Dirty Dozen: Here Are the World’s Most Dangerous Bacteria


The World Health Organization (WHO) has released a kind of “Most Wanted” list for the world’s most dangerous pathogens.

They are a veritable deadly dozen of bacteria for which antibiotics have no impact.

“This list is a new tool to ensure R&D (research and development) responds to urgent public health needs,” Dr. Marie-Paule Kieny, WHO’s Assistant Director-General for health systems and innovation, described in a news release. “Antibiotic resistance is growing, and we are fast running out of treatment options. If we leave it to market forces alone, the new antibiotics we most urgently need are not going to be developed in time.”

The list is divided into three parts based on need: Critical, high and medium.

This petri dish contains Acinetobacter bacteria. Credit: Iqbal Osman/Flickr, CC BY 2.0

The critical list includes three pathogens. Those are Acinetobacter, Pseudomonas and various Enterobacteria (including Klebsiella, E. coli, Serratia and Proteus. These bacteria often are found in hospitals and nursing homes, especially among patients who require ventilators and blood catheters. The bacteria cause blood infections and pneumonia, which can be deadly, particularly among already sick patients.

Even the strongest antibiotics cannot kill these bacteria, which have learned how to adapt to new environments (such as the intestines) and thrive. They even can pass along their genetic information to other bacteria, so that they, too, can remain hardy.

Related: Killer ‘Smart Bacteria’ Found to Wreak Havoc on the Gut

Although significant progress has [been] made in preventing some infection types, there is much more work to be done,” the U.S. Centers for Disease Control and Prevention (CDC) reports on its web page dedicated to information about hospital-acquired infections. “On any given day, about one in 25 hospital patients has at least one healthcare-associated infection.”

An intracellular look at Salmonella, a bacteria typically transmitted through food. Credit: AJCI/Flickr, CC BY-SA 2.0

The other bacteria on the WHO list (six listed as high priority, three listed as medium priority) include drug-resistant bacteria for diseases such as gonorrhea and salmonella. Gonorrhea is sexually transmitted, while salmonella enters the body via tainted food.

In July, the CDC sounded an alarm about the emerging threat of drug-resistant gonorrhea. “The confluence of emerging drug resistance and very limited alternative options for treatment creates a perfect storm for future gonorrhea treatment failure in the U.S.,” said Dr. Jonathan Mermin, director of the CDC’s National Center for HIV/AIDS, Viral Hepatitis, STD, and Tuberculosis Prevention, in a news release. “History shows us that bacteria will find a way to outlast the antibiotics we’re using to treat it. We are running just one step ahead in order to preserve the remaining treatment option for as long as possible.”

Here is a scanning electron micrograph of a human neutrophil ingesting Methicillin-Resistant Staphylococcus Aureus (MRSA). Image/Caption Credit: NIAID/Flickr, CC BY 2.0

The bacteria on the high priority list include enterococcus faecium, staphylococcus aureus, helicobacter pylori, campylobacter spp., salmonellae and Neisseria gonorrhoeae. The medium-priority list includes streptococcus pneumoniae, haemophilius incluenzae, and shigella spp.

“We need effective antibiotics for our health systems,” said Hermann Grohe, Federal Minister of Health for Germany, in the WHO news release. “We have to take joint action today for a healthier tomorrow. Therefore, we will discuss and bring the attention of the G20 to the fight against antimicrobial resistance. WHO’s first global priority pathogen list is an important new tool to secure and guide research and development related to new antibiotics.”


Related: Good Bacteria Can Limit E. Coli, Salmonella Infections

A professional journalist nearly 30 years, David Heitz started his career at the Quad-City Times in Davenport, Iowa before moving to Los Angeles. He led the Glendale News-Press to best small daily newspaper in the state (CNPA) as managing editor and also worked as executive news editor of the Press-Telegram. He worked briefly as deputy news editor of the Detroit News before returning to the Quad-Cities, where he has worked as a freelance medical writer since 2012 for several national websites. He recently purchased his childhood home and says he truly is “living the dream.”