Clinical efficiency and safety of Hsp90 inhibitor Novobiocin in avian tibial dyschondroplasia.

Tibial dyschondroplasia (TD) is a bone defect of broilers and other poultry birds that disturbs growth plate and it causes lameness. Previously we evaluated differential expression of multiple genes involved in growth plate angiogenesis and reported the safety and efficacious of medicinal plant root extracted for controlling TD. In this study, clinical and protective effect of an antibiotic Novobiocin (Hsp90 inhibitor) and expression of Hsp90 and proteoglycan aggrecan was examined. The chicks were divided into three groups; Control, thiram-induced TD, and Novobiocin injected TD. After the induction of TD, the Novobiocin was administered through intraperitoneal route to TD-affected birds until the end of the experiment. The expressions and localization of Hsp90 were evaluated by qRT-PCR, immunohistochemistry (IHC) and western blot, respectively. Morphological, histological examinations, and serum biomarker levels were evaluated to assess specificity and protective effects of Novobiocin. The results showed that TD causing retarded growth, enlarged growth plate, distended chondrocytes, irregular columns of cells, decreased antioxidant capacity, reduced protein levels of proteoglycan aggrecan, and upregulated in Hsp90 expression (p < 0.05) in dyschondroplastic birds as compared with control. Novobiocin treatment restored growth plate morphology, reducing width, stimulated chondrocyte differentiation, sprouting blood vessels, corrected oxidative imbalance, decreased Hsp90 expressions and increased aggrecan level. Novobiocin treatment controlled lameness and improved growth in broiler chicken induced by thiram. In conclusion, the accumulation of the cartilage and up-regulated Hsp90 are associated with TD pathogenesis and irregular chondrocyte morphology in TD is along with reduced aggrecan levels in the growth plate. Our results indicate that Novobiocin treatment has potential to reduce TD by controlling the expression of Hsp90 in addition to improve growth and hepatic toxicity in broiler chicken.

Heat shock protein 70 is necessary to improve mitochondrial bioenergetics and reverse diabetic sensory neuropathy following KU-32 therapy.

Impaired neuronal mitochondrial bioenergetics contributes to the pathophysiologic progression of diabetic peripheral neuropathy (DPN) and may be a focal point for disease management. We have demonstrated that modulating heat shock protein (Hsp) 90 and Hsp70 with the small-molecule drug KU-32 ameliorates psychosensory, electrophysiologic, morphologic, and bioenergetic deficits of DPN in animal models of type 1 diabetes. The current study used mouse models of type 1 and type 2 diabetes to determine the relationship of changes in sensory neuron mitochondrial bioenergetics to the onset of and recovery from DPN. The onset of DPN showed a tight temporal correlation with a decrease in mitochondrial bioenergetics in a genetic model of type 2 diabetes. In contrast, sensory hypoalgesia developed 10 weeks before the occurrence of significant declines in sensory neuron mitochondrial bioenergetics in the type 1 model. KU-32 therapy improved mitochondrial bioenergetics in both the type 1 and type 2 models, and this tightly correlated with a decrease in DPN. Mechanistically, improved mitochondrial function following KU-32 therapy required Hsp70, since the drug was ineffective in diabetic Hsp70 knockout mice. Our data indicate that changes in mitochondrial bioenergetics may rapidly contribute to nerve dysfunction in type 2 diabetes, but not type 1 diabetes, and that modulating Hsp70 offers an effective approach toward correcting sensory neuron bioenergetic deficits and DPN in both type 1 and type 2 diabetes.

Thai ethnomedicinal plants as resistant modifying agents for combating Acinetobacter baumannii infections.

BACKGROUND: Acinetobacter baumannii is well-recognized as an important nosocomial pathogen, however, due to their intrinsic resistance to several antibiotics, treatment options are limited. Synergistic effects between antibiotics and medicinal plants, particularly their active components, have intensively been studied as alternative approaches. METHODS: Fifty-one ethanol extracts obtained from 44 different selected medicinal plant species were tested for resistance modifying agents (RMAs) of novobiocin against A. baumannii using growth inhibition assay. RESULTS: At 250 µg/ml, Holarrhena antidysenterica, Punica granatum, Quisqualis indica, Terminalia bellirica, Terminalia chebula, and Terminalia sp. that possessed low intrinsic antibacterial activity significantly enhanced the activity of novobiocin at 1 µg/ml (1/8xminimum inhibitory concentration) against this pathogen. Holarrhena antidysenterica at 7.8 µg/ml demonstrated remarkable resistant modifying ability against A. baumannii in combination with novobiocin. The phytochemical study revealed that constituents of this medicinal plant contain alkaloids, condensed tannins, and triterpenoids. CONCLUSION: The use of Holarrhena antidysenterica in combination with novobiocin provides an effective alternative treatment for multidrug resistant A. baumannii infections.

Comparative efficacy of novobiocin and amoxicillin in experimental sepsis caused by beta-lactam-susceptible and highly resistant pneumococci.

Therapeutic alternatives are needed against infections caused by highly multidrug-resistant Streptococcus pneumoniae. Novobiocin, an old antibiotic, was tested in vitro and in a murine sepsis model against one amoxicillin-susceptible and three amoxicillin-resistant strains [minimum inhibitory concentrations (MICs) 8-64 mg/L]. Novobiocin MICs for all strains were 0.25-0.5 mg/L. In sepsis, novobiocin and amoxicillin were evaluated at 25, 50, 100 and 200 mg/kg given at 1, 5, 24 and 48 h post bacterial challenge. The most effective regimens in animals infected with the amoxicillin-susceptible strain were 200 mg/kg novobiocin and 25 mg/kg amoxicillin, achieving 100% survival and undetectable organisms in the peritoneum. Among mice infected with amoxicillin-resistant S. pneumoniae, 200 mg/kg novobiocin gave the highest protection (90-100% survivors), followed by 200mg/kg amoxicillin (60-100%), 100 mg/kg novobiocin (50-87.5%) and 50 mg/kg amoxicillin (14.3-25%). The killing effect of antibiotics in the peritoneum (mean Deltalog(10) colony-forming units/mL between treated and control mice) was as follows: 200 mg/kg novobiocin (-6.6)>200 mg/kg amoxicillin (-5.6)>100 mg/kg novobiocin (-3.7) > 50 mg/kg amoxicillin (-0.7). Total plasma and ultrafiltrate pharmacokinetics of novobiocin (200 mg/kg, single dose) in non-infected mice showed, respectively, half-lives of 151 min and 215 min, area under the concentration-time curves (AUCs) of 945.0 mgh/L and 136.6 mgh/L and maximal concentrations of 147 mg/L and 18 mg/L. Novobiocin may be a promising agent for therapy of highly beta-lactam-resistant pneumococcal infections.

Comparison of success of antibiotic therapy during lactation and results of antimicrobial susceptibility tests for bovine mastitis.

Antimicrobial susceptibility testing was conducted on a variety of mastitis pathogens. The infected quarters were subsequently treated during lactation with a commercially available product containing penicillin and novobiocin that was designed for lactating cows. Cows were treated as per the recommendations of the product manufacturer, and cures were determined by the absence of bacteria in both sets of duplicate quarter milk samples that were collected at 28 d posttreatment. Comparisons were made between the susceptibility of the bacteria and the therapeutic success or failure. All isolates tested were considered to be susceptible to the penicillin and novobiocin combination. Bacteriologic cure rates for newly acquired Staphylococcus aureus intramammary infection (IMI) (< 2 wk in duration) at 28 d posttreatment were 70%. Cure rates for chronic Staph. aureus IMI (> 4 wk duration) were much lower (35%), reaffirming previous reports of the intractable nature of chronic Staph. aureus IMI. Cure rates for subclinical IMI caused by other organisms were 90% for Streptococcus agalactiae, 91% for Streptococcus uberis, 90% for Streptococcus dysgalactiae, 77% for other Streptococcus spp., and 71% for Staphylococcus spp. other than Staph. aureus. In vitro testing was considered to be a predictor of therapy outcome for IMI caused by Staphylococcus spp., newly acquired Staph. aureus, Strep. uberis, Strep. dysgalactiae, and Strep. agalactiae, but was not considered to be a useful predictor of efficacy for chronic IMI caused by Staph. aureus.

Treatment of experimental endocarditis due to multidrug resistant Enterococcus faecium with ciprofloxacin and novobiocin.

The effectiveness of ciprofloxacin and/or novobiocin therapy was assessed for experimental endocarditis caused by three strains of Enterococcus faecium resistant to ampicillin, vancomycin, and aminoglycosides. Rabbits with endocarditis caused by two of the strains had a significant decrease in bacterial counts in vegetations when treated with both antibiotics. Further studies using combination therapy with ciprofloxacin plus novobiocin for multidrug resistant strains of E. faecium are warranted.

Antimicrobial susceptibility of Staphylococcus hyicus isolated from exudative epidermitis in pigs.

Exudative epidermitis or greasy pig syndrome is caused by the coagulase-variable staphylococcal species Staphylococcus hyicus. Treatment of this disease is problematic because of the limited number of antimicrobial agents available for this purpose. Thirteen antimicrobial agents were evaluated for their activities against 100 S. hyicus strains isolated from pigs with exudative epidermitis. Novobiocin was the most active compound tested, with an MIC for 90% of the strains tested (MIC90) of < or = 0.06 microgram/ml. Enrofloxacin, ampicillin, and ceftiofur were the next most active compounds, with MIC90s of 0.25, 0.5, and 1.0 microgram/ml, respectively. However, 41.4% of the 99 strains tested were positive for beta-lactamase production. The MIC90s of erythromycin, tetracycline, and streptomycin were > 32.0 micrograms/ml. Initial testing with sulfadiazine-trimethoprim yielded an MIC90 of > 64.0 micrograms/ml, but subsequent testing with thymidine phosphorylase-supplemented medium yielded an MIC90 of 0.06 microgram/ml. Both lincomycin and spectinomycin were relatively inactive against the S. hyicus strains tested, with MIC90s of > 64.0 and > 128.0 micrograms/ml, respectively. However, the combination of the two compounds at ratios of 1:2 (lincomycin to spectinomycin) and 1:8 were more active, with MIC90s of 16.0 and 4.0 micrograms/ml, respectively. These results indicate that novobiocin and sulfadiazine-trimethoprim were the most active compounds tested against the S. hyicus strains isolated from pigs with exudative epidermitis. Furthermore, the combination of lincomycin and spectinomycin was more active than the individual compounds against the strains tested.

Efficacy of short courses of oral novobiocin-rifampin in eradicating carrier state of methicillin-resistant Staphylococcus aureus and in vitro killing studies of clinical isolates.

Methicillin-resistant Staphylococcus aureus (MRSA) is an important nosocomial infection problem. Colonization appears to be more common than invasive disease is. Eradication of colonization or the carrier state could limit the spread of MRSA, thus reducing the potential for mortality and morbidity in other patients. The detection of patients with MRSA infection in a rehabilitation ward led to a study of the combination of novobiocin-rifampin in vivo and in vitro. We found that 300 mg of rifampin plus 500 mg of novobiocin orally twice daily for 5 days, in 18 courses of treatment given to 12 patients, resulted in the clearing of MRSA in 79% of the evaluable courses and 81% of the evaluable sites. A second course cleared MRSA from one of the patients with a treatment failure. Side effects were not noted. All 18 pretherapy isolates were susceptible to either drug in vitro, but 1 of 2 posttherapy isolates was rifampin resistant. Timed-kill studies demonstrated that the rate of killing was the same with either drug alone or both drugs together. Pretherapy isolates from treatment successes or failure were killed at the same rate by the drug combination. However, with the rifampin-resistant isolate killing ceased after 48 h. Results of this study suggest that previously untreated patients are likely to have isolates that are susceptible to the combination of drugs and that the combination is commonly effective in eradicating MRSA carriage. Since the regimen is orally administered, and thus convenient, in conjunction with other measures it has the promise of reducing the spread of MRSA in hospitals.

Should novobiocin be clinically re-evaluated?

The current novobiocin spectrum of antimicrobial activity was evaluated by testing 585 staphylococci (393 oxacillin-resistant) and 779 other bacterial strains. Novobiocin inhibited 98.5% of all staphylococcal isolates (MIC 90, 0.25 micrograms/ml) and a significant number of other Gram-positive species at less than or equal to 1 microgram/ml. Pathogenic Neisseria, Haemophilus influenzae, and Branhamella catarrhalis were also very susceptible to novobiocin, e.g., MIC 100, less than or equal to 1 microgram/ml. These results indicate that novobiocin may have a role in contemporary chemotherapy of oxacillin-resistant staphylococcal and other infections.

Efficacy of lincosaminide antibiotics in the treatment of experimental staphylococcal mastitis in lactating mice.

Staphylococcus aureus is a frequent cause of bovine mastitis worldwide. A model that may predict the efficacy of antimicrobial agents in the treatment of bovine mastitis induced by Staph. aureus was developed in lactating mice. Infection was established by the inoculation of lactating CF1 mice with Staph. aureus into the mammary gland via the teat duct. At the dose of bacteria used, 85-90% of the inoculated, untreated animals developed a nonlethal, acute mastitis within 48 h. Antibiotic treatment was administered subcutaneously or by the intramammary route. Lincosaminide antibiotics including lincomycin, clindamycin, and pirlimycin were evaluated in this system. Other compounds which have been used in therapy of bovine mastitis including novobiocin, penicillin G, ampicillin, cloxacillin and rifamycin-SV were used as reference antibiotics. Pirlimycin was the most effective of the antibiotics tested in this standardized system. Depending upon the route of administration, this novel lincosaminide was 15 to 95-fold more effective than clindamycin, three- to six-fold better than lincomycin, two- to ten-fold more effective than novobiocin, 13- to 17-times more effective than cloxacillin and 8- to 22-times better than rifamycin-SV on a weight-dose comparison. Penicillin G and ampicillin were the least effective drugs tested against mastitis induced by the beta-lactamase producing strain of Staph. aureus used in these assays. Pharmacokinetic experiments suggested that the greater effectiveness of pirlimycin compared to clindamycin and lincomycin was due to increased affinity for and prolonged retention in the mammary gland.

Pseudomonas cepacia: the sensitivity of nosocomial strains to new antibiotics.

Pseudomonas cepacia, considered a phytopathogenic organism for many years, has been shown recently to be widely distributed geographically. The hospital environment has become an important source of this organism but the resistance of Ps. cepacia to most antibiotics has made the treatment of infections a problem. One hundred per cent of the strains tested have proved to be sensitive to the sulphonamides and to novobiocin, 93.0% to the combination of trimethoprim and sulfamethoxazole (co-trimoxazole); 85.2% to minocycline; 77.8% to chloramphenicol and dibekacin and 44.4% to nalidixic acid. One hundred per cent of the strains exhibit resistance to ampicillin, cephalothin, cefamandole, cefoxitin, colistin, cefuroxime, tetracycline and cefazolin; 88.9% to amikacin, tobramycin and sisomycin; 85.2% to carbenicillin. The new beta-lactams, apalcillin, ceftazidime, N-formimidoyl-thienamycin, piperacillin, cefotaxime and azlocillin proved to be the most potent of the molecules tested, inhibiting 90% of the strains, at concentrations of 4, 8, 8, 8, 32 and 16 mg/l and 100% of the strains at 8, 16, 16, 32, 32 and 64 mg/l, respectively. In contrast to the usual sensitivity patterns of Pseudomonas spp, Ps. cepacia has been shown to be resistant to colistin, cefsulodin and the aminoglycosides. However, unlike Ps. aeruginosa, Ps. cepacia has been shown, by the dilution method, to be sensitive to co-trimoxazole, 92.3% of the strains being inhibited by 16 mg/l.

Pseudomembranous colitis associated with antibiotic therapy - an emerging entity.

Two cases of pseudomembranous colitis are presented. The first patient had been treated with novobiocin-tetracycline and penicillin, and two weeks later developed severe fulminating diarrhea with ascites and bilateral pleural effusions which did not respond to intravenous ACTH. Subsequently she underwent subtotal colectomy and made a rapid and complete recovery. The second patient developed severe diarrhea two weeks after a 10-day course of clindamycin. She was treated with intravenous ACTH, oral Lactobacillus and a fecal enema and made a complete recovery.These cases reconfirm the importance of antibiotics as etiologic agents in this disease. They also stress the classic sigmoidoscopic and histologic findings that should facilitate prompt and rapid diagnosis.