In vitro sensitivity to antibiotics in 178 strains of genital mycoplasma isolated from gynecology consultants in Dakar

The susceptibility to antibiotics of 144 strains of Ureaplasma urealyticum and 34 strains of Mycoplasma hominis isolated in Dakar, Senegal, was determinated by MIC determination in a medium. Doxycyclin and minocyclin are active on more than 90% of the strains of U. urealyticum, and more than 80% of M. hominis strains. Over 93% of U. urealyticum strains are susceptible to all the macrolids and apparented tested (erythromycin, pristinamycin, josamycin), but the activity of lincomycin, pristinamycin and josamycin on M. hominis was found only for 70% of the strains. Fluoroquinolones, once adequately studied, could turn out to be a useful alternative in therapeutics.     

In vitro sensitivity of Chlamydiae to antibiotics

The in vitro activity of 11 antibiotics against 16 Chlamydia trachomatis strains isolated from genital tract and 2 Chlamydia psittaci strains isolated from pulmonary tract. The CMI determination (the lowest dilution of the drug which inhibited the inclusion development when untreated control give 10(3) IFC) was assessed by growth in cycloheximide treated McCoy cells-antibiotics were added after incubation for 2 hours at 37 degrees C. The CMI values for Chlamydia trachomatis and Chlamydia psittaci are similar. The activity of antibiotics by comparison between CMI90 and serial levels. The CMI90 (mg/l) were: doxycycline = 0.2, minocycline = 0.2, roxythromycine = 0.12, érythromycine = 0.5, spiramycine = 4, rifampicine = 0.016, ofloxacine = 4, ciprofloxacine = 4, pefloxacine = 8, lomefloxacine = 8, fleroxacine = 8. For Chlamydia trachomatis species all the strains have the same sensibility, no resistance was detected.     

In vitro sensitivity of Mycobacterium xenopi to five antibiotics

We tested 20 strains of Mycobacterium xenopi (M. xenopi) in order to evaluate their in vitro sensitivity to amikacine, clarithromycine, ethambutol, ofloxacine and rifampicin, by establishing minimal inhibitory concentration (MIC) on agar medium. MICs of amikacine, clarithromycine and ofloxacine are low, so that these antibiotics can be used in the treatment of M. xenopi infections. MICs of ethambutol are higher than seric concentrations. Though, its therapeutic use is due to its in vivo ability to enhance penetration of other antibiotics in mycobacteria. Strain sensitivity to rifampicin seems heterogeneous but the small number of tested strains does not entitle the exclusion of rifampicin from the treatment of M. xenopi infections.     

In vitro activity of new quinolones against Mycoplasma pathogenic to humans

The in vitro activity of new quinolones was evaluated against Mycoplasma pneumoniae (10 strains) and Mycoplasma hominis (approximately equal to 70 strains) by agar dilution, and against Ureaplasma urealyticum (approximately equal to 115 strains) by broth dilution. The static effect of pefloxacin, ofloxacin, ciprofloxacin, enoxacin was investigated for all the strains. Rosoxacin was included in the tests for U. urealyticum and M. hominis. Pefloxacin, ofloxacin, ciprofloxacin and enoxacin were within the same range of sensitivity for M. pneumoniae; the minimal inhibitory concentrations (MICs) of the 10 strains were 1 mg/l for ciprofloxacin, 2 mg/l for pefloxacin, MICs range was (0.05-1 mg/l) for ofloxacin and (0.5-4 mg/l) for enoxacin. Ciprofloxacin was the most active compound against M. hominis; MICs range and mode MICs were respectively in mg/l: (0.1-1) 0.5 for ciprofloxacin, (0.2-2) 0.5 for ofloxacin, (0.5-2) 1 for pefloxacin, (0.5-8) 2 for enoxacin, (2-16) 2 for rosoxacin. Ofloxacin was the most active compound against U. urealyticum; MICs range and mode MICs were respectively in mg/l: (0.2-2) 1 for ofloxacin, (0.1-8) 2 for rosoxacin, (0.5-8) 4 for pefloxacin, (1-16) 4 for ciprofloxacin, (2-32) 8 for enoxacin. No difference could be observed between tetracycline sensitive or resistant strains.     

In vitro activities of new quinolones against Brucella melitensis isolated in a tertiary-care hospital in Turkey

We have evaluated the in vitro activities of seven fluoroquinolones against 69 strains of Brucella melitensis . According to their minimum inhibitory concentration for 90% growth (MIC₉₀) values, the most active agent was found to be sparfloxacin (MIC₉₀ 0.12 mg/L) followed by levofloxacin, ciprofloxacin, ofloxacin (MIC₉₀ 0.50 mg/L) and grepafloxacin (MIC₉₀ 1 mg/L), gemifloxacin (MIC₉₀ 2 mg/L) and gatifloxacin (MIC₉₀ 4 mg/L).     

In vitro sensitivity at 18 antibiotics of 192 strains of Pseudomonas aeruginosa isolated at Garches Hospital

The in vitro activity of 18 antibiotic (beta-lactam agents, quinolones and aminoglycoside has been evaluated against 192 clinical isolates of Pseudomonas aeruginosa. Minimal inhibitor concentrations (MICs) were determined by the agar dilution technique. The 50% and 90% MICs were respectively: ticarcillin (32/greater than 1 024), azlocillin (16/512), piperacillin (8/512), cefsulodin (4/128), ceftazidime (2/8), aztreonam (4/16), imipenem (2/4), nalidixic acid (128/256), pefloxacin (1/8), norfloxacin (1/8), ofloxacin (2/8), ciprofloxacin (0.25/2), gentamicin (8/256), sisomicin (4/256), tobramycin (2/128) dibekacin (4/256), netilmicin (16/256), amikacin (8/16). The sensitivity to beta-lactam agents and to quinolones was usual. Resistance to aminoglycosides was frequently observed (59%): 35.7% of the resistant isolates were resistant to gentamicin-sisomicin-tobramycin-dibekacin-netilmicin, 30% to netilmicin alone, 17.8% to gentamicin-sisomicin-tobramycin-dibekacin-netilmicin-amikacin, 7% to gentamicin-netilmicin, 5.3% to gentamicin-sisomicin-tobramycin-dibekacin; we did not find any P. aeruginosa resistant only to gentamicin or gentamicin-sisomicin.     

In vitro susceptibility of quinolone-resistantCampylobacter jejuni to new macrolide antibiotics

The MICs of erythromycin and three new macrolide antibiotics were determined for 36 quinolone-susceptible and 106 quinolone-resistantCampylobacter jejuni. The MIC90 values of azithromycin, clarithromycin, roxithromycin and erythromycin were 0.5, 4, 16 and 4 mg/l respectively. No difference was found between macrolide activity against the quinolone-susceptible and the quinolone-resistant strains. Clarithromycin and especially azithromycin might eventually replace erythromycin for the treatment ofCampylobacter jejuni infections in view of their pharmacological properties.     

Characteristics of Neisseria gonorrhoeae isolated in Australia showing decreased sensitivity to quinolone antibiotics.

Forty three strains of Neisseria gonorrhoeae with decreased sensitivity to quinolone antibiotics were detected amongst 2141 Australian isolates of gonococci examined in the years 1984 to 1990. The strains examined belonged to 23 different auxotype/serovar classes, were generally more resistant to other antibiotics and, in the majority of cases, were isolated from travellers entering or returning to Australia from SE Asia. Quinolone-sensitive wild-type gonococci became less sensitive to these agents in vitro at a relatively high frequency when grown in the presence of quinolone concentrations at or around the MIC (Mean Inhibitory Concentration) of the antibiotic. Further increments in the levels of quinolone resistance of the already less-sensitive gonococci were also produced by this means, but high-level resistance to these agents was not observed. This suggests that mechanisms other than alterations in the DNA-gyrase of the organisms were responsible for the changes seen. Although spread of quinolone resistance in gonococci in Australia is unlikely to be rapid, if these antibiotics are used in therapy, treatment regimens with higher rather than lower dosages of quinolone antibiotics should be employed.     

In vitro activities of eight antibiotics against methicillin-resistant S. aureus and S. epidermidis strains isolated in Korea

Staphylococcus aureus and Staphylococcus epidermidis strains isolated at eight large medical centers in Korea were examined for methicillin resistance and resistance to eight other antibiotics; cefazolin, cefamandole, cefuroxime, cefoxitin, cefotaxime, moxalactam, penicillin G and vancomycin. Methicillin resistance was found in 296 of 1225 strains (24.2%) of S. aureus and 126 of 348 strains (36.2%) of S. epidermidis. Methicillinresistant strains were isolated from all sources with the frequency of isolation ranging from 11% to 60%. From pleural effusion, throat swab and blood, methicillin-resistant strains of S. aureus were more frequently isolated with statistical significance (Chi-squared test, 95% confidence). Almost all of Methicillin-resistant S. aureus (MRSA) and S. epidermidis (MRSE) strains were multiply resistant to one or more tested eight antibiotics. However only 7(2.4%) of 296 MRSA strains and 2(1.6%) of 126 MRSE strains were resistant to vancomycin. Vancomycin was the most effective antibiotic against staphylococcal isolates as well as MRSA and MRSE.     

In vitro activity of the new ketolide HMR 3004 compared to an azalide and macrolides againstStreptococcus pneumoniae andHaemophilus influenzae

The purpose of this study was to compare the in vitro activity of a new ketolide, HMR 3004 (RU64004), to that of three macrolides and one azalide against 608 Streptococcus pneumoniae and 202 Haemophilus influenzae. Macrolide-resistant pneumococci were susceptible to HMR 3004, even if they were resistant to clindamycin. Against Haemophilus influenzae, HMR 3004 and azithromycin were nearly identical in potency; the macrolides were 8- to 16-fold less active. HMR 3004 may be useful for treating respiratory tract infections if sufficient concentrations can be achieved at the local sites of infection.     

In vitro sensitivity of Candida (Torulopsis) glabrata to clotrimazole

Vulvovaginitis caused by Candida (Torulopsis) glabrata is often refractory to intravaginal imidazole therapy. Clotrimazole achieves its fungistatic activity for Candida albicans and C. glabrata by inhibiting different steps in intermediary cell metabolism. For C. glabrata, alkylation precedes dimethylation. The possibility that this altered sequence might account for the relative therapeutic nonresponsiveness was studied by determining comparative minimal inhibitory concentrations (MICs) of clotrimazole. In vitro analyses of ten strains of C. glabrata and 30 control strains of C. albicans performed using both agar and broth dilution tests revealed that four-fold lower MICs were consistently demonstrable with C. glabrata, irrespective of inoculum size. The data suggest that clinical difficulties encountered in the therapy of torulopsis vulvovaginitis probably represent the inability of intravaginal medication to eradicate urethral/urinary bladder colonization and subsequent reinfection rather than true therapeutic failures.     

In vitro evaluation of the sensitivity to fluconazole of different species of yeasts isolated in pathology]

In a previous study, the authors developed a technique for evaluating the in vitro susceptibility (or resistance) of Candida albicans to fluconazole, using casitone broth and agar. Photometric readings of growth in liquid media proved more accurate for evaluating antifungal activity and consistently agreed with clinical findings in all studied cases. This method was consequently extended from C. albicans to other yeasts recovered from high-risk patients (C. glabrata, C. famata, C. tropicalis, C. krusei, C. pseudotropicalis, C. parapsilosis, etc...). High resolution antifungal assay medium (broth and agar) and casitone medium (broth and agar) with or without agitation (Autobac System) were used to study the activity of fluconazole against approximately one hundred yeast strains. MICs above 3.12 micrograms/ml were found for several strains, particularly belonging to the C. glabrata and C. krusei species. These values are equal to or greater than serum levels achieved during treatment with fluconazole, a fact which raises practical questions concerning fluconazole therapy and may explain the failure of fluconazole to eradicate yeasts in some patients.