The Role of Platelets in Infective Endocarditis

Over the last decade, the incidence of infective endocarditis (IE) has increased, with a change in the frequency of causative bacteria. Early evidence has substantially demonstrated the crucial role of bacterial interaction with human platelets, with no clear mechanistic characterization in the pathogenesis of IE. The pathogenesis of endocarditis is so complex and atypical that it is still unclear how and why certain bacterial species will induce the formation of vegetation. In this review, we will analyze the key role of platelets in the physiopathology of endocarditis and in the formation of vegetation, depending on the bacterial species. We provide a comprehensive outline of the involvement of platelets in the host immune response, investigate the latest developments in platelet therapy, and discuss prospective research avenues for solving the mechanistic enigma of bacteria-platelet interaction for preventive and curative medicine.

Platelets and Escherichia coli: A Complex Interaction

Apart from their involvement in hemostasis, platelets have been recognized for their contribution to inflammation and defense against microbial agents. The interaction between platelets and bacteria has been well studied in the model of Staphylococcus and Streptococcus but little described in Gram-negative bacteria, especially Escherichia coli. Being involved in the hemolytic uremic syndrome as well as sepsis, it is important to study the mechanisms of interaction between platelets and E. coli. Results of the published studies are heterogeneous. It appears that some strains interact with platelets through the toll-like receptor-4 (TLR-4) and others through the Fc gamma glycoprotein. E. coli mainly uses lipopolysaccharide (LPS) to activate platelets and cause the release of antibacterial molecules, but this is not the case for all strains. In this review, we describe the different mechanisms developed in previous studies, focusing on this heterogeneity of responses that may depend on several factors; mainly, the strain studied, the structure of the LPS and the platelet form used in the studies. We can hypothesize that the structure of O-antigen and an eventual resistance to antibiotics might explain this difference.

A Massive Number of Extracellular Tropheryma whipplei in Infective Endocarditis: A Case Report and Literature Review

Whipple’s disease (WD) is a chronic multisystemic infection caused by Tropheryma whipplei. If this bacterium presents an intracellular localization, associated with rare diseases and without pathognomonic signs, it is often subject to a misunderstanding of its physiopathology, often a misdiagnosis or simply an oversight. Here, we report the case of a patient treated for presumed rheumatoid arthritis. Recently, this patient presented to the hospital with infectious endocarditis. After surgery and histological analysis, we discovered the presence of T. whipplei. Electron microscopy allowed us to discover an atypical bacterial organization with a very large number of bacteria present in the extracellular medium in vegetation and valvular tissue. This atypical presentation we report here might be explained by the anti-inflammatory treatment administrated for our patient’s initial diagnosis of rheumatoid arthritis.

The Antibacterial Effect of Platelets on Escherichia coli Strains

Platelets play an important role in defense against pathogens; however, the interaction between Escherichia coli and platelets has not been well described and detailed. Our goal was to study the interaction between platelets and selected strains of E. coli in order to evaluate the antibacterial effect of platelets and to assess bacterial effects on platelet activation. Washed platelets and supernatants of pre-activated platelets were incubated with five clinical colistin-resistant and five laboratory colistin-sensitive strains of E. coli in order to study bacterial growth. Platelet activation was measured with flow cytometry by evaluating CD62P expression. To identify the difference in strain behavior toward platelets, a pangenome analysis using Roary and O-antigen serotyping was carried out. Both whole platelets and the supernatant of activated platelets inhibited growth of three laboratory colistin-sensitive strains. In contrast, platelets promoted growth of the other strains. There was a negative correlation between platelet activation and bacterial growth. The Roary results showed no logical clustering to explain the mechanism of platelet resistance. The diversity of the responses might be due to strains of different types of O-antigen. Our results show a bidirectional interaction between platelets and E. coli whose expression is dependent on the bacterial strain involved.

A Novel Approach for Detecting Unique Variations among Infectious Bacterial Species in Endocarditic Cardiac Valve Vegetation

Infectious endocarditis (IE) remains one of the deadliest heart diseases with a high death rate, generally following thrombo-embolic events. Today, therapy is based on surgery and antibiotic therapy. When thromboembolic complications in IE patients persist, this is often due to our lack of knowledge regarding the pathophysiological development and organization of cells in the vegetation, most notably the primordial role of platelets and further triggered hemostasis, which is related to the diversity of infectious microorganisms involved. Our objective was to study the organization of IE vegetations due to different bacteria species in order to understand the related pathophysiological mechanism of vegetation development. We present an approach for ultrastructural analysis of whole-infected heart valve tissue based on scanning electron microscopy and energy-dispersive X-ray spectroscopy. Our approach allowed us to detect differences in cell organization between the analyzed vegetations and revealed a distinct chemical feature in viridans Streptococci ones. Our results illustrate the benefits that such an approach may bring for guiding therapy, considering the germ involved for each IE patient.

Ultrastructure of a late-stage bacterial endocarditis valve vegetation

Infective endocarditis (IE) remains a severe illness with high mortality rate, despite advances in antibiotic therapy and cardiac surgery. If infectious bacteria and platelets are two key players of human IE vegetation developmental process, their interactions and respective roles in fully developed late-stage IE vegetations remain obscure. The objective of this study was to better understand the organization of the different components of the IE vegetation and to provide a detailed description of this vegetation ultrastructure. A late stage Staphylococcal endocarditic vegetation was provided from a 13 years teenager patient. After reception of the surgical piece, we carried out a histological study using routine methods, notably the hematoxylin-eosin-saffron staining. Labeling with the anti-CD 61 antibody was also carried out. In a second step, we used transmission electron microscopy to describe the different regions making up the vegetation. Our ultrastructural study revealed vegetation was clearly composed by three different regions and identified the specific location of the bacteria and platelets in the vegetation tissues. Histological analysis showed that platelets and Staphylococcus aureus were not co-localized. Electron microscopy study confirmed that S. aureus were found at distance from platelets, as well from immune cells, embedded in a biofilm and/or a necrotic area. These results reveal a development of a deep bacteria-only niche in vegetation, raising questions about medication access to these microorganisms. Vegetation composed of three regions: a region rich in bacteria incorporated into the necrotic tissue, the second region composed of fibrin filaments and the third region rich in platelets and free of bacteria.

Statins potentiate the antibacterial effect of platelets on Staphylococcus aureus

Platelets have largely demonstrated their implication in anti-infectious immunity. This effect is ensured by the secreted molecules stored mostly in platelet alpha granules. Previous studies have reported that Staphylococcus aureus showed sensitivity to this antibacterial effect of platelets. Statins, for their part, have shown a modulating effect on platelet activation. Furthermore, several studies have reported a protective effect of statins in staphylococcal endocarditis. The aim of this study was to investigate the influence of statins on the antibacterial effect of washed platelets. Blood samples were collected from healthy donors (n = 35). PRP was prepared according to the ISTH recommendation. Bacteria were incubated for four hours with untreated-washed platelets, or rather treated by statins and/or GPIIbIIIa antagonists. In order to evaluate the antibacterial effect, the platelet-bacteria mix was spread on the blood agar to count the number of colonies after 18 hours of incubation. Measurement of CD 41 and CD62P expression by flow cytometry was performed to evaluate the effect of statin on bacterial-induced platelet activation. Statins have shown a potentiation of the antibacterial effect of washed platelets (p < .01 for Atorvastatin and Rosuvastatin and p < .001 for Fluvastatin vs untreated washed platelets condition). This effect of statins was dose-dependent and was more significant at 20 μM. The addition of Fluvastatin to platelet-bacterial mix significantly increased the expression of platelet CD41 and CD62P (p < .05 and p < .01 vs resting washed platelets, respectively). Tirofiban, GPIIbIIIa antagonist, reversed the antibacterial effect of washed platelets and suppressed the potentiating effect of statins. Our study demonstrated that statins potentiate the anti-staphylococcal effect of washed platelets. This result may explain the beneficial effect of statins on Staphylococcus aureus infective endocarditis. Further studies are therefore required to explain this effect at the molecular level and to assess its impact in vivo.

Antiplatelet Agents Have a Distinct Efficacy on Platelet Aggregation Induced by Infectious Bacteria

Platelets are the cornerstone of hemostasis. However, their exaggerated aggregation induces deleterious consequences. In several diseases, such as infectious endocarditis and sepsis, the interaction between platelets and bacteria leads to platelet aggregation. Despite platelet involvement, no antiplatelet therapy is currently recommended in these infectious diseases. We aimed here, to evaluate, in vitro, the effect of antiplatelet drugs on platelet aggregation induced by two of the bacterial pathogens most involved in infectious endocarditis, Staphylococcus aureus and Streptococcus sanguinis. Blood samples were collected from healthy donors (n = 43). Treated platelet rich plasmas were incubated with three bacterial strains of each species tested. Platelet aggregation was evaluated by Light Transmission Aggregometry. CD62P surface exposure was evaluated by flow cytometry. Aggregate organizations were analyzed by scanning electron microscopy. All the strains tested induced a strong platelet aggregation. Antiplatelet drugs showed distinct effects depending on the bacterial species involved with different magnitude between strains of the same species. Ticagrelor exhibited the highest inhibitory effect on platelet activation (p <0.001) and aggregation (p <0.01) induced by S. aureus. In the case of S. sanguinis, platelet activation and aggregation were better inhibited using the combination of both aspirin and ticagrelor (p <0.05 and p <0.001 respectively). Aggregates ultrastructure and effect of antiplatelet drugs observed by scanning electron microscopy depended on the species involved. Our results highlighted that the effect of antiplatelet drugs depended on the bacterial species involved. We might recommend therefore to consider the germ involved before introduction of an optimal antiplatelet therapy.

The distinct effects of aspirin on platelet aggregation induced by infectious bacteria

Bacteria induce platelet aggregation triggered by several mechanisms. The goal of this work was to characterize platelet aggregates induced by different bacterial strains and to quantify the effect of aspirin treatment using aggregation tests, as well as a novel approach based on confocal analysis. Blood samples were obtained from either healthy donors (n = 27) or patients treated with long-term aspirin (n = 15). The bacterial species included were Staphylococcus aureus, Enterococcus faecalis, and Streptococcus sanguinis. The different aggregate's ultrastructures depending on the bacterial strain were analyzed using Scanning electron microscopy. Quantification of the size of the platelet aggregates, their mean number as well as the bacterial impregnation within the aggregates was performed using confocal laser scanning light microscopy. Light Transmission Aggregometry was also performed. Our results reported distinct characteristics of platelet aggregates depending on the bacterial strain. Using confocal analysis, we have shown that aspirin significantly reduced platelet aggregation induced by S. aureus (p = .003) and E. faecalis (p = .006) with no effect in the case of S. sanguinis (p = .529). The results of the aggregometry were concordant with those of the confocal technique in the case of S. aureus and S. sanguinis. Interestingly, aggregation induced by E. faecalis was detected only with confocal analysis. In conclusion, our confocal scanning microscopy allowed a detailed study of the platelet aggregation induced by bacteria. We showed that aspirin acts on bacterial-induced platelet aggregation depending on the species. These results are in favor of the use of aspirin considering the species and the bacterial strain involved.

Prevalence and risk factors of hepatitis B in Tunisia

Background

Hepatitis B virus (HBV) infection is a major public health problem. Data related to epidemiology, distributions and outcomes of VHB infections in Tunisia remains scarce. This work aimed to study the prevalence of HBV infections and their distribution as well as the main risk factors associated to HBV infection.

Methods

Our study was a cross-sectional household- based study carried out among a representative sample of 22 275 from January 2014 to December 2015. Sampling was based on the National Census of 2014. For data collection, questionnaires were administrated by trained investigator and blood samples were sent to the Reference laboratory for analysis of HBV markers.

Results

Among 21720 surveyed subjects, 19663 subjects had a laboratory tests and the serological results reached to 19155. Overall prevalence of HBs Ag was 1.7% [1.6-1.9]. Prevalence of HBsAg was significantly higher in men (2.1% against 1.4%; p &lt; 10-3), in age group more than 20 years (2.1% against 0.1% p ≪10-3) and in the Central region (2.3%; p &lt; 10-3). Among the associated risk factors in univariate analysis were chronic dialysis, dental care, surgical intervention, hospitalization, traditional circumcision, scarification and multiple sexual partners. Multivariate analysis showed that male gender, age over 20 years, center and south regions, hospital follow-up of a chronic pathology and having a family member chronic carrier of HBs Ag were the associated risk factors of HBV infection and vaccination was the only protective factor.

Conclusions

Our study allowed to have a clear estimate of the national prevalence of HBsAg and to classify Tunisia as a country of low endemicity of Hepatitis B. This decline is mainly due to the introduction of vaccination since 1995 and the improvement of the health system. However, more efforts should be paid to reduce nosocomial transmission and traditional high-risk behaviors.

Key messages

Tunisia has become a country of low endemicity for hepatitis B. This was a result to the introduction of vaccination since 1995.

Impact of hepatitis B vaccine in Tunisia 20 years after its introduction

Introduction

Vaccination against hepatitis B represents the most effective preventive measure to reduce the global impact of this infection. In Tunisia hepatitis B vaccination was introduced for health professionals in 1992 and for the general population in 1995. The objectives of this study were to evaluate the impact of vaccination twenty years after its introduction.

Methods

It was a descriptive study of data provided by the national survey of prevalence of Hepatitis B in Tunisia, which was a household-based study conducted in 2015. Blood samples sent to the reference laboratory to test markers of hepatitis B virus infection. The Vaccine effectiveness rate was calculated using the following formula: VE = 1 - Odds-ratio (OR), where OR = ratio of odds of being vaccinated among subjects with positive HBsAg test results to the odds of being vaccinated among subjects with negative HBsAg test results.

Results

Approximately a quarter of our population reported having been vaccinated against HBV, a coverage rate of 26.9%. Among subjects above 20 years of age, this rate was 85.3%. Besides, 83.7% of vaccinated subjects had received the three required doses of the HBV vaccine. Analysis of vaccination status by great regions of the country showed that the vaccination coverage rate was higher in the southern region. Regarding HBsAg prevalence, the rate was significantly higher among unvaccinated subjects 0.3% vs 2.2% in those vaccinated (OR = 0.11 [0.07-0.18]). We found that among vaccinated subjects, the serologic response rate at vaccination was only 63.2% which represented 16.2% of the total population. The vaccine effectiveness indicated that vaccination reduced by 88.6% the risk of HBV infection.

Conclusions

These results demonstrate that vaccination against hepatitis B introduced in the national immunization schedule since 1995 has reduced the infection although the vaccination coverage rate remains below 90%.

Key messages

Importance of vaccination that reduced by 88.6% the risk of HBV infection. More effort required to raise awareness about vaccination against HBV.

Aspirin Effect on Staphylococcus aureus-Platelet Interactions During Infectious Endocarditis

Infectious endocarditis (IE) is a rare disease associated with high mortality and morbidity rate. The platelet–bacterial interaction presents the cornerstone of the development of endocardial vegetation. The epidemiology of IE has undergone profound changes between the last and the new decade, with Staphylococcus aureus becoming the main incriminated species. Despite improvements in antibiotic and surgical therapies, embolic disorders remain highly associated with IE that can be fatal. Antiplatelet drugs have been widely proposed to overcome embolic events associated with IE. This proposal has been supported by numerous in vitro, experimental, and clinical studies. However, other studies have yielded conflicting results. In this review, we focus on the effect of aspirin on the genesis of S. aureus endocarditic vegetation, as well as on the management of embolic and hemorrhagic events related to it, starting by its influence on the platelet–bacteria interaction.

Increased levels of soluble HLA-G molecules in Tunisian patients with chronic hepatitis B infection

Hepatitis B virus (HBV) infection is a global health problem. The mechanisms of immune tolerance in HBV infection are still unclear. The host immune response plays a critical role in determining the outcome of HBV infection. Human leucocyte antigen-G (HLA-G) is involved in immunotolerogenic process and infectious diseases. This study aimed to explore the implication of soluble HLA-G (sHLA-G) and its isoforms in HBV infection. Total sHLA-G (including shedding HLA-G1 and HLA-G5) was analysed by ELISA in 95 chronic HBV patients, 83 spontaneously resolvers and 100 healthy controls (HC). To explore the presence of sHLA-G dimers, we performed an immunoprecipitation and a Western blot analysis on positive samples for sHLA-G in ELISA. The serum levels of sHLA-G were significantly increased in patients with chronic HBV patients compared to spontaneously resolvers and HC (P<.0001). Interestingly, we found an increased level of sHLA-G1 in chronic HBV patients than in spontaneously resolvers and HC (P<.001). In addition, the expression of HLA-G5 seems to be higher in the sera of chronic HBV patients than spontaneously resolvers (P=.026). The analysis of HLA-G dimers showed the presence of homodimers in 93% of chronic HBV patients, 67% in spontaneously resolvers and 60% in HC. These results provide evidence that sHLA-G may have a crucial role in the outcome of HBV infection and could be proposed as a biomarker for infection outcome. Based on its tolerogenic function, HLA-G might be considered as a new promising immunotherapeutic approach to treat the chronic infection with HBV.

[Seroprevalence of human parvovirus B19 in children with fever and rash in the North of Tunisia]

The aim of the study is to evaluate the prevalence of specific antibodies anti-human parvovirus B19 (PVB19) immunoglobulin M (IgM) and IgG in children with fever and rash. This study involved 257 children aged from 7 months to 15 years with febrile rash unrelated to measles and rubella (seronegative for IgM). The sera were examined by immunoenzymatic assay. Detection of antibodies of PVB19 was done by enzyme-linked immunosorbent assay (Elisa). In our study, prevalence of immunoglobulin G (IgG) and IgM were 44 and 11.3%, respectively. Clinically, children with positive IgM serology had submitted an erythema infectiosum (13/29 cases), myocarditis (1 case), encephalitis (1 case), severe sickle cell anemia (7 cases), and immunocompromised (7 cases). The incidence rate of viral infection was 11.3%; most of the cases of PVB19 infection occurred between the months of May and August. Incidence was higher in the 10-15 years age group (21%). The prevalence of IgG antibody varied and increased with age, it rises from 38.2% in preschool children (19 months-4 years) to 53.5% in those aged between 4.5 and 15 years, reaching 58% in the 10-15 years age group. The four risk factors of PVB19 infection are: (1) those aged between 4.5 and 9 years, which is the most affected age group (P = 0.0018); (2) female gender in children aged between 19 months and 4 years (P = 0.037); (3) transfusion and (4) immune deficiency (P = 0.022 and P = 0.001, respectively). The study of the prevalence of PVB19 infection shows that viral infection is acquired early in childhood, increases with age; viral transmission is favored by the community life. Because of the widespread vaccination program against measles and rubella, the systematic search of PVB19 in front of eruptive fevers becomes important.

HLA-E polymorphism and soluble HLA-E plasma levels in chronic hepatitis B patients

Chronic hepatitis B virus (HBV) infection occurs in association to a deregulation of immune system. Human leukocyte antigen E (HLA-E) is an immune-tolerant nonclassical HLA class I molecule that could be involved in HBV progression. To measure soluble (s) HLA-E in patients with chronic HBV hepatitis (CHB). We tested the potential association of HLA-E*01:01/01:03 A > G gene polymorphism to CHB. Our cohort consisted of 93 Tunisian CHB patients (stratified in CHB with high HBV DNA levels and CHB with low HBV DNA levels) and 245 healthy donors. Plasma sHLA-E was determined using enzyme-linked immunosorbent assay (ELISA). Genotyping was performed using polymerase chain reaction sequence-specific primer. No association between HLA-E*01:01/01:03 A > G polymorphism and HBV DNA levels in CHB patients was found. G/G genotype is less frequent in CHB patients without significance. sHLA-E is significantly enhanced in CHB patients compared with healthy controls (P = 0.0017). Stratification according to HBV DNA levels showed that CHB patients with low HBV DNA levels have higher sHLA-E levels compared with CHB patients with high HBV DNA levels. CHB patients with G/G genotype have enhanced sHLA-E levels compared with other genotypes (P = 0.037). This significant difference is maintained only for CHB women concerning G/G genotypes (P = 0.042). Finally, we reported enhanced sHLA-E in CHB patients with advanced stages of fibrosis (P = 0.032). We demonstrate, for the first time, the association of sHLA-E to CHB. Owing to the positive correlation of HLA-E*01:01/01:03 A > G polymorphism and the association of sHLA-E to advanced fibrosis stages, HLA-E could be a powerful predictor for CHB progression. Further investigations will be required to substantiate HLA-E role as a putative clinical biomarker of CHB.

Association of an HLA-G 14-bp Insertion/Deletion polymorphism with high HBV replication in chronic hepatitis

Identification of an HLA-G 14-bp Insertion/Deletion (Ins/Del) polymorphism at the 3' untranslated region of HLA-G revealed its importance in HLA-G mRNA stability and HLA-G protein level variation. We evaluated the association between the HLA-G 14-bp Ins/Del polymorphism in patients with chronic Hepatitis B virus (HBV) infection in a case-control study. Genomic DNA was extracted from 263 patients with chronic HBV hepatitis and 246 control subjects and was examined for the HLA-G 14-bp Ins/Del polymorphism by PCR. The polymorphic variants were genotyped in chronic HBV seropositive cases stratified according to HBV DNA levels, fibrosis stages and in a control population. There was no statistical significant association between the 14-bp Ins/Del polymorphism and increased susceptibility to HBV infection neither for alleles (P = 0.09) nor for genotypes (P = 0.18). The stratification of HBV patients based on HBV DNA levels revealed an association between the 14-bp Ins/Del polymorphism and an enhanced HBV activity with high HBV DNA levels. In particular, the Ins allele was significantly associated with high HBV DNA levels (P = 0.0024, OR = 1.71, 95% CI 1.2-2.4). The genotype Ins/Ins was associated with a 2.5-fold (95% CI, 1.29-4.88) increased risk of susceptibility to high HBV replication compared with the Del/Del and Ins/Del genotypes. This susceptibility is linked to the presence of two Ins alleles. No association was observed between the 14-bp Ins/Del polymorphism and fibrosis stage of HBV infection. We observed an association between the 14-bp Ins/Del polymorphism and high HBV replication characterized by high HBV DNA levels in chronic HBV patients. These results suggest a potential prognostic value for disease outcome evaluation.

[Parvovirus B19 seroprevalence in a group of schizophrenic patients]

BACKGROUND

Schizophrenia is a highly disabling chronic mental illness. It is considerded as a neurodeveloppemental illness resulting from the interaction of genetic and environmental factors. Growing evidence supports the major role of prenatal infections and inflammation in the genesis of schizophrenia. The hypothesis including viral infections has been the subject of several studies and the role of parvovirus B19 (PB19) in the onset of the disease has been suggested. However, there is, up till now, no seroepidemiological evidence of his involvement.

OBJECTIVE

To determine the prevalence of parvovirus B19 (PB19) in schizophrenic patients and in control subjects and to examine clinical associations between viral prevalence, risk factors of infectious disease and clinical features.

METHOD

We carried out a case-control seroepidemiological study in the Psychiatry department of Farhat-Hached general hospital of Sousse (Tunisia). We recruited108 schizophrenic patients and 108 healthy controls free from any psychotic disorder and matched for age and sex. We collected sociodemographic data, medical history, axis I comorbid disorders and infectious risk factors. We assessed patients for psychopathology and severity of illness using respectively the Brief Psychiatric Rating Scale (BPRS), the Scale for the Assessment of Positive Symptoms (SAPS), the Scale for the Assessment of Negative Symptoms (SANS), the Positive and Negative Syndrome Scale (PANSS) and the Clinical Global Impressions (CGI). For each study participant, blood sample was collected and levels of IgG and IgM anti-PB19 were measured using the ELISA technique.

RESULTS

The prevalence of IgG antibodies to PB19 was significantly higher in schizophrenic patients than in controls (73.1% vs 60.2%; P=0.04). There were no statistical differences between the two groups regarding the prevalence of IgM antibodies to PB19. No association was found between viral prevalence and sociodemographic data, risk factors for infection or clinical characteristics. The presence of PB19 antibodies was associated with a lower score on the PANSS negative subscale (P=0.04). No other signficative association were found.

CONCLUSIONS

In our study, prevalence of IgG antibodies to PB19 was significantly higher in schizophrenic patients than in controls. This finding supports the hypothesis of the involvement of PB19 in schizophrenia. Further studies including both virological and immunological aspects are needed to better clarify the etiopathogenic mechanisms of schizophrenia which would challenge the management of this disease.

Synthesis, structural characterization and dielectric properties of (C6H9N2)2(Hg0.75Cd0.25)Cl4 compound

The present paper undertakes the study of a title compound whose structure is (C6H9N2)2(Hg0.75Cd0.25)Cl4. The centrosymmetric compound crystallizes in the triclinic space group P-1, with a=7.580(7) Å; b=8.572(8) Å; c=15.433(13) Å; α=84.49(5)°; β=89.13(5)°; γ=68.53(5)° and Z=2. The crystal structure was solved and refined to R (int)=0.0212 using 7932 independent reflections. The atomic arrangement shows an alternation of organic and inorganic layers. Between layers, the cohesion is performed via N-H⋯Cl hydrogen bonding, yet in the organic sheets, cations are further connected to classical π-π stacking. The Infrared and Raman spectra of this compound reported from 400 to 4000 cm(-1) confirmed the presence of the principal bands assigned to the internal modes of organic cation. Solid-state (13)C and (111)Cd CP-MAS-NMR spectra are reported. The dielectric study of this compound has been measured, in order to determine the σ(d.c) conductivity which is thermally activated with activation energy about 1.5 eV.

[Seroprevalence and risk factors of human herpes virus 8 infection in Central-East Tunisia]

OBJECTIVE

Epidemiology of human herpesvirus 8 (HHV8) is still unknown in Tunisia. We aimed to assess the prevalence of HHV8 infection in adults and children from Central-East Tunisia and in patients with high risk of parenteral or sexual infection.

METHODS

We enrolled 553 subjects: 116 blood donors, 100 pregnant women, 100 children, 50 subjects with sexually transmitted infections with positive HIV serology and 50 other without HIV infection, 107 multitransfused patients and 30 kidney transplant patients. Antibodies against HHV8 were tested using a sensitive indirect immunofluorescence assay.

RESULTS

The seroprevalence of HHV8 was found to be 13.8% in blood donors, 13% in pregnant women and 12% in children. In healthy adult population, no association was found between HHV8 seropositivity and sex, sociodemographic characteristics, parenteral risk factors or serological markers of hepatitis B. Rates of HHV8 infection were significantly higher in patients having high-risk sexual behavior with or without HIV infection (P<10(-4)), in polytransfused patients (P<10(-4)) and in patients with kidney transplantation (P=0.001).

CONCLUSION

Our findings suggest that HHV8 infection is widespread in Central-East Tunisia such as in the Mediterranean area. HHV8 infection appears to be acquired early in life, probably through saliva. HHV8 transmission by blood transfusion, subject of controversy in literature, is well established in our study. Early screening of this infection should be considered in populations with high risk of Kaposi's sarcoma in our areas.

[Viral infection risk in polytransfused adults: seroprevalence of seven viruses in central Tunisia]

The aim of this study is to evaluate the prevalence of seven transfusion-transmitted viruses in polytransfused adults and children comparatively with a group of healthy control subjects. We studied 107 polytransfused patients (59 adults and 48 children) and 160 control subjects (100 blood donors and 60 children). Immunoenzymatic tests were used for detection of HBs antigen (HBs Ag), antibodies against hepatitis C Virus (anti-HCV), and human immunodeficiency virus (anti-HIV), and IgG antibodies against human cytomegalovirus (IgG anti-CMV), human parvovirus B19 (IgG anti-PB19), and hepatitis E virus (IgG anti-HEV). An immunofluorescent assay was performed for the detection of human herpesvirus 8 antibodies (anti-HHV8). Prevalence of HBs Ag, anti-HCV, anti-HIV, IgG anti-CMV, IgG anti-PB19, IgG anti-HEV, and anti-HHV8 in polytransfused group was 8.4, 4.7, 0, 86.9, 60.7, 28.9, and 47.6%, respectively, and 1.8, 0.6, 0, 86.2, 53.1, 10, and 12.5%, respectively, in the control group. The difference in prevalence between the two groups was statistically significant for HBs Ag (P = 0.01), anti-HCV (P = 0.03), IgG anti-HEV (P < 10(-4)), and IgG anti-HHV8 (P < 10(-4)). Categorization according to age showed that hepatitis B and C risk was limited in adult polytransfused group. HHV8 infection was higher in polytransfused subjects born before the use of leucocyte-depleted blood components. Our results corroborate literature data on the risk of HEV and HHV8 infection by blood transfusion. Hepatitis B vaccination and improvement in screening tests have an important role in reduction of hepatitis B and C risk in transfusion, especially in young polytransfused persons. However, a residual risk of transmitting viral infections persists, and efforts are needed to improve transfusion safety.

Polarized Raman study of [N(C3H7)4]2Cd2Cl6 single crystal

Chemical preparation, mid-infrared and Raman spectra of [N(C(3)H(7))(4)](2)Cd(2)Cl(6) are presented. Polarized Raman spectra of oriented single crystals have been recorded in the range 7-3900 cm(-1) under various polarization configurations with regard to the symmetry and the numbers of several band modes observed in the Raman and infrared spectra. The obtained results are consistent with the theoretical predictions based on the infrared and Raman selection rules.

[Risk of vertical transmission of hepatitis B virus in Tunisia]

The risk of vertical transmission of hepatitis B virus (HBV) varies with type of viral endemicity, degree of maternal infection and genomic characteristics of the virus. The aim of this study is to estimate this risk in Tunisia using serological and molecular methods to evaluate HBV replication, to determine viral genotypes and to detect presence of occult hepatitis in 2709 pregnant women. Serological markers were detected by ELISA methods, Genotype was determined by PCR-RFLP and occult hepatitis by nested-PCR. Four percent of women were positive for HBsAg; only 3% of them were also positive for HBeAg. Viral replication, over than 10(3) copies/ml, was detected in 61% of positive HBsAg patients. Three viral genotypes were detected: D (95%), B (3%) and A (3%). Occult hepatitis was detected in 4% of sera with "anti-HBc isolated" profile. In conclusion, the risk of vertical transmission of HBV exists in Tunisia. It increases by frequency of precore mutants, predominance of the genotype previously associated with high levels of replication and possibility of occult hepatitis B. These results show the importance of screening by serological HBV markers systematically during pregnancy with evaluation of viral replication in order to prevent vertical risk by efficient tools.

[Seroprevalence and risk factors of hepatitis E among pregnant women in central Tunisia]

OBJECTIVES

The study was conducted to investigate the prevalence and risk factors for hepatitis E virus (HEV) infection in Tunisian pregnant women.

METHODS

A total of 404 pregnant women were enrolled. Data were collected through a standard questionnaire which covered sociodemographic characteristics and risk factors. Blood samples were collected and were tested for HEV IgM and IgG antibodies, IgG against hepatitis A (anti-HAV IgG), hepatitis B virus surface antigen (HBsAg) and hepatitis C virus antibody (anti-HCV). Risk factors were analyzed using univariate and multivariate logistic regression models.

RESULTS

Prevalence of anti-HEV IgG, anti-HEV IgM, anti-HAV IgG, HBs Ag and anti-HCV was 12.1 %, 0 %, 97 %, 3 % and 0,5 %, respectively. In multivariate analysis age (>30 years) and the number of persons per room (>2) in the house were independent factors predicting HEV infection. History of agricultural work, kind of water, sewage treatment, use detergent to wash vegetables, contact with animals and parenteral risk factors were not correlated with the presence of anti-HEV IgG.

CONCLUSION

The important seropositive rate among pregnant women is compatible with endemicity of HEV in Tunisia. Hepatitis E should be considered in the diagnosis of acute hepatitis during pregnancy. Our result suggests that infection occurs sporadically by person-to-person transmission route but further investigations are needed to determine the natural reservoir of infection.

Facteurs de risque du portage du streptocoque du groupe B chez la femme enceinte à terme: étude prospective à propos de 294 cas

OBJECTIVE

To determine the rate and risk factors for group B streptococcus (GBS) colonization in term pregnancies.

PATIENTS AND METHODS

Vaginal and anal cultures were prospectively conducted in 294 parturient on admission for term vaginal delivery.

RESULTS

Thirty-eight (12.92%) parturient had positive GBS cultures. None of the studied risk factors (age, education status, nulliparity, previous obstetric problem, twin pregnancy and diabetes) was statistically predictive of maternal colonization. All the isolated GBS were sensitive to the penicillin G.

DISCUSSION AND CONCLUSION

Systematic screening strategy of GBS close to the delivery on all pregnant women is desirable.

[Multiclonality of methicilin-resistant Staphylococcus aureus in a university hospital]

OBJECTIVE

The methicillin resistance of Staphylococcus aureus MRSA is a major problem for human infections. The authors present a genotypic study of these bacteria to understand the spreading of these strains in a university hospital.

PATIENTS AND METHODS

We collected 19 strains of MRSA (September 2003-March 2004) for which the presence of gene mecA had been confirmed by PCR. They were then genotyped in pulsed-field Gel electrophoresis (CHEF variety).

RESULTS

Resistant strains accounted for 12.9% of all collected S. aureus strains. Most samples came from patients hospitalized or consulting in dermatology. Eleven different antibiotypes and four genotypic profiles were determined: type A (with 8 subtypes), type B (with 2 subtypes), type C, and D.

CONCLUSION

MRSA strains have a multiclonal distribution in our hospital with a dominant endemic clone in the dermatological unit. Skin infections are the main hospital source for these strains.

[Outbreak of nosocomial urinary tract infections due to a multidrug resistant Pseudomonas aeruginosa]

An outbreak of a multidrug resistant Pseudomonas aeruginosa including imipenem resistance occurred in the urology intensive care unit at Charles Nicolle Hospital (Tunis). All isolates presented the same antibiotic resistance pattern and were only susceptible to colistin. The epidemic strain was detected in different sites of this unit. Pulsed-field gel electrophoresis after enzymatic restriction using XbaI was performed in order to establish an epidemiologic link between these infections. Genotypic analysis showed two different patterns and the environmental source was identified in both cases. Although the same antibiotype was harbored by all the isolates, two outbreaks occurring in the same period were identified. The strengthening of hygiene measures allowed to stop the outbreak spreading. Since the hospital environment is the major source of Pseudomonas aeruginosa contamination, a continuous surveillance of the patients and the environmental sources is required for the implementation efficient control measures.

[Genotypic exploration of a hospital neonatal outbreak due to Klebsiella pneumoniae producing extended-spectrum-betalactamase]

BACKGROUND

The aim of the study was to explore nosocomial neonatal outbreak of Klebsiella pneumoniae producing extended-spectrum-betalactamase by macrorestriction genotyping.

PATIENTS AND METHODS

Over a 25 days period, a hospital neonatal outbreak due to Klebsiella pneumoniae producing extended-spectrum-betalactamase affected 14 newborn infants admitted to a university hospital in Sousse (Tunisia). We collected 21 strains of Klebsiella pneumoniae producing extended-spectrum-betalactamase. Susceptibility testing to 17 antibiotics was determined. Macrorestriction genotyping of strains was determined by pulsed-field-electrophoresis. Neonatal intensive care unit survey was undertaken.

RESULTS

A macrorestriction genotyping subdivided 21 strains into 3 clonally groups. Only cefoxitin, colistin, imipenem, amikacin and quinolons were active on the whole of strains. All infected babies died. The hygiene insufficiency and contamination of transfusion products at the time of their dividing in neonatal intensive care unit were incriminated. Handholding due to work overcharge was the main cause of bacterial diffusion.

CONCLUSION

Multiclonal outbreak of Klebsiella pneumoniae producing extended-spectrum-betalactamase appeared following hygiene insufficiency related to work overcharge.

[Vascular complications in infectious endocarditis. Apropos of 86 cases]

During a 20 year period, 285 patients were hospitalised for infectious endocarditis (IE) in the Department of Cardiology of the Ernest-Conseil Hospital in Tunis and 86 of them, i.e. 30%, developed a vascular complication (VC). Among these 86 patients, there were a total of 108 lesions, including 52 neurological complications, 14 peripheral acute ischemic syndromes, 16 peripheral arterial aneurysms, 9 aortic aneurysms, 7 pulmonary embolisms, 6 splenic infarctions and 4 coronary lesions. The mortality in this patient group proved to be slightly greater than in the series as a whole, in particular concerning patients with multiple lesions and those with an artificial valve. No prognostic difference was seen between patients with a VC of aneurysmal type and of ischemic type, but the presentation and severity of lesions was very variable. The vascular complication was a presenting feature of IE in almost 40% of cases. The organism found most often was the streptococcus, above all in ischemic type IE as well as in the total patient group. Similarly, the preferential site was aortic, above all for aneurysmal type IE. Ultrasonography revealed a higher incidence of vegetations in this series of patients, above all in ischemic type VC, but anatomical studies have shown this to be an investigation of moderate sensitivity and poor specificity, poorly correlated from a prognostic standpoint with the risk of embolism. The conclusion of the study is above all the need to prevent such complications: embolic complications by early antibiotic treatment and valve replacement and aneurysmal complications by methodical routine angiographic evaluation and appropriate treatment.

[Neurologic manifestations of infectious endocarditis]

Thirty out of 287 patients (10.4%) admitted to hospital for infective endocarditis between December 1970 and January 1990 had neurological complications. Twenty-three patients had native valve infectious endocarditis and 7 had prosthetic valve endocarditis. The clinical features were characterized by the frequency of aortic valve involvement (23 out of 30) and other complications, especially cardiac failure (16 cases) and peripheral vascular manifestations (7 cases). The commonest organism was the staphylococcus (53% of identified organisms) but the number of negative blood cultures was high (50% of cases). The neurological complication was often the presenting symptom of the endocarditis (19 cases) but it occurred after bacteriological cure in 4 cases. The complications observed were cerebral ischemia (16 cases), cerebral haemorrhage (11 cases), coma (2 cases), and one peripheral neuropathy causing a Claude Bernard Horner syndrome. These complications presented with hemiplegia in 17 cases, a meningeal syndrome in 8 cases, a convulsion in 1 case, a Von Wallenberg syndrome in 1 case, and a Claude Bernard Horner syndrome in 1 case. Twelve patients had a transient or permanent neurological coma. Cerebral CT scan showed ischemic lesions in 7 cases and haemorrhagic lesions in 10 cases. Carotid angiography demonstrated mycotic aneurysms in 6 patients. Twelve patients died: the cause of death was neurological coma (7 cases), low cardiac output (4 cases) and haemorrhagic shock (1 case). Four patients underwent neurosurgery: 3 for clipping a mycotic aneurysm and 1 for drainage of an intracerebral haematoma. Poor prognostic factors were: coma, cardiac failure, cardiac valve prosthesis and, above all, the extent and multiplicity of the neurological lesions. The authors propose the following measures to improve the prognosis: early surgery in cases of large and/or mobile vegetations especially when the infecting organism is a staphylococcus and when a systemic embolism has occurred; routine CT scanning and/or digitised cerebral angiography in all patients with infective endocarditis to detect surgically accessible mycotic aneurysms.

[Treatment of chronic refractory cardiac insufficiency with enalapril]

The objective is here to study the long and intermediate term clinical and haemodynamic effects of enalapril during chronic heart failure resistant to the classic digitalis-diuretics treatment. The study involves 16 patients (12 males and 4 females), with a mean age of 50 years. Before being given enalapril, 12 patients were at stage IV and 4 patients at stage II of the NYHA; the mean capillary pressure was quite elevated (30 +/- 6.3 mmHg), the cardiac index has collapsed (2.12 +/- 0.38 l.min.m2) and the stroke fraction (SF) is 0.28 +/- 0.08. At the 1st month control, there is a definite functional and haemodynamic improvement of the pre-charge as well as the post-charge. This improvement is still present at 6 months. The ventricular function is improved (SF = 0.38 +/- 0.13; p less than 0.001). The clinical tolerance of enalapril is excellent and the only adverse reaction is a transient deterioration of the renal function in a patient with diabetic glomerulopathy.

[Auriculoventricular blocks in the acute phase of myocardial infarction. Course and prognosis. Apropos of 90 cases]

The objective is to study the clinical and electrocardiographic characteristics as well as the course of myocardial infarction complicated by atrio-ventricular block (AVB), and to propose a management to acute myocardial infarction with A-V block. This study concerns 90 patients (78 men and 12 women), with a mean age of 58 years. The overall frequency of AVB is 7.6 p. cent. The infarction is most of the time found posteriorly (51 p. cent of the cases). Syncopes are essentially seen in complete AVB (81 p. cent) and with deep antero-septal necrosis (73 p. cent). Heart failure is especially the complication of anterior (73 p. cent) and deep septal (78 p. cent) necrosis. The mortality of myocardial infarction complicated by A-V block (41 p. cent) is higher than that of uncomplicated necroses (15 p. cent). The prognosis is usually favorable in posteriorly located infarctions where the A-V block is usually regressive and benign while it is much more severe in other locations where the conduction disorders associated with severe myocardial lesions. Temporary and/or permanent electrosystolic stimulation must be well codified in its indications which should be broadened, especially in case of anterior or deep septal necrosis.

Prosthetic valve endocarditis. A survey

Fifty eight patients (aged 8-59 years, mean 27) treated for prosthetic valve endocarditis from January 1966 to January 1985 were studied retrospectively by review of case notes. There were 12 cases of early and 46 cases of late prosthetic valve endocarditis. These developed in 28 patients with an isolated aortic valve, in 26 with an isolated mitral valve, and in four with both aortic and mitral prosthetic valves. Streptococci were the most commonly isolated microorganisms, followed by staphylococci, Gram negative bacteria, and fungi. A surgical (34 cases) or a necropsy specimen (10 cases) from 44 cases was examined. Eighty two per cent of the patients had congestive heart failure. Twenty four of the 58 patients were medically treated and 17 died (70% mortality). Combined medical and surgical treatment was used in 34 patients; the main indication for surgery was congestive heart failure. Fourteen patients on combined treatment died (40% mortality). Persistent sepsis and prosthetic valve dehiscence were the most common early and late operative complications. The most important influences on outcome were congestive heart failure, the type of micro-organism, the severity and extent of anatomical lesions, the time of onset of prosthetic valve endocarditis, and the type of treatment. This survey indicates that only patients without congestive heart failure or embolic complications and with sensitive micro-organism should be treated medically. In view of the poor prognosis patients with prosthetic valve endocarditis associated with congestive heart failure, persistent sepsis, and repeat arterial emboli should be treated by early surgical intervention.

[Early and late hospital mortality in myocardial infarction. Causes and prognostic factors. Apropos of 140 cases]

The purpose of this work is to study the causes of early and late in-hospital mortality of myocardial infarction, to define elements of prognosis and to attempt to prevent the fatal outcome of the coronary disease. This study concerns 107 men and 33 women, between the ages of 30 and 83 years (mean age 62.8 years). The total mortality is 12% (early: 6.5%, late: 5.5%. 66% of the patients are over 60 and 45% present 3 or more coronary risks factors. The clinical picture is characterized by frequent initial complications (84% of the cases), dominated by hemodynamic failure. The infarction is most of the time located anteriorly (56.6% of the cases). Primary cardiogenic shock represents the main cause of early mortality (55.3%). A recurrent infarction represents 75% of the causes of late deaths. Tri-vessels involvement and alteration of the ventricular function are noted in 9 out of 14 coronary arteriograms. Prognosis factors are proposed to differentiate high risk patients requiring an early coronary arteriogram in view of a specific medical and/or surgical treatment. The best signs of a poor prognosis are: tri-vessels involvement and alteration of the ventricular function.

[Infectious endocarditis surgically-treated in the active phase. Apropos of 46 cases]

The clinical and microbiological characteristics, the surgical indications and procedures, the evolution and the principal prognostic factors were reviewed in 46 cases of infectious endocarditis operated in the active phase. Using this date, the authors try to determine the optimal time for surgery during the acute active phase of infectious endocarditis. The study population comprised 28 men and 18 women aged 7 to 64 years (average age: 30). The patients were selected on strict criteria: positive blood cultures during the 48 hours prior to surgery (29 cases), positive valve or valve prosthesis culture (15 cases), the presence of an active cardiac abscess at surgery (7 cases), the presence of a large number of bacteria on histological examination of the valve (17 cases). The patients were divided into two groups: those with endocarditis of native valves (27 cases) and those with endocarditis on prosthetic valves (19 cases). The preoperative clinical features included all the classical signs of IE but congestive cardiac failure was particularly prevalent (62% of cases). Microbiologically, most cases of native valve endocarditis (67%) were due to sensitive organisms (streptococci) whilst the more virulent organisms (staphylococci, gram-negative bacteria and fungi) were observed in prosthetic valve endocarditis (64% of cases). The commonest surgical indication was haemodynamic deterioration (30 cases). The indications were mixed in 15 cases but only one case was operated for uncontrolled infection alone in this series. The surgical procedure was technically complex in 6 cases. Operative mortality was high (18 cases, 39%). The main cause of death was low cardiac output (13 cases).(ABSTRACT TRUNCATED AT 250 WORDS)

[Long-term clinical and hemodynamic results of the treatment of refractory cardiac failure with molsidomine]

Molsidomine, one of the sydnonimine group of drugs; the object of this study was to evaluate its efforts in refractory cardiac failure. In the first part of the study, the haemodynamic effects of a single oral dose of 2 or 4 mg of molsidomine were compared with placebo controls in 23 patients. This showed molsidomine to be an active venous vasodilator reducing pulmonary artery and right atrial pressures without changing cardiac index or systemic pressures. The peak effect was observed after 1 to 1,5 hours. In the second phase, molsidomine was used in 9 patients aged 32 to 71 years (mean 47 +/- 12 years) over an average period of 19 months (3,5 to 42 months). The maintenance dose varied from 8 to 24 mg/24 hours. These patients had refractory cardiac failure secondary to primary cardiomyopathy with dilatation (6 cases) or ischemic heart disease (3 cases). The 9 patients were in functional classes IV (5 cases) or III (4 cases). Four patients were theoretically good indications for transplantation. Haemodynamic control was performed 1,8 +/- 5 months after a washout period of 8 hours, and after initial right heart catheterisation, the measurements were repeated 1 hour after oral administration of a 4 mg dose of molsidomine. Two patients did not respond initially to molsidomine; one died, the other remained in functional Class III. Another patient who responded initially was improved for over two years but died in cardiac failure after 42 months' treatment. The other six patients have been significantly improved and were in functional Class II at their last control.(ABSTRACT TRUNCATED AT 250 WORDS)