Comparison of traditional and molecular methods for typing nontoxigenic strains ofCorynebacterium diphtheriae

Thirty-eight nontoxigenic strains ofCorynebacterium diphtheriae isolated between 1987 and 1992 from clinical specimens of French patients were typed by biotyping, antibiograms, bacteriophage typing, ribotyping, and restriction analysis by pulsed-field gel electrophoresis (PFGE). Excellent correlation occurred between the genotypes defined by PFGESfil profiles or by ribotypeBstEll profiles. Genotyping revealed seven genotype patterns among the 26 biotype mitis isolates, five among the nine biotype gravis isolates, and three among the three biotype belfanti isolates. Phage typing was nonreactive for nine of the 38 isolates. A combination of all the typing methods led to the identification of 19 different types ofCorynebacterium diphtheriae.     

Experimental evaluation of the biliary tract passage of ceftriaxone and its hepatic disposition

The biliary elimination of ceftriaxone was studied by an isolated perfused rabbit liver model (n = 5). After adding of 10 mg of this antibiotic to the circulating blood of this preparation, a mean biliary peak level reaching 120.5 +/- 24.6 micrograms/ml was obtained between the 30th and 60th minutes. The total amount of ceftriaxone eliminated unchanged in the bile collected during a 3h period represents 8.8 +/- 2.6% of the administered dose. At the end of this study period, 32.7 +/- 3.3% of the initial dose remained in the circulating blood. The hepatic tissue concentrated 3.7% of the whole dose. At last, control experiments proved that 36.4% of the added antibiotic has been degraded by the experimental system itself. Thus the remaining 18.4% can be attributed to a hepatic biotransformation of ceftriaxone.     

Antibiotic-impregnated plaster of Paris beads. Trials with teicoplanin.

Teicoplanin-impregnated plaster of Paris beads were made and in vitro release properties were studied. Teicoplanin was released in an initial massive dose, with a rapid decline during the first three days, followed by a slowly declining prolonged release up to 30 days. The release tested by diffusion in gelose and high-performance liquid chromatography was found to be 21.4% and 28.2%, respectively, of the amount theoretically present in the beads. Plaster of Paris is a resorbable, nontoxic biomaterial that has already been used to fill dead spaces in bone and deliver antibiotics in the treatment of chronic osteomyelitis. The addition of teicoplanin, a new antistaphylococcal agent with low known bacterial resistance, is a promising alternative. Follow-up tests in vivo, simulating local conditions of the osteomyelitic bone, are necessary to prove efficacy.     

Southern blot detection of human papillomaviruses (HPVs) DNA sequences in gingival tissues.

The highly sensitive and specific methods of molecular biology emphasize the frequency of subclinical infections in the genital tract tissues by the human papillomaviruses (HPVs). The purpose of this work was to investigate occult viral infections by the HPV type 6, 11, 16, and 18 in the gingival tissues. The Southern blot method with 32P-radiolabeled DNA probes applied under stringent conditions to 20 interproximal gingival papilla specimens revealed homologous viral sequences in 1 of 6 cases of adult periodontitis (HPV 16), 1 of 2 cases of rapidly progressive periodontitis (RPP) (HPV 6/HPV 11), 2 of 2 cases of acute gingivitis in psychiatric institutionalized patients (HPV 6; HPV 6/HPV 11), and 2 of 10 cases of acute gingivitis in AIDS patients (HPV 6/HPV 11/HPV 16; HPV 6). No periodontal or extra-periodontal specimen hybridized with the HPV 18 probe. Simultaneous hybridization with two or three HPV types was common (3/6 cases). The present detection of HPV 6, 11, 16 DNAs or related-DNAs in periodontal tissues without obvious clinical signs of viral infection suggests that the gingival epithelium may act as a reservoir.     

Effect of prolonged inhibition of neutral endopeptidase on cardiac hypertrophy in rats with myocardial infarction

Summary Myocardial infarction was induced in rats by ligation of the left coronary artery. Treatment with TM1, a prodrug of SQ 28,603, an inhibitor of neutral endopeptidase (NEP, EC 3.4.24.11), was started 18–20 hours after ligation and was continued for 4 weeks (100 mg/kg, orally, twice daily). Morphological and biochemical parameters were assessed at the end of therapy. The treatment resulted in a significant reduction of heart hypertrophy, which was restricted to the parts of myocardium hemodynamically upstream of the infarcted left ventricle. The weights of the right ventricle and atria were reduced by 15–20%, whereas the treatment had no effect on the left ventricle and septum weights. Treatment led to an almost complete inhibition of plasma NEP activity and to a slight decrease (-14%, p<0.05) in plasma ACE activity. Plasma ANF level increased 3.8-fold after ligation, and treatment resulted in a slight (+29%) and nonsignificant additional increase in the ANF level. The amount of hydroxyproline in the right ventricle was enhanced by +207% in control ligated rats and by +140% (NS) in treated rats. These data indicate that prolonged NEP inhibition exerts a favorable effect in heart failure by reducing the development of right ventricular and atrial hypertrophy. These effects may result from an improvement in hemodynamic conditions, leading to a reduction in cardiac preload.     

Virulence factors of clinical Aeromonas caviae isolates

Aeromonas caviae, an ubiquitous aquatic organism, has long been considered to be of low pathogenicity, and its virulence mechanisms are still not clearly understood. Twenty-eight A. caviae isolates of clinical origin, most often monomicrobic, were identified in our university hospital over a four year period. Patients, mostly immunocompromised, were: eight diarrhoeal infants, 13 diarrhoeal adults, seven bacteraemic adults. Adults were frequently suffering from underlying intestinal malignancy, hepatobiliary disease, gastrectomy. Virulence factors were investigated. Adherence, studied by use of tissue culture HEp-2 cells, and staining of characteristic lateral flagella, were observed in diarrhoeal strains. Extracellular hemolytic activity was tested on rabbit erythrocytes suspensions at 25 and 37 degrees C. One blood culture isolate showed an important hemolytic activity at 25 degrees C, but none at 37 degrees C. Treatment with furin activated the aerolysin precursor and resulted in significant hemolysis at 37 degrees C, and fluid accumulation in rabbit ileal loops similar to that of A. hydrophila as control. The presence of the hemolysin gene was confirmed in this strain by PCR. In conclusion, A. caviae was shown to be a pathogen isolated from diarrhoea and bacteraemia in immunocompromised patients with malignancies and low gastric acidity as favouring factors. Virulence including the ability to adhere to cells and the production of lateral flagella was observed in diarrhoeal strains. The expression and the production of extracellular hemolytic activity and enterotoxicity at 37 degrees C depended on the activation of the pore forming toxin aerolysin precursor by furin. In vivo the protoxin is probably processed to its mature form by host proteases.     

Peripartum bacteremias due to Leptotrichia amnionii and Sneathia sanguinegens, rare causes of fever during and after delivery

We report three cases of delivery and postpartum bacteremia due to unusual anaerobic bacteria in healthy young women. Leptotrichia amnionii bacteremia occurred during delivery in two mothers and was associated with fetal distress during labor. Conversely, Sneathia sanguinegens bacteremia occurred postpartum, 2 days after delivery, without consequence for the neonate.     

Isolation of Aeromonas hydrophila in diarrhea. Characterization of enterotoxinogenic strains and clinical relations

Aeromonas hydrophila is isolated from diarrhoea specimens with increasing frequency. The interest in this organism at the present time is related to the fact that it can produce a number of toxins, in particular alpha and beta cytotoxic haemolysins, an enterotoxin and various enzymes. The authors determined the frequency of isolation of this organism and tested the haemolytic, cytotoxic and enterotoxic effects of culture filtrates in all of the stool specimens received in their laboratory over a period of 9 months. At the same time, the clinical context was defined in order to demonstrate a relation between the aptitude of the strains to produce toxins and the presence of diarrhoea. The frequency of isolation of A. hydrophila was 0.88 per cent, which corresponds to 67 strains. 38 strains presented a haemolytic and/or enterotoxic activity, i.e. 57 per cent of the strains isolated. In diarrhoeal stools, 67 per cent of the A. hydrophila isolated produced at least one of the toxins, while in the group of patients without diarrhoea, only 38 per cent of the strains isolated produced toxins. The results obtained reveal a statistically significant correlation between the production of cytotoxic haemolysin and the presence of diarrhoea. In contrast, there was no correlation between the production of enterotoxin and the presence of diarrhoea. Twenty of the 67 strains ware isolated from children under the age of 2 years. In 40 per cent of cases, no other aetiology could be found for the diarrhoea, apart from the isolation of A. hydrophila.(ABSTRACT TRUNCATED AT 250 WORDS)