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Nasal discharge

A nasal swab is a microbiological test used to identify bacteria or fungi that can cause infections in the nose and sinuses. It is a test frequently recommended when bacterial rhinitis, sinusitis, or persistent upper respiratory tract infections are suspected, or when symptoms do not improve with standard treatment.

By collecting a sample directly from the nasal mucosa, the exudate allows for an accurate diagnosis of the pathogen involved and testing of its sensitivity to antibiotics, enabling the doctor to prescribe targeted and effective treatment.

A nasal swab is a quick, noninvasive procedure that is well tolerated by both adults and children, and it is an essential tool for the proper management of respiratory infections.

What is nasal discharge?

A nasal swab is a microbiological test in which a sample of secretions is collected from inside the nasal passages to identify the microorganisms responsible for upper respiratory tract infections. The test detects pathogenic bacteria, such as Staphylococcus aureus, Streptococcus pneumoniae, and Haemophilus influenzae, as well as certain fungi and opportunistic pathogens.

By culturing the sample in the laboratory and performing an antibiotic susceptibility test, the doctor can determine exactly which bacteria are present and which antibiotics are effective against them. In this way, the nasal swab helps in selecting the most appropriate treatment, preventing the unnecessary use of antibiotics and reducing the risk of bacterial resistance.

This test is recommended for both acute infections and chronic or recurrent cases, and is also useful for screening healthy carriers of pathogens with a high potential for transmission.

When is a nasal swab recommended?

A nasal swab is recommended when a bacterial infection of the nose or sinuses is suspected, as well as in various clinical situations where identifying the pathogen is essential for determining the appropriate treatment.

Clinical signs (symptoms that may suggest a bacterial infection)

A doctor may recommend a nasal swab if the following symptoms are present:

  • severe or persistent nasal congestion;
  • purulent nasal discharge (yellow, green, foul-smelling);
  • facial pain or pressure in the sinus area;
  • fever or altered general condition;
  • headache associated with nasal congestion;
  • difficulty breathing through the nose or a nasal voice;
  • symptoms that last longer than 7–10 days or worsen over time;
  • recurrent episodes of sinusitis.

Epidemiological Indications and Special Situations

Nasal secretions are useful in:

  • screening for Staphylococcus aureus carriers (including MRSA), especially in hospitals or group settings;
  • screening of individuals exposed to outbreaks of respiratory infections;
  • medical examinations for healthcare personnel, the food industry, or institutions (schools, daycare centers), at the doctor’s request;
  • suspected fungal infection of the nose.

Monitoring and Recurring Cases

Nasal secretions may also be recommended for:

  • monitoring the effectiveness of antibiotic treatment in persistent infections;
  • re-evaluation of patients with chronic or recurrent sinusitis;
  • confirmation of the eradication of a pathogen with high epidemiological potential, such as MRSA (Methicillin-resistant Staphylococcus aureus).

How is a nasal swab performed?

A nasal swab is a simple, quick, and noninvasive procedure that can be performed on both adults and children. Here's how it's done:

Patient Preparation

Before the sample is collected, the patient should gently blow their nose to remove any excess secretions. It is recommended that they avoid using nasal drops or topical medications 1–2 hours before the test, so as not to affect the results. 

Samples can be collected at any time of day, but for accuracy, it is recommended to avoid collecting them immediately after meals or nasal rinses.

Sampling Method

The doctor or laboratory staff inserts a sterile cotton swab into the nasal passages, gently touching the mucous membrane. The swab is gently rotated to collect secretions and any pathogens. 

The procedure takes only a few seconds and does not cause significant pain, though it may cause mild discomfort or a sensation similar to sneezing.

Handling the Evidence

The collected sample is placed in a special transport medium to maintain the viability of the microorganisms until it reaches the laboratory. It is important that the sample be processed as soon as possible—ideally within a few hours—to ensure accurate results.

Laboratory Analysis

The laboratory performs microbiological cultures to identify any bacteria or fungi present. If necessary, an antibiotic susceptibility test (antibiogram) is performed to determine the optimal treatment.

The procedure is safe and does not require any rest or special restrictions after the procedure.

Reference Values for Nasal Secretions

A nasal swab test is a qualitative test, which means it does not have standard numerical values; instead, the results indicate the presence or absence of certain microorganisms. The results are interpreted as follows:

Normal result

  • The exudate does not contain pathogenic bacteria or fungi;
  • The nasal flora present consists of commensal microorganisms, that is, normal microorganisms that do not cause disease (Staphylococcus epidermidis, Corynebacterium spp., etc.);
  • There are no signs of active bacterial inflammation.

Positive result

  • Pathogenic bacteria are detected: for example, Staphylococcus aureus, Streptococcus pneumoniae, Haemophilus influenzae;
  • Possible presence of pathogenic fungi in rare cases or in immunocompromised patients;
  • A positive result may be associated with clinical signs of infection (purulent discharge, congestion, fever, etc.).

Partial/contaminated result

  • The normal bacterial flora is mixed with opportunistic bacteria, but without significant clinical manifestations;
  • The test may need to be repeated if contamination or incomplete collection is suspected.

The results must be accurately interpreted by a doctor, in conjunction with the patient's symptoms and medical history, to determine whether antibiotic treatment or another intervention is necessary.

Limitations and Factors That May Influence Nasal Secretion Results

The results of a nasal swab test can be influenced by several factors that must be taken into account for a correct interpretation.

Harvesting Factors

  • Incomplete or superficial collection may result in the absence of pathogenic bacteria in the sample;
  • Contamination with bacteria from the skin or the external environment can lead to false-positive results;
  • Sampling must be performed by trained personnel using sterile materials.

Therapeutic Factors

  • Recent use of antibiotics or antifungal medications may reduce the number of detectable microorganisms;
  • The use of antiseptic nasal drops may negatively affect the test's sensitivity;
  • Symptomatic treatment with decongestants or nasal corticosteroids may temporarily alter the nasal flora.

Biological and Clinical Factors

  • The presence of a concurrent viral infection can alter the bacterial flora;
  • Chronic inflammation of the nasal mucosa or allergies can lead to increased nasal discharge without a bacterial infection;
  • The patient's age and immune status affect the quantity and type of detectable microorganisms.

Technical Laboratory Factors

  • Improper transport of the sample or delays in processing can reduce bacterial viability;
  • The use of inappropriate culture media or ineffective diagnostic methods can lead to false-negative or inconclusive results.

The results of a nasal swab test should be interpreted in a clinical context, taking into account the patient's medical history, symptoms, and recent treatments, in order to avoid misdiagnosis or unnecessary treatments.

Nasal secretions in relation to other tests

Nasal secretions provide important information about the microorganisms present in the upper respiratory tract, but for a complete diagnosis, it is often necessary to combine them with other tests. Combining multiple tests makes it possible to distinguish between bacterial, viral, allergic, or inflammatory infections and helps the doctor determine the optimal treatment.

Correlation with pharyngeal exudate

A pharyngeal swab is often recommended in conjunction with a nasal swab because:

  • Many bacteria can colonize both the nose and the throat at the same time (e.g., Staphylococcus aureus, Streptococcus pyogenes);
  • An upper respiratory tract infection can originate either in the nasopharynx or in the oropharynx;
  • Comparing the results can confirm an active infection or asymptomatic carriage.

Correlation with the complete blood count (CBC)

A complete blood count helps determine the type of infection:

  • Leukocytosis with neutrophilia suggests a bacterial infection;
  • Lymphocytosis is more common in viral infections;
  • Eosinophilia may indicate respiratory allergies, not an infection.

Thus, the presence of nasal discharge helps confirm the nature of the infection.

The Correlation with Allergy Tests

In allergic rhinitis, the nasal exudate is often negative. In this case, further investigations may include:

  • Total and specific IgE (allergy panel);
  • Prick skin tests.

This correlation helps clearly distinguish between infections and allergies, thereby avoiding unnecessary antibiotic treatments.

Correlation with PCR for Respiratory Viruses

When viral infections are suspected (influenza, RSV, adenovirus, rhinovirus, etc.), the results of the nasal swab may be supplemented by:

  • PCR respiratory panel, which rapidly detects viruses;
  • especially useful for children, the elderly, and in crowded environments.

Nasal swab cultures do not identify viruses; therefore, PCR is essential when symptoms suggest a viral cause.

Correlation with chest X-ray or CT scan

If symptoms worsen or a lower respiratory tract infection is suspected:

  • An X-ray can confirm bronchitis or pneumonia; a CT scan can provide information about possible sinusitis, otitis, or mastoiditis;
  • The results of the exudate analysis indicate possible pathogens involved, guiding the choice of treatment.

The Correlation with Sinusitis Tests

For persistent sinusitis, the following may also be recommended:

  • CT scan of the sinuses;
  • ENT endoscopy.

Nasal discharge may indicate the type of pathogen involved in the sinus infection.

Frequently Asked Questions About Nasal Discharge

Does nasal discharge hurt?

The swab may feel slightly uncomfortable because it reaches the back of the nasal cavity, but it is not painful. The procedure takes a few seconds and does not cause any damage to the mucous membrane.

Can I eat or drink before my nasal swab?

Yes. Nasal discharge does not require fasting. However, it is recommended that you avoid nasal sprays or nasal rinses for at least 6–8 hours beforehand.

Can I have a runny nose if I have a cold or a stuffy nose?

Yes. In fact, this is the right time—the symptoms increase the likelihood of detecting infectious agents. If the nose is very stuffy, the nurse can gently clear the nasal passage to allow for proper specimen collection.

How long will it take to get the results?

Generally, the results are ready within 24–48 hours, depending on the type of cultures and any necessary antibiotic susceptibility testing.

What does it mean if the result shows “Staphylococcus aureus present”?

Staphylococcus aureus can be:

  • pathogen, if there are symptoms of infection;
  • asymptomatic carriage, especially in cases of chronic rhinitis or among people with weakened immune systems.

The doctor determines whether treatment is necessary based on the clinical context.

Can I take an antibiotic before the test?

Ideally, you should avoid antibiotics for 7–10 days beforehand; otherwise, the results may be false negatives. If you are already taking antibiotics, let the lab and your doctor know.

Is a nasal swab required for admission to a group setting?

Not always. In some institutions (daycare centers, preschools, community centers), it may be required depending on the local epidemiological situation or if symptoms reappear. The rule is not universal.

Can nasal secretions detect viruses?

Through bacterial culture—no. To detect viruses, a respiratory PCR panel is required; this is recommended especially for children or in cases of severe viral infections.

Is a nasal swab necessary if I suspect sinusitis?

In some cases, yes. The discharge can identify the bacteria involved and help the doctor decide whether an antibiotic is necessary. However, for chronic or complicated sinusitis, imaging tests (CT scan, ENT endoscopy) are also required.

Does a negative result completely rule out infection?

Not always. Some bacteria can be difficult to detect, and if the patient has used antibiotics or nasal antiseptics, the result may be a false negative. The doctor will consider the result in light of the patient’s symptoms.

The Benefits of Tests Performed at the Elytis Laboratory

Nasal swab testing at the Elytis laboratory ensures that patients receive a rapid, accurate diagnosis performed under the safest possible conditions. The laboratory uses modern technology, standardized procedures, and experienced staff, which ensures precise and clinically relevant results.

Specimen collection performed by specialized medical personnel

Collecting nasal secretions is essential for accurate results. At Elytis, nurses are trained to collect samples correctly, without causing significant discomfort. In addition, sterile swabs and techniques that comply with international guidelines are used.

Fast processing and prompt delivery of results

The laboratory is equipped with modern microbiological processing lines, which allow for rapid turnaround times for results (typically 24–48 hours), reduce the risk of sample degradation, and provide quick access to antibiotic susceptibility testing, if necessary.

Interpretation of the results by medical specialists

The results are analyzed and validated by physicians specializing in clinical laboratory medicine and microbiology, ensuring an accurate interpretation of the identified bacterial flora, providing guidance on the need for antibiotic treatment, and offering a comprehensive assessment in the context of the patient’s symptoms.

Advanced laboratory techniques and highly sensitive cultures

Elytis uses high-quality selective culture media, high-performance incubators, and rapid pathogen identification methods. These elements increase the chances of detecting pathogenic microorganisms even in small quantities.

Strict sterility and quality control requirements

Every step, from sample collection to printing the results, is rigorously monitored. The laboratory implements internal quality control procedures, protocols to prevent sample contamination, and periodic audits to ensure compliance with international standards.

Easy access, quick appointments, and results available online

Patients benefit from flexible scheduling and minimal wait times, testing in a comfortable setting, and secure online access to their results, without having to make an additional trip.

Counseling and Guidance After Receiving the Results

Elytis provides clarification on the identified flora, recommendations on next steps, and appropriate medical consultation (ENT, pediatrics, family medicine). 

A nasal swab is an essential test for diagnosing upper respiratory tract infections, providing accurate information about the bacteria that can cause symptoms such as a stuffy nose, nasal discharge, facial pain, or recurrent infections. When interpreted correctly, in the context of the clinical presentation and other complementary tests, this test allows for the establishment of an effective treatment plan and helps avoid the unnecessary use of antibiotics.

Choosing Elytis Laboratory for your nasal swab test means accuracy, speed, safety, and professional medical support. Whether the test is recommended by your doctor or you’re requesting it as a preventive measure, our team ensures optimal conditions for a reliable result. Schedule a quick and safe sample collection at Elytis Laboratory!

Last revised: November 21, 2025

References: 

  • Cuffari, Benedette. “What Is a Nasopharyngeal Swab?” News-Medical.net, June 12, 2020, www.news-medical.net/health/What-is-a-Nasopharyngeal-Swab.aspx;
  • Lee, Rose A., et al. “Performance of Saliva, Oropharyngeal Swabs, and Nasal Swabs for SARS-CoV-2 Molecular Detection: A Systematic Review and Meta-Analysis.” Journal of Clinical Microbiology, Jan. 27, 2021, https://doi.org/10.1128/jcm.02881-20;
  • “Nasal Swab: MedlinePlus Medical Test.” Medlineplus.gov, medlineplus.gov/lab-tests/nasal-swab/;
  • “What Is a Nasopharyngeal Swab?” Cleveland Clinic, my.clevelandclinic.org/health/diagnostics/22878-nasopharyngeal-swab.