Antimicrobial Susceptibility

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Antibiotic Resistance Laboratory Network detects and contains emerging antibiotic resistanceARLab LogoFINAL rgb no tagline

Detection of antibiotic resistance is vital to proper treatment and containment of potential outbreaks. The Antibiotic Resistance (AR) Laboratory Network connects healthcare facilities, state and local labs, and CDC to quickly identify and contain drug-resistance before it can spread. Learn more about the AR Lab Network in a free webinar, summarized on the latest Bugs and Drugs.

Remember the major news story about the drug-resistant Pseudomonas aeruginosa outbreak in a skilled nursing facility? You don't, because the hard-to-treat isolate was detected and contained before it could spread. This is one of the success stories from the new Antibiotic Resistance Laboratory Network (AR Lab Network), a nationwide system to rapidly detect antibiotic resistance in healthcare, food, and the community.

As part of the webinar, Massimo Pacilli of the Chicago Department of Public Health (CDPH) will present the case above. Once ventilated patients were diagnosed with a P. aeruginosa infection, collaborations between the CDPH, the Centers for Disease Control and Prevention (CDC), the AR Lab Network regional lab in Wisconsin, and academic partners helped quickly identify the strain as one producing an uncommon and dangerous carbapenemase (Verona integron-encoded metallo-beta-lactamase, or VIM). This swift identification allowed for a rapid response to contain the spread of the microbe. According to Pacilli, "CDPH's success in controlling the outbreak relied heavily on the increased ability to conduct surveillance testing provided by AR Lab Network."

The AR Lab Network testing plays a critical role in CDC's containment strategy to prevent the spread of new or rare kinds of antibiotic resistance. Through testing done in labs in 50 states, five cities, and Puerto Rico, including seven regional labs, the nation can track changes in resistance so that local public health workers can more quickly identify and respond to outbreaks. The AR Lab Network regional labs can perform tests such as DNA sequencing that may not be available at every state and local lab.

How does ARLN surveillance testing work? This will be covered by two additional experts, David Warshauer of the Wisconsin State Lab of Hygiene and Massimo Pacilli from CDPH will discuss their local experiences with the AR Lab Network. Join the webinar to hear more about the types of isolates requested from clinical lab partners, how isolates are tested, and how isolates should be submitted to state and local health departments.

The ability to quickly identify resistant isolates is essential for proper therapy and to implement additional measures to prevent its spread wherever identified. State and local labs can help healthcare facilities test and characterize bacterial and fungal resistance, like the emerging threat Candida auris. Detection of resistance initiates collaboration between the state and regional labs and the lab where the isolate was found, to determine potential transmission routes, setting the stage for intervention from the local public health officials.

Early detection and rapid response can keep drug resistance from spreading to other patients, healthcare workers, or community members—which also helps keep its discovery out of the headlines. "No news is good news," as the saying goes, and this team of healthcare workers, clinical microbiologists, epidemiologists, and public health officials are hard at work to keep drug-resistance outbreaks out of the headlines.

Do you want to learn more about the AR Lab Network? Past webinars are free and available for viewing here.


Germs with Unusual Antibiotic Resistance Widespread in the U.S.
Ramped-up CDC strategy helps providers stop spread of new threats, prevents large outbreaks

Health departments working with the CDC's Antibiotic Resistance (AR) Laboratory Network found more than 220 instances of germs with "unusual" antibiotic resistance genes in the United States last year, according to the Vital Signs report published today by the Centers for Disease Control and Prevention (CDC).

Germs with unusual antibiotic resistance include those that:

  • Are resistant to all or most antibiotics tested, making them hard to treat, and
  • Are uncommon in a geographic area or the U.S., or
  • Have specific genes that allow them to spread their resistance to other germs.

More than 23,000 Americans die each year from infections caused by germs resistant to antibiotics. New data suggest that implementing CDC's containment strategy can prevent thousands of these infections. This containment strategy includes: rapid identification of resistance, infection control assessments, testing patients without symptoms who may carry and spread the germ, coordinated response, and continued assessments.

The containment strategy complements CDC's foundational efforts and is part of CDC's Antibiotic Resistance Solutions Initiative. Recent nationwide investments to states in lab, infection control, and response infrastructure are enabling rapid and aggressive investigations to keep resistance from spreading in health care settings. Together, these actions can address urgent threats, including Candida auris and certain types of "nightmare bacteria" such as carbapenem-resistant Enterobacteriaceae (CRE).

State and local health departments can improve outcomes by:

  • Making sure all health care facilities know what state and local lab support is available and what germs to send for testing, and developing a plan to respond rapidly.
  • Assessing the quality and consistency of infection control in health care facilities across the state.
  • Coordinating with affected health care facilities, the new AR Lab Network regional labs, and CDC for every case of unusual resistance.
  • Providing timely lab results and recommendations to affected health care facilities and providers.

CDC and other federal partners are working to improve outcomes by:

  • Monitoring resistance and sounding the alarm when threats emerge. CDC develops and provides new lab tests so health departments can quickly identify new threats.
  • Improving identification through CDC's new AR Lab Network in all 50 states, 5 large cities, and
  • Puerto Rico, including 7 regional labs and a national tuberculosis lab for specialty testing.
  • Supporting prevention experts and programs in every state, and providing data and recommendations for local prevention and response.
  • Testing innovative infection control and prevention strategies with health care and academic partners.

Please visit the CDC site for more information on How CDC is supporting efforts in your state to combat antibiotic resistance.
For additional questions, contact Jane Bigham at  This email address is being protected from spambots. You need JavaScript enabled to view it. .




Phenotypic Detection of β-Lactamase Resistance in Gram-Negative Bacilli: Testing and Interpretation Guide
To detect isolates with AmpC, K1, and KPC enzymes, as well as those with ESBLs, it is desirable to test all Enterobacteriaceae with a combination of antibiotics that will allow detection of resistant mechanisms. In Dr. Paul Schreckenberger's laboratory, he and Violeta Rekasius, MT(ASCP) have expanded the ESBL confirmatory disk test to include 12 antibiotic disks and have applied the test to all members of the Enterobacteriaceae that have a susceptibility pattern that is suspicious for the presence of an ESBL, AmpC, K1 or KPC type resistance gene. Through the application of this test they have been able to successfully detect antibiotic resistance in many species of Enterobacteriaceae that would have not been detected using their automated susceptibility testing system.