Phenotypic and genotypic characterization of meningococcal isolates in Tunis, Tunisia: High diversity and impact on vaccination strategies.

OBJECTIVES: The aim of this study was to characterize Neisseria meningitidis (Men) isolates in Tunisian paediatric patients with invasive meningococcal disease (IMD) in order to target therapeutic and preventive strategies. METHODS: Fifty-nine isolates of Men and four cerebrospinal fluid samples that were culture-negative but Men-positive by PCR (NC-MenPPCR) (2009-2016) were collected from IMD patients. Isolates were analysed for their antimicrobial susceptibility. Whole-genome sequencing (WGS) was used to characterize isolates and multilocus sequence typing for NC-MenPPCR. Coverage of Men serogroup B (MenB) was determined by Genetic Meningococcal Antigen Typing System (gMATS) and fHbp expression by ELISA. RESULTS: MenB was the predominant type (88.9%). The majority of isolates (81%) had reduced susceptibility to penicillin G with altered penA alleles. The clonal complex CC461 (27.1%) was the most frequent. Among the MenB vaccine targets neisserial heparin binding antigen (NHBA) and fHbp, the predominant variants were NHBA118 (30.8%) and fHbp peptide 47 (25%), respectively. The nadA gene was present in 17.3% of isolates. Using gMATS, 36.5% of MenB were predicted to be covered by the 4CMenB vaccine. ELISA showed that 92.4% of the MenB were expected to be killed by anti-fHbp antibodies. CONCLUSIONS: MenB was the leading serogroup in IMD, and more than 90% had a sufficient level of fHbp expression for vaccine coverage. The study results will be useful for the Tunisian vaccination programme.

Seroprevalence of Bordetella pertussis toxin antibodies in children and adolescents in Tunis, Tunisia.

Pertussis remains a public health concern in most countries. This cross-sectional study aims to investigate the distribution of pertussis toxin antibodies (anti-PT IgG) in Tunisian children and adolescents aged 3-18 years, to define optimal age for booster vaccination. Anti-PT IgG concentrations of enrolled participants were measured using commercial enzyme-linked immunosorbent assay. Concentrations were classified as: indicative of current/recent infection if ⩾100 IU/ml, indicative of recent exposure to Bordetella pertussis within the last year if 40-100 IU/ml and less likely revealing a recent exposure to B. pertussis if <40 IU/ml. Between March and June 2018, a total of 304 participants (mean age: 9.3 years) were included in this study. Overall, 12.8% (95% confidence interval (CI) 9.1%-16.6%) were seropositive (IgG levels ⩾40 IU/ml). Among them, 14.7% (95% CI 2.3%-23.3%) had levels indicative of a current/recent infection. The multivariate Poisson regression analysis suggested associations between female gender, as well as age group 13-18 years and 3-5 years and higher anti-PT IgG concentrations. Our results are consistent with the notion that vaccine-induced immunity decline, as well as circulation of pertussis among school children and adolescents enables them to be reservoirs of infection and disease transmission to vulnerable infants. Booster dose of acellular pertussis vaccine for school entrants is therefore recommended.

Characterization of invasive Neisseria meningitidis strains isolated at the Children's Hospital of Tunis, Tunisia.

Neisseria meningitidis, a leading cause of bacterial meningitis and other serious infections, is responsible for approximately one-third of cases of bacterial meningitis in the Children's Hospital of Tunis. The serogroup distribution, antibiotic susceptibility and antigenic and molecular characteristics of N. meningitidis isolates were determined in patients aged 3 days-13 years between February 1998 and June 2013. In all 107 invasive strains of N. meningitidis were isolated. Reduced susceptibility to penicillin G was seen in 55.7% of isolates, with a low level of resistance in all cases; 28.4% showed a low level of resistance to amoxicillin. Serogroup B isolates were the most frequent (80.4%), followed by serogroups C (12.2%) and A (5.6%). Isolates of serogroup A had the same antigenic formula (A:4:P1.9), the same variable regions VR1, VR2 and VR3, and belonged to the same clonal complex (CC5). Isolates of serogroups B and C were more heterogeneous with several antigenic formulae. The most frequent clonal complex in these isolates was CC35. Serogroup B accounted for a large percentage of our isolates with marked diversity.

[Seroprevalence of human parvovirus B19 in children with fever and rash in the North of Tunisia]. / Prévalence de l'infection par le parvovirus B19 humain au cours des éruptions fébriles de l'enfant dans le Nord tunisien.

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.

Characterization of invasive Neisseria meningitidis strains isolated at the Children's Hospital of Tunis, Tunisia

Neisseria meningitidis, a leading cause of bacterial meningitis and other serious infections, is responsible for approximately one-third of cases of bacterial meningitis in the Children's Hospital of Tunis. The serogroup distribution, antibiotic susceptibility and antigenic and molecular characteristics of N. meningitidis isolates were determined in patients aged 3 days-13 years between February 1998 and June 2013. In all 107 invasive strains of N. meningitidis were isolated. Reduced susceptibility to penicillin G was seen in 55.7% of isolates, with a low level of resistance in all cases; 28.4% showed a low level of resistance to amoxicillin. Serogroup B isolates were the most frequent [80.4%], followed by serogroups C [12.2%] and A [5.6%]. Isolates of serogroup A had the same antigenic formula [A:4:P1.9], the same variable regions VR1, VR2 and VR3, and belonged to the same clonal complex [CC5]. Isolates of serogroups B and C were more heterogeneous with several antigenic formulae. The most frequent clonal complex in these isolates was CC35. Serogroup B accounted for a large percentage of our isolates with marked diversity

La bactérie Neisseria meningitidis, l'une des causes principales de méningite bactérienne et d'autres infections graves, est responsable d'environ un tiers des cas de méningite bactérienne à l'Hôpital d'enfants de Tunis. La distribution par sérogroupe, la sensibilité aux antibiotiques et les propriétés antigéniques et moléculaires des isolats de N. meningitidis ont été déterminées chez des patients âgés de 3 jours à 13 ans entre février 1998 et juin 2013. En tout, 107 souches invasives de N. meningitidis ont été isolées. Une sensibilité réduite à la pénicilline G a été observée dans 55,7% des isolats, avec un bas niveau de résistance pour tous les cas ; et 28,4% ont montré un bas niveau de résistance à l'amoxicilline. Les isolats du sérogroupe B étaient les plus fréquents [80,4%], suivis par les sérogroupes C [12,2%] et A [5,6%]. Les isolats du sérogroupe A avaient la même formule antigénique [A:4:P1.9], les mêmes régions variables VR1, VR2 et VR3, et appartenaient au même complexe clonal [CC5]. Les isolats des sérogroupes B et C étaient davantage hétérogènes, avec plusieurs formules antigéniques. Le complexe clonal le plus fréquent de ces isolats était CC35. Le sérogroupe B comptait pour un pourcentage élevé des isolats avec une diversité marquee

Prevalence, identification by a DNA microarray-based assay of human and food isolates Listeria spp. from Tunisia.

OBJECTIVES: We aimed at evaluating the prevalence of Listeria species isolated from food samples and characterizing food and human cases isolates. MATERIAL AND METHODS: Between 2005 and 2007, one hundred food samples collected in the markets of Tunis were analysed in our study. Five strains of Listeria monocytogenes responsible for human listeriosis isolated in hospital of Tunis were included. Multiplex PCR serogrouping and pulsed field gel electrophoresis (PFGE) applying the enzyme AscI and ApaI were used for the characterization of isolates of L. monocytogenes. We have developed a rapid microarray-based assay to a reliable discrimination of species within the Listeria genus. RESULTS: The prevalence of Listeria spp. in food samples was estimated at 14% by using classical biochemical identification. Two samples were assigned to L. monocytogenes and 12 to L. innocua. DNA microarray allowed unambiguous identification of Listeria species. Our results obtained by microarray-based assay were in accordance with the biochemical identification. The two food L. monocytogenes isolates were assigned to the PCR serogroup IIa (serovar 1/2a). Whereas human L. monocytogenes isolates were of PCR serogroup IVb, (serovars 4b). These isolates present a high similarity in PFGE. Food L. monocytogenes isolates were classified into two different pulsotypes. These pulsotypes were different from that of the five strains responsible for the human cases. CONCLUSION: We confirmed the presence of Listeria spp. in variety of food samples in Tunis. Increased food and clinical surveillance must be taken into consideration in Tunisia to identify putative infections sources.

Non-susceptibility trends and serotype coverage by conjugate pneumococcal vaccines in a Tunisian paediatric population: a 10-year study.

Streptococcus pneumoniae is one of the major causative agents of invasive infectious disease in children <5 years old globally. The aim of this study was to analyze the antimicrobial resistance and the serotype distribution of S. pneumoniae isolates from the paediatric population in Tunisia and to specify the serotypes coverage by the conjugate pneumococcal vaccines. Antimicrobial susceptibility was determined by the disk diffusion method. Minimal inhibitory concentrations of beta-lactams were determined using the E test method (AB BIODISK). Serotypes were determined by agglutination of latex particles, which identified a subset of serotypes included in pneumococcal conjugate vaccines (1, 3, 4, 5, 14) and some of the serogroups. This was followed by the Neufeld test using monovalent antisera (Statens Serum Institute) specific for the other serotypes included in pneumococcal conjugate vaccines 7, 10 and 13 (PCV7, PCV10, PCV13): 6A, 6B, 7F, 9V, 18C, 19A, 19F and 23F. During the study period, 200 invasive and 310 non-invasive pneumococcal isolates were obtained from paediatric patients ranging in age from newborn to 16 years. Among these 510 isolates, 53.4% had reduced susceptibility to penicillin. Penicillin resistance was higher among S. pneumoniae isolates recovered from samples associated with non-invasive vs. invasive disease (60.6% vs. 45%). All the strains were susceptible to pristinamycin, vancomycin, teicoplanin and fosfomycin. Serotype 14 was the most frequently isolated serotype (22.2%), followed by serotypes 19F (15.5%) and 23F (10.3%). Of all strains typed, the percentage of serotypes covered by PCV7, PCV10 and PCV13 were 66.4%, 73% and 78%, respectively (76.1% for invasive pneumococcal isolates, 79.8% for non invasive pneumococcal isolates for PVC13). Continual surveillance of antibiotic susceptibility and careful use of antibiotics are recommended. The introduction of the new conjugate vaccine should be greatly beneficial for reducing pneumococcal invasive diseases among Tunisian children.

Dual infection with Bordetella pertussis and Mycoplasma pneumoniae in three infants: case reports.

Studying pertussis-like respiratory infections, we report the cases of three infants with evidence of both Bordetella pertussis and Mycoplasma pneumoniae. Bordetella infection was identified by the real-time polymerase chain reaction (RT-PCR) of nasopharyngeal specimens. Neither B. pertussis nor B. parapertussis were recovered on the culture of nasopharyngeal aspirates (NPAs) from any subjects. M. pneumoniae etiology was diagnosed by culture and RT-PCR. The evolution was fatal for all of the subjects. We conclude that, among patients with Bordetella infection, co-infection with another respiratory pathogen is often probable, and these mixed infections might cause a more severe form of illness, sometimes leading to death.

Microbiological profile of haematogenous osteoarticular infections in children.

INTRODUCTION: Staphylococcus aureus, Kingella kingae and ß-hemolytic streptococcus are presently the most frequently identified bacteria in child haematogenous osteoarticular infection. OBJECTIVE: To determine the microbiological profile (bacteria and antibiotic susceptibility) of osteoarticular infections in a paediatric hospital, so as to adapt treatment protocols to the ecology of the bacteria isolated. PATIENTS AND METHODS: Prospective descriptive study, including children admitted for acute osteomyelitis or septic arthritis. A series of blood cultures was performed systematically on admission. In case of surgery, local samples were taken for bacteriology. Antibiotherapy was initiated and subsequently adapted to the bacteriological findings. RESULTS: One hundred and six children were included. Thirty-five were under (Group 1) and 71 over 3 years of age (Group 2). Ninety-five underwent surgery. Peroperative samples were positive in 61 cases and blood culture in 23. Bacteria were isolated in 22 patients in G1. Extended-spectrum ß-lactamase-producing Klebsiella pneumoniae was isolated in five neonates who had passed through intensive care. Staphylococcus aureus was the most frequently isolated bacterium in G2 (n=40), and was methicillin-resistant (MRSA) in six children. DISCUSSION: Methicillin-susceptible Staphylococcus aureus was the most frequently isolated microorganism. Other than neonates who had passed through intensive care and the six patients with community-acquired MRSA infection, all isolated bacteria were susceptible to second-generation cephalosporins. LEVEL OF EVIDENCE: II, prospective descriptive prognostic study.

[The re-emergence of pertussis in Tunisia]. / La réémergence de la coqueluche en Tunisie.

OBJECTIVE: The authors had for aim to analyze pertussis epidemiology in Tunisia by studying nasopharyngeal specimens of infants hospitalized in Tunis. METHODS: Between march 2007 and march 2008, clinical nasopharyngeal samples were collected from infants with a suspected diagnosis of whooping cough, pertussoid cough, or pertussis-like syndrome, admitted at the Tunis children's hospital. The laboratory diagnostic criteria were culture isolation of Bordetella species on Bordet-Gengou medium and real-time PCR. RESULTS: Fifty-nine percent of the 74 investigated children with suspected pertussis were less than two months of age. The diagnosis of pertussis was proved positive by real-time PCR for 41%. Culture was negative in all cases. CONCLUSIONS: Whooping cough is still prevalent in Tunisia despite an important vaccination coverage. Real-time PCR is an invaluable tool for the rapid diagnosis of pertussis, however culture must also be associated.

[Listeriosis in Tunis: seven cases reports]. / Les infections à Listeria monocytogenes à Tunis: à propos de sept cas.

Listeria monocytogenesis a Gram positive facultative intracellular bacterium that can be responsible for severe infections, affecting essentially pregnant women, immunocompromised patients at the early and later stages of life. In Tunisia, invasive L. monocytogenes infections are thought to be exceptional and limited data are available about listeriosis. We reported seven cases (five newborn children and two infants) of human listeriosis that occurred in Tunis from 2000 to 2008. The newborn children were hospitalized for suspicion of maternofoetal infections. The two infants were hospitalized for fever associated with digestive signs in one case and neurological signs in the other. L. monocytogenes-was isolated from culture of cerebrospinal fluid in four cases, peripheral samples in two cases and from blood culture in one case. Isolates identification was based on conventional methods. Antimicrobial susceptibility was realized according to the recommendation of the "Comité de l'antibiogramme de la Société française de microbiologie". All L. monocytogenes isolates were sensitive to amoxicillin and aminoside but resistant to 3rd generation cephalosporins. Investigations of the immune system were realized for the two infants including phenotypic analysis of peripheral blood cells by flow cytometry, lymphocyte proliferation assays, phagocytic cell functions and measurement of immunoglobulins as well as complement. All these explorations were normal for both infants. The outcome was fatal in only one case (a newborn child), and all the other patients recovered after adapted antibiotic treatment. In conclusion, our study shows that listeriosis is not exceptional in Tunis. Thus, it is necessary to know how to evoke this diagnosis, at any age, in order to establish an early and adapted antibiotic treatment and to avoid fatal outcome.

Molecular analysis of community-acquired methicillin-susceptible and resistant Staphylococcus aureus isolates recovered from bacteraemic and osteomyelitis infections in children from Tunisia.

Thirty-six children (27 boys, nine girls) that fulfilled CDC criteria for community-acquired infections were diagnosed with bacteraemia and/or osteomyelitis caused by Staphylococcus aureus during an 18-month period (2006-2008). Antibiotic susceptibility was determined by an agar dilution method. SCCmec type, carriage of pvl genes, agr type and spa-typing were determined using specific PCR protocols. Clonal relatedness was examined by pulsed field gel electrophoresis-SmaI and mutilocus sequence typing techniques. From the 36 isolates, eight (22%) corresponded to methicillin-resistant Staphylococcus aureus (MRSA) -t044/042-CC80/CC5-IVc-pvl(+) -agrIII/II. The highest genetic diversity was observed among the 28 community-acquired methicillin-susceptible S. aureus (CA-MSSA) isolates: 22 spa-variants that also grouped by multilocus sequence typing in CC1, CC5, CC6, CC8, CC30, CC80, CC97 and the singletons ST464, ST1467, ST1468 and ST1469. The pvl genes were detected in all eight CA-MRSA isolates and in eight CA-MSSA isolates (28%), being significantly more frequent among isolates causing osteoarticular infection (11 of 12, 92%) than in the bacteraemic isolates (six of 24, 25%). Based on patients' age, three groups were considered: newborns, infants and children. Bacteraemia was diagnosed in all newborns and infants, whereas in 42% of the children group osteomyelitis was the unique presentation. In most cases, the portal of entry was either the skin or unknown. In general, favourable outcome was observed, except in four cases-three of whom had severe complications and one died. In summary, we analysed the epidemiological and genetic background of community-acquired staphylococcal strains causing bacteraemic and/or osteomyelitis infections in children from Tunisia, describing three new sequence types and one novel spa type.

[Iatrogenic meningitis after diagnosis lumbar puncture: 3 cases reports in the paediatric Children's Hospital of Tunis]. / Méningite bactérienne iatrogène après ponction lombaire de diagnostic: à propos de trois cas observés à l'hôpital d'enfants de Tunis.

We have collected cases of iatrogenic meningitis managed in the Children's Hospital of Tunis, between January 1998 and December 2006. Clinical information about each patient were collected, all bacterial samples were investigated in the microbiology laboratory of the hospital. Bacterial isolates were identified according to conventional criteria. In the interval under study, we recorded three cases of iatrogenic meningitis after lumbar puncture. Two cases occurred in newborn admitted for suspicion of neonatal infection and one in a 2-month-old infant admitted for exploration of hyperpyretic convulsion. In all patients, the initial cerebrospinal fluid was normal. All patients developed symptoms of acute meningitis within 72 hours after lumbar puncture; the second cerebrospinal fluid was, then, typical for purulent meningitis. The causal agents isolated in the three cases were Klebsiella pneumoniae, Enterobacter cloacae, and Serratia marcescens, all resistant to beta-lactams by extended spectrum beta-lactamase production. The use of quinolones was required in all cases. Different complications were recorded: hydrocephalus and brain abscess in one case, respiratory and hemodynamic failure managed in the intensive care unit in the second, and brain hygroma in the third case. This study shows high morbidity of iatrogenic meningitis. Simple aseptic precautions undertaken before the procedure of lumbar puncture can prevent such cases. The urgent need for increasing the awareness among medical personnel in hospitals of developing countries cannot be overemphasized.

[Neisseria meningitidis invasive infections in children in Tunis: about 79 cases]. / Les infections invasives a Neisseria meningitidis chez l'enfant a Tunis : a propos de 79 cas.

We conducted a retrospective study of meningococcal invasive diseases (MID) contracted in children in Tunis between January 1997 and January 2006. The purpose of this study is to specify the clinical, epidemiological, therapeutic and evolutionary features of these infections and to determine antimicrobial susceptibility and the antigenic formula of N. meningitidis isolates. During the study period, we have collected 79 cases of MID arising in children aged 3 days to 11 years. The majority of children's were less than of 4 years (57.3%). We note a frequency of the MID in winter and in spring. The most frequent clinical shape was meningitis (53%). Twenty one patients (26.6%) had a fulminant meningococcal disease. In our series, the rate of lethality was equal to 17.7%. Among the 46 meningococcal isolates, the most frequent serogroup was the B (73%) followed by C and A. A high heterogeneousness of the antigenic formulae was observed The most frequent phenotype was NT: NST for the group B isolates and 4:P1.13 for the group C ones. N meningitidis with reduced susceptibility to penicillin and to amoxicillin account for 54% and 10% of all isolates respectively. The cefotaxim and the rifampin were uniformly active.

Etude de la sensibilite aux antibiotiques et des genes de resistance aux macrolides de streptococcus pneumoniae isole en milieu pediatrique tunisien

L'emergence de souches resistantes pose des problemes therapeutiques.Le but de cette etude etait de preciser : les caracteristiques epidemiologiques des souches de S. pneumoniae isolees chez l'enfant; leur sensibilite aux antibiotiques et les genes de resistance aux macrolides. L'etude a porte sur 422 souches non repetitives de S. pneumoniae isolees de 2000 a 2008. Les souches invasives (43;3) provenaient essentiellement de LCR (50;2) et d'hemocultures (34;4); la majorite des souches non invasives (56;6) de prelevements pulmonaires (76;5). Le pneumocoque de sensibilite diminuee a la penicilline G (PSDP) representait 53;3des souches (n=225) et 12;8avaient une resistance de haut niveau.29;6avaient une sensibilite diminuee a l'amoxicilline et 15;1au cefotaxime. 60;6des souches etaient resistantes a l'erythromycine et 59;6a la lincomycine. L'etude parPCR des genes de resistance a montre que parmi les 66 souches testees; 62 hebergeaient le gene ermB; 3 le gene mefA et une souche les 2 genes. Les PSDP etaient beaucoup plus resistants aux differents antibiotiques testes que les pneumocoques sensibles a la penicilline; ceci complique la prise en charge therapeutique de ces infections et justifie leur prevention par l'utilisation d'un vaccin anti-pneumococcique efficace

[Malignant pertussis: an underdiagnosed illness]. / La coqueluche maligne: une maladie sous diagnostiquée.

PURPOSE: Malignant pertussis is a rare life-threatening illness characterized by severe respiratory failure, severe leukocytosis, and pulmonary hypertension. The purpose of this study was to determine the prevalence of malignant pertussis in infants admitted to a pediatric intensive care unit (PICU) for severe acute respiratory failure associated with severe leukocytosis. METHODS: This retrospective study was based on review of the medical charts of infants aged less than 3 months admitted to the PICU between 2006 and 2008 for severe acute respiratory failure requiring mechanical ventilation with leukocytosis greater than 50,000/mm3. Clinical and laboratory data were collected. Polymerase chain reaction (PCR) for detection of Bordetella pertussis was performed on nasopharyngeal washes (NPW) stored at -70 degrees C. RESULTS: Ten patients meeting inclusion criteria were identified. Median age was 2.1 months (range, 0.6 - 3). None of the infants had been vaccinated against pertussis. Although PCR for pertussis was positive in all ten cases, presumptive diagnosis was made in only 3 patients during hospitalization. Nine patients died within a mean of 4.7 +/- 3.3 days after admission. The cause of death was refractory shock and hypoxemia in all cases. Only one patient survived. CONCLUSION: Malignant pertussis is a severe disease that is almost always fatal. It was underdiagnosed in our PICU. Use of PCR for detection of B. pertussis, i.e., the reference method, should be promoted in developing countries.

[Use of the rapid antigen detection test in group A streptococci pharyngitis diagnosis in Tunis, Tunisia]. / Utilisation d'un test de diagnostic rapide des angines à streptocoque bêta-hémolytique du groupe A, auprès d'un échantillon d'enfants à Tunis, Tunisie.

The aims of this study were to determine the contribution of commercial rapid antigen detection test (RADT) in the rapid diagnosis of pharyngitis caused by group A streptococci. A total of 292 children with pharyngitis was included. A duplicate throat swabs was taken simultaneously from each patient. One of them was used for RADT achievement and the other for culture. When cultures were positive, a semi-quantitative evaluation was done. Throat culture and RADT were positive in 59 and 72 cases respectively. Fifty four specimens were positive simultaneously with RADT and culture and 215 specimens were negative using both methods. Eighteen specimens were positive only with RADT, 5 of them were treated by amoxicillin. Regarding to the group of patients with a negative RADT and a positive culture (5 cases), all of them had a culture evaluation at "+" or "++". Specificity and sensibility of the RADT were 92.2% and 91.5% respectively. RADT use by physicians can reduce antibiotic prescription among paediatric population. Because of the high specificity of RADT, therapeutic decisions can be made on the basis of a positive test.

[Beta lactam resistance and molecular markers of 157 Haemophilus influenzae isolates from infants in Tunis]. / Etude de la résistance aux beta-lactamines et des marqueurs moléculaires chez 157 souches d'Haemophilus influenzae isolées chez l'enfant à Tunis.

The aim of this study was to precise the capsular type of Haemophilus influenzae, to determine its susceptibility to beta-lactam agents, and to search for an eventual clonality between the clinical strains of the pathogen. Polymerase chain reaction was carried out to confirm the capsular type and to determine the beta-lactamase type. Minimum inhibitory concentrations (MICs) of beta-lactam agents for H. influenzae were determined by the agar dilution method on Haemophilus test medium, and the strains were analyzed by pulsed-field gel electrophoresis after SmaI restriction. Among 157 strains of H. influenzae studied, 12.1% was of serotype b. Sixty-seven strains (42.7%) were resistant to amoxicillin, among which 51 were resistant through production of TEM-type beta-lactamase while 16 showed high MICs for amoxicillin, amoxicillin + clavulanic acid, and cefuroxim, which suggested a resistance by modification of penicillin-binding proteins. Among the latter strains, five were producing TEM-type beta-lactamase. Cefotaxim, cefixim, and cefpodoxim had low MICs in all cases. The pulsed-field gel electrophoresis revealed 110 pulsotypes. All H. influenzae strains, including noncapsulated strains and serotype-b encapsulated strains, had a high level of heterogeneity, with diversity indices of respectively 0.67 and 0.94.

[Antimicrobial susceptibility and serotype distribution of streptococcus pneumoniae isolates in children in Tunis]. / Sensibilité aux antibiotiques et distribution des sérotypes des souches de Streptococcus pneumoniae isolées chez l'enfant à Tunis.

Streptococcus pneumoniae is a major causative agent of severe infectious diseases. More than 90 pneumococcal serotypes are known, although most invasive and noninvasive diseases are associated with a much smaller number of serotypes. The aim of this study was to determine the antimicrobial susceptibility of S. pneumoniae isolates in children, the distribution of serogroups and serotypes, and the coverage by the serotypes included in the seven-valent pneumococcal conjugate vaccine toward pneumococcal disease. This study investigated 210 nonrepetitive isolates of S. pneumoniae isolated between 1998 and 2004. Antimicrobial susceptibility was tested using the disk diffusion method as determined by the CA-SFM guidelines. Penicillin susceptibility was determined using the oxacillin 5-microg disk screening test. The MICs of penicillin G, amoxicillin, and cefotaxime were determined using the E-test (ABBIODISK). Serotype was determined using rapid latex agglutination (Pneumotest Latex) and the capsular reaction test used antisera from the Staten Serum Institute. The evaluation of susceptibility to ss-lactamins showed that 52.8% of the strains were penicillin non susceptible strains (PNSs), 16.6% had decreased susceptibility to amoxicillin, and 8.5% to cefotaxime. Among noninvasive isolates, 55.2% were PNSs and 50.4% were invasive PNSs. The PNS strains were more frequently resistant to other antibiotics, with 68.4% resistance to erythromycin, 44.1% to trimethoprim-sulfamethoxazole, and 9.9% to chloramphenicol versus 32.3, 11.1, and 1%, respectively, in penicillin-susceptible strains. The predominant serogroups/serotypes of our study were 14 (22%), 23 (14.3%), 19 (11.9%), and 4 (8.5%). The study of the vaccine serotype distribution showed that the theoretical vaccinal coverage of the seven valent vaccines was 62.8% for all the isolates, 55.2% for the invasive isolates, and 67.9% for the PNSs.