inhibition of TNF-alpha secretion.

Improved detection of microorganisms by polymerase chain reaction in delayed endophthalmitis after cataract surgery.

OBJECTIVE: To evaluate whether the use of polymerase chain reaction (PCR) improves the identification of the causative pathogen in eyes developing delayed endophthalmitis after cataract surgery. DESIGN: Prospective, noncomparative case series. PARTICIPANTS: Consecutive series of 25 eyes with the clinical diagnosis of delayed endophthalmitis after cataract. MAIN OUTCOME MEASURE: Presence of bacterial or fungal DNA in aqueous humor and vitreous samples. RESULTS: In the aqueous humor the causative pathogen was identified in 84% (n = 21) of the eyes by PCR compared with 0% by diagnostic culture and 0% by microscopy. In the vitreous samples the pathogen was identified in 92% (n = 23) of the eyes by PCR compared with 24% by diagnostic culture (n = 6) and 0% by microscopy. CONCLUSIONS: PCR is useful for the identification of the causative pathogen in delayed endophthalmitis and had a higher rate of positive identification of the causative organism than microscopy or diagnostic culture.

[Effects of restrictions on use of vancomycin in a German university hospital]. / Erfahrungen mit der Beschränkung des Einsatzes von Vancomycin an einem deutschen Universitätsklinikum.

BACKGROUND: Recently, increasing antibiotic resistance has been observed among gram-positive bacteria. However, only few isolates were found to be resistant against glycopeptides. Therefore, internationally accepted guidelines recommend a restricted use of vancomycin and other glycopeptide antibiotics in order to prevent the development of resistance against these clinically important antibiotics. In many countries, the hospital pharmacies play a key role in control and reinforcement of antibiotic formulary restrictions. In Germany, however, the hospital pharmacies usually do not take over such control functions, and most wards keep a stock of regularly used drugs including antibiotics, which makes reinforcement of restrictions difficult. METHODS: In an attempt to achieve a restriction of vancomycin use, the pharmacy of our university hospital was advised to deliver vancomycin to the wards only on request with a special order form signed by an attending, individually for every patient who should receive vancomycin. The efficacy of this restriction measure was evaluated in 3-month periods before and after the restriction became effective. RESULTS: Hospitalwide, this led to a 20.1% reduction of i.v. vancomycin and an 85.7% reduction of oral vancomycin use per 1000 patient days. If the hematology/oncology units were not considered, the reduction of i.v. vancomycin use was 41.8%, and the total use after the restriction 24.2 g per 1000 patient days. Microbiology results which justified the use of vancomycin decreased by 8.3% (10.9% hematology/oncology units not considered) between the 2 observation periods. Assuming a 7-day mean course of i.v. vancomycin therapy, the empirical use of i.v. vancomycin decreased from 39.9% to 8% after the restriction had been instituted. CONCLUSION: Allowing only experienced physicians (attendings) to decide on the use of vancomycin therapy, proved in our experience to be an effective measure to reduce unnecessary vancomycin use.

Development and characterization of a murine monoclonal antibody reactive with a 64 kDa somatic antigen of Burkholderia cepacia.

Monoclonal antibodies (MAbs) to Burkholderia cepacia were produced from mice immunized with inactivated whole-cell antigen. For screening of resulting MAbs an enzyme-linked immunosorbent assay (ELISA) was used. A stable hybridoma cell line (BC-2) producing specific antibodies to a 64 kDa somatic antigen from B. cepacia was established. In ELISA and immunoblotting analysis the MAb BC-2 recognized all tested strains of B. cepacia whereas no cross-reaction with 32 Pseudomonas aeruginosa strains was found. From a wide range of other bacteria only strains of the species Burkholderia mallei, Burkholderia pseudomallei, and Burkholderia gladioli showed cross-reactions. The MAb BC-2 will be used to develop a diagnostic assay for the identification of B. cepacia and B. gladioli, important agents of nosocomial infections in immunocompromised patients suffering especially from cystic fibrosis (CF).

Diagnosis of infectious endophthalmitis after cataract surgery by polymerase chain reaction.

PURPOSE: To ascertain whether the use of the polymerase chain reaction (PCR) technique leads to more rapid diagnosis of infectious endophthalmitis after cataract surgery. SETTING: University Eye Clinic Regensburg, Germany. METHODS: The aqueous humor and vitreous of 16 eyes with infectious endophthalmitis (10 acute, 6 delayed) were evaluated by microscopy, diagnostic culture, and PCR to detect the infectious agent. RESULTS: Microscopy of the vitreous was positive in 3 eyes and the culture media results were positive in 7 eyes, all with acute endophthalmitis. Significantly fewer positive results were obtained in the aqueous humor. Using PCR, an infectious agent was detected in the aqueous humor of all 16 eyes and in the vitreous of 14. The vitreous sample was negative in 2 eyes with delayed endophthalmitis. CONCLUSIONS: Detection of the infectious agent was more successful using PCR than using conventional microbiological tests, especially in the diagnosis of delayed endophthalmitis where the pathogen was detected in the aqueous humor in all eyes.

Depression of tumor necrosis factor-alpha, interleukin-6, and interleukin-10 production: a reaction to the initial systemic hyperactivation in septic shock.

Sepsis remains a major cause of mortality in surgical intensive care units. Patients who survive the initial shock phase but die weeks later from multiple organ dysfunction still are a challenge to basic and clinical research. We addressed whether fulminant sepsis results in rapid changes (24 h) in the cellular capacity to produce cytokines in whole blood of septic patients on further stimulation after the initial systemic inflammatory response. Interleukin (IL)-6 plasma concentrations from 279 pg/mL to 5979 pg/mL confirmed the presence of a systemic inflammatory response. Anti-inflammatory IL-10 concentrations up to 275 pg/mL were detected, but there was no biologically active tumor necrosis factor-alpha (TNFalpha) detectable (by bioassay) at the time of investigation. On stimulation with Escherichia coli ex vivo, pro-inflammatory TNFalpha (130 pg/mL), IL-6 (4061 pg/mL), and anti-inflammatory IL-10 (711 pg/mL) production were markedly depressed in all patients compared with controls (2339 pg/mL, 50,319 pg/mL, and 9654 pg/mL, respectively). Septic shock resulted in early depression of the capacity for pro- and anti-inflammatory cytokine production. Monitoring of this effect, including its relationship to outcome, may offer a target variable for therapeutic efforts to maintain or restore adequate immune reactions to improve survival.

Induction of guinea pig airway hyperresponsiveness by inactivation of guanylate cyclase.

To examine the role of cyclic 3', 5'-guanosine monophosphate (cGMP) in airway responsiveness the effects of substances known to interfere with nitric oxide (NO) or cGMP were investigated on guinea pig airways. Using a perfused organ bath system, it was possible to apply the chemicals from either the serosal or the mucosal side independently. In addition, levels of intracellular cGMP were determined in tissues after various treatments. Sodium nitroprusside (a donor of NO), zaprinast (a specific inhibitor of cGMP phosphodiesterase) and 8-bromo-cGMP (8-Br-cGMP) caused a concentration-dependent relaxation of guinea pig trachea. These results indicate that cGMP is an important second messenger mediating tracheal relaxations. The above mentioned drugs caused a more profound relaxation when applied to the serosal side compared to the mucosal side, suggesting a barrier function of the epithelial layer. Incubation on the mucosal side of the tissues with 100 microM pyrogallol (a generator of superoxide that may inactivate NO) increased the contractile response to histamine at concentrations 0.3-3.2 microM (P < 0.05). Treatment of the preparations with 1 mM cystamine (an inactivator of guanylate cyclase) caused a 5-fold increase in the sensitivity to histamine (P < 0.05), indicating the involvement of the NO/cGMP pathway in the development of airway hyperresponsiveness. Incubation of the tissues with 100 microM histamine elevated the intracellular cGMP levels 10-fold; this effect was completely prevented by incubation of the tissues with methylene blue (a potent inactivator of guanylate cyclase). Mucosal incubation of the tracheal tubes with 10 microM methylene blue induced an 8-fold increase in sensitivity to histamine (P < 0.01) and the Emax was slightly increased. 25 min after instillation of 0.4 mumol methylene blue into the airways of anaesthetized guinea pigs, the lung resistance in response to histamine was elevated up to 395 +/- 82% (P < 0.001). The present study revealed that inactivation of NO or guanylate cyclase enhances the histamine-induced contractions of guinea pig tracheas. Therefore, it is suggested that the NO/cGMP pathway may be implicated in the pathogenesis of airway hyperresponsiveness and that drugs which enhance cGMP levels in airway smooth muscle may be of significance in the treatment of airway obstruction and enhanced reactivity.

Epithelium-derived linoleic acid metabolites modulate airway smooth muscle function.

Cultured epithelial cells obtained from guinea pig tracheal preparations metabolized arachidonic acid into 5- and 15-hydroxy-eicosatetraenoic acid and into the prostaglandins E2 and F2 alpha. Linoleic acid was converted by the epithelial cells into 9-hydroxy-octadecadienoic acid (9-HODE) and smaller amounts of 13-HODE. It was further investigated whether linoleic acid metabolites are of importance for the regulation of airway smooth muscle function. 13-HODE caused an increase of maximal contraction of tracheal rings to histamine, while 9-HODE had no effect.