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Virucidal Performance of Antimicrobials against Norovirus in Shorter Contact Time
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Vol. 36 No. 5
2:00 – 2:15 PM Publication Number 202
Investigation of a Cluster of Genomically Identical Pseudomonas aeruginosa Blood Isolates Following Endoscopic Retrograde Cholangiopancreatography in a Gastroenterology Laboratory Sandra Reiner, RN, BSN, Infection Control and Prevention Coordinator, Northwestern Memorial Hospital, Chicago, IL. Issue: Three patients developed P. aeruginosa bacteremia following endoscopic retrograde cholangiopancreatography (ERCP) performed in the same Gastroenterology Lab (GI Lab) over a five week period of time. Project: An outbreak investigation was performed including additional case-finding, common source identification through device and other environmental cultures and isolate strain typing with pulsed-field gel electrophoresis (PFGE). Post-cleaning and post-high level disinfection samples were collected from all twelve ERCP scopes by flushing sterile water through the air/water, biopsy, suction and elevator channels. Direct swabs of the elevator channel tips were also collected with the elevator in the elevated and closed positions. Careful scrutiny of each step of the existing device processing procedure was undertaken. Results: Retrospective review of all P. aeruginosa blood isolates among patients who had undergone ERCP during the four months preceding the cluster revealed one additional possible case. The fourth patient’s isolate was not available for typing. All three affected patients whose isolates were available for typing had procedures performed with the same device, and PFGE revealed that they were genomically identical. Eleven post-cleaning and post-high level disinfection cultures from six of twelve scopes, including the implicated scope, yielded P. aeruginosa. Positive cultures were obtained from six elevator channels (45%), three biopsy channels (27%), two air/water channels (18%) and one suction channel (9%). Fluid samples from two of ten bottles of enzymatic solution that were used for initial post-procedure rinsing in each procedure room, topped off each day from a larger common-source bottle that was mixed and kept in the scope reprocessing room, were also positive for P. aeruginosa. Samples from the larger bottle of enzymatic solution were also positive for S. maltophila. Wipe/bulk cultures and fluid cultures from the automated washers were all negative for growth. PFGE of all device and fluid isolates demonstrated clonality to the patient strain. It was discovered that enzymatic solution concentration for cleaning post-procedure scopes before placing them in automatic washers was estimated, not measured. The outbreak was terminated by, 1) eliminating refillable enzymatic bottles in procedure rooms, 2) replacing refillable bottles with single case enzymatic solution packets, 3) standardizing the concentration of enzymatic solution used for cleaning scopes, and 4) repeating standard competencies for dedicated reprocessing personnel. Continuous prospective surveillance has not revealed any more cases. Lessons Learned: Outbreaks in the GI Lab can be controlled by using recommended chemical concentrations, eliminating common source enzymatic solution bottles, prohibiting topping off and strict attention to the details of scope cleaning, especially elevator channels. Implementation of weekly prospective surveillance allows for early case identification, investigation and intervention.
2:15 – 2:30 PM Publication Number 203
Virucidal Performance of Antimicrobials against Norovirus in Shorter Contact Time Kelly M. Whitehead, BS, Research Scientist Microbiology; Reckitt Benckiser Inc., Center of Innovation, Montvale, NJ; Karen A. McCue, MS, Research Fellow; Reckitt Benckiser, Inc., Center of Innovation, Montvale, NJ Background: An increase in Acute Gastroenteritis Infections (AGE) caused by Norovirus was observed in 2006 when compared with 2005. Norovirus is highly contagious and people in communal settings and in particular
June 2008
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the immunocompromised are at increased risk. One potential route of transmission is through contact with contaminated environmental surfaces. Targeted disinfection is important in preventing and controlling outbreaks. Norovirus is a non enveloped virus and not inactivated by all disinfectants, especially at short contact times. Objectives: The purpose of this study was to evaluate a spectrum of known disinfectant antimicrobials at different concentrations, both alone and in formulation to assess efficacy against Norovirus at shorter contact times. Methods: Feline Calicivirus (FCV), a surrogate for Norovirus, was obtained from reference collection of the American Type Culture Collection (ATCC VR -782) and propagated in Crandel Reese feline kidney cells (CRFK, ATCC CCL-94). Evaluation of the test treatments were conducted in accordance with ASTM E 1053-97 method and US EPA Pesticide Efficacy Data Requirements: Virucides, DIS/TSS-7. Briefly, FCV suspension was dried on a non porous surface; the test product was then added over the dried film and remained for the specified contact time. After exposure and neutralization, the virus-antimicrobial mixture was assayed in the CRFK host system. The virus titer of an untreated surface is determined by the median infective dose (ID 50) method of virus titration. The virusantimicrobial mixture is assayed in the CRFK host system; dilutions beyond the cytotoxicity range of the antimicrobial are considered in calculating reductions. The extent of virus inactivation by the antimicrobial is determined. Results are recorded as log 10- virus inactivated. Results: Antimicrobial actives sodium hypochlorite, acid, quaternary and alcohol were evaluated alone and in formulation for efficacy against norovirus in short contact times. Sodium hypochlorite at a concentration of 1000 ppm available chlorine, pH 10.6, demonstrated .3 log10 reduction and complete inactivation of FCV in a one minute contact time. Likewise, both organic and inorganic acids at pH 2 showed a .3 log 10 reduction and complete inactivation of the challenge virus in a one minute contact time. Alternatively, alcohol and quaternary as actives alone were not as effective. Both ethanol and isopropyl alcohol at 60% concentration, and alkyl dimethyl benzyl ammonium chloride at 0.3% (3000ppm) active, provided only a one log 10 reduction against FCV. However, when these actives were appropriately formulated as disinfectants with other ingredients including pH adjusters, complete inactivation of FCV was achieved in a shorter contact time. As a result, a disinfectant formulation containing 60 % ethanol, 0.1% quaternary and a pH of 10.8 demonstrated a .4 log 10 reduction and complete inactivation of FCV in a one minute contact time. These results show a broad spectrum of actives effective against norviruses and the important role formulation science play in developing such disinfectants effective against hard to inactivate viruses like norovirus in shorter contact times. Conclusions: A broad spectrum of antimicrobial actives, when properly formulated, can achieve disinfectant efficacy against norovirus in a shorter contact time of one minute. This data should be helpful to the infection control community in the selection of appropriate products in the prevention and control of this major nosocomial and community pathogen.
Oral Abstracts Session 4 Device Related/Site Specific Tuesday June 17, 2008 Convention Center – Room XXX 1:30 – 1:45 PM Publication Number 204
Interventions Resulting in a Sustained Decrease in Ventriculitis Rates in a Neurology/Neurosurgical Intensive Care Unit.
Vol. 36 No. 5
2:00 – 2:15 PM Publication Number 202
Investigation of a Cluster of Genomically Identical Pseudomonas aeruginosa Blood Isolates Following Endoscopic Retrograde Cholangiopancreatography in a Gastroenterology Laboratory Sandra Reiner, RN, BSN, Infection Control and Prevention Coordinator, Northwestern Memorial Hospital, Chicago, IL. Issue: Three patients developed P. aeruginosa bacteremia following endoscopic retrograde cholangiopancreatography (ERCP) performed in the same Gastroenterology Lab (GI Lab) over a five week period of time. Project: An outbreak investigation was performed including additional case-finding, common source identification through device and other environmental cultures and isolate strain typing with pulsed-field gel electrophoresis (PFGE). Post-cleaning and post-high level disinfection samples were collected from all twelve ERCP scopes by flushing sterile water through the air/water, biopsy, suction and elevator channels. Direct swabs of the elevator channel tips were also collected with the elevator in the elevated and closed positions. Careful scrutiny of each step of the existing device processing procedure was undertaken. Results: Retrospective review of all P. aeruginosa blood isolates among patients who had undergone ERCP during the four months preceding the cluster revealed one additional possible case. The fourth patient’s isolate was not available for typing. All three affected patients whose isolates were available for typing had procedures performed with the same device, and PFGE revealed that they were genomically identical. Eleven post-cleaning and post-high level disinfection cultures from six of twelve scopes, including the implicated scope, yielded P. aeruginosa. Positive cultures were obtained from six elevator channels (45%), three biopsy channels (27%), two air/water channels (18%) and one suction channel (9%). Fluid samples from two of ten bottles of enzymatic solution that were used for initial post-procedure rinsing in each procedure room, topped off each day from a larger common-source bottle that was mixed and kept in the scope reprocessing room, were also positive for P. aeruginosa. Samples from the larger bottle of enzymatic solution were also positive for S. maltophila. Wipe/bulk cultures and fluid cultures from the automated washers were all negative for growth. PFGE of all device and fluid isolates demonstrated clonality to the patient strain. It was discovered that enzymatic solution concentration for cleaning post-procedure scopes before placing them in automatic washers was estimated, not measured. The outbreak was terminated by, 1) eliminating refillable enzymatic bottles in procedure rooms, 2) replacing refillable bottles with single case enzymatic solution packets, 3) standardizing the concentration of enzymatic solution used for cleaning scopes, and 4) repeating standard competencies for dedicated reprocessing personnel. Continuous prospective surveillance has not revealed any more cases. Lessons Learned: Outbreaks in the GI Lab can be controlled by using recommended chemical concentrations, eliminating common source enzymatic solution bottles, prohibiting topping off and strict attention to the details of scope cleaning, especially elevator channels. Implementation of weekly prospective surveillance allows for early case identification, investigation and intervention.
2:15 – 2:30 PM Publication Number 203
Virucidal Performance of Antimicrobials against Norovirus in Shorter Contact Time Kelly M. Whitehead, BS, Research Scientist Microbiology; Reckitt Benckiser Inc., Center of Innovation, Montvale, NJ; Karen A. McCue, MS, Research Fellow; Reckitt Benckiser, Inc., Center of Innovation, Montvale, NJ Background: An increase in Acute Gastroenteritis Infections (AGE) caused by Norovirus was observed in 2006 when compared with 2005. Norovirus is highly contagious and people in communal settings and in particular
June 2008
E199
the immunocompromised are at increased risk. One potential route of transmission is through contact with contaminated environmental surfaces. Targeted disinfection is important in preventing and controlling outbreaks. Norovirus is a non enveloped virus and not inactivated by all disinfectants, especially at short contact times. Objectives: The purpose of this study was to evaluate a spectrum of known disinfectant antimicrobials at different concentrations, both alone and in formulation to assess efficacy against Norovirus at shorter contact times. Methods: Feline Calicivirus (FCV), a surrogate for Norovirus, was obtained from reference collection of the American Type Culture Collection (ATCC VR -782) and propagated in Crandel Reese feline kidney cells (CRFK, ATCC CCL-94). Evaluation of the test treatments were conducted in accordance with ASTM E 1053-97 method and US EPA Pesticide Efficacy Data Requirements: Virucides, DIS/TSS-7. Briefly, FCV suspension was dried on a non porous surface; the test product was then added over the dried film and remained for the specified contact time. After exposure and neutralization, the virus-antimicrobial mixture was assayed in the CRFK host system. The virus titer of an untreated surface is determined by the median infective dose (ID 50) method of virus titration. The virusantimicrobial mixture is assayed in the CRFK host system; dilutions beyond the cytotoxicity range of the antimicrobial are considered in calculating reductions. The extent of virus inactivation by the antimicrobial is determined. Results are recorded as log 10- virus inactivated. Results: Antimicrobial actives sodium hypochlorite, acid, quaternary and alcohol were evaluated alone and in formulation for efficacy against norovirus in short contact times. Sodium hypochlorite at a concentration of 1000 ppm available chlorine, pH 10.6, demonstrated .3 log10 reduction and complete inactivation of FCV in a one minute contact time. Likewise, both organic and inorganic acids at pH 2 showed a .3 log 10 reduction and complete inactivation of the challenge virus in a one minute contact time. Alternatively, alcohol and quaternary as actives alone were not as effective. Both ethanol and isopropyl alcohol at 60% concentration, and alkyl dimethyl benzyl ammonium chloride at 0.3% (3000ppm) active, provided only a one log 10 reduction against FCV. However, when these actives were appropriately formulated as disinfectants with other ingredients including pH adjusters, complete inactivation of FCV was achieved in a shorter contact time. As a result, a disinfectant formulation containing 60 % ethanol, 0.1% quaternary and a pH of 10.8 demonstrated a .4 log 10 reduction and complete inactivation of FCV in a one minute contact time. These results show a broad spectrum of actives effective against norviruses and the important role formulation science play in developing such disinfectants effective against hard to inactivate viruses like norovirus in shorter contact times. Conclusions: A broad spectrum of antimicrobial actives, when properly formulated, can achieve disinfectant efficacy against norovirus in a shorter contact time of one minute. This data should be helpful to the infection control community in the selection of appropriate products in the prevention and control of this major nosocomial and community pathogen.
Oral Abstracts Session 4 Device Related/Site Specific Tuesday June 17, 2008 Convention Center – Room XXX 1:30 – 1:45 PM Publication Number 204
Interventions Resulting in a Sustained Decrease in Ventriculitis Rates in a Neurology/Neurosurgical Intensive Care Unit.