Differences Between Viral Tonsillitis and Bacterial Tonsillitis

Viral tonsillitis and bacterial tonsillitis are conditions that are included within the pharyngitis-type pictures. In any case, they present with differential symptoms and their treatments vary.

Written and verified by el biólogo Samuel Antonio Sánchez Amador.

Last update: 13 July, 2023

The tonsils are lymphoid organs that face the aerodigestive tract. These structures play an essential role in individual immunity, as they safeguard one of the most common entry points for viruses and bacteria throughout the human body. When they become inflamed, it is necessary to know the differences between viral tonsillitis and bacterial tonsillitis.

This may seem like an anecdotal difference, but the causative pathogen of any disease influences the type of treatment to be followed and the prognosis. For example, the use of antibiotics in viral tonsillitis is completely useless and will only increase the chances of successive infections. If you want to know more about the subject, keep reading.

What are tonsils?

Before entering fully into pathological terrain, it is necessary to briefly describe what the tonsils are and how they work. According to the National Cancer Institute, each tonsil can be defined as ‘one of the two masses of lymphoid tissue that are located on either side of the throat’. In other words, they are reddish lymphatic organs located on both sides of the edge of the soft palate.

The tonsils as a concept don’t only represent two isolated masses. Actually, the lymphoid tissue aggregates into a pharyngeal structure known as Waldeyer’s Ring. This is divided, in turn, into several types of tonsils with certain peculiarities:

• Pharyngeal tonsil: This is a mass of lymphoid tissue located near the internal opening of the nostrils. Immunoglobulins (antibodies) are produced in this area.
• Two tubal tonsils: These masses (one on each side) can be located near the inner opening of the Eustachian tube, a structure that connects the middle ear with the pharynx.
• Two palatine tonsils: These are the “typical” tonsils and are located in the oropharynx. They can be seen with the naked eye when you open your mouth wide as two reddish, wet masses on each side of the throat. In them, the most evident picture of inflammation occurs when we talk about tonsillitis.
• Lingual tonsils: As the name suggests, these lymphoid tissues are found on the tongue, specifically at its base.

All these lymphoid tissues have certain features in common, since they have a clear immune function. When they perceive a threat, the B and T lymphocytes that are located in them recognize the pathogen that has come into contact with the surface of the amygdala and destroy it (either by producing antibodies or directly phagocyting it).

What are the differences between viral and bacterial tonsillitis?

Tonsillitis is an infectious condition by nature. Pharyngitis can occur from various causes, but for the lymphoid tissue to become inflamed, there must always be a triggering pathogen. Here are the differences between viral tonsillitis and bacterial tonsillitis.

1. Different causal agents

The Mayo Clinic defines the term “tonsillitis” as ‘inflammation of the palatine tonsils, two oval-shaped masses of tissue located on either side of the back of the throat.’ As we’ll see later on, most cases are caused by viral agents.

Viral tonsillitis

Viral tonsillitis is the most common of the variants. Several viruses can cause it, including the following:

• Adenoviruses: these are viral agents with a nucleocapsid that contains a double strand of DNA. There are more than 50 adenoviral serotypes that cause infections from asymptomatic to severe (depending on the variant).
• Rhinoviruses: Rhinoviruses are the most common infectious agents in humans and cause the well-known common cold. They have a single strand of RNA.
• Influenzavirus: Influenza virus A and influenza virus B are the cause of flu symptoms. Both are RNA viral agents and are established in the population with periods of seasonality.
• Other causative viruses: Epstein-Barr virus, parainfluenza virus, measles virus, cytomegalovirus, respiratory syncytial virus, and other agents within this group are also capable of causing tonsillitis.

Depending on the virus, the clinical picture may consist only of tonsillitis or may occur with many more symptoms. For example, measles always materializes with inflammation of the tonsils, but it also manifests with skin rashes, low-grade fever, headache, and body itching.

Bacterial tonsillitis

Bacterial tonsillitis is less common than viral tonsillitis, although it tends to present certain peaks in prevalence in some age groups. Some of the causative agents of this table are listed below:

• Infectious group A streptococci: Group A streptococci (GAS) are responsible for the vast majority of bacterial pharyngitis. Interestingly, in English this type of tonsillitis receives its own name and is separated from the rest of the pictures (strep throat).
• Streptococcus pneumoniae: This gram-positive, spherical bacterium is the cause of various infections. It isn’t as common as GAS, but it is usually the second suspect in cases of bacterial tonsillitis.
• Mycoplasma pneumoniae: This small bacteria causes a type of atypical pneumonia related to cold agglutinin disease (CAD).
• Bordetella pertussis: An aerobic Gram-negative bacterium that causes pertussis or whooping cough. In addition to tonsillitis, this bacteria causes a very serious cough that can be fatal. As indicated by professional sources, more than 30,000 people die in the world from this clinical picture.
• Corynebacterium diphtheriae: Diphtheria caused by this microorganism is accompanied by tonsillitis. Most of the conditions are asymptomatic or mild, but in certain epidemiological outbreaks, mortality rates of up to 10% of those affected have been detected.

Strep throat causes tonsillitis and typical symptoms of infection, but in other cases things can get complicated without proper treatment. Diphtheria and whooping cough cause inflammation of the tonsils, but also cause difficulty swallowing, aggressive coughs and even breathing problems in the most serious cases.

2. Symptomatic differences

Other differences between viral tonsillitis and bacterial tonsillitis lie in the symptoms of each of the conditions. Before dissecting the particularities of each one of them, we show you the common ones in the following list:

• Red and swollen tonsils – This is the most common symptom of both variants. It can be seen with the naked eye.
• Throat pain.
• Difficulty, discomfort, or pain when swallowing.
• Fever.
• Hoarse, raspy, or breathy voice.
• Bad breath.

Depending on the causative agent, other associated symptoms may appear. The severity of the symptoms will also depend on the potency of the infectious agent.

However, there are certain baseline symptomatic differences between viral tonsillitis and bacterial tonsillitis. We’ll look at them separately.

2.1 Fever

As indicated by the Healthline professional portal, tonsillitis caused by group A streptococci (strep throat) has a higher fever than the viral variant. In the viral picture, a low-grade fever (not higher than 38°C) or mild fever is usually present, while in the bacterial one it’s common to reach temperatures of 38.3°C or more.

2.2 Lesions in the oral cavity

In both clinical pictures, the tonsils become inflamed due to the presence of a pathogen. However, in bacterial tonsillitis, small red dots can be seen on the palate. These are clinically called petechiae and refer to minor bleeding in the superficial oral capillaries.

2.3 Appearance of the tonsils

In viral tonsillitis, the tonsils are discolored, which gives them a more yellowish or whitish color. On the other hand, in the bacterial variant this tissue is much more reddened and very white nuclei of pus appear. Therefore, this last picture is somewhat more obvious at first glance.

2.4 Scarlet fever

Scarlet fever is a bacterial disease that occurs in some patients with strep throat (never viral). It is characterized by a red rash that begins all over the body, red lines in the skin folds, a flushed face, and a “strawberry tongue” (red, raised, and covered in a white coating). It occurs much more often in children 2 to 10 years of age.

3. Duration of symptoms

As indicated by the Strepsils portal, viral tonsillitis appears with a symptomatic picture that lasts a few days and resolves on its own with the passage of time. The body fights off the causative virus and there are usually no major complications (unless the patient is already ill or immunosuppressed). In addition, the symptoms set in little by little with catarrhal symptoms.

On the other hand, bacterial tonsillitis occurs abruptly, is much more intense, and its symptoms last for an average of 7 to 10 days. This condition is usually ruled out when the patient also shows a mild cough or runny nose, as these are typical catarrhal clinical signs of the viral variant.

4. Differential diagnosis

The diagnosis of tonsillitis can take several routes, as indicated by the StatPearls portal. However, it should be noted that the bacterial variant (strep throat) requires somewhat more sophisticated detection methods. When the patient arrives at the clinic, the following standardized protocols are taken:

1. Use of a lighted instrument to view the pharyngeal cavity of the patient. As we have already said, the conformation of the tonsils says a lot about the type of condition. Furthermore, petechiae are unique to the bacterial variant.
2. Search for symptoms of scarlet fever by the body. If present, it’s related to streptococcal bacterial infection.
3. Palpation of the patient’s neck. In this way, the professional is able to notice the level of swelling of the lymph nodes.
4. Lung auscultation. If the infection has spread to the lung area, much more urgent care is required.

Although there are visible differences between viral tonsillitis and bacterial tonsillitis, one of the two conditions cannot be ruled out until laboratory tests are performed. For the medical professional to make a diagnosis, a sample of the patient’s oropharyngeal mucosa is taken and sent to the laboratory.

Strep antigen test

In recent years, a very rapid method of detecting bacterial tonsillitis has been developed. The rapid antigen testing streptococci (Rapid Strep Test in English, RST) allows a patient results in half an hour, but isn’t reliable in 100% of cases.

To perform this test, a swab is obtained from the patient’s oral mucosa and placed in a special device. By capillarity and other processes, the sample “moves” and comes into contact with specific antibodies for streptococci. If antigen-antibody binding occurs, a positive band is stained on the device, and infection is confirmed.

If the result is positive, the probability that the symptomatic patient will have bacterial tonsillitis is very high. In any case, it should be noted that up to 20% of the population has these microorganisms in their pharyngeal area without developing disease, so the presence of streptococcus doesn’t always have to be the cause of the infectious picture.

5. The treatments are different

The last of the differences between viral tonsillitis and bacterial tonsillitis lies in the treatment. In its viral variant, this condition has no pharmacological cure, since it is the patient’s own immune system that must be in charge of fighting the viral agent. However, medications such as Tylenol or ibuprofen can be helpful in reducing symptoms.

In addition to the aforementioned conditions, bacterial tonsillitis may require the administration of antibiotics.

Similar pictures, but with a different solution

The differences between viral tonsillitis and bacterial tonsillitis are multiple, but the most important of all lies in the treatment to be followed in each condition. Taking antibiotics for a viral infection isn’t only useless, but it can lead to the appearance of multi-resistant bacterial strains in the future due to overexposure.

For all these reasons, we recommend that you always go to the doctor in case of tonsillitis. If it’s viral you won’t have to worry (in most cases), but in its bacterial form you’ll have to follow a fairly strict antibiotic treatment. The last tip is self-explanatory: don’t self-medicate and you won’t have problems.