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Biofilms on Medical Devices
Silke S. Talsma, Ph.D. C.R. Bard, Inc.
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Outline The biofilm problem Antibiotic resistance
Biofilm on urinary catheters Biofilm on endotracheal tubes
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The Biofilm Problem
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Biofilms are everywhere
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Diseases caused by biofilm
Device related infections Cystic fibrosis Plaque; Gingivitis Ear infection Bacterial endocarditis Chronic prostatitis The Centers for Disease Control and the National Institutes of Health estimate that 65% to 80% of all chronic infections can be attributed to microbial biofilms.
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What is a biofilm? A collection of microorganisms on a surface that is surrounded by an extracellular matrix made up of primarily polysaccharide materials
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Stages of Biofilm Formation
Bacteria switch from a free-floating (planktonic) state where they function as individuals to a sessile state where they function as communities
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Biofilms move along the extraluminal or intraluminal surface of medical devices
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A closer look at biofilms Extracellular Matrix
Microorganisms in biofilms are surrounded by a protective extracellular matrix Microorganisms in a biofilm can be 1,000 fold less susceptible to antibiotics than planktonic microorganisms
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Bacteria are protected in a biofilm
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Antibiotic Resistance
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Antibiotic Resistance in Biofilms
Tolerance in biofilms makes antibiotics less effective Up to 1,000 fold less susceptible to antibiotics Selection for bacteria that are more resistant to antibiotic Spread of antibiotic resistance Antibiotics kill bacteria except the resistant ones, which multiply, and in the end there are more resistant than non-resistant bacteria
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Multiresistant Bacteria
2 million healthcare-associated infections occur every year; 70% of the pathogens causing them are resistant to at least one antibiotic Numbers of healthcare-associated as well as community associated MRSA are increasing Horizontal gene transfer is promoted in biofilms; therefore, it is possible that antibiotic resistance spreads more easily than in planktonic populations Antibiotic resistant bacteria are common in VAP
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Antimicrobials Antibiotics => very specific, highly efficient, prone to development of resistance Antiseptics, antimicrobials (for example silver) => broad spectrum
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Biofilms on Foley catheters
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Biofilms on Foley catheters
Intraluminal contamination from the Collection bag Extraluminal contamination at the insertion site
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Biofilms and infection
The catheter is COLONIZED, the patient is INFECTED Bacteria can survive/multiply in biofilm. Biofilm provides reservoir for bacteria Microorganisms are detached from the biofilm and can infect a patient The presence of a biofilm strongly increases the likelihood that bacteria are available for infection
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Immune response to a biofilm
The bladder, ureter and urethra are lined with epithelial cells
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Immune response to a biofilm
Microorganisms colonize epithelium Microorganisms manage to get into tissue (either by damaging the tissue with toxin or by specific virulence mechanism) Microorganisms multiply in tissue, spread into lymphatic organs, and eventually in blood Immune system mobilizes cells to eliminate bacteria = Inflammation
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Incidence of CA-UTI Bacteriuria occurs in about 26% of patients
Symptomatic UTI: 16-32% of those who are bacteriuric Bacteremia related to CAUTI: 3.6% of those with bacteriuria, attributable mortality 12.7% (Saint, AJIC 2000;28:68-75.)
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Microbiology of CA-UTI
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Biofilms on Foley catheters
Prevention: trained personnel, aseptic technique handwashing Closed system proper securement Assess if Foley catheter is still necessary CDC recommendations:
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Biofilms on endotracheal tubes
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Biofilm on endotracheal tubes
In addition to microorganisms and microbial secretions there are also other components, such as mucus, blood cells, pollen particles etc...
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Biofilms on endotracheal tubes
Mucus is part of the host immune system, it traps particles such as bacteria, also prevents tissues from drying out. In the healthy body, mucus is swept away by cilia, and for the most part swallowed and digested. Removal of mucus by natural mechanisms does not occur in the intubated patient and it can accumulate above the cuff, or inside the ET tube Cough reflex does not work effectively in intubated patient, so if mucus particles with bacteria reach the lower respiratory tract, they can grow and spread and lead to infection
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Biofilms on endotracheal tubes
Pooled secretions above the cuff Oral Biofilm Intraluminal contamination from the ventilator or suction catheter
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Oral biofilm In a healthy adult, the oral cavity is colonized by more than 500 different kinds of bacteria (most of them are normal flora and do not cause harm). In the intubated patient, natural defense mechanisms, such as saliva production and swallowing are impaired Oral hygiene of intubated patients is difficult, because access is limited and it requires a substantial amount of nursing time If microorganisms are not sufficiently removed from the tooth surface, they colonize and form a biofilm (Plaque) If the plaque is not removed, the secretions in the biofilm (acids and sugars) can cause inflammation and damage to the teeth and gums (gingivitis)
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Biofilms on endotracheal tubes
ICU patients were swabbed to determine the colonization of the upper and lower Respiratory and GI regions Mouth/Oropharynx Upper GI tract Lower Respiratory Tract Inner lumen of ETT Gram negative bacteria Gram positive bacteria Feldman et al., 1999
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Biofilms on endotracheal tubes
Etiology shifts over intubation period: initially endogenous flora, later on exogenous, harder to treat microorganisms intubation > 80% of intubated patients are extubated by day 10 < 5 days ≥ 5 days Streptococcus pneumoniae Haemophilus influenzae AB sensitive Staphylococcus aureus MRSA Enterobacteriaceae (e.g. Klebsiella, E. coli) AGBN (Pseudomonas, Acinetobacter) Early onset Late onset
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When Biofilms spread into the lower respiratory tract, they can cause VAP
Microaspiration at the cuff Accumulation in the carina Aerosolization from the inside of the tube into the lung
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Biofilms on endotracheal tubes
Prevention - The IHI Ventilator Bundle Elevated bed position => avoids contamination by gastric reflux Daily sedation vacations and assessment of readiness to extubate peptic ulcer disease prophylaxis deep venous thrombosis prophylaxis Silver-coated endotracheal tube reduced the incidence of VAP in a Multicenter clinicial trial (Kollef et al. 2008: JAMA 300(7): ) VAP bundle:
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Summary Microorganisms form biofilms on surfaces such as medical devices Biofilms provide protection for microorganisms and make them more resistant to antibiotic treatment National organizations recommend bundle strategies to prevent device related infections
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