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 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.

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.

Microbiological profile of haematogenous osteoarticular infections in children

INTRODUCTION

Staphylococcus aureus, Kingella kingae and β-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 β-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.

[Neisseria meningitidis invasive infections in children in Tunis: about 79 cases]

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.

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.

[Malignant pertussis: an underdiagnosed illness]

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]

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.

Étude de la résistance aux β-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 β-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 β-lactamase type. Minimum inhibitory concentrations (MICs) of β-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 β-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 β-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.

Phenotypic and genotypic characterization of macrolide resistant Streptococcus pneumoniae in Tunisia

One hundred of non duplicate Streptococcus pneumoniae resistant to erythromycin collected from three teaching hospitals in Tunisia from January 1998 to December 2004 were investigated to evaluate determine their resistance level to different macrolides and the mechanisms involved. Most erythromycin resistant S. pneumoniae were isolated from respiratory tract (34%). Eighty-three percent showed constitutive MLS(B) phenotype with high MICs of macrolides and lincosamides (MIC90 >256 microg/ml), 12% M phenotype with moderately increased MICs of macrolides (MIC90: 12 microg/ml) and low MICs of lincosamides (MIC90=0.75 microg/ml) and 5% inducible MLS(B) with high MICs of macrolides (MIC90 >256 microg/ml) and moderately increased MICs of lincosamides (MIC90=8 microg/ml). All strains were susceptible to quinupristun-dafopristin association and linezolid (MIC90=1 microg/ml). Strains belonging to MLS(B) phenotype were PCR positive for the erm B gene (88%). Twelve percent categorized as M phenotype carried the mef A gene. The rates of associated resistance were 68% to penicillin G, 53% to tetracyclines, 61% to cotrimoxazole, 21% to chloramphenicol and 13% to ciprofloxacin. MLS(B) constitutive phenotype conferring cross resistance to macrolides, lincosamides and streptogramins B with high level of resistance was the most prevalent. Thus, quinupristin-dalfopristin association and linezolid remain the most active molecules.

[Antimicrobial susceptibility of 80 Moraxella catarrhalis strains isolated in the children's hospital of Tunis]

Eighty non-repetitive strains of Moraxella catarrhalis, isolated in Tunis Children's Hospital during five years from 1998 to 2002, were tested for their antimicrobial susceptibility, 95% of these strains were isolated from lung samples: 57.5% from trachea products, 35% from sputum and 2.5% from bronchial washings. The majority of strains (72%) were obtained from children under two years old. Antimicrobial susceptibility study showed that 95% of stains were beta-lactamase-producing, therefore they were penicillin G and amoxicillin resistant with high MICs. MIC(90) of penicillin G and amoxicillin of beta-lactamase-producing strains were respectively greater than 32 and 6 mg/l, these MIC decrease with addition of clavulanic acid. In fact, all strains studied were susceptible to the association amoxicillin-clavulanic acid as well as to cefotaxime. Concerning the other antimicrobial groups percentages of resistant strains found were as follows: erythromycin 3.75%, trimethoprim-sulfamethoxazol 12.5% and tetracycline 1.25%. Finally, all strains were susceptible to chloramphenicol, rifampicin and ciprofloxacin.

Patterns of resistance to beta-lactams and characterization of beta-lactamases in Escherichia coli isolates from children in Tunisia

Seventy-six (75.2%) of 101 Escherichia coli isolates, collected over a 2-month period in 2002 at the Children's Hospital of Tunis (Tunisia), were resistant to at least one beta-lactam. They produced beta-lactamases which were further characterized by spectrophotometry, isoelectric focusing (IEF) and PCR. Seventy-five isolates had a pI 5.4 beta-lactamase and one isolate expressed a pI 5.6 beta-lactamase. These beta-lactamases were active against penicillins and cephalothin. Nineteen of 76 isolates were resistant to ticarcillin-clavulanic acid combination. The bla(TEM) gene was detected in 71 isolates, all expressed a pI 5.4 beta-lactamase that was assumed to be TEM-1 or inhibitor-resistant TEM (IRT). Thirty-eight of 76 isolates showed one weak band on IEF with pIs ranging from 8.2 to >9, suggesting low level expression of the chromosomal AmpC beta-lactamase. Five of 76 isolates produced extended-spectrum beta-lactamases (ESBLs), with a basic pI of 7.9 or 8.7, active on penicillins, extended-spectrum cephalosporins, but not on cefoxitin. bla(SHV) genes were detected in three isolates producing pI 7.9 ESBLs but not in two isolates expressing pI 8.7 ESBLs. These latter showed strong cefotaxime-hydrolyzing activities. Hence, they might be CTX-M-type ESBLs.

[Study of Haemophilus influenzae strains isolated at the Tunis children's hospital in the prevaccination era (1999-2002)]

OBJECTIVE

This study had for aim to define the pattern of Haemophilus influenzae infections in a Tunisian hospital during the prevaccination era. We determined serotypes, biotypes, and antibiotic susceptibility of H. influenzae strains.

DESIGN

187 H. influenzae strains were identified in various samples between 1999 and 2002.

RESULTS

Strains were isolated essentially from respiratory samples in 63.7% and cerebrospinal fluid in 21.4 %. The mean age of children with invasive infections was 16 months. All invasive strains belong to serotype b. Biotypes I, II and III were the most frequent (84.7%). Ampicillin resistance with betalactamase producing mechanism occurred in 26,7% of isolates, this type of resistance was more frequent among invasive strains (37.2%) than in non-invasive ones (22.8%). All betalactamase producing strains had amoxicillin MICs above 1 mg/l, these strains were susceptible to amoxicillin+clavulanate. Three strains were betalactamase negative ampicillin resistant with ampicillin MICs: 1.5, 3, and 4 mg/l. All strains were susceptible to cefotaxim with MICs < 0.19 mg/l. Antibiotic resistance concerned: chloramphenicol: 7.5%, tetracycline: 6.9% and trimethoprime-sulfamethoxazole: 13.9%. 8.1% of the strains were kanamicin resistant but concerned only betalactamase producing strains.

CONCLUSION

Before the introduction of a conjugate vaccine, all invasive infections in young children were caused by H. influenzae b strains.

[Role of enteroviruses in aseptic meningitis in Tunisia]

Despite the favourable clinical outcome in most cases, viral meningitis can cause a serious public health problem especially when several cases occur during outbreaks. The first part of this work is a retrospective study conducted in three hospitals in Tunisia and covering a period of three years. It showed an incidence of viral meningitis 2.4. The second part of the study is a prospective one, it included 94 cases of aseptic meningitis notified during a period of 12 months. Virus isolation in cell culture was performed on CSF and stool samples, using cell lines sensitive to enteroviruses. A PCR to detect enteroviruses was also used in parallel. This study represents a first approach to viral meningitis in Tunisia. It highlights the importance of a regular surveillance of the disease and the contribution of molecular methods to a more sensitive diagnostic. However, cell culture remained necessary for viral isolation and serotyping.

[Clinical aspects and etiology of lower respiratory tract infections in hospitalized children]

The authors report a prospective study conducted in one of the general pediatrics unit. One hundred one children, aged 20 days to 12 years, admitted with acute lower respiratory tract infections have been studied on clinical paraclinicals and etiology grounds. All children had a chest Ray roentgenogram, a total blood cell count and C-reactive protein. The detection of a viral agent in nasopharyngeal aspirate by immunofluorescent technic were performed. 85% of patients have bronchiolitis, the chest--Rays showed an abnormal pictures in 84.2% of cases, an anaemia was present in 54.7%. Viral agent as identified in 58 patients, the RSV indicated in 56 cases. Bacterial infection as present in 57 of the 101 children. A mixed viral-bacterial infection as documented in 28 cases. Among bacterial causes the predominant agent as Haemophilus influenzae 24, Branhamella Catarrhalis 17, streptococcus pneumoniae in 16 cases. Early empiric antibiotic as performed. All patients recovered uneventfully.

[Prevalence of sexually transmitted diseases among pregnant Tunisian women and validation of a clinical algorithm proposed by WHO for the management of sexually transmitted diseases]

The objectives of our study are to assess the prevalence of STD agents in Tunisia and to validate the WHO algorithm of STD management. The most frequent STD agents are Trichomonas vaginalis and Chlamydiae trachomatis, respectively with a prevalence of 5.6% and 1.7%. The assessment of the syndromic approach shows that the sensitivity and specificity of the WHO algorithm can be improved by the introduction of risk factors. The training of health care service providers and the use of an algorithm including risk factors can improve this approach, which is useful when laboratories services are not available.

[Incidence and management of male urethritis in the district of Tunis]

BACKGROUND

The aim of the study was to evaluate the incidence of male urethritis and the relative frequency of the different etiological agents in order to adapt standard case management.

METHODS

The incidence of urethritis has been estimated with a postal study made on a sample of druggists (1/10) of the area. The total observation period was four weeks. The relative frequency of the etiological agents and the positive predictive value (PPV) of the therapeutic approach based on antibiotic treatment of gonorrhoea and Chlamydia trachomatis was achieved on 92 cases of male urethritis attending general physicians in two polyclinics.

RESULTS

The annual incidence of male urethritis was estimated at 680 per 100,000. The relative frequency of etiological agents was as 34.7% for Neisseria gonorrhoea, 7.6% for Chlamydia trachomatis and was found at 3.3% for Trichomonas vaginalis; the PPV was only 43% because of the high proportion of negative results reported by the laboratory.

CONCLUSION

Gonococcal urethritis incidence tends to decrease regarding non gonococcal urethritis and the therapeutic approach appears to be warranted.

[Lyme disease in Tunisia, results of a clinical and serological study (1992-1996)]

Lyme disease was suspected in 271 patients seeking hospital care between 1992 and 1996. The sera of all these patients were tested by ELISA for antibodies against Borrelia burgdorferi. Twenty-nine cases of Lyme disease were identified, each involving neurological and articular problems. These results demonstrate that Lyme disease occurs in Tunisia and suggest that this diagnosis should be considered more frequently in patients presenting with the characteristic symptoms.

[Septicemia caused by A, B, C and G groups of beta-hemolytic streptococci]

During a five and a half years' period, 805 strains of beta-haemolytic groups A, B, C and G streptococci were isolated. Among these, 28 were responsible for bacteremia; 57 percent group B and 32 percent group A. All strains were susceptible to beta-lactam antibiotics; 4 strains were resistant to macrolides. The majority of patients had underlying diseases. Mortality was high in this group.

[Characteristics of the first penicillinase-producing strains of Neisseria gonorrhoeae isolated in Tunisia]

The first penicillinase-producing strain of Neisseria gonorrhoeae was recently isolated in Tunisia (1989). Betalactamase production was detected by the iodometric agar test. Minimal inhibitory concentrations (MICs) in agar medium were 128 micrograms/ml for penicillin, ampicillin and amoxycillin. With the amoxycillin-clavulanic acid combination, MIC fell to 0.25 microgram/ml. An Asian-type plasmid pattern was evidenced in this strain, with presence of the 2.6 Mdal cryptic plasmid and of a 4.5 Mdal plasmid.

[Group D streptococci and enterococci: identification, sensitivity to antibiotics and a study of the high level resistance to aminosides (Charles Nicolle Hospital in Tunis)]

197 strains of enterococcus and group D Streptococcus were isolated from human material at Charles Nicolle Hospital (Tunis) and identified by biochemical tests: 174, Enterococcus faecalis, 6 Enterococcus faecium, 2 Enterococcus durans and 15 Streptococcus bovis. The sensitivity to antibiotics was studied: all Enterococcus faecium were resistant at least to one antibiotic, 15% of Enterococcus faecalis were sensitive for all antibiotics tested the other species were frequently sensitive. High level resistance to aminoglycosides were frequent in Enterococcus faecalis 40%: among these strains high level resistance to gentamicin accounts for 12% and 18 frequently associated with resistance to kanamycin and streptomycin, this situation present therapeutic problems in case of severe infection.

[Non-groupable streptococci: identification, sensitivity to antibiotics (Charles Nicolle Hospital in Tunis)]

50 strains of viridans streptococci isolated from human material are identified by biochemical tests (bile esculin, Cl Na 6,5%, acid production from lactose, mannitol, sorbitol, inulin, arginine, esculin and starch hydrolysis; production of levan and dextran in sucrose media) Streptococcus salivarius and Streptococcus mitis are predominant species. Susceptibility to antibiotics was studied: 70% of viridans streptococci were susceptible to all antibiotics tested, high level resistance to aminoglycoside was not present. The only resistance observed were to tetracycline, macrolides and related drugs.

[Sensitivity of Neisseria gonorrhoeae to antibiotics]

Since 1976 strains of Neisseria gonorrhoeae producing beta-lactamase have been isolated in many countries. Strains with high level resistance to tetracycline have been also described. The appearance of resistant strains implies a constant surveillance of the isolated gonococcus and the study of their antibiotics sensitivity.

[Enzymatic resistance to cefotaxime in 56 strains of Klebsiella spp., Escherichia coli and Salmonella spp. at a Tunisian hospital (1984-1988)]

The enzymatic and plasmid-encoded resistance towards oxyimino-beta-lactams has been recently reported as related to the production of an extended-spectrum beta-lactamase (e.g. SHV-2, CTX-1 or TEM-3), in particular in our hospital since 1984. The prevalence of that resistance has been examined from January 1984 to December 1988 in function of specimen, unit and type of enzyme among 8,421 isolates of Klebsiella spp., E. coli, Salmonella spp. Each isolate showing a diameter of inhibition zone size inferior or equal to 25 mm for cefotaxime, the double disk synergy test was performed between a disk of amoxicillin and a clavulanic acid disk of cefotaxime, ceftriaxone, ceftazidime and aztreonam. In case of synergy, sonicated extracts have been prepared and examined by isoelectrofocusing with the detection of beta-lactamase activity by ceftriaxone and nitrocefin. 56 isolates (K. pneumoniae, K. oxytoca, E. coli, S. wien, S. typhimurium scored positive including 27 in pediatrics, 18 in surgery, and 8 in medicine. 41% of isolates have been obtained from blood cultures and 26.8% from urines. A majority of isolates (49/56) produced the SHV-2 type, but other types mediating the resistance phenotype CTX have been individualized initially by their isoelectric points e.g. 5.4 (TEM-20 in K. pneumoniae in July 1986), 6.4 (TEM-21 in E. coli, 1 K. pneumoniae in July 1988). The prevalence of resistance to cefotaxime from 1984 to 1988 has increased (from 0.3 to 1.4%), the highest rate being observed in pediatrics (5.6% in 1984 and 22.1% in 1988).