In vitro activity of fluoroquinolones against clinical isolates of Nocardia identified by partial 16S rRNA sequencing.

Fluoroquinolones have several properties that make them potentially attractive candidates for the treatment of Nocardia infections, but information regarding their in vitro activity is limited. Minimum inhibitory concentrations (MIC) of five fluoroquinolones and other antimicrobials were determined by the reference broth dilution and E-test methods for 33 consecutive clinical isolates of Nocardia speciated by 16S rRNA gene sequences. The isolates included: Nocardia cyriacigeorgica (n = 6), N. nova (n = 8), N. farcinica (n = 8), N. brasiliensis (n = 3), N. asteroides (n = 4), and N. veterana (n = 4). MIC50/MIC90 results for ciprofloxacin, gatifloxacin, gemifloxacin, levofloxacin, and moxifloxacin by broth dilution were 32/32, 2/4, 1/4, 32/32, and 2/2 microg/ml, respectively. The MICs by broth dilution and E-test were within a two-fold doubling dilution for 94%, 97%, 97%, 100%, and 100% of isolates for ciprofloxacin, gatifloxacin, gemifloxacin, levofloxacin, and moxifloxacin, respectively. For ciprofloxacin, the E-test results showed either complete categorical agreement or minor error compared to the reference broth dilution method for 97% (32/33) of the isolates. For other fluoroquinolones, using Streptococcus pneumoniae breakpoints, 94% (124/132) of MIC results by E-test showed either complete agreement or minor error compared to the reference broth dilution method. Fluoroquinolones show variable in vitro activity against clinical isolates of Nocardia spp., and MICs determined by the E-test show reasonable agreement with those determined by the reference broth dilution method.

A randomized prospective comparison of antibiotic tissue levels in the corpora cavernosa of patients undergoing penile prosthesis implantation using gentamicin plus cefazolin versus an oral fluoroquinolone for prophylaxis.

PURPOSE: We performed a prospective randomized trial comparing the efficacy, safety and cost of parenteral antibiotics and oral fluoroquinolones for prophylaxis in penile prosthesis surgery. MATERIALS AND METHODS: We prospectively randomized 20 consecutive patients undergoing penile prosthesis surgery to receive ofloxacin orally or gentamicin and cefazolin parenterally followed by cephradine orally. Intraoperatively corpora cavernosa tissue and simultaneous peripheral serum samples were evaluated for antibiotic levels. Median followup was 16 months (range 8 to 21, mean 15.35). RESULTS: There were no implant losses or reoperations and complications were comparable in the 2 groups. The difference in mean serum-to-tissue ratios of ofloxacin versus the combination of cefazolin and gentamicin was statistically significant (p < 0.03). The minimum inhibitory concentrations of ofloxacin met or exceeded those of the 2 most common offending organisms, Staphylococcus epidermidis and Escherichia coli, in 80% of patients, which was comparable to the results of the parenteral regimen. Cost savings of the medications alone were more than $250,000 in the ofloxacin group. By eliminating a hospital stay of the 25,000 cases of penile prosthesis placement in the United States yearly a total cost savings of more than $36 million would be realized. CONCLUSIONS: When oral ofloxacin is given for prophylaxis in penile implant surgery, the procedure may be performed on an outpatient basis and health care dollars are saved.

Inhibition of acetylating activity in an enzymatic assay for aminoglycoside antibiotics.

The radioenzymatic technique using aminoglycoside-6'-acetyltransferase is suitable for determining serum concentrations of aminoglycoside antibiotics that have a 6'-amino group. Standard curves constructed for each drug in normal human serum are generally satisfactory, but we encountered a pool of human serum (designated IN pool) that inhibited the acetylating activity of the assay. Standard curves for amikacin, kanamycin, gentamicin, and tobramycin in the acetylating assay were all abnormal with standards prepared in the IN pool. Acetylating activity was also inhibited with amikacin standards prepared in a filtrate of this serum pool. Heat inactivation (56 degrees C for 30 min) of the IN pool did not eliminate the problem. When the IN pool was diluted 1:10 in normal human serum, the standard curve obtained with amikacin was comparable to the curve with standards prepared in normal human serum. With amikacin standards prepared in a 1:2 dilution of the IN pool in normal human serum, an intermediate level of acetylating activity was observed. When this IN pool was used for the preparation of gentamicin and amikacin standards in a bioassay with Klebsiella pneumoniae ATCC 27799 as the test strain, valid standard curves and concentrations were obtained. Furthermore, no differences in the biological activity of amikacin were observed with Pseudomonas aeruginosa or Bacillus subtilis as the test strain. Excellent agreement between the microbial assay and the enzymatic assay was obtained with serum specimens tested for gentamicin (r = 0.89), tobramycin (r = 0.96), and amikacin (r = 0.96). The results obtained with the IN pool illustrate the need for regular use of check samples of known performance, independent from the standards, when determining antibiotic levels in serum.

Helicobacter pylori--in vitro susceptibility to garlic (Allium sativum) extract.

Gastric cancer is the major cancer in the developing world and one of the top two worldwide. Helicobacter pylori is a bacterium implicated in the etiology of stomach cancer. The incidence of stomach cancer is lower in individuals and populations with high Allium vegetable intakes. Allium vegetables, particularly garlic, have antibiotic activity. Standard antibiotic regimens against H. pylori are frequently ineffective in high-risk populations. As part of our study of the role of Allium vegetable intake on cancer prevention, we wished to investigate its antimicrobial activity against H. pylori. An aqueous extract of garlic cloves was standardized for its thiosulfinate concentration and tested for its antimicrobial activity on H. pylori grown on chocolate agar plates. Minimum inhibitory concentration was 40 micrograms thiosulfinate per milliliter. Staphylococcus aureus tested under the same conditions was not susceptible to garlic extract up to the maximum thiosulfinate concentration tested (160 micrograms/ml). To our knowledge, this is the first report of H. pylori's susceptibility to garlic extract of known thiosulfinate concentration. It is plausible that the sensitivity of H. pylori to garlic extract at such low concentration may be related to the reported lower risk of stomach cancer in those with a high Allium vegetable intake. Furthermore, it may identify a strategy for a low-cost intervention, with few side effects, in populations at high risk for stomach cancer, particularly where antibiotic resistance and the risk of reinfection are high.

Detection of immunoglobulin G (IgG) and IgM antibodies to Toxoplasma gondii: evaluation of four commercial immunoassay systems.

A comparative evaluation of the following commercial immunoassays for the determination of antibodies to Toxoplasma gondii was performed: Behring Diagnostics OPUS Toxo G and Toxo M, Abbott Diagnostics IMX Toxo-IgG 2.0 and Toxo-IgM, Sanofi Diagnostics Pasteur Platelia Toxo IgG and Toxo IgM, and bioMérieux Vitek VIDAS Toxo IgG and IgM. Of 676 specimens that were tested for Toxoplasma-specific immunoglobulin G (IgG) antibodies, 26% were reactive by all methods while 8% displayed some discrepancy. Of 718 specimens that were tested for Toxoplasma-specific IgM antibodies, 3% were reactive by all methods while 10% displayed some discrepancy. Analysis of discrepant specimens revealed performance shortcomings with all IgM-specific assays. The impact of such shortcomings is magnified in a population with a low prevalence of toxoplasmosis.

Application of 16S rRNA gene sequencing to identify Bordetella hinzii as the causative agent of fatal septicemia.

We report on the first case of fatal septicemia caused by Bordetella hinzii. The causative organism exhibited a biochemical profile identical to that of Bordetella avium with three commercial identification systems (API 20E, API 20 NE, and Vitek GNI+ card). However, its cellular fatty acid profile was not typical for either B. avium or previously reported strains of B. hinzii. Presumptive identification of the patient's isolate was accomplished by traditional biochemical testing, and definitive identification was achieved by 16S rRNA gene sequence analysis. Phenotypic features useful in distinguishing B. hinzii from B. avium were production of alkali from malonate and resistance to several antimicrobial agents.