Sunday, May 27, 2007
Zymar (Gatifloxacin 0.3%) Shows Excellent Gram-Negative Activity Against Serratia marcescens and Pseudomonas aeruginosa
Cornea. 2007 Jun
From the Charles T. Campbell Ophthalmic Microbiology Laboratory, UPMC Eye Center, Ophthalmology and Visual Sciences Research Center, Department of Ophthalmology, University of Pittsburgh School of Medicine, Pittsburgh, PA.
PURPOSE: Whereas gatifloxacin, a newer fluoroquinolone, was engineered to increase its Gram-positive potency, we assessed whether it still retained significant Gram-negative activity in vivo. Specifically, we compared the efficacy of Zymar (gatifloxacin 0.3%), Ciloxan (ciprofloxacin 0.3%), and fortified tobramycin (14 mg/mL) in the treatment of experimental Gram-negative bacterial infections of Serratia marcescens (SM) and Pseudomonas aeruginosa (PA) in the New Zealand White (NZW) rabbit keratitis model.
METHODS: A total of 30 NZW rabbits each were intrastromally inoculated in both eyes with approximately 1000 CFU of SM and PA. By E-test, the minimum inhibitory concentrations (MICs; mug/mL) for SM were gatifloxacin (0.125), ciprofloxacin (0.047), and tobramycin (1.5), and for PA were gatifloxacin (0.125), ciprofloxacin (0.19), and tobramycin (0.5). After 16 hours, the rabbits were divided into 4 treatment groups: (1) Zymar, (2) Ciloxan, (3) fortified tobramycin, and (4) saline control. One drop was instilled in both eyes every 15 minutes for 5 doses and then every 30 minutes for 14 doses. One hour after the final treatment, the animals were euthanized, and bacterial colony counts from the corneas were determined.
RESULTS: For SM, Zymar and Ciloxan significantly reduced the colony counts compared with tobramycin and saline control. Zymar was more effective than Ciloxan.For PA, all antibiotics reduced equivalently the colony counts compared with the saline control
CONCLUSIONS: The enhanced Gram-positive activity of gatifloxacin is not associated with any decreased Gram-negative activity in vivo. Zymar may prove useful for SM and PA keratitis.
PMID: 17525656 [PubMed - in process]
Saturday, May 19, 2007
Review article: the role of antibiotics vs. conventional pharmacotherapy in treating symptoms of irritable bowel syndrome.
Aliment Pharmacol Ther. 2007 Jun
Division of Gastroenterology and Hepatology, Weill Cornell Medical College of Cornell University, New York, NY, USA.
The concept of augmenting the management of irritable bowel syndrome with antibiotics is evolving, and many questions remain regarding this therapy relative to known and hypothesized irritable bowel syndrome pathophysiology. The clinical evidence of small intestinal bacterial overgrowth as an important aetiology of irritable bowel syndrome continues to accumulate. Clinical symptoms of bacterial overgrowth and irritable bowel syndrome are similar; however, a definitive cause-and-effect relationship remains unproven. It is unclear whether motility dysfunction causes bacterial overgrowth or gas products of enteric bacteria affect intestinal motility in irritable bowel syndrome.
To discusses the efficacy and tolerability of current symptom-directed pharmacotherapies and of antibiotics in the treatment of irritable bowel syndrome. Methods A computerized search of PubMed was performed with search terms 'IBS', 'pharmacotherapy' and 'antibiotics'. Relevant articles were selected, and the reference list of selected articles was reviewed to identify additional references.
Antibiotic treatment benefits a subset of irritable bowel syndrome patients. The non-absorbed antibiotic rifaximin has a favourable safety and tolerability profile compared with systemic antibiotics and demonstrates a therapeutic efficacy comparable with symptom-based irritable bowel syndrome pharmacotherapies.
Rifaximin is the only antibiotic with demonstrated sustained benefit beyond therapy cessation in irritable bowel syndrome patients in a placebo-controlled trial. Whether antibiotics can improve quality of life in patients with irritable bowel syndrome warrants further research.
PMID: 17509095 [PubMed - in process]
Friday, May 11, 2007
Fengycin antibiotics isolated from B-FS01 culture inhibit the growth of Fusarium moniliforme Sheldon ATCC 38932.
FEMS Microbiol Lett. 2007 May 8
College of Life Sciences, Nanjing Agricultural University, Nanjing, China.
Strain B-FS01, isolated from rape (Brassica napus) stem infected by Slerotinia sclerotiorum and identified as Bacillus subtilis, exhibited predominantly antagonistic activities against Fusarium moniliforme Sheldon ATCC 38932. Antifungal active compounds (AAC) were isolated and purified from the cultures of strain B-FS01 against ATCC 38932. The HPLC/electron spray ionization/collision-induced dissociation mass spectrum of AAC revealed a cluster of fengycin homologues containing fengycins A, fengycins B and a new type of fengycin. Further toxic assay of AAC in vitro against F. moniliforme indicated that AAC could strongly inhibit the growth of both mycelia and spores. In addition, treatment with AAC significantly modified the maize seed infection by ATCC 38932.
PMID: 17490402 [PubMed - as supplied by publisher]
Sunday, May 06, 2007
PLoS ONE. 2007 May
Department of Microbiology and Molecular Genetics, Department of Medicine and Pacific-Southwest Center for Biodefense and Emerging Infections, University of California Irvine, Irvine, California, United States of America.
BACKGROUND: The lone star tick Amblyomma americanum is a common pest and vector of infectious diseases for humans and other mammals in the southern and eastern United States. A Coxiella sp. bacterial endosymbiont was highly prevalent in both laboratory-reared and field-collected A. americanum. The Coxiella sp. was demonstrated in all stages of tick and in greatest densities in nymphs and adult females, while a Rickettsia sp. was less prevalent and in lower densities when present.
METHODOLOGY/PRINCIPAL FINDINGS: We manipulated the numbers of both bacterial species in laboratory-reared A. americanum by injecting engorged nymphs or engorged, mated females with single doses of an antibiotic (rifampin or tetracycline) or buffer alone. Burdens of the bacteria after molting or after oviposition were estimated by quantitative polymerase chain reaction with primers and probes specific for each bacterial species or, as an internal standard, the host tick. Post-molt adult ticks that had been treated with rifampin or tetracycline had lower numbers of the Coxiella sp. and Rickettsia sp. and generally weighed less than ticks that received buffer alone. Similarly, after oviposition, females treated previously with either antibiotic had lower burdens of both bacterial species in comparison to controls. Treatment of engorged females with either antibiotic was associated with prolonged time to oviposition, lower proportions of ticks that hatched, lower proportions of viable larvae among total larvae, and lower numbers of viable larvae per tick. These fitness estimators were associated with reduced numbers of the Coxiella sp. but not the Rickettsia sp.
CONCLUSION/SIGNIFICANCE: The findings indicate that the Coxiella sp. is a primary endosymbiont, perhaps provisioning the obligately hematophagous parasites with essential nutrients. The results also suggest that antibiotics could be incorporated into an integrated pest management plan for control of these and other tick vectors of disease.
PMID: 17476327 [PubMed - in process]
Tuesday, May 01, 2007
The Journal of Bone and Joint Surgery (American). 2007;89:929-933.doi:10.2106/JBJS.F.00919
An in Vivo Study Seth R. Yarboro, BS1, Elyse J. Baum, BS1 and Laurence E. Dahners, MD1
1 Department of Orthopaedics, University of North Carolina at Chapel Hill, CB 7055, Chapel Hill, NC 27599-7055. E-mail address for L.E. Dahners: firstname.lastname@example.org
Investigation performed at the University of North Carolina at Chapel Hill, Chapel Hill, North Carolina
Disclosure: In support of their research for or preparation of this work, one or more of the authors received, in any one year, outside funding or grants of less than $10,000 from the National Institute of Diabetes and Digestive and Kidney Diseases (NIDDK). Neither they nor a member of their immediate families received payments or other benefits or a commitment or agreement to provide such benefits from a commercial entity. No commercial entity paid or directed, or agreed to pay or direct, any benefits to any research fund, foundation, division, center, clinical practice, or other charitable or nonprofit organization with which the authors, or a member of their immediate families, are affiliated or associated.
A commentary is available with the electronic versions of this article, on our web site and on our quarterly CD-ROM (call our subscription department, at 781-449-9780, to order the CD-ROM).
Background: Currently, the standard for prophylaxis against surgical infection consists of perioperative systemic antibiotics. In this study, we investigated the relative efficacy of various methods of antibiotic delivery for the prevention of surgical wound infections. We hypothesized that sustained release of local antibiotics inside the wound cavity by a drug delivery system would be more effective than systemically administered antibiotics.
Methods: Using a rat model, we inoculated a surgical wound in the quadriceps muscle with 8.0 x 105 colony-forming units of Staphylococcus aureus and then administered one of seven types of treatment: no treatment (control), bacitracin irrigation, calcium sulfate flakes, systemic gentamicin, local aqueous gentamicin, local gentamicin-loaded calcium sulfate flakes, and a combination of local gentamicin-loaded calcium sulfate and systemic gentamicin. The seven treatment groups consisted of ten rats each. To further evaluate a trend, the group treated with systemic gentamicin and the one treated with local gentamicin solution were extended to include twenty-five and twenty-seven rats, respectively. At forty-eight hours postoperatively, specimens from the wounds were obtained for quantitative culture.
Results: The control group, the group treated with bacitracin irrigation, and the one treated with plain calcium sulfate had very high bacterial counts and high mortality rates while the groups treated with gentamicin had low bacterial counts and a 100% survival rate. Local gentamicin was significantly more effective than systemic gentamicin in reducing bacterial counts.
Conclusions: The gentamicin-loaded calcium sulfate flakes did not result in bacterial counts that were significantly lower than those following systemic administration of gentamicin, which refuted our hypothesis. However, gentamicin solution injected directly into the closed wound did result in levels of bacteria that were significantly lower than those following treatment with the systemic gentamicin.
Clinical Relevance: We believe that a high initial concentration of locally applied antibiotic inside the wound effectively kills bacteria present in the wound cavity, where systemic antibiotics have poor penetration, suggesting that this method of antibiotic administration may be a desirable adjunct for prophylaxis against infection in surgical wounds.The Journal of Bone and Joint Surgery (American)