Effect of Moxifloxacin on Bacterial Pathogenicity Factors in Comparison with Amoxicillin, Clarithromycin and Ceftriaxone

Zinc Blockade of SOS Response Inhibits Horizontal Transfer of Antibiotic Resistance Genes in Enteric Bacteria

The SOS response is a conserved response to DNA damage that is found in Gram-negative and Gram-positive bacteria. When DNA damage is sustained and severe, activation of error-prone DNA polymerases can induce a higher mutation rate than is normally observed, which is called the SOS mutator phenotype or hypermutation. We previously showed that zinc blocked the hypermutation response induced by quinolone antibiotics and mitomycin C in Escherichia coli and Klebsiella pneumoniae. In this study, we demonstrate that zinc blocks the SOS-induced development of chloramphenicol resistance in Enterobacter cloacae. Zinc also blocked the transfer of an extended spectrum beta-lactamase (ESBL) gene from Enterobacter to a susceptible E. coli strain. A zinc ionophore, zinc pyrithione, was ~100-fold more potent than zinc salts in inhibition of ciprofloxacin-induced hypermutation in E. cloacae. Other divalent metals, such as iron and manganese, failed to inhibit these responses. Electrophoretic mobility shift assays (EMSAs) revealed that zinc, but not iron or manganese, blocked the ability of the E. coli RecA protein to bind to single-stranded DNA, an important early step in the recognition of DNA damage in enteric bacteria. This suggests a mechanism for zinc's inhibitory effects on bacterial SOS responses, including hypermutation.

Is Kiva implant advantageous to balloon kyphoplasty in treating osteolytic metastasis to the spine? Comparison of 2 percutaneous minimal invasive spine techniques: a prospective randomized controlled short-term study

STUDY DESIGN

Prospective, parallel-group, controlled, comparative randomized study.

OBJECTIVE

To compare cement leakage rate and efficacy for vertebral body restoration of balloon kyphoplasty (BK) versus Kiva novel implant with polymethylmethacrylate (PMMA) for treating osteolytic vertebral body metastasis.

SUMMARY OF BACKGROUND DATA

Minimally invasively vertebral augmentation techniques with PMMA are mostly performed for treating osteoporotic compression fractures. The Kiva implant with PMMA offers better vertebral body restoration and less PMMA leakage than BK in osteoporotic fractures. No previous study compared leakage rate and efficacy for vertebral body restoration in traditional BK and Kiva with PMMA in osteolytic vertebral body metastases.

METHODS

This study examined 23 patients (71 ± 13 yr) with 41 osteolytic vertebral bodies, who received Kiva with low viscosity PMMA and 24 patients (70 ± 11 yr) with 43 vertebral body osteolyses, who were reinforced with BK and high viscosity PMMA. All osteolyses were graded as Tomita 1 to 3. Anterior vertebral body height ratio (AVBHr), posterior vertebral body height ratio (PVBHr), and middle vertebral body height ratio (MVBHr), Gardner kyphotic deformity, PMMA leakage and were measured and compared between the groups. Visual analogue scale and Oswestry Disability Index were used for functional outcome evaluation.

RESULTS

No patient survived after 3 months. Asymptomatic PMMA leakage occurred in 4 (9.3%) vertebrae in the BK group solely (2 to the spinal canal, in Tomita grade 3 osteolysis) Anterior, posterior and middle vertebral body height ratio, Gardner angle improved insignificantly in both groups. Visual anlogue scale and Oswestry Disability Index improved postoperatively similarly in both groups (P < 0.001).

CONCLUSION

BK and Kiva provided equally significant spinal pain relief in patients with cancer with osteolytic metastasis. The absence of cement leakage in the Kiva group and absence of neurological complication in the BK group leakages reflects the safety of both augmentation techniques even in significant osteolysis. The lack of cement leakage in the Kiva cases, although low viscosity PMMA was used, increases this implant safety in augmenting severely destructed thoracolumbar vertebrae and sacrum from osteolytic metastasis.

LEVEL OF EVIDENCE

1.

Metastatic disease in the thoracic and lumbar spine: evaluation and management

Spinal metastases are found in most patients who die of cancer. The number of patients with symptomatic spinal metastases likely will increase as therapy for the primary disease improves and as cardiovascular mortality decreases. Understanding the epidemiology of metastatic spine disease and its presentation is essential to developing a diagnostic strategy. Treatment may involve chemotherapy, corticosteroids, radiotherapy, surgery, and/or percutaneous procedures (eg, vertebroplasty, kyphoplasty). A rational treatment plan can help improve quality of life, preserve neurologic function, and prolong survival.

Influence of subinhibitory concentrations of amikacin and ciprofloxacin on morphology and adherence ability of uropathogenic strains

The influence of subinhibitory concentrations (1/2, 1/4, 1/8, 1/16 and 1/32 MIC) of amikacin and ciprofloxacin on the morphology and adherence of uropathogenic strains was studied. Intensity of morphological changes was proportional to the concentrations of these antibiotics. Morphological changes were the most prominent after bacterial exposure to sub-MICs of ciprofloxacin. These concentrations, especially 1/2 MIC of ciprofloxacin, induced the formation of filaments of E. coli, K. pneumoniae, K. oxytoca, E. cloacae and A. calcoaceticus biotype anitratus. No morphological changes were observed in P. aeruginosa, S. epidermidis and S. aureus cells after exposure to subinhibitory concentrations of both antibiotics. Sub-MICs of amikacin affected the changes in cell shape only slightly. The exposure of bacterial strains to 1/2 MIC of ciprofloxacin induced increased vacuolation of the cells. We observed shrinkage of the protoplasm and the pleated cell walls in comparison with control cells. The greatest loss of adherence ability occurred at 1/2 MIC of ciprofloxacin after a 1-d incubation.

Proteomic analysis using an unfinished bacterial genome: the effects of subminimum inhibitory concentrations of antibiotics on Mannheimia haemolytica virulence factor expression

Here we identify, using nonelectrophoretic proteomics, effects of subminimum inhibitory concentrations (subMIC) of two antibiotic preparations, chlortetracycline (CTC), and chlortetracycline-sulfamethazine (CTC + SMZ), on protein expression in the bovine respiratory pathogen Mannheimia haemolytica. The M. haemolytica genome is currently in draft form, and annotation is incomplete. Relying on the principle of gene sequence conservation across species, we used annotated genomes from closely related species to identify, confirm, and functionally annotate 495 M. haemolytica proteins. To conduct quantitative comparative proteomics, we developed a protein quantitation method based on the cross correlation function of the SEQUEST algorithm. When M. haemolytica was cultivated in the presence of 1/4 MIC of CTC and CTC + SMZ, expression of proteins involved in energy production, nucleotide metabolism, translation, and the bacterial stress response (chaperones) were affected. The most notable subMIC effect was a significant decrease in the expression of leukotoxin A, which is an important M. haemolytica virulence factor. Reduction in leukotoxin expression could be one of the molecular mechanisms responsible for the efficacy of these antibiotics against bovine respiratory disease.