[Show abstract][Hide abstract] ABSTRACT: Twenty-three strains of Staphylococcus aureus with borderline resistance to oxacillin were studied. These strains were not detected by the cefoxitin test, tests for penicillin-binding protein 2a (PBP2a), mecA, and mecA(LGA251) were negative, and the strains were genetically unrelated. To detect all strains resistant to oxacillin, laboratories should routinely test for both cefoxitin and oxacillin.
Journal of clinical microbiology 07/2012; 50(10):3345-8. · 4.16 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: The authors had for aim to monitor Enterobacteriaceae resistance to colistin, during 6 years (2005-2010), and to study the epidemiology of Enterobacteriaceae resistant strains isolated in the Sfax region (Tunisia).
This retrospective study was carried out in the microbiology laboratory, at the Habib Bourguiba teaching hospital in Sfax. All strains of colistin resistant Enterobacteriaceae isolated from patients were studied.
One hundred and twenty one strains of colistin resistant Enterobacteriaceae were isolated from 93 patients. Klebsiella pneumoniae was the most frequent species (60.2%), followed by Enterobacter cloacae (26.9%), and Escherichia coli (12.9%). Thirteen strains (E. cloacae) were heteroresistant to colistin. Eighty one isolates (87.1%) were resistant to third generation cephalosporins. The rate of resistance to colistin ranged from 0.09% for E. coli to 1.2% for K. pneumoniae, and 1.5% for E. cloacae. A progressively increasing colistin resistance was observed for K. pneumoniae. Most resistant strains were isolated from urine in the urology department. Previous exposure to colistin was reported in 59.2% of patients. Pulsed field gel electrophoresis typing revealed different clones.
Colistin resistance in Enterobacteriaceae is a worrying phenomenon in Sfax. It is related to polyclonal diffusion. Continuous epidemiological monitoring and a rational use of colistin are necessary to limit the spreading of these colistin resistant strains and to maintain this antibiotic's effectiveness.
[Show abstract][Hide abstract] ABSTRACT: AIM: We report the emergence of Staphylococcus aureus resistant to pristinamycin in Tunisia, and the characterization of the mechanisms of resistance to macrolides and streptogramins. METHODS AND RESULTS: Five strains of S. aureus resistant to pristinamycin were recovered from the department of dermatology in a Tunisian university hospital from skin samples after oral use of pristinamycin between 2004 and 2007. Susceptibility testing showed that all isolates were resistant to quinupristin-dalfopristin (MIC=4-32mg/L), lincomycin, gentamicin, kanamycin, tobramycin, tetracycline and rifampin. One isolate was susceptible to erythromycin. All five strains were closely related after analysis by pulsed-field gel electrophoresis. erm(C) was amplified from three strains and erm(A) from one strain. vga and vat genes were amplified from all strains. None of the isolates carried the vgb gene. The vga and vat genes were typed as vga(B) and vat(B) by restriction profiles analysis after electrophoresis. CONCLUSION: This is the first report of clonal emergence of S. aureus resistant to pristinamycin carrying vga and vat genes in Tunisia. The role of selective pressure of pristinamycin use is certainly the main explanation of this emergence. So we must reduce the utilisation of this antibiotic for the treatment of cutaneous and bone infectious disease caused by multidrug resistant bacteria.
[Show abstract][Hide abstract] ABSTRACT: In this study, we compared different methods of colistin susceptibility testing, disc diffusion, agar dilution and Etest using a set of Enterobacteriaceae isolates that included colistin-resistant strains.
Susceptibility of 200 clinical isolates of Enterobacteriaceae to colistin was tested to compare agar dilution (reference method), disc diffusion (50 and 10 μg) and Etest. MICs (minimum inhibitory concentrations) were interpreted using the criteria established by the European Committee on Antimicrobial Susceptibility Testing (EUCAST). Colistin exhibited excellent activity against Escherichia coli and E. cloacae (MIC90 = 0·5 mg l(-1)). In contrast, colistin was less active against Klebsiella pneumoniae (MIC90 = 16 mg l(-1)). Resistance rates varied from 0% in E. coli to 1·8% in E. cloacae and 13% in K. pneumoniae. High rates of very major errors were observed in the disc diffusion test using either the criteria of the Comité de l'antibiogramme de la Société Française de Microbiologie (CA-SFM) or the criteria of the Clinical and Laboratory Standards Institute (CLSI), respectively, 3·5 and 2·5%. When the criteria of Gales et al. were applied, the number of very major errors was reduced to one (0·5%). The Etest showed good concordance with agar dilution method.
Disc susceptibility testing methods are unreliable on detecting colistin resistance. MIC should be determined to confirm the susceptibility results by disc diffusion.
We recommend the determination of MIC by Etest for all multidrug-resistant Enterobacteriaceae when colistin is required for the treatment.
Letters in Applied Microbiology 09/2011; 53(5):546-51. · 1.63 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: Medication noncompliance is one of the daily problems of the physician. Improving the medication adherence allows better management of hypertension. The aim of this work was to determine the level of compliance for patients with hypertension and to identify factors that determine compliance.
A cross-sectional study was carried out among a sample of hypertensive patients attending general and specialist practitioners in public or private clinics of Sfax. Two hundred and seventy-three participants had accepted to be interviewed. Patients were identified as noncompliants using a questionnaire developed by the Comité de lutte contre l'hypertension artérielle (CFLHTA).
Non-compliance rate was 63.4%. The low level of education was associated with a lower adherence. The monotherapy, the once-daily regimen with fewer number of tablets were associated with a better adherence (p<10(-6)). The welcome and the availability of drugs in the public clinic affect positively the adherence of patients (p<0.0002). A patient very satisfied with his consultation and the explanation given by the doctor about his illness and its treatment had a better adherence (p<0.00003).
Our study had demonstrated a low compliance with antihypertensive drug therapy. Tunisian health care system should elaborate a management plan which takes into account our particular predictors of compliance to improve adherence to antihypertensive medication.
Annales de cardiologie et d'angeiologie 06/2010; 59(3):131-7. · 0.21 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: The authors studied the epidemiology of pharyngitis in children and evaluated the contribution of a rapid streptococcal test.
This prospective study was conducted from June 2007 to May 2008 in a primary health care institution (Policlinique de la Caisse Nationale de Sécurité Sociale) in Tunisia. Clinical findings were recorded; throat swabs were performed, and a rapid streptococcal test was made.
Five hundred and four children were included in this study. The mean age was 5 years and 8 months. Culture was positive for group A streptococcus in 166 cases (32.9 %). Group A streptococcus was more frequently isolated in children aged 5 to 8 years. There was no difference in clinical features between groups of streptococcal and non-streptococcal pharyngitis. The sensitivity and specificity of the rapid test were respectively 93.2 and 95.3 %.
Pharyngitis was of bacterial origin in one third of cases; among these, group A streptococcus was the most frequent bacterium. The rapid test is a quick and reliable tool for the diagnosis of pharyngitis and hence an appropriate treatment.
[Show abstract][Hide abstract] ABSTRACT: 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.
All bacteriologically confirmed cases of community-acquired meningitis were recorded between 1993 and 2001.
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.
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.
[Show abstract][Hide abstract] ABSTRACT: 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 β-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.
Medecine Et Maladies Infectieuses - MED MAL INFEC. 01/2006; 36(2):105-110.
[Show abstract][Hide abstract] ABSTRACT: To investigate the fate of Aeromonas hydrophila pathogenicity when cells switch, in nutrient-poor filtered sterilized seawater, between the culturable and nonculturable state.
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.
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.
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.
Journal of Applied Microbiology 02/2004; 97(3):557-65. · 2.20 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: To characterize hypochlorous acid (HOCl) stress resistance of Staphylococcus aureus and to assess physiological state and changes in cell morphology.
Clinical wild-type strain of S. aureus was used in the stress with HOCl at concentrations ranging from 0 to 4 mg l(-1). Concentrations below 1.5 mg l(-1) caused no significant drop in viability. During 2 h of HOCl stress at 2 mg l(-1), there was appearance of minicells capable of passing through the 0.45 microm pores of filtration membranes. Intracellular proteins increased gradually to reach a level of 51% of dry weight and an enhanced synthesis of at least two proteins of 23 and 220 kDa was concluded.
Staphylococcus aureus can undergo morphological and physiological changes during 2 h of exposure to 2 mg l(-1) of HOCl, which represents an adaptative response towards the hypochlorous acid stress. This evolution limits the use of 0.45 microm pores size membrane filters for research on S. aureus in waters and the clinical environment.
Letters in Applied Microbiology 02/2004; 38(3):245-50. · 1.63 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: SUMMARY Bacteriological analyse of surface water in an urban effluent and in coastal marine environment showed a seasonal contamination of this water by motile Aeromonas. Spatial and seasonal changes of Aeromonas abundances were studied, in relation to several environmental factors, in the purified effluent and in seawater. The motile Aeromonas spp. and the fecal coliform distributions in the sewage treatment effluent showed the same seasonal cycles with a maximum occu- ring in winter (mean: 29-106 UFC/100 ml) and a minimum in summer (mean of 640* UFC/100 mL). The abatement of Aeromonas abundances was corre- lated with a strong irradiation and a low turbidity. In the coastal marine water, there was an inversion of the motile Aeromonas spp. cycle in comparison with that of fecal coliforms, with high levels in hot periods (mean: 56 CFU/100 mL for S3) and low levels in cold periods (mean of 5 CFU/100 mL for S3). Salinity appeared responsible for the déstabilisa tion of the seasonal séquences of Aeromonas and their réduction with non détectable concentrations in water analysed volumes. The présence of thèse bacteria in the purified effluent, sometimes with concentrations higher than those of the fecal coliforms, poses a problem of health hazard and clearly show that fecal contamination bacteria cannot be prédictive for the présence or the absence of Aeromonas and, consequently, cannot be considered as good indicators of pollution.