Featured Research

from universities, journals, and other organizations

Long antibiotic treatments: Slowly growing bacteria to blame

Date:
August 14, 2014
Source:
University of Basel
Summary:
Whether pneumonia or sepsis, infectious diseases are becoming increasingly difficult to treat. One reason for this is the growing antibiotic resistance. But even non-resistant bacteria can survive antibiotics for some time, and that's why treatments need to be continued for several days or weeks. Scientist have now shown that bacteria with vastly different antibiotic sensitivity coexist within the same tissue. They report that, in particular, slowly growing pathogens hamper treatment.

This image shows infected mouse spleen containing fast (green) and slow (orange) growing Salmonella (blue: nuclei of mouse cells).
Credit: Illustration: University of Basel, Biozentrum

Whether pneumonia or sepsis -- infectious diseases are becoming increasingly difficult to treat. One reason for this is the growing antibiotic resistance. But even non-resistant bacteria can survive antibiotics for some time, and that's why treatments need to be continued for several days or weeks. Scientists at the Biozentrum of the University of Basel showed that bacteria with vastly different antibiotic sensitivity coexist within the same tissue. In the scientific journal Cell they report that, in particular, slowly growing pathogens hamper treatment.

Many bacteria are principally susceptible to treatment, but can still survive for some hours to days in adverse environmental conditions, such as exposure to antibiotics. It is commonly assumed that these pathogens are in a type of "dormancy" state. They don't grow and thus become invulnerable against the effects of many antibiotics. However, Prof. Dirk Bumann and his team at the University of Basel's Biozentrum, demonstrated that dormant pathogens play only a minor role in Salmonella-infected tissue. Instead, abundant slowly growing bacteria are the biggest challenge for treatment.

Salmonella Grows at Different Rates

Genetically identical bacteria can grow at very different rates, even within the same test tube. Is this also true for pathogens in infected host tissues? Bumann used a new method based on fluorescent colors, to measure the proliferation of individual Salmonella. The results revealed that in host tissues some Salmonella grow very rapidly, producing many daughter cells, which cause increasingly severe disease. Most bacteria, however, reside in tissue regions with limited nutrient supply, in which they grow only slowly.

Slow Growth Ensures Survival

How do these diverse growth rates impact on the success of antibiotic therapy? Therapy of infected mice quickly ameliorated disease signs, but even after five days of treatment, some bacteria still survived in the tissues, posing a risk for relapse. "We could kill already 90 percent of the Salmonella with the first antibiotic dose, particularly those that grew rapidly," reports Bumann, "but non-growing Salmonella survived much better. Treatment success thus depended on the Salmonella replication rate."

This observation could support the current research focus on "dormant" bacteria. However, Bumann was surprised that such bacteria were actually not the biggest challenge for treatment. "Instead, slowly growing Salmonella are more important. They tolerate antibiotics less well compared to dormant bacteria, but they are present in much larger numbers, and readily restart their growth once antibiotic levels in the tissue drop, thus driving infection and relapse. As a result, slowly growing pathogens dominate throughout the entire therapy. A better understanding of bacterial physiology of such slowly growing bacteria, could help us to shorten the duration of treatment with a more specifically targeted antibiotic therapy." This is particularly interesting for infectious diseases that currently require medication over several weeks or even months, to prevent a recurrence of the infection.


Story Source:

The above story is based on materials provided by University of Basel. Note: Materials may be edited for content and length.


Journal Reference:

  1. Beatrice Claudi, Petra Sprφte, Anna Chirkova, Nicolas Personnic, Janine Zankl, Nura Schόrmann, Alexander Schmidt, Dirk Bumann. Phenotypic Variation of Salmonella in Host Tissues Delays Eradication by Antimicrobial Chemotherapy. Cell, 2014; 158 (4): 722 DOI: 10.1016/j.cell.2014.06.045

Cite This Page:

University of Basel. "Long antibiotic treatments: Slowly growing bacteria to blame." ScienceDaily. ScienceDaily, 14 August 2014. <www.sciencedaily.com/releases/2014/08/140814124449.htm>.
University of Basel. (2014, August 14). Long antibiotic treatments: Slowly growing bacteria to blame. ScienceDaily. Retrieved October 2, 2014 from www.sciencedaily.com/releases/2014/08/140814124449.htm
University of Basel. "Long antibiotic treatments: Slowly growing bacteria to blame." ScienceDaily. www.sciencedaily.com/releases/2014/08/140814124449.htm (accessed October 2, 2014).

Share This



More Plants & Animals News

Thursday, October 2, 2014

Featured Research

from universities, journals, and other organizations


Featured Videos

from AP, Reuters, AFP, and other news services

Attacking Superbugs

Attacking Superbugs

Ivanhoe (Oct. 1, 2014) — Two weapons hospitals can use to attack superbugs. Scientists in Ireland created a new gel resistant to superbugs, and a robot that can disinfect a room in minutes. Video provided by Ivanhoe
Powered by NewsLook.com
Cultural Learning In Wild Chimps Observed For The First Time

Cultural Learning In Wild Chimps Observed For The First Time

Newsy (Oct. 1, 2014) — Cultural transmission — the passing of knowledge from one animal to another — has been caught on camera with chimps teaching other chimps. Video provided by Newsy
Powered by NewsLook.com
Earth Has Lost Half Its Vertebrate Wildlife Since 1970: WWF

Earth Has Lost Half Its Vertebrate Wildlife Since 1970: WWF

Newsy (Sep. 30, 2014) — A new study published by the World Wide Fund for Nature found that more than half of the world's wildlife population has declined since 1970. Video provided by Newsy
Powered by NewsLook.com
Annual Dog Surfing Competition Draws California Crowds

Annual Dog Surfing Competition Draws California Crowds

AFP (Sep. 30, 2014) — The best canine surfers gathered for Huntington Beach's annual dog surfing competition, "Surf City, Surf Dog." Duration: 01:15 Video provided by AFP
Powered by NewsLook.com

Search ScienceDaily

Number of stories in archives: 140,361

Find with keyword(s):
 
Enter a keyword or phrase to search ScienceDaily for related topics and research stories.

Save/Print:
Share:  

Breaking News:

Strange & Offbeat Stories

 

Plants & Animals

Earth & Climate

Fossils & Ruins

In Other News

... from NewsDaily.com

Science News

Health News

Environment News

Technology News



Save/Print:
Share:  

Free Subscriptions


Get the latest science news with ScienceDaily's free email newsletters, updated daily and weekly. Or view hourly updated newsfeeds in your RSS reader:

Get Social & Mobile


Keep up to date with the latest news from ScienceDaily via social networks and mobile apps:

Have Feedback?


Tell us what you think of ScienceDaily -- we welcome both positive and negative comments. Have any problems using the site? Questions?
Mobile iPhone Android Web
Follow Facebook Twitter Google+
Subscribe RSS Feeds Email Newsletters
Latest Headlines Health & Medicine Mind & Brain Space & Time Matter & Energy Computers & Math Plants & Animals Earth & Climate Fossils & Ruins