Antibiotics Appear to Worsen Flu Defenses, Study Shows

Millions of people around the world consume antibiotics indiscriminately. Unfortunately, this behavior can have serious health consequences. For example, according to studies, it may worsen your flu defenses.
Antibiotics Appear to Worsen Flu Defenses, Study Shows

Last update: 04 August, 2021

Antibiotics are drugs used in the treatment of bacterial infections. However, their indiscriminate administration can lead to the resistance of microorganisms. A recent study conducted in mice establishes that antibiotics appear to worsen flu defenses in the lungs.

The misuse of these microbicidal drugs has become a major problem for healthcare professionals. Worldwide, a large proportion of people use them in the ineffective management of inflammatory, traumatic, or viral conditions, without any medical supervision.

A group of scientists from the Francis Crick Institute has shown that antibiotics affect the first line of immune defense at the pulmonary level. In addition, it was shown that they alter the protein signaling promoted by intestinal bacteria, also influencing this aspect of the immune system.

Antibiotics and flu defenses: The study

At the beginning of the study, the research team used a group of laboratory rodents with healthy intestinal bacterial flora. First, these mice received a mixture of antibiotics diluted in drinking water for more than 3 weeks. After this time, the team infected the test group with the influenza virus.

On the other hand, the second group of control rodents that didn’t drink previous antibiotics was also infected with the virus. In this way, the researchers hoped to compare and analyze the results in detail. Only 2 days after infection, the antibiotic-treated mice had a viral population in their lungs five times higher than the control group.

In addition, the scientists decided to perform a fecal transplant on a small group of infected rodents that they’d previously treated with antibiotics. By doing so, they sought to repopulate the intestinal bacterial flora that the use of the drug had produced, to evaluate the role of protein signaling of bacterial origin in the restoration of pulmonary defenses.

The main focus of the research was to assess the dynamics of interferon in the pathogenesis of pulmonary viral infection. Throughout the research, it was possible to demonstrate how antibiotics not only seem to worsen flu defenses but also favor the development of more severe clinical pictures.

An elderly man with a blacked over his shoulders, coughing into his hand.
Influenza is a viral infection that doesn’t require antibiotics for its management, except when a bacterial superinfection is added, which isn’t always the case.

What did the results show regarding flu defenses?

This recent research describes how immunity in the human body depends on a complex intercellular and intracellular signaling process. It involves a system of protein stimuli originating from intestinal bacteria, which prepare the tissues for defense.

The results of the study confirm that antibiotics worsen the clinical course of those infected by the influenza virus by altering signaling. In this regard, 80% of infected rodents with healthy bacterial flora managed to survive. However, more than 60 % of the mice that received previous antibiotics died during the study.

At the same time, a better immune response to the infection was achieved after repopulating the intestinal bacterial flora in the infected rodents. In this way, the test mice developed a better defense against the virus attack and obtained a better survival rate. This fact highlights how antibiotics worsen flu defenses on a pulmonary and systemic level.

Influence of intestinal flora on pulmonary immunity

The indiscriminate use of antibiotics favors the reduction of useful intestinal bacterial populations. And this leaves the body vulnerable to viral lung infections. This discovery is of vital importance, not only in human clinical practice, but also in the approach to prophylactic antimicrobial therapies in animal husbandry and agriculture.

The research also revealed that type I interferon is the molecule responsible for signaling and regulating pulmonary defenses. This substance is responsible for stimulating the early pulmonary response to viral multiplication, reducing the rate of infection and colonization.

Interferon promotes the activation of MX1 antiviral genes in rodents, equivalent to the MxA gene in humans. And these participate in altering the replication and survival of viruses in the organism.

The cells lining the lung tissue are the first link of defense against harmful agents. Therefore, as intestinal bacterial signaling is present, activator genes warn and prime them, thus reducing viral colonization. However, antibiotics reduce type I interferon and worsen the clinical course of influenza.

A digital image of infection running through the body.
The lungs are an initial barrier against infections that reach the body via the respiratory tract. Their effectiveness depends on certain genetic activations.

Read also: The Flu Vaccine

Flu defenses can stabilize again

A determining factor throughout this research was the possibility of restoring the lungs’ immune system to its original state. To this end, the researchers opted to perform fecal transplantation in the rodents. This allowed the intestinal flora to repopulate and return to normal.

So, they improved the local immunity in the lungs and boosted defenses in other tissues. At the same time, further studies in humans are still necessary to demonstrate the efficacy of the procedure or the need for other approaches.

You should never take antibiotics without a doctor’s prescription

To conclude, this new study claiming that antibiotics appear to worsen flu defenses isn’t something we should take lightly.

Viral infections should be treated with antivirals or supportive methods only. After all, antibiotic drugs haven’t shown any efficacy in this context. In addition, there’s a dramatic increase in bacterial resistance and a long list of adverse effects having to do with consumption.

In this regard, you should never take these drugs or any other medication without a doctor’s prescription. Health professionals are the only ones qualified to evaluate the condition, identify the conditions, and suggest the best therapeutic approach.

It might interest you...
How Antibiotics Work for Urinary Tract Infections
Step To HealthRead it in Step To Health
How Antibiotics Work for Urinary Tract Infections

Antibiotics are used to treat UTIs because, most of the time, the causative agents are bacteria. Here, discover how antibiotics work for UTIs.

  • Bradley K, Finsterbusch K, Schnepf D, Crotta S, Llorian M, Davidson S et al. Microbiota-Driven Tonic Interferon Signals in Lung Stromal Cells Protect from Influenza Virus Infection. Cell Reports. 2019;28(1):245-256.e4.
  • Havers FP, Hicks LA, Chung JR, Gaglani M, Murthy K, Zimmerman RK et al. Outpatient Antibiotic Prescribing for Acute Respiratory Infections During Influenza Seasons. JAMA Netw Open. 2018 Jun 1;1(2):e180243.
  • Belkina T, Al Warafi A, Hussein Eltom E, Tadjieva N, Kubena A, Vlcek J. Antibiotic use and knowledge in the community of Yemen, Saudi Arabia, and Uzbekistan. J Infect Dev Ctries. 2014 Apr 15;8(4):424-9.
  • Pestka S, Krause CD, Walter MR. Interferons, interferon-like cytokines, and their receptors. Immunol Rev. 2004 Dec;202:8-32.
  • Pichlmair A, Pollak M, Bergthaler A. Die erste Antwort auf virale Infektionen: Typ I Interferone [The first answer to viral infections: type I interferon]. Berl Munch Tierarztl Wochenschr. 2004 Jul-Aug;117(7-8):252-65.
  • Rönnblom L. The importance of the type I interferon system in autoimmunity. Clin Exp Rheumatol. 2016 Jul-Aug;34(4 Suppl 98):21-4.