In vitro and in vivo antitumoral activity of a ternary copper (II) complex.

Recently, a high number of copper derivatives has been evaluated as DNA-targeting metallodrugs, due to the lower toxicity and its potential to cleave DNA. Several strategies have been testing to develop metal compounds effective against tumour cells. In this work, the ternary copper (doxycycline)-(1,10-phenanthroline) complex [Cu(dox)(phen)]2+ was especially designed as an antitumoral drug, previously showing high cytotoxicity and DNA cleavage activity. We aimed to further investigate the in vitro cytotoxic activity in both tumoral and non-tumoral cells, in vitro genotoxic potential, and in vivo antitumor activity using BALB/C mouse injected with sarcoma S180 and Ehrlich cell lines. Our results indicated that this compound exhibits a moderate genotoxic potential, with selective growth inhibition of tumor cells, especially the murine melanoma B16F10. Its main mechanism of action seems to be through ROS generation. We have further shown a significant reduction of the implanted tumor size in the animal model, suggesting that this compound has great antitumoral potential against many tumor types. [Cu(dox)(phen)]2+ is selectively cytotoxic for melanoma B16F10 and showed high chemotherapeutic potential in vivo against implanted sarcoma S180 and Ehrlich ascites tumours.

Synthesis and Characterization of Photoactivatable Doxycycline Analogues Bearing Two-Photon-Sensitive Photoremovable Groups Suitable for Light-Induced Gene Expression.

We report the synthesis and photolytic properties of caged 9-aminodoxycycline derivatives modified with 2-{4'-bis-[2-(2methoxyethoxy)ethyl]-4-nitrobiphenyl-3-yl}prop-1-oxy (EANBP) and PEG7-ylated (7-diethylamino-2-oxo-2H-chromen-4-yl)methyl (PEG7-DEACM) groups. 9-Aminodoxycycline is a tetracycline analogue capable of activating transcription through the inducible TetOn transgene expression system and can be regioselectively coupled to two-photon-sensitive photo-removable protecting groups by carbamoylation. The EANBP-based caged 9-aminodoxycycline showed complex photochemical reactions but did release 10 % of 9-aminodoxycycline. However, 9-(PEG7-DEACMamino)doxycycline exhibited excellent photolysis efficiency at 405 nm with quantitative release of 9-aminodoxycycline and a 0.21 uncaging quantum yield. Thanks to the good two-photon sensitivity of the DEACM chromophore, 9-aminodoxycycline release by two-photon photolysis is possible, with calculated action cross-sections of up to 4.0 GM at 740 nm. Therefore, 9-(PEG7-DEACMamino)doxycycline represents a very attractive tool for the development of a light-induced gene expression method in living cells.

Synthesis and antibacterial activity of doxycycline neoglycosides.

A set of 37 doxycycline neoglycosides were prepared, mediated via a C-9 alkoxyamino-glycyl-based spacer reminiscent of that of tigecycline. Subsequent in vitro antibacterial assays against representative drug-resistant Gram negative and Gram positive strains revealed a sugar-dependent activity profile and one doxycycline neoglycoside, the 2'-amino-α-D-glucoside conjugate, to rival that of the parent pharmacophore. In contrast, the representative tetracycline-susceptible strain E. coli 25922 was found to be relatively responsive to a range of doxycycline neoglycosides. This study also extends the use of aminosugars in the context of neoglycosylation via a simple two-step strategy anticipated to be broadly applicable for neoglycorandomization.

Doxycycline-dependent photoactivated gene expression in eukaryotic systems.

High spatial and temporal resolution of conditional gene expression is typically difficult to achieve in whole tissues or organisms. We synthesized two reversibly inhibited, photoactivatable ('caged') doxycycline derivatives with different membrane permeabilities for precise spatial and temporal light-controlled activation of transgenes based on the 'Tet-on' system. After incubation with caged doxycycline or caged cyanodoxycycline, we induced gene expression by local irradiation with UV light or by two-photon uncaging in diverse biological systems, including mouse organotypic brain cultures, developing mouse embryos and Xenopus laevis tadpoles. The amount of UV light needed for induction was harmless as we detected no signs of toxicity. This method allows high-resolution conditional transgene expression at different spatial scales, ranging from single cells to entire complex organisms.

Genotoxic and cytotoxic effects of doxycycline in cultured human peripheral blood lymphocytes.

Doxycycline (DOX) is a broad-spectrum tetracycline antibiotic used in the treatment of many infections. In this study, the genotoxic and cytotoxic effects of DOX in cultured human peripheral blood lymphocytes were investigated by measuring chromosome aberrations (CAs), cytokinesis-block micronucleus (CBMN) assay, mitotic index (MI), and nuclear division index (NDI). Cultures were treated with DOX at three concentrations (2, 4, and 6 µg/mL) for 48 hours. Mitomycin C (MMC) was used as a positive control. All the tested concentrations of DOX for MI and the higher concentrations (4 and 6 µg/mL) for NDI significantly decreased mitotic activity. However, there are no significant differences between negative control and all the tested concentrations of DOX for CA and MN frequencies. In conclusion, our results indicate that DOX has a cytotoxic effect, but not a genotoxic effect, on human peripheral blood lymphocyte cultures. Further detailed studies, especially about the cell-cycle kinetics of DOX, are required to elucidate the decreases in dividing cells and make a possible risk assessment on cells of patients receiving therapy with this drug. Further, if the specific cytostatic and cytotoxic potential of DOX to different types of cancer cells is investigated in detail, it may also have been used as an antitumoral drug.

Downregulation of TFPI in breast cancer cells induces tyrosine phosphorylation signaling and increases metastatic growth by stimulating cell motility.

BACKGROUND: Increased hemostatic activity is common in many cancer types and often causes additional complications and even death. Circumstantial evidence suggests that tissue factor pathway inhibitor-1 (TFPI) plays a role in cancer development. We recently reported that downregulation of TFPI inhibited apoptosis in a breast cancer cell line. In this study, we investigated the effects of TFPI on self-sustained growth and motility of these cells, and of another invasive breast cancer cell type (MDA-MB-231). METHODS: Stable cell lines with TFPI (both α and ß) and only TFPIß downregulated were created using RNA interference technology. We investigated the ability of the transduced cells to grow, when seeded at low densities, and to form colonies, along with metastatic characteristics such as adhesion, migration and invasion. RESULTS: Downregulation of TFPI was associated with increased self-sustained cell growth. An increase in cell attachment and spreading was observed to collagen type I, together with elevated levels of integrin α2. Downregulation of TFPI also stimulated migration and invasion of cells, and elevated MMP activity was involved in the increased invasion observed. Surprisingly, equivalent results were observed when TFPIß was downregulated, revealing a novel function of this isoform in cancer metastasis. CONCLUSIONS: Our results suggest an anti-metastatic effect of TFPI and may provide a novel therapeutic approach in cancer.

Comparative evaluation of the efficacy of 10% doxycycline hyclate in the periodontal treatment of smokers - a clinical and microbiological study.

PURPOSE: The aim of this present clinical and microbiological study was to evaluate the efficacy of the association of locally delivered 10% doxycycline hyclate (Atridox®) with scaling and root planing in the periodontal treatment of smokers. MATERIALS AND METHODS: Forty-five patients with chronic periodontitis having a minimum of two periodontal pockets (>5 mm) and satisfying the inclusion and exclusion criteria were selected. Sites were randomly assigned to scaling and root planing (SRP) or scaling and root planing followed by local application of 10% doxycycline hyclate (SRP-D). Plaque index (PI), gingival index (GI), periodontal pocket depth (PD), clinical attachment level (CAL) and total anaerobic colony count (TACC) were recorded at baseline, one month and three months respectively. Differences between baseline and each period were considered for analysis. RESULTS: There was a significant reduction in plaque score, gingival score, periodontal pocket depth and total anaerobic colony count from baseline in both groups at all time intervals. Clinical attachment level showed a significant gain in both groups. However, PD reduction (P < 0.001) and CAL gain (P < 0.001) were significant in the test group as compared to control at the end of 3 months. Reduction in total anaerobic colony count from baseline was significant (P = 0.02) in the test group compared to control at the end of 3 months. CONCLUSIONS: The use of locally delivered doxycycline may constitute an important adjunct for the treatment of chronic periodontitis in smokers.

Click-chemistry-derived tetracycline-amino acid conjugates exhibiting exceptional potency and exclusive recognition of the reverse tet repressor.

A click-chemistry-based synthesis of biologically active doxycycline-amino acid conjugates is described. Starting from 9-aminodoxycycline derivatives and complementary functionalized amino acids, ligation was accomplished by copper(I)-catalyzed azide-alkyne [3+2] cycloaddition (CuAAC). The final products were tested in a variety of TetR and revTetR systems, and the C-terminally linked phenylalanine conjugate 12 c exhibited high selectivity for revTetR over TetR. Besides the unique property of the specific effector 12 c to effectively differentiate TetR and its reverse phenotype, the test compound proved to be almost devoid of any antibacterial activity; this will be highly beneficial for future applications to control gene expression in bacterial systems.

Effective and safe combination therapy for severe acne vulgaris: a randomized, vehicle-controlled, double-blind study of adapalene 0.1%-benzoyl peroxide 2.5% fixed-dose combination gel with doxycycline hyclate 100 mg.

There is a paucity of treatment options for severe acne vulgaris aside from oral isotretinoin. This randomized, vehicle-controlled, multicenter, double-blind study evaluated the efficacy and safety of combination therapy using adapalene 0.1%-benzoyl peroxide 2.5% (A/BPO) fixed-dose combination gel with doxycycline hyclate 100 mg in the treatment of severe acne vulgaris. A total of 459 participants were randomized in a 1:1 ratio to receive oral doxycycline hyclate 100 mg once daily and either A/BPO or vehicle once daily for 12 weeks. Efficacy in the A/BPO with doxycycline group was demonstrated as early as week 2 compared with the vehicle arm for total, inflammatory, and noninflammatory lesions (all P < .005). At week 12, this combination was superior to vehicle with doxycycline in reducing total, inflammatory, and noninflammatory lesion counts (an added incremental benefit of 23%, 24%, and 21%, respectively), as well as for global success and overall participant satisfaction (all P < .001). Digital UV fluorescence photography demonstrated a rapid reduction in Propionibacterium acnes in the A/BPO with doxycycline group, particularly within the first 4 weeks. These findings provide evidence on the efficacy of combining A/BPO and the oral antibiotic doxycycline in the treatment of severe acne vulgaris.

Systemic MMP inhibition for periodontal wound repair: results of a multi-centre randomized-controlled clinical trial.

AIM: This multi-centre, prospective, controlled trial was designed to examine the biological response of the matrix metalloproteinase(MMP) inhibitor subantimicrobial dose doxycycline (SDD) combined with access flap surgery on periodontal wound repair in patients with chronic severe periodontitis. MATERIAL AND METHODS: Seventy subjects were enrolled into a 12-month, randomized, placebo-controlled, double-masked trial to evaluate disease response to 6 months therapy and "wash-out" of either placebo+surgery or SDD (20 mg b.i.d.)+surgery. Primary outcome measure included clinical attachment levels (CAL) and secondary outcomes included probing depth (PD), bleeding on probing (BOP), as well as gingival crevicular fluid bone marker assessment [collagen telopeptides (ICTP)]. These measurements were taken at baseline through 12 months post-surgery and drug administration. RESULTS: Patients treated with SDD and surgery demonstrated stronger reductions in PD in surgically-treated sites of >or=7 mm as well as gains in CAL (p<0.004). Furthermore, SDD+surgery resulted in short-term reductions in ICTP levels compared with placebo. Rebounds in ICTP levels and clinical parameters occurred when SDD was withdrawn. CONCLUSIONS: The results from this multi-centre study suggests that SDD in combination with surgery improves the short-term response of periodontal therapy by reducing PD, increasing CAL gain and inhibiting early stage bone resorption.

The effect of doxycycline hyclate, chlorhexidine gluconate, and minocycline hydrochloride on osteoblastic proliferation and differentiation in vitro.

BACKGROUND: The purpose of this study was to determine the effect of the active substance of three types of local delivery systems, doxycycline hyclate 10% (DOXY), chlorhexidine gluconate, 2.5 mg (CHX), and minocycline hydrochloride, 1 mg (MINO), on osteoblastic cell proliferation and differentiation. METHODS: There were four groups: control osteoblastic cells (OB) alone, OB + DOXY, OB + CHX, and OB + MINO. Trypan blue and MTT [3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide] assays were used to test osteoblastic cell viability. Cell differentiation was tested by measuring alkaline phosphatase levels. Osteoblast morphology was investigated by light and scanning electron microscopy. RESULTS: At a concentration of 0.5 mg/ml, the Trypan blue test showed that DOXY, MINO, and CHX had significant toxicity effects on osteoblast cells compared to the control group, with a mean cell viability of 84%, 74%, and 51%, respectively (P <0.05). The MTT test showed that the control and DOXY groups were statistically significantly different (P <0.05) compared to CHX and MINO groups. The DOXY group showed a significantly higher alkaline phosphatase activity ( approximately 56%) than the control and MINO groups, and it was nearly 178% higher than the CHX group (P <0.05). The morphology of the osteoblasts seemed to be slightly altered when they were incubated with DOXY; however, with MINO, they appeared rounded with minimal attachment. In the CHX group, the osteoblasts assumed a shape of a very thin filopodia with a volcano-like nucleus. CONCLUSIONS: At a concentration of 0.5 mg/ml, CHX and, to a lesser extent, MINO had a cytotoxic effect on osteoblast proliferation in vitro. However, DOXY seemed to enhance maturation and differentiation rather than proliferation. In addition to DOXY's beneficial effect as an adjunctive therapy to mechanical debridement in the treatment of periodontal disease, it may have an effect on periodontal regeneration.

Comparison of WHO and US FDA biowaiver dissolution test conditions using bioequivalent doxycycline hyclate drug products.

OBJECTIVES: The dissolution characteristics of immediate-release doxycycline hyclate products with certified in-vivo bioequivalence to the innovator product were tested with a view to possible application of biowaiver-based approval. METHODS: Five products were tested using US Pharmacopeia Apparatus 2: Antodox 100 mg hard gelatin capsules, Doxycyclin AL 100 T tablets, Doxycyclin-ratiopharm 100 soft gelatin capsules, Doxycyclin STADA 100 mg tablets and Doxy-Wolff 100 mg tablets. Three compendial buffers were used as dissolution media: simulated gastric fluid without pepsin, pH 1.2, acetate buffer, pH 4.5, and simulated intestinal fluid without pancreatin, pH 6.8. Results were obtained at two paddle speeds recommended for biowaiver applications: 75 rpm (World Health Organization; WHO) and 50 rpm (US Food and Drug Administration; US FDA). KEY FINDINGS: The results for the tablets and hard gelatin capsules indicate that a paddle speed of 75 rpm is more representative than 50 rpm, since 75 rpm generates dissolution profiles corresponding more closely to the in-vivo profiles than those at 50 rpm. For evaluating soft gelatin capsule formulations with lipid fill, both US FDA and WHO methods were found to be over-discriminating. CONCLUSIONS: Bioequivalence of immediate-release doxycycline hyclate tablets and hard gelatin capsules, but not soft gelatin capsules, can be evaluated in vitro using the biowaiver dissolution test conditions specified by the WHO.

A sustained-release formulation of doxycycline hyclate (Atridox) prevents simultaneous infection of Anaplasma phagocytophilum and Borrelia burgdorferi transmitted by tick bite.

Current prophylaxis for infected tick bites consists of personal protective measures directed towards ticks. This study compared the efficacy of a single oral dose of doxycycline with that of a single injection of sustained-release doxycycline in a model of Lyme borreliosis and Anaplasma phagocytophilum infection. Dosages of doxycycline were equilibrated based on previously determined peak plasma levels in mice [oral, 2.4 microg (ml plasma)(-1); sustained release, 1.9 microg (ml plasma)(-1)] determined 8 h after inoculation. In challenge experiments where five Borrelia burgdorferi-infected and five A. phagocytophilum-infected nymphs were used per mouse, only 20 and 30 % of mice were protected from B. burgdorferi and A. phagocytophilum infection, respectively, using oral doxycycline. In contrast, 100 % of mice receiving sustained-release doxycycline were protected from A. phagocytophilum infection, as indicated by real-time PCR of blood samples, quantitative PCR and culture isolation of spleen samples, and protected against B. burgdorferi infection as demonstrated by culture of ear, heart and bladder. Although 15-40 copies of A. phagocytophilum could be amplified from the spleens of mice treated with sustained-release doxycycline, no viable A. phagocytophilum from these spleens could be cultured in HL-60 cells. In contrast, 7/10 mice receiving oral doxycycline were PCR- and culture-positive for A. phagocytophilum, with copy numbers ranging from 800 to 10 000 within the spleen, as determined by quantitative PCR. Other correlates with A. phagocytophilum infection included a significant difference in spleen mass (mean of 110 mg for sustained-release treatment versus a mean of 230 mg for oral treatment) and the number of splenic lymphoid nodules (mean of 8 for sustained-release treatment versus mean of 12.5 for oral doxycycline) as determined by histopathology. These studies indicate that a single injection of a sustained-release formulation antibiotic may offer a viable prophylactic treatment option for multiple infectious agents in patients presenting with tick bites.

Regeneration of degree ii furcation defects with a 4% doxycycline hyclate bioabsorbable barrier.

BACKGROUND: Bacterial contamination of a healing regenerative site has been shown to affect the response to therapy adversely. Doxycycline possesses antibacterial properties as well as other biologic actions that may result in an increased production and maintenance of collagen and bone. The purpose of this study was to assess if the sustained release of 4% doxycycline through a bioabsorbable barrier would enhance the regenerative outcomes of healing furcation sites. METHODS: Individuals with a single degree II furcation defect in a mandibular molar participated. They were assigned randomly to one of three treatment groups: poly(DL-lactide) polylactic acid (PLA) barrier containing 4% doxycycline hyclate + demineralized freeze-dried bone allograft (DFDBA) (BG+PDox); poly(DL-lactide) PLA barrier without doxycycline + DFDBA (BG+P); or DFDBA alone (BG). Clinical parameters included vertical probing depth (VPD), vertical clinical attachment level (VCAL), gingival recession, and horizontal probing depth (HPD). Intrasurgical measurements to calculate vertical and horizontal furcation fill were obtained at the time of surgery (baseline) and during a reentry procedure 9 months later. Statistical tests were used to assess changes in the clinical and surgical parameters before and after treatment among groups and within each group. RESULTS: Mean changes at 9 months for all groups yielded VPD reductions and VCAL gains. However, no significant difference was noted for the group that was treated with 4% doxycycline barrier compared to the other two groups. Vertical bone fill was 0.89, 1.44, and 1.18 mm for the BG+PDox, BG+P, and BG groups, respectively. Furcation horizontal bone was 2.33, 2.11, and 1.18 mm for the BG+PDox, BG+P, and BG groups, respectively. CONCLUSIONS: Addition of doxycycline to the guided tissue regeneration barrier did not enhance treatment outcomes compared to the non-antibiotic-loaded barrier or bone graft alone. All treatment modalities provided similar improvement in clinical and intrasurgical parameters.

Pharmacokinetic study of an injectable long-acting parenteral formulation of doxycycline hyclate in calves.

Doxycycline hyclate (DOX-h) can be regarded as a time-dependant antibacterial. Hence, a parenteral long-acting formulation may be regarded as more pharmacologically sound. A poloxamer-based matrix was used to produce a long-acting injectable preparation (DOX-h-LA) and its serum concentrations vs. time profile investigated after its s.c. injection to calves. Serum concentrations profiles for such a prepartion were compared to the corresponding profiles obtained with an aqueous formulation of DOX-h injected either i.m. or i.v. in 10 calves in a crossover study at dose of 10mg/kg, with washout periods. DOX-h-LA showed the greatest values for bioavailability (602%); maximum serum concentration (C(max)) value was 1.99microg/mL with a time to reach C(max) (T(max)) of 25h and an elimination half-life of 40.81h. Considering minimum effective serum concentration of 0.5microg/mL a dose-interval of 80h can be achieved for DOX-h-LA, and only 9.7h and 17h after the i.v. or i.m. administration of DOX-h, respectively.

Pharmacokinetics after administration of an injectable experimental long-acting parenteral formulation of doxycycline hyclate in goats.

OBJECTIVE: To determine the pharmacokinetics after SC administration of an experimental, long-acting parenteral formulation of doxycycline hyclate in a poloxamer-based matrix and after IV and IM administration of an aqueous formulation of doxycycline hyclate in goats. ANIMALS: 30 clinically normal adult goats. PROCEDURES: Goats were allocated to 3 groups (10 goats/group). One group of goats received doxycycline hyclate (10 mg/kg) IM, a second group received the same dosage of doxycycline hyclate IV, and the third group received the long-acting parenteral formulation of doxycycline hyclate SC. Serum concentrations of doxycycline were determined before and at various intervals after administration. RESULTS: The long-acting parenteral formulation of doxycycline hyclate had the greatest bioavailability (545%); mean +/- SD maximum serum concentration was 2.4 +/- 0.95 microg/mL, peak time to maximum concentration was 19.23 +/- 2.03 hours, and elimination half-life was 40.92 +/- 4.25 hours. CONCLUSIONS AND CLINICAL RELEVANCE: Results indicated that the long-acting parenteral formulation of doxycycline hyclate distributed quickly and widely throughout the body after a single dose administered SC, and there was a prolonged half-life. Bioavailability of the longacting parenteral formulation of doxycycline hyclate after SC administration was excellent, compared with bioavailability after IV and IM administration of an aqueous formulation of doxycycline hyclate. Although no local tissue irritation and adverse effects were detected, clinical assessment of drug-residues and toxicologic evaluations are warranted before this long-acting parenteral formulation of doxycycline hyclate can be considered for use in goats with bacterial infections.

Antibacterial activity and drug release of chitosan sponge containing doxycycline hyclate.

The purpose of the present study was to develop and characterize the chitosan sponges loading with doxycycline hyclate and their antibacterial activities. The pore density of chitosan sponge prepared with freeze drying technique was increased as the higher concentrated chitosan solution was used. The sponge prepared from 10% w/w of the chitosan solution and crosslinking with glutaraldehyde solution was utilized for loading with doxycycline hyclate. The drug release and sustainable antibacterial activity of fabricated sponge were assessed using dissolution test and agar diffusion test, respectively. Drug release from non-crosslinked sponge into phosphate buffer pH7.4 was slower than that from crosslinked sponge since the former could absorb the medium and form gel to retard the initial drug diffusion. Sustainable antibacterial activity of developed sponge was evident against S. aureus and E. coli. In conclusion, the in vitro release profile and antibacterial efficiency indicated that doxycycline hyclate could be sustained using chitosan sponge.

Comparative evaluation of subgingivally delivered 10% doxycycline hyclate and xanthan-based chlorhexidine gels in the treatment of chronic periodontitis.

AIM: The aim of this study was to evaluate and compare the efficacy of subgingivally delivered 10% doxycycline hyclate and xanthan based chlorhexidine gels when used as an adjunct to scaling and root planing (SRP) in the treatment of chronic periodontitis. METHODS AND MATERIALS: A randomized, controlled, single center study was conducted involving 90 sites in 30 patients suffering from moderate to advanced chronic periodontitis. Each patient contributed three sites which were randomized to three treatment groups: SRP + insertion of doxycycline gel [SRP+DH], SRP + insertion of chlorhexidine gel [SRP+CHX]), and SRP alone [SRP]. Gingival index (GI), plaque index (PI), probing pocket depth (PPD), and clinical attachment level (CAL) were recorded at baseline, 1 month, and 3 months post therapy. RESULTS: All treatments showed significant reductions in PPD and CAL at 1 and 3 months when compared to baseline values (p<0.001). At 3 months, sites treated with SRP+DH and SRP+CHX showed an additional reduction in PPD of 0.86 +/- 1.0 mm and 0.66 +/- 1.58 mm, respectively, significantly greater than SRP alone (p<0.02). Differences in mean PPD reduction between SRP+DH and SRP+CHX were not significant (p=0.46). At 3 months, differences in relative CAL between both SRP+DH (0.80 +/- 0.92) and SRP+CHX (0.63 +/- 1.47) and SRP alone were statistically significant (p<0.02). Differences in relative CAL between SRP+DH and SRP+CHX were not significant (p=0.54). CONCLUSION: The results suggest treatment with 10% doxycycline hyclate and xanthan based chlorhexidine gels as an adjunct to SRP improves PPD and CAL patients with periodontitis compared to SRP alone. CLINICAL SIGNIFICANCE: The use of local drug therapy may refocus the need for surgical periodontal therapy toward deeper pockets.

A New Combination of a Pleuromutilin Derivative and Doxycycline for Treatment of Multidrug-Resistant Acinetobacter baumannii.

Multidrug-resistant (MDR) Acinetobacter baumannii is one of the most difficult Gram-negative bacteria to treat and eradicate. In a cell-based screening of pleuromutilin derivatives against a drug sensitive A. baumannii strain, new molecules (2-4) exhibit bacteriostatic activity with 3.13 µg/mL concentration and 1 shows bactericidal activity with an MBC of 6.25 µg/mL. The pleuromutilin derivative 1 displays strong synergistic effects with doxycycline in a wide range of concentrations. A 35/1 ratio of 1 and doxycycline (1-Dox 35/1) kills drug susceptible A. baumannii with the MBC of 2.0 µg/mL and an MDR A. baumannii with the MBC of 3.13 µg/mL. In vitro anti-Acinetobacter activity of 1-Dox 35/1 is superior to that of clinical drugs such as tobramycin, tigecycline, and colistin. The efficacy of 1-Dox 35/1 is evaluated in a mouse septicemia model; treatment of the infected C57BL/6 mice with 1-Dox 35/1 protects from lethal infection of A. baumannii with an ED50 value of <2.0 mg/kg.

Clinical relevance of different IgG and IgM serum antibody responses to Borrelia burgdorferi after antibiotic therapy for erythema migrans: long-term follow-up study of 113 patients.

OBJECTIVES: To investigate the kinetics of anti-Borrelia burgdorferi antibodies for a minimum of 1 year after antibiotic therapy in patients with erythema migrans (EM) and to correlate antibody titer kinetics with clinical variables. DESIGN: Retrospective study of serial anti-B burgdorferi antibodies in correlation to clinical variables. SETTING: University-based hospital. PATIENTS: One hundred thirteen patients with EM. INTERVENTIONS: Pretreatment and a median of 4 consecutive posttreatment serum samples from median follow-up of more than 400 days were simultaneously investigated for anti-B burgdorferi IgG and IgM antibodies. Semiquantitative titers were plotted to identify different groups of antibody kinetics. Individual patients were then stratified to those groups according to their antibody development. A statistical comparison of clinical and therapy-related characteristics among the serologic groups was performed. RESULTS: Anti-B burgdorferi IgG and IgM antibody titers developed in 3 distinct courses: persistent positivity across follow-up (IgG: 12 patients, 11%; IgM: 14, 12%), persistent negativity (IgG: 63, 56%; IgM: 47, 42%), and decrease of a positive pretreatment titer to a negative titer approximately 5 months after therapy (IgG: 34, 30%; IgM: 49, 43%). Statistics revealed significant correlations only between persistent positive IgG titers and long disease duration or large EM lesions before therapy. CONCLUSIONS: Long duration or large size of EM before therapy correlates with persistence of a positive anti- B burgdorferi IgG antibody titer after therapy. Serologic profiles do not depend on the type or duration of therapy or the clinical course thereafter. Thus, antibody testing in the follow-up of patients with EM is inappropriate for the assessment of therapeutic response.