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Objectives: To determine the in vitro susceptibility to 18 antibiotics of human strains of Francisella tularensis isolated in France between 2006 and 2016, to check the absence of acquired resistance and to evaluate potential therapeutic alternatives., Methods: Fifty-nine clinically unrelated F. tularensis subsp. holarctica strains identified at the French National Reference Centre for Francisella as belonging to the phylogenetic subclade B.FTNF002-00 were used. MICs were determined in CAMHB medium supplemented with 2% PolyViteX®, using the CLSI broth microdilution method., Results: All strains were susceptible to fluoroquinolones (ofloxacin, ciprofloxacin, levofloxacin and moxifloxacin; MIC range: 0.016-0.25 mg/L), aminoglycosides (gentamicin and tobramycin; MIC range: ≤0.03-0.25 mg/L), doxycycline (MIC range: 0.125-0.25 mg/L) and chloramphenicol (MIC range: 0.5-2 mg/L). The erythromycin MIC range (0.5-2 mg/L) confirmed that all isolates belonged to biovar I of F. tularensis subsp. holarctica. Azithromycin and telithromycin displayed lower MIC ranges (0.25-1 and 0.03-0.5 mg/L, respectively). The tigecycline MIC range (0.25-1 mg/L) was slightly higher than that of doxycycline. All strains were resistant to ampicillin, meropenem, daptomycin, clindamycin and linezolid., Conclusions: F. tularensis strains isolated in France remain susceptible to antibiotic classes recommended for tularaemia treatment. Because fluoroquinolones display the lowest MIC90, have bactericidal activity and have lower therapeutic failure rates compared with doxycycline, they may be advocated as first-line treatment of mild cases of tularaemia, predominant in Europe. MIC data also indicate that azithromycin or telithromycin may be possible therapeutic options against biovar I strains from Western Europe in case of contraindication to first-line antibiotics.

Background: The percentage of strains of Propionibacterium acnes resistant to antibiotics in acne is increasing in many countries, raising the question of the risks associated with bacterial resistance. Numerous series of cases have been published on European populations of acne patients, but at the moment we still have very few data regarding France., Objectives: The aim of this study was to evaluate the prevalence of P. acnes resistant strains to erythromycin, tetracycline, and doxycycline in a population of French acne patients., Methods: Specimens were collected from 273 patients in 43 centers located throughout France (12 hospitals and 31 private office practices)., Results: 75.1% of the patients were carriers of P. acnes strains resistant to erythromycin and 9.5% to tetracycline. One hundred percent of strains resistant to tetracycline were also resistant to doxycycline. There was no significant difference among the regions and between patients followed in hospital or private office., Conclusions: It clearly appears that the percentage of patients with P. acnes strains resistant to erythromycin is similar to that in other countries, but lower for tetracycline or doxycycline in comparison to other European countries.

Doxycyclin is a semi-synthetic structural isomer of the tetracycline family. It exhibits good intra-cellular penetration, with bacteriostatic activity on many bacteria. Different types or bacterial resistance are known. Acquired resistance has a ribosomal or a plasmidic mechanism. Resistance of Propionibacterium acnes is secondary to a mutation of ARNr. Doxycyclin also has an anti-inflammatory activity, via numerous pathways. Doxycyclin is rapidly and almost completely absorbed by the digestive tract. Food has no incidence on the absorption. It has a high but labile affinity for proteins with 90 p. 100 of the molecule linked. It rapidly diffuses in the extravascular compartment and in most of the tissues. Bile excretion is the main excretion route. It occurs more slowly by the kidney with tubular reabsorption. The main dermatological indication is acne with daily dose varing between 50 mg and 100 mg. Although good assays are lacking, a large professional consensus has validated its use. It is also active at the same dosage in rosacea. Chlamydial and mycoplasma urethritis may be treated by doxycyclin, and this antibiotic is presently used as second choice. Many other diseases may be treated as a primary or secondary choice, such as treponematoses, brucellosis, pasteurellosis, borreliosis, rickettsioses and cholera. Some non infectious diseases have been occasionally treated by doxycycline. Digestive side effects are the more frequent. Esophageal toxicity has been reduced with tablets and sufficient concomitant water ingestion. Phototoxicity is dose-dependent. Various cutaneous side effects have been described, some of them severe. Systemic toxicity is rare. Pregnancy is a contra-indication, and as other tetracyclines, it should not be given to children and during lactation. Doxycycline is commercialized as tablets. No reduction of the dose is necessary in renal failure. Association with retinoids is not recommended. Anticoagulants are potentialized. Didanosin, iron, and mineral salts lower its activity.

Minimum inhibitory concentrations of doxycycline and oxytetracycline were determined against 55 Pasteurella multocida strains, 59 Actinobacillus pleuropneumoniae strains and 26 Mycoplasma hyopneumoniae strains isolated from the respiratory tract of pigs. An additional set of 76 P multocida strains isolated from pneumonic pigs was tested for their minimum inhibitory concentrations of doxycycline. The P multocida and A pleuropneumoniae strains were isolated in France and the minimum inhibitory concentrations were determined by an agar dilution method. The M hyopneumoniae strains were isolated in the United Kingdom and minimum inhibitory concentrations were determined by a serial broth dilution method. All the strains tested were susceptible to doxycycline whereas 15 per cent of the P multocida strains and 22 per cent of the A pleuropneumoniae strains were resistant to oxytetracycline. Doxycycline concentrations inhibiting 90 per cent of strains were 1 microgram/ml for P multocida and 2 micrograms/ml for A pleuropneumoniae. The ratio of the minimum inhibitory concentrations of doxycycline and oxytetracycline ranged between 1/1 and 1/4 for the oxytetracycline-susceptible strains and between 1/16 and 1/64 for the oxytetracycline-resistant strains. All the M hyopneumoniae strains were susceptible to doxycycline and oxytetracycline, the concentrations inhibiting 90 per cent of strains being 1 microgram/ml and 2 micrograms/ml, respectively. These data confirm that doxycycline has a higher in vitro activity against pig respiratory pathogens than oxytetracycline.

The in-vitro activities of 19 antimicrobial agents were determined by an agar dilution technique against 300 isolates of the Bacteroides fragilis group, collected from several French hospitals during 1987 and 1988. Results were compared with data determined for strains isolated in 1977. Amongst beta-lactam antibiotics, amoxycillin + clavulanic and imipenem displayed the best activity, although two strains resistant to both amoxycillin clavulanate and imipenem were obtained in the 1987-1988 survey. Chloramphenicol was invariably active against isolates from both periods. Much more resistance to clindamycin was seen in isolates from the more recent survey. Resistance to 5-nitroimidazoles was not observed in isolates from the 1977 survey but was present in a few isolates from the more recent study.