In vitro activities of six new fluoroquinolones against Brucella melitensis.

We have tested the in vitro activities of eight fluoroquinolones against 160 Brucella melitensis strains. The most active was sitafloxacin (MIC at which 90% of the isolates are inhibited [MIC90], 0.12 microg/ml). In decreasing order, the activities (MIC90s) of the rest of the tested fluoroquinolones were as follows: levofloxacin, 0.5 microg/ml; ciprofloxacin, trovafloxacin, and moxifloxacin, 1 microg/ml; and ofloxacin, grepafloxacin, and gatifloxacin, 2 microg/ml.

Comparative evaluation of selective and nonselective media for primary isolation of Helicobacter pylori from gastric biopsies.

BACKGROUND: In this study, we compared and evaluated the efficacy of five culture media for the primary isolation of Helicobacter pylori from gastric biopsies. MATERIALS AND METHODS: A total of 1,174 biopsies (antrum and corpus) taken from 587 patients were plated in parallel on two selective media--Skirrow's medium and brain-heart infusion (BHI) agar supplemented with 10% sheep blood, polymyxin B, vancomycin, trimethoprim, and amphotericin B (HPA medium), and on three nonselective media--chocolate agar with Isovitalex, Columbia blood agar, and BHI-10% sheep blood agar. RESULTS: An isolation rate of 57.9% (680 of 1,174) was obtained with a combination of all media. HPA medium gave the highest isolation rate, 99.4% (676 of 680). Chocolate agar, Columbia blood agar, brain-heart blood agar, and Skirrow's medium showed very poor performance (23.5%, 28.5%, 65.9%, and 71% of all isolates, respectively). The number of cultures in HPA medium discarded due to contamination was only 2 (0.32%). There was no difference in the positive rate of culture in HPA medium between the antrum and the corpus of the stomach. CONCLUSIONS: The HPA medium is superior to Skirrow's medium and nonselective media in promoting growth of H. pylori and, on the basis of these results, we recommended the use of HPA medium for primary isolation of H. pylori from gastric biopsies.

In vitro activity of fosfomycin trometamol against pathogens from urinary tract infections: a Spanish multicenter study.

The in-vitro susceptibilities of a total of 1371 urinary tract pathogens to fosfomycin trometamol were determined. According to the NCCLS breakpoints, Enterobacteriaceae and gram-positive microorganisms were, in general, very sensitive to this antimicrobial. More than 90.0% of the Escherichia coli and Citrobacter spp. and more than 70.0% of the Klebsiella pneumoniae, K. oxytoca, Enterobacter spp., Proteus mirabilis, Staphylococcus aureus, coagulase-negative staphylococci and Enterococcus spp. strains tested were susceptible to fosfomycin trometamol. However, Pseudomonas aeruginosa and Acinetobacter spp. strains were more resistant. In general, recent clinical isolates from urinary tract infections (UTIs) in both community and hospital were also very sensitive (> 80.0%) to fosfomycin, its activity being higher than that of the rest of the antimicrobials commonly used for therapy of uncomplicated UTIs. More than 75.0% of the most frequently isolated pathogens from UTIs, except for P. aeruginosa (31.8%) and Acinetobacter spp. (11.1%), were susceptible to fosfomycin trometamol. The results obtained in this study, together with the infrequency of side effects and its pharmacokinetic properties, indicate that fosfomycin trometamol may be a useful alternative for single-dose therapy of uncomplicated UTIs.

In vitro activity of meropenem against ciprofloxacin-resistant enterobacteriaceae and Pseudomonas aeruginosa.

The in-vitro susceptibilities of a total of 174 ciprofloxacin-resistant Enterobacteriaceae and Pseudomonas aeruginosa were determined. According to the BSAC and NCCLS breakpoints, meropenem, aztreonam, ceftibuten, ceftazidime, imipenem and cefotaxime were the most active (> 90%) antimicrobial agents tested against Enterobacteriaceae. Susceptibility of these strains to piperacillin/tazobactam, cefpodoxime and cefixime (84.96%) was higher than that to tobramycin, gentamicin and fosfomycin (50-75%). More than 90% of P. aeruginosa were susceptible to meropenem when both interpretative susceptibility breakpoint criteria were used. Piperacillin, piperacillin/tazobactam and ceftazidime were active against 50-75% of the same strains. Meropenem was the most active antimicrobial tested against all ciprofloxacin-resistant clinical isolates assayed.

In vitro activity of BAY y 3118, and nine other antimicrobial agents against anaerobic bacteria.

The antibacterial activity of BAY y 3118, a new chlorofluoroquinolone, was determined against 257 strains of anaerobic bacteria and compared with the activities of ofloxacin, ciprofloxacin, sparfloxacin, imipenem, cefoxitin, clindamycin, chloramphenicol, metronidazole, and ornidazole. Overall, BAY y 3118 was the most active agent tested against the Bacteroides fragilis group. Its activity (MIC90, 0.5 mg/L) was 16-fold lower than that of sparfloxacin (MIC90, 8 mg/L), and more than 100-fold lower than that of ofloxacin (MIC90, 64 mg/L) and ciprofloxacin (MIC90, 128 mg/L) against the group. No strains belonging to this group were resistant to metronidazole (MICs range, 0.12-2 mg/L) and ornidazole (MICs range, 0.12-4 mg/L). BAY y 3118 was more active than those quinolones against Prevotella and Porphyromonas spp., Fusobacterium spp., Clostridium perfringens and C. difficile (MIC90, 0.12, 0.06, 0.12 and 0.25 mg/L, respectively). The activity of BAY y 3118 against Peptostreptococcus spp. (MIC90, 1 mg/L) was slightly lower than that of the other Gram-positive bacteria tested. In general, BAY y 3118 was more active than cefoxitin, and it was superior to antianaerobic chemical agents like metronidazole, ornidazole and clindamycin. Pharmacokinetic and clinical trials are required to define the role of BAY y 3118 in the treatment of anaerobic infections.

Activity of BAY y 3118, a novel 4-quinolone, against Brucella melitensis.

We have tested the in-vitro activities of BAY y 3118, a new chlorofluoroquinolone, ciprofloxacin, sparfloxacin, streptomycin, tetracycline and rifampin against 59 strains of Brucella melitensis. BAY y 3118 (MIC90 0.12 mg/L) was twice as active as sparfloxacin and tetracycline (MIC90 0.25 mg/L). The activity of ciprofloxacin, rifampin and streptomycin (MIC90 0.5, 2, and 8 mg/L, respectively) was, respectively, four-, sixteen-, and more than sixty-fold lower than that of BAY y 3118.

Emergence of resistance to imipenem in Enterobacter isolates masquerading as Klebsiella pneumoniae during therapy with imipenem/cilastatin.

Clinical isolates identified as Klebsiella pneumoniae by the Vitek, Enterotube II, and API 20E systems were recovered from a patient undergoing therapy with imipenem/cilastatin. These isolates were resistant to multiple beta-lactam agents, and some were even resistant to imipenem. Analysis revealed a Bush group 1 beta-lactamase, and imipenem resistance corresponded to the loss of outer-membrane proteins in strains expressing high levels of this beta-lactamase. Further characterization efforts yielded abnormal but positive results of tests for ornithine decarboxylase production and motility, and chromosomal homology to an Enterobacter cloacae ampR, ampC probe was detected. These results suggested that the organisms were actually of an Enterobacter species, perhaps Enterobacter aerogenes. Cefoxitin resistance may be a useful marker for preventing this misidentification in the future; misidentification of such organisms poses a hazard, as it may lead to inappropriate beta-lactam therapy for infections caused by organisms that have the potential for resistance due to inducible group 1 cephalosporinases.

Cefdinir: in vitro activity study and effect of human serum.

The in-vitro activity of cefdinir (Cl-983, FK482), an orally absorbed aminothiazole cephalosporin, was compared with that of penicillin, ampicillin, amoxycillin, amoxycillin/clavulanic acid (2/1), cefaclor, cefuroxime, cefixime, cefotaxime, vancomycin and erythromycin against 370 clinical isolates of Gram-negative and Gram-positive bacteria. Cefdinir was highly active against Staphylococcus aureus and S. epidermidis, inhibiting 90% of the strains at doses of 0.25 and 0.5 mg/l respectively. However, cefdinir was not active against methicillin-resistant S. aureus (range 16- > 128 mg/l). The respiratory pathogens Moraxella catarrhalis, Streptococcus pneumoniae, and S. pyogenes were also susceptible (MIC90 < or = 0.5 mg/l), but against Enterococcus spp. cefdinir displayed no useful activity. The common members of the family Enterobacteriaceae were susceptible (MIC90 < or = 1 mg/l), but those possessing chromosomal beta-lactamases were more resistant (MIC90 2-8 mg/l). The presence of human serum had little effect on MICs of cefdinir. These results indicate that cefdinir exhibited a wide spectrum for an oral cephalosporin and support its possible clinical use against susceptible pathogens in infections of the skin, soft tissue, respiratory and urinary tracts.