TY - JOUR
T1 - Evaluation of the performance of manual antimicrobial susceptibility testing methods and disk breakpoints for stenotrophomonas maltophilia
AU - Khan, Ayesha
AU - Pettaway, Cedric H.
AU - Bard, Jennifer Dien
AU - Arias, Cesar A.
AU - Bhatti, Micah M.
AU - Humphries, Romney M.
N1 - Copyright © 2021 American Society for Microbiology.
PY - 2021/5
Y1 - 2021/5
N2 -
Stenotrophomonas maltophilia are an emerging cause of serious infections with high associated mortality in immunocompromised patients. Treatment of
S. maltophilia infections is complicated by intrinsic resistance to many antimicrobials, including carbapenems, aminoglycosides, and some cephalosporins. Despite this, >90% of isolates are susceptible to trimethoprim-sulfamethoxazole (SXT), which is front-line therapy for this organism. Side-effects of SXT include bone marrow suppression, which precludes its use for many neutropenic patients. In this population, levofloxacin (LEV), minocycline (MIN), ceftazidime (CAZ), ciprofloxacin (CIP) and tigecycline (TIG) are used as alternative therapies - all of which require testing to inform susceptibilities. The reference standard method for testing
S. maltophilia is broth microdilution (BMD), but very few clinical laboratories perform reference BMD. Furthermore, interpretive criteria are not available for CIP or TIG for
S. maltophilia, although generic pharmacokinetic/pharmacodynamic (PK/PD) MIC breakpoints are available for these drugs. We assessed performance of disk and gradient diffusion tests relative to BMD for 109 contemporary isolates of
S. maltophilia Categorical agreement for SXT, LEV and MIN disk diffusion was 93%, 89%, and 95%, respectively. Categorical agreement for SXT, LEV, MIN and CAZ gradient strips was 98%, 85%, 93%, 71%, respectively by Etest (bioMerieux), and 98%, 83%, 99%, and 73%, by MTS (Liofilchem). CIP and TGC, two clinically valuable alternatives to SXT, did not demonstrate promising disk to MIC correlates using CLSI M100
P. aeruginosa or PK/PD breakpoints. Manual commercial tests perform well for
S. maltophilia, with the exception of tests for LEV and CAZ, where high error rates were observed.
AB -
Stenotrophomonas maltophilia are an emerging cause of serious infections with high associated mortality in immunocompromised patients. Treatment of
S. maltophilia infections is complicated by intrinsic resistance to many antimicrobials, including carbapenems, aminoglycosides, and some cephalosporins. Despite this, >90% of isolates are susceptible to trimethoprim-sulfamethoxazole (SXT), which is front-line therapy for this organism. Side-effects of SXT include bone marrow suppression, which precludes its use for many neutropenic patients. In this population, levofloxacin (LEV), minocycline (MIN), ceftazidime (CAZ), ciprofloxacin (CIP) and tigecycline (TIG) are used as alternative therapies - all of which require testing to inform susceptibilities. The reference standard method for testing
S. maltophilia is broth microdilution (BMD), but very few clinical laboratories perform reference BMD. Furthermore, interpretive criteria are not available for CIP or TIG for
S. maltophilia, although generic pharmacokinetic/pharmacodynamic (PK/PD) MIC breakpoints are available for these drugs. We assessed performance of disk and gradient diffusion tests relative to BMD for 109 contemporary isolates of
S. maltophilia Categorical agreement for SXT, LEV and MIN disk diffusion was 93%, 89%, and 95%, respectively. Categorical agreement for SXT, LEV, MIN and CAZ gradient strips was 98%, 85%, 93%, 71%, respectively by Etest (bioMerieux), and 98%, 83%, 99%, and 73%, by MTS (Liofilchem). CIP and TGC, two clinically valuable alternatives to SXT, did not demonstrate promising disk to MIC correlates using CLSI M100
P. aeruginosa or PK/PD breakpoints. Manual commercial tests perform well for
S. maltophilia, with the exception of tests for LEV and CAZ, where high error rates were observed.
KW - Antibiotic resistance
KW - Antimicrobial agents
KW - Blood culture
KW - Bloodstream infections
KW - Diagnostics
KW - Gram-negative bacteria
KW - Immunocompromised hosts
KW - Opportunistic infections
KW - Stenotrophomonas
KW - Susceptibility testing
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U2 - 10.1128/AAC.02631-20
DO - 10.1128/AAC.02631-20
M3 - Article
C2 - 33558287
AN - SCOPUS:85105066159
SN - 0066-4804
VL - 65
JO - Antimicrobial Agents and Chemotherapy
JF - Antimicrobial Agents and Chemotherapy
IS - 5
M1 - e02631-20
ER -