Table 2. Open in new tab Gaps in US Food...

Threat Level	Antibiotic Without FDA Breakpoints	Current Testing Method and Gaps Imposed by FDA Proposed Rule
Urgent threat
Carbapenem-resistant Acinetobacter	Polymyxins	Currently tested using an LDT. No testing possible under FDA proposed rule.
Candida auris	All antifungal agents	Currently tested using an LDT and interpreted using epidemiological cutoff values available from CDC and CLSI. No testing possible under FDA proposed rule.
Carbapenem-resistant Enterobacterales	Carbapenems	FDA breakpoints available for some members of the Enterobacterales group, but not all. Key exceptions include meropenem for Klebsiella aerogenes (ie, no FDA indication for meropenem against K. aerogenes). Currently tested using legacy devices or LDTs. Significantly reduced testing available under FDA proposed rule.
Drug-resistant Neisseria gonorrhoeae	Azithromycin	FDA rejected CLSI breakpoints. Testing not routinely performed outside public health laboratories, which use LDTs. No testing possible under FDA proposed rule.
Serious threat
Drug-resistant Campylobacter	All antimicrobial agents	Testing performed using LDTs with CLSI M45 breakpoints. No testing possible under FDA proposed rule.
Drug-resistant Candida	Amphotericin B	Testing performed using LDT that yields and MIC. No testing possible under FDA proposed rule.
VRE	Daptomycin	Testing performed using LDTs. No testing possible under FDA proposed rule.
MDR Pseudomonas	Cefiderocol	Testing performed using FDA breakpoints, which are more conservative than CLSI. Testing possible under proposed rule, but with significantly reduced susceptibility rates.
Drug-resistant nontyphoidal Salmonella	Azithromycin	Testing performed using LDTs. No testing possible under FDA proposed rule.
Drug-resistant Shigella	Azithromycin	Testing performed using LDTs. No testing possible under FDA proposed rule.
Drug-resistant Salmonella Typhi	Azithromycin	Testing performed using LDTs. No testing possible under FDA proposed rule.
MRSA	SXT, doxycycline	Testing performed using legacy devices or LDTs. No testing possible under FDA proposed rule.
Drug-resistant Streptococcus pneumoniae	Cefepime, vancomycin	Testing performed using legacy devices or LDTs. No testing possible under FDA proposed rule.
Drug-resistant tuberculosis	Isoniazid, rifampin, ethambutol, pyrazinamide	Testing performed using LDTs. No testing possible under FDA proposed rule.
Concerning threat
Erythromycin-resistant group A Streptococcus	Azithromycin	Testing performed using legacy devices or LDTs. No testing possible under FDA proposed rule.
Clindamycin-resistant group B Streptococcus	Azithromycin	Testing performed using legacy devices or LDTs. No testing possible under FDA proposed rule.
Watch list
Azole-resistant Aspergillus	Azole agents	Testing performed using LDTs. No testing possible under FDA proposed rule.
Drug-resistant Mycoplasma genitalium	All antimicrobials	Testing performed using LDTs. No testing possible under FDA proposed rule.
Drug-resistant Bordetella pertussis	All antimicrobials	Testing performed using LDTs. No testing possible under FDA proposed rule.

Threat Level

Antibiotic Without FDA Breakpoints

Current Testing Method and Gaps Imposed by FDA Proposed Rule

Urgent threat

Carbapenem-resistant Acinetobacter

Polymyxins

Currently tested using an LDT.
No testing possible under FDA proposed rule.

Candida auris

All antifungal agents

Currently tested using an LDT and interpreted using epidemiological cutoff values available from CDC and CLSI.
No testing possible under FDA proposed rule.

Carbapenem-resistant Enterobacterales

Carbapenems

FDA breakpoints available for some members of the Enterobacterales group, but not all. Key exceptions include meropenem for Klebsiella aerogenes (ie, no FDA indication for meropenem against K. aerogenes).
Currently tested using legacy devices or LDTs.
Significantly reduced testing available under FDA proposed rule.

Drug-resistant Neisseria gonorrhoeae

Azithromycin

FDA rejected CLSI breakpoints. Testing not routinely performed outside public health laboratories, which use LDTs.
No testing possible under FDA proposed rule.

Serious threat

Drug-resistant Campylobacter

All antimicrobial agents

Testing performed using LDTs with CLSI M45 breakpoints.
No testing possible under FDA proposed rule.

Drug-resistant Candida

Amphotericin B

Testing performed using LDT that yields and MIC.
No testing possible under FDA proposed rule.

VRE

Daptomycin

Testing performed using LDTs.
No testing possible under FDA proposed rule.

MDR Pseudomonas

Cefiderocol

Testing performed using FDA breakpoints, which are more conservative than CLSI.
Testing possible under proposed rule, but with significantly reduced susceptibility rates.

Drug-resistant nontyphoidal Salmonella

Azithromycin

Testing performed using LDTs.
No testing possible under FDA proposed rule.

Drug-resistant Shigella

Azithromycin

Testing performed using LDTs.
No testing possible under FDA proposed rule.

Drug-resistant Salmonella Typhi

Azithromycin

Testing performed using LDTs.
No testing possible under FDA proposed rule.

MRSA

SXT, doxycycline

Testing performed using legacy devices or LDTs.
No testing possible under FDA proposed rule.

Drug-resistant Streptococcus pneumoniae

Cefepime, vancomycin

Testing performed using legacy devices or LDTs.
No testing possible under FDA proposed rule.

Drug-resistant tuberculosis

Isoniazid, rifampin, ethambutol, pyrazinamide

Testing performed using LDTs.
No testing possible under FDA proposed rule.

Concerning threat

Erythromycin-resistant group A Streptococcus

Azithromycin

Testing performed using legacy devices or LDTs.
No testing possible under FDA proposed rule.

Clindamycin-resistant group B Streptococcus

Azithromycin

Testing performed using legacy devices or LDTs.
No testing possible under FDA proposed rule.

Watch list

Azole-resistant Aspergillus

Azole agents

Testing performed using LDTs.
No testing possible under FDA proposed rule.

Drug-resistant Mycoplasma genitalium

All antimicrobials

Testing performed using LDTs.
No testing possible under FDA proposed rule.

Drug-resistant Bordetella pertussis

All antimicrobials

Testing performed using LDTs.
No testing possible under FDA proposed rule.

Threat Level	Antibiotic Without FDA Breakpoints	Current Testing Method and Gaps Imposed by FDA Proposed Rule
Urgent threat
Carbapenem-resistant Acinetobacter	Polymyxins	Currently tested using an LDT. No testing possible under FDA proposed rule.
Candida auris	All antifungal agents	Currently tested using an LDT and interpreted using epidemiological cutoff values available from CDC and CLSI. No testing possible under FDA proposed rule.
Carbapenem-resistant Enterobacterales	Carbapenems	FDA breakpoints available for some members of the Enterobacterales group, but not all. Key exceptions include meropenem for Klebsiella aerogenes (ie, no FDA indication for meropenem against K. aerogenes). Currently tested using legacy devices or LDTs. Significantly reduced testing available under FDA proposed rule.
Drug-resistant Neisseria gonorrhoeae	Azithromycin	FDA rejected CLSI breakpoints. Testing not routinely performed outside public health laboratories, which use LDTs. No testing possible under FDA proposed rule.
Serious threat
Drug-resistant Campylobacter	All antimicrobial agents	Testing performed using LDTs with CLSI M45 breakpoints. No testing possible under FDA proposed rule.
Drug-resistant Candida	Amphotericin B	Testing performed using LDT that yields and MIC. No testing possible under FDA proposed rule.
VRE	Daptomycin	Testing performed using LDTs. No testing possible under FDA proposed rule.
MDR Pseudomonas	Cefiderocol	Testing performed using FDA breakpoints, which are more conservative than CLSI. Testing possible under proposed rule, but with significantly reduced susceptibility rates.
Drug-resistant nontyphoidal Salmonella	Azithromycin	Testing performed using LDTs. No testing possible under FDA proposed rule.
Drug-resistant Shigella	Azithromycin	Testing performed using LDTs. No testing possible under FDA proposed rule.
Drug-resistant Salmonella Typhi	Azithromycin	Testing performed using LDTs. No testing possible under FDA proposed rule.
MRSA	SXT, doxycycline	Testing performed using legacy devices or LDTs. No testing possible under FDA proposed rule.
Drug-resistant Streptococcus pneumoniae	Cefepime, vancomycin	Testing performed using legacy devices or LDTs. No testing possible under FDA proposed rule.
Drug-resistant tuberculosis	Isoniazid, rifampin, ethambutol, pyrazinamide	Testing performed using LDTs. No testing possible under FDA proposed rule.
Concerning threat
Erythromycin-resistant group A Streptococcus	Azithromycin	Testing performed using legacy devices or LDTs. No testing possible under FDA proposed rule.
Clindamycin-resistant group B Streptococcus	Azithromycin	Testing performed using legacy devices or LDTs. No testing possible under FDA proposed rule.
Watch list
Azole-resistant Aspergillus	Azole agents	Testing performed using LDTs. No testing possible under FDA proposed rule.
Drug-resistant Mycoplasma genitalium	All antimicrobials	Testing performed using LDTs. No testing possible under FDA proposed rule.
Drug-resistant Bordetella pertussis	All antimicrobials	Testing performed using LDTs. No testing possible under FDA proposed rule.

Threat Level

Antibiotic Without FDA Breakpoints

Current Testing Method and Gaps Imposed by FDA Proposed Rule

Urgent threat

Carbapenem-resistant Acinetobacter

Polymyxins

Currently tested using an LDT.
No testing possible under FDA proposed rule.

Candida auris

All antifungal agents

Currently tested using an LDT and interpreted using epidemiological cutoff values available from CDC and CLSI.
No testing possible under FDA proposed rule.

Carbapenem-resistant Enterobacterales

Carbapenems

Drug-resistant Neisseria gonorrhoeae

Azithromycin

FDA rejected CLSI breakpoints. Testing not routinely performed outside public health laboratories, which use LDTs.
No testing possible under FDA proposed rule.

Serious threat

Drug-resistant Campylobacter

All antimicrobial agents

Testing performed using LDTs with CLSI M45 breakpoints.
No testing possible under FDA proposed rule.

Drug-resistant Candida

Amphotericin B

Testing performed using LDT that yields and MIC.
No testing possible under FDA proposed rule.

VRE

Daptomycin

Testing performed using LDTs.
No testing possible under FDA proposed rule.

MDR Pseudomonas

Cefiderocol

Testing performed using FDA breakpoints, which are more conservative than CLSI.
Testing possible under proposed rule, but with significantly reduced susceptibility rates.

Drug-resistant nontyphoidal Salmonella

Azithromycin

Testing performed using LDTs.
No testing possible under FDA proposed rule.

Drug-resistant Shigella

Azithromycin

Testing performed using LDTs.
No testing possible under FDA proposed rule.

Drug-resistant Salmonella Typhi

Azithromycin

Testing performed using LDTs.
No testing possible under FDA proposed rule.

MRSA

SXT, doxycycline

Testing performed using legacy devices or LDTs.
No testing possible under FDA proposed rule.

Drug-resistant Streptococcus pneumoniae

Cefepime, vancomycin

Testing performed using legacy devices or LDTs.
No testing possible under FDA proposed rule.

Drug-resistant tuberculosis

Isoniazid, rifampin, ethambutol, pyrazinamide

Testing performed using LDTs.
No testing possible under FDA proposed rule.

Concerning threat

Erythromycin-resistant group A Streptococcus

Azithromycin

Testing performed using legacy devices or LDTs.
No testing possible under FDA proposed rule.

Clindamycin-resistant group B Streptococcus

Azithromycin

Testing performed using legacy devices or LDTs.
No testing possible under FDA proposed rule.

Watch list

Azole-resistant Aspergillus

Azole agents

Testing performed using LDTs.
No testing possible under FDA proposed rule.

Drug-resistant Mycoplasma genitalium

All antimicrobials

Testing performed using LDTs.
No testing possible under FDA proposed rule.

Drug-resistant Bordetella pertussis

All antimicrobials

Testing performed using LDTs.
No testing possible under FDA proposed rule.

Table 2.

Open in new tab

Gaps in US Food and Drug Administration–Recognized Antimicrobial Susceptibility Test Interpretive Criteria for US Centers for Disease Control and Prevention–Identified Antimicrobial Resistance Threats

Threat Level	Antibiotic Without FDA Breakpoints	Current Testing Method and Gaps Imposed by FDA Proposed Rule
Urgent threat
Carbapenem-resistant Acinetobacter	Polymyxins	Currently tested using an LDT. No testing possible under FDA proposed rule.
Candida auris	All antifungal agents	Currently tested using an LDT and interpreted using epidemiological cutoff values available from CDC and CLSI. No testing possible under FDA proposed rule.
Carbapenem-resistant Enterobacterales	Carbapenems	FDA breakpoints available for some members of the Enterobacterales group, but not all. Key exceptions include meropenem for Klebsiella aerogenes (ie, no FDA indication for meropenem against K. aerogenes). Currently tested using legacy devices or LDTs. Significantly reduced testing available under FDA proposed rule.
Drug-resistant Neisseria gonorrhoeae	Azithromycin	FDA rejected CLSI breakpoints. Testing not routinely performed outside public health laboratories, which use LDTs. No testing possible under FDA proposed rule.
Serious threat
Drug-resistant Campylobacter	All antimicrobial agents	Testing performed using LDTs with CLSI M45 breakpoints. No testing possible under FDA proposed rule.
Drug-resistant Candida	Amphotericin B	Testing performed using LDT that yields and MIC. No testing possible under FDA proposed rule.
VRE	Daptomycin	Testing performed using LDTs. No testing possible under FDA proposed rule.
MDR Pseudomonas	Cefiderocol	Testing performed using FDA breakpoints, which are more conservative than CLSI. Testing possible under proposed rule, but with significantly reduced susceptibility rates.
Drug-resistant nontyphoidal Salmonella	Azithromycin	Testing performed using LDTs. No testing possible under FDA proposed rule.
Drug-resistant Shigella	Azithromycin	Testing performed using LDTs. No testing possible under FDA proposed rule.
Drug-resistant Salmonella Typhi	Azithromycin	Testing performed using LDTs. No testing possible under FDA proposed rule.
MRSA	SXT, doxycycline	Testing performed using legacy devices or LDTs. No testing possible under FDA proposed rule.
Drug-resistant Streptococcus pneumoniae	Cefepime, vancomycin	Testing performed using legacy devices or LDTs. No testing possible under FDA proposed rule.
Drug-resistant tuberculosis	Isoniazid, rifampin, ethambutol, pyrazinamide	Testing performed using LDTs. No testing possible under FDA proposed rule.
Concerning threat
Erythromycin-resistant group A Streptococcus	Azithromycin	Testing performed using legacy devices or LDTs. No testing possible under FDA proposed rule.
Clindamycin-resistant group B Streptococcus	Azithromycin	Testing performed using legacy devices or LDTs. No testing possible under FDA proposed rule.
Watch list
Azole-resistant Aspergillus	Azole agents	Testing performed using LDTs. No testing possible under FDA proposed rule.
Drug-resistant Mycoplasma genitalium	All antimicrobials	Testing performed using LDTs. No testing possible under FDA proposed rule.
Drug-resistant Bordetella pertussis	All antimicrobials	Testing performed using LDTs. No testing possible under FDA proposed rule.

Threat Level	Antibiotic Without FDA Breakpoints	Current Testing Method and Gaps Imposed by FDA Proposed Rule
Urgent threat
Carbapenem-resistant Acinetobacter	Polymyxins	Currently tested using an LDT. No testing possible under FDA proposed rule.
Candida auris	All antifungal agents	Currently tested using an LDT and interpreted using epidemiological cutoff values available from CDC and CLSI. No testing possible under FDA proposed rule.
Carbapenem-resistant Enterobacterales	Carbapenems	FDA breakpoints available for some members of the Enterobacterales group, but not all. Key exceptions include meropenem for Klebsiella aerogenes (ie, no FDA indication for meropenem against K. aerogenes). Currently tested using legacy devices or LDTs. Significantly reduced testing available under FDA proposed rule.
Drug-resistant Neisseria gonorrhoeae	Azithromycin	FDA rejected CLSI breakpoints. Testing not routinely performed outside public health laboratories, which use LDTs. No testing possible under FDA proposed rule.
Serious threat
Drug-resistant Campylobacter	All antimicrobial agents	Testing performed using LDTs with CLSI M45 breakpoints. No testing possible under FDA proposed rule.
Drug-resistant Candida	Amphotericin B	Testing performed using LDT that yields and MIC. No testing possible under FDA proposed rule.
VRE	Daptomycin	Testing performed using LDTs. No testing possible under FDA proposed rule.
MDR Pseudomonas	Cefiderocol	Testing performed using FDA breakpoints, which are more conservative than CLSI. Testing possible under proposed rule, but with significantly reduced susceptibility rates.
Drug-resistant nontyphoidal Salmonella	Azithromycin	Testing performed using LDTs. No testing possible under FDA proposed rule.
Drug-resistant Shigella	Azithromycin	Testing performed using LDTs. No testing possible under FDA proposed rule.
Drug-resistant Salmonella Typhi	Azithromycin	Testing performed using LDTs. No testing possible under FDA proposed rule.
MRSA	SXT, doxycycline	Testing performed using legacy devices or LDTs. No testing possible under FDA proposed rule.
Drug-resistant Streptococcus pneumoniae	Cefepime, vancomycin	Testing performed using legacy devices or LDTs. No testing possible under FDA proposed rule.
Drug-resistant tuberculosis	Isoniazid, rifampin, ethambutol, pyrazinamide	Testing performed using LDTs. No testing possible under FDA proposed rule.
Concerning threat
Erythromycin-resistant group A Streptococcus	Azithromycin	Testing performed using legacy devices or LDTs. No testing possible under FDA proposed rule.
Clindamycin-resistant group B Streptococcus	Azithromycin	Testing performed using legacy devices or LDTs. No testing possible under FDA proposed rule.
Watch list
Azole-resistant Aspergillus	Azole agents	Testing performed using LDTs. No testing possible under FDA proposed rule.
Drug-resistant Mycoplasma genitalium	All antimicrobials	Testing performed using LDTs. No testing possible under FDA proposed rule.
Drug-resistant Bordetella pertussis	All antimicrobials	Testing performed using LDTs. No testing possible under FDA proposed rule.

Abbreviations: CDC, Centers for Disease Control and Prevention; CLSI, Clinical and Laboratory Standards Institute; FDA, US Food and Drug Administration; LDT, laboratory-developed test; MDR, multidrug-resistant; MIC, minimum inhibitory concentration; MRSA, methicillin-resistant Staphylococcus aureus; SXT, trimethoprim-sulfamethoxazole; VRE, vancomycin-resistant enterococci.

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