Session Type: 1-hour Oral Session
Session Title: 1-hour Oral Session
Authors(s): J. Howard-Anderson (1, 2), M. Davis (1, 2, 3), A. Page (1, 2, 3), C. Bower (2, 3, 4), G. Smith (2, 3, 4), J. Jacob (1, 2, 5), D. Weiss (1, 5), S. Satola (1, 2, 3, 5)
Authors Affiliations(s): (1) Emory University School of Medicine, Division of Infectious Diseases, United States, (2) Georgia Emerging Infections Program, United States, (3) Atlanta VA Medical Center, United States, (4) Foundation for Atlanta Veterans Education and Research, United States, (5) Emory Antibiotic Resistance Center, United States
Background:
Patients with carbapenem-resistant Pseudomonas aeruginosa (CRPA) have limited treatment options and may require treatment with colistin. Prevalence and impact of colistin heteroresistance (HR) in CRPA have been infrequently studied and multiple definitions of HR exist.
Methods:The Georgia Emerging Infections Program performed population and laboratory-based surveillance for CRPA (minimum inhibitory concentration [MIC] ≥8 µg/mL for doripenem, imipenem or meropenem) isolated from sterile sites, urine, respiratory tracts and wounds in Atlanta, GA, from 8/1/2016–7/31/2018. Isolates susceptible to colistin (MIC <4 µg/mL by broth microdilution) were assessed for colistin HR through population analysis profile (PAP). Standard PAP used a starting inoculum of ~1x109 cells (OD600=1.0) and 100 µL of culture spiral plated on increasing concentrations of colistin. A modified PAP (mPAP) used 10 µL drops of culture. Colonies were counted at 48 hours and two HR definitions were compared: HR1) growth at 4 and 8 µg/mL of colistin at a frequency of at least 0.0001% (1 in 106) of the main population on antibiotic-free media; HR2) growth at a colistin concentration ≥8x higher than the main population, at a frequency of at least 0.00001% (1 in 107). For non-cystic fibrosis patients hospitalized within 1 week of CRPA culture, we compared differences in clinical characteristics (obtained by chart review) and mortality based on colistin HR.
Results:Of 143 CRPA isolates, 17 (12%) met HR1 and an additional 47 met HR2 (64, 45%). Compared to standard PAP, mPAP had a specificity and sensitivity of 100% and 23.5%, respectively for HR1; 98.7% and 20.3%, respectively for HR2 (Figure 1). Characteristics of the 85 patients who were hospitalized within 1 week of CRPA culture are described in Tables 1-2. Patients with HR isolates were similar to those without HR, although patients with HR2 isolates had longer hospital stays (14 vs. 8 days, p=0.01). Neither HR definition was associated with 30- or 90-day mortality (p >0.05).
Conclusions:In Atlanta, GA, the prevalence of colistin HR in CRPA ranges from 12%–45% depending on the definition of HR used. mPAP may not be sufficient to screen for HR. In this small sample, colistin HR was not associated with increased mortality.
Keyword(s): Heteroresistance, carbapenem-resistant Pseudomonas aeruginosa, colistinCOI Other: J.H.A is supported by the Antibacterial Resistance Leadership Group fellowship [NIAID UM1AI104681]. The content is solely the responsibility of the authors and does not necessarily represent the official views of the NIH.
Session Type: 1-hour Oral Session
Session Title: 1-hour Oral Session
Authors(s): J. Howard-Anderson (1, 2), M. Davis (1, 2, 3), A. Page (1, 2, 3), C. Bower (2, 3, 4), G. Smith (2, 3, 4), J. Jacob (1, 2, 5), D. Weiss (1, 5), S. Satola (1, 2, 3, 5)
Authors Affiliations(s): (1) Emory University School of Medicine, Division of Infectious Diseases, United States, (2) Georgia Emerging Infections Program, United States, (3) Atlanta VA Medical Center, United States, (4) Foundation for Atlanta Veterans Education and Research, United States, (5) Emory Antibiotic Resistance Center, United States
Background:
Patients with carbapenem-resistant Pseudomonas aeruginosa (CRPA) have limited treatment options and may require treatment with colistin. Prevalence and impact of colistin heteroresistance (HR) in CRPA have been infrequently studied and multiple definitions of HR exist.
Methods:The Georgia Emerging Infections Program performed population and laboratory-based surveillance for CRPA (minimum inhibitory concentration [MIC] ≥8 µg/mL for doripenem, imipenem or meropenem) isolated from sterile sites, urine, respiratory tracts and wounds in Atlanta, GA, from 8/1/2016–7/31/2018. Isolates susceptible to colistin (MIC <4 µg/mL by broth microdilution) were assessed for colistin HR through population analysis profile (PAP). Standard PAP used a starting inoculum of ~1x109 cells (OD600=1.0) and 100 µL of culture spiral plated on increasing concentrations of colistin. A modified PAP (mPAP) used 10 µL drops of culture. Colonies were counted at 48 hours and two HR definitions were compared: HR1) growth at 4 and 8 µg/mL of colistin at a frequency of at least 0.0001% (1 in 106) of the main population on antibiotic-free media; HR2) growth at a colistin concentration ≥8x higher than the main population, at a frequency of at least 0.00001% (1 in 107). For non-cystic fibrosis patients hospitalized within 1 week of CRPA culture, we compared differences in clinical characteristics (obtained by chart review) and mortality based on colistin HR.
Results:Of 143 CRPA isolates, 17 (12%) met HR1 and an additional 47 met HR2 (64, 45%). Compared to standard PAP, mPAP had a specificity and sensitivity of 100% and 23.5%, respectively for HR1; 98.7% and 20.3%, respectively for HR2 (Figure 1). Characteristics of the 85 patients who were hospitalized within 1 week of CRPA culture are described in Tables 1-2. Patients with HR isolates were similar to those without HR, although patients with HR2 isolates had longer hospital stays (14 vs. 8 days, p=0.01). Neither HR definition was associated with 30- or 90-day mortality (p >0.05).
Conclusions:In Atlanta, GA, the prevalence of colistin HR in CRPA ranges from 12%–45% depending on the definition of HR used. mPAP may not be sufficient to screen for HR. In this small sample, colistin HR was not associated with increased mortality.
Keyword(s): Heteroresistance, carbapenem-resistant Pseudomonas aeruginosa, colistinCOI Other: J.H.A is supported by the Antibacterial Resistance Leadership Group fellowship [NIAID UM1AI104681]. The content is solely the responsibility of the authors and does not necessarily represent the official views of the NIH.
Session Type: 1-hour Oral Session
Session Title: 1-hour Oral Session
Authors(s): J. Howard-Anderson (1, 2), M. Davis (1, 2, 3), A. Page (1, 2, 3), C. Bower (2, 3, 4), G. Smith (2, 3, 4), J. Jacob (1, 2, 5), D. Weiss (1, 5), S. Satola (1, 2, 3, 5)
Authors Affiliations(s): (1) Emory University School of Medicine, Division of Infectious Diseases, United States, (2) Georgia Emerging Infections Program, United States, (3) Atlanta VA Medical Center, United States, (4) Foundation for Atlanta Veterans Education and Research, United States, (5) Emory Antibiotic Resistance Center, United States
Background:
Patients with carbapenem-resistant Pseudomonas aeruginosa (CRPA) have limited treatment options and may require treatment with colistin. Prevalence and impact of colistin heteroresistance (HR) in CRPA have been infrequently studied and multiple definitions of HR exist.
Methods:The Georgia Emerging Infections Program performed population and laboratory-based surveillance for CRPA (minimum inhibitory concentration [MIC] ≥8 µg/mL for doripenem, imipenem or meropenem) isolated from sterile sites, urine, respiratory tracts and wounds in Atlanta, GA, from 8/1/2016–7/31/2018. Isolates susceptible to colistin (MIC <4 µg/mL by broth microdilution) were assessed for colistin HR through population analysis profile (PAP). Standard PAP used a starting inoculum of ~1x109 cells (OD600=1.0) and 100 µL of culture spiral plated on increasing concentrations of colistin. A modified PAP (mPAP) used 10 µL drops of culture. Colonies were counted at 48 hours and two HR definitions were compared: HR1) growth at 4 and 8 µg/mL of colistin at a frequency of at least 0.0001% (1 in 106) of the main population on antibiotic-free media; HR2) growth at a colistin concentration ≥8x higher than the main population, at a frequency of at least 0.00001% (1 in 107). For non-cystic fibrosis patients hospitalized within 1 week of CRPA culture, we compared differences in clinical characteristics (obtained by chart review) and mortality based on colistin HR.
Results:Of 143 CRPA isolates, 17 (12%) met HR1 and an additional 47 met HR2 (64, 45%). Compared to standard PAP, mPAP had a specificity and sensitivity of 100% and 23.5%, respectively for HR1; 98.7% and 20.3%, respectively for HR2 (Figure 1). Characteristics of the 85 patients who were hospitalized within 1 week of CRPA culture are described in Tables 1-2. Patients with HR isolates were similar to those without HR, although patients with HR2 isolates had longer hospital stays (14 vs. 8 days, p=0.01). Neither HR definition was associated with 30- or 90-day mortality (p >0.05).
Conclusions:In Atlanta, GA, the prevalence of colistin HR in CRPA ranges from 12%–45% depending on the definition of HR used. mPAP may not be sufficient to screen for HR. In this small sample, colistin HR was not associated with increased mortality.
Keyword(s): Heteroresistance, carbapenem-resistant Pseudomonas aeruginosa, colistinCOI Other: J.H.A is supported by the Antibacterial Resistance Leadership Group fellowship [NIAID UM1AI104681]. The content is solely the responsibility of the authors and does not necessarily represent the official views of the NIH.
Session Type: 1-hour Oral Session
Session Title: 1-hour Oral Session
Authors(s): J. Howard-Anderson (1, 2), M. Davis (1, 2, 3), A. Page (1, 2, 3), C. Bower (2, 3, 4), G. Smith (2, 3, 4), J. Jacob (1, 2, 5), D. Weiss (1, 5), S. Satola (1, 2, 3, 5)
Authors Affiliations(s): (1) Emory University School of Medicine, Division of Infectious Diseases, United States, (2) Georgia Emerging Infections Program, United States, (3) Atlanta VA Medical Center, United States, (4) Foundation for Atlanta Veterans Education and Research, United States, (5) Emory Antibiotic Resistance Center, United States
Background:
Patients with carbapenem-resistant Pseudomonas aeruginosa (CRPA) have limited treatment options and may require treatment with colistin. Prevalence and impact of colistin heteroresistance (HR) in CRPA have been infrequently studied and multiple definitions of HR exist.
Methods:The Georgia Emerging Infections Program performed population and laboratory-based surveillance for CRPA (minimum inhibitory concentration [MIC] ≥8 µg/mL for doripenem, imipenem or meropenem) isolated from sterile sites, urine, respiratory tracts and wounds in Atlanta, GA, from 8/1/2016–7/31/2018. Isolates susceptible to colistin (MIC <4 µg/mL by broth microdilution) were assessed for colistin HR through population analysis profile (PAP). Standard PAP used a starting inoculum of ~1x109 cells (OD600=1.0) and 100 µL of culture spiral plated on increasing concentrations of colistin. A modified PAP (mPAP) used 10 µL drops of culture. Colonies were counted at 48 hours and two HR definitions were compared: HR1) growth at 4 and 8 µg/mL of colistin at a frequency of at least 0.0001% (1 in 106) of the main population on antibiotic-free media; HR2) growth at a colistin concentration ≥8x higher than the main population, at a frequency of at least 0.00001% (1 in 107). For non-cystic fibrosis patients hospitalized within 1 week of CRPA culture, we compared differences in clinical characteristics (obtained by chart review) and mortality based on colistin HR.
Results:Of 143 CRPA isolates, 17 (12%) met HR1 and an additional 47 met HR2 (64, 45%). Compared to standard PAP, mPAP had a specificity and sensitivity of 100% and 23.5%, respectively for HR1; 98.7% and 20.3%, respectively for HR2 (Figure 1). Characteristics of the 85 patients who were hospitalized within 1 week of CRPA culture are described in Tables 1-2. Patients with HR isolates were similar to those without HR, although patients with HR2 isolates had longer hospital stays (14 vs. 8 days, p=0.01). Neither HR definition was associated with 30- or 90-day mortality (p >0.05).
Conclusions:In Atlanta, GA, the prevalence of colistin HR in CRPA ranges from 12%–45% depending on the definition of HR used. mPAP may not be sufficient to screen for HR. In this small sample, colistin HR was not associated with increased mortality.
Keyword(s): Heteroresistance, carbapenem-resistant Pseudomonas aeruginosa, colistinCOI Other: J.H.A is supported by the Antibacterial Resistance Leadership Group fellowship [NIAID UM1AI104681]. The content is solely the responsibility of the authors and does not necessarily represent the official views of the NIH.