Potential of Marine Strains of Pseudoalteromonas to Improve Resistance of Juvenile Sea Bass to Pathogens and Limit Biofilm Development

The European sea bass (Dicentrarchus labrax), one of the most produced marine fish species in Europe, is acutely vulnerable to multiple infectious hazards. In this study, we investigated the potential probiotic effect of some marine Pseudoalteromonas bacterial strains against two major pathogens of this species, Vibrio harveyi and the nervous necrosis virus (NNV), and examined their antibiofilm effect. Impregnation phase was done by repeated immersion of juvenile's sea bass during 8 to 12 weeks in seawater containing the probiotic candidates at a concentration of 106 CFU/mL. Four candidates were tested: (1) a combination of two strains producing antimicrobial compounds, hCg-42 and hOe-125; (2) strain 3J6, with known antibiofilm properties; (3) strain RA15, from the same genus, but with no identified probiotic effect; and (4) a control group without probiotics. At the end of the impregnation phase, fish underwent an infection challenge with V. harveyi or with a pathogenic strain of NNV and mortality was monitored. For the V. harveyi challenge, improved survival rates of 10 and 25% were obtained for the RA15 and the mix hCg-42 + hOe-125-impregnated groups, respectively. For the NNV challenge, no significant benefic effect of the probiotics on infection kinetics or cumulative mortality was observed. At the end of the impregnation phase, the maximal thickness of biofilm was significantly lower in the 3J6, double strain, and RA15 groups, compared with the non-impregnated control group. This study highlights the interesting probiotic potential of marine bacteria to limit mortalities induced by bacterial pathogens as well as biofilm development.

Cutaneous ulcers revealing diphtheria: A re-emerging disease imported from Indian Ocean countries?

INTRODUCTION

Diphtheria due to Corynebacteriumdiphtheriae (C. diphtheriae) has become rare in developed countries. In France only 10 cases of toxigenic diphtheria have been reported since 1989, in all cases causing pharyngitis and all emanating from endemic countries with exception of one contact case. We report herein 13 cases with cutaneous diphtheria, in 5 of which diphtheria toxin was produced, and all imported into France between 2015 and 2018.

OBSERVATIONS

Thirteen patients aged 4 to 77 years presented painful and rapidly progressive round ulcerations of the legs, that were superficial and in some cases purulent, with an erythematous-purple border covered with greyish membrane. Bacteriological sampling of ulcers revealed the presence of C. diphtheriae. Only 6 patients had been properly immunized over the preceding 5 years.

DISCUSSION

These cases underline the resurgence of cutaneous diphtheria and the circulation of toxigenic strains in France following importation from Indian Ocean countries. This may constitute an important reservoir for ongoing transmission of the disease. Re-emergence of this pathogen stems from the current migratory flow and decreased adult booster coverage.

CONCLUSION

Cutaneous diphtheria should be considered in cases of rapidly developing painful skin ulcers with greyish membrane, especially among patients returning from endemic areas, regardless of their vaccination status. The clinician should order specific screening for C. diphtheriae from the bacteriologist, since with routine swabbing Corynebacteriaceae may be reported simply as normal skin flora. Vaccination protects against toxigenic manifestations but not against actual bacterial infection. Early recognition and treatment of cutaneous diphtheria and up-to-date vaccination are mandatory to avoid further transmission and spread of both cutaneous and pharyngeal diphtheria.

[Should we consider a complementary treatment after a renal colic drained by an ureteral stent?]

PURPOSE

The aim of the study was to evaluate if only ureteral stent removing after complicated renal colic (RC) could prevent from complementary treatment (shock-wawe lithortripsy or ureteroscopy).

PATIENTS AND METHODS

Data from 95 patients, 39 women and 56 men, who had an ureteral stent for complicated RC from 2005 to 2010 were retrospectively collected. Mean age was 46.4 ± 17.2 years. After the initial management, another hospitalization was organized where patients had ureteral stent removing under local anesthesia, then an abdominal CT-scan without injection and complementary treatment of ureteral stones (none or ESWL or ureteroscopy). Parameters studied were age, sex, stone size, location of calcul. Quantitative values were compared with Student's t test. Qualitative values were compared with the Chi(2). P<0.05 was considered statistically significant.

RESULTS

Mean duration between the two hospitalizations were 1.58 ± 1.84 months. Sixty-one patients (64.2%) had no more urolithiasis. In these patients, mean size of urolithiasis was 5.85 ± 2.33 mm. Location of urolithiasis in distal, mild and proximal ureter was 77%, 3% and 20% respectively. Thirty-four patients (35.8%) had persistant lithiasis after CT-scan. Location of stone in distal, mild and proximal ureter was 17.5%, 5.8% and 76.7% respectively.

CONCLUSION

After management of complicated renal colic by ureteral stent, 64% of patients had spontaneous elimination of stones after removing of ureteral stent, especially in women and pelvic ureter.

Evaluation of the efficacy of a low-passage bovine rotavirus (strain WC3) vaccine in children in Central Africa

The safety and efficacy of a WC3 rotavirus vaccine was evaluated in a double-blind placebo-controlled trial involving 472 children in Bangui (Central African Republic). Each child received two doses of either placebo (235 children) or vaccine (237 children) at a 1-month interval, the first dose being given at 3 months of age. During the follow-up survey 9 months after the first dose, 117 rotavirus diarrhoeas were observed, 59 in the placebo group, 58 in the vaccinated group. The only positive effect of the vaccine was a significantly higher proportion of mild rotavirus diarrhoeal episodes in the vaccinated group than in the placebo group. Of the children in the vaccinated group, 60% had a positive immune response to WC3 rotavirus when tested by plaque reduction seroneutralization.