MAR 22, 2022 7:57 AM PDT

When Different Microbes are Present, Antibiotics are Less Effective

WRITTEN BY: Carmen Leitch

Although antibiotic resistance is becoming a problem, many bacterial infections can still be prevented or eliminated with antibiotic drugs. But new research has shown that those drugs become less effective when multiple types of microbes are present, even at very low levels. This study can help explain why lung disease patients, including those with cystic fibrosis, can be so difficult to eliminate. The findings, which have been reported in The ISME Journal, demonstrate the importance of considering microbial interactions when using antibiotics to treat infections.

A (cropped) 20,000X magnification of a digitally colorized SEM image of Staphylococcus aureus bacteria (yellow) in the process of attempting to escape destruction by human white blood cells (blue). / Credit: Frank DeLeo, National Institute of Allergy and Infectious Diseases (NIAID)

Co-infections with multiple pathogens aren't unusual in patents with chronic infections, but those aren't typically taken into account when calculating dosages. So, the results of this study "might help explain why, in these people, the antibiotics just don't work as well as they should," said co-first study author Thomas O'Brien, Ph.D.

Antibiotics aren't particularly efficient when it comes to chronic airway infections, which are often dominated by one pathogen. However, other types of microbes, many that are typically harmless, can frequently be found at the infection site. Those other microbes now appear to be an important consideration.

In this study, a new model of airway infection was created to grow and sustain microbial cocktails for several weeks, which can be difficult to do in the lab. These 'poly-microbial infections' were generated with Pseudomonas aeruginosa and Staphylococcus aureus bacteria as well as Candida albicans fungus, which is a common combination of microbes found in cystic fibrosis patients. The antibiotic colistin was unable to destroy the mixture, though it usually can destroy colonies of P. aeruginosa. Similar results were seen with another antibiotic called fusidic acid that normally kills S. aureus, or fluconazole, which targets Candida. Much higher doses of each drug were required to eliminate these microbes when they were part of a poly-microbial infection compared to single microbial colonies.

"All three species-specific antibiotics were less effective against their target when three pathogens were present together," said senior study author Martin Welch, Professor of Microbial Physiology and Metabolism at the University of Cambridge.

Antibiotics are usually tested to identify the lowest dose needed to effectively stop an infection. This study shows why those lab-tested doses don't always work when applied to a person. But the poly-microbial infection model used in this study can help determine the correct dose.

Sources: University of Cambridge, ISME Journal

About the Author
BS
Experienced research scientist and technical expert with authorships on over 30 peer-reviewed publications, traveler to over 70 countries, published photographer and internationally-exhibited painter, volunteer trained in disaster-response, CPR and DV counseling.
You May Also Like
MAY 15, 2022
Immunology
Long-Term Antibiotics Raise the Risk of Death From a Systemic Fungal Infection
MAY 15, 2022
Long-Term Antibiotics Raise the Risk of Death From a Systemic Fungal Infection
Infections are common, and many are becoming increasingly hard for clinicians to treat. Antibiotics are often used to tr ...
JUN 04, 2022
Immunology
Deciphering the Signals Between Invaders & Immune Cells
JUN 04, 2022
Deciphering the Signals Between Invaders & Immune Cells
Our immune system is a crucial, and has to be ready to respond to a variety of external threats that we are constantly e ...
JUN 29, 2022
Microbiology
Unleashing the Genetic Power of Ocean Microbes
JUN 29, 2022
Unleashing the Genetic Power of Ocean Microbes
By analyzing over 1,000 samples of the marine environment, researchers have reconstructed the genomes of 25,000 novel mi ...
JUL 08, 2022
Microbiology
Good Bacteria in the Urinary Tract Can Eliminate Pathogens
JUL 08, 2022
Good Bacteria in the Urinary Tract Can Eliminate Pathogens
Bacteria are everywhere, even in our bodies. While some might be dangerous, many have beneficial, positive roles. Resear ...
JUL 20, 2022
Microbiology
Halting the Assembly of Dangerous Paramyxoviruses Like Nipah
JUL 20, 2022
Halting the Assembly of Dangerous Paramyxoviruses Like Nipah
The paramyxovirus includes serious pathogens that can cause pandemics, including ones that lead primarily to mild. Illne ...
JUL 28, 2022
Technology
Using Bacteria to Make Rocket Fuel
JUL 28, 2022
Using Bacteria to Make Rocket Fuel
A recent study conducted by a team of biofuel experts at Lawrence Berkeley National Laboratory (Berkeley Lab) and publis ...
Loading Comments...