Baudouin Byl

Interleukin-10 production during septicaemia

Interleukin-10 is produced during incubation of human whole blood with bacterial lipopolysaccharide (LPS) and down-regulates tumour necrosis factor-alpha production in this in-vitro model of endotoxaemia. 39 out of 69 (57%) patients with gram-negative (n = 25) or gram-positive septicaemia (n = 44) had increased plasma interleukin-10 (range 12-2740 pg/mL), whereas interleukin-10 was undetectable in 29 out of 33 control patients without infection and in 20 healthy volunteers. Patients with septic shock (n = 21) had higher interleukin-10 (main 58 pg/mL) than septicaemic patients without shock (11 pg/mL, p < 0.001). We conclude that interleukin-10 is produced during sepsis and might be involved in the control of the inflammatory response induced by bacterial products.

Impact of Infectious Diseases Specialists and Microbiological Data on the Appropriateness of Antimicrobial Therapy for Bacteremia

Antimicrobial therapy for 428 episodes of bacteremia in an 850-bed university hospital was prospectively evaluated for 1 year to measure the impact of two factors--blood culture results and the therapy chosen by infectious diseases specialists (IDSs)--on quality of treatment and outcome. Initial shock, a simplified acute physiology score of >15, and inappropriateness of the empirical treatment were independently associated with increased mortality. Empirical treatment was appropriate in 63% of the episodes. This proportion reached 78% for the episodes treated by IDSs, compared with 54% for the others (P < .001). After availability of blood culture results, the proportion of appropriate treatments increased to 94%, with 97% for IDS-treated patients and 89% for other patients (P = .008). IDSs more frequently shifted to oral antibiotics and used fewer broad-spectrum drugs. This study underlines the impact of blood culture results and of IDSs on the prescription of appropriate treatment for bacteremia and on the better use of antimicrobial drugs.

Tumor necrosis factor α and interleukin 6 plasma levels in infected cirrhotic patients

Abstract Background: Patients with liver cirrhosis disclose both increased production and decreased metabolism of tumor necrosis factor α (TNF-α) and interleukin 6 (IL-6). The present study analyzes the characteristic pattern of these cytokines during sepsis in cirrhotics. Methods: TNF-α and IL-6 plasma levels, measured during 15 days from the onset of cirrhotic decompensation or of the septic event, were compared between 14 infected patients with liver cirrhosis, 18 uninfected decompensated cirrhotic patients, and 35 septicemic patients devoid of liver disease. Cytokines were measured using immunoassays. Results: In infected cirrhotics, initial levels of both TNF-α and IL-6 were significantly higher than in noninfected cirrhotic patients ( P P Conclusions: Both the profoundly increased initial levels of TNF-α and IL-6 and their persistence over days after sepsis onset seem characteristic of the cirrhotic patients. The exact relationship between prolonged exposure to TNF-α and poor prognosis in these patients is unknown, but it might represent a unique opportunity for the use of anti-TNF-α antibodies during sepsis.

Molecular Characterization of an Epidemic Clone of Panantibiotic-Resistant Pseudomonas aeruginosa

ABSTRACT We describe the molecular characterization of a multiresistant Pseudomonas aeruginosa clone causing an outbreak in the intensive care unit (ICU) of a tertiary-care university hospital. Analysis included antimicrobial susceptibility profile, O-serotyping, pulsed-field gel electrophoresis, and amplified fragment length polymorphism. Resistance mechanisms were characterized, including production of naturally occurring and acquired β-lactamases, porin expression, and efflux pump systems. Eighteen patients were colonized or infected with multiresistant P. aeruginosa. Multiresistant P. aeruginosa was panresistant to penicillins, cephalosporins, carbapenems, aminoglycosides, and fluoroquinolones and remained susceptible only to colistin. Sixteen isolates (89%) belonged to serotype O:11, pulsed-field gel electrophoresis type A1, and amplified fragment length polymorphism type A. Resistance characterization of this epidemic clone showed an overexpression of the chromosomal cephalosporinase AmpC combined with decreased expression of porin OprD and the absence of metallo-β-lactamase or extended-spectrum beta-lactamase. An upregulation of the MexXY efflux system due to an agrZ mutation in the mexZ repressor was detected. This epidemic clone was restricted to the ICU and was not found elsewhere in hospital. Contamination of the ICU environment and the hands of an ICU nurse with this clone suggests possible hand-borne transmission. Implementation of contact precautions effectively controlled transmission of the epidemic clone. This study illustrates the ability of multiresistant P. aeruginosa to cause an outbreak with significant morbidity and mortality and underscores the need to identify clonal outbreaks, which require targeted infection control measures.

Fatal primary infection due to human herpesvirus 6 variant A in a renal transplant recipient.

We describe a fatal primary human herpesvirus 6 (HHV-6) variant A infection in a kidney transplanted adult woman. On day 20 post transplantation (TX), after rejection therapy, the patient presented an acute hemophagocytic syndrome with hepatitis and central nervous system involvement. HHV-6 IgG and IgM antibodies seroconversion was demonstrated. HHV-6 variant A was the sole pathogen detected by nested PCR and/or culture in blood, bone marrow aspiration, liver biopsy, cerebrospinal fluid and bronchoalveolar lavage. The graft was HHV-6 seropositive and the patient was not transfused before day 28 post TX, suggesting that the virus was transmitted by the graft. Despite immunoglobulins, ganciclovir and foscarnet therapy, the HHV-6 infection progressed and led to severe aplasia. The patient developed Aspergillus fumigatus pneumonia and died from fulminant candidemia. This case demonstrated for the first time that HHV-6 variant A primary infection can cause life-threatening disseminated infection in immunosuppressed patients.

Immune monitoring in whole blood using real-time PCR

There is a need for simple and sensitive assays to assess innate and adaptive immune responses to microbial agents and vaccines. Herein, we describe a whole blood method allowing to measure the induction of cytokine synthesis at the mRNA level. The originality of this method consists in the combination of PAXgene tubes containing an mRNA stabilizer for blood collection, the MagNA Pure instrument as an automated system for mRNA extraction and RT-PCR reagent mix preparation, and the real-time PCR methodology on the Lightcycler for accurate and reproducible quantification of transcript levels. We first demonstrated that this method is adequate to measure the induction of interleukin (IL)-1beta and IL-1 receptor antagonist (IL-1 RA) mRNA upon the addition of bacterial lipopolysaccharide (LPS) to whole blood. We then showed that this approach is also suitable to detect the production of mRNA encoding T cell-derived cytokines in whole blood incubated with tetanus toxoid as a model of in vitro immune response to a recall antigen. Finally, we demonstrated that this methodology can be used successfully to assess inflammatory as well as T cell responses in vivo, as it allowed to detect the induction of IL-1beta and IL-1 RA after injection of LPS in healthy volunteers, and also the induction of IL-2 upon recall immunisation with tetanus vaccine.

Intensive care unit outbreak of extended-spectrum β-lactamase- producing Klebsiella pneumoniae controlled by cohorting patients and reinforcing infection control measures

OBJECTIVE To describe an outbreak of extended-spectrum beta-lactamase (ESBL)-producing Klebsiella pneumoniae in the intensive care units (ICUs) of a hospital and the impact of routine and reinforced infection control measures on interrupting nosocomial transmission. DESIGN Outbreak report. SETTING A 31-bed intensive care department (composed of 4 ICUs) in a university hospital in Belgium. INTERVENTION After routine infection control measures (based on biweekly surveillance cultures and contact precautions) failed to interrupt a 2-month outbreak of ESBL-producing K. pneumoniae, reinforced infection control measures were implemented. The frequency of surveillance cultures was increased to daily sampling. Colonized patients were moved to a dedicated 6-bed ICU, where they received cohorted care with the support of additional nurses. Two beds were closed to new admissions in the intensive care department. Meetings between the ICU and infection control teams were held every day. Postdischarge disinfection of rooms was enforced. Broad-spectrum antibiotic use was discouraged. RESULTS Compared with a baseline rate of 0.44 cases per 1,000 patient-days for nosocomial transmission, the incidence peaked at 11.57 cases per 1,000 patient-days (October and November 2005; rate ratio for peak vs baseline, 25.46). The outbreak involved 30 patients, of whom 9 developed an infection. Bacterial genotyping disclosed that the outbreak was polyclonal, with 1 predominant genotype. Reinforced infection control measures lasted for 50 days. After the implementation of these measures, the incidence fell to 0.08 cases per 1,000 patient-days (rate ratio for after the outbreak vs during the outbreak, 0.11). CONCLUSION These data indicate that, in an intensive care department in which routine screening and contact precautions failed to prevent and interrupt an outbreak of ESBL-producing K. pneumoniae, reinforced infection control measures controlled the outbreak without major disruption of medical care.

Vancomycin Penetration of Uninfected Pleural Fluid Exudate after Continuous or Intermittent Infusion

ABSTRACT Blood and pleural exudate samples were obtained from 16 patients receiving intermittent or continuous infusions of vancomycin after lung surgery. The areas under the concentration-time curves for blood and pleural exudates were identical for both administration schedules, while continuous infusion allowed the concentrations in pleural exudates to be more sustained (mean concentration, 12 mg/liter).

Comparative Epidemiology of Staphylococcus epidermidis Isolates from Patients with Catheter-Related Bacteremia and from Healthy Volunteers

ABSTRACT Staphylococcus epidermidis is a major cause of catheter-related bloodstream infections (CRBSIs). Recent studies suggested the existence of well-adapted, highly resistant, hospital-associated S. epidermidis clones. The molecular epidemiology of S. epidermidis in Belgian hospitals and the Belgian community has not been explored yet. We compared a set of 33 S. epidermidis isolates causing CRBSI in hospitalized patients with a set of 33 commensal S. epidermidis isolates. The factors analyzed included resistance to antibiotics and genetic diversity as determined by pulsed-field gel electrophoresis (PFGE), multilocus sequence typing (MLST), and SCCmec typing. Additionally, the presence of virulence-associated mobile genetic elements, the ica operon and the arginine catabolic mobile element (ACME), was assessed and compared against clinical data. CRBSI S. epidermidis isolates were significantly resistant to more antibiotics than commensal S. epidermidis isolates. The two populations studied were very diverse and genetically distinct as only 23% of the 37 PFGE types observed were harbored by both CRBSI and commensal isolates. ACME was found in 76% of S. epidermidis strains, regardless of their origin, while the ica operon was significantly more prevalent in CRBSI isolates than in commensal isolates (P < 0.05). Nine patients presented a clinically severe CRBSI, eight cases of which were due to an ica-positive multiresistant isolate belonging to sequence type 2 (ST2) or ST54. S. epidermidis isolates causing CRBSI were more resistant and more often ica positive than commensal S. epidermidis isolates, which were genetically heterogeneous and susceptible to the majority of antibiotics tested. Clinically severe CRBSIs were due to isolates belonging to two closely related MLST types, ST2 and ST54.

Ceftazidime- and Imipenem-Induced Endotoxin Release During Treatment of Gram-Negative Infections

Abstract. To determine whether ceftazidime and imipenem, which target two different penicillin-binding proteins, result in different amounts of endotoxin and cytokine release in patients with gram-negative infection, plasma endotoxin, interleukin-6, and tumor necrosis factor alpha were measured during the first 24 h of antibiotic therapy in 27 patients with gram-negative infection who had been randomized to receive either ceftazidime 2 g t.i.d. (n=12) or imipenem/cilastatin 1 g t.i.d. (n=15). The source of infection was the digestive tract (n=13), the urinary tract (n=5), the respiratory tract (n=2), soft tissue (n=2), i.v. line (n=2), or other (n=3). After the first antibiotic injection, a significant increase in the median concentration of plasma interleukin-6 and plasma tumor necrosis factor alpha was noted, without significant differences related to the antibiotic administered. Antibiotic-induced endotoxemia was detectable in nine patients (including 7 with bacteremia). In conclusion, ceftazidime and imipenem had similar effects on endotoxin and cytokine release during the treatment of gram-negative infections.