Lab Matters Spring 2017 - Page 28

infectious diseases

Gono-Caucus 2017 : Defining Multi-Drug Resistant Neisseria gonorrhoeae

by Anne M . Gaynor , PhD , manager , HHST

Gonorrhea ’ s colloquial nickname —“ The Clap ”— may suggest a less-thanserious infection , but the continued emergence of multi-drug resistant strains and the dwindling list of potential treatment options heighten global concern for the potential of untreatable infections that lead to severe sequelae . In 2013 the US Centers for Disease Control and Prevention ( CDC ) 1 classified drug-resistant Neisseria gonorrhoeae as one of three pathogens at “ Threat Level : Urgent ” based on the nearly 30 % of strains of N . gonorrhoeae that are resistant to at least one antibiotic . It was also recognized as a pathogen of concern in a 2014 World Health Organization Report 2 and by the US White House in the National Action Plan for Combating Antibiotic Resistant Bacteria ( CARB ). 3

A final report of Gono-Caucus 2017 will be published in the future by APHL along with all of the presentations . The report will include a more complete summary , including the associated antibiotics . A public comment period on proposed changes will follow .
N . gonorrhoeae continues to develop resistance to the antibiotics used for treatment , necessitating ongoing surveillance of drug-resistance to inform treatment recommendations . Antimicrobial resistance acquired by N . gonorrhoeae tends to remain within the microbial population even in the absence of selective antimicrobial pressure . The terms “ multidrug resistant ” ( MDR ) and “ extensively drug resistant ” ( XDR ) have been used to describe N . gonorrhoeae that have become resistant to more than one class of antimicrobial agents . However , the classification of N . gonorrhoeae resistant phenotypes into MDR- or XDR- N . gonorrhoeae is complicated by changing treatment options that reflect the evolution of antimicrobial resistance . While there is a standardized classification scheme , 4 the use of the terms MDR and XDR have been inconsistent .
APHL , in collaboration with the CDC Division of STD Prevention , hosted Gono-Caucus 2017 in early January to bring together experts in the field of N . gonorrhoeae antimicrobial resistance to better define and discuss communication strategies involving standardized MDR and XDR definitions . The first day covered the current definitions of MDR bacteria used for other healthcare-associated infections and tuberculosis , implications of MDR N . gonorrhoeae , as well as data trends from the US and international surveillance systems of MDR N . gonorrhoeae , and genetic mutations associated with drugresistance . The second day moved to topics such as identifying treatment failures , drug distribution and penetration in various anatomic sites , the role of minimum inhibitory concentration ( MIC ) and its potential relevance to clinical outcomes , and clinical and public health responses to MDR N . gonorrhoeae . Discussion points included the standardization of MIC values used to define drug-resistance , the potential value of categorical resistance or use of terms such as “ reduced susceptibility ,” and the importance of a classification scheme that can be clearly and succinctly conveyed to Congress , the media , the US public , healthcare providers and laboratorians .
At the conclusion of the meeting , participants came up with two proposals for a classification scheme . Groups were asked to clearly and succinctly state their proposal for both MDR and XDR classification . In developing these proposals , the following topics were discussed :
• Inclusion and / or the role of genetic or genotypic data
• Potential changes in antimicrobial breakpoints ( which vary by country and by regulatory / oversight body ) or methodology to detect resistance
• Flexibility to address new or changing treatment recommendations
• The varied ability and usage of certain antibiotics .
Current and Proposed New Multi-Drug Resistant Classifications
Current 4 Proposal : New Proposal 2 : Modified Tapsall 4
MDR
Isolate has phenotypic resistance to one antimicrobial agent in category I and at least two in category II
Isolate has phenotypic resistance to at least two antimicrobial agents being assessed for surveillance . * If penicillin and tetracycline are tested , then MDR would require resistance to four antimicrobial agents
Isolate has phenotypic resistance to two antimicrobial agents currently recommended for treatment in category I and at least two antimicrobial agents less frequently used for treatment due to emerging resistance .
XDR
Isolate has phenotypic resistance to two antimicrobial agents in category I and at least two in category II
Term not used
Isolate has phenotypic resistance to two antimicrobial agents currently recommended for treatment and at least two antimicrobial agents less frequently used for treatment due to emerging resistance .
Potential Outcomes N / A
Initial modeling indicates that the definition would result in stable level of MDR-GC over time . a
Initial modeling indicates that the definition would result in an increase in MDR-GC isolates over time . a
a . Trends in N . gonorrhoeae antimicrobial resistance demonstrate few remaining treatment options and increasing numbers of isolates resistant to multiple antimicrobial agents
References 1 . Centers for Disease Control and Prevention . Antibiotic Resistance Threats in the United States , 2013 . Available at : https :// www . cdc . gov / drugresistance / pdf / ar-threats-2013-508 . pdf 2 . World Health Organization . Antimicrobial Resistance : Global Report on Surveillance . 2014 . Available at : http :// apps . who . int / iris / bitstream / 10665 / 112642 / 1 / 9789241564748 _ eng . pdf
3 . Task Force for Combating Antibiotic-Resistant Bacteria . National Action Plan to Combat Antibiotic-Resistant Bacteria . 2015 . Available at : https :// obamawhitehouse . archives . gov / sites / default / files / docs / national _ action _ plan _ for _ combating _ antibotic-resistant _ bacteria . pdf
4 . Tapsall JW , Ndowa F , Lewis DA , Unemo M . Meeting the public health challenge of multidrug-and extensively drug-resistant Neisseria gonorrhoeae . Expert Rev Anti Infect Ther ., 2009:7 ( 7 ); 821-834
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LAB MATTERS Spring 2017
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