Sana Kammoun

Prosthetic valve endocarditis: management strategies and prognosis: A ten-year analysis in a tertiary care centre in Tunisia.

Background Prosthetic valve endocarditis (PVE) is a rare and serious complication after heart valve replacement; its optimal management strategy, though, still needs to be defined.Objective To study the clinical, microbiological and echocardiographic characteristics of PVE and to analyse the influence of the adopted therapeutic strategy (medical or surgical) on short- and midterm outcome in a tertiary care centre in a developing country (Tunisia).Methods All cases of PVE treated in our institution between 1997 and 2006 were retrospectively analysed according to the modified DUKE criteria.Results A total of 48 PVE episodes were diagnosed (30 men and 18 women), mean age was 37.93 years. Twenty-eight patients (58.33%) were exclusively medically treated, whereas 20 (41.66%) were treated by a combined surgical and medical strategy. Indications for surgery were haemodynamic deterioration in eight patients (40%), annular abscess in six (30%) and persisting sepsis in six (30%). In comparison with those from the medical group, operated patients had a longer delay to diagnosis (p=0.025), were more frequently in heart failure (p=0.04) and experienced more early complications (p=0.011); they also more frequently had prosthetic dehiscence (p=0.015), annular abscesses (p=0.039) and vegetations >10 mm (p=0.008). Conversely, no differences were found between the groups in terms of age, sex, or nature of involved organisms. In-hospital mortality for the medical group was 14.28% and for the surgical group 35% (p=0.09).Conclusion PVE is a very serious condition carrying high mortality rates regardless of the adopted strategy. Our study demonstrates that, in selected patients, medical treatment could be a successful and acceptable approach. (Neth Heart J 2009;17: 56-60.)

Evaluation of molecular detection of extrapulmonary tuberculosis and resistance to rifampicin with GeneXpert® MTB/RIF

OBJECTIVE We aimed to evaluate the GeneXpert® MTB/RIF test for the diagnosis of extrapulmonary tuberculosis. The test simultaneously detects Mycobacterium tuberculosis complex and resistance to rifampicin. METHODS We analyzed 153 clinical samples collected in a tertiary hospital in Sfax, Tunisia, between 2013 and 2014. We performed the GeneXpert® test, a Ziehl-Neelsen and auramine-rhodamine staining, conventional culture on MGIT 960 and LJ media, and we tested the resistance to anti-tuberculosis drugs on MGIT 960 and LJ media for each sample. Diagnosis was based on clinical, radiological, microbiological, pathological, and therapeutic data. RESULTS We considered that 59 patients out of 153 presented with tuberculosis. PCR was positive in 50 samples and all of these samples were susceptible to rifampicin. Sensitivity, specificity, positive predictive value, and negative predictive value of the GeneXpert® test were 84.7%, 96.8%, 94.3%, and 91%, respectively, compared with diagnosis. We observed a statistically significant difference between the direct test and the GeneXpert® test, and between culture and the GeneXpert® test. No statistically significant difference was observed between pathological results and the GeneXpert® test. Sensitivity of the GeneXpert® test was 87.5% in biopsies, 80% in pus and abscesses, and 66.7% in biological fluids. All strains were susceptible to rifampicin with culture and GeneXpert® test. CONCLUSION The GeneXpert® test helped detect a higher proportion of M. tuberculosis complex. It does not replace conventional diagnostic methods but it is a useful addition to achieve better sensitivity and obtain rapid results.

Drug susceptibility testing of Mycobacterium tuberculosis by a nitrate reductase assay applied directly on microscopy-positive sputum samples

AIMS AND OBJECTIVES Current methods for drug susceptibility testing (DST) of Mycobacterium tuberculosis (MTB) are either costly or slow. As the prevalence of multidrug-resistant (MDR) strains increases, the need for fast, reliable, and inexpensive methods is obvious. This study evaluated a rapid colorimetric nitrate reductase assay (NRA) for direct DST of MTB directly from clinical sputum samples. METHODS A total of 111 sputa with positive microscopy results for acid-fast bacilli (AFB) with more than 10 AFB per high-power field were used in the study. The samples were decontaminated using the modified Petroff method. The NRA results were compared with the reference indirect proportion method. RESULTS The sensitivity and the specificity of the direct NRA were 90% and 97.3%, 92.6% and 98.2%, 52.9% and 100%, and 28.6% and 100% for rifampin, isoniazid, streptomycin, and ethambutol, respectively. The results were in most cases available in 28days (84.3%). CONCLUSIONS The direct NRA could be used as a rapid, inexpensive, and accurate method to determine rifampin and isoniazid susceptibility directly from sputum. The technique might become a valid alternative to traditional methods, especially in low-income countries.

First-time detection and identification of the Mycobacterium tuberculosis Complex members in extrapulmonary tuberculosis clinical samples in south Tunisia by a single tube tetraplex real-time PCR assay

Introduction Tunisia has one of the highest burdens of extrapulmonary tuberculosis (EPTB) among tuberculosis (TB) cases but the contribution of MTBC-mediated human EPTB is unknown. EPTB diagnosis is challenging due to the paucibacillary nature of clinical samples. Therefore, a need of a simplified molecular method for sensitive and specific TB detection and differentiation of MTBC members caused EPTB remains a priority to an early diagnosis, optimize successful anti-TB treatment and minimize transmission. We evaluated the performance of a single tube tetraplex Taq Man real time PCR for EPTB detection and differentiation between MTBC members directly on extrapulmonary samples. Materials and methods Extrapulmonary samples obtained from clinically suspected EPTB patients from 2013 to April 2015 were tested by Ziehl Neelsen Staining, mycobacterial culture and qPCR assay for RD1, RD9, RD12 and ext-RD9 targets (MTBC-RD qPCR). The performance of qPCR was compared to a reference standard based on MTBC culture and/or at least two criteria of a composite reference standard (CRS) including clinical, radiological, histopathological and therapeutic findings. Results EPTB was identified in 157/170 (92.4%) of included patients of whom 99 (63%) were confirmed by culture and 58 (36.9%) by CRS criteria. The sensitivity and specificity of qPCR, in comparison to the reference standard were 100% (157/157) and 92.3% (12/13), respectively. The sensitivity of qPCR was statistically significant as compared to culture and smear microscopy (P< 0.001). QPCR results showed M. bovis identification in 77.1% of extrapulmonary samples in occurrence to lymphadenitis infection. M. tuberculosis and M.bovis BCG were detected in 21.6% and 1.3% of cases, respectively. Conclusions MTBC–RD qPCR proved to be a rapid and sensitive assay for simultaneously TB detection and MTBC members identification on extrapulmonary samples within 1.5 days after sample receipt. Its high sensitivity could make this method a useful tool in diagnosing TB in addition to routine conventional methods and TB clinical parameters.

Les modifications électrocardiographiques au cours de la fièvre boutonneuse méditerranéenne

Summary Mediterranean spotted fever is an eruptive disease caused by Rickettsia conorii . Endothelitis comes as a consequence of this infection. In this work we studied the electrocardiographic change of 9 patients with mediterranean spotted fever. Six had alteration of cardiac conduction. The pathogenic mechanism of vascular injury induced myocardial oedema. All patients with mediterranean spotted fever should be screened with an ECG.

Molecular characterization of Mycobacterium tuberculosis strains resistant to isoniazid

Objective/background: Tuberculosis is a major public health problem and the emergence of drug resistance complicates the situation even more. It is therefore crucial to implement all conclusions from the studies that aim at a better understanding of the molecular mechanisms which govern the emergence and the evolution of drug resistance. The aim of this study is to assess the degree of involvement of the inhA and katG genes in the acquisition of isoniazid resistance in clinical strains of Mycobacterium tuberculosis. Methods: The inhA and katG genes were sequenced in 21 strains of M. tuberculosis with different resistance profiles and from different regions. Results: Analysis of the sequences obtained by comparison to those of the reference strain H37Rv showed that 95.2% had mutations. KatG S315T was the most common mutation (85.7%). The mutation katG T275A was revealed in two strains (9.5%). Two different point mutations in the inhA gene and its promoter region were identified as C-15T and G56A at a frequency equal to 14% and 10%, respectively. The G56A mutation is a new silent mutation. Our study showed no correlation between found mutations and multidrug resistance. Among the 21 strains studied, only one strain showed no mutations. Conclusion: In terms of this study, we characterized the mutations involved in resistance to isoniazid. katG S315T was by far the most frequent mutation, followed by C-15T. The frequency of these mutations was concordant with those reported in literature including those in intermediate tuberculosis endemic countries.

Evaluation of the BACTEC MGIT 960 TB with Solid Media for Recovery of Mycobacteria from Extrapulmonary Specimens in South Tunisia

The slow growth of M. tuberculosis complex is a major challenge for TB diagnosis, hence the importance of using media to obtain quick results. We compared the system MGIT960 to solid media: LJ and Coletsos in the diagnosis of extrapulmonary tuberculosis. A total of 634 extrapulmonary samples were processed for direct AFB smear examination, and culture on MGIT960 and solid media. 98 strains were isolated by the three media (15.4%). The mycobacterial recovery rate was 93.8%, 77.5% and 70.4% respectively for MGIT960, LJ and Coletsos media. The mean turnaround time for mycobacterial growth for MGIT960 was 18.5 ± 7.6 days. It was respectively 44.8 ± 19.3 and 42.8 ± 19 days for LJ and Coletsos media. Unlike most studies, the MGIT960 contamination rate (1.7%) was lower than that of solid media (2.2% for LJ and 2.5% for Coletsos). The MGIT 960 offers several advantages: speed, sensitivity and ease of use.

Screening and Detecting Salmonella in Different Food Matrices in Southern Tunisia Using a Combined Enrichment/Real-Time PCR Method: Correlation with Conventional Culture Method

A combined enrichment/ newly developed invA TaqMan® real-time PCR (qPCR) method as a screening assay to detect Salmonella spp. in 500 naturally food matrices is evaluated. DNA template for qPCR was extracted from an overnight pre-enriched sample in buffered peptone water using lysis–guanidine isothiocyanate method. Heterologous internal amplification control (IAC) was incorporated during qPCR assays and co-amplified with the invA gene of the target pathogen. InvA qPCR exhibited 100% specificity when testing 94 Salmonella strains (inclusivity) and 32 non-Salmonella strains (exclusivity). The qPCR showed a consistent detection of two copies of the invA gene/PCR reaction, a good intra- and inter-run reproducibility with a good PCR efficiency (89.6%). QPCR was sensitive and showed Salmonella detection at 8.5 × 100 CFU mL-1 of artificially spiked poultry meat -BWP solution in less than 40 cycles. When analyzing 500 different food matrices and comparing the results with the ISO 6579:2002 conventional culture method, the sensitivity and specificity were 100 and 76.6%, respectively. QPCR showed Salmonella spp. DNA in raw poultry meat 27/45 (60%), milk 31/93 (33.3%), raw red meat 5/13 (38.5%), and fish 11/46 (23.9%) samples. The prevalence of Salmonella spp. in cakes, dairy, cooked meals, charcuterie products using qPCR was 11/14 (26.8%), 5/22 (22.7%), 32/150 (21.3%), and 5/20 (25%), respectively, compared to 0% as demonstrated by culture. S. Anatum was the most common serovar found associated with red meat compared to S. kentucky isolated from fish and poultry meat. In conclusion, our study is the first to use a combined enrichment/invA qPCR method as a screening assay to detect Salmonella DNA in different types of commercialized food in Southern Tunisia. QPCR results indicate that Salmonella contamination is common in milk and in other types of food samples.

Evaluation of GeneXpert MTB/RIF for the detection of Mycobacterium tuberculosis and resistance to rifampin in extra-pulmonary specimens

Abstract Aims and objectives This study evaluated the performance of GeneXpert (GX) for direct detection of MTB in extra-pulmonary specimens and assessed the ability of the assay to detect resistance to RIF. Methods 104 clinical samples from a tertiary hospital in Sfax, Tunisia were analyzed. Specimens were processed using GX, Ziehl Neelsen and auramine smear, conventional culture on LJ and MGIT 960 media, and drug phenotypic susceptibility testing on LJ and MGIT 960. The diagnosis was made based on clinical, radiological, microbiological, pathological and therapeutic criteria. Results In total, 51 patients were considered tuberculous. The PCR result obtained in less than two hours was positive for 46 samples and rifampicin was sensitive to all these cases. The sensitivity, specificity, positive predictive value and negative predictive value of GX were 90%, 60.6%, 19.6% and 98.3% compared with direct examination, 84.8%, 74.6%, 60.9% and 91.4% compared with culture and 84.3%, 94.3%, 93.4%, 86.2% compared with final diagnosis. The sensitivity of the GXt was 86% in biopsies and 75% in pus, collections and in biological fluids. Conclusion The GX is a simple, rapid technique for real-time PCR and has increased the sensitivity of detection of Mycobacterium tuberculosis complex. It must be part of the diagnostic arsenal of tuberculosis without replacing conventional microbiological tools and allow early diagnosis and appropriate treatment.

S-02: Endocardite à Coxiella burnetii : à propos de 10 cas

Introduction – objectifs Les endocardites a Coxiella burnetii representent 1 a 5 % des endocardites infectieuses. Elles posent des difficultes sur le plan diagnostique et therapeutique. L’objectif de notre etude etait de preciser les particularites epidemiologiques, cliniques et therapeutiques de ces endocardites. Materiels et methodes Etude retrospective realisee dans les services de Cardiologie et des Maladies Infectieuses entre 2005 et 2013. Tous les patients avaient une endocardite certaine a C. burnetii selon les criteres diagnostiques de Duke modifies. Resultats Notre etude avait inclus 10 cas d’âge moyen de 44 [17–70] ans. Quatre cas avaient une exposition professionnelle evidente. Trois cas avaient une prothese valvulaire et quatre cas avaient une cardiopathie congenitale. Le delai moyen de diagnostic etait de 5 mois. Le tableau clinico-biologique comportait une fievre (6 cas), asthenie (4 cas), insuffisance cardiaque (2 cas), anemie (7 cas) et/ou thrombopenie (4 cas). Les hemocultures etaient negatives dans 9 cas. Une echographie etait contributive dans 7 cas (7 vegetations et 2 abces peri-annulaires). Six cas etaient traites par une association de doxycycline et hydroxychloroquine. Un remplacement valvulaire a ete pratique chez 5 cas. La PCR etait realisee sur 3 valves avec mise en evidence de C. burnetii dans tous les cas. Trois patients sont decedes suite a des complications thrombo-emboliques. Conclusion L’endocardite infectieuse a C. burnetii est une pathologie grave et peu etudiee. Sa frequence reelle reste sous-estimee a cause de la difficulte du diagnostic positif. Elle doit etre evoquee systematiquement devant toute suspicion d’endocardite infectieuse a hemoculture negative sur terrain predispose.