Last data update: Apr 22, 2024. (Total: 46599 publications since 2009)
Records 1-21 (of 21 Records) |
Query Trace: Donlan R [original query] |
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Droplet rather than Aerosol Mediated Dispersion is the Primary Mechanism of Bacterial transmission from Contaminated Hand Washing Sink Traps (preprint)
Kotay S , Donlan RM , Ganim C , Barry K , Christensen BE , Mathers AJ . bioRxiv 2018 392431 An alarming rise in hospital outbreaks implicating hand-washing sinks has led to widespread acknowledgement that sinks are a major reservoir of antibiotic resistant pathogens in patient-care areas. An earlier study using a GFP-expressing Escherichia coli (GFP-E. coli) as a model organism demonstrated dispersal from drain biofilm in contaminated sinks. The present study further characterizes the dispersal of microorganisms from contaminated sinks. Replicate hand-washing sinks were inoculated with GFP-E. coli, and dispersion was measured using qualitative (settle plates) and quantitative (air sampling) methods. Dispersal caused by faucet water was captured with settle plates and air sampling methods when bacteria were present on the drain. In contrast, no dispersal was captured without or in between faucet events amending earlier theory that bacteria aerosolize from P-trap and disperse. Numbers of dispersed GFP-E. coli diminished substantially within 30 minutes after faucet usage, suggesting that the organisms were associated with larger droplet-sized particles that are not suspended in the air for long periods.IMPORTANCE Among the possible environmental reservoirs in a patient care environment, sink drains are increasingly recognized as potential reservoir of multidrug resistant healthcare-associated pathogens to hospitalized patients. With increasing antimicrobial resistance limiting therapeutic options for patients, better understanding of how pathogens disseminate from sink drains is urgently needed. Once this knowledge gap has decreased, interventions can be engineered to decrease or eliminate transmission from hospital sink drains to patients. The current study further defines the mechanisms of transmission for bacteria colonizing sink drains. |
Supplemental nutrients stimulate the amplification of carbapenemase-producing Klebsiella pneumoniae (CPKP) in a sink drain in vitro biofilm reactor model
Burgos-Garay ML , Santiago AJ , Kartforosh L , Kotay S , Donlan RM . Biofouling 2021 37 (5) 1-16 Liquid wastes (LW) disposed in hospital handwashing sinks may affect colonization of sink P-traps by carbapenemase-producing Klebsiella pneumoniae (CPKP), causing CPKP dispersal into the patient care environment. This study aimed to determine the effect of LW on biofilm formation and CPKP colonization in a P-Trap model (PTM). PTMs containing polymicrobial biofilms grown in autoclaved municipal tap water (ATW) supplemented with 5% dextrose in water (D5W), nutritional shake (Shake), sugar-based soft drink (Soda), or ATW were inoculated with K. pneumoniae ST258 KPC+ (ST258) or K. pneumoniae CAV1016 (CAV1016) and sampled after 7, 14, and 21 d. Biofilm bio-volume, mean thickness, and heterotrophic plate counts were significantly reduced and roughness coefficient significantly increased by Soda compared with D5W, Shake, or ATW. CPKP were significantly reduced by Soda but significantly amplified by D5W (ST258; CAV1016, 7 d) and Shake (ST258) suggesting that reducing LW disposal in sinks may reduce CPKP dispersal into patient care environments. |
Colonization of carbapenem-resistant Klebsiella pneumoniae in a sink-drain model biofilm system
Burgos-Garay M , Ganim C , de Man TJB , Davy T , Mathers AJ , Kotay S , Daniels J , Perry KA , Breaker E , Donlan RM . Infect Control Hosp Epidemiol 2020 42 (6) 1-9 BACKGROUND: Sink drains in healthcare facilities may provide an environment for antimicrobial-resistant microorganisms, including carbapenemase-producing Klebsiella pneumoniae (CPKP). METHODS: We investigated the colonization of a biofilm consortia by CPKP in a model system simulating a sink-drain P-trap. Centers for Disease Control (CDC) biofilm reactors (CBRs) were inoculated with microbial consortia originally recovered from 2 P-traps collected from separate patient rooms (designated rooms A and B) in a hospital. Biofilms were grown on stainless steel (SS) or polyvinyl chloride (PVC) coupons in autoclaved municipal drinking water (ATW) for 7 or 28 days. RESULTS: Microbial communities in model systems (designated CBR-A or CBR-B) were less diverse than communities in respective P-traps A and B, and they were primarily composed of β and γ Proteobacteria, as determined using 16S rRNA community analysis. Following biofilm development CBRs were inoculated with either K. pneumoniae ST45 (ie, strain CAV1016) or K. pneumoniae ST258 KPC+ (ie, strain 258), and samples were collected over 21 days. Under most conditions tested (CBR-A: SS, 7-day biofilm; CBR-A: PVC, 28-day biofilm; CBR-B: SS, 7-day and 28-day biofilm; CBR-B: PVC, 28-day biofilm) significantly higher numbers of CAV1016 were observed compared to 258. CAV1016 showed no significant difference in quantity or persistence based on biofilm age (7 days vs 28 days) or substratum type (SS vs PVC). However, counts of 258 were significantly higher on 28-day biofilms and on SS. CONCLUSIONS: These results suggest that CPKP persistence in P-trap biofilms may be strain specific or may be related to the type of P-trap material or age of the biofilm. |
Bacteriophage Infections of Biofilms of Health Care-Associated Pathogens: Klebsiella pneumoniae .
Santiago AJ , Donlan RM . EcoSal Plus 2020 9 (1) Members of the family Enterobacteriaceae, such as Klebsiella pneumoniae, are considered both serious and urgent public health threats. Biofilms formed by these health care-associated pathogens can lead to negative and costly health outcomes. The global spread of antibiotic resistance, coupled with increased tolerance to antimicrobial treatments in biofilm-associated bacteria, highlights the need for novel strategies to overcome treatment hurdles. Bacteriophages (phages), or viruses that infect bacteria, have reemerged as one such potential strategy. Virulent phages are capable of infecting and killing their bacterial hosts, in some cases producing depolymerases that are able to hydrolyze biofilms. Phage therapy does have its limitations, however, including potential narrow host ranges, development of bacterial resistance to infection, and the potential spread of phage-encoded virulence genes. That being said, advances in phage isolation, screening, and genome sequencing tools provide an upside in overcoming some of these limitations and open up the possibilities of using phages as effective biofilm control agents. |
A microbiological survey of handwashing sinks in the hospital built environment reveals differences in patient room and healthcare personnel sinks
Franco LC , Tanner W , Ganim C , Davy T , Edwards J , Donlan R . Sci Rep 2020 10 (1) 8234 Handwashing sinks and their associated premise plumbing are an ideal environment for pathogen-harboring biofilms to grow and spread throughout facilities due to the connected system of wastewater plumbing. This study was designed to understand the distribution of pathogens and antibiotic resistant organisms (ARO) within and among handwashing sinks in healthcare settings, using culture-dependent methods to quantify Pseudomonas aeruginosa, opportunistic pathogens capable of growth on a cefotaxime-containing medium (OPP-C), and carbapenem-resistant Enterobacteriaceae (CRE). Isolates from each medium identified as P. aeruginosa or Enterobacteriaceae were tested for susceptibility to aztreonam, ceftazidime, and meropenem; Enterobacteriaceae were also tested against ertapenem and cefotaxime. Isolates exhibiting resistance or intermediate resistance were designated ARO. Pathogens were quantified at different locations within handwashing sinks and compared in quantity and distribution between healthcare personnel (HCP) and patient room (PR) sinks. ARO were compared between samples within a sink (biofilm vs planktonic samples) and between sink types (HCP vs. PR). The drain cover was identified as a reservoir within multiple sinks that was often colonized by pathogens despite daily sink cleaning. P. aeruginosa and OPP-C mean log10 CFU/cm(2) counts were higher in p-trap and tail pipe biofilm samples from HCP compared to PR sinks (2.77 +/- 2.39 vs. 1.23 +/- 1.62 and 5.27 +/- 1.10 vs. 4.74 +/- 1.06) for P. aeruginosa and OPP-C, respectively. P. aeruginosa and OPP-C mean log10 CFU/ml counts were also higher (p < 0.05) in HCP compared to PR sinks p-trap water (2.21 +/- 1.52 vs. 0.89 +/- 1.44 and 3.87 +/- 0.78 vs. 3.21 +/- 1.11) for P. aeruginosa and OPP-C, respectively. However, a greater percentage of ARO were recovered from PR sinks compared to HCP sinks (p < 0.05) for Enterobacteriaceae (76.4 vs. 32.9%) and P. aeruginosa (25.6 vs. 0.3%). This study supports previous work citing that handwashing sinks are reservoirs for pathogens and ARO and identifies differences in pathogen and ARO quantities between HCP and PR sinks, despite the interconnected premise plumbing. |
Bacteriophage treatment of carbapenemase-producing Klebsiella pneumoniae in a multispecies biofilm: A potential biocontrol strategy for healthcare facilities
Santiago AJ , Burgos-Garay ML , Kartforosh L , Mazher M , Donlan RM . AIMS Microbiol 2020 6 (1) 43-63 The p-traps of hospital handwashing sinks represent a potential reservoir for antimicrobial-resistant organisms of major public health concern, such as carbapenemase-producing KPC+ Klebsiella pneumoniae (CPKP). Bacteriophages have reemerged as potential biocontrol agents, particularly against biofilm-associated, drug-resistant microorganisms. The primary objective of our study was to formulate a phage cocktail capable of targeting a CPKP strain (CAV1016) at different stages of colonization within polymicrobial drinking water biofilms using a CDC biofilm reactor (CBR) p-trap model. A cocktail of four CAV1016 phages, all exhibiting depolymerase activity, were isolated from untreated wastewater using standard methods. Biofilms containing Pseudomonas aeruginosa, Micrococcus luteus, Stenotrophomonas maltophilia, Elizabethkingia anophelis, Cupriavidus metallidurans, and Methylobacterium fujisawaense were established in the CBR p-trap model for a period of 28 d. Subsequently, CAV1016 was inoculated into the p-trap model and monitored over a period of 21 d. Biofilms were treated for 2 h at either 25 °C or 37 °C with the phage cocktail (109 PFU/ml) at 7, 14, and 21 d post-inoculation. The effect of phage treatment on the viability of biofilm-associated CAV1016 was determined by plate count on m-Endo LES agar. Biofilm heterotrophic plate counts (HPC) were determined using R2A agar. Phage titers were determined by plaque assay. Phage treatment reduced biofilm-associated CAV1016 viability by 1 log10 CFU/cm2 (p < 0.05) at 7 and 14 d (37 ℃) and 1.4 log10 and 1.6 log10 CFU/cm2 (p < 0.05) at 7 and 14 d, respectively (25 ℃). No significant reduction was observed at 21 d post-inoculation. Phage treatment had no significant effect on the biofilm HPCs (p > 0.05) at any time point or temperature. Supplementation with a non-ionic surfactant appears to enhance phage association within biofilms. The results of this study suggest the potential of phages to control CPKP and other carbapenemase-producing organisms associated with microbial biofilms in the healthcare environment. |
Droplet rather than aerosol mediated dispersion is the primary mechanism of bacterial transmission from contaminated hand washing sink traps
Kotay S , Donlan RM , Ganim C , Barry K , Christensen BE , Mathers AJ . Appl Environ Microbiol 2018 85 (2) An alarming rise in hospital outbreaks implicating hand-washing sinks has led to widespread acknowledgement that sinks are a major reservoir of antibiotic resistant pathogens in patient-care areas. An earlier study using a GFP-expressing Escherichia coli (GFP-E. coli) as a model organism demonstrated dispersal from drain biofilm in contaminated sinks. The present study further characterizes the dispersal of microorganisms from contaminated sinks. Replicate hand-washing sinks were inoculated with GFP-E. coli, and dispersion was measured using qualitative (settle plates) and quantitative (air sampling) methods. Dispersal caused by faucet water was captured with settle plates and air sampling methods when bacteria were present on the drain. In contrast, no dispersal was captured without or in between faucet events amending earlier theory that bacteria aerosolize from P-trap and disperse. Numbers of dispersed GFP-E. coli diminished substantially within 30 minutes after faucet usage, suggesting that the organisms were associated with larger droplet-sized particles that are not suspended in the air for long periods.IMPORTANCE Among the possible environmental reservoirs in a patient care environment, sink drains are increasingly recognized as potential reservoir of multidrug resistant healthcare-associated pathogens to hospitalized patients. With increasing antimicrobial resistance limiting therapeutic options for patients, better understanding of how pathogens disseminate from sink drains is urgently needed. Once this knowledge gap has decreased, interventions can be engineered to decrease or eliminate transmission from hospital sink drains to patients. The current study further defines the mechanisms of transmission for bacteria colonizing sink drains. |
Inhaled bacteriophage-loaded polymeric microparticles ameliorate acute lung infections
Agarwal R , Johnson CT , Imhoff BR , Donlan RM , McCarty NA , García AJ . Nat Biomed Eng 2018 2 (11) 1-5 Lung infections associated with pneumonia, or cystic fibrosis caused by Pseudomonas aeruginosa or other bacteria, result in significant morbidity and mortality, in part owing to the development of multidrug resistance, also against last-resort antibiotics. Lytic bacteriophages (that is, viruses that specifically kill bacteria) can reduce lung-associated infections, yet their clinical use is hindered by difficulties in delivering active phages to the deep lung. Here, we show that phage-loaded polymeric microparticles deposit throughout the lung via dry powder inhalation and that they deliver active phages. Phage-loaded microparticles effectively reduced P. aeruginosa infections and the associated inflammation in wild-type and cystic fibrosis transmembrane-conductance-regulator knockout mice, and rescued the mice from pneumonia-associated death. These polymeric microparticles might constitute a clinically translatable therapy for eradicating hospital-acquired lung infections and infections associated with cystic fibrosis. |
Hydrogel delivery of lysostaphin eliminates orthopedic implant infection by Staphylococcus aureus and supports fracture healing
Johnson CT , Wroe JA , Agarwal R , Martin KE , Guldberg RE , Donlan RM , Westblade LF , Garcia AJ . Proc Natl Acad Sci U S A 2018 115 (22) E4960-E4969 Orthopedic implant infections are a significant clinical problem, with current therapies limited to surgical debridement and systemic antibiotic regimens. Lysostaphin is a bacteriolytic enzyme with high antistaphylococcal activity. We engineered a lysostaphin-delivering injectable PEG hydrogel to treat Staphylococcus aureus infections in bone fractures. The injectable hydrogel formulation adheres to exposed tissue and fracture surfaces, ensuring efficient, local delivery of lysostaphin. Lysostaphin encapsulation within this synthetic hydrogel maintained enzyme stability and activity. Lysostaphin-delivering hydrogels exhibited enhanced antibiofilm activity compared with soluble lysostaphin. Lysostaphin-delivering hydrogels eradicated S. aureus infection and outperformed prophylactic antibiotic and soluble lysostaphin therapy in a murine model of femur fracture. Analysis of the local inflammatory response to infections treated with lysostaphin-delivering hydrogels revealed indistinguishable differences in cytokine secretion profiles compared with uninfected fractures, demonstrating clearance of bacteria and associated inflammation. Importantly, infected fractures treated with lysostaphin-delivering hydrogels fully healed by 5 wk with bone formation and mechanical properties equivalent to those of uninfected fractures, whereas fractures treated without the hydrogel carrier were equivalent to untreated infections. Finally, lysostaphin-delivering hydrogels eliminate methicillin-resistant S. aureus infections, supporting this therapy as an alternative to antibiotics. These results indicate that lysostaphin-delivering hydrogels effectively eliminate orthopedic S. aureus infections while simultaneously supporting fracture repair. |
Centers for Disease Control and Prevention Guideline for the Prevention of Surgical Site Infection, 2017
Berrios-Torres SI , Umscheid CA , Bratzler DW , Leas B , Stone EC , Kelz RR , Reinke CE , Morgan S , Solomkin JS , Mazuski JE , Dellinger EP , Itani KMF , Berbari EF , Segreti J , Parvizi J , Blanchard J , Allen G , Kluytmans Jajw , Donlan R , Schecter WP . JAMA Surg 2017 152 (8) 784-791 Importance: The human and financial costs of treating surgical site infections (SSIs) are increasing. The number of surgical procedures performed in the United States continues to rise, and surgical patients are initially seen with increasingly complex comorbidities. It is estimated that approximately half of SSIs are deemed preventable using evidence-based strategies. Objective: To provide new and updated evidence-based recommendations for the prevention of SSI. Evidence Review: A targeted systematic review of the literature was conducted in MEDLINE, EMBASE, CINAHL, and the Cochrane Library from 1998 through April 2014. A modified Grading of Recommendations, Assessment, Development, and Evaluation (GRADE) approach was used to assess the quality of evidence and the strength of the resulting recommendation and to provide explicit links between them. Of 5759 titles and abstracts screened, 896 underwent full-text review by 2 independent reviewers. After exclusions, 170 studies were extracted into evidence tables, appraised, and synthesized. Findings: Before surgery, patients should shower or bathe (full body) with soap (antimicrobial or nonantimicrobial) or an antiseptic agent on at least the night before the operative day. Antimicrobial prophylaxis should be administered only when indicated based on published clinical practice guidelines and timed such that a bactericidal concentration of the agents is established in the serum and tissues when the incision is made. In cesarean section procedures, antimicrobial prophylaxis should be administered before skin incision. Skin preparation in the operating room should be performed using an alcohol-based agent unless contraindicated. For clean and clean-contaminated procedures, additional prophylactic antimicrobial agent doses should not be administered after the surgical incision is closed in the operating room, even in the presence of a drain. Topical antimicrobial agents should not be applied to the surgical incision. During surgery, glycemic control should be implemented using blood glucose target levels less than 200 mg/dL, and normothermia should be maintained in all patients. Increased fraction of inspired oxygen should be administered during surgery and after extubation in the immediate postoperative period for patients with normal pulmonary function undergoing general anesthesia with endotracheal intubation. Transfusion of blood products should not be withheld from surgical patients as a means to prevent SSI. Conclusions and Relevance: This guideline is intended to provide new and updated evidence-based recommendations for the prevention of SSI and should be incorporated into comprehensive surgical quality improvement programs to improve patient safety. |
Book review: Microbial Biofilms, Second Edition
Donlan R . Emerg Infect Dis 2016 22 (6) 1142 Microbial Biofilms provides an overview of the formation, structure/architecture, cell-to-cell interactions, and dispersal of fungal and bacterial biofilms. The target audience is biofilm researchers, but this second edition of the book should also be useful for healthcare practitioners seeking a better understanding of microbial biofilms in healthcare delivery. | | The number of published papers pertaining to microbial biofilms in healthcare and public health has continued to grow since the publication of the first edition of Microbial Biofilms in 2004. For example, a search using PubMed for 2004–2016 identified 488 publications when using the search terms “biofilm and healthcare-associated infection” and 7,303 publications using the search terms “biofilm and public health,” compared to 73 and 1,459 publications, respectively, for 1992–2003. The current edition addresses this level of interest; several of the contributions in this book specifically focus on the role of biofilms in disease processes (Chapters 6, 7, 8, 14, and 19) or biofilm susceptibility to antimicrobial agents (Chapters 2 and 13). |
Virulence profile: Rodney Donlan
Donlan R . Virulence 2016 8 (1) 1-3 Following graduation from Virginia Tech with a B.S. in biology, it was my great fortune to be chosen to participate in a multinational, NSF-funded research project in Antarctica as an environmental monitor for the Dry Valley Drilling Project during the 1973–74 austral summer. My team leader was Frank Morelli, a seasoned microbiologist from the Cal Tech Jet Propulsion Laboratory and the Darwin Research Institute who had spent several field seasons in the Antarctic. I had limited training and experience in microbiology (a single four credit course in general microbiology and a summer work/study job in the clinical microbiology lab of the City of Norfolk, Virginia Department of Public Health). Under Frank's guidance and patient instruction, I quickly came up to speed and was given opportunities to travel from McMurdo Station to remote drilling sites in the Dry Valleys for several weeks at a time, collecting air, soil, and water samples to assess the environmental impact of drilling operations on these environmentally sensitive areas. During whatever free time I had I'd spend in the small McMurdo Biology Lab library, reading the scientific literature, trying to broaden my understanding of the geology and biology of the Antarctic Dry Valleys. My level of interest didn't go unnoticed and Frank suggested I take the next step in my career and consider graduate school in microbiology. I returned to Virginia Tech and spent the next three years (with another three-month interlude in Antarctica) working toward a Master's degree in microbiology. The microbiology faculty at Tech were outstanding, and my training was exceptional. I think I came away from this program with a solid foundation in microbiology, a great appreciation for the scientific literature, and a good understanding of experimental design. |
Bacteriophage-mediated control of a two-species biofilm of CAUTI-associated microorganisms in an in vitro urinary catheter model
Lehman SM , Donlan RM . Antimicrob Agents Chemother 2014 59 (2) 1127-37 Microorganisms from a patient or their environment may colonize indwelling urinary catheters, forming biofilm communities on catheter surfaces and increasing patient morbidity and mortality. This study investigated the effect of pre-treating hydrogel-coated silicone catheters with mixtures of Pseudomonas aeruginosa and Proteus mirabilis bacteriophages on the development of single- and two-species biofilms in a multi-day, continuous-flow in vitro model using artificial urine. Novel phages were purified from sewage, characterized, and screened for their ability to reduce biofilm development by clinical isolates of their respective hosts. Screening data showed that Artificial Urine Medium (AUM) is a valid substitute for human urine for the purpose of evaluating uropathogen biofilm control by these bacteriophages. Defined phage cocktails targeting each of P. aeruginosa and P. mirabilis were designed based on biofilm inhibition screens. Hydrogel-coated catheters were pre-treated with one or both cocktails and challenged with approximately 1x103 CFU/mL of the corresponding pathogen(s). Biofilm growth on catheter surfaces in AUM was monitored over 72 to 96 h. Phage pre-treatment reduced P. aeruginosa biofilm counts by 4 log10CFU/cm2 (p≤0.01) and P. mirabilis biofilm counts by > 2 log10 CFU/cm2 (p ≤0.01) over 48 h. The presence of P. mirabilis was always associated with an increase in lumen pH from 7.5 to 9.5, and with eventual blockage of the reactor lines. Results of this study suggest that pretreatment of a hydrogel urinary catheter with a phage cocktail can significantly reduce mixed species biofilm formation by clinically relevant bacteria. |
Bacteriophage K antimicrobial-lock technique for treatment of Staphylococcus aureus central venous catheter-related infection: a leporine model efficacy analysis
Lungren MP , Donlan RM , Kankotia R , Paxton BE , Falk I , Christensen D , Kim CY . J Vasc Interv Radiol 2014 25 (10) 1627-32 PURPOSE: To determine whether a bacteriophage antimicrobial-lock technique can reduce bacterial colonization and biofilm formation on indwelling central venous catheters in a rabbit model. MATERIALS AND METHODS: Cuffed central venous catheters were inserted into the jugular vein of female New Zealand White rabbits under image guidance. Catheters were inoculated for 24 hours with broth culture of methicillin-sensitive Staphylococcus aureus. The inoculum was aspirated, and rabbits were randomly assigned to two equal groups for 24 hours: (i) untreated controls (heparinized saline lock), (ii) bacteriophage antimicrobial-lock (staphylococcal bacteriophage K, propagated titer > 108/mL). Blood cultures were obtained via peripheral veins, and the catheters were removed for quantitative culture and scanning electron microscopy. RESULTS: Mean colony-forming units (CFU) per cm2 of the distal catheter segment, as a measure of biofilm, were significantly decreased in experimental animals compared with controls (control, 1.2 x 105 CFU/cm2; experimental, 7.6 x 103; P = .016). Scanning electron microscopy demonstrated that biofilms were present on the surface of five of five control catheters but only one of five treated catheters (P = .048). Blood culture results were not significantly different between the groups. CONCLUSIONS: In a rabbit model, treatment of infected central venous catheters with a bacteriophage antimicrobial-lock technique significantly reduced bacterial colonization and biofilm presence. Our data represent a preliminary step toward use of bacteriophage therapy for prevention and treatment of central venous catheter-associated infection. |
A new approach to mitigate biofilm formation on totally implantable venous access ports
Donlan RM . J Infect Dis 2014 210 (9) 1345-6 Use of intravascular catheters for patient care may be associated with increased risk of central line-associated bloodstream infections. It is estimated that up to 18 000 such infections occurred in intensive care units and up to 23 000 in inpatient wards of acute care hospitals in the United States in 2009 [1]. These device-associated infections result in significant morbidity, mortality, and costs of healthcare delivery in these patient populations. The infections result when microorganisms, introduced from the skin of the patient at the catheter insertion site, from a contaminated hub or needleless connector, or from hematogenous seeding, colonize the catheter and form a biofilm. The process of biofilm formation is initiated when microbial cells attach to the surfaces of the indwelling device. Microbial attachment is a complex process, affected by the chemical and physical characteristics of the substratum, host-produced conditioning films, hydrodynamics, characteristics of the aqueous medium, and properties of the microbial cell surface [2]. | A distinguishing characteristic of biofilms is the presence of an extracellular polymeric substance matrix, also known as the biofilm EPS (extracellular polymeric substance). The biofilm EPS matrix may be composed of polysaccharides, proteins, and extracellular DNA and may perform a number of important functions for the component organisms, including adhesion, aggregation, and protection from the host immune system and antimicrobial agents [3]. Inhibition of biofilm formation is preferred to eradication of an established biofilm because organisms rapidly develop tolerance to antimicrobial agents, a characteristic that worsens as the biofilm ages [4]. Biofilms on central venous catheters are difficult to eradicate, and for certain organisms (eg, Staphylococcus aureus), removal of the device may be the only option. |
Microbial biofilms on needleless connectors for central venous catheters: a comparison of standard and silver-coated devices collected from patients in an acute care hospital
Perez E , Williams M , Jacob JT , Reyes MD , Chernetsky Tejedor S , Steinberg JP , Rowe L , Ganakammal SR , Changayil S , Weil MR , Donlan RM . J Clin Microbiol 2013 52 (3) 823-31 Microorganisms may colonize needleless connectors (NCs) on intravascular catheters, forming biofilms and predisposing patients to catheter- associated infection (CAI). Standard and silver-coated NCs were collected from catheterized intensive care unit patients to characterize biofilm formation using culture-dependent and culture-independent methods and to investigate association between NC usage and biofilm characteristics. Viable microorganisms were detected by plate count (PC) from 46% of standard and 59% of silver-coated NCs (p=0.11). There were no significant associations (p>0.05, chi-squared test) between catheter type, side of catheter placement, number of catheter lumens, site of catheter placement, or NC duration, and positive NC. There was an association (p=0.04, chi-squared test) between infusion type and positive standard NCs. Viable microorganisms exhibiting intracellular esterase activity were detected on >90% of both NC types (p=0.751), suggesting that a large percentage of organisms were not culturable using the conditions provided in this study. Amplification of the 16S ribosomal RNA gene from selected NCs provided a substantially larger number of operational taxonomic units per NC than PC (26-43 vs 1-4), suggesting that culture-dependent methods may substantially underestimate microbial diversity on NCs. NC bacterial communities were clustered by patient and venous access type and may reflect the composition of the patient's local microbiome but may also contain organisms from the healthcare environment. NCs provide a portal of entry for a wide diversity of opportunistic pathogens to colonize the catheter lumen, forming a biofilm and increasing the potential for CAI, highlighting the importance of catheter maintenance practices to reduce microbial contamination. |
An in vitro evaluation of disinfection protocols used for needleless connectors of central venous catheters
Mazher MA , Kallen A , Edwards JR , Donlan RM . Lett Appl Microbiol 2013 57 (4) 282-7 A repeatable and sensitive method to evaluate the effect of three antiseptics and two disinfection techniques on viable microorganisms on luer-activated catheter needleless connectors (NCs) was developed. NCs were inoculated with Staphylococcus epidermidis or Klebsiella pneumoniae and disinfected with 3.15% chlorhexidine gluconate + 70% isopropanol (CGI), 70% isopropanol (IPA), or 10% PVP povidone iodine (PI) antiseptic pads using: a) scrubbing the NC septum and threaded external surfaces or b) wiping only the surface of the septum. Treatments were also evaluated against NCs pretreated with human serum and exposed for 18 hours to S. epidermidis prior to testing. Viable cells were quantified by plate count. The method for inoculation and recovery of luminal microorganisms was repeatable (SD, 0.31; n=28). IPA disinfection provided an approximate 3 log10 CFU reduction; CGI and PI provided 3 - 4 log10 reductions. PI and CGI were more effective than IPA (p<0.05), but differences between CGI and PI were not significant for either disinfection method. IPA, but not CGI and PI was also less effective (p<0.05) against NCs inoculated with K. pneumoniae than S. epidermidis. Pretreatment with serum and prolonged S. epidermidis inoculation removed the advantage seen with CGI and PI; log10 reductions were 1.80, 1.73, and 2.50 for CGI, PI, and IPA, respectively. PI or CGI may be more effective than IPA for NC disinfection but effectiveness may be reduced on NCs contaminated with blood or serum. (This article is protected by copyright. All rights reserved.) |
Bacteriophages are synergistic with bacterial interference for the prevention of Pseudomonas aeruginosa biofilm formation on urinary catheters
Liao KS , Lehman SM , Tweardy DJ , Donlan RM , Trautner BW . J Appl Microbiol 2012 113 (6) 1530-9 AIMS: We hypothesized that pretreating urinary catheters with benign Escherichia coli HU2117 plus an antipseudomonal bacteriophage (PhiE2005-A) would prevent Pseudomonas aeruginosa biofilm formation on catheters - a pivotal event in the pathogenesis of catheter-associated urinary tract infection (CAUTI). METHODS AND RESULTS: Silicone catheter segments were exposed to one of four pretreatments (sterile media; E. coli alone; phage alone; E. coli plus phage), inoculated with P. aeruginosa and then incubated up to 72 h in human urine before rinsing and sonicating to recover adherent bacteria. Pseudomonas aeruginosa adherence to catheters was almost 4 log(10) units lower when pretreated with E. coli plus phage compared to no pretreatment (P < 0.001) in 24-h experiments and more than 3 log(10) units lower in 72-h experiments (P < 0.05). Neither E. coli nor phage alone generated significant decreases. CONCLUSIONS: The combination of phages with a pre-established biofilm of E. coli HU2117 was synergistic in preventing catheter colonization by P. aeruginosa. SIGNIFICANCE AND IMPACT OF THE STUDY: We describe a synergistic protection against colonization of urinary catheters by a common uropathogen. Escherichia coli-coated catheters are in clinical trials; adding phage may offer additional benefit. |
Biofilm elimination on intravascular catheters: important considerations for the infectious disease practitioner
Donlan RM . Clin Infect Dis 2011 52 (8) 1038-45 The presence of biofilms on intravascular catheters and their role in catheter-related bloodstream infections is well accepted. The tolerance of catheter-associated biofilm organisms toward systemic antimicrobial treatments and the potential for development of antimicrobial resistance in the health care environment underscores the importance of alternative treatment strategies. Biofilms are microbial communities that exhibit unique characteristics that must be considered when evaluating the potential of biofilm prevention or control strategies. Because biofilm-associated infections do not respond consistently to therapeutically achievable concentrations of many antimicrobial agents, treatments that are more effective against slowly growing biofilm cells or combination treatments that can penetrate the biofilm matrix may be more effective. Alternative strategies that do not incorporate antimicrobial drugs have also been investigated. These approaches have the potential to prevent or eradicate biofilms on indwelling intravascular catheters and prevent or resolve catheter-related infections. |
Biofilm formation and effect of caspofungin on biofilm structure of Candida species bloodstream isolates
Ferreira JA , Carr JH , Starling CE , de Resende MA , Donlan RM . Antimicrob Agents Chemother 2009 53 (10) 4377-84 Candida biofilms are microbial communities, embedded in a polymeric matrix, growing attached to a surface, and are highly recalcitrant to antimicrobial therapy. These biofilms exhibit enhanced resistance against most antifungal agents except echinocandins and lipid formulations of amphotericin B. In this study, biofilm formation by different Candida species, particularly Candida albicans, C. tropicalis, and C. parapsilosis, was evaluated, and the effect of caspofungin (CAS) was assessed using a clinically relevant in vitro model system. CAS displayed in vitro activity against C. albicans and C. tropicalis cells within biofilms. Biofilm formation was evaluated after 48 h of antifungal drug exposure, and the effects of CAS on preformed Candida species biofilms were visualized using scanning electron microscopy (SEM). Several species-specific differences in the cellular morphologies associated with biofilms were observed. Our results confirmed the presence of paradoxical growth (PG) in C. albicans and C. tropicalis biofilms in the presence of high CAS concentrations. These findings were also confirmed by SEM analysis and were associated with the metabolic activity obtained by biofilm susceptibility testing. Importantly, these results suggest that the presence of atypical, enlarged, conical cells could be associated with PG and with tolerant cells in Candida species biofilm populations. The clinical implications of these findings are still unknown. |
Bacteriophage cocktail for the prevention of biofilm formation by Pseudomonas aeruginosa on catheters in an in vitro model system
Fu W , Forster T , Mayer O , Curtin JJ , Lehman SM , Donlan RM . Antimicrob Agents Chemother 2009 54 (1) 397-404 Microorganisms develop biofilms on indwelling medical devices and are associated with device-related infections, resulting in substantial morbidity and mortality. This study investigated the effect of pretreating hydrogel-coated catheters with Pseudomonas aeruginosa bacteriophages on biofilm formation by P. aeruginosa in an in vitro model. Hydrogel-coated catheters were exposed to a 10 log10 PFU ml(-1) lysate of P. aeruginosa phage M4 for 2 hours at 37 degrees C prior to bacterial inoculation. The mean viable biofilm count on untreated catheters was 6.87 log10 CFU cm(-2) after 24 h. Pretreatment of catheters with phage reduced this value to 4.03 log10 CFU cm(-2) (p<0.001). Phage treatment immediately following bacterial inoculation also reduced biofilm viable counts (4.37 log10 CFU cm(-2) reduction, p<0.001). Regrowth of biofilms on phage-treated catheters occurred between 24 and 48 h, but supplemental treatment with phage at 24 h significantly reduced biofilm regrowth (p<0.001). Biofilm isolates resistant to phage M4 were recovered from phage-pretreated catheters. Phage susceptibility profiles of these isolates were used to guide the development of a five-phage cocktail from a larger library of P. aeruginosa phages. Pretreatment of catheters with this cocktail reduced the 48 h mean biofilm cell density by 99.9% (from 7.13 log10 CFU cm(-2) to 4.13 log10 CFU cm(-2), p<0.001), but fewer biofilm isolates were resistant to these phages. These results suggest the potential of applying phages, especially phage cocktails to the surfaces of indwelling medical devices for mitigating biofilm formation by clinically relevant bacteria. |
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