Growth Inhibition of Microorganisms Involved in Catheter- Related Infections by an Antimicrobial Transparent Iv Dressing Contaning Chlorhexidine Gluconate (chg)

updated) Introduction: Infections associated with intravascular devices represent 10 to 20% of all nosocomial infections and are mostly caused by microorganisms belonging to the skin flora. Antiseptic agents are used to disinfect the skin prior to catheter insertion, to reduce the risk of device colonization by the skin microorganisms. Nevertheless, the skin flora will rebound over time and will be able to colonize from 2 to 71% of all the inserted vascular devices (1). Transparent IV dressings allowing continuous observation of the insertion sites and early recognition of signs of infections, and antimicrobial dressings, suppressing skin flora re-growth, are valuable elements for best practices in IV management. This study is part of the efficacy evaluation performed with a novel dressing, the 3MTM TegadermTM CHG Chlorhexidine Gluconate IV Securement Dressing, which combines both transparency and antimicrobial activity. Objective: Demonstrate antimicrobial activity of TegadermTM CHG gel pad against microorganisms commonly associated with CR-infections by an in vitro assessment of growth inhibition. Methods: 1. Zone of Inhibition: Suspensions of microorganisms (approximately 108 cfu / mL) were prepared in sterile Butterfield’s phosphate buffered water from overnight growth plates. Mueller-Hinton (MH) agar plates were inoculated with the test microorganisms. Die-cut 24 mm disks from TegadermTM CHG dressings were placed onto the agar surface. Duplicate samples were prepared for each microorganism and incubated overnight incubation at 35 ± 2°C. The diameter of the zone of inhibition was measured. 2. Aged Zone of Inhibition: The experiment described above was performed with TegadermTM CHG dressings that were subject to standard ICH aging conditions (25oC/60% humidity & 30oC/65% humidity) for 22 months. TegadermTM CHG dressings that were not aged served as the control to determine the ability of the aged TegadermTM CHG to retain its antimicrobial properties. Results: Antimicrobial activity of the TegadermTM CHG gel pad was tested against a panel of 37 microorganisms, comprised of 21 gram positive and 14 gram negative bacteria, and 2 yeasts. TegadermTM CHG susceptibility was observed for all the microorganisms tested among those multiple strains of coagulase-negative staphylococci and Staphylococcus aureus – including those methicillin-resistant strains – and vancomycinresistant enterococci (Table 1, 2 and 3; figures 5, 6 and 7). Aged TegadermTM CHG, also generated clear zones of growth inhibition for the microorganisms tested. Conclusions: The TegadermTM CHG dressing demonstrated broad-spectrum antimicrobial activity against all 37 strains of microorganisms tested. TegadermTM CHG retains its antimicrobial properties as demonstrated by the aged dressings ability to produce similar zones of inhibition compared to unaged dressings. MATERIAL AND METHODS TegadermTM CHG integrates an adhesive, antimicrobial CHG-impregnated gel pad onto a moisture vapor permeable transparent dressing. This feature allows a single-step yet easy application directly over the insertion site following catheter insertion or during follow-up site care. The gel rapidly softens on skin and molds around the catheter, ensuring intimate contact of the CHG-impregnated surface along the entire insertion site (Figure 3). The integrated gel pad by adhering and enveloping the catheter, potentially minimizes pistoning movement of the catheter into the skin. Pistoning movement of the catheter can facilitate entry of microorganisms into the insertion tract (14). The gel also absorbs up to eight times its weight in fluid, preventing accumulation of moisture on the site. Features of the CHG-Impregnated Dressing Zones of Inhibition around the TegadermTM CHG gel pad • Suspensions of microorganisms (approximately 108 cfu / mL) were prepared in sterile Butterfield’s phosphate buffered water from overnight growth plates. • Mueller-Hinton (MH) agar plates were uniformly inoculated with the test microorganisms (tables1, 2 and 3). • Die-cut 24 mm gel disks from TegadermTM CHG dressings were placed onto the agar surface. • Duplicate samples were prepared for each microorganism. • After overnight incubation at 35 ± 2°C, the diameter of the zone of inhibition (w) was measured (figure 4). Zone of Inhibition around aged TegadermTM CHG gel pad • The experiment described above was performed with TegadermTM CHG dressings that were subject to standard ICH aging conditions (25oC/60% humidity & 30oC/65% humidity) for 22 months. • TegadermTM CHG dressings that were not aged served as the control to determine the ability of the aged TegadermTM CHG to retain its antimicrobial properties. Figure 3. The TegadermTM CHG antimicrobial i.v. securement dressing DISCUSSION AND CONCLUSIONS • The TegadermTM CHG gel pad produced a circular zone of inhibition in which the amount of antimicrobial exceeded inhibitory concentrations for each of the microorganisms tested. • The broad spectrum activity of the TegadermTM CHG gel pad was demonstrated by the ability to produce this effect against gram positive, gram negative, and yeast microorganisms. • TegadermTM CHG retains its antimicrobial properties as demonstrated by the aged dressings ability to produce similar zones of inhibition compared to unaged dressings. • Antimicrobial activity was observed against all major genre of microorganisms that cause CR-BSI or commonly colonize catheter tips (Figure 2) including: methicillin-resistant staphylococci (MRSA and MRSE), coagulase-negative staphylococci (CNS), vancomycin-resistant enterococci (VRE), and Staphylococcus aureus • The antimicrobial efficacy of TegadermTM CHG documented in the present study complements the results of in vitro time-kill assays and studies onhealthy volunteers demonstrating skin flora killing and suppression of regrowth after prepping (10, 13).w Figure 4.Measurement of the diameterof the zone of inhibitionREFERENCESRESULTS 57.7413812Corynebacterium diphtheriae32.60Enterococcus faecalis Wound Isolate #2338.8719433Enterococcus faecalis39.257080Enterococcus faecalis39.8051559Enterococcus faecium (MDR)38.20700221Enterococcus faecium (VRE)35.40Staphylococcus aureus Nasal Isolate #84942.64Staphylococcus aureus (MRSA) USA 80042.83Staphylococcus aureus (MRSA) USA 50044.72Staphylococcus aureus (MRSA) USA 60042.08Staphylococcus aureus (MRSA) USA 30041.70Staphylococcus aureus (MRSA) USA 10044.1533592Staphylococcus aureus (MRSA/GRSA)41.7025923Staphylococcus aureus41.2Staphylococcus epidermidis (MRSE) nasal isolate #49241.4551625Staphylococcus epidermidis (MRSE)47.5514990Staphylococcus epidermidis48.8749134Staphylococcus epidermidis45.2849461Staphylococcus epidermidis40.3813518Staphylococcus epidermidis46.0412228Staphylococcus epidermidisAverage Zonediameter (mm)ATCCGram PositiveTable 1. Gram Positive microorganisms strains tested with corresponding averagezone of inhibition (mm) 33.8058716Candida albicans38.6010231Candida albicansAverage Zonediameter (mm)ATCCYeast33.027002Proteus mirabilis35.6612453Proteus mirabilis38.4925922Escherichia coli31.2023357Klebsiella pneumoniae32.8013883Klebsiella pneumoniae32.6035549Enterobacter cloacae33.0027853Pseudomonas aeruginosa35.289027Pseudomonas aeruginosa36.7935032Pseudomonas aeruginosa36.7910662Pseudomonas aeruginosa36.4210145Pseudomonas aeruginosa33.20Acinetobacter baumannii Wound Isolate #12-435.85BAA-747Acinetobacter baumannii36.7919606Acinetobacter baumanniiAverage Zonediameter (mm)ATCCGram NegativeTable 2. Gram Negative bacteria and Yeast strains tested with correspondingaverage zone of inhibition (mm) 39.8338.6938.3110231Candida albicans35.51535.51535.3214756Serratia marcescens37.9538.8839.2633592Staphylococcus aureus(MRSA/GRSA)UnagedControlAged 22months @30oC/65%humidityAged 22months @25oC/60%humidityATCCMicroorganismAverage Zone diameter (mm)• The TegadermTM CHG gel pad was tested for antimicrobial activity against 37 microorganisms, including 21 gram positive and 14 gram negativebacteria, and 2 yeasts.• TegadermTM CHG, that was subject to standard ICH aging conditions for 22 months, was tested for antimicrobial activity against a gram positive, gramnegative, and a yeast microorganism.• TegadermTM CHG, aged and new, generated clear zones of growth inhibition for all the microorganisms tested.• Table 1, 2, and 3 lists all of the microorganisms tested and their corresponding zone of inhibition diameters.• The spider web figures 5, 6, and 7 represent the zone of inhibition diameter produced by the TegadermTM CHG gel pad for each microorganism tested. Table 3. Strains of microorganisms tested with aged TegadermTM CHG Dressingwith corresponding average zone of inhibitionFigure 5. Graphical representation of the zones of inhibition for Gram Positive bacteria Figure 6. Graphical representation of the zones of inhibition for Gram Negative bacteriaand Yeast Figure 7. Graphical representation of the zones of inhibition with aged TegadermTM CHGDressing