Over the course of a 20-month period, in a hospital respiratory ward in which ciprofloxacin was often used as empirical antimicrobial therapy for lower respiratory tract infections (LRTIs), 16 patients with chronic bronchitis developed nosocomial LRTIs caused by penicillin- and ciprofloxacin-resistant Streptococcus pneumoniae (serotype 23 F). The minimum inhibitory concentration (MIC) of ciprofloxacin for all isolates from the first 9 patients was 4 microg/mL, in association with a parC mutation. Isolates from the subsequent 7 patients all had a ciprofloxacin MIC of 16 microg/mL, in association with an additional mutation in gyrA. The MICs for this isolate were 8 microg/mL of levofloxacin (resistant), 2 microg/mL of moxifloxacin and gatifloxacin (intermediately resistant), and 0.12 microg/mL of gemifloxacin. This outbreak demonstrates the ability of S. pneumoniae to acquire multiple mutations that result in increasing levels of resistance to the fluoroquinolones and to be transmitted from person to person.

Stenotrophomonas maltophilia is an important emerging pathogen causing a variety of infections in severely ill patients. This microorganism is inherently resistant to many antibiotics, and only a few therapeutic options are available. The principal aim of this study was to assess the in vitro activity of new quinolones against this pathogen. Three hundred and twenty-six single clinical isolates were tested in this study. The MIC(90) was 16 mg/L for ciprofloxacin, 8 mg/L for levofloxacin and gatifloxacin, 4 mg/L for trovafloxacin, moxifloxacin and sparfloxacin and 2 mg/L for clinafloxacin. At a 2 mg/L concentration, a C(max) lung:MIC ratio of >/=10 can be reached for 95%, 84.3%, 83.1% and 81.5% of isolates, respectively, for clinafloxacin, trovafloxacin, moxifloxacin and sparfloxacin (P < 0. 001 compared with levofloxacin and ciprofloxacin). In spite of the rare but serious adverse events associated with the new-generation quinolones, these agents may become very useful in the treatment of certain severe or life-threatening infectious conditions due to S. maltophilia, notably lower respiratory tract infections.

We compared the germ tube test for the direct identification of Candida albicans from positive blood culture bottles, with results obtained from subcultured colonies. The direct germ tube test was 87.1% sensitive and 100% specific for the identification of C. albicans when the results obtained from fungal colonies were compared.Recent evidence has suggested that early institution of appropriate antifungal therapy is a critical factor in improving outcomes during bloodstream infections with Candida species (2, 4, 5). Given that most bloodstream isolates of C. albicans remain susceptible to azoles such as fluconazole (7, 9), the rapid identification of C. albicans is a key step in the diagnostic and treatment algorithm for bloodstream Candida infection to guide targeted and cost-effective antifungal strategy (6).Traditionally, the preliminary identification of C. albicans is made through the use of a germ tube test (GTT) performed on a subcultured colony grown on solid agar. Although the test itself is rapid, growth of sufficient colonies on solid agar requires a delay of a minimum of 24 h and up to 72 h before identification can be performed. In a preliminary report, Terlecka et al. performed the GTT directly from 31 BacTAlert blood culture bottles positive for yeast on Gram stain, thirteen of which were C. albicans (10). Although the numbers were limited, they observed 100% concordance between the direct GTT and a GTT performed with subcultured organisms grown on solid medium. We report here a 2-year prospective study from two sites investigating the possibility that the GTT could be performed directly from blood culture bottles that had been flagged positive. In addition, to extend these results, 67 yeast isolates previously recovered from candidemic patients were tested in blood culture bottles inoculated with human blood.Over a 2-year period, all positive blood cultures in which yeast were visualized by Gram staining were identified at two large teaching hospitals in Montreal, Canada. To maximize strain diversity, only the first positive blood culture was tested for each episode of fungemia. At Maisonneuve-Rosemont Hospital, all blood cultures were inoculated into BacTAlert blood culture bottles (bioMérieux, Inc., Marcy l'Etoile, France), while the Bactec system (BD Diagnostics, Oakville, Ontario, Canada) was used at the Royal Victoria Hospital. All positive cultures were subcultured on Sabouraud dextrose agar, and a direct GTT performed. To perform the direct GTT, 10 to 20 l of the blood culture bottle contents was removed and incubated with 0.5 of rabbit serum for 3 h at 37°C. The presence or absence of germ tubes was recorded. When sufficient growth was obtained on solid agar, a standard GTT was performed by inoculating 0.5 ml of citrated rabbit serum with a loopful of the test strain, followed by incubation at 37°C for 3 h. All isolates were then completely identified using the API20C AUX, the Vitek YBC (bioMérieux), or the Auxacolor 2 (Bio-Rad, Marnes-la Coquette, France) system.To complement these data,...

The in vitro activities of voriconazole, posaconazole, ravuconazole and micafungin were compared with those of fluconazole, itraconazole, ketoconazole, flucytosine and amphotericin B against 164 candidaemia isolates recovered from cancer patients in two Canadian centres. The MIC(50) results for ravuconazole, voriconazole, posaconazole and micafungin were 0.01, 0.03, 0.12 and 0.25 mg/L, respectively. The new antifungal agents showed substantial activity against isolates demonstrating in vitro resistance to fluconazole and itraconazole. These results suggest that the newer antifungal agents possess promising activity against invasive Candida isolates, particularly against those with reduced susceptibility to fluconazole and itraconazole.

Resistance to macrolides among group A streptococci is an increasing problem worldwide. We examined 496 strains phenotypically and genotypically for resistance to erythromycin and clindamycin. Strains were isolated in five different geographical areas representing about 45% of the total Quebec population. The overall resistance rate was 4.6% but varied from 0% in rural areas to 9.4% in Montreal. Of the 23 strains showing resistance to erythromycin, 15 (65%) had an identical pulsed-field gel electrophoresis pattern, were of serotype M28T28 and harboured the erm(TR) gene, suggesting the spread of a single clone. Of the remaining eight strains, two strains had the erm(B) gene, five had the mef gene and one with a different serotype also had the erm(TR) gene.

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Increasing resistance of Streptococcus pneumoniae to macrolides represents a challenge for clinicians. New ketolides have an enhanced activity against macrolide-resistant strains. Four hundred and seventy-four strains of S. pneumoniae were collected during the 2000-2001 season in Quebec through a surveillance network. Macrolide resistance was 20.2%, and significantly higher in non-invasive strains versus invasive ones (22.4% versus 14.8%), and in children (30%) versus adults (14.8%). For susceptible strains, MIC(90)s of ABT-773 and telithromycin were 0.008 and 0.015 mg/L. Among the 96 macrolide-resistant strains, 56 (58%) were erm(B), 35 (37%) carried the mef(A) gene, four were carrying both genes and one none. ABT-773 and telithromycin were very active against all these resistant strains irrespective of the resistance mechanism, with MIC(90)s of 0.25 and 0.5 mg/L, respectively.

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