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Biomedical subjects

A Hammami

Publications and source records attributed to A Hammami.

At least 19 recordsLinked to original sources
PubMed2006

Genetic environment of acquired bla(ACC-1) beta-lactamase gene in Enterobacteriaceae isolates.

We studied the genetic organization of bla(ACC-1) in 14 isolates of Enterobacteriaceae from France, Tunisia, and Germany. In a common ancestor, ISEcp1 was likely involved in the mobilization of this gene from the Hafnia alvei chromosome to a plasmid. Other genetic events involving insertion sequences (particularly IS26), transposons (particularly Tn1696), or sulI-type integrons have occurred, leading to complex genetic environments.

Base Sequence↗
PubMed2006

[Use of molecular subtyping methods to investigate two nosocomial outbreaks due to Salmonella Livingstone in Sfax hospital, Tunisia].

OBJECTIVE: The aim of the study was to investigate two nosocomial outbreaks due to Salmonella Livingstone in a pediatric ward in Sfax hospital using molecular typing techniques. MATERIALS AND METHODS: We included 84 strains of S. Livingstone isolated from patients hospitalized in a pediatric ward between November 1999 through August 2002 in addition to one environmental sample. Three epidemiological unrelated strains of S. Livingstone were also tested. The molecular typing techniques were: plasmid analysis, enterobacterial repetitive intergenic consensus (ERIC-PCR), random amplification of polymorphic DNA (RAPD-PCR) and pulsed field gel electrophoresis (PFGE). RESULTS: The plasmid analysis and the ERIC-PCR generated a similar profile for outbreak isolates including the environmental sample while the epidemiologically unrelated strains demonstrated distinct patterns. The RAPD-PCR applied on 20 strains showed three patterns but one profile was predominating. All the strains isolate of S. Livingstone, except the veterinary strain, could not be typed by PFGE. CONCLUSION: Using the molecular typing techniques, we showed that these two outbreaks in the pediatric ward were due to the clonal spread of a single strain of S. Livingstone. The identification of the source of contamination and the improvement of hygiene conditions are required.

Bacterial Typing Techniques↗
PubMed2006

[Bacteriology of community acquired meningitis in Sfax, Tunisia (1993-2001)].

OBJECTIVE: The aim of this study was to analyze the distribution of bacteria responsible for community-acquired meningitis and the pattern of resistance of common species. DESIGN: All bacteriologically confirmed cases of community-acquired meningitis were recorded between 1993 and 2001. RESULTS: Two hundred twenty-four cases of bacterial meningitis were recorded. The most frequent species were Haemophilus influenzae and Streptococcus pneumoniae followed by Neisseria meningitidis with respectively 37.1%, 32.1%, and 10.7% of cases. The yearly distribution of these bacteria did not show any epidemic peak. Enterobacteria and group B Streptococcus were the most frequently identified pathogens in neonatal meningitis. H. influenzae was the predominant microorganism in children between one month and five years of age, (66.4%) followed by S. pneumoniae (23.5%). S. pneumoniae was the predominant bacteria responsible fore more than half of the cases over five years of age. 28.8% of H. influenzae strains produced beta-lactamase. 27.2% of S. pneumoniae strains were less susceptible to penicillin. Resistance rates for amoxicillin and cefotaxime were respectively 10.6% and 7.5%. Only one strain of N. meningitidis (4.2%) presented with a decreased susceptibility to penicillin. CONCLUSIONS: In our study, H. influenzae and S. pneumoniae were the main microorganisms responsible for community-acquired meningitis. High resistance rates were found for these bacteria: 28.8% of H. influenzae to ampicillin and 27.2% of S. pneumoniae to penicillin.

Anti-Bacterial Agents↗
PubMed2006

[Contamination of blood cultures drawn from central vein catheter and peripheral venipuncture. Prospective study of 75 pairs].

OBJECTIVE: To determine the frequency of contamination, the sensitivity, specificity, and predictive values of cultures done with blood drawn through a central venous catheter or peripheral venipuncture. DESIGN: Prospective cohort study of critical ill medical surgical intensive care patients in whom samples for paired culture were drawn through a central venous catheter or peripheral venipuncture during a period of 8 months (from August 1st 2001 to Mars 31st 2002). RESULTS: During the study period, 75-paired cultures were studied. Fifteen peripheral blood cultures (20%) and 27 central blood cultures (36%) were positive and 6 peripheral blood cultures (8%) and 15 central blood cultures (20%) were contaminated (P=0.034). The organism most commonly responsible for contamination was Coagulase Negative Staphylococcus (16% of central blood cultures and 6.7% of peripheral blood cultures). The frequency of contamination was of 42.9% for blood cultures drawn through a femoral central venous catheter, of 10% for jugular, and of 19% for subclavian central venous catheter (P=0.22). For catheter draws compared with peripheral venipuncture, sensitivity was 100 and 75%, specificity was 76.2 and 90.5%, positive predictive value was 44.4 and 60% and negative predictive value was 100 and 95%. CONCLUSION: Cultures of blood drawn through a catheter are more sensible and less specific than those obtained from a peripheral venipuncture and the organism most commonly responsible for contamination of blood cultures is Coagulase Negative Staphylococcus.

Bacteria↗
PubMed2006

[Bacteriological profile of infectious endocarditis in the area of Sfax (Tunisia)].

We performed a study to analyze epidemiological characteristics and bacteriological profile of infectious endocarditis (I.E) in the area of Sfax (Tunisia). We analyzed, retrospectively, all cases of I.E, according to Duke Criteria, hospitalized in the CHU Hédi Chaker of Sfax between January 1997 and December 2000. Bacteriological investigation included blood culture, cardiac valve culture and serology. Seventy-two cases of I.E were diagnosed. The average of age was 32.3 years. 47.3% of the patients did not have cardiac disease, 25% had a valvular prosthesis, 20.8% a native valvulopathy and 6.9% a congenital cardiopathy. Antecedent of acute rheumatic fever was noted in 66% of I.E on native valvulopathy and in 55.5% of I.E on prosthesis. The mitral valve was involved in 39%, the aortic in 27.5% and the two in 26% of the cases. The origin of bacteremia was found or supposed in 55.5% of the cases and was commonly dental (33 % of EI). The bacteriological diagnosis was positive in 51 cases (70.8%). Staphylococci were isolated in 17 cases (23.6%), Streptococci in 17 cases (23.6%) and dominated by oral streptococci (12 cases). Chlamydial serology was positive in 8 cases (11.1%). Diagnosis of infectious endocarditis due to Chlamydia pneumoniae was confirmed in a case by genomic amplification (PCR) and in situ hybridization on the valve. Endocarditis in Tunisia remains frequent. It reaches with predilection the young person in particular with rheumatic heart diseases. The bacteriological profile remains dominated by Streptococci and the Staphylococci.

Adolescent↗
PubMed2005

[Predictive value of pericatheter skin cultures in detecting catheter-related infections in a medical-surgical intensive care unit].

OBJECTIVE: To evaluate the predictive value of pericatheter skin cultures in detecting catheter-related infections in critically-ill patients. STUDY DESIGN: Prospective study. PATIENTS AND METHODS: Over a 5 months period (from August 1(st) 2001 to December 31 2001), 500 patients were hospitalised, and 108 central venous catheters were prospectively examined. For each catheter, blood cultures, pericatheter skin cultures and semiquantitative culture of the catheter tip were performed. RESULTS: The median duration of catheterization was 8 days (interquartile: 8 days). Catheter was removed because of suspected infection in 54 cases (50%). Systemic catheter-related infection was found in 12 cases (11%) and the responsible organism was a gram-negative rod in 11 cases (92%). The negative predictive values of pericatheter skin cultures in the diagnosis of catheter-related infections and in case of suspected catheter-related infection were 89 and 86%, respectively. CONCLUSION: These results indicate that the pericatheter skin cultures are not an effective procedure for the conservative diagnosis of catheter-related infections and that the skin-insertion wound is not the major source of catheter-contamination in our unit.

Adolescent↗
PubMed2005

Comparison of three different serological techniques for primary diagnosis and monitoring of nasopharyngeal carcinoma in two age groups from Tunisia.

Nasopharyngeal carcinoma (NPC) in Tunisia is characterized by its bimodal age distribution involving juvenile patients of 10-24 years and adult patients of 40-60 years. Three serological techniques were compared for primary diagnosis (N = 117) and post-treatment monitoring (N = 21) of NPC patients separated in two age groups. Immunofluorescence assay (IFA) was used as the "gold standard" for detection of IgG and IgA antibodies reactive with Epstein-Barr virus (EBV) early (EA) and viral capsid (VCA) antigens. Results were compared with ELISA measuring IgG and IgA antibody reactivity to defined EBNA1, EA, and VCA antigens. Immunoblot was used to reveal the molecular diversity underlying the anti-EBV IgG and IgA antibody responses. The results indicate that young NPC patients have significantly more restricted anti-EBV IgG and IgA antibody responses with aberrant IgG VCA/EA levels in 78% compared to 91.7% in elder patients. IgA VCA/EA was detected in 50% of young patients versus 89.4% for the elder group (P < 0.001). Immunoblot revealed a reduced overall diversity of EBV antigen recognition for both IgG and IgA in young patients. A good concordance was observed between ELISA and IFA for primary NPC diagnosis with 81-91% overall agreement. Even better agreement (95-100%) was found for antibody changes during follow-up monitoring, showing declining reactivity in patients in remission and increasing reactivity in patients with persistent disease or relapse. ELISA for IgA anti-VCA-p18 and immunoblot proved most sensitive for predicting tumor relapse. VCA-p18 IgA ELISA seems suitable for routine diagnosis and early detection of NPC complication.

Adolescent↗
PubMed2005

Purification, amino acid sequence and characterization of Bacthuricin F4, a new bacteriocin produced by Bacillus thuringiensis.

AIMS: Purification and characterization of a new bacteriocin, Bacthuricin F4 of Bacillus thuringiensis. METHODS AND RESULTS: A newly isolated B. thuringiensis subsp. kurstaki strain BUPM4, was shown to produce a novel bacteriocin named Bacthuricin F4. The highest bacteriocin activity was found in the growth medium and evidenced in the late exponential growth phase. Bacthuricin F4 could be purified by a two-step procedure: ammonium sulphate precipitation of protein from culture supernatant followed by a reverse phase chromatography. Upon purification, the specific activity was increased 100-fold. This bacteriocin was heat-stable up to 70 degrees C and resisted up to pH 3.0. Bacthuricin F4 was sensitive to proteases demonstrating its proteinaceous nature. Its molecular mass, determined by mass spectrometry was 3160.05 Da. Direct N-terminal sequencing of Bacthuricin F4 revealed the following sequence: DWTXWSXL. The latter was unique in the databases. Bacthuricin F4 was active against Bacillus species while it had little or no effect on Gram-negative bacteria. CONCLUSIONS: A strain BUPM4 of B. thuringiensis subsp. kurstaki, was shown to produce a new bacteriocin named Bacthuricin F4 of both new molecular mass (3160.05 Da) and new amino acid terminal sequence. This is, to our knowledge, the first bacteriocin exhibiting such characteristics reported to be produced by B. thuringiensis. SIGNIFICANCE AND IMPACT OF THE STUDY: The bacteriocin produced by the B. thuringiensis strain BUPM4 respond to both criteria of thermostability and stability to low pHs. Thus, it could be used for the control of the related species of Bacillus harmful for agricultural products.

Amino Acid Sequence↗
PubMed2005

[Evaluation of the antibiotics consumption in a Tunisian university hospital].

PURPOSE: To estimate the consumption of antibiotics in our hospital and to determine the points at which will be targeted the recommendations of good practice of antibiotherapy. PATIENTS AND METHODS: Our study is a one day prevalence study where antibiotic's prescriptions are analyzed by a group of 6 doctors referents in antibiotherapy. RESULTS: During the study day, 443 patients were studied. Means age was 44.2 +/- 23.3 years (range: 1 and 102 years). 101 infections were diagnosed in 48 patients (10.8%). 192 patients (43.3%) received antibiotics. Antibiotherapy was curative in 44% of cases. The most prescribed antibiotics were gentamicin (85.2 DDD/1000 patients), metronidazole (79 DDD/1000 patients), and cefotaxime (73.9 DDD/1000 patients). According to the evaluation group, 30.7% of the antibiotic's prescription was considered unjustified. The antibioprophylaxis represents the category most often unjustified (49%). The molecules in which prescription was frequently considered unjustified are the ciprofloxacin (67%), the amoxicilline-clavulanate (40%) and the cefotaxime (40%). CONCLUSION: Our results suggest that an action of good practice should be targeted at the antibioprophylaxis and should concern especially molecules in which prescription was frequently unjustified.

Adolescent↗
PubMed2004

[Antimicrobial susceptibility and frequency of occurrence of clinical blood isolates in Sfax-Tunisia (1993-1998)].

Antimicrobial susceptibility and frequency of occurrence of clinical blood isolates in Sfax-Tunisia (1993-1998). The choice of antimicrobial therapy for the treatment of bacteremia is often empirical and based on the knowledge of susceptibility profiles of the most common bacteria causing such infections. This study determines the bacterial etiology of bacteremic episodes and antimicrobial susceptibility patterns recorded at a teaching hospital, from January 1993 to December 1998. We collected 2979 strains responsible for bacteremia. Gram negative bacteria were predominant (60%). The organisms recovered most frequently were Staphylococcus aureus (18.9%), Escherichia coli (14.7%), Klebsiella pneumoniae (14%) and Pseudomonas aeruginosa (7.6%). The incidence of resistance to methicillin were 17.4% for Staphylococcus aureus and 26.8% for coagulase negative Staphylococcus. No resistance to glycopeptides was observed among the enterococci and staphylococci studied. 27.7% of enterobacteriaceae were resistant to third generation cephalosporins. Imipenem was the most active agent against gram negative bacteria. To carry out a surveillance of bacteremic episodes occurring at every hospital, it is necessary to provide valuable information which should be the basis for effective empiric therapy.

Bacteremia↗
PubMed2004

Maintenance of pathogenicity during entry into and resuscitation from viable but nonculturable state in Aeromonas hydrophila exposed to natural seawater at low temperature.

AIMS: To investigate the fate of Aeromonas hydrophila pathogenicity when cells switch, in nutrient-poor filtered sterilized seawater, between the culturable and nonculturable state. METHODS AND RESULTS: Aeromonas hydrophila ATCC 7966, rendered non culturable within 50-55 days of exposure to marine stress conditions, was tested for its ability to maintain haemolysin and to adhere to McCoy cells. Results showed that pathogenicity was lost concomitantly with culturability, whereas cell viability remained undamaged, as determined by the Kogure cell elongation test. However, this loss is only temporary because, following temperature shift from 5 to 23 degrees C, multiple biological activities of recovered Aer. hydrophila cells, which include their ability to lyse human erythrocytes and to attach and destroy McCoy cells were regained. During the temperature-induced resuscitation, constant total cell counts were observed. Moreover, no significant improvement in recovery yield was obtained on brain-heart infusion (BHI) agar plates amended with catalase. We suggest that in addition to the growth of the few undetected culturable cells, there is repair and growth of some mildly injured viable but nonculturable cells. CONCLUSIONS: The possibility that nonculturable cells of normally culturable Aer. hydrophila in natural marine environment may constitute a source of infectious diseases posing a public health problem was demonstrated. SIGNIFICANCE AND IMPACT OF THE STUDY: These experiments may mimic what happens when Aer. hydrophila cells are released in natural seawater with careful attention to the conditions in which surrounding waters gradually become warmer in late summer/early autumn.

Aeromonas hydrophila↗
PubMed2004

Evaluation of a cefoxitin disk diffusion test for the routine detection of methicillin-resistant Staphylococcus aureus.

Two oxacillin disk methods were compared with a cefoxitin disk diffusion test for detection of methicillin-resistant Staphylococcus aureus (MRSA), with PCR for mecA as the reference method. When tested with 115 MRSA and 350 methicillin-susceptible S. aureus isolates, the cefoxitin disk test (specificity 100%, sensitivity 96.5%) was superior to the oxacillin disk methods (specificity 99.1%, sensitivity 90.4%). Testing with both oxacillin and cefoxitin disks would give better sensitivity (100%) than the cefoxitin test alone, but at the expense of specificity (99.1%). The cefoxitin disk test required no special test conditions and would improve the reliability of routine tests for detection of MRSA.

Anti-Bacterial Agents↗
PubMed2002

[Identification of plasmid-encoded cephalosporinase ACC-1 among various enterobacteria (Klebsiella pneumoniae, Proteus mirabilis, Salmonella) isolated from a Tunisian hospital (Sfax 997-2000)].

Because a multiresistant K. pneumoniae outbreak detected in an intensive care unit of a parisian hospital, combined to the production of the plasmid-encoded cephalosporinase ACC-1, a probable importation via a patient was suggested from another country (Tunisia). The investigation was conducted to examine 35 clinical strains of enterobacteria resistant to ceftazidime without synergy towards Augmentin. Other test of synergy with two inhibitors, BRL 42715, Ro 48-5545 was performed by diffusion method and deposit of 10 micrograms of inhibitor on disks containing ceftazidime, cefoxitin and cefotetan. Synergies were obtained suggesting a probable production of ACC-1 type among six isolates of K. pneumoniae (two), Proteus mirabilis (one) and Salmonella (three) issued from different units. The isoelectric focusing on gel revealed at least one band of beta-lactamase activity at 7.8 but also demonstrated the simultaneous production of several probable beta-lactamases including TEM-type, SHV-2 and ACC-1 among S. enterica ser. Livingstone. The PCR of the gene blaacc-1 was positive. The sequencing (1160 pb) of two products showed high identity (99-100%) with the gene blaacc-1 deposited in 1999. Finally the ACC-1 type reported in Tunisia was probably imported in France via a patient. Because a simultaneous synthesis of ESBL and ACC-1 type, its presence may be invisible and need more investigation.

Cephalosporinase↗
PubMed2002

Culture-negative endocarditis due to Chlamydia pneumoniae.

We report on the case of a 54-year-old woman diagnosed as having culture-negative endocarditis (clinical and histopathologic evidence compatible with a recent episode of endocarditis). The responsibility of Chlamydia pneumoniae in this episode of endocarditis was suggested by a serological study and was then confirmed by the positive results of PCR and in situ hybridization tests with aortic and mitral valves tissues. To our knowledge, this is the first case of endocarditis due to C. pneumoniae confirmed by molecular biology-based techniques.

Blood↗
PubMed2001

In nasopharyngeal carcinoma-bearing patients, tumors and lymphocytes are infected by different Epstein-Barr virus strains.

Despite the fact that most adult humans worldwide are latently infected by the Epstein-Barr virus (EBV), only a very small percentage of them will develop an EBV-associated malignancy. We do not know whether this situation reflects the existence of more sensitive individuals or of particularly tumorigenic EBV strains. We postulated that if highly tumorigenic EBV strains did exist, they would be preferentially found in consistently EBV-associated tumors, such as nasopharyngeal carcinoma (NPC), and differ significantly from the strains present in other, non-pathological sites of the same patients. To test this hypothesis, we compared the BNLF1 gene of the EBV strains present in tumors and in "reservoir lymphocytes" of 6 NPC-bearing patients from Tunisia. Our results show that all of these patients were infected by more than 1 (and up to 7) EBV strains. Moreover, lymphocytes and tumor cells from the same individual were systematically infected by different viral strains. The origin and biological significance of these multistrain infections are discussed.

Adult↗
PubMed2001

Detection of Chlamydia trachomatis in semen and urethral specimens from male members of infertile couples in Tunisia.

The sequelae to infection with Chlamydia trachomatis in women are an established cause of tubal infertility. However, little is known about chlamydial infection and male infertility. The main objective of this study was to evaluate the presence of asymptomatic C. trachomatis infections in urethral and semen specimens from the male members of infertile couples by means of four different methods: the direct fluorescence antibodies assay, cell culture, the Roche Cobas Amplicor polymerase chain reaction, and the presence of chlamydial local IgA antibodies by the recombinant antibody-enzyme-linked immunosorbent assay. One or more chlamydial infection markers were detected in 42 (45.7%) of the 92 examined urethral and semen specimens from the male partners of infertile couples. C. trachomatis was detected in 23.9% (22/92) of urethral specimens and in 35.9% (33/92) of semen specimens. Although there was a significant correlation between the detection of one or more chlamydial infection markers in urethral and semen specimens (p = 0.01), no significant correlation was found between the detection of C. trachomatis DNA in these samples. Furthermore, no significant association was found between the presence of chlamydial local IgA antibodies and the detection of C. trachomatis. The discrepancies in positive results found between some techniques for the detection of C. trachomatis in urethral and semen specimens might be explained by variations in the sensitivities and specificities of the tests carried out and the use of specimens from different anatomical locations. Our findings suggest that C. trachomatis seems to be widespread among the male partners of infertile couples in Tunisia. The detection of C. trachomatis in urethral or semen specimens can serve as a marker for the presence of this organism in the genital tract, which is not necessarily the cause of male infertility. The study of the correlation between the detection of chlamydial infection markers and the parameters of male fertility seems to be necessary in order to determine the direct link between chlamydial infection and male infertility and to choose the most efficient technique and most suitable specimen with which to diagnose C. trachomatis-associated male infertility.

Adult↗
PubMed2001

Chlamydia trachomatis and male infertility in Tunisia.

OBJECTIVE: Chlamydia trachomatis is a common sexually transmitted micro-organism. The impact of chlamydial infection on semen parameters and male fertility is controversial. Our purpose was to determine the prevalence of C. trachomatis in the male partners of infertile couples in Tunisia and to assess the relationship between chlamydial infection markers and male infertility. METHODS: Chlamydial DNA in urethral and in semen specimens was determined by using the Cobas Amplicor polymerase chain reaction (PCR) assay and chlamydial immunoglobulin G (IgG) antibodies were measured by micro-immunofluorescence in serum samples in 92 male partners, with or without pathological standard semen parameters, according to the guidelines of the World Health Organization (sperm count, progressive sperm motility, sperm morphology and sperm viability). In parallel, chlamydial infection markers in endocervical material were determined by PCR and chlamydial IgG antibodies were measured by micro-immunofluorescence in serum samples from the female partners of the patients. RESULTS: C. trachomatis was found in 35.9% (33/92) of the male partners of the infertile couples and in 38% (35/92) of their female partners. There was a significant correlation between the detection of C. trachomatis in both partners (p = 0.004). C. trachomatis DNA was detected in 18.5% (17/92) of urethral specimens and in 16.3% (15/92) of semen specimens. Chlamydial IgG antibodies were present in 9.8% (9/92) of the serum samples. A standard semen analysis showed that 88% (81/92) were pathological. Sperm viability, progressive sperm motility, morphology and sperm concentration were abnormal in 73.8%, 70.2%, 34.5% and 13%, respectively, of the 92 evaluated semen specimens. Comparison of the parameters of the standard semen analysis between the male partners of the infertile couples with or without chlamydial infection markers showed that only the presence of C. trachomatis DNA in semen samples can affect sperm motility. Parameters of the standard semen analysis were not significantly related either to the detection of chlamydial DNA in urethral samples or to the presence of serum chlamydial antibodies. CONCLUSION: Our results show that C. trachomatis seems to be widespread among the male partners of infertile couples in Tunisia and show that this organism can affect sperm motility and, thus, can play an important role in the etiology of male infertility.

Adult↗