Session Type: ePosters
Session Title: ePosters
Authors(s): M. Loiodice, L. Peixe, Â. Novais
Authors Affiliations(s): UCIBIO, Faculty of Pharmacy, Portugal
Background:
High-risk Klebsiella pneumoniae (Kp) subpopulations causing hard-to-treat, hospital-acquired infections persist for long periods in the nosocomial environment. As ultraviolet C (UVC) light is frequently used for disinfection, due to its mutagenic and bactericidal effects, we evaluated the UVC tolerance of representative Kp strains.
Methods:We compared the effects of UVC light (wavelenght λ = 254 nm; irradiance I1m = 21 µW cm-2) on: i) twenty-two Kp strains of high-risk, multi-drug resistant (MDR) clones (e.g. CG258, ST147, ST307) with specific capsular types (e.g. K24, K64, KL102, KL107), and hyper-virulent Kp (hvKp, K1 type) strains, identified from human infections; ii) seven Kp susceptible strains, colonizing humans, animals or from environment (2003-2018). Two Escherichia coli (ATCC 25922 and E. coli ST131) were also tested. Bacterial suspensions adjusted to 0.5 McFarland were exposed to UVC light at 15 cm of distance for 10 seconds, and serial dilutions were plated on PCA (plate count agar) plates in triplicates. Colony-forming units (CFUs) were counted and compared to controls, non-exposed to UVs.
Results:In our experimental conditions, UVC light totally eradicated (100% mortality) E. coli strains, including one ST131 MDR isolate. Furthermore, we observed an eradication of >99% of most (n=19/22; 86%) high-risk MDR Kp and hvKp strains, regardless the clone, K-type composition or hypermucoviscous phenotype expression (observed in 3 isolates), as well as in most (n=6/7; 86%) of non-high-risk strains. Moreover, lower eradication percentages were observed for one ST45-K24 (97%), one human colonizer (94%), and one carbapenemase-producing ST22-K9 clone (exhibiting the lowest eradication score of 79%).
Conclusions:This is the first study providing data on susceptibility to UVC light of diverse Kp lineages, and our data highlights the survival ability of some strains, including highly persistent and widespread carbapenemase-producing clones. However, additional studies are needed to evaluate frequency and type of high-tolerant strains, and possible differences on recovery rates between clones. Our data further suggests that E. coli, including ST131 strain, has a much higher susceptibility than Kp to UVC light. Differences in the activity of DNA repair mechanisms counteracting UVC damage might justify the variable susceptibility to an established and broadly used disinfection process.
Keyword(s): Klebsiella pneumoniae, high-risk clones, UVC disinfectionSession Type: ePosters
Session Title: ePosters
Authors(s): M. Loiodice, L. Peixe, Â. Novais
Authors Affiliations(s): UCIBIO, Faculty of Pharmacy, Portugal
Background:
High-risk Klebsiella pneumoniae (Kp) subpopulations causing hard-to-treat, hospital-acquired infections persist for long periods in the nosocomial environment. As ultraviolet C (UVC) light is frequently used for disinfection, due to its mutagenic and bactericidal effects, we evaluated the UVC tolerance of representative Kp strains.
Methods:We compared the effects of UVC light (wavelenght λ = 254 nm; irradiance I1m = 21 µW cm-2) on: i) twenty-two Kp strains of high-risk, multi-drug resistant (MDR) clones (e.g. CG258, ST147, ST307) with specific capsular types (e.g. K24, K64, KL102, KL107), and hyper-virulent Kp (hvKp, K1 type) strains, identified from human infections; ii) seven Kp susceptible strains, colonizing humans, animals or from environment (2003-2018). Two Escherichia coli (ATCC 25922 and E. coli ST131) were also tested. Bacterial suspensions adjusted to 0.5 McFarland were exposed to UVC light at 15 cm of distance for 10 seconds, and serial dilutions were plated on PCA (plate count agar) plates in triplicates. Colony-forming units (CFUs) were counted and compared to controls, non-exposed to UVs.
Results:In our experimental conditions, UVC light totally eradicated (100% mortality) E. coli strains, including one ST131 MDR isolate. Furthermore, we observed an eradication of >99% of most (n=19/22; 86%) high-risk MDR Kp and hvKp strains, regardless the clone, K-type composition or hypermucoviscous phenotype expression (observed in 3 isolates), as well as in most (n=6/7; 86%) of non-high-risk strains. Moreover, lower eradication percentages were observed for one ST45-K24 (97%), one human colonizer (94%), and one carbapenemase-producing ST22-K9 clone (exhibiting the lowest eradication score of 79%).
Conclusions:This is the first study providing data on susceptibility to UVC light of diverse Kp lineages, and our data highlights the survival ability of some strains, including highly persistent and widespread carbapenemase-producing clones. However, additional studies are needed to evaluate frequency and type of high-tolerant strains, and possible differences on recovery rates between clones. Our data further suggests that E. coli, including ST131 strain, has a much higher susceptibility than Kp to UVC light. Differences in the activity of DNA repair mechanisms counteracting UVC damage might justify the variable susceptibility to an established and broadly used disinfection process.
Keyword(s): Klebsiella pneumoniae, high-risk clones, UVC disinfection
Session Type: ePosters
Session Title: ePosters
Authors(s): M. Loiodice, L. Peixe, Â. Novais
Authors Affiliations(s): UCIBIO, Faculty of Pharmacy, Portugal
Background:
High-risk Klebsiella pneumoniae (Kp) subpopulations causing hard-to-treat, hospital-acquired infections persist for long periods in the nosocomial environment. As ultraviolet C (UVC) light is frequently used for disinfection, due to its mutagenic and bactericidal effects, we evaluated the UVC tolerance of representative Kp strains.
Methods:We compared the effects of UVC light (wavelenght λ = 254 nm; irradiance I1m = 21 µW cm-2) on: i) twenty-two Kp strains of high-risk, multi-drug resistant (MDR) clones (e.g. CG258, ST147, ST307) with specific capsular types (e.g. K24, K64, KL102, KL107), and hyper-virulent Kp (hvKp, K1 type) strains, identified from human infections; ii) seven Kp susceptible strains, colonizing humans, animals or from environment (2003-2018). Two Escherichia coli (ATCC 25922 and E. coli ST131) were also tested. Bacterial suspensions adjusted to 0.5 McFarland were exposed to UVC light at 15 cm of distance for 10 seconds, and serial dilutions were plated on PCA (plate count agar) plates in triplicates. Colony-forming units (CFUs) were counted and compared to controls, non-exposed to UVs.
Results:In our experimental conditions, UVC light totally eradicated (100% mortality) E. coli strains, including one ST131 MDR isolate. Furthermore, we observed an eradication of >99% of most (n=19/22; 86%) high-risk MDR Kp and hvKp strains, regardless the clone, K-type composition or hypermucoviscous phenotype expression (observed in 3 isolates), as well as in most (n=6/7; 86%) of non-high-risk strains. Moreover, lower eradication percentages were observed for one ST45-K24 (97%), one human colonizer (94%), and one carbapenemase-producing ST22-K9 clone (exhibiting the lowest eradication score of 79%).
Conclusions:This is the first study providing data on susceptibility to UVC light of diverse Kp lineages, and our data highlights the survival ability of some strains, including highly persistent and widespread carbapenemase-producing clones. However, additional studies are needed to evaluate frequency and type of high-tolerant strains, and possible differences on recovery rates between clones. Our data further suggests that E. coli, including ST131 strain, has a much higher susceptibility than Kp to UVC light. Differences in the activity of DNA repair mechanisms counteracting UVC damage might justify the variable susceptibility to an established and broadly used disinfection process.
Keyword(s): Klebsiella pneumoniae, high-risk clones, UVC disinfectionSession Type: ePosters
Session Title: ePosters
Authors(s): M. Loiodice, L. Peixe, Â. Novais
Authors Affiliations(s): UCIBIO, Faculty of Pharmacy, Portugal
Background:
High-risk Klebsiella pneumoniae (Kp) subpopulations causing hard-to-treat, hospital-acquired infections persist for long periods in the nosocomial environment. As ultraviolet C (UVC) light is frequently used for disinfection, due to its mutagenic and bactericidal effects, we evaluated the UVC tolerance of representative Kp strains.
Methods:We compared the effects of UVC light (wavelenght λ = 254 nm; irradiance I1m = 21 µW cm-2) on: i) twenty-two Kp strains of high-risk, multi-drug resistant (MDR) clones (e.g. CG258, ST147, ST307) with specific capsular types (e.g. K24, K64, KL102, KL107), and hyper-virulent Kp (hvKp, K1 type) strains, identified from human infections; ii) seven Kp susceptible strains, colonizing humans, animals or from environment (2003-2018). Two Escherichia coli (ATCC 25922 and E. coli ST131) were also tested. Bacterial suspensions adjusted to 0.5 McFarland were exposed to UVC light at 15 cm of distance for 10 seconds, and serial dilutions were plated on PCA (plate count agar) plates in triplicates. Colony-forming units (CFUs) were counted and compared to controls, non-exposed to UVs.
Results:In our experimental conditions, UVC light totally eradicated (100% mortality) E. coli strains, including one ST131 MDR isolate. Furthermore, we observed an eradication of >99% of most (n=19/22; 86%) high-risk MDR Kp and hvKp strains, regardless the clone, K-type composition or hypermucoviscous phenotype expression (observed in 3 isolates), as well as in most (n=6/7; 86%) of non-high-risk strains. Moreover, lower eradication percentages were observed for one ST45-K24 (97%), one human colonizer (94%), and one carbapenemase-producing ST22-K9 clone (exhibiting the lowest eradication score of 79%).
Conclusions:This is the first study providing data on susceptibility to UVC light of diverse Kp lineages, and our data highlights the survival ability of some strains, including highly persistent and widespread carbapenemase-producing clones. However, additional studies are needed to evaluate frequency and type of high-tolerant strains, and possible differences on recovery rates between clones. Our data further suggests that E. coli, including ST131 strain, has a much higher susceptibility than Kp to UVC light. Differences in the activity of DNA repair mechanisms counteracting UVC damage might justify the variable susceptibility to an established and broadly used disinfection process.
Keyword(s): Klebsiella pneumoniae, high-risk clones, UVC disinfection