Assia Ben Hassen

Prevention of central venous line-related thrombosis by continuous infusion of low-dose unfractionated heparin, in patients with haemato-oncological disease A randomized controlled trial

We have conducted a prospective randomized controlled trial to evaluate the role of low-dose unfractionated heparin prophylaxis in preventing central venous line-related thrombosis in patients with haemato-oncological disease. Patients were randomly assigned to receive either prophylactic intravenous unfractionated heparin (continuous infusion of 100 IU/kg/daily) or 50 ml/daily of normal saline solution as a continuous infusion. CVLs were externalized, non tunneled, double lumen catheters. All CVLs were placed percutaneously by the same physician in the subclavian vein. Upper limb veins were systematically examined by ultrasonography just before, or <24 hours after, catheter removal, and in case of clinical signs of thrombosis. One hundred and twenty-eight CVLs were inserted. Catheter-related thrombosis occurred in 1.5% of the catheters inserted in patients of the heparin group, and in 12.6% in the control group (p = 0.03). No other risk factors were found for the development of catheter-related thrombosis. Two and three patients experienced severe bleeding in the heparin group, and in the control group, respectively (p = 0.18). There were no other side-effects clearly ascribable to the use of unfractionated heparin. This is the first prospective, randomized study, which shows that low-dose of unfractionated heparin is safe and effective to prevent catheter-related thrombosis in patients with haemato-oncological disease.

Prevalence and Diversity of Integrons and Associated Resistance Genes in Escherichia coli Isolates from Poultry Meat in Tunisia

Fifty-five Escherichia coli isolates were acquired from chicken and turkey meat obtained from two slaughterhouses in Tunis. Eighty-nine percent, 80%, 78%, 67%, 45%, 27%, 7%, 4%, and 2% of these isolates showed resistance to tetracycline, trimethoprim/sulfamethoxazole, streptomycin, nalidixic acid, ampicillin, chloramphenicol, ciprofloxacin, colistine, and gentamicin, respectively. No resistance was detected to cefotaxime, ceftazidime, or amikacin. bla(TEM) gene was found in 22 of 25 ampicillin-resistant isolates, and 1 isolate harbored bla(OXA-1) gene. Tetracycline resistance was predominately mediated by the tetA gene. The sul1, sul2, and sul3 genes, alone or combined, were detected in 46 of 48 sulfonamide-resistant isolates, and sul1 and sul3 were included in class 1 integrons in some cases. Sixty percent of isolates harbored integrons (class 1, 30 isolates; class 2, 5 isolates). Class 2 integrons contained in all cases the dfrA1-sat1-aadA1-orfX gene cassette arrangement. Nine gene cassette arrangements have been detected among class 1 integrons, containing different alleles of dfrA (five alleles) and aadA (2 alleles) genes, which encode trimethoprim and streptomycin resistance, respectively. An uncommon gene cassette array (sat-psp-aadA2-cmlA1-aadA1-qacH-IS440-sul3) has been identified in three class 1 integron-positive isolates, and one additional isolate had this same structure with the insertion of IS26 inside the aadA1 gene (included in GenBank with accession no. FJ160769). The 55 studied isolates belong to the four phylogenic groups of E. coli, and phylogroups A and D were the most prevalent ones. At least one virulence-associated gene (fimA, papC, or aer) was detected in 44 of the 55 (80%) studied isolates. E. coli isolates of poultry origin could be a reservoir of antimicrobial-resistance genes and of integrons, and its evolution should be tracked in the future.

Genetic characterisation of CTX-M-15-producing Klebsiella pneumoniae and Escherichia coli strains isolated from stem cell transplant patients in Tunisia

Characterisation of extended-spectrum beta-lactamase (ESBL) genes and their genetic environments as well as the presence of integrons were analysed in nine Klebsiella pneumoniae and two Escherichia coli ESBL-positive isolates recovered in the Centre of Bone Marrow Transplantation of Tunisia. All strains harboured the bla(CTX-M-15) gene and presented minimum inhibitory concentrations for cefotaxime and ceftazidime of 256-1024 mg L(-1) and 16-512 mg L(-1), respectively, and eight of them showed different pulsed-field gel electrophoresis patterns. The bla(OXA-1) and bla(TEM-1) genes were detected in eight and ten strains, respectively. In addition, bla(SHV-1), bla(SHV-11) and bla(SHV-27) were found in six, one and one K. pneumoniae strains, respectively. The new variant bla(SHV-103) was characterised in one K. pneumoniae strain. The intI1 gene was detected in eight K. pneumoniae strains and the dfrA5+ereA2 and aadA gene cassettes were found in one and five strains, respectively. All strains harboured a 70 kb plasmid, and its transference in addition to bla(CTX-M-15), bla(TEM-1b) and bla(OXA-1) genes was demonstrated from three K. pneumoniae to E. coli. ISEcp1 and orf477 were located upstream and downstream, respectively, of the bla(CTX-M-15) gene in 10 strains. The occurrence of the bla(CTX-M-15) gene in unrelated strains might have originated from the dissemination of mobile genetic elements in which ISEcp1 may have played an important role.

Randomized Trial of Prevention of Catheter-Related Bloodstream Infection by Continuous Infusion of Low-Dose Unfractionated Heparin in Patients With Hematologic and Oncologic Disease

PURPOSE Infection is a serious complication of central venous catheters in immunocompromised patients. Catheter-related infection may be caused by fibrin deposition associated with catheters. Interventions designed to decrease fibrin deposition have the potential to reduce catheter-related infections. The purpose of this study was to evaluate the role of low-dose unfractionated heparin in preventing catheter-related bloodstream infection in patients with hemato-oncological disease. PATIENTS AND METHODS This study was a randomized, controlled trial in which patients with nontunneled catheters were randomly assigned to receive either intravenous unfractionated heparin (continuous infusion of 100 U/kg per day) or 50 mL/day of normal saline solution as a continuous infusion (control group). Heparin was continued until the day of discharge. Catheter-related bloodstream infection was defined according to Infectious Disease Society of America guidelines. RESULTS Two hundred and eight patients were randomly assigned. Four patients were excluded after assignment. Ultimately, 204 patients were analyzed. Catheter-related bloodstream infection occurred in 6.8% (7 of 102 catheters) of those in the heparin group (2.5 events per 1,000 days) and in 16.6% (17 of 102 catheters) of those in the control group (6.4 events per 1,000 days) (P = .03). No other risk factors were found for the development of catheter-related bloodstream infection. Four and five patients experienced severe bleeding in the heparin and control groups, respectively (P = .2). We did not observe heparin-induced thrombocytopenia. CONCLUSION The use of continuous infusion of low-dose unfractionated heparin (100 U/kg per day) can be a practical and economical approach to the prevention of catheter-related bloodstream infection in patients with hemato-oncological disease.

Hemophagocytic syndrome after hematopoietic stem cell transplantation: a prospective observational study

The aim of this prospective observational study was to evaluate the incidence of hemophagocytic syndrome (HPS) after hematopoietic stem cell transplantation (HSCT). Between July 2006 and December 2007, all patients who received a HSCT in our institution were included in this study. All the following criteria were needed for the diagnosis of HPS: sustained fever over 7 days; cytopenia (neutropenia and/or thrombocytopenia); presence of more than 3% mature macrophages in bone marrow; hyperferritinaemia (>1,000 ng/mL). During this study, 171 patients received a HSCT (68 allogeneic and 103 autologous). The median age was 32 years (3–62). We observed six cases of HPS (6/68; 8.8%) after allogeneic stem cell transplantation (ASCT): one case of EBV-related HPS, two cases of CMV-related HPS, and three cases with no evidence of bacterial, fungal or viral infections. We observed only one case of CMV-related HPS (1/103; 0.9%) after autologous stem cell transplantation. Four patients died despite aggressive supportive care. To our knowledge, this is the first prospective observational study conducted with the aim to evaluate the incidence of HPS after HSCT. This study provides a relatively high incidence of HPS after ASCT. When sustained fever with progressive cytopenia and hyperferritinaemia are observed, HPS should be suspected, and bone marrow aspirate considered. The rapid diagnosis of HPS and the early initiation of an appropriate treatment are essential for patient management.

Outbreak of Acinetobacter baumannii in a Neonatal Intensive Care Unit: Antimicrobial Susceptibility and Genotyping Analysis

PURPOSE We describe an outbreak of nosocomial respiratory infection caused by multi-drug resistant Acinetobacter baumannii in a neonatal intensive care unit (NICU) in Tunis and our investigation to determine the source. METHODS Between May 2006 and February 2007, 31 infants hospitalized in the NICU of the Centre of Maternity and Neonatology of La Rabta in Tunis developed A. baumannii pneumonia. A case (infected infant) was defined as any patient hospitalized in the NICU during the outbreak period, with clinical signs of pneumonia and isolation of A. baumannii from tracheal aspirate. Ten rectal swabs and 98 environmental specimens were collected for the epidemiological investigation. Thirty-nine A. baumannii isolates were collected: 31 clinical strains from tracheal aspirates (>10(3) colony-forming units [CFU]/mL), 3 environmental strains from incubators, and 5 from rectal swab. For the genotyping method, we used pulsed-field gel electrophoresis using ApaI restriction endonuclease. RESULTS Thirty-one neonates developed multiple drug-resistant A. baumannii-associated pneumonia with 10 deaths due to A. baumannii infection, 48.4% had very low birth weight (<or=1500 g), and 67.7% neonates were premature. The mean age at the beginning of symptoms was 6.9 days. A. baumannii isolates were resistant to all beta-lactams. Resistance rates to other antibiotics were, respectively, 94.9% for gentamicin, 87.2% for cotrimoxazole, 41% for netilmicin, and 5.1% for tobramycin. All the isolates were susceptible to colistin. Pulsed-field gel electrophoresis analysis of outbreak-isolates indicated the presence of only one clone (A) containing nine subtypes genetically related to the outbreak strain. CONCLUSION The clonal diffusion of A. baumannii strains in an NICU was confirmed by molecular method. Control measures were reinforced to contain the outbreak.

Molecular epidemiology of methicillin-resistant Staphylococcus hominis (MRSHo): low clonality and reservoirs of SCCmec structural elements.

Background Methicillin resistant Staphylococcus hominis (MRSHo) are important human pathogens in immunocompromised patients. However, little is known regarding its population structure and staphylococcal chromosomal cassette mec (SCCmec) content. Methodology/Principal Findings To assess the population structure and the SCCmec content of S. hominis, 34 MRSHo and 11 methicillin-susceptible S. hominis (MSSHo) from neutropenic patients collected over a 3-year period were studied. The genetic backgrounds of S. hominis isolates were analyzed by pulsed-field gel electrophoresis (PFGE) and SCCmec types were determined by PCR. Cassette chromosome recombinases (ccr) were characterized by PCR and ccrB sequencing. The 34 S. hominis isolates were classified into as many as 28 types and 32 subtypes (SID = 99.82%); clonal dissemination was occasionally observed. The main SCCmec structures identified were SCCmec type VI (4B) (20%), SCCmec VIII (4A) (15%), and a new SCCmec composed of mec complex A in association with ccrAB1 (38%); 27% of the isolates harbored non-typeable SCCmec. Overall, a high prevalence of mec complex A (73.5%), ccrAB1 (50%) and ccrAB4 (44%) were found. Importantly, ccrB1 and ccrB4 from both MRSHo and MSSHo showed a high nucleotide sequence homology with those found in S. aureus SCCmec I, VI and VIII respectively (>95%). Conclusions/Significance The S. hominis population showed a limited clonality and a low genetic diversity in the allotypes of ccr and classes of mec complex. Moreover, our data suggest that S. hominis might have been a privileged source of mec complex A, ccrB1 and ccrB4, for the assembly of primordial SCCmec types.

Strong biofilm production but not adhesion virulence factors can discriminate between invasive and commensal Staphylococcus epidermidis strains

Staphylococcus epidermidis is a leading cause of hospital‐acquired infections, mostly associated with the use of medical devices in immunocompromised patients. It originates from the patients own skin flora, which is subject to severe changes as a result of selective pressure exerted by the hospital environment. This notion led us to compare S. epidermidis isolates from catheter related infections (CRI), non‐catheter related bacteremia (NCRB) and catheter hub cultures (commensal isolates). The collection comprised 47 CRI strains from the Bone Marrow Transplant Centre of Tunis, 25 NCRB strains and 25 commensal isolates from patients hospitalized in the same center. Antimicrobial resistance and virulence‐associated genes (icaABC, aap, atlE, bhp, fbe, embp, and IS256), polysaccharide intercellular adhesin synthesis, and biofilm formation were investigated. The clonal relationship of strains was investigated by pulsed field gel electrophoresis. Whereas bhp, atlE, fbe, embp, and aap were almost ubiquitously amplified, resistance to oxacillin, kanamycin, tobramycin, gentamicin, cotrimoxazole, and fosfomycin, biofilm production, ica genes, and IS256 were significantly more frequent in invasive (CRI and NCRB strains) than in commensal strains. Moreover, strong biofilm production was significantly more frequent among CRI strains than in NCRB strains. In conclusion, when S. epidermidis is isolated from blood cultures, the detection of strong biofilm production may be significant with regard to judging whether the detected strain is an etiologic agent of CRI.

Successful treatment of fusarium solani ecthyma gangrenosum in a patient affected by leukocyte adhesion deficiency type 1 with granulocytes transfusions

BackgroundEcthyma gangrenosum (EG) manifests as a skin lesion affecting patients suffering extreme neutropenia and is commonly associated with Pseudomonas aeruginosa in immunocompromised patients. Leukocyte adhesion deficiency I (LAD I) which count among primary immunodeficiency syndromes of the innate immunity, is an autosomal recessive disorder characterized in its severe phenotype by a complete defect in CD18 expression on neutrophils, delayed cord separation, chronic skin ulcers mainly due to recurrent bacterial and fungal infections, leucocytosis with high numbers of circulating neutrophils and an accumulation of abnormally low number of neutrophils at sites of infection.Case PresentationWe report at our knowledge the first case of a child affected by LAD-1, who experienced during her disease course a multi-bacterial and fungal EG lesion caused by fusarium solani. Despite targeted antibiotics and anti-fungi therapy, the lesion extended for as long as 18 months and only massive granulocytes pockets transfusions in association with G-CSF had the capacity to cure this lesion.ConclusionWe propose that granulocytes pockets transfusions will be beneficial to heal EG especially in severely immunocompromised patients.

Prevalence of Mycoplasma pneumoniae-associated respiratory tract infections in hospitalized children: results of a 4-year prospective study in Tunis

Specific microbiologic, molecular, and serologic assays are hardly available in Tunis to confirm a suspected infection of Mycoplasma pneumoniae (MP). These diagnosis methods were used for the first time in a Tunisian prospective study to estimate the prevalence of MP infection in children and to evaluate their usefulness for diagnosis. A total of 540 children hospitalized in Tunis for lower respiratory tract infections (LRTIs) between 2005 and 2009 and 580 clinical specimens were investigated for the presence of MP by culture and by end-point polymerase chain reaction (PCR) targeting the P1 and the 16S rRNA genes. Real-time PCR was also used for MP detection on 158 respiratory samples. A total of 525 serum samples were tested for detection of MP-specific IgM and IgG. The P1 adhesin type and the antibiotic susceptibility testing were determined for the 9 clinical strains isolated during the study period. MP was detected in 33 (5.7%) clinical samples. Specific MP seropositivity was confirmed in 54 serum samples (10.3%), among which 19 (3.6%) were indicative of acute MP infection. MP infection was confirmed in 39 (7.2%) patients: 24 positive by PCR and/or culture, 10 serologically positive only, and 5 confirmed positive by both methods. MP infections occurred throughout the year with a slight decrease in autumn. The 9 MP isolates were susceptible to erythromycin, tetracycline, and ciprofloxacin, and all belonged to type I. The prevalence of MP infection in children with LRTI was 7.2% between 2005 and 2009, in Tunisia. Combination of direct detection and serology was required to enhance the clinical sensitivity of MP detection in clinical specimens.