Outbreak of leptospirosis during a scout camp in the Luxembourg Belgian province, Belgium, summer 2012.

An outbreak of leptospirosis occurred in the South of Belgium, during August 2012, in teenagers who participated in two consecutive adventure scout camps near the Semois river. Among the symptomatic patient population (ten scouts), clinical manifestations included headache (70%), myalgia (50%), fever (50%), bilateral conjunctival injection (50%), general malaise (30%), vomiting (20%), anorexia (20%) and cough (20%). Some of the cases presented elevated blood creatinine (40%), or proteinuria (30%). Three patients were confirmed by serology and one by polymerase chain reaction. Potential risk factors included direct contact with a muskrat and indirect contact with potentially contaminated environments including the river water. Prospective environmental investigation carried out near the river banks 2 weeks after the outbreak identified Ondatra zibethicus (muskrat) as one Leptospira sp. reservoir.

Actinomyces osteomyelitis in bisphosphonate-related osteonecrosis of the jaw (BRONJ): the missing link?

Bisphosphonate-related osteonecrosis of the jaw (BRONJ) is a rare complication of bisphosphonate treatment characterized by the development of exposed, necrotic bone in the jaw with inflammatory signs. The pathogenesis of BRONJ is not yet fully understood. This review analyzes the evidence supporting the hypothesis that BRONJ may be considered as a bisphosphonate-induced Actinomyces infection of the jaw according to the modified Koch's postulates. The main arguments relies on the following factors: (1) the high prevalence of isolation of Actinomyces from bone BRONJ lesions (73.2 % in retrospective series); (2) the similar pathological appearance of BRONJ and Actinomyces osteomyelitis in most studies, although BRONJ lesions without inflammation have been reported; (3) the high incidence of events that disrupt the normal mucosal barrier as a necessary trigger to develop BRONJ in bisphosphonate-exposed patients; (4) the predilection of bisphosphonate-induced osteonecrosis for the bones of the jaws; and (5) the favorable response of BRONJ on treatment that is active on Actinomyces. If BRONJ confirms to be a bisphosphonate-induced Actinomyces osteomyelitis of the jaw, this has major consequences for the prevention and treatment of this condition.

The pharmacokinetics and pharmacodynamics of vancomycin in clinical practice: evidence and uncertainties.

Vancomycin has been used extensively since the late 1950s. Despite the introduction of several new valuable anti-Gram-positive antibiotics during recent years and the waning susceptibility of staphylococci to vancomycin, it remains the gold standard for the treatment of bacteraemia caused by methicillin-resistant staphylococci. Vancomycin has clear dose-response and dose-toxicity correlations. It is widely accepted that these correlations are best predicted by the AUC/MIC model, with target levels of >400 being the clinical cut-off. The experimental base of this model is less robust than frequently believed, and several important issues in vancomycin resistance, such as biofilm resistance and the inoculum effect, are not included. Based on this model, current dosing guidelines propose intermittent dosing of vancomycin with target trough levels of 15-20 mg/L. Dose adaptations according to renal function have been proposed but are not yet validated. Clinical data also support the use of continuous infusion with target plateau levels of 20-25 mg/L, with similar efficacy at the cost of lower nephrotoxicity. Despite decades of intense clinical use and numerous studies and publications, the optimal dosing strategy for vancomycin reconciling the high needs of the dose-response relationship with the serious drawbacks of the dose-toxicity relationship remains to be established.

Successful treatment of renal AA amyloidosis in familial Mediterranean fever with pegylated alpha-2a interferon.

Renal AA amyloidosis is a severe consequence of chronic inflammatory diseases such as familial Mediterranean fever (FMF). FMF is caused by mutations in the MEFV gene, resulting in defective control of granulocyte-mediated inflammation. Interferon-alpha is known to induce MEFV expression in monocytes and granulocytes in vitro. We present the first case of colchicine-resistant FMF in which a durable disease remission and regression of renal amyloidosis was induced by chronic treatment with pegylated interferon-alpha.

Immunogenicity and safety of the 13-valent Pneumococcal Conjugate vaccine in 23-valent pneumococcal polysaccharide vaccine-naive and pre-immunized patients under treatment with chronic haemodialysis: a longitudinal quasi-experimental phase IV study.

OBJECTIVE: To benchmark the immunogenicity of pneumococcal conjugated vaccine (PCV-13) versus pneumococcal polysaccharide vaccine (PPV-23) in haemodialysis patients pre-vaccinated or not with PPV-23. METHODS: The study is a longitudinal quasi-experimental phase IV study in chronic haemodialysis patients aged ≥50 years. Total (ELISA) and functional (opsonophagocytic assay) antibodies after pneumococcal vaccination were quantified at baseline, and after 28 and 365 days. Of 201 eligible patients, 155 were included. Patients were divided in four groups. PPV-23 naive patients were randomized to PPV-23 (40) or PCV-13 (40) vaccination. PPV-23-pre-vaccinated patients were categorized as being vaccinated more (40) or less (35) than 4 years before the study and all received PCV-13. RESULTS: Patients among the four groups had a significant ELISA antibody response for most serotypes that remained significant up to day 365 versus baseline. In PPV-23-naive patients, ELISA antibody titres were significantly higher among PCV-13 versus PPV-23 recipients for six serotypes (1.85-2.34-fold) after 28 days, and remained significantly higher for one serotype (6A, 1.57-fold) after 365 days. Following PCV-13 vaccination, increase in ELISA antibody titres was significantly higher among PPV-23-naive versus PPV-23-pre-vaccinated patients for 12 serotypes after 28 days (1.68-7.74-fold) and remained significantly higher in ten serotypes (1.44-3.29-fold) after 365 days. CONCLUSION: Immune response after PPV-23 and PCV-13 remains significant for at least 1 year in non-PPV-23-pre-vaccinated patients. Among vaccine-naive haemodialysis patients PCV-13 seems more immunogenic than PPV-23. Immune response to PCV-13 is weaker in PPV-23-pre-vaccinated compared with vaccine-naive patients.

Tigecycline-induced inhibition of mitochondrial DNA translation may cause lethal mitochondrial dysfunction in humans.

BACKGROUND: A 65-year-old patient developed an unexplained and ultimately lethal metabolic acidosis under prolonged treatment with tigecycline. Tigecycline is known to have a selective inhibitory effect on eukaryotic mitochondrial translation. The underlying molecular mechanisms of the metabolic acidosis in this patient were explored. METHODS: Oxidative phosphorylation system (OXPHOS) analysis, blue native polyacrylamide gel electrophoresis followed by in-gel activity staining in mitochondria, molecular analysis of mitochondrial DNA (mtDNA) for genomic rearrangements and sequencing of the rRNA genes was performed on the subject's skeletal muscle. RESULTS: OXPHOS analysis revealed a combined deficiency of the complexes I, III, IV and V, with a preserved function of complex II (encoded by nuclear DNA), thus demonstrating a defective mtDNA translation. There were no known underlying mitochondrial genetic defects. The patient had a (m.1391T>A) variant within the 12SrRNA gene in heteroplasmy (50-60%). CONCLUSIONS: This patient developed an ultimately lethal mitochondrial toxicity while receiving prolonged treatment with tigecycline, which was caused by a defective translation of the mtDNA. Tigecycline is known to suppress eukaryotic mitochondrial DNA translation, but until now this effect has been considered to be clinically insignificant. The observations in this patient suggest a clinically significant mitochondrial toxicity of tigecycline in this patient, and warrant further investigation.

Diagnosis and treatment of Aspergillus flavus sternal wound infections after cardiac surgery.

We report the clinical data for 9 patients affected during an outbreak of Aspergillus flavus sternal wound infections after cardiac surgery. In 7 patients, the infection had a locally invasive character, with 3 of these patients having multiple relapses; 2 patients had fulminant mediastinitis and died. Most patients received combined surgical and medical treatment.

Reliability of the ica, aap and atlE genes in the discrimination between invasive, colonizing and contaminant Staphylococcus epidermidis isolates in the diagnosis of catheter-related infections.

OBJECTIVES: To evaluate the usefulness of detecting two genes involved in biofilm formation (icaA and aap) and one gene involved in initial adhesion (atlE) for discrimination between contaminant, colonizing and invasive Staphylococcus epidermidis isolates involved in catheter-related infections. PATIENTS: The first group contained 29 isolates that were isolated from the skin of healthy volunteers (contaminant isolates). The second group contained 16 isolates recovered from catheters (>1000 CFUs on quantitative catheter culture) from asymptomatic patients without bacteremia. These isolates were considered to be colonizing isolates. The third group contained 34 isolates grown in >or=2 different blood cultures from patients with a systemic inflammatory response. These isolates were considered to be invasive isolates. RESULTS: The prevalence of atlE did not differ between the three groups. The icaA and aap genes were significantly more prevalent in colonizing isolates (88% aap; 88% icaA) than in invasive isolates (68% aap, P = 0.179; 59% icaA, P = 0.055) and than in skin isolates (52% aap, P = 0.02; 38% icaA, P = 0.002). CONCLUSIONS: The high prevalence of aap and icaA in skin isolates and their higher prevalence in colonizing than in invasive isolates led to a low specificity when these genes were used to differentiate between contamination, colonization and invasive infection. We conclude that, although the prevalence of these genes differs in the three groups, their presence cannot be used for clinical decision-making.

Necrotizing fasciitis due to Streptococcus pneumoniae in a healthy 68-year old man: case report and review of the literature.

A case of pneumococcal necrotizing soft-tissue infection (NSTI) is described and 16 cases available in literature are reviewed. Pneumococcal NSTI seems to be the consequence of hematogeneous shedding of pneumococci, with frequent involvement of articulations. Furthermore, pneumococcal NSTI present like other NSTI, with a high mortality and the need for a combined surgical and medical therapy.

Quantification of expression of Staphylococcus epidermidis housekeeping genes with Taqman quantitative PCR during in vitro growth and under different conditions.

The aims of the present study were (i) to develop and test a sensitive and reproducible method for the study of gene expression in staphylococci and (ii) to study the expression of five housekeeping genes which are involved in nucleic acid metabolism (gmk, guanylate kinase; the dihydrofolate reductase [DHFR] gene), glucose metabolism (tpi, triosephosphate isomerase), and protein metabolism (the 16S rRNA gene; hsp-60, heat-shock protein 60) during in vitro exponential and stationary growth. A modified method for instant mRNA isolation was combined with gene quantification via Taqman real-time quantitative PCR. The detection limit of our method was 10 copies of RNA. The average intersample variability was 16%. A 10-fold increase in the expression of the hsp-60 gene was induced by exposure to a 10 degrees C heat shock (37 to 47 degrees C) for 10 min. During in vitro growth, the expression of all five housekeeping genes showed rapid up-regulation after inoculation of the bacteria in brain heart infusion medum and started to decline during the mid-exponential-growth phase. Maximal gene expression was 110- to 300-fold higher than gene expression during stationary phase. This indicates that housekeeping metabolism is a very dynamic process that is extremely capable of adapting to different growth conditions. Expression of the 16S rRNA gene decreases significantly earlier than that of other housekeeping genes. This confirms earlier findings for Escherichia coli that a decline in bacterial ribosomal content (measured by 16S rRNA gene expression) precedes the decline in protein synthesis (measured by mRNA expression).

The antibiotic and anti-inflammatory treatment of bacterial meningitis in adults: do we have to change our strategies in an era of increasing antibiotic resistance?

Community acquired bacterial meningitis remains a feared infection because of its high morbidity and mortality. During the last decade, the incidence and the microbial resistance patterns of pathogens causing bacterial meningitis have changed considerably. A sharp increase in meningococcal disease has been observed and meningitis caused by penicillin resistant Streptococcus pneumoniae emerged as a matter of major concern. Since pneumococcal resistance in Belgium to third generation cephalosporins remains rare and low level, addition of vancomycin to the initial empirical therapy including third generation cephalosporins is not yet necessary. However, the evolution of the resistance patterns of invasive S. pneumoniae should be followed very carefully. The emergence of penicillin resistant pneumococci also raises concern about the safety of adjuvant anti-inflammatory therapy with dexamethasone. Although there is a growing evidence suggesting a decrease of neurological complications after administration of adjuvant dexamethasone, this therapy may lower the already borderline penetration through the blood-brain barrier of the currently used antibiotics. This may result in therapeutic failure. We therefore presently do not advocate the routine use of dexamethasone in the therapy of adult bacterial meningitis.

New insights in the pathogenesis of foreign body infections with coagulase negative staphylococci.

Foreign body infections by coagulase negative Staphylococci are an important and growing problem in our hospitals. Only recently have we started to get some data on the specific virulence factors that permit the otherwise non-pathogenic Coagulase Negative Staphylococci (CNS) to be so successful in causing foreign body infections. Adherence of the Coagulase Negative Staphylococci to the foreign body is a first and crucial step. Several genes and gene-products have been identified that enhance staphylococcal adherence to biomaterials. Adherence is followed by accumulation; in this phase the Coagulase negative Staphylococci organise themselves into a complex multilayer of cells covered with polysaccharide. This we call the biofilm. Finally coagulase negative Staphylococci undergo complex and as yet non-defined metabolic changes that in combination with biofilm formation allow them to persist on the foreign body and become less susceptible to antibiotics. Few data are available on the factors involved in the accumulation and persistence phase.

Use of gDNA as internal standard for gene expression in staphylococci in vitro and in vivo.

An internal RNA standard proved less suitable in bacterial gene expression experiments. We therefore developed a method for simultaneous RNA and gDNA (genomic DNA) isolation from in vitro and in vivo samples containing staphylococci and combined it with quantitative PCR. The reliability of gDNA for bacterial quantification and for standardisation in gene expression experiments was evaluated. Quantitative PCR proves equivalent to quantitative culture for in vitro samples, and superior for in vivo samples. In gene expression experiments, gDNA permits a good standardisation for the initial amount of bacteria. The average interassay variability of the in vitro expression is 20.1%. The in vivo intersample variability was 73.3%. This higher variability can be attributed to the biological variation of gene expression in vivo. This method permits exact quantification of the number of bacteria and the expression of genes in staphylococci in vivo (e.g., in biofilms, evolution in time) and in vitro.

Antibiotic susceptibility and serotype distribution of 240 Streptococcus pneumoniae causing meningitis in Belgium 1997-2000.

Cerebrospinal fluid isolates of Streptococcus pneumoniae, collected during the years 1997-2000 at more than 100 Belgian laboratories were studied. The 10 most common serotypes-serogroups representing 76% of the isolates were 14, 6, 9, 19, 23, 18, 4, 10, 8 and 12 (in order of frequency). Thirty-six percent of strains were isolated in children < 5 years old. In this age group the number of serogroups was more limited and 81.4% are included in the 7-valent conjugate vaccine. Decreased susceptibility to penicillin was observed in 13.9% of 237 strains (MIC > 0.06 mg/L), with only 2.1% resistant strains (MIC > 1 mg/L). Twelve strains showed reduced susceptibility to cefotaxime (MIC > 0.5 mg/L). Only three of the 237 strains were intermediately susceptible to meropenem. All strains were susceptible to vancomycin and moxifloxacin. In Belgium, high doses of third generation cephalosporins remain effective for the treatment of pneumococcal meningitis. The new fluoroquinolones seem the most promising agents for the treatment of pneumococcal meningitis in the future.