Antibiotic Resistance

A Dire Need for Antibiotic Resistance Solutions

Multi-drug resistant (MDR) bacterial infections are becoming increasingly
common in the hospital and community setting, emphasizing the need for
new orally administered and IV antibiotics that can effectively treat
such infections. Spero Therapeutics seeks to address these unmet needs.

Combating Antibiotic Resistance Is a Constant Battle


Historically, antibiotics have saved millions of lives and eased the suffering of patients. They have been dubbed “wonder drugs” and deserve much of the credit for the dramatic increase in life expectancy in the U.S. and around the world; however, they are not always effective. Over time, bacteria can and have developed resistance to existing drugs, making infections difficult, if not impossible, to treat.

Both the Centers for Disease Control (CDC) and World Health Organization (WHO) have identified antibiotic resistance as an increasing threat to global public health. Additionally, world health leaders have stated that antibiotic-resistant microorganisms are “nightmare bacteria” that “pose a catastrophic threat” to people in every country in the world.

Among all of the bacterial resistance challenges, Gram-negative pathogens are particularly worrisome because they are becoming increasingly resistant to nearly every available antibiotic. The most serious Gram-negative infections are healthcare-associated, namely those caused by EnterobacteriaceaePseudomonas aeruginosa, and Acinetobacter baumannii, identified as posing serious to urgent threats to public health by the CDC.

A key challenge in treating these infections is that the number of new antibiotics developed and approved has steadily decreased in the past three decades, leaving fewer options to treat resistant bacteria. Only two new classes of antibiotics have been developed in the past 15 years, and it’s been more than 30 years since a new class of antibiotics to treat Gram-negative infections has emerged.(3)

Experiencing Increase in MDR Pathogens in the Community Settings

While a majority of life-threatening infections resulting from antibiotic-resistant bacteria are historically acquired in the hospital setting, there is a rising incidence of multi-drug resistant (MDR) pathogens in the community setting.  This has resulted in decreased susceptibility to standard oral options and an increase in avoidable hospitalizations, along with the costs and risks associated with this.

Currently, there are no oral antibiotics commercially available that can be used in adults with MDR Gram-negative bacterial infections. This limits the ability for physicians to treat these infections without hospitalizing their patients to receive IV antibiotics. In addition, not having an oral option at discharge often delays the transition of care from hospital to home.

The limitations of existing therapies and traditional drug development approaches highlights the critical need for novel therapies, and in particular orally-administered agents, that are capable of overcoming these obstacles to effective patient treatment.



According to the Center for Disease Control’s Antibiotic Resistance Threats in the United States, 2019 report, more than 2.8 million antibiotic-resistant infections occur in the U.S. each year, and more than 35,000 people die as a result. (1)

In the EU alone, Antimicrobial resistant infections are responsible for an estimated 33,000 deaths per year.  It is also estimated that antimicrobial resistance costs the EU EUR 1.5 billion per year in healthcare costs and productivity losses. (2)


“Spero Therapeutics was founded to address the serious infections and the growing global threat of antibiotic resistance through innovative therapeutic approaches.”

– Ankit Mahadevia, MD, President and CEO

Source: Food and Drug Administration (modified)

Presented by John H. Powers, MD, at April 15-16, 2004 “Antimicrobial Drug
Development Workshop,” co-sponsored by FDA, IDSA, and the International
Society of Anti-Infective Pharmacology.

External Resources

The following links from government agencies, medical societies and press are made available as additional sources of information on antimicrobial resistance, Gram-negative bacteria and infectious disease in general.

It is important to note that these external websites are not maintained nor sponsored by Spero. Further, Spero is not responsible for the availability or content of these external sites, nor does Spero endorse any of the products, opinions, services or information offered thereon.

  1. CDC AR Threats 2019 report, CDC website
  2. European Commission Website, Antimicrobial resistance,
  3. 3. Coates AR, Halls G, Hu Y. Novel classes of antibiotics or more of the same? British Journal of Pharmacology. 2011;163(1):184-194.