Merle E Olson

Publications (27)89.24 Total impact

• Article: Microtiter susceptibility testing of microbes growing on peg lids: a miniaturized biofilm model for high-throughput screening.

  Joe J Harrison, Carol A Stremick, Raymond J Turner, Nick D Allan, Merle E Olson, Howard Ceri
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  ABSTRACT: Batch culture of biofilms on peg lids is a versatile method that can be used for microtiter determinations of biofilm antimicrobial susceptibility. In this paper, we describe a core protocol and a set of parameters (surface composition, the rate of rocking or orbital motion, temperature, cultivation time, inoculum size, atmospheric gases and nutritional medium) that can be adjusted to grow single- or multispecies biofilms on peg surfaces. Mature biofilms formed on peg lids can then be fitted into microtiter plates containing test agents. After a suitable exposure time, biofilm cells are disrupted into a recovery medium using sonication. Microbicidal endpoints can be determined qualitatively using optical density measurements or quantitatively using viable cell counting. Once equipment is calibrated and growth conditions are at an optimum, the procedure requires approximately 5 h of work over 4-6 d. This efficient method allows antimicrobial agents and exposure conditions to be tested against biofilms on a high-throughput scale.
  Nature Protocol 07/2010; 5(7):1236-54. · 8.36 Impact Factor
• Article: Needed, new paradigms in antibiotic development.

  Howard Ceri, Merle E Olson, Raymond J Turner
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  ABSTRACT: While antibiotic resistance has grabbed the headlines and the attention of the pharmaceutical industry, the lack of susceptibility of biofilms formed both on animate and inanimate surfaces deserve greater attention from the industry, medical practitioners and regulators. The current literature tells us that the inherent tolerance to antibiotics demonstrated by antibiotic-sensitive organisms when grown as a biofilm clearly identifies a major disconnect between our current practices in antimicrobial development, diagnostics and efficacy in patient treatment. A paradigm shift is required in the way we utilize conventional antimicrobials and in the way we screen for next-generation antibiotics with efficacy to treat biofilms associated with chronic, recurrent and device related infections. This paradigm shift must not only take place in industry but also in how drugs are brought to the marketplace for acceptance.
  Expert Opinion on Pharmacotherapy 04/2010; 11(8):1233-7. · 3.20 Impact Factor
• Article: Activity of a silver-coated endotracheal tube in preclinical models of ventilator-associated pneumonia and a study after extubation.

  Jordi Rello, Bekele Afessa, Antonio Anzueto, Alejandro C Arroliga, Merle E Olson, Marcos I Restrepo, Silke S Talsma, Ronald L Bracken, Marin H Kollef
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  ABSTRACT: To elucidate the mechanism of action of the silver-coated endotracheal tube in models of the early pathogenesis of ventilator-associated pneumonia. Open-labeled, prospective, controlled, sequentially conducted, preclinical studies, and in vitro assessment of tubes from patients. Microbiology laboratory of a device manufacturer, animal research facility of a university, and a tertiary medical center. Endotracheal tubes were similar except for the silver coating. In the 21-day in vitro elution model, tube samples were incubated in saline solution at 37.8 degrees C. In the in vitro adherence model, coated and uncoated tubes were exposed to 21 respiratory isolates of radiolabeled microorganisms for 2-4 hrs. In the animal model, 12 healthy white rabbits were intubated for 16 hrs with noncuffed silver-coated or uncoated tubes and challenged with buccal administration of Pseudomonas aeruginosa. In the in vitro assessment, tubes from 16 patients underwent quantitative culture assessment and qualitative confocal laser scanning microscopy. After in vitro incubation, the mean residual silver concentration was 2.6 microg/cm, confirming that the coating was not entirely depleted. In vitro adherence to the silver-coated endotracheal tube was less than that of the uncoated tube for 12 of 21 isolates and equivalent for seven. For example, adherence to the silver-coated endotracheal tube was reduced >90% for all five isolates of P. aeruginosa (p < .05). In rabbits, P. aeruginosa colonization on the silver-coated endotracheal tube was reduced 99.9% compared with that on the uncoated tube (p < .0001); colonization in the tracheal and lung tissue was reduced > or =99% (p < .05). In the in vitro assessment, pathogens were detected on none of nine silver-coated tubes from patients and three of seven control tubes (p > .05). : The collective findings of this series of studies demonstrated that the silver-coated endotracheal tube was active in models designed to mimic the early pathogenesis of ventilator-associated pneumonia.
  Critical care medicine 04/2010; 38(4):1135-40. · 6.37 Impact Factor
• Article: Can filamentous fungi form biofilms?

  Michael W Harding, Lyriam L R Marques, Ronald J Howard, Merle E Olson
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  ABSTRACT: The discovery of biofilm formation in bacteria and yeasts has led to a better understanding of microbial ecology and to new insights into the mechanisms of virulence and persistence of pathogenic microorganisms. However, it is generally assumed that filamentous fungi, some of which have a significant impact on our health or our economy, do not form biofilms. In contrast to this assumption, here we discuss recent findings supporting the hypothesis that surface-associated filamentous fungi can form biofilms. Based on these findings and on previous models for bacterial and yeast systems, we propose preliminary criteria and a model for biofilm formation by filamentous fungi.
  Trends in Microbiology 11/2009; 17(11):475-80. · 7.91 Impact Factor
• Source

  Available from: uleth.ca

  Article: The molecular epidemiology of Cryptosporidium and Giardia infections in coyotes from Alberta, Canada, and observations on some cohabiting parasites.

  R C Andrew Thompson, Doug D Colwell, Todd Shury, Amber J Appelbee, Carolyn Read, Zablon Njiru, Merle E Olson
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  ABSTRACT: Coyotes from southern Alberta and Saskatchewan, Canada, were examined for the presence of Giardia and Cryptosporidium and cohabiting helminths. Toxascaris was present in over 90% of the 70 animals examined, and Taenia sp. in 6.5-25% of the two groups of animals studied. Giardia (12.5-21.7%) and Cryptosporidium (0-17.4%) were also common and molecular characterisation revealed both zoonotic and host-adapted genotypes of Giardia, whereas the Cryptosporidium proved to be a variant of the canine species C. canis. The seasonal variation observed in the occurrence of Cryptosporidium may be related to stress-induced shedding of the parasite.
  Veterinary Parasitology 11/2008; 159(2):167-70. · 2.58 Impact Factor
• Article: Copper and quaternary ammonium cations exert synergistic bactericidal and antibiofilm activity against Pseudomonas aeruginosa.

  Joe J Harrison, Raymond J Turner, Daniel A Joo, Michelle A Stan, Catherine S Chan, Nick D Allan, Helen A Vrionis, Merle E Olson, Howard Ceri
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  ABSTRACT: Biofilms are slimy aggregates of microbes that are likely responsible for many chronic infections as well as for contamination of clinical and industrial environments. Pseudomonas aeruginosa is a prevalent hospital pathogen that is well known for its ability to form biofilms that are recalcitrant to many different antimicrobial treatments. We have devised a high-throughput method for testing combinations of antimicrobials for synergistic activity against biofilms, including those formed by P. aeruginosa. This approach was used to look for changes in biofilm susceptibility to various biocides when these agents were combined with metal ions. This process identified that Cu(2+) works synergistically with quaternary ammonium compounds (QACs; specifically benzalkonium chloride, cetalkonium chloride, cetylpyridinium chloride, myristalkonium chloride, and Polycide) to kill P. aeruginosa biofilms. In some cases, adding Cu(2+) to QACs resulted in a 128-fold decrease in the biofilm minimum bactericidal concentration compared to that for single-agent treatments. In combination, these agents retained broad-spectrum antimicrobial activity that also eradicated biofilms of Escherichia coli, Staphylococcus aureus, Salmonella enterica serovar Cholerasuis, and Pseudomonas fluorescens. To investigate the mechanism of action, isothermal titration calorimetry was used to show that Cu(2+) and QACs do not interact in aqueous solutions, suggesting that each agent exerts microbiological toxicity through independent biochemical routes. Additionally, Cu(2+) and QACs, both alone and in combination, reduced the activity of nitrate reductases, which are enzymes that are important for normal biofilm growth. Collectively, the results of this study indicate that Cu(2+) and QACs are effective combinations of antimicrobials that may be used to kill bacterial biofilms.
  Antimicrobial Agents and Chemotherapy 08/2008; 52(8):2870-81. · 4.84 Impact Factor
• Article: The GacS sensor kinase controls phenotypic reversion of small colony variants isolated from biofilms of Pseudomonas aeruginosa PA14.

  James A Davies, Joe J Harrison, Lyriam L R Marques, Ginevra R Foglia, Carol A Stremick, Douglas G Storey, Raymond J Turner, Merle E Olson, Howard Ceri
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  ABSTRACT: The GacS/GacA two-component regulatory system in pseudomonads regulates genes involved in virulence, secondary metabolism and biofilm formation. Despite these regulatory functions, some Pseudomonas species are prone to spontaneous inactivating mutations in gacA and gacS. A gacS(-) strain of Pseudomonas aeruginosa PA14 was constructed to study the physiological role of this sensor histidine kinase. This loss-of-function mutation was associated with hypermotility, reduced production of acylhomoserine lactones, impaired biofilm maturation, and decreased antimicrobial resistance. Biofilms of the gacS(-) mutant gave rise to phenotypically stable small colony variants (SCVs) with increasing frequency when exposed to silver cations, hydrogen peroxide, human serum, or certain antibiotics (tobramicin, amikacin, azetronam, ceftrioxone, oxacilin, piperacillin or rifampicin). When cultured, the SCV produced thicker biofilms with greater cell density and greater antimicrobial resistance than did the wild-type or parental gacS(-) strains. Similar to other colony morphology variants described in the literature, this SCV was less motile than the wild-type strain and autoaggregated in broth culture. Complementation with gacS in trans restored the ability of the SCV to revert to a normal colony morphotype. These findings indicate that mutation of gacS is associated with the occurrence of stress-resistant SCV cells in P. aeruginosa biofilms and suggests that in some instances GacS may be necessary for reversion of these variants to a wild-type state.
  FEMS Microbiology Ecology 02/2007; 59(1):32-46. · 3.41 Impact Factor
• Article: Giardiasis and cryptosporidiosis in ruminants.

  Ryan M O'Handley, Merle E Olson
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  ABSTRACT: Although they differ considerably with respect to their biology, both Giardia duodenalis and Cryptosporidium parvum are common in ruminants, whereas Cryptosporidium andersoni is not. G. duodenalis infections are acquired during the first few months of life, tend to be chronic, and may be a production-limiting disease of ruminants. C. parvum infections remain an important cause of diarrhea in neonatal ruminants. Abomasal cryptosporidiosis, caused by C. andersoni, is an emerging disease of cattle that may affect both beef and dairy herds. This article reviews the life cycles, production impacts, treatments, controls, and zoonotic potentials of these important ruminant parasites.
  Veterinary Clinics of North America Food Animal Practice 12/2006; 22(3):623-43. · 1.47 Impact Factor
• Article: Cytokine and growth factor mRNA expression patterns associated with the hypercontracted, hyperpigmented healing phenotype of red duroc pigs: a model of abnormal human scar development?

  Corrie L Gallant-Behm, Merle E Olson, David A Hart
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  ABSTRACT: Skin wounds in red Duroc pigs heal with the formation of hypercontractile, hyperpigmented scars, similar in some respects to human hypertrophic scars. The goal of this study was to characterize the mRNA expression patterns for a subset of relevant cytokines, growth factors, receptors, and transcription factors involved in the red Duroc scarring phenotype. Full-thickness and deep dermal wounds were created on the backs of juvenile female red Duroc pigs. Samples were taken every two weeks postwounding and total RNA and DNA were extracted and quantified. RT-PCR was performed using porcine gene-specific primers for 15 relevant molecules. The majority of molecules examined exhibited a biphasic pattern of expression, with peaks of expression at days 14 and 56 postinjury. The molecular expression pattern observed correlates well with the gross healing phenotype and matrix molecule expression patterns previously reported in red Duroc pigs. These findings enhance our understanding of the processes associated with fibroproliferative scar-formation.
  Journal of Cutaneous Maedicine and Surgery 09/2005; 9(4):165-77. · 0.98 Impact Factor
• Article: Giardia and Cryptosporidium in mammalian wildlife--current status and future needs.

  Amber J Appelbee, R C Andrew Thompson, Merle E Olson
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  ABSTRACT: Environmental pollution with human and domestic-animal fecal material is recognized as a potential pathogen pathway for wildlife infections with zooanthropomorphic protozoan parasites such as Giardia and Cryptosporidium. In this article, we review current knowledge about the diversity of free-living and captive terrestrial and marine mammalian wildlife species infected with Giardia and Cryptosporidium. The combination of prevalence studies with modern molecular-genotyping techniques is providing valuable insights into the host specificity and possible transmission routes of these two important parasites.
  Trends in Parasitology 09/2005; 21(8):370-6. · 5.14 Impact Factor
• Article: Comparison of in vitro disc diffusion and time kill‐kinetic assays for the evaluation of antimicrobial wound dressing efficacy

  Corrie L. Gallant‐Behm, Hua Q. Yin, Shijie Liu, John P. Heggers, Rita E. Langford, Merle E. Olson, David A. Hart, Robert E Burrell PhD
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  ABSTRACT: There is a plethora of new silver-containing dressings on the market today. Various manufacturers attempt to show that their dressings are the most efficacious and therefore should be preferentially employed by health care workers based on the results of their in vitro tests. However, there have been no studies that clearly identify which tests are appropriate for comparison purposes. The purpose of this study was to determine which in vitro test is most appropriate for evaluating the antimicrobial efficacy of silver-containing dressings. This was done by testing seven silver-containing dressings and two non-silver-containing topical agents against 17 clinically relevant microorganisms using zone of inhibition assays and time-kill kinetic assays in complex media. The results for the two assays were then correlated to determine whether the methods generated similar results. It was determined that the two methods do not correlate at all. This is most likely a result of the silver interacting with the media in the zone of inhibition test, thus invalidating the results of this test. We therefore conclude that zone of inhibition data generated for silver-containing dressings is of little value when assessing antimicrobial efficacy and that time-kill assays are of greater use.
  Wound Repair and Regeneration 06/2005; 13(4):412 - 421. · 2.91 Impact Factor
• Article: Prevalence of Giardia and Cryptosporidium in beef cows in southern Ontario and in beef calves in southern British Columbia.

  Tim A McAllister, Merle E Olson, Andy Fletch, Merv Wetzstein, Toby Entz
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  ABSTRACT: In 1998 and 1999, fecal samples were collected from 669 beef cows on 39 farms located within 10 counties of Ontario. Overall prevalences of Giardia, Cryptosporidium muris, and Cryptosporidium parvum in cows were 8.7%, 10.6%, and 18.4%, respectively. Of the 39 farms sampled, Giardia was detected on 64%, Cr. muris on 72%, and Cr. parvum on 90%. Cryptosporidium parvum was detected in 28% of the cows in 1998 and in 5.2% in 1999. Differences between the 2 y were attributed to sampling during calving in 1998 and during gestation in 1999. In 1998, Giardia, Cr. muris, and Cr. parvum were detected in herds provided with municipal water. In 1998, 193 calves were sampled from 10 farms, representing 4 watersheds, in British Columbia. Thirty-six percent of the calves exhibited signs of diarrhea. Overall prevalences of Giardia and Cryptosporidium spp. in calves were 36% and 13%, respectively. There was evidence that calves with Giardia were more likely to develop scours. Restricting cattle from surface water during periods of high shedding may reduce watershed contamination.
  The Canadian veterinary journal. La revue veterinaire canadienne 02/2005; 46(1):47-55. · 1.06 Impact Factor
• Article: Update on Cryptosporidium and Giardia infections in cattle.

  Merle E Olson, Ryan M O'Handley, Brenda J Ralston, Timothy A McAllister, R C Andrew Thompson
  Trends in Parasitology 05/2004; 20(4):185-91. · 5.14 Impact Factor
• Source

  Available from: ncbi.nlm.nih.gov

  Article: Biofilm formation by group a streptococci: is there a relationship with treatment failure?

  Joslyn Conley, Merle E Olson, Linda S Cook, Howard Ceri, Van Phan, H Dele Davies
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  ABSTRACT: Group A streptococcus (GAS) is the primary cause of bacterial pharyngitis in children and adults. Up to one-third of patients treated for GAS pharyngitis fail to respond to antibiotic therapy. The objective of this cohort study was to evaluate GAS biofilm formation as a mechanism for antibiotic treatment failure using previously collected GAS isolates and penicillin treatment outcome data. The minimum biofilm eradication concentration (MBEC) assay device was used to determine the biofilm-forming capabilities, efficiencies, and antibiotic susceptibilities of GAS isolates. The MBECs and MICs of several antibiotics for GAS were determined. All 99 GAS isolates available for this study formed biofilms, with various efficiencies. Antibiotic MBECs were consistently higher than MICs for all of the GAS isolates. MBECs indicated penicillin insensitivity in 60% of GAS isolates, producing the first report of in vitro GAS insensitivity to penicillin. Using MBECs to predict penicillin treatment failure had better sensitivity (56%) but lower specificity (36%) than the sensitivity (0%) and specificity (100%) when MICs were used. However, the positive predictive value of the MBEC was superior to that of the MIC (56 versus 0%), while the negative predictive values (42 and 47%) were similar. More studies are needed to understand the roles of biofilms and the MBEC assay in predicting GAS treatment failure. In addition, further investigations are necessary to determine if non-biofilm-forming strains of GAS exist and the roles of in vivo monospecies and multispecies biofilms in streptococcal pharyngitis treatment failure.
  Journal of Clinical Microbiology 10/2003; 41(9):4043-8. · 4.15 Impact Factor
• Article: Prevalence and infection pattern of naturally acquired giardiasis and cryptosporidiosis in range beef calves and their dams.

  Brenda J Ralston, Tim A McAllister, Merle E Olson
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  ABSTRACT: The prevalence and infection pattern of naturally acquired giardiasis and cryptosporidiosis in 20 ranch raised beef calves and their dams from birth to weaning was determined. Rectal fecal samples were collected from calves at 3 days of age and weekly thereafter; cows' fecal samples were collected at the time of calving, 1 week later and four times during the summer grazing period. Blood samples were collected from the calves at 3 days of age to determine IgG(1) concentrations. Giardia lamblia cysts were shed by all 20 calves (100%) at some date during the duration of the study. However, only one calf (5%) shed Cryptosporidium parvum on two sample dates during the trial. Giardia cysts were first detected at 3.9+/-1.37 weeks of age with a range of 2-7 weeks of age. The geometric mean number of Giardia cysts in the calf feces increased from none at 1 week of age to a maximum of 2230 cysts/g of feces at 5 weeks of age and then decreased to 2 cysts/g at 25-27 weeks of age. Infection rate of calves shedding Giardia cysts peaked at 85% at 5 weeks of age and then decreased to 21% at 25-27 weeks of age. Giardia cysts, shed by calves peaked 1 week after initial shedding and decreased (P<0.05) for the remainder of the trial with the exception of week 3. There was a lower (P<0.05) percentage of calves shedding Giardia cysts weeks 3-10 and 15-25 compared to when shedding was first detected. All calves had complete or partial transfer of passive immunity as measured by IgG(1) levels. The rate of infection (15%) and the geometric mean number of Giardia cysts in the cows' feces (38.49 cysts/g) numerically increased at 1 week post-calving compared to levels at calving. The rate of infection (40%) numerically increased and the geometric mean number of Cryptosporidium andersoni oocysts in the cow feces (37.48 oocysts/g) increased (P<0.05) at 1 week post-calving and decreased to 0 at 13-16 weeks post-calving. This study is the first to document the cumulative prevalence and infection patterns of Giardia and Cryptosporidium in beef cattle under ranch conditions.
  Veterinary Parasitology 06/2003; 114(2):113-22. · 2.58 Impact Factor
• Article: Passive immunity and serological immune response in dairy calves associated with natural Giardia duodenalis infections.

  Ryan M O'Handley, Howard Ceri, Colleen Anette, Merle E Olson
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  ABSTRACT: In a previous study, Giardia infection patterns were studied in newborn dairy calves over a 4-month period. Chronic Giardia infections were observed in all calves with initial cyst excretion occurring at approximately 1 month of age. In the work presented here, the passive immunity and serological immune response associated with these Giardia infections were examined. Colostrum and milk samples were collected from the dams of these calves, and monthly serum samples were collected from each calf. The colostrum, milk and sera samples were analyzed by ELISA and Western blot for the presence of anti-Giardia IgG antibodies. In addition, the in vitro anti-Giardia activity of milk and colostrum was examined using a miniculture adherence assay. When examined by ELISA, mean anti-Giardia antibody titres were found to be significantly higher in colostrum compared to milk. The monthly mean serum antibody titres in the calves were not found to differ significantly at any time point during the study. Western blot analysis revealed that colostrum from the dams reacted strongly with many different Giardia antigens between 205 and 7.5kDa, while milk reacted with few antigens in the same size range. Sera collected from the calves when 30 and 60 days of age reacted with few Giardia antigens, but as the calves aged, IgG antibodies in their sera began to react with antigens of 21, 50, 65, 73 and 79kDa. The miniculture adherence assay demonstrated that colostrum had significantly more anti-Giardia activity in vitro compared to milk. These results suggest that the calves in this dairy did not mount a significant humoral immune response against Giardia following infection. However, colostrum contained a high level of anti-Giardia antibodies and exhibited anti-Giardia activity in vitro. Therefore, colostrum may have the potential to provide initial protection against Giardia infections in calves, but the lack of a strong, specific humoral immune response by these calves could account for the high prevalence and chronic duration of the infections.
  Veterinary Parasitology 05/2003; 113(2):89-98. · 2.58 Impact Factor
• Article: Biofilm formation and biocide susceptibility testing of Mycobacterium fortuitum and Mycobacterium marinum.

  Elias Bardouniotis, Howard Ceri, Merle E Olson
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  ABSTRACT: The ability of non-tuberculous mycobacteria to form biofilms may allow for their increased resistance to currently used biocides in medical and industrial settings. This study examines the biofilm growth of Mycobacterium fortuitum and Mycobacterium marinum, using the MBEC trade mark assay system, and compares the susceptibility of planktonic and biofilm cells to commercially available biocides. With scanning electron microscopy, both M. fortuitum and M. marinum form biofilms that are morphologically distinct. Biocide susceptibility testing suggested that M. fortuitum biofilms displayed increased resistance over their planktonic state. This is contrasted with M. marinum biofilms, which were generally as or more susceptible over their planktonic state.
  Current Microbiology 02/2003; 46(1):28-32. · 1.82 Impact Factor
• Source

  Available from: ncbi.nlm.nih.gov

  Article: Biofilm bacteria: formation and comparative susceptibility to antibiotics.

  Merle E Olson, Howard Ceri, Douglas W Morck, Andre G Buret, Ronald R Read
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  ABSTRACT: The Calgary Biofilm Device (CBD) was used to form bacterial biofilms of selected veterinary gram-negative and gram-positive pathogenic bacteria from cattle, sheep, pigs, chicken, and turkeys. The minimum inhibitory concentration (MIC) and minimum biofilm eradication concentration (MBEC) of ampicillin, ceftiofur, cloxacillin, oxytetracycline, penicillin G, streptomycin, tetracycline, enrofloxacin, erythromycin, gentamicin, tilmicosin, and trimethoprim-sulfadoxine for gram-positive and -negative bacteria were determined. Bacterial biofilms were readily formed on the CBD under selected conditions. The biofilms consisted of micro-colonies encased in extracellular polysaccharide material. Biofilms composed of Arcanobacterium (Actinomyces) pyogenes, Staphylococcus aureus, Staphylococcus hyicus, Streptococcus agalactiae, Corynebacterium renale, or Corynebacterium pseudotuberculosis were not killed by the antibiotics tested but as planktonic bacteria they were sensitive at low concentrations. Biofilm and planktonic Streptococcus dysgalactiae and Streptococcus suis were sensitive to penicillin, ceftiofur, cloxacillin, ampicillin, and oxytetracycline. Planktonic Escherichia coli were sensitive to enrofloxacin, gentamicin, oxytetracycline and trimethoprim/ sulfadoxine. Enrofloxacin and gentamicin were the most effective antibiotics against E. coli growing as a biofilm. Salmonella spp. and Pseudomonas aeruginosa isolates growing as planktonic populations were sensitive to enrofloxacin, gentamicin, ampicillin, oxytetracycline, and trimethoprim/sulfadoxine, but as a biofilm, these bacteria were only sensitive to enrofloxacin. Planktonic and biofilm Pasteurella multocida and Mannheimia haemolytica had similar antibiotic sensitivity profiles and were sensitive to most of the antibiotics tested. The CBD provides a valuable new technology that can be used to select antibiotics that are able to kill bacteria growing as biofilms.
  Canadian journal of veterinary research = Revue canadienne de recherche vétérinaire 05/2002; 66(2):86-92. · 0.94 Impact Factor
• Article: An improved polymerase chain reaction assay for the detection of Tritrichomonas foetus in cattle.

  D Douglas Nickel, Merle E Olson, Gilbert A Schultz
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  ABSTRACT: An improved polymerase chain reaction test has been developed to detect Tritrichomonas foetus, the causative agent of trichomoniasis in cattle. The test amplifies a region of the 5.8S ribosomal RNA gene of T. foetus, and it is simple, sensitive, and specific when compared with traditional methods to examine field samples.
  The Canadian veterinary journal. La revue veterinaire canadienne 04/2002; 43(3):213-6. · 1.06 Impact Factor
• Article: Silver-coated endotracheal tubes associated with reduced bacterial burden in the lungs of mechanically ventilated dogs.

  Merle E Olson, Barry G Harmon, Marin H Kollef
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  ABSTRACT: To evaluate the influence of silver-coated endotracheal tubes on the lung bacterial burden of mechanically ventilated dogs. Randomized, double-blinded, controlled experiment. Animal research facility of a regional medical university. Eleven healthy adult dogs. The dogs were intubated either with cuffed, noncoated endotracheal tubes or with endotracheal tubes having a novel antimicrobial silver hydrogel coating and were challenged with buccal administration of Pseudomonas aeruginosa. The silver coating delayed the appearance of bacteria on the inner surface of the endotracheal tubes ([mean +/- SD] duration of mechanical ventilation before appearance of bacteria, 3.2 +/- 0.8 days; mean duration of mechanical ventilation, 1.8 +/- 0.4 days; p = 0.016). The mean total aerobic bacterial burden in the lung parenchyma was statistically lower among the dogs receiving the silver-coated endotracheal tubes compared to those not receiving them (4.8 +/- 0.8 vs 5.4 +/- 9 log cfu/g lung tissue, respectively; p = 0.010). Pronounced differences were seen in the gross and histologic assessments of inflammation in the lung. Using an increasing severity scale of 0 to 12 to assess four components of histology (ie, hyperemia, edema, cellular infiltration, and bacterial presence), dogs receiving noncoated endotracheal tubes had statistically greater histology scores compared to dogs receiving silver-coated endotracheal tubes (7.1 plus minus 1.6 vs 2.8 plus minus 1.2, respectively; p < 0.001). These results suggest that the silver coating of endotracheal tubes may delay the onset of and decrease the severity of lung colonization by aerobic bacteria. Based on these results, clinical studies are planned to determine the safety and clinical efficacy of silver-coated endotracheal tubes in patients requiring mechanical ventilation in the ICU setting.
  Chest 03/2002; 121(3):863-70. · 5.25 Impact Factor