Some statistics: acute respiratory infections (ARI) account for 97% of all infectious diseases, and every third person goes to the doctor with complaints about these diseases. But for correct therapy, it is important to understand what the cause of the disease is. In this article, we will figure out how to understand whether you have a viral or bacterial infection, and what is the difference between these two conditions.
Some statistics: acute respiratory infections (ARI) account for 97% of all infectious diseases, and every third person goes to the doctor with complaints about these diseases. 1 But for correct therapy, it is important to understand the cause of the disease. In this article, we will figure out how to understand whether you have a viral or bacterial infection, and what is the difference between these two conditions.
Differences between bacteria and viruses
Bacteria and viruses are often grouped together as microbes. In fact, these microorganisms differ greatly in structure, reproduction and nutrition methods, and stability outside the body.
|
|
Bacteria |
Viruses |
|
Cellular structure |
Eat |
No |
|
Organelles |
Eat |
No |
|
DNA or RNA |
Both DNA and RNA |
DNA or RNA |
|
The ability to live and reproduce outside the body of an animal or human |
Yes |
No |
|
Volatility |
Tall |
Very high |
In essence, a virus is a multitude of molecules. But after entering the body, it behaves like a living object: it integrates into cells and multiplies – it parasitizes. 2
Bacteria are a full-fledged organism, only very small. Bacteria have their own life support systems, which are called organelles, they are able to live in the external environment – soil, water, food. They can even be affected by bacteriophage viruses.
How to distinguish a viral infection from a bacterial one
In 90% of cases, respiratory infections are caused by viruses. Bacteria cause ARI in only 10% of cases. However, a viral infection can be combined with a bacterial one. 3 It is necessary to determine exactly what caused the disease in order to choose an effective treatment.
The main difference between a viral infection and a bacterial infection is the pathogen. The most common pathogens of respiratory viral infections 4 :
- influenza virus;
- parainfluenza virus;
- respiratory syncytial virus;
- rhinoviruses;
- adenoviruses ;
- coronaviruses;
- metapneumoviruses;
- bocaviruses;
- Coxsackie virus ;
- Epstein-Barr virus.
Of the bacteria that cause respiratory infections, opportunistic ones are more common, that is, those that normally live on the human body. If the disease is caused by pathogenic bacteria, it is more severe. 9 Most common pathogens of bacterial infections: 10
- Staphylococcus aureus;
- methicillin-resistant Staphylococcus aureus 7 ;
- β-hemolytic streptococcus group A;
- pneumococcus;
- emophilus bacillus;
- Moraxella;
- chlamydia;
- mycoplasmas.
You can tell whether a person has a bacterial or viral infection based on the clinical picture. 12
|
|
Viral infection |
Bacterial infection |
|
Consistency of mucus from the nasal cavity |
At the initial stage it is transparent and liquid, then it can become thick. |
Thick, yellow-green or bright green, may be mixed with rust |
|
Cough |
At the initial stage – dry, then the sputum is transparent, in small quantities |
At the initial stage it can be dry, but very quickly it turns into wet |
|
Temperature |
Depends on the disease: for flu and COVID-19 – 38.5 °C and above |
Depends on the disease and its stage; bacterial complications of acute respiratory viral infections and influenza are characterized by a repeated rise in temperature after previous normalization. |
|
Duration of fever |
Depends on the disease, but usually up to five days |
Depends on the disease and treatment approaches, but usually more than five days |
|
Neurological symptoms: headache, pain in the eyeballs, loss of smell |
Depends on the disease, for example, flu and COVID-19 are characterized by |
Depends on the disease, but most often they are not typical |
|
Damage to the ENT organs, as well as the sinuses – paranasal sinuses |
In the form of viral sinusitis – difficulty breathing, nasal congestion, loss of smell, clear discharge |
In the form of bacterial sinusitis – headache, often one-sided, feeling of heaviness in the head, loss of smell, thick, hard-to-separate yellow-green or green contents, pain in characteristic points when pressed |
|
Conjunctivitis |
Depends on the infection, most often occurs with acute respiratory viral infections and flu |
May occur as a concomitant lesion with sinusitis |
Diagnostic methods. How can you tell if a person has a viral or bacterial infection? Diagnostic tests are used to do this.
Diagnostics of viral infection is important during an epidemic or in the center of infection. In common situations (during the cold season, when there is a suspicion of an outbreak of an off-season infection) it is not mandatory, and is only needed by a doctor to determine the treatment tactics, especially in severe cases of the disease, or when it is necessary to decide on quarantine measures.
Please note that only a doctor can interpret the test results and the diagnosis is made based on a combination of laboratory data, the patient’s medical history, the history of his illness and the clinical picture that he observes during the examination of the patient.
Laboratory diagnostics include:
- PCR for a specific pathogen (indicated by the doctor);
- determination of antigens of viral or bacterial infection in the blood;
- analysis of sputum (discharge from the nose or paranasal sinuses), including smear microscopy and sometimes bacteriological examination;
- determination of markers of bacterial inflammation in a biochemical blood test – C-reactive protein (CRP), procalcitonin, fibrinogen;
- determination in a general blood test of signs indicating the presence of inflammation: increased ESR and leukocyte levels, changes in the leukocyte formula, etc.
When examining a patient, a doctor may suspect a bacterial infection of the ENT organs if the following local symptoms are observed during examination: 13
- When examining the nasal cavity, thick yellow-green mucus is visible;
- there are purulent plugs on the tonsils;
- There is a small red rash on the upper palate.
In case of a bacterial infection, bacteria or even fungal pathogens can be seen under a microscope in a smear from the mucous membrane of the pharynx using certain techniques (staining, polarized light, dark field examination, etc.).
Why is it important to distinguish between a viral disease and a bacterial one?
The signs of bacterial and viral infections may be similar, but their treatment is completely different. Antibiotics are used for bacterial infections, and in some cases, symptomatic therapy (anti-inflammatory and painkillers). Antibiotics are ineffective for acute respiratory viral infections and flu. Antiviral and antipyretic drugs are prescribed, as well as plenty of fluids.
Using antibiotics for a viral infection without a reason is at best useless, at worst dangerous for the body. In addition, a person may develop resistance to the antibiotic, and in the future it will be ineffective.
How to distinguish infections by blood and urine tests
To establish an accurate diagnosis, the doctor prescribes blood and urine tests.
In case of a viral disease in the blood:
- increased lymphocytes (more than 39%) and monocytes (more than 11%);
- ESR increases (up to 20–25 mm/hour);
- Leukocytes are reduced.
In urine analysis, as a rule, there are no characteristic deviations indicating the viral nature of the infection. But with a high fever, accompanied by severe and prolonged intoxication, acetone may appear in the blood.
In case of a bacterial infection, a general blood test reveals:
- leukocyte growth over 9 g/l;
- an increase in neutrophils by more than 72% and band neutrophils by more than 6%;
- increase in ESR over 10–15 mm/hour.
In the general urine analysis, changes are possible with infection of the urinary system (cystitis, pyelonephritis, etc.). In this case, the number of leukocytes and erythrocytes increases, protein appears. Also, with a strong fever, acetone may appear in the urine.
Regardless of whether the patient has a viral or bacterial infection, it is important to evaluate not only the tests, but also the clinical picture of the disease.
Treatment of viral and bacterial infections
Treatment of viral and bacterial infections differs greatly. Viral diseases are treated only with antiviral drugs .
What medications are prescribed to treat viral infections:
- M2 channel blockers. They disrupt viral replication by damaging the viral protein in infected cells. However, most viruses are resistant to drugs in this group 14 .
- Neuraminidase inhibitors. They inhibit the production of the enzyme that helps the virus enter and exit the cell. They are effective against the flu virus.
- Hemagglutinin inhibitors. They change the conformation — the spatial configuration of the hemagglutinin protein, which allows the virus to penetrate the body’s cells. This makes infection impossible.
- Leukocyte interferons. These are ready-made proteins with antiviral action that work like natural human immune substances. They can cause side effects and lose their effectiveness with prolonged use.
- Interferon inducers. Stimulate the production of your own interferons, strengthening your immunity.
Bacterial infections are treated with antibiotics and, when applied locally, antiseptic drugs.
If there is a reason and the doctor prescribes such treatment, you can use local antimicrobial agents recommended by a specialist: nasal drops, throat sprays, lozenges, inhalations. 15 However, in the instructions for use of each local remedy, you can find an indication of the need to consult a doctor again if the patient does not feel better within a certain period of time. In any case, whether the doctor prescribes systemic antibiotics (oral drugs) from the very beginning, or starts with local forms – the decision on such a prescription and its validity is on the doctor’s side, because he not only determines the presence or absence of a bacterial infection, but also recommends the necessary drug in this case, affecting a certain type of pathogen. If the disease caused by bacterial pathogens has dragged on and correctly prescribed antibacterial drugs do not help, it is necessary to conduct an in-depth examination, in which the doctor can include a test for sensitivity to antibiotics and thus determine a group of drugs suitable for the destruction of a specific pathogen.
Antibiotics can be used in mixed infections, when bacterial flora joins in as a complication against the background of ARVI. 16 Such cases are approximately 0.4 to 19% of all episodes of viral respiratory infection. 17
How to Reduce the Risk of Infections 18
Prevention is based on following simple recommendations:
- Wash your hands with soap often. If you don’t have access to water, use antiseptics or wet wipes.
- Try to keep as much distance as possible when talking to reduce the risk of infection if your interlocutor is sick.
- Avoid touching your eyes, nose or mouth unless absolutely necessary.
- Wear a protective mask during outbreaks. Change your mask every four hours.
- Lead a healthy lifestyle: get enough sleep, exercise, eat more protein, fruits and vegetables.
- Do not self-medicate. If you have signs of a viral infection, start treatment as soon as possible. This will help you recover faster and avoid the risk of developing a bacterial infection.
- Keep your home clean. Wash and disinfect all surfaces more often, ventilate the rooms.
Maintaining a healthy lifestyle will help minimize the risk of contracting viral and bacterial infections.
Briefly about the main thing
- Bacteria and viruses are very different. A virus is a simple form of life that cannot reproduce outside a living organism, while a bacterium is a full-fledged living organism.
- The type of pathogen can be determined with some degree of probability by the symptoms. A viral infection such as influenza or acute respiratory viral infection is characterized by clear liquid mucus from the nose, a dry cough, a sharp rise in temperature to 38.5°C and above, headache and loss of smell.
- Signs of a bacterial infection: thick yellow-green mucus from the nose and throat, wet cough, fever up to 38°C, damage to the ENT organs and paranasal sinuses. With a viral infection, the temperature can last up to five days, with a bacterial infection – usually longer.
- In some cases, the pathogen can be identified based on the results of blood tests and laboratory tests.
- Treatment for different types of infection also varies. Antiviral drugs are indicated to treat viral infections. Bacterial infections are treated with antibiotics and local antiseptics.